[Stress distribution in abutment teeth and related tissues under different design of connector: three-dimensional finite element analysis].

PubMed

Bai, Li-Ming; Li, Guo-Qiang; Zhang, Qiang; Dong, Xian

2016-08-01

To compare the stress distribution in abutment teeth and related tissues under the same material and different loading between improved major connector design and traditional major connector design. One 55-year-old male patient with unilateral maxillary first molar and second molar missing was chosen. The stress distribution in abutment teeth and related tissues were evaluated with spiral CT scanning, Mimics, Geomagic Studio software, a study model was built and finite element analysis was performed using ANSYS software. With the improved major connector design, the stress of abutment decreased significantly, the stress of periodontal decreased, the stress of edentulous mucosa increased significantly and became more balanced, the trend of stimulated absorption of alveolar bone decreased. For patients with distal free defect of dentition, the design of improved major connector has the effect of stress interruption, can protect the abutment better, detract the stress of the denture and has an good protective effect on the edentulous mucosa and alveolar bone.

Influence of the expansion screw height on the dental effects of the hyrax expander: a study with finite elements.

PubMed

Araugio, Rafael Marques de Sousa; Landre, Jánes; Silva, Diana de Lourdes Almeida; Pacheco, Wellington; Pithon, Matheus Melo; Oliveira, Dauro Douglas

2013-02-01

Our objective was to evaluate the influence of the expansion screw height of a hyrax expander on the degree of dental inclination during rapid maxillary expansion by using the finite element method. The hyrax expander and the maxillary arch were modeled by using Solidworks software (Dassault Systèmes, Paris, France). Three distinct finite element method models were created by simulating different screw heights relative to the plane that intersected the center of resistance of the maxillary first molars. These 3 relative positions were 10 mm below the maxillary first molars' center of resistance, at the same level as the maxillary first molars' center of resistance, and 10 mm above the maxillary first molars' center of resistance. The initial activation of the expanders was simulated, and tooth displacements for each finite element method model were registered in the buccolingual, corono-apical, and mesiodistal directions. The simulations tested showed that the 3 hyrax screw heights had different dental tipping tendencies. When the screw was simulated below the maxillary first molars' center of resistance, buccal tipping of the crowns and lingual tipping of the roots were registered. This tendency decreased when the screw was simulated at the same level as the maxillary first molars' center of resistance. However, when the screw was simulated above the maxillary first molars' center of resistance, the tipping tendency was inverted, with the crowns displaying lingual tipping and the roots displaying buccal tipping. These findings might explain the importance of carefully planning the height of the hyrax expander screw, since, depending on this position, different tooth movements can be achieved. From an orthopedic perspective, the ideal screw position might be slightly above the maxillary first molars' center of resistance; this would generate less dental tipping. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Reconstruction of dietary habits on the basis of dental microwear and trace elements analysis of individuals from Gán cemetery (district Galanta, Slovakia).

PubMed

Tibenská, Kristína Domonkosová; Bodoriková, Silvia; Katina, Stanislav; Kovácsová, Veronika; Kubová, Jana; Takács, Michal

2010-01-01

The aim of the study was to determine the diet of a historical human population. Dental microwear and trace elements were analyzed. Although 38 individuals had been buried in the cemetery, only 13 of them were suitable for the analysis of trace elements and 17 skeletal remains for microwear analysis. Buccal microwear has been studied in a sample of 17 teeth from Gán cemetery. Teeth molds of the buccal surface were obtained and observed at 120x magnification with a scanning electron microscope (SEM). Length and orientation of each striation have been determined with a SigmaScan Pro 5.0 image analysis program. The results of the analysis from Gán were compared with the previous study in a sample of 153 molar teeth from different modern hunter-gatherer, pastorals, and agriculturalist groups, with different diets (Inuit, Fueguians, Bushmen, Australian aborigines, Andaman's, Indians from Vancouver, Veddahs, Tasmanians, Lapps, and Hindus), preserved at museum collections. Buccal dental microwear density and length by orientation showed almost an inclination to hunter-gatherers from tropic and arid climates. The sample for the trace elements analysis consisted of 10 permanent molars and 3 permanent premolars. All analyzed teeth were intact, with fully developed roots, without dental caries, calculus and abrasion. Samples were analyzed using the method of optical emission spectrometry with inductively coupled plasma. Three elements: Ca, Sr, and Zn were chosen as basic diet determinants. Concentrations of these elements and their ratios were used for description of a relative proportion of plant and animal protein in a diet. The values of the Sr and Zn concentrations indicate that a diet of investigated population was rich in plant food. Higher Sr values in women can indicate lower proportion of animal protein in a diet, but significant differences have not been found. Differences between non-adult and adult individuals and between individuals with and without grave furnishings have also not been significant.

Reconstructing temporal variation of fluoride uptake in eastern grey kangaroos (Macropus giganteus) from a high-fluoride area by analysis of fluoride distribution in dentine.

PubMed

Kierdorf, Horst; Rhede, Dieter; Death, Clare; Hufschmid, Jasmin; Kierdorf, Uwe

2016-04-01

Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of root canal treatment procedures with a novel rotary nickel titanium instrument (TRUShape) on stress in mandibular molars: a comparative finite element analysis.

PubMed

Bonessio, Noemi; Arias, Ana; Lomiento, Guiseppe; Peters, Ove A

2017-01-01

The aim of this study was to investigate and compare, via finite element analysis (FEA), the effects of endodontic access and canal preparation on stress distribution under functional loading of a mandibular molar treated with novel (TRUShape) and conventional (Vortex) rotary root canal preparation instruments. Identical plastic mandibular molars with natural anatomy had all 4 canals shaped with either TRUShape or a conventional rotary, Vortex (#20 and #30, both by Dentsply Tulsa Dental). Finite element analysis was used to evaluate stress distribution in untreated and treated models. Micro-computed tomography (MCT) of the extracted teeth shaped in vitro was used to inform the FEA model regarding the geometry of root canals and external surfaces. Modeling the intact periodontal support and cancellous/cortical bone was based on anatomical data. Profiles of average and maximum von Mises stresses in dentin of the four treated conditions under functional loading were compared to the untreated model. This comparison was performed for each tooth model with and without root canal obturation and composite restoration. On average, the dentin sections with the most changes after preparation were located in the access cavity, with average stress increase up to +5.7, +8.5, +8.9, and +10.2 % for the TRUShape #20, Vortex #20, TRUShape #30 and Vortex #30, respectively, relative to the untreated model. Within the root canal system, the average stress differences were smaller than <5 % with lower values for TRUShape preparation. A reduction of the average stress in the access cavity was observed as an effect of the composite restoration, while about the same von Mises stress' profiles were found into the root canal. In this finite element analysis, preparation of the access cavity resulted in increased von Mises stresses under functional occlusal load. The limited (up to 0.7 %) retained radicular dentin in the TRUShape versus the Vortex cavity proved effective in reducing masticatory stresses. The bonded restoration modeled in this study only partially counterbalance the combined effects of access cavity and root canal preparation.

In-situ growth of ZIF-8 on layered double hydroxide: Effect of Zn/Al molar ratios on their structural, morphological and adsorption properties.

PubMed

Yang, Yingli; Yan, Xinlong; Hu, Xiaoyan; Feng, Rui; Zhou, Min

2017-11-01

In-situ growth of Zeolite imidazolate frameworks (ZIFs) on layered double hydroxides (LDHs) to form porous composites is a promising and challenging strategy to develop materials for separation application. Herein, the Zn-Al LDH with different Zn/Al molar ratios was prepared and used as matrix for the growth of ZIF-8 on its surface. The resulting composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 physisorption, thermogravimetric (TG), scanning electron microscope (SEM) and elemental analysis followed by testing for As V removal from aqueous solution. Results showed that ZIF-8 could form on the surface of LDH with different Zn/Al molar ratios. At low Zn/Al molar ratios, the morphology and surface area of the ZIF/LDH composites and the content of ZIF-8 in the composites were little affected by the Zn/Al molar ratio. With increasing Zn/Al molar ratio, ZIF-8/LDH exhibited a lower surface area, which resulted from reduced content of ZIF-8 caused by impurities generated in the LDH matrix. All ZIF-8/LDH samples showed high As V adsorption capacity, which was significantly higher than that of pure LDH or ZIF-8. Copyright © 2017 Elsevier Inc. All rights reserved.

A Survey of Removable Partial Denture (RPD) Retentive Elements in Relation to the Type of Edentulism and Abutment Teeth Found in Commercial Laboratories, Athens, Greece

PubMed Central

Sotiriou, Michael; Zissis, Alcibiades

2014-01-01

Objective The aim of this survey was to record removable partial denture (RPD) retentive elements and abutment teeth in partially edentulous patients, identified in commercial laboratories in Athens, Greece. Material and Methods 628 master casts with the corresponding cast metal frameworks used in the construction of RPDs were evaluated. Casts were photographed to identify the number and position of existing teeth, the partial edentulism class and the retentive elements. Prevalence tables and the x2 test were used for the statistical analysis of the collected data (α=.05). Results There were 276 maxillary (43.9%) and 352 (56.1%) mandibular casts. Maxillary edentulism entailed almost a total absence of right third molars in 96.7% and left third molars 96.0% of casts, with lower rates for the first and second molars. Edentulism in the posterior mandible presented a similar pattern. The most profound findings concerning retentive elements were: 91.9% of the retainers used were clasps and the remaining 8.1% were attachments. Of the clasps used, 48.9% were of the Roach Τ type, a finding more common in Kennedy Class I as compared to other Kennedy Classes (p<0.01). The circumferential clasps accounted for 19.3% of the total clasps used, and it was less frequently presented (8.8%) in Kennedy I Classes (p<0.01). Conclusions Roach clasps were used in the majority of cases whereas RPI clasps and attachments were rarely used. PMID:27688367

Three-dimensional finite element analysis of the stress distribution pattern in a mandibular first molar tooth restored with five different restorative materials.

PubMed

D'souza, Kathleen Manuela; Aras, Meena Ajay

2017-01-01

Badly broken or structurally compromised posterior teeth are frequently associated with crown/root fracture. Numerous restorative materials have been used to fabricate indirect full-coverage restorations for such teeth. This study aims to evaluate and compare the effect of restorative materials on the stress distribution pattern in a mandibular first molar tooth, under varying loading conditions and to compare the stress distribution pattern in five commonly used indirect restorative materials. Five three-dimensional finite element models representing a mandibular first molar tooth restored with crowns of gold, porcelain fused to metal, composite (Artglass), alumina-based zirconia (In-Ceram Zirconia [ICZ]), and double-layered zirconia-based materials (zirconia core veneered with porcelain, Lava) were constructed, using a Finite Element Analysis Software (ANSYS version 10; ANSYS Inc., Canonsburg, PA, USA). Two loading conditions were applied, simulating maximum bite force of 600 N axially and normal masticatory bite force of 225 N axially and nonaxially. Both all-ceramic crowns allowed the least amount of stress distribution to the surrounding tooth structure. In maximum bite force-simulation test, alumina-based all-ceramic crown displayed the highest von Mises stresses (123.745 MPa). In the masticatory bite force-simulation test, both all-ceramic crowns (122.503-133.13 MPa) displayed the highest von Mises stresses. ICZ crown displayed the highest peak von Mises stress values under maximum and masticatory bite forces. ICZ and Lava crowns also allowed the least amount of stress distribution to the surrounding tooth structure, which is indicative of a favorable response of the underlying tooth structure to the overlying full-coverage indirect restorative material. These results suggest that ICZ and Lava crowns can be recommended for clinical use in cases of badly damaged teeth.

Stress and Reliability Analysis of a Metal-Ceramic Dental Crown

NASA Technical Reports Server (NTRS)

Anusavice, Kenneth J; Sokolowski, Todd M.; Hojjatie, Barry; Nemeth, Noel N.

1996-01-01

Interaction of mechanical and thermal stresses with the flaws and microcracks within the ceramic region of metal-ceramic dental crowns can result in catastrophic or delayed failure of these restorations. The objective of this study was to determine the combined influence of induced functional stresses and pre-existing flaws and microcracks on the time-dependent probability of failure of a metal-ceramic molar crown. A three-dimensional finite element model of a porcelain fused-to-metal (PFM) molar crown was developed using the ANSYS finite element program. The crown consisted of a body porcelain, opaque porcelain, and a metal substrate. The model had a 300 Newton load applied perpendicular to one cusp, a load of 30ON applied at 30 degrees from the perpendicular load case, directed toward the center, and a 600 Newton vertical load. Ceramic specimens were subjected to a biaxial flexure test and the load-to-failure of each specimen was measured. The results of the finite element stress analysis and the flexure tests were incorporated in the NASA developed CARES/LIFE program to determine the Weibull and fatigue parameters and time-dependent fracture reliability of the PFM crown. CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/Or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program.

Tooth Eruption Results from Bone Remodelling Driven by Bite Forces Sensed by Soft Tissue Dental Follicles: A Finite Element Analysis

PubMed Central

Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

2013-01-01

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true ‘eruptive force’ is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, ‘biological response units’ in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the surrounding bony crypt, with the effect of enabling tooth eruption into the mouth. PMID:23554928

Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis.

PubMed

Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

2013-01-01

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true 'eruptive force' is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, 'biological response units' in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the surrounding bony crypt, with the effect of enabling tooth eruption into the mouth.

Stress distribution of various designs of prostheses on short implants or standard implants in posterior maxilla: a three dimensional finite element analysis

PubMed Central

JOMJUNYONG, K.; RUNGSIYAKULL, P.; RUNGSIYAKULL, C.; AUNMEUNGTONG, W.; CHANTARAMUNGKORN, M.; KHONGKHUNTHIAN, P.

2017-01-01

SUMMARY Introduction. Although many previous studies have reported on the high success rate of short dental implants, prosthetic design still plays an important role in the long-term implant treatment results. This study aims to evaluate stress distribution characteristics involved with various prosthetic designs on standard implants or short implants in the posterior maxilla. Materials and methods. Six finite element models were simulated representing the missing first and second maxillary molars. A standard implant (PW+ implant: 5.0×10 mm) and a short implant (PW+ implant: 5.0×6.0 mm) were applied under the various prosthetic conditions. The peri-implant maximum bone stress (V on mises stress) was evaluated when 200 N 30° oblique load was applied. A type III bone was approximated and complete osseous integration was assumed. Results. Maximum Von mises stress was numerically located at the cortical bone around the implant neck in all models. In every standard implant model shows better stress distribution. Stress values and concentration area decreased in the cortical and cancellous bone when implants were splinted in both the standard and short implant models. With regard to the non-replacing second molar models found that the area of stress at the cortical bone around the first molar implant to be more intensive. Moreover, in the non-replacing second molar models, the stress also spread to the second pre-molar in both the standard and short implant models. Conclusions. The length of the implant and prosthetics designs both affect the stress value and distribution of stress to the cortical and cancellous bones around the implant. PMID:29682254

Construction of a three-dimensional finite element model of maxillary first molar and it's supporting structures

PubMed Central

Begum, M. Sameena; Dinesh, M. R.; Tan, Kenneth F. H.; Jairaj, Vani; Md Khalid, K.; Singh, Varun Pratap

2015-01-01

The finite element method (FEM) is a powerful computational tool for solving stress-strain problems; its ability to handle material inhomogeneity and complex shapes makes the FEM, the most suitable method for the analysis of internal stress levels in the tooth, periodontium, and alveolar bone. This article intends to explain the steps involved in the generation of a three-dimensional finite element model of tooth, periodontal ligament (PDL) and alveolar bone, as the procedure of modeling is most important because the result is based on the nature of the modeling systems. Finite element analysis offers a means of determining strain-stress levels in the tooth, ligament, and bone structures for a broad range of orthodontic loading scenarios without producing tissue damage. PMID:26538895

[Finite element analysis of the stress distribution of two-piece post crown with different adhesives ].

PubMed

He, Lihui; Liu, Lijie; Gao, Bei; Gao, Shang; Chen, Yifu; Zhihui, Liu

2013-08-01

To establish three-dimensional finite element model of two-piece post crown to the mandibular first molar residual roots, and analyze the stress distribution characteristic to the residual roots with different adhesives, so as to get the best combination under different conditions. The complete mandibular first molar in vitro was selected, the crown was removed along the cemento-enamel junction, then the residual roots were scanned by CT. CT images were imported into a reverse engineering software, and the three-dimensional finite element model of the mandibular first molar residual roots was reconstructed. Titanium two-piece post crown of the mandibular first molar residual roots was produced, then was scanned by CT. The model was reconstructed and assembled by MIMICS. The stress distribution of the root canal and root section under the vertical load and lateral load with different bonding systems were analyzed. Three-dimensional finite element model of two-piece post crown to the mandibular first molar residual roots was established. With the increasing of elastic modulus of the adhesives, the maximum stress within the root canal was also increasing. Elastic modulus of zinc phosphate was the biggest, so the stress within the root canal was the biggest; elastic modulus of Superbond C&B was the smallest, so the stress within the root canal was the smallest. Lateral loading stress was much larger than the vertical load. Under vertical load, the load on the root section was even with different bonding systems. Under lateral load, the maximum stress was much larger than the vertical load. The stress on the root section was minimum using zinc phosphate binder, and the stress on the root section was maximum using Superbond C&B. In two-piece post crown restorations, there is significant difference between different adhesives on tooth protection. When the tooth structure of the root canal orifices is weak, in order to avoid the occurrence of splitting, the larger elastic modulus bonding system is the first choice, such as zinc phosphate binder. When the resistance form of the root canal orifices is good enough but the root is too weak, it is suggested that the smaller elastic modulus bonding system is the first choice, such as Superbond C&B.

Repeatability and reproducibility of intracellular molar concentration assessed by synchrotron-based x-ray fluorescence microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merolle, L., E-mail: lucia.merolle@elettra.eu; Gianoncelli, A.; Malucelli, E., E-mail: emil.malucelli@unibo.it

2016-01-28

Elemental analysis of biological sample can give information about content and distribution of elements essential for human life or trace elements whose absence is the cause of abnormal biological function or development. However, biological systems contain an ensemble of cells with heterogeneous chemistry and elemental content; therefore, accurate characterization of samples with high cellular heterogeneity may only be achieved by analyzing single cells. Powerful methods in molecular biology are abundant, among them X-Ray microscopy based on synchrotron light source has gaining increasing attention thanks to its extremely sensitivity. However, reproducibility and repeatability of these measurements is one of the majormore » obstacles in achieving a statistical significance in single cells population analysis. In this study, we compared the elemental content of human colon adenocarcinoma cells obtained by three distinct accesses to synchrotron radiation light.« less

Finite element method (FEM) analysis of the force systems produced by asymmetric inner headgear bows.

PubMed

Geramy, Allahyar; Kizilova, Natalya; Terekhov, Leonid

2011-11-01

Extra-oral traction appliances were introduced more than a century ago and continue to be used to produce orthopaedic and/or dental changes in the maxilla. While force systems produced by asymmetric outer bows have been studied extensively, the force systems produced by asymmetric inner bows have been overlooked. To analyse the forces acting on the maxillary first molars: when the size of one bayonet bend is increased; when the point of application of the distalising force on the inner bow is moved to one side; when one molar is displaced palatally. Four FEM models of cervical headgear attached to maxillary first molars were designed in SolidWorks 2010 and transferred to an ANSYS Workbench Ver. 12.1. Model 1, each molar was 23 mm from the midpalatal line and the inner bow was symmetrical; Model 2, the left molar was displaced 4 mm towards the midpalatal line and the inner bow was symmetrical; Model 3, the molars were equidistant (23 mm) from the midpalatal line, but the left molar was engaged by a 2 mm larger bayonet bend; Model 4, the molars were equidistant (23 mm) from the midpalatal line but the join between the inner and outer bows was displaced 2 mm towards the left molar. In all FEM models, a 2N force was applied to the inner bow at the join between inner and outer bows and the energy transmitted to the teeth and the von Mises stresses on the molar PDLs were assessed. There were marked differences in the strain energy on the teeth and the von Mises stresses on their PDLs. A 14 to 20 per cent increase in energy and force was produced on the tooth closer to the symmetric plane of the headgear. In addition, the increase in energy produced a 30 to 62 per cent increase in the von Mises stresses within the PDLs. Small asymmetries in molar position, the size of a bayonet bend and the point of application of a force on an inner bow resulted in asymmetrical forces on the molars. These forces were higher on the molar closer to the symmetric plane of the headgear.

Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

NASA Astrophysics Data System (ADS)

Chandra, Sulekh; Kumar, Anil

2007-12-01

Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L 1) and semicarbazone (L 2) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L) 2(SO 4) and Cu(L) 2(SO 4) [where L = L 1 and L 2] which are of five coordinated square pyramidal geometry.

Elemental ratios for characterization of quantum-dots populations in complex mixtures by asymmetrical flow field-flow fractionation on-line coupled to fluorescence and inductively coupled plasma mass spectrometry.

PubMed

Menendez-Miranda, Mario; Fernandez-Arguelles, Maria T; Costa-Fernandez, Jose M; Encinar, Jorge Ruiz; Sanz-Medel, Alfredo

2014-08-11

Separation and identification of nanoparticles of different composition, with similar particle diameter, coexisting in heterogeneous suspensions of polymer-coated CdSe/ZnS quantum dots (QDs) have been thoroughly assessed by asymmetric flow field-flow fractionation (AF4) coupled on-line to fluorescence and inductively coupled plasma mass spectrometry (ICPMS) detectors. Chemical characterization of any previously on-line separated nanosized species was achieved by the measurement of the elemental molar ratios of every element involved in the synthesis of the QDs, using inorganic standards and external calibration by flow injection analysis (FIA). Such elemental molar ratios, strongly limited so far to pure single nanoparticles suspensions, have been achieved with adequate accuracy by coupling for the first time an ICP-QQQ instrument to an AF4 system. This hyphenation turned out to be instrumental to assess the chemical composition of the different populations of nanoparticles coexisting in the relatively complex mixtures, due to its capabilities to detect the hardly detectable elements involved in the synthesis. Interestingly such information, complementary to that obtained by fluorescence, was very valuable to detect and identify unexpected nanosized species, present at significant level, produced during QDs synthesis and hardly detectable by standard approaches. Copyright © 2014. Published by Elsevier B.V.

Realistic kinetic loading of the jaw system during single chewing cycles: a finite element study.

PubMed

Martinez Choy, S E; Lenz, J; Schweizerhof, K; Schmitter, M; Schindler, H J

2017-05-01

Although knowledge of short-range kinetic interactions between antagonistic teeth during mastication is of essential importance for ensuring interference-free fixed dental reconstructions, little information is available. In this study, the forces on and displacements of the teeth during kinetic molar biting simulating the power stroke of a chewing cycle were investigated by use of a finite-element model that included all the essential components of the human masticatory system, including an elastic food bolus. We hypothesised that the model can approximate the loading characteristics of the dentition found in previous experimental studies. The simulation was a transient analysis, that is, it considered the dynamic behaviour of the jaw. In particular, the reaction forces on the teeth and joints arose from contact, rather than nodal forces or constraints. To compute displacements of the teeth, the periodontal ligament (PDL) was modelled by use of an Ogden material model calibrated on the basis of results obtained in previous experiments. During the initial holding phase of the power stroke, bite forces were aligned with the roots of the molars until substantial deformation of the bolus occurred. The forces tilted the molars in the bucco-lingual and mesio-distal directions, but as the intrusive force increased the teeth returned to their initial configuration. The Ogden material model used for the PDL enabled accurate prediction of the displacements observed in experimental tests. In conclusion, the comprehensive kinetic finite element model reproduced the kinematic and loading characteristics of previous experimental investigations. © 2017 John Wiley & Sons Ltd.

REMOVAL OF CHLORIDE FROM AQUEOUS SOLUTIONS

DOEpatents

Hyman, M.L.; Savolainen, J.E.

1960-01-01

A method is given for dissolving reactor fuel elements in which the uranium is associated with a relatively inert chromium-containing alloy such as stainless steel. An aqueous mixture of acids comprising 2 to 2.5 molar hydrochloric acid and 4 to 8 molar nitric acid is employed in dissolving the fuel element. In order io reduce corrosion in subsequent processing of the resulting solution, chloride values are removed from the solution by contacting it with concentrated nitric acid at an elevated temperature.

Evaluation of Stress Distribution of Mini Dental Implant-Supported Overdentures in Complete Cleft Palate Models: A Three-Dimensional Finite Element Analysis Study.

PubMed

Soğancı, Gökçe; Yazıcıoğlu, Hüseyin

2016-01-01

Mini dental implants could be an alternative treatment method for prosthetic treatment of edentulous cleft palate. The aim of this study was to analyze stress distribution around the cortical bone and different plans using a varied number of mini dental implants in edentulous unilateral complete cleft palates. Three edentulous maxillary models were modified to create unilateral complete cleft palates. Mini dental implants (2.4 × 15 mm) were located as two mini implants at the premolar region, four mini implants at the premolar and molar region, and six mini implants at the first premolar, second premolar, and first molar regions in the models, respectively. Mucosa, o-ring/ball attachments, and overdentures were simulated. Vertical and horizontal loads of 100 N were applied on both the right and left molar teeth of the overdenture for each model. Maximum and minimum principal stress values and the distribution at cortical bone around the implants and cleft palates were evaluated by finite element analysis. Stress values under vertical loads were lower than values under horizontal loadings for all models. Stress values were found to be lower in the first model than in the second and third models. The highest stress values were found around implants in the second model. The unilateral feature of a complete cleft pattern affected the stress distribution. Stresses occured mostly around implants when the overdenture was supported by six implants; however, the stress distribution around implants was low with two implants because of tissue support.

MIH supplementation strategies: prospective clinical and laboratory trial.

PubMed

Baroni, C; Marchionni, S

2011-03-01

The use of calcium-phosphate casein on hypomineralized molars (molar incisor hypomineralization, MIH) has been proposed but not clinically investigated. Qualitative and quantitative effects of supplementation with a calcium-phosphate casein product on MIH molars were monitored over a period of three years. Molar replicas, minimally invasive biopsies and their SEM microphotographs, plus ESEM/EDX semi-quantitative peaks of elements present in affected enamel were evaluated. Mineralization, morphology, and porosity appeared markedly improved, with calcium and phosphate levels reaching almost normal levels at three years' follow-up. The hypothesis tested was rejected, since calcium-phosphate casein improved enamel morphology in vivo.

Heat Transfer and Thermal Stress Analysis of a Mandibular Molar Tooth Restored by Different Indirect Restorations Using a Three-Dimensional Finite Element Method.

PubMed

Çelik Köycü, Berrak; İmirzalıoğlu, Pervin

2017-07-01

Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA). A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period. The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4ºC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions. The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42ºC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations. © 2015 by the American College of Prosthodontists.

Syntheses and characterization of Ru(III) with chelating containing ONNO donor quadridentate Schiff bases.

PubMed

Refat, Moamen S; El-Korashy, Sabry A; Kumar, Deo Nandan; Ahmed, Ahmed S

2008-09-01

Complexes of ruthenium(III) with N,N'-disalicylidene-l,2-phenylenediamine (H2dsp), N,N'-disalicylidene-3,4-diaminotoluene (H2dst), 4-nitro-N,N'-disalicylidene-1,2-phenylenediamine (H2ndsp) and N,N'-disalicylidene ethylenediamine (H2salen) have been prepared and characterized by elemental analysis, molar conductivity, spectral methods (mid-infrared, 1H NMR and UV-vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that all these complexes are non-electrolytes. The electronic spectra measurements were used to infer the structures. The IR spectra of the ligands and their complexes are used to identify the type of bonding. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The four ligands and their complexes have been studied for their possible biological antifungal activity.

Investigation on phase transitions of 1-decylammonium hydrochloride as the potential thermal energy storage material

NASA Astrophysics Data System (ADS)

Dan, Wen-Yan; Di, You-Ying; He, Dong-Hua; Liu, Yu-Pu

2011-02-01

1-Decylammonium hydrochloride was synthesized by the method of liquid phase synthesis. Chemical analysis, elemental analysis, and X-ray single crystal diffraction techniques were applied to characterize its composition and structure. Low-temperature heat capacities of the compounds were measured with a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. Three solid-solid phase transitions have been observed at the peak temperatures of 307.52 ± 0.13, 325.02 ± 0.19, and 327.26 ± 0.07 K. The molar enthalpies and entropies of three phase transitions were determined based on the analysis of heat capacity curves. Experimental molar heat capacities were fitted to two polynomial equations of the heat capacities as a function of temperature by least square method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K based on the fitted polynomials.

Evaluation of dietary exposure to minerals, trace elements and heavy metals from the muscle tissue of the lionfish Pterois volitans (Linnaeus 1758).

PubMed

Hoo Fung, Leslie A; Antoine, Johann M R; Grant, Charles N; Buddo, Dayne St A

2013-10-01

Twenty-five samples of Pterois volitans caught in Jamaican waters were analyzed for 25 essential, non-essential and toxic elements using Graphite Furnace Atomic Absorption Spectrophotometry (GF-AAS), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Instrumental Neutron Activation Analysis (INAA). The mean values for calcium (355 mg/kg), copper (107 μg/kg), iron (0.81 mg/kg), potassium (3481 mg/kg), magnesium (322 mg/kg), manganese (0.04 mg/kg), selenium (0.47 mg/kg), sodium (700 mg/kg) and zinc (4.46 mg/kg) were used to estimate dietary intake. The percentage contribution to provisional tolerable weekly intake for a 70 kg male and a 65 kg female were also estimated for the toxic elements arsenic (1.28% M, 1.38% F), cadmium (0.26% M. 0.28% F), mercury (3.85% M, 4.15% F) and lead (0.17% M, 0.18% F). To further assess the risk of mercury toxicity and the role of mitigation provided by selenium, selenium-mercury molar ratios were calculated for all samples. All samples were shown to have a molar excess of selenium. In addition the suggested selenium health benefit value was calculated, and was positive for all samples. It was concluded that P. volitans appears to contribute modestly to mineral and trace element nutrition, while not being a significant contributor to dietary exposure of toxic elements. Copyright © 2013 Elsevier Ltd. All rights reserved.

[The design of removable appliances for tooth movement and tooth migration].

PubMed

Voss, H

1989-06-01

Removable/functional appliance therapy can still be further expanded and developed. Retentive elements in the anterior region increase anchorage. Thereby, active forces can be utilised without anchorage loss. Functional appliances are indicated following extraction, to maximise on tooth migration. In first molar extraction cases, treatment with activators is relatively straightforward. When considering premolar extraction cases with possible need for extraction later of the third molars as well, then one should consider extraction of the first permanent molars. With correct use of the appliance, it is possible to optimally align the second molar teeth as well as favourably influencing the soft tissue profile.

Biomechanical evaluation of different abutment-implant connections - A nonlinear finite element analysis

NASA Astrophysics Data System (ADS)

Ishak, Muhammad Ikman; Shafi, Aisyah Ahmad; Rosli, M. U.; Khor, C. Y.; Zakaria, M. S.; Rahim, Wan Mohd Faizal Wan Abd; Jamalludin, Mohd Riduan

2017-09-01

The success of dental implant surgery is majorly dependent on the stability of prosthesis to anchor to implant body as well as the integration of implant body to bone. The attachment between dental implant body and abutment plays a vital role in attributing to the stability of dental implant system. A good connection between implant body cavity to abutment may minimize the complications of abutment loosening and implant fractures as widely reported in clinical findings. The aim of this paper is to investigate the effect of different abutment-implant connections on stress dispersion within the abutment and implant bodies as well as displacement of implant body via three-dimensional (3-D) finite element analysis (FEA). A 3-D model of mandible was reconstructed from computed tomography (CT) image datasets using an image-processing software with the selected region of interest was the left side covering the second premolar, first molar and second molar regions. The bone was modelled as compact (cortical) and porous (cancellous) structures. Besides, three implant bodies and three generic models of abutment with different types of connections - tapered interference fit (TIF), tapered integrated screwed-in (TIS) and screw retention (SR) were created using computer-aided design (CAD) software and all models were then analysed via 3D FEA software. Occlusal forces of 114.6 N, 17.2 N and 23.4 N were applied in the axial, lingual and mesio-distal directions, respectively, on the top surface of first molar crown. All planes of the mandibular bone model were rigidly fixed. The result exhibited that abutment with TIS connection produced the most favourable stress and displacement outcomes as compared to other attachment types. This is due to the existence of integrated screw at the bottom portion of tapered abutment which increases the motion resistance.

Biomechanical Influence of Implant Neck Designs on Stress Distribution over Adjacent Bone: A Three-Dimensional Non-Linear Finite Element Analysis

NASA Astrophysics Data System (ADS)

Ikman Ishak, Muhammad; Shafi, Aisyah Ahmad; Mohamad, Su Natasha; Jizat, Noorlindawaty Md

2018-03-01

The design of dental implant body has a major influence on the stress dissipation over adjacent bone as numbers of implant failure cases reported in past clinical studies. Besides, the inappropriate implant features may cause excessive high or low stresses which could possibly contribute to pathologic bone resorption or atrophy. The aim of this study is to evaluate the effect of different configurations of implant neck on stress dispersion within the adjacent bone via three-dimensional (3-D) finite element analysis (FEA). A set of computed tomography (CT) images of craniofacial was used to reconstruct a 3-D model of mandible using an image-processing software. The selected region of interest was the left side covering the second premolar, first molar and second molar regions. The bone model consisted of both compact (cortical) and porous (cancellous) structures. Three dental implant sets (crown, implant body, and abutment) with different designs of implant neck – straight, tapered with 15°, and tapered with 30° were modelled using a computer-aided design (CAD) software and all models were then analysed via 3-D FEA software. Top surface of first molar crown was subjected to occlusal forces of 114.6 N, 17.2 N, and 23.4 N in the axial, lingual, and mesio-distal directions, respectively. All planes of the mandible model were rigidly constrained in all directions. The result has demonstrated that the straight implant body neck is superior in attributing to high stress generation over adjacent bone as compared to others. This may associate with lower frictional resistance produced than those of tapered designs to withstand the applied loads.

Lipase-catalyzed synthesis of fattythioic acids from palm oil.

PubMed

Al-Mulla, Emad A Jaffar

2011-01-01

The present work focuses on the synthesis of fattythioic acids (FTAs) by a one-step lipase catalyzed reaction of palm oil with carbonothioic S,S-acid using Lipozyme. The product was characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The effects of various reaction parameters such as reaction time, temperature, amount of enzyme, molar ratio of substrates, and various organic solvents of the reaction system were investigated. The optimum conditions to produce FTAs were respectively, incubation time, 20 h, temperature, 40°C, amount of enzyme, 0.05 g and molar ratio of carbonothioic S,S-acid to palm oil, 5.0:1.0. Hexane was the best solvent for this reaction. The conversion of the products at optimum conditions was around 91%.

Extruded upper first molar intrusion: Comparison between unilateral and bilateral miniscrew anchorage.

PubMed

Sugii, Mari Miura; Barreto, Bruno de Castro Ferreira; Francisco Vieira-Júnior, Waldemir; Simone, Katia Regina Izola; Bacchi, Ataís; Caldas, Ricardo Armini

2018-01-01

The aim of his study was to evaluate the stress on tooth and alveolar bone caused by orthodontic intrusion forces in a supraerupted upper molar, by using a three-dimensional Finite Element Method (FEM). A superior maxillary segment was modeled in the software SolidWorks 2010 (SolidWorks Corporation, Waltham, MA, USA) containing: cortical and cancellous bone, supraerupted first molar, periodontal tissue and orthodontic components. A finite element model has simulated intrusion forces of 4N onto a tooth, directed to different mini-screw locations. Three different intrusion mechanics vectors were simulated: anchoring on a buccal mini-implant; anchoring on a palatal mini-implant and the association of both anchorage systems. All analyses were performed considering the minimum principal stress and total deformation. Qualitative analyses exhibited stress distribution by color maps. Quantitative analysis was performed with a specific software for reading and solving numerical equations (ANSYS Workbench 14, Ansys, Canonsburg, Pennsylvania, USA). Intrusion forces applied from both sides (buccal and palatal) resulted in a more homogeneous stress distribution; no high peak of stress was detected and it has allowed a vertical resultant movement. Buccal or palatal single-sided forces resulted in concentrated stress zones with higher values and tooth tipping to respective force side. Unilateral forces promoted higher stress in root apex and higher dental tipping. The bilateral forces promoted better distribution without evidence of dental tipping. Bilateral intrusion technique suggested lower probability of root apex resorption.

How Heavy Are You? Find the Answer in the Periodic Table

ERIC Educational Resources Information Center

Woelk, Klaus

2015-01-01

In a classroom or take-home activity, students are challenged to write their name as a combination of chemical-element symbols and calculate "their" molar mass. Age-appropriate versions ranging from middle school to entry-level college classes are discussed. Acceptable molar-mass suggestions may be used in a competition for the heaviest…

Mercury species, selenium, metallothioneins and glutathione in two dolphins from the southeastern Brazilian coast: Mercury detoxification and physiological differences in diving capacity.

PubMed

Kehrig, Helena A; Hauser-Davis, Rachel A; Seixas, Tercia G; Pinheiro, Ana Beatriz; Di Beneditto, Ana Paula M

2016-06-01

In the present study, the concentration of trace elements, total mercury (Hg) and selenium (Se) and mercury forms (MeHg, Hginorg and HgSe) in the vulnerable coastal dolphins Pontoporia blainvillei and Sotalia guianensis were appraised and compared, using metallothioneins (MT) and glutathione (GSH) as biomarkers for trace element exposure. The trace element concentrations varied between muscle and liver tissues, with liver of all dolphin specimens showing higher Hg and Se concentrations than those found in muscle. Hg, MeHg and Hginorg molar concentrations showed a clear increase with Se molar concentrations in the liver of both dolphins, and Se concentrations were higher than those of Hg on a molar basis. Se plays a relevant role in the detoxification of MeHg in the hepatic tissue of both dolphins, forming Hg-Se amorphous crystals in liver. In contrast, MT were involved in the detoxification process of Hginorg in liver. GSH levels in P. blainvillei and S. guianensis muscle tissue suggest that these dolphins have different diving capacities. Muscle Hg concentrations were associated to this tripeptide, which protects dolphin cells against Hg stress. Copyright © 2016 Elsevier Ltd. All rights reserved.

MIH: epidemiologic clinic study in paediatric patient

PubMed Central

CONDÒ, R.; PERUGIA, C.; MATURO, P.; DOCIMO, R.

2012-01-01

SUMMARY The Molar Incisor Hypomineralization (MIH) is a qualitative and quantitative defect of the enamel structure of the first permanent molars, which may vary from 1 to 4 with involvement of maxillary and jaw permanent incisors. Aim. Aim of this study is that to evaluate, among 1500 paediatric patients chosen at random aged between 0 and 14 years, afferent by the Paediatric Dentistry of the Azienda Ospedialiera Policlinico Tor Vergata of Rome from 1996 to 2011, the incidents and the prevalence of the MIH distribution, and furthermore to ascertain the possible relationship with the data described in the literature. Results and discussion. From the sample of 1500 paediatric patients, the number of those affections from MIH has turned out to be pairs to 110 (7.3%) aged between 4 and 15 years, and an average age equal to 9.7. The incidence of the hypoplastic defects is greater in the elements of the permanents series in which the functional class mainly interested is that of the first molars, with a percentage of 39.8%. Regarding the elements of the deciduous series affections from hypoplasia, they turn out to be in all in number of 20 represented in 80% of the cases from the seconds molars while in the remaining 20% of the cases the items involved are the central incisors. About the percentage of elements involved in the MIH: the molars, involved with a frequency of 56%, turn out to be more hit regarding incisors (44%). As reported in the literature, it can be asserted that the MIH can hit in equal measure both the male sex that feminine one. Conclusions. MIH represents a condition quite frequent in the paediatric population. In managing this anomaly takes an essential role in the early diagnosis and in the differential one. The study done underlined the importance of a correct application of the therapeutic protocol which, starting from a careful diagnosis and articulating themselves in the execution of preventive treatments and in severe cases restorative and prosthetic, has the aim to certify the functionality and the aesthetic of the dental elements affected by MIH. PMID:23285408

MIH: epidemiologic clinic study in paediatric patient.

PubMed

Condò, R; Perugia, C; Maturo, P; Docimo, R

2012-04-01

The Molar Incisor Hypomineralization (MIH) is a qualitative and quantitative defect of the enamel structure of the first permanent molars, which may vary from 1 to 4 with involvement of maxillary and jaw permanent incisors. AIM.: Aim of this study is that to evaluate, among 1500 paediatric patients chosen at random aged between 0 and 14 years, afferent by the Paediatric Dentistry of the Azienda Ospedialiera Policlinico Tor Vergata of Rome from 1996 to 2011, the incidents and the prevalence of the MIH distribution, and furthermore to ascertain the possible relationship with the data described in the literature. RESULTS AND DISCUSSION.: From the sample of 1500 paediatric patients, the number of those affections from MIH has turned out to be pairs to 110 (7.3%) aged between 4 and 15 years, and an average age equal to 9.7. The incidence of the hypoplastic defects is greater in the elements of the permanents series in which the functional class mainly interested is that of the first molars, with a percentage of 39.8%. Regarding the elements of the deciduous series affections from hypoplasia, they turn out to be in all in number of 20 represented in 80% of the cases from the seconds molars while in the remaining 20% of the cases the items involved are the central incisors. About the percentage of elements involved in the MIH: the molars, involved with a frequency of 56%, turn out to be more hit regarding incisors (44%). As reported in the literature, it can be asserted that the MIH can hit in equal measure both the male sex that feminine one. CONCLUSIONS.: MIH represents a condition quite frequent in the paediatric population. In managing this anomaly takes an essential role in the early diagnosis and in the differential one. The study done underlined the importance of a correct application of the therapeutic protocol which, starting from a careful diagnosis and articulating themselves in the execution of preventive treatments and in severe cases restorative and prosthetic, has the aim to certify the functionality and the aesthetic of the dental elements affected by MIH.

Quercetin-Iron Complex: Synthesis, Characterization, Antioxidant, DNA Binding, DNA Cleavage, and Antibacterial Activity Studies.

PubMed

Raza, Aun; Xu, Xiuquan; Xia, Li; Xia, Changkun; Tang, Jian; Ouyang, Zhen

2016-11-01

Quercetin-iron (II) complex was synthesized and characterized by elemental analysis, ultraviolet-visible spectrophotometry, fourier transform infrared spectroscopy, mass spectrometry, proton nuclear magnetic resonance spectroscopy, thermogravimetry and differential scanning calorimetry, scanning electron micrography and molar conductivity. The low molar conductivity value investigates the non-electrolyte nature of the complex. The elemental analysis and other physical and spectroscopic methods reveal the 1:2 stoichiometric ratio (metal:ligand) of the complex. Antioxidant study of the quercetin and its metal complex against 2, 2-di-phenyl-1-picryl hydrazyl radical showed that the complex has much more radical scavenging activity than free quercetin. The interaction of quercetin-iron (II) complex with DNA was determined using ultraviolet visible spectra, fluorescence spectra and agarose gel electrophoresis. The results showed that quercetin-iron (II) complex can intercalate moderately with DNA, quench a strong intercalator ethidium bromide and compete for the intercalative binding sites. The complex showed significant cleavage of pBR 322 DNA from supercoiled form to nicked circular form and these cleavage effects were dose-dependent. Moreover, the mechanism of DNA cleavage indicated that it was an oxidative cleavage pathway. These results revealed the potential nuclease activity of complex to cleave DNA. In addition, antibacterial activity of complex on E.coli and S. aureus was also investigated. The results showed that complex has higher antibacterial activity than ligand.

Design and expected performance of a fast neutron attenuation probe for light element density measurements

DOE PAGES

Sweany, M.; Marleau, P.

2016-07-08

In this paper, we present the design and expected performance of a proof-of-concept 32 channel material identification system. Our system is based on the energy-dependent attenuation of fast neutrons for four elements: hydrogen, carbon, nitrogen and oxygen. We describe a new approach to obtaining a broad range of neutron energies to probe a sample, as well as our technique for reconstructing the molar densities within a sample. The system's performance as a function of time-of-flight energy resolution is explored using a Geant4-based Monte Carlo. Our results indicate that, with the expected detector response of our system, we will be ablemore » to determine the molar density of all four elements to within a 20–30% accuracy in a two hour scan time. In many cases this error is systematically low, thus the ratio between elements is more accurate. This degree of accuracy is enough to distinguish, for example, a sample of water from a sample of pure hydrogen peroxide: the ratio of oxygen to hydrogen is reconstructed to within 8±0.5% of the true value. Lastly, with future algorithm development that accounts for backgrounds caused by scattering within the sample itself, the accuracy of molar densities, not ratios, may improve to the 5–10% level for a two hour scan time.« less

Fibre Bragg grating sensing and finite element analysis of the biomechanics of the mandible

NASA Astrophysics Data System (ADS)

Silva, J. C. C.; Ramos, A.; Carvalho, L.; Nogueira, R. N.; Ballu, A.; Mesnard, M.; Pinto, J. L.; Kalinowski, Hypolito J.; Simoes, J. A.

2005-05-01

This paper describes the application of fibre Bragg grating (FBG) sensors to measure strains at the outer surface of a mandible. The strains were correlated to identical ones obtained with a numerical finite element model. For this purpose, a synthetic mandible was used and 4 Bragg sensors were glued to the mandible. Strain patterns were assessed for different load configurations which included the forces of the masseter and temporal muscles and occlusion loads on different tooth (incisor, canine and molar). Overall the strains obtained using different measuring methods were identical, namely for the case of symmetric loading. When loading was non-symmetric, strain differences were observed at one sensor.

μX-ray fluorescence analysis of traces and calcium phosphate phases on tooth tartar interfaces using synchrotron radiation

NASA Astrophysics Data System (ADS)

Abraham, J. A.; Grenón, M. S.; Sánchez, H. J.; Valentinuzzi, M. C.; Perez, C. A.

2007-07-01

Hard dental tissues like dentine and cementum with calcified deposits (dental calculi) were studied in several human dental pieces of adult individuals from the same geographic region. A couple of cross cuts were performed at dental root level resulting in a planar slice with calculus and dental tissue exposed for analysis. The elemental content along a linear path crossing the dentine-cementum-tartar interfaces and also all over a surface was measured by X-ray fluorescence microanalysis using synchrotron radiation (μSRXRF). The concentration of elemental traces like K, V, Cu, Zn, As, Br and Sr showed different features on the analyzed regions. The possible connections with the dynamic of mineralization and biological implications are discussed. The concentrations of major elements Ca and P were also determined and the measured Ca/P molar ratio was used to estimate the average composition of calcium phosphate phases in the measured points. A deeper knowledge of the variations of the elemental compositions and the changes of the different phases will help to a better understanding of the scarcely known mechanism of calculus growing.

Ab initio simulations of molten Ni alloys

NASA Astrophysics Data System (ADS)

Woodward, Christopher; Asta, Mark; Trinkle, Dallas R.; Lill, James; Angioletti-Uberti, Stefano

2010-06-01

Convective instabilities responsible for misoriented grains in directionally solidified turbine airfoils are produced by variations in liquid-metal density with composition and temperature across the solidification zone. Here, fundamental properties of molten Ni-based alloys, required for modeling these instabilities, are calculated using ab initio molecular dynamics simulations. Equations of state are derived from constant number-volume-temperature ensembles at 1830 and 1750 K for elemental, binary (Ni-X, X=Al, W, Re, and Ta) and ternary (Ni-Al-X, X=W, Re, and Ta) Ni alloys. Calculated molar volumes agree to within 0.6%-1.8% of available measurements. Predictions are used to investigate the range of accuracy of a parameterization of molar volumes with composition and temperature based on measurements of binary alloys. Structural analysis reveals a pronounced tendency for icosahedral short-range order for Ni-W and Ni-Re alloys and the calculations provide estimates of diffusion rates and their dependence on compositions and temperature.

Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids.

PubMed

Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A

2013-01-01

The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1 : 1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR ((1)H, (13)C, and (29)Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands.

The Mt. Gilead Cemetery Study: An Example of Biocultural Analysis from Western Georgia.

DTIC Science & Technology

1986-02-01

recognize against the lighter matrix at about 1.0 - 1.2 m below the original ground surface. At this point, the pans were dis- missed and the field crew...general soil matrix outside the grave fill. Detailed photographs of certain skeletal elements which exhibited pathologies were taken (color slides...and sharp. Of the molars, the roots of #3, #19, and #32 remained; #14 was in place but was 39 -.. hollowed halfway down the buccal roots by gingival

Angulated Dental Implants in Posterior Maxilla FEA and Experimental Verification.

PubMed

Hamed, Hamed A; Marzook, Hamdy A; Ghoneem, Nahed E; El-Anwar, Mohamed I

2018-02-15

This study aimed to evaluate the effect of different implant angulations in posterior maxilla on stress distribution by finite element analysis and verify its results experimentally. Two simplified models were prepared for an implant placed vertically and tilted 25° piercing the maxillary sinus. Geometric models' components were prepared by Autodesk Inventor then assembled in ANSYS for finite element analysis. The results of finite element analysis were verified against experimental trials results which were statistically analysed using student t-test (level of significance p < 0.05). Implant - abutment complex absorbed the load energy in case of vertical implant better than the case of angulated one. That was reflected on cortical bone stress, while both cases showed stress levels within the physiological limits. Comparing results between FEA and experiment trials showed full agreement. It was found that the tilted implant by 25° can be utilised in the posterior region maxilla for replacing maxillary first molar avoiding sinus penetration. The implant-bone interface and peri-implant bones received the highest Von Mises stress. Implant - bone interface with angulated implant received about 66% more stresses than the straight one.

Assessment of exposures and potential risks to the US adult population from the leaching of elements from gold and ceramic dental restorations.

PubMed

Richardson, G Mark; James, Kyle Jordan; Peters, Rachel Elizabeth; Clemow, Scott Richard; Siciliano, Steven Douglas

2016-01-01

Using data from the 2001 to 2004 US National Health and Nutrition Examination Survey (NHANES) on the number and placement of tooth restorations in adults, we quantified daily doses due to leaching of elements from gold (Au) alloy and ceramic restorative materials. The elements with the greatest leaching rates from these materials are often the elements of lowest proportional composition. As a result, exposure due to wear will predominate for those elements of relatively high proportional composition, while exposure due leaching may predominate for elements of relatively low proportional composition. The exposure due to leaching of silver (Ag) and palladium (Pd) from Au alloys exceeded published reference exposure levels (RELs) for these elements when multiple full surface crowns were present. Six or more molar crowns would result in exceeding the REL for Ag, whereas three or more crowns would be necessary to exceed the REL for Pd. For platinum (Pt), the majority of tooth surfaces, beyond just molar crowns, would be necessary to exceed the REL for Pd. Exposures due to leaching of elements from ceramic dental materials were less than published RELs for all components examined here, including having all restorations composed of ceramic.

Structures and standard molar enthalpies of formation of a series of Ln(III)–Cu(II) heteronuclear compounds with pyrazine-2,3-dicarboxylic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qi; Xie, Gang; Wei, Qing

2014-07-01

Fifteen lanthanide–copper heteronuclear compounds, formulated as [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 6}]·xH{sub 2}O (1–6(x=2), 8(x=3), 9–10(x=4)); [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 4}]·xH{sub 2}O (7, 12–13, 15(x=4), 14(x=5), 11(x=8)) (Ln(III)=La(1); Ce(2); Pr(3); Nd(4); Sm(5); Eu(6); Gd(7); Tb(8); Dy(9); Ho(10); Er(11); Tm(12); Yb(13); Lu(14); Y(15); H{sub 2}pzdc (C{sub 6}H{sub 4}N{sub 2}O{sub 4})=pyrazine-2,3-dicarboxylic acid) have been hydrothermally synthesized. All compounds were characterized by element analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analyses confirm that all compounds are isostructural and feature a 3D brick-like framework structure with (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 2}.8{sup 2})(6{sup 3}){sup 2}(6{sup 5}.8){sub 2} topology. Using 1 mol cm{supmore » −3} HCl(aq) as calorimetric solvent, with an isoperibol solution–reaction calorimeter, the standard molar enthalpies of formation of all compounds were determined by a designed thermochemical cycle. In addition, solid state luminescence properties of compounds 5, 6, 8 and 9 were studied in the solid state. - Graphical abstract: According to Hess' rule, the standard molar enthalpies of formation of Ln–Cu heterometallic coordination compounds were determined by a designed thermochemical cycle. - Highlights: • Fifteen lanthanide–copper heteronuclear isostructural compounds. • Structurally characterization by IR, X-ray diffraction and thermal analysis. • The standard molar enthalpy of formation. • Isoperibol solution–reaction calorimetry.« less

Method of making compound semiconductor films and making related electronic devices

DOEpatents

Basol, Bulent M.; Kapur, Vijay K.; Halani, Arvind T.; Leidholm, Craig R.; Roe, Robert A.

1999-01-01

A method of forming a compound film includes the steps of preparing a source material, depositing the source material on a base to form a precursor film, and heating the precursor film in a suitable atmosphere to form a film. The source material includes Group IB-IIIA alloy-containing particles having at least one Group IB-IIIA alloy phase, with Group IB-IIIA alloys constituting greater than about 50 molar percent of the Group IB elements and greater than about 50 molar percent of the Group IIIA elements in the source material. The film, then, includes a Group IB-IIIA-VIA compound. The molar ratio of Group IB to Group IIIA elements in the source material may be greater than about 0.80 and less than about 1.0, or substantially greater than 1.0, in which case this ratio in the compound film may be reduced to greater than about 0.80 and less than about 1.0. The source material may be prepared as an ink from particles in powder form. The alloy phase may include a dopant. Compound films including a Group IIB-IVA-VA compound or a Group IB-VA-VIA compound may be substituted using appropriate substitutions in the method. The method, also, is applicable to fabrication of solar cells and other electronic devices.

Indirect miniscrew anchorage: biomechanical loading of the dental anchorage during mandibular molar protraction-an FEM analysis.

PubMed

Holberg, Christof; Winterhalder, Philipp; Holberg, Nikola; Wichelhaus, Andrea; Rudzki-Janson, Ingrid

2014-01-01

While there are many studies in the literature addressing direct miniscrew anchorage, the biomechanical effects of indirect miniscrew anchorage remain unknown. The aim of the present study was to biomechanically analyze the load on the anchor teeth during mandibular molar protraction using different types of anchorage. Four finite element method (FEM) models of the right mandible were created using the morphological CT data of a 21-year-old male. All models were morphologically identical, but they differed in anchorage type (dental anchorage, direct miniscrew anchorage, indirect miniscrew anchorage with one anchor tooth, indirect miniscrew anchorage with two anchor teeth). To analyze the load on the dental anchorage during mandibular molar protraction, we measured the induced effective strain (µstrain) at specific control points on the alveolar bone. With indirect miniscrew anchorage, we observed that the effective strain at an average of 7.21 μstrain (one anchor tooth) or 6.57 μstrain (two anchor teeth) was almost as high as in pure dental anchorage where no miniscrew was used (mean 8.38 µstrain). In contrast, we noted significantly lower strain values in conjunction with direct miniscrew anchorage. We observed highly significant differences between direct and indirect simulated miniscrew anchorage (p=0.008). Our FEM results reveal relatively high loads on the dental anchorage when using indirect miniscrew anchorage. This may carry an increased risk of anchorage loss during mandibular molar protraction; however, further studies are necessary to confirm this.

Molarity (Aromic Density) of the Elements as Pure Crystals.

ERIC Educational Resources Information Center

Pauling, Linus; Herman, Zelek S.

1985-01-01

Provides background information for teachers on the atomic density of the elements as pure crystals. Atomic density is defined as the reciprocal of the atomic volume. Includes atomic-density diagrams which were prepared using the atomic-volume values given by Singman, supplemented by additional values for some allotropes. (JN)

Biology of biomechanics: Finite element analysis of a statically determinate system to rotate the occlusal plane for correction of a skeletal Class III open-bite malocclusion.

PubMed

Roberts, W Eugene; Viecilli, Rodrigo F; Chang, Chris; Katona, Thomas R; Paydar, Nasser H

2015-12-01

In the absence of adequate animal or in-vitro models, the biomechanics of human malocclusion must be studied indirectly. Finite element analysis (FEA) is emerging as a clinical technology to assist in diagnosis, treatment planning, and retrospective analysis. The hypothesis tested is that instantaneous FEA can retrospectively simulate long-term mandibular arch retraction and occlusal plane rotation for the correction of a skeletal Class III malocclusion. Seventeen published case reports were selected of patients treated with statically determinate mechanics using posterior mandible or infrazygomatic crest bone screw anchorage to retract the mandibular arch. Two-dimensional measurements were made for incisor and molar movements, mandibular arch rotation, and retraction relative to the maxillary arch. A patient with cone-beam computed tomography imaging was selected for a retrospective FEA. The mean age for the sample was 23.3 ± 3.3 years; there were 7 men and 10 women. Mean incisor movements were 3.35 ± 1.55 mm of retraction and 2.18 ± 2.51 mm of extrusion. Corresponding molar movements were retractions of 4.85 ± 1.78 mm and intrusions of 0.85 ± 2.22 mm. Retraction of the mandibular arch relative to the maxillary arch was 4.88 ± 1.41 mm. Mean posterior rotation of the mandibular arch was -5.76° ± 4.77° (counterclockwise). The mean treatment time (n = 16) was 36.2 ± 15.3 months. Bone screws in the posterior mandibular region were more efficient for intruding molars and decreasing the vertical dimension of the occlusion to close an open bite. The full-cusp, skeletal Class III patient selected for FEA was treated to an American Board of Orthodontics Cast-Radiograph Evaluation score of 24 points in about 36 months by en-masse retraction and posterior rotation of the mandibular arch: the bilateral load on the mandibular segment was about 200 cN. The mandibular arch was retracted by about 5 mm, posterior rotation was about 16.5°, and molar intrusion was about 3 mm. There was a 4° decrease in the mandibular plane angle to close the skeletal open bite. Retrospective sequential iterations (FEA animation) simulated the clinical response, as documented with longitudinal cephalometrics. The level of periodontal ligament stress was relatively uniform (<5 kPa) for all teeth in the mandibular arch segment. En-masse retraction of the mandibular arch is efficient for conservatively treating a skeletal Class III malocclusion. Posterior mandibular anchorage causes intrusion of the molars to close the vertical dimension of the occlusion and the mandibular plane angle. Instantaneous FEA as modeled here could be used to reasonably predict the clinical results of an applied load. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Impact of the lower third molar presence and position on the fragility of mandibular angle and condyle: A Three-dimensional finite element study.

PubMed

Antic, Svetlana; Vukicevic, Arso M; Milasinovic, Marko; Saveljic, Igor; Jovicic, Gordana; Filipovic, Nenad; Rakocevic, Zoran; Djuric, Marija

2015-07-01

The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3. In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Synthesis and in vitro microbial evaluation of La(III), Ce(III), Sm(III) and Y(III) metal complexes of vitamin B6 drug

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Al-Azab, Fathi M.; Al-Maydama, Hussein M. A.; Amin, Ragab R.; Jamil, Yasmin M. S.

2014-06-01

Metal complexes of pyridoxine mono hydrochloride (vitamin B6) are prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes are investigated. Some physical properties, conductivity, analytical data and the composition of the four pyridoxine complexes are discussed. The elemental analysis shows that the formed complexes of La(III), Ce(III), Sm(III) and Y(III) with pyridoxine are of 1:2 (metal:PN) molar ratio. All the synthesized complexes are brown in color and possess high melting points. These complexes are partially soluble in hot methanol, dimethylsulfoxide and dimethylformamide and insoluble in water and some other organic solvents. Elemental analysis data, spectroscopic (IR, UV-vis. and florescence), effective magnetic moment in Bohr magnetons and the proton NMR suggest the structures. However, definite particle size is determined by invoking the X-ray powder diffraction and scanning electron microscopy data. The results obtained suggested that pyridoxine reacted with metal ions as a bidentate ligand through its phenolate oxygen and the oxygen of the adjacent group at the 4‧-position. The molar conductance measurements proved that the pyridoxine complexes are electrolytic in nature. The kinetic and thermodynamic parameters such as: Ea, ΔH*, ΔS* and ΔG* were estimated from the DTG curves. The antibacterial evaluation of the pyridoxine and their complexes were also performed against some gram positive, negative bacteria as well as fungi.

[Finite element analysis of different load mode on tooth movement for space closure in patient with bimaxillary protrusion].

PubMed

Zhang, X B; Yin, Y F; Yao, H M; Han, Y H; Wang, N; Ge, Z L

2016-07-01

To investigate the stress distribution on the maxillary anterior teeth retracted with sliding mechanics and micro-implant anchorage using different retraction hook heights and positions. DICOM image data including maxilla and upper teeth were obtained with cone-beam CT. The three-dimensional finite element model was constructed using Mimics software. Brackets and archwire model were constructed using Creo software. The models were instantiated using Pro/Engineer software. Abaqus software was used to simulate the sliding mechanics by loading 2 N force on 0, 2, 4, 6, 8, 10 mm retraction hooks and three different positions, repectively. Rotation of the occlusal plane, the initial displacement and stress distribution of teeth were analyzed. Lingual rotation of maxillary central incisor(0.021°), gingival movement of the maxillary first molar(0.005 mm), and clockwise rotation of the maxillary occlusal plane(0.012°) were observed when the force application point located at the archwire level (0 mm). In contrast, 0.235° labial rotation of the maxillary central incisor, 0.015 mm occlusal movement of the maxillary first molar, and 0.075° anti-clockwise rotation of the maxillary occlusal plane were observed when the force application point located at the higher level(10 mm retraction hook). The more the force application point was located posteriorly at the archwire level, the less lingual rotation of the maxillary central incisor and the more buccal displacement of maxillary first molar was observed. Maxillary anterior tooth rotation and retraction, vertical displacement of posterior segment, and rotation of the occlusal plane could be controlled by adjusting the height and position of the retraction hook in space closure using miniscrew and sliding mechanics.

Trace elements records from vermetids aragonite as millennial paleo-oceanographic archives in the South-East Mediterranean

NASA Astrophysics Data System (ADS)

Jacobson, Yitzhak; Yam, Ruth; Shemesh, Aldo

2017-04-01

The Mediterranean Sea is a region under high anthropogenic stress, thus a hotspot for climate change studies. Natural conditions, such as SST, productivity, precipitation and dust fluxes along with human induced activity affect seawater chemistry. We study millennial variability of trace elements in East Mediterranean Sea high-resolution records, in attempt to connect them to environmental factors. The Mediterranean reef builder Vermetid, D. petraeum is a sessile gastropod, secreting its aragonite shells in tidal zones. Cores of Vermetid reefs from the South Eastern Mediterranean (Israel) were previously analyzed by Sisma?Ventura et al. (2014) to reconstruct seawater surface temperature (SST) and δ13C of dissolved inorganic carbon (DIC). In this study we analyzed trace elements of these vermetid cores, and reconstructed millennial records of elements to calcium (el/Ca) molar ratios. Vermetid trace element contents from recent decades are mostly in agreement with known values for marine biogenic aragonites from corals and mollusk. We divide vermetid trace element records into three element groups: 1) Sr and U are related to SST and DIC. These elements correlate with major climatic events of the last millennium, such as the Medieval Warm Period (900-1300 AD) and the Little Ice Age (1450-1850 AD). 2) Pb and Cd are related to anthropogenic pollution and demonstrate industrial sourced trends throughout the anthropocene (since 1750 AD). 3) Terrogenous elements, including Fe, Al, Mn and V. Al in seawater and sediments has been used to trace water masses and land derived sediment source. We observe a major change in average vermetid Al/Fe ratios from 0.5 to 2.5 over the recorded period (n=72). This vermetid Al/Fe change points at a possible shift from Nilotic sediments (0.1-0.5 Al/Fe molar ratio) to Saharan dust ratio (2-4 Al/Fe molar ratio). Mn and V show a similar variability to Fe. Understanding the variability of vermetid TE can help us interpret the relative dominance of different climate systems and anthropogenic processes on the East Mediterranean environment.

Two novel macroacyclic schiff bases containing bis-N 2O 2 donor set and their binuclear complexes: synthesis, spectroscopic and magnetic properties

NASA Astrophysics Data System (ADS)

Karaoglu, Kaan; Baran, Talat; Serbest, Kerim; Er, Mustafa; Degirmencioglu, Ismail

2009-03-01

Herein, we report two novel macroacyclic Schiff bases derived from tetranaphthaldehyde derivative compound and their binuclear Mn(II), Ni(II), Cu(II) and Zn(II) complexes. The structures of the compounds have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H and 13C NMR, UV-Vis, electrospray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. The stoichiometries of the complexes derived from mass and elemental analysis correspond to the general formula [M 2L(ClO 4) n](ClO 4) 4-n, (where M is Mn(II), Ni(II), Cu(II), Zn(II) and L represents the Schiff base ligands).

Finite element analysis of stress distribution on the mandible and condylar fracture osteosynthesis during various clenching tasks.

PubMed

Hijazi, Loai; Hejazi, Wael; Darwich, Mhd Ayham; Darwich, Khaldoun

2016-12-01

The purpose of the study was to evaluate the effect of clenching tasks on the stress and strain of condylar osteosynthesis screws and plates, as well as on the stress, strain distribution and displacement on the whole mandible and bone surrounding screws. Three-dimensional finite element models of the mandible, two straight four-hole plates and eight screws were established. Six static clenching tasks were simulated in this study: incisal clench (INC), intercuspal position (ICP), right unilateral molar clench (RMOL), left unilateral molar clench (LMOL), right group function (RGF) and left group function (LGF). Based on the simulation of the six clenching tasks, none of the inserted screws and plates were broken or bended. For the whole mandibular bone, the maximum von Mises stress and von Mises strain observed were yielded by the ICP. For the bone surrounding the inserted screws, the maximum von Mises stress and von Mises strain were yielded by the LMOL (49.2 MPa and 3795.1 μ). Clenching tasks had significant effects on the stress distribution on the condylar osteosynthesis and the bone surrounding screws. Contralateral occlusion task (LMOL) had the maximal results of von Mises stress and strain and healing problems could be occur, this result confirms the importance of soft diet after surgery.

Synthesis, spectroscopic and antimicrobial studies of La(III), Ce(III), Sm(III) and Y(III) Metformin HCl chelates.

PubMed

Refat, Moamen S; Al-Azab, Fathi M; Al-Maydama, Hussein M A; Amin, Ragab R; Jamil, Yasmin M S; Kobeasy, Mohamed I

2015-05-05

Metal complexes of Metformin hydrochloride were prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes were discussed and synthesized to serve as potential insulin-mimetic. Some physical properties and analytical data of the four complexes were checked. The elemental analysis shows that La(III), Ce(III) Sm(III) and Y(III) formed complexes with Metformin in 1:3 (metal:MF) molar ratio. All the synthesized complexes are white and possess high melting points. These complexes are soluble in dimethylsulfoxide and dimethylformamide, partially soluble in hot methanol and insoluble in water and some other organic solvents. From the spectroscopic (infrared, UV-vis and florescence), effective magnetic moment and elemental analyses data, the formula structures are suggested. The results obtained suggested that Metformin reacted with metal ions as a bidentate ligand through its two imino groups. The molar conductance measurements proved that the Metformin complexes are slightly electrolytic in nature. The kinetic thermodynamic parameters such as: E(∗), ΔH(∗), ΔS(∗) and ΔG(∗) were estimated from the DTG curves. The antibacterial evaluations of the Metformin and their complexes were also performed against some gram positive, negative bacteria as well as fungi. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic, thermal and antimicrobial investigations of charge-transfer complexes formed from the drug procaine hydrochloride with quinol, picric acid and TCNQ

NASA Astrophysics Data System (ADS)

Adam, Abdel Majid A.

2012-12-01

Intermolecular charge-transfer or proton-transfer complexes between the drug procaine hydrochloride (PC-HCl) as a donor and quinol (QL), picric acid (PA) or 7,7',8,8'-tetracyanoquinodimethane (TCNQ) as a π-acceptor have been synthesized and spectroscopically studied in methanol at room temperature. Based on elemental analyses and photometric titrations, the stoichiometry of the complexes (donor:acceptor molar ratios) was determined to be 1:1 for all three complexes. The formation constant (KCT), molar extinction coefficient (ɛCT) and other spectroscopic data have been determined using the Benesi-Hildebrand method and its modifications. The newly synthesized CT complexes have been characterized via elemental analysis, IR, Raman, 1H NMR, and electronic absorption spectroscopy. The morphological features of these complexes were investigated using scanning electron microscopy (SEM), and the sharp, well-defined Bragg reflections at specific 2θ angles have been identified from the powder X-ray diffraction patterns. Thermogravimetric analyses (TGAs) and kinetic thermodynamic parameters were also used to investigate the thermal stability of the synthesized solid CT complexes. Finally, the CT complexes were screened for their antibacterial and antifungal activities against various bacterial and fungal strains, and only the complex obtained using picric acid exhibited moderate antibacterial activity against all of the tested strains.

Sub-10-Minute Characterization of an Ultrahigh Molar Mass Polymer by Multi-detector Hydrodynamic Chromatography

USDA-ARS?s Scientific Manuscript database

Molar mass averages, distributions, and architectural information of polymers are routinely obtained using size-exclusion chromatography (SEC). It has previously been shown that ultrahigh molar mass polymers may experience degradation during SEC analysis, leading to inaccurate molar mass averages a...

Mandibular canine intrusion with the segmented arch technique: A finite element method study.

PubMed

Caballero, Giselle Milagros; Carvalho Filho, Osvaldo Abadia de; Hargreaves, Bernardo Oliveira; Brito, Hélio Henrique de Araújo; Magalhães Júnior, Pedro Américo Almeida; Oliveira, Dauro Douglas

2015-06-01

Mandibular canines are anatomically extruded in approximately half of the patients with a deepbite. Although simultaneous orthodontic intrusion of the 6 mandibular anterior teeth is not recommended, a few studies have evaluated individual canine intrusion. Our objectives were to use the finite element method to simulate the segmented intrusion of mandibular canines with a cantilever and to evaluate the effects of different compensatory buccolingual activations. A finite element study of the right quadrant of the mandibular dental arch together with periodontal structures was modeled using SolidWorks software (Dassault Systèmes Americas, Waltham, Mass). After all bony, dental, and periodontal ligament structures from the second molar to the canine were graphically represented, brackets and molar tubes were modeled. Subsequently, a 0.021 × 0.025-in base wire was modeled with stainless steel properties and inserted into the brackets and tubes of the 4 posterior teeth to simulate an anchorage unit. Finally, a 0.017 × 0.025-in cantilever was modeled with titanium-molybdenum alloy properties and inserted into the first molar auxiliary tube. Discretization and boundary conditions of all anatomic structures tested were determined with HyperMesh software (Altair Engineering, Milwaukee, Wis), and compensatory toe-ins of 0°, 4°, 6°, and 8° were simulated with Abaqus software (Dassault Systèmes Americas). The 6° toe-in produced pure intrusion of the canine. The highest amounts of periodontal ligament stress in the anchor segment were observed around the first molar roots. This tooth showed a slight tendency for extrusion and distal crown tipping. Moreover, the different compensatory toe-ins tested did not significantly affect the other posterior teeth. The segmented mechanics simulated in this study may achieve pure mandibular canine intrusion when an adequate amount of compensatory toe-in (6°) is incorporated into the cantilever to prevent buccal and lingual crown tipping. The effects on the posterior anchorage segment were small and initially concentrated on the first molar. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

40 CFR Table A-7 to Subpart A of... - Data Elements That Are Inputs to Emission Equations and for Which the Reporting Deadline Is March...

Code of Federal Regulations, 2013 CFR

2013-07-01

... mass balance equation. K 98.116(b) Only annual production by product from each EAF (No CEMS). K 98.116... contributed by methane. Y 98.256(f)(7) Only molar volume conversion factor. Y 98.256(f)(10) Only coke burn-off... methane in coking gas. Y 98.256(l)(5) Only molar volume conversion factor. Y 98.256(m)(3) Only total...

Connector design in a long-span-fixed dental prosthesis: a three-dimensional finite element analysis.

PubMed

Harshitha Gowda, B H; Satish Babu, C L

2013-01-01

The goal of every prosthetic management is to simulate nature and be in harmony with nature within the physiological limits. The occlusal forces on a fixed dental prosthesis are transmitted to the surrounding structures through pontics, connectors and retainers and more stresses are seen at the connector region. To analyze the stress patterns in cast and soldered connectors between the two pontics and between the retainer and pontic of a four unit fixed dental prosthesis on axial and non axial loading and also to observe and ascertain the need to modify the design of the rigid connectors. Subsequently four models each of cast and soldered connectors with cylindrical and triangular design, of dimension 3 × 4 mm and thickness 0.5 mm was designed for the study. The first premolar and second molar were considered as the abutments and 2 nd premolar and 1 st molar as the pontics. The analysis was done using ANSYS version 8.0 software and by placing axial and non-axial load of 40 Newtons each. Von Misses stresses were observed at the connector region between the two pontics, especially in the cervical region. The cylindrical cast connectors showed less stress in comparison to triangular design and the difference in the stress distribution of cast and soldered connectors were marginal. The occlusal forces on a fixed dental prosthesis are transmitted to the surrounding structures through pontics, connectors and retainers with maximum stresses concentrated at the connectors. Hence this three-dimensional finite element analysis study investigated stress distribution in a four unit posterior fixed dental prosthesis, having cylindrical and triangular connector designs.

Using occlusal wear information and finite element analysis to investigate stress distributions in human molars

PubMed Central

Benazzi, Stefano; Kullmer, Ottmar; Grosse, Ian R; Weber, Gerhard W

2011-01-01

Simulations based on finite element analysis (FEA) have attracted increasing interest in dentistry and dental anthropology for evaluating the stress and strain distribution in teeth under occlusal loading conditions. Nonetheless, FEA is usually applied without considering changes in contacts between antagonistic teeth during the occlusal power stroke. In this contribution we show how occlusal information can be used to investigate the stress distribution with 3D FEA in lower first molars (M1). The antagonistic crowns M1 and P2–M1 of two dried modern human skulls were scanned by μCT in maximum intercuspation (centric occlusion) contact. A virtual analysis of the occlusal power stroke between M1 and P2–M1 was carried out in the Occlusal Fingerprint Analyser (OFA) software, and the occlusal trajectory path was recorded, while contact areas per time-step were visualized and quantified. Stress distribution of the M1 in selected occlusal stages were analyzed in strand7, considering occlusal information taken from OFA results for individual loading direction and loading area. Our FEA results show that the stress pattern changes considerably during the power stroke, suggesting that wear facets have a crucial influence on the distribution of stress on the whole tooth. Grooves and fissures on the occlusal surface are seen as critical locations, as tensile stresses are concentrated at these features. Properly accounting for the power stroke kinematics of occluding teeth results in quite different results (less tensile stresses in the crown) than usual loading scenarios based on parallel forces to the long axis of the tooth. This leads to the conclusion that functional studies considering kinematics of teeth are important to understand biomechanics and interpret morphological adaptation of teeth. PMID:21615398

FTIR, magnetic, 1H NMR spectral and thermal studies of some chelates of caproic acid: inhibitory effect on different kinds of bacteria.

PubMed

Refat, Moamen S; El-Korashy, Sabry A; Kumar, Deo Nandan; Ahmed, Ahmed S

2008-06-01

A convenient method for the preparation of complexes of the Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, ZrO2+, UO2(2+), Zr4+ and Th4+ ions with caproic acid (Hcap) is reported and this has enabled 10 complexes of caproate anion to be formulated: [Cr(cap)3].5H2O, [Mn(cap)2(H2O)2], [Fe(cap)3].12H2O, [Co(cap)2(H2O)2].4H2O, [Ni(cap)2(H2O)2].3H2O, [Zn(cap)2], [ZrO(cap)2].3H2O, [UO2(cap)(NO3)], [Zr(cap)2(Cl)2] and [Th(cap)4]. These new complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR and UV-vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. It has been found from the elemental analysis as well as thermal studies that the caproate ligand behaves as bidentate ligand and forming chelates with 1:1 (metal:ligand) stoichiometry for UO2(2+), 1:2 for (Mn2+, Co2+, Ni2+, Zn2+, ZrO2+ and Zr4+), 1:3 stoichiometry for (Cr3+ and Fe3+) and 1:4 for Th4+ caproate complexes, respectively, as bidentate chelating. The molar conductance measurements proved that the caproate complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The antibacterial activity of the caproic acid and their complexes was evaluated against some gram positive/negative bacteria.

Angulated Dental Implants in Posterior Maxilla FEA and Experimental Verification

PubMed Central

Hamed, Hamed A.; Marzook, Hamdy A.; Ghoneem, Nahed E.; El–Anwar, Mohamed I.

2018-01-01

AIM: This study aimed to evaluate the effect of different implant angulations in posterior maxilla on stress distribution by finite element analysis and verify its results experimentally. METHODS: Two simplified models were prepared for an implant placed vertically and tilted 25° piercing the maxillary sinus. Geometric models’ components were prepared by Autodesk Inventor then assembled in ANSYS for finite element analysis. The results of finite element analysis were verified against experimental trials results which were statistically analysed using student t-test (level of significance p < 0.05). RESULTS: Implant - abutment complex absorbed the load energy in case of vertical implant better than the case of angulated one. That was reflected on cortical bone stress, while both cases showed stress levels within the physiological limits. Comparing results between FEA and experiment trials showed full agreement. CONCLUSION: It was found that the tilted implant by 25° can be utilised in the posterior region maxilla for replacing maxillary first molar avoiding sinus penetration. The implant-bone interface and peri-implant bones received the highest Von Mises stress. Implant - bone interface with angulated implant received about 66% more stresses than the straight one. PMID:29531612

Evaluation of mandibular angle ostectomy using three-dimensional finite element analysis.

PubMed

Song, Jian; Zhu, Songsong; Luo, En; Hu, Jing; Feng, Ge

2014-07-01

This study was designed to investigate the stress and the displacement distributions of the mandible after mandibular angle ostectomy (MAO) by means of three-dimensional finite element analysis. On the basis of a female patient with a prominent angle of the mandible, the finite element models were generated by helical computed tomography and related software and were analyzed under muscle forces and 3 kinds of biting conditions, including intercuspal position (ICP), incisal clenching (INC), and right unilateral molar clenching (RMOL). The mandibular stress and displacement distributions were analyzed by Abaqus software. In the model of MAO, the increased stress and the decreased displacement was found in ICP, INC, and RMOL at the area of mandibular angle. The stress and the displacement increased in ICP and RMOL, whereas the others remained unchanged in INC at the area of mandibular condylar neck. The results of this study have shown that MAO could alter biomechanical characteristics in the operated mandible, which suggested that a greater hit on face may lead to a higher incidence rate of condyle fracture and a lower incidence rate of angle fracture after MAO.

Immediate versus conventional loading of implant-supported maxillary overdentures: a finite element stress analysis.

PubMed

Akca, Kivanc; Eser, Atilim; Eckert, Steven; Cavusoglu, Yeliz; Cehreli, Murat Cavit

2013-01-01

To compare biomechanical outcomes of immediately and conventionally loaded bar-retained implant-supported maxillary overdentures using finite element stress analysis. Finite element models were created to replicate the spatial positioning of four 4.1 × 12-mm implants in the completely edentulous maxillae of four cadavers to support bar-retained overdentures with 7-mm distal extension cantilevers. To simulate the bone-implant interface of immediately loaded implants, a contact situation was defined at the interface; conventional loading was simulated by "bonding" the implants to the surrounding bone. The prostheses were loaded with 100 N in the projected molar regions bilaterally, and strain magnitudes were measured at the buccal aspect of bone. The amplitude of axial and lateral strains, the overall strain magnitudes, and the strain magnitudes around anterior and posterior implants in the immediate loading group were comparable to those seen in the conventional loading group, suggesting that the loading regimens created similar stress/strain fields (P > .05). Conventional and immediate loading of maxillary implants supporting bar-retained overdentures resulted in similar bone strains.

Real-time measurement of size-resolved elemental composition ratio for flame synthesized composite nanoparticle aggregates using a tandem SMPS-ICP-OES

PubMed Central

Reed, Nathan; Fang, Jiaxi; Chavalmane, Sanmathi; Biswas, Pratim

2017-01-01

Composite nanoparticles find application in catalysis, drug delivery, and energy storage and require increasingly fine control of their physical properties and composition. While composite nanoparticles have been widely synthesized and characterized, little work has systematically correlated the initial concentration of precursors and the final composition of flame synthesized composite nanoparticles. This relationship is explored in a diffusion flame aerosol reactor by coupling a scanning mobility particle sizer (SMPS) with an inductively coupled plasma optical emission spectrometer (ICP-OES). A framework for studying the relationship between the initial precursor concentrations of different elements and the final nanoparticle composition is explored. The size-resolved elemental composition was measured by directly injecting size-selected fractions of aggregated magnetite and silicon dioxide composite nanoparticles into the ICP-OES plasma. This work showed a correlation between precursor molar ratio and the measured elemental ratio in the mobility size range of 50 to 140 nm. Building on previous work studying size resolved elemental composition of engineered nanoparticles, the analysis is extended to flame synthesized composite nanoparticle aggregates in this work. PMID:28435179

Real-time measurement of size-resolved elemental composition ratio for flame synthesized composite nanoparticle aggregates using a tandem SMPS-ICP-OES.

PubMed

Reed, Nathan; Fang, Jiaxi; Chavalmane, Sanmathi; Biswas, Pratim

2017-01-01

Composite nanoparticles find application in catalysis, drug delivery, and energy storage and require increasingly fine control of their physical properties and composition. While composite nanoparticles have been widely synthesized and characterized, little work has systematically correlated the initial concentration of precursors and the final composition of flame synthesized composite nanoparticles. This relationship is explored in a diffusion flame aerosol reactor by coupling a scanning mobility particle sizer (SMPS) with an inductively coupled plasma optical emission spectrometer (ICP-OES). A framework for studying the relationship between the initial precursor concentrations of different elements and the final nanoparticle composition is explored. The size-resolved elemental composition was measured by directly injecting size-selected fractions of aggregated magnetite and silicon dioxide composite nanoparticles into the ICP-OES plasma. This work showed a correlation between precursor molar ratio and the measured elemental ratio in the mobility size range of 50 to 140 nm. Building on previous work studying size resolved elemental composition of engineered nanoparticles, the analysis is extended to flame synthesized composite nanoparticle aggregates in this work.

Polysaccharide characterization by hollow-fiber flow field-flow fractionation with on-line multi-angle static light scattering and differential refractometry.

PubMed

Pitkänen, Leena; Striegel, André M

2015-02-06

Accurate characterization of the molar mass and size of polysaccharides is an ongoing challenge, oftentimes due to architectural diversity but also to the broad molar mass (M) range over which a single polysaccharide can exist and to the ultra-high M of many polysaccharides. Because of the latter, many of these biomacromolecules experience on-column, flow-induced degradation during analysis by size-exclusion and, even, hydrodynamic chromatography (SEC and HDC, respectively). The necessity for gentler fractionation methods has, to date, been addressed employing asymmetric flow field-flow fractionation (AF4). Here, we introduce the coupling of hollow-fiber flow field-flow fractionation (HF5) to multi-angle static light scattering (MALS) and differential refractometry (DRI) detection for the analysis of polysaccharides. In HF5, less stresses are placed on the macromolecules during separation than in SEC or HDC, and HF5 can offer a higher sensitivity, with less propensity for system overloading and analyte aggregation, than generally found in AF4. The coupling to MALS and DRI affords the determination of absolute, calibration-curve-independent molar mass averages and dispersities. Results from the present HF5/MALS/DRI experiments with dextrans, pullulans, and larch arabinogalactan were augmented with hydrodynamic radius (RH) measurements from off-line quasi-elastic light scattering (QELS) and by RH distribution calculations and fractogram simulations obtained via a finite element analysis implementation of field-flow fractionation theory by commercially available software. As part of this study, we have investigated analyte recovery in HF5 and also possible reasons for discrepancies between calculated and simulated results vis-à-vis experimentally determined data. Published by Elsevier B.V.

Synthesis, characterization, thermal and biological evaluation of Cu (II), Co (II) and Ni (II) complexes of azo dye ligand containing sulfamethaxazole moiety

NASA Astrophysics Data System (ADS)

Mallikarjuna, N. M.; Keshavayya, J.; Maliyappa, M. R.; Shoukat Ali, R. A.; Venkatesh, Talavara

2018-08-01

A novel bioactive Cu (II), Co (II) and Ni (II) complexes of the azo dye ligand (L) derived from sulfamethoxazole were synthesized. The structures of the newly synthesized compounds were characterized by elemental analysis, molar conductance, magnetic susceptibility, FTIR, UV-visible, 1H NMR, mass, thermal and powder XRD spectral techniques. Molar conductivity measurements in DMSO solution confirmed the non-electrolytic nature of the complexes. All the synthesized metal complexes were found to be monomeric and showed square planar geometry except the Co (II) complex which has six coordinate, octahedral environment. The metal complexes have exhibited potential growth inhibitory effect against tested bacterial strains as compared to the free ligand. The ligand and complexes have also shown significant antioxidant and Calf Thymus DNA cleavage activities. Further, the in silico molecular docking studies were performed to predict the possible binding sites of the ligand (L) and its metal complexes with target receptor Glu-6P.

Mineralization of mandibular third molars can estimate chronological age--Brazilian indices.

PubMed

de Oliveira, Fernando Toledo; Capelozza, Ana Lúcia Álvares; Lauris, José Roberto Pereira; de Bullen, Izabel Regina Fischer Rubira

2012-06-10

Forensic age estimation is an important element of anthropological research, as it produces one of the primary sources of data that researchers use to establish the identity of a person living or the identity of unknown bodily remains. The aim of this study was to determine if the chronology of third molar mineralization could be an accurate indicator of estimated age in a sample Brazilian population. If so, mineralization could determine the probability of an individual being 18 years or older. The study evaluated 407 panoramic radiographs of males and females from the past 5 years in order to assess the mineralization status of the mandibular third molars. The evaluation was carried out using an adaptation of Demirjian's system. The results indicated a strong correlation between chronological age and the mineralization of the mandibular third molars. The results indicated that modern Brazilian generation tends to demonstrate an earlier mandibular third molar mineralization than older Brazilian generation and people of other nationalities. Males reached developmental stages slightly earlier than females, but statistically significant differences between the sex were not found. The probability that an individual with third molar mineralization stage H had reached an age of 18 years or older was 96.8-98.6% for males and females, respectively. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Synthesis, characterization and cytotoxicity of rare earth metal ion complexes of N,N‧-bis-(2-thiophenecarboxaldimine)-3,3‧-diaminobenzidene, Schiff base ligand

NASA Astrophysics Data System (ADS)

Shakir, Mohammad; Abbasi, Ambreen; Faraz, Mohammad; Sherwani, Asif

2015-12-01

Lanthanide complexes of La3+, Pr3+, Nd3+, Gd3+, Er3+ of general formula [Ln2 L(H2O)4(NO3)4](NO3)2·2H2O have been synthesized from Schiff base, N,N‧-bis-(2-thiophenecarboxaldimine)-3,3‧-diaminobenzidene. The complexes were characterized by elemental analysis, molar conductance, UV-Vis, fluorescence, FT-IR,1H NMR, mass spectroscopy, EDX, SEM and thermal analysis. FT-IR spectral data suggested that ligand coordinate with metal ions through azomethine nitrogen and uncondensed amino group. Molar conductance data revealed 1:2 electrolytic nature of complexes. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (ligand:metal). Thephysico-chemical data suggested eight coordination number for Ln(III)Schiffbase complexes. SEM analysis shows morphological changes in the surfaces of complexes as compared to free ligand. Thermal decomposition profiles were consistent with proposed formulations. The anticancer activity of the complexes and theSchiffbase ligand has been studied towards human cervical cancer celllines (HeLa) and human breast cancer cell lines (MCF-7) and it was found that complexes exhibited greater activity than theSchiffbase.

Continuous-flow biosynthesis of Au-Ag bimetallic nanoparticles in a microreactor

NASA Astrophysics Data System (ADS)

Liu, Hongyu; Huang, Jiale; Sun, Daohua; Odoom-Wubah, Tareque; Li, Jun; Li, Qingbiao

2014-11-01

Herein, a microfluidic biosynthesis of Au-Ag bimetallic nanoparticle (NP) in a tubular microreactor, based on simultaneous reduction of HAuCl4 and AgNO3 precursors in the presence of Cacumen Platycladi ( C. Platycladi) extract was studied. The flow velocity profile was numerically analyzed with computational fluid dynamics. Au-Ag bimetallic NPs with Ag/Au molar ratios of 1:1 and 2:1 were synthesized, respectively. The alloy formation, morphology, structure, and size were investigated by UV-Vis spectra analysis, transmission electron microscopy (TEM), high resolution TEM, scanning TEM, and energy-dispersive X-ray analysis. In addition, the effects of volumetric flow rate, reaction temperature, and concentration of C. Platycladi extract and NaOH on the properties of the as-synthesized Au-Ag bimetallic NPs were investigated. The results indicated that these factors could not only affect the molar ratios of the two elements in the Au-Ag bimetallic NPs, but also affect particle size which can be adjusted from 3.3 to 5.6 nm. The process was very rapid and green, since a microreactor was employed with no additional synthetic reagents used. This work is anticipated to provide useful parameters for continuous-flow biosynthesis of bimetallic NPs in microreactors.

Dental stigmata and enamel thickness in a probable case of congenital syphilis from XVI century Croatia.

PubMed

Lauc, Tomislav; Fornai, Cinzia; Premužić, Zrinka; Vodanović, Marin; Weber, Gerhard W; Mašić, Boris; Rajić Šikanjić, Petra

2015-10-01

To analyse the dental remains of an individual with signs of congenital syphilis by using macroscopic observation, CBCT and micro-CT images, and the analysis of the enamel thickness. Anthropological analysis of human skeletal remains from the 16th century archaeological site Park Grič in Zagreb, Croatia discovered a female, 17-20 years old at the time of death, with dental signs supportive of congenital syphilis: mulberry molars and canine defects, as well as non-specific hypoplastic changes on incisors. The focus of the analysis was on three aspects: gross morphology, hypoplastic defects of the molars, canines and incisors, as well as enamel thickness of the upper first and second molars. The observed morphology of the first molars corresponds to the typical aspect of mulberry molars, while that of the canines is characterised by hypomineralisation. Hypoplastic grooves were observed on the incisal edges of all incisors. The enamel of the first molars is underdeveloped while in the second molars a thick-enamelled condition is observed. Our observations for the dental and skeletal evidence are supportive to a diagnosis of congenital syphilis for this specimen from XVI century Croatia. The use of CT imaging helped documenting the diagnostic features and quantifying the effect of the dental stigmata on first molars. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis, characterization and in vitro anticancer activity of 18-membered octaazamacrocyclic complexes of Co(II), Ni(II), Cd(II) and Sn(II)

NASA Astrophysics Data System (ADS)

Kareem, Abdul; Zafar, Hina; Sherwani, Asif; Mohammad, Owais; Khan, Tahir Ali

2014-10-01

An effective series of 18 membered octaazamacrocyclic complexes of the type [MLX2], where X = Cl or NO3 have been synthesized by template condensation reaction of oxalyl dihydrazide with dibenzoylmethane and metal salt in 2:2:1 molar ratio. The formation of macrocyclic framework, stereochemistry and their overall geometry have been characterized by various physico-chemical studies viz., elemental analysis, electron spray ionization-mass spectrometry (ESI-MS), I.R, UV-Vis, 1H NMR, 13C NMR spectroscopy, X-ray diffraction (XRD) and TGA/DTA studies. These studies suggest formation of octahedral macrocyclic complexes of Co(II), Ni(II), Cd(II) and Sn(II). The molar conductance values suggest nonelectrolytic nature for all the complexes. Thermogravimatric analysis shows that all the complexes are stable up to 600 °C. All these complexes have been tested against different human cancer cell lines i.e. human hepatocellular carcinoma (Hep3B), human cervical carcinoma (HeLa), human breast adenocarcinoma (MCF7) and normal cells (PBMC). The newly synthesized 18-membered octaazamacrocyclic complexes during in vitro anticancer evaluation, displayed moderate to good cytotoxicity on liver (Hep3B), cervical (HeLa) and breast (MCF7) cancer cell lines, respectively. The most effective anticancer cadmium complex (C34H28N10CdO10) was found to be active with IC50 values, 2.44 ± 1.500, 3.55 ± 1.600 and 4.82 ± 1.400 in micro-molar on liver, cervical and breast cancer cell lines, respectively.

New Design for an Adjustable Cise Space Maintainer

PubMed Central

2018-01-01

Objective The aim of this study is to present a new adjustable Cise space maintainer for preventive orthodontic applications. Methods Stainless steel based new design consists of six main components. In order to understand the major displacement and stress fields, structural analysis for the design is considered by using finite element method. Results Similar to major displacement at y-axis, critical stresses σx and τxy possess a linear distribution with constant increasing. Additionally, strain energy density (SED) plays an important role to determine critical biting load capacity. Conclusion Structural analysis shows that the space maintainer is stable and is used for maintaining and/or regaining the space which arouses early loss of molar tooth. PMID:29854764

Synthesis, characterization and biological activities of copper(II) complex of 2-Benzimidazolyl-urea and the nitrate salt of 2-Benzimidazolyl-urea

NASA Astrophysics Data System (ADS)

Poyraz, Mehmet; Sari, Musa; Banti, Christina N.; Hadjikakou, Sotiris K.

2017-10-01

The synthesis of the complex {[Cu(BZIMU)2](NO3)2} (1) (BZIMU = 2-Benzimidazolyl-urea) is reported here. The complex 1 was characterized by elemental analysis, FT-IR, magnetic susceptibility and molar conductance measurements. The crystal structures of 1 and of the nitrate salt of [(BZIMUH+)(NO3)-] (2) were determined by X-ray diffraction analysis. The copper complex 1 and [(BZIMUH+)(NO3)-] (2) were evaluated for their in vitro cytotoxic activity (cell viability) against human cervix adenocarcinoma (HeLa) and human breast adenocarcinoma (MCF-7) cell line and normal human fetal lung fibroblast cells (MRC-5) with SRB assay.

Radiographic evaluation of third molar development in 6- to 24-year-olds

PubMed Central

Jung, Yun-Hoa

2014-01-01

Purpose This study investigated the developmental stages of third molars in relation to chronological age and compared third molar development according to location and gender. Materials and Methods A retrospective analysis of panoramic radiographs of 2490 patients aged between 6 and 24 years was conducted, and the developmental stages of the third molars were evaluated using the modified Demirjian's classification. The mean age, standard deviation, minimal and maximal age, and percentile distributions were recorded for each stage of development. A Mann-Whitney U test was performed to test the developmental differences in the third molars between the maxillary and mandibular arches and between genders. A linear regression analysis was used for assessing the correlation between the third molar development and chronological age. Results The developmental stages of the third molars were more advanced in the maxillary arch than the mandibular arch. Males reached the developmental stages earlier than females. The average age of the initial mineralization of the third molars was 8.57 years, and the average age at apex closure was 21.96 years. The mean age of crown completion was 14.52 and 15.04 years for the maxillary and the mandibular third molars, respectively. Conclusion The developmental stages of the third molars clearly showed a strong correlation with age. The third molars developed earlier in the upper arch than the lower arch; further, they developed earlier in males than in females. PMID:25279338

Age estimation using development of third molars in South Indian population: A radiological study.

PubMed

Priyadharshini, K Indra; Idiculla, Jose Joy; Sivapathasundaram, B; Mohanbabu, V; Augustine, Dominic; Patil, Shankargouda

2015-05-01

To assess the estimation of chronological age based on the stages of third molar development following the eight stages (A-H) method of Demirjian et al. in Chennai population of South India. A sample consisting of 848 individuals (471 males and 377 females) aged between 14 and 30 years was randomly selected for the clinical evaluation and 323 orthopantomograms with clinically missing third molars were taken for radiological evaluation using Demirjian's method from a Chennai population of known chronological age and sex. Statistical analysis was performed using Pearson's Chi-square test and mean values were compared between the study groups using t-test or analysis of variance (ANOVA) followed by Tukey's highly significant difference (HSD). In the present study, P < 0.05 was considered as the level of significance. The results showed that the mean age of having clinically completely erupted maxillary third molars was 22.41 years in male subjects and 23.81 years in female subjects and that of mandibular third molars was 21.49 years in male subjects and 23.34 years in female subjects. Mandibular third molars were clinically missing more often in females than in males. Eruption of mandibular third molars was generally ahead of the emergence of maxillary third molars into the oral cavity. Third molar development between male and female subjects showed statistically significant differences at calcification stage F and stage G in maxillary third molars and stage F in mandibular third molars (P < 0.05). There are differences indicating that maxillary and mandibular third molar eruption reached Demirjian's formation stages earlier in males than in females. It is suggested that in future studies, to increase the accuracy of age determination, indications of sexual maturity and ossification should also be evaluated in addition to third molar mineralization.

Synthesis of copper nanocolloids using a continuous flow based microreactor

NASA Astrophysics Data System (ADS)

Xu, Lei; Peng, Jinhui; Srinivasakannan, C.; Chen, Guo; Shen, Amy Q.

2015-11-01

The copper (Cu) nanocolloids were prepared by sodium borohydride (NaBH4) reduction of metal salt solutions in a T-shaped microreactor at room temperature. The influence of NaBH4 molar concentrations on copper particle's diameter, morphology, size distribution, and elemental compositions has been investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The ultraviolet-visible spectroscopy (UV-vis) was used to verify the chemical compounds of nanocolloids and estimate the average size of copper nanocolloids. The synthesized copper nanocolloids were uniform in size and non-oxidized. A decrease in the mean diameter of copper nanocolloids was observed with increasing NaBH4 molar concentrations. The maximum mean diameter (4.25 nm) occurred at the CuSO4/NaBH4 molar concentration ratio of 1:2.

A radiographic survey of agenesis of the third molar: A panoramic study

PubMed Central

Singh, Nisha; Chaudhari, Shrinivas; Chaudhari, Rohan; Nagare, Sagar; Kulkarni, Abhay; Parkarwar, Pratik

2017-01-01

Purpose: It is a well-known fact that nature tries to eliminate what is not in use. Because of this, the number of certain teeth which are no longer necessary for function are either getting increasingly impacted or are not developing at all. This is especially the case where third molars are concerned. Furthermore, the presence or absence of the third molar is significant to all branches of dentistry and in particular, forensic dentistry. Objectives: The objectives of this study is to assess (1) The prevalence of third molar agenesis in population of age group 18–25 years. (2) The genderwise difference of third molar agenesis. (3) The difference between maxilla and mandible. Materials and Methods: Dental patients, who are advised or referred for orthopantomograph, visited to the Department of Oral Medicine and Radiology were included in the study. The study population comprised 300 patients. Statistical Analysis: The data obtained was tabulated and subjected to statistical analysis. SPSS version 17 software was used for the analysis of the data. The Chi-square test was used for the same. Results: The incidence of agenesis of the third molar is significantly higher for tooth number 18 (P < 0.001). Overall, it is significantly higher among females compared to the males (P < 0.001) in our study population. Conclusion: (1) The present study reports 46.7% agenesis of the third molar. (2) The frequency of third molar agenesis was found significantly greater in the females. (3) Third molar agenesis showed a greater predilection in maxilla compared to mandible. PMID:29657489

Finite element analysis of rapid canine retraction through reducing resistance and distraction

PubMed Central

XUE, Junjie; YE, Niansong; YANG, Xin; WANG, Sheng; WANG, Jing; WANG, Yan; LI, Jingyu; MI, Congbo; LAI, Wenli

2014-01-01

Objective The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis. Material and Methods Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises) stress and maximum shear stress. Results The maximum value of total deformation with the three kinds of models occurred in the distal part of the canine crown and gradually reduced from the crown to the apex of the canine; compared with the canines in model 3 and model 1, the canine in model 2 had the maximum value of displacement, up to 1.9812 mm. The lowest equivalent (von Mises) stress and the lowest maximum shear stress were concentrated mainly on the distal side of the canine root in model 2. The distribution of equivalent (von Mises) stress and maximum shear stress on the PDL of the canine in the three models was highly concentrated on the distal edge of the canine cervix. Conclusions Removal of the bone in the pathway of canine retraction results in low stress intensity for canine movement. Periodontal distraction aided by surgical undermining of the interseptal bone would reduce resistance and effectively accelerate the speed of canine retraction. PMID:24626249

Synthesis, spectroscopic, thermogravimetric and antimicrobial studies of mixed ligands complexes

NASA Astrophysics Data System (ADS)

Mahmoud, Walaa H.; Mahmoud, Nessma F.; Mohamed, Gehad G.; El-Sonbati, Adel Z.; El-Bindary, Ashraf A.

2015-09-01

An interesting series of mixed ligand complexes have been synthesized by the reaction of metal chloride with guaifenesin (GFS) in the presence of 2-aminoacetic acid (HGly) (1:1:1 molar ratio). The elemental analysis, magnetic moments, molar conductance, spectral (UV-Vis, IR, 1H NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structure of GFS is optimized theoretically and the quantum chemical parameters are calculated. The IR showed that the ligand (GFS) acts as monobasic tridentate through the hydroxyl, phenoxy etheric and methoxy oxygen atoms and co-ligand (HGly) as monobasic bidentate through the deprotonated carboxylate oxygen atom and nitrogen atom of amino group. The molar conductivities showed that all the complexes are non-electrolytes except Cr(III) complex is electrolyte. Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectrum for Cu(II) revealed data which confirm the proposed structure. Antibacterial screening of the compounds were carried out in vitro on gram positive (Bacillus subtilis and Staphylococcus aureus), gram negative (Escherichia coli and Neisseria gonorrhoeae) bacteria and for in vitro antifungal activity against Candida albicans organism. However, some complexes showed more chemotherapeutic efficiency than the parent GFS drug. The complexes were also screened for their in vitro anticancer activity against the breast cell line (MFC7) and the results obtained showed that they exhibit a considerable anticancer activity.

[Three-dimensional finite analysis of the stress in first mandibular molar with composite class I restoration when various mixing ratios of bases were used].

PubMed

Zhou, Lan; Yang, Jin-Bo; Liu, Dan; Liu, Zhan; Chen, Ying; Gao, Bo

2008-06-01

To analyze the possible damage to the remaining tooth and composite restorations when various mixing ratios of bases were used. Testing elastic modulus and poission's ratio of glass-ionomer Vitrebond and self-cured calcium hydroxide Dycal with mixing ratios of 1:1, 3:4, 4:3. Micro-CT was used to scan the first mandibular molar, and the three-dimensional finite element model of the first permanent mandibular molar with class I cavity was established. Analyzing the stress of tooth structure, composite and base cement under physical load when different mixing ratios of base cement were used. The elastic modulus of base cement in various mixing ratios was different, which had the statistic significance. The magnitude and location of stress in restored tooth made no differences when the mixing ratios of Vitrebond and Dycal were changed. The peak stress and spreading area in the model with Dycal was more than that with Vitrebond. Changing the best mixing ratio of base cement can partially influence the mechanistic character, but make no differences on the magnitude and location of stress in restored tooth. During the treatment of deep caries, the base cement of the elastic modulus which is proximal to the dentin and restoration should be chosen to avoid the fracture of tooth or restoration.

Synthesis and characterization of lead sulphide thin films from ethanolamine (ETA) complexing agent chemical bath

NASA Astrophysics Data System (ADS)

Gashaw Hone, Fekadu; Dejene, F. B.

2018-02-01

Polycrystalline lead sulphide (PbS) thin films were grown on glass substrates by chemical bath deposition route using ethanolamine (ETA) as a complexing agent. The effects of ETA molar concentration on the structural, morphological, electrical and optical properties of lead sulphide thin films were thoroughly studied. The XRD analyses revealed that all the deposited thin films were face center cubic crystal structure and their preferred orientations were varied along the (111) and (200) planes. The XRD results further confirmed that ETA concentration had a significant effects on the strain, average crystalline size and dislocation density of the deposited thin films. The SEM studies illustrated the evolution and transformation of surface morphology as ETA molar concentration increased from 0.41 M to 1.64 M. The energy dispersive x-ray analysis was used to verify the compositional elements of the deposited thin films. Optical spectroscopy investigation established that the band gap of the PbS thin films were reduced from 0.98 eV to 0.68 eV as ETA concentration increased. The photoluminescence spectra showed a well defined peak at 428 nm and shoulder around 468 nm for all PbS thin films. The electrical resistivity of the thin films found in the order of 103 Ω cm at room temperature and decreased as the ETA molar concentration was increased.

An original micro-CT study and meta-analysis of the internal and external anatomy of maxillary molars - implications for endodontic treatment.

PubMed

Tomaszewska, Iwona M; Jarzębska, Anna; Skinningsrud, Bendik; Pękala, Przemysław A; Wroński, Sebastian; Iwanaga, Joe

2018-05-07

The aim of this work was to conduct a radiological micro-CT study and meta-analysis to determine the morphological features of the root canal anatomy of the maxillary molars. The radiological study included micro-CT scans of 110 maxillary first molars and 98 maxillary second molars. To identify articles eligible for inclusion in our meta-analysis, PubMed, Embase, and Web of Science were search comprehensively. The following data were extracted: study type (cadaveric, intraoperative or imaging), Vertucci types of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and inter-canal communications. The mesiobuccal root was the most variable with respect to canal configuration, type I being the most common configuration followed by type II and type IV. Type I was the most common canal configuration in the distobuccal and palatal root. Regarding the number of canals in the maxillary first and second molars, one canal was most prevalent in all roots of the three molars, except for the mesiobuccal root of maxillary first molar, in which two canals were most prevalent. The most prevalent number of roots in all maxillary molars was three. Knowledge of endodontic anatomy determines the parameters of root canal treatment and significantly affects the probability of success. It is therefore especially important to know the morphology of the root canal system in order to perform endodontic treatment correctly. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Selenium and mercury molar ratios in saltwater fish from New Jersey: Individual and species variability complicate use in human health fish consumption advisories☆

PubMed Central

Burger, Joanna; Gochfeld, Michael

2014-01-01

Balancing risk versus benefits to humans and other organisms from consuming fish is a national concern in the USA, as well as in many other parts of the world. Protecting public health is both a federal and state responsibility, and states respond by issuing fish consumption advisories, particularly for mercury. Recently it has been emphasized that the protective role of selenium against mercury toxicity depends on their molar ratios, which should be evaluated as an indication of selenium’s protective capacity, and incorporated in risk assessments for fish consumption. However, there is no single “protective” ratio agreed upon. In this paper we examine the selenium:mercury (Se:Hg) molar ratios in a wide range of saltwater fish caught and eaten by recreational fishers along the New Jersey coast. We were particularly interested in interspecific and intraspecific variability, and whether the molar ratios were consistent within a species, allowing for its use in managing risk. The selenium–mercury molar ratio showed significant variation among and within fish species. The molar ratio decreased with the size of the fish species, decreased with the mercury levels, and within a fish species, the selenium:mercury ratio decreased with fish size. As an essential element, selenium undergoes some homeostatic regulation, but it is also highly toxic. Within species, mercury level tends to increase with size, accounting for the negative relationship between size and ratio. This variability may make it difficult to use the selenium:mercury molar ratio in risk assessment, risk management, and risk communication at this time, and more information is needed on how mercury and selenium actually interact and on the relationship between the molar ratios and health outcomes. PMID:22405995

Selenium and mercury molar ratios in saltwater fish from New Jersey: individual and species variability complicate use in human health fish consumption advisories.

PubMed

Burger, Joanna; Gochfeld, Michael

2012-04-01

Balancing risk versus benefits to humans and other organisms from consuming fish is a national concern in the USA, as well as in many other parts of the world. Protecting public health is both a federal and state responsibility, and states respond by issuing fish consumption advisories, particularly for mercury. Recently it has been emphasized that the protective role of selenium against mercury toxicity depends on their molar ratios, which should be evaluated as an indication of selenium's protective capacity, and incorporated in risk assessments for fish consumption. However, there is no single "protective" ratio agreed upon. In this paper we examine the selenium:mercury (Se:Hg) molar ratios in a wide range of saltwater fish caught and eaten by recreational fishers along the New Jersey coast. We were particularly interested in interspecific and intraspecific variability, and whether the molar ratios were consistent within a species, allowing for its use in managing risk. The selenium-mercury molar ratio showed significant variation among and within fish species. The molar ratio decreased with the size of the fish species, decreased with the mercury levels, and within a fish species, the selenium:mercury ratio decreased with fish size. As an essential element, selenium undergoes some homeostatic regulation, but it is also highly toxic. Within species, mercury level tends to increase with size, accounting for the negative relationship between size and ratio. This variability may make it difficult to use the selenium:mercury molar ratio in risk assessment, risk management, and risk communication at this time, and more information is needed on how mercury and selenium actually interact and on the relationship between the molar ratios and health outcomes. Copyright © 2012 Elsevier Inc. All rights reserved.

Synthesis, spectroscopic characterization and biological activities of N4O2 Schiff base ligand and its metal complexes of Co(II), Ni(II), Cu(II) and Zn(II)

NASA Astrophysics Data System (ADS)

Al-Resayes, Saud I.; Shakir, Mohammad; Abbasi, Ambreen; Amin, Kr. Mohammad Yusuf; Lateef, Abdul

The Schiff base ligand, bis(indoline-2-one)triethylenetetramine (L) obtained from condensation of triethylenetetramine and isatin was used to synthesize the complexes of type, [ML]Cl2 [M = Co(II), Ni(II), Cu(II) and Zn(II)]. L was characterized on the basis of the results of elemental analysis, FT-IR, 1H and 13C NMR, mass spectroscopic studies. The stoichiometry, bonding and stereochemistries of complexes were ascertained on the basis of results of elemental analysis, magnetic susceptibility values, molar conductance and various spectroscopic studies. EPR, UV-vis and magnetic moments revealed an octahedral geometry for complexes. L and its Cu(II) and Zn(II) complexes were screened for their antibacterial activity. Analgesic activity of Cu(II) and Zn(II) complexes was also tested in rats by tail flick method. Both complexes were found to possess good antibacterial and moderate analgesic activity.

Molar Functional Relations and Clinical Behavior Analysis: Implications for Assessment and Treatment

ERIC Educational Resources Information Center

Waltz, Thomas J.; Follette, William C.

2009-01-01

The experimental analysis of behavior has identified several molar functional relations that are highly relevant to clinical behavior analysis. These include matching, discounting, momentum, and variability. Matching provides a broader analysis of how multiple sources of reinforcement influence how individuals choose to allocate their time and…

Accumulation of trace elements used in semiconductor industry in Formosan squirrel, as a bio-indicator of their exposure, living in Taiwan.

PubMed

Suzuki, Yoshinari; Watanabe, Izumi; Oshida, Tatsuo; Chen, Yen-Jean; Lin, Liang-Kong; Wang, Yu-Huang; Yang, Kouh-Cheng; Kuno, Katsuji

2007-07-01

Concentrations of 17 trace elements were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) in Formosan squirrels (Callosciurus erythraeus) of Taiwan and Japan to document trace element pollution in Taiwan. High concentrations of elements used to produce semiconductors - Ga, As, Cd, In and Tl - were found in animals captured in Miaoli County, which is the nearest site to Hsinchu City, a chief city of Taiwan's semiconductor industry. Significant correlations between Ga, As, In and Tl were found in the kidney, liver, lung and muscle tissues of Taiwanese squirrels. Hierarchical cluster analysis indicated that Ga, As, In and Tl were of the same clade, indicating that Ga, As, In and Tl were discharged from an identical origin. Molar ratios of Ga/As concentration in lungs of animals captured in Miaoli resembled those of animals after intratracheal administration of particulate gallium arsenide (GaAs). This result might indicate that the higher concentrations of Ga and As in the specimens in Miaoli resulted from atmospheric exposure to GaAs.

Synthetic, Spectroscopic and Biocidal Aspects of Heterobimetallic Complexes Comprising Platinum(II) and a Group Four or Fourteen Element

PubMed Central

Sharma, Kripa

2000-01-01

Heterobimetallic complexes with varying amines have been synthesized by the reaction of [Pt(C2H8N2)2]Cl2 with group four or fourteen organometallic dichlorides, viz., R2MCl2 and Cp2M'Cl2 in a 1:2 molar ratio in MeOH (where M=Si or Sn, M'= Ti or Zr and R=Ph or Me). These complexes have been characterized by elemental analysis, molecular weight determinations, magnetic measurements, conductance, IR, 1H NMR and electronic spectra. The spectral data suggest a square planar geometry for all the complexes. Conductivity data suggest that they behave as electrolytes. These monometallic precursors along with their complexes have been screened in vitro against a number of pathogenic fungi and bacteria to assess their growth inhibiting potential. PMID:18475917

High-resolution nuclear microprobe elemental mapping of teeth enamel-dentine interface exposed to acidic conditions

NASA Astrophysics Data System (ADS)

Pineda-Vargas, C. A.; Eisa, M. E.; Chikte, U. M. E.; Conradie, J. L.

2004-10-01

The process of demineralisation in tooth erosion due to exposure to acidic media was investigated in a group of test and control healthy human molar teeth. Analysis by micro-PIXE and proton-backscattering showed that the levels of trace elements were enriched and/or depleted according to experimental treatment. The atomic ratios of major constituents in the matrix were characteristic of test or controls with typical ratios: O 5P 1Ca 3F 1 for tests and O 6P 0.5Ca 3F 0.5 for controls. The correlation between maps of Ca and Zn in and around the interface between dentine and enamel in control samples showed two kinds of correlation strengths (for enamel and dentine). The strongest correlation was related to the enamel area.

Effect of Intestinal Tapeworm Clestobothrium crassiceps on Concentrations of Toxic Elements and Selenium in European Hake Merluccius merluccius from the Gulf of Lion (Northwestern Mediterranean Sea).

PubMed

Torres, Jordi; Eira, Catarina; Miquel, Jordi; Ferrer-Maza, Dolors; Delgado, Eulàlia; Casadevall, Margarida

2015-10-28

The capacity for heavy metal bioaccumulation by some fish parasites has been demonstrated, and their contribution to decreasing metal concentrations in tissues of parasitized fish has been hypothesized. The present study evaluated the effect of the cestode Clestobothrium crassiceps on the accumulation of trace elements in 30 European hake, Merluccius merluccius, in Spain (half of them infested by C. crassiceps). Tissue samples from all M. merluccius and specimens of C. crassiceps from the infected hakes were collected and stored until element analysis by inductively coupled plasma mass spectrometry (ICP-MS). Arsenic, mercury, and selenium were generally present in lower levels in the cestode than in all hake tissues. The mean value of the muscular Se:Hg molar ratio in the infested subsample was higher than that in hakes without cestodes. Values indicate that the edible part of infested hakes presents a lower amount of Cd and Pb in relation to noninfested hakes.

Synthesis, spectroscopic characterization, thermal analysis and electrical conductivity studies of Mg(II), Ca(II), Sr(II) and Ba(II) vitamin B2 complexes

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Moussa, Mohamed A. A.; Mohamed, Soha F.

2011-05-01

Riboflavin (RF) complexes of Mg(II), Ca(II), Sr(II) and Ba(II) were successfully synthesized. Structures of metal complexes obtained were confirmed and characterized by elemental analysis, molar conductance, and infrared spectra. DC electrical conductivity measurements indicated that the alkaline earth metal (II) complexes of RF ligand are non-electrolytes. Elemental analysis of chelates suggest that the metal(II) ligand ratio is 1:2 with structure formula as [M(RF) 2( X) 2]· nH 2O. Infrared assignments clearly show that RF ligand coordinated as a bidentate feature through azomethine nitrogen of pyrazine ring and C dbnd O of pyrimidine-2,4-dione. Thermal analyses of Mg(II), Ca(II), Sr(II) and Ba(II) complexes were investigated using (TG/DSC) under atmospheric nitrogen between 30 and 800 °C. The surface morphology of the complexes was studied by SEM. The electrical conductivities of RF and its metal complexes were also measured with DC electrical conductivity in the temperature range from room to 483 K.

Positional changes of the third molar in orthodontically treated patients.

PubMed

Mihai, A M; Lulache, I R; Grigore, R; Sanabil, A S; Boiangiu, S; Ionescu, E

2013-06-15

Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions. This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured. Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student's t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions.

Age estimation using development of third molars in South Indian population: A radiological study

PubMed Central

Priyadharshini, K. Indra; Idiculla, Jose Joy; Sivapathasundaram, B.; Mohanbabu, V.; Augustine, Dominic; Patil, Shankargouda

2015-01-01

Aim: To assess the estimation of chronological age based on the stages of third molar development following the eight stages (A–H) method of Demirjian et al. in Chennai population of South India. Materials and Methods: A sample consisting of 848 individuals (471 males and 377 females) aged between 14 and 30 years was randomly selected for the clinical evaluation and 323 orthopantomograms with clinically missing third molars were taken for radiological evaluation using Demirjian's method from a Chennai population of known chronological age and sex. Statistical analysis was performed using Pearson's Chi-square test and mean values were compared between the study groups using t-test or analysis of variance (ANOVA) followed by Tukey's highly significant difference (HSD). In the present study, P < 0.05 was considered as the level of significance. Results: The results showed that the mean age of having clinically completely erupted maxillary third molars was 22.41 years in male subjects and 23.81 years in female subjects and that of mandibular third molars was 21.49 years in male subjects and 23.34 years in female subjects. Mandibular third molars were clinically missing more often in females than in males. Eruption of mandibular third molars was generally ahead of the emergence of maxillary third molars into the oral cavity. Third molar development between male and female subjects showed statistically significant differences at calcification stage F and stage G in maxillary third molars and stage F in mandibular third molars (P < 0.05). Conclusion: There are differences indicating that maxillary and mandibular third molar eruption reached Demirjian's formation stages earlier in males than in females. It is suggested that in future studies, to increase the accuracy of age determination, indications of sexual maturity and ossification should also be evaluated in addition to third molar mineralization. PMID:25984465

Impacted lower third molars and distal caries in the mandibular second molar. Is prophylactic removal of lower third molars justified?

PubMed

Marques, José; Montserrat-Bosch, Marta; Figueiredo, Rui; Vilchez-Pérez, Miguel-Angel; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2017-06-01

The objective of this study was to evaluate the association between the presence of mandibular third molars and the occurrence of carious lesions in the distal aspect of the mandibular second molar. A retrospective cohort study comprising 327 lower third molars extracted in the Oral Surgery and Implantology Master's Degree program of the School of Dentistry of the University of Barcelona (Barcelona, Spain) was carried out. A descriptive and bivariate analysis was made. The diagnosis of caries in the second molar and the position of the mandibular third molar were evaluated through panoramic radiographies. The sample included 203 patients, 94 males (46.3%) and 109 females (53.7%), with a mean age of 26,8 years and 327 lower third molars. The prevalence of second molar distal caries was 25.4% (95% CI= 20.6% to 30.2%). This pathology was significantly more frequent when the third molar was in a horizontal position (27.7%), when the contact point was at (45,8%) or below (47.0%) the cementoenamel junction (CEJ), and when the distal CEJ of the mandibular second molar and the mesial CEJ of the third molar was 7 to 12 mm apart. Horizontal lower third molars with contact points at or below the CEJ are more likely to produce distal caries in the mandibular second molars. Due to the high prevalence of this pathology (20.6% to 30.2%), a prophylactic removal of lower third molars with the above-mentioned features might be advisable. Key words: Second molar, caries, third molar, prophylactic removal.

An advanced approach for computer modeling and prototyping of the human tooth.

PubMed

Chang, Kuang-Hua; Magdum, Sheetalkumar; Khera, Satish C; Goel, Vijay K

2003-05-01

This paper presents a systematic and practical method for constructing accurate computer and physical models that can be employed for the study of human tooth mechanics. The proposed method starts with a histological section preparation of a human tooth. Through tracing outlines of the tooth on the sections, discrete points are obtained and are employed to construct B-spline curves that represent the exterior contours and dentino-enamel junction (DEJ) of the tooth using a least square curve fitting technique. The surface skinning technique is then employed to quilt the B-spline curves to create a smooth boundary and DEJ of the tooth using B-spline surfaces. These surfaces are respectively imported into SolidWorks via its application protocol interface to create solid models. The solid models are then imported into Pro/MECHANICA Structure for finite element analysis (FEA). The major advantage of the proposed method is that it first generates smooth solid models, instead of finite element models in discretized form. As a result, a more advanced p-FEA can be employed for structural analysis, which usually provides superior results to traditional h-FEA. In addition, the solid model constructed is smooth and can be fabricated with various scales using the solid freeform fabrication technology. This method is especially useful in supporting bioengineering applications, where the shape of the object is usually complicated. A human maxillary second molar is presented to illustrate and demonstrate the proposed method. Note that both the solid and p-FEA models of the molar are presented. However, comparison between p- and h-FEA models is out of the scope of the paper.

Effects of first molar extraction on third molar angulation and eruption space.

PubMed

Bayram, Mehmet; Ozer, Mete; Arici, Selim

2009-02-01

The aim was to investigate the effects of orthodontic treatment with 4 first molar extractions on the angulations and eruption spaces of all third molars and to compare these changes with outcomes of nonextraction samples used as a control group. This study was carried out on standardized panoramic radiographs of 41 subjects (8 male, 33 female) with a mean age of 16.6 years (range 13 to 20 years). Twenty-one of the subjects were orthodontically treated with extraction of the 4 first permanent molars, and 20 had nonextraction treatment. The angulational changes and eruption spaces of third molars were evaluated on the panoramic radiographs taken before treatment and at the end of the observation period. Analysis of the linear variables demonstrated a statistically significant difference between the 2 groups for all third molar eruption spaces (P < .001). The mean differences in the third molar eruption spaces between the pretreatment and posttreatment values for the first molar extraction group were higher than those of the nonextraction cases. Orthodontic treatment accomplished with extractions of the permanent first molars increases the eruption spaces of third molars and decreases their impaction. In addition, it has greater favorable effect on the angulation of the upper third molars than of the lower third molars.

Retrospective study of root canal configurations of maxillary third molars in Central India population using cone beam computed tomography Part- I.

PubMed

Rawtiya, Manjusha; Somasundaram, Pavithra; Wadhwani, Shefali; Munuga, Swapna; Agarwal, Manish; Sethi, Priyank

2016-01-01

The aim of this study was to investigate the root and canal morphology of maxillary third molars in Central India population using cone-beam computed tomography (CBCT) analysis. CBCT images of 116 maxillary third molars were observed, and data regarding the number of roots, the number of canals, and Vertucci's Classification in each root was statistically evaluated. Majority of Maxillary third molars had three roots (55.2%) and three canals (37.9%). Most MB root (43.8%), DB root (87.5%), and palatal root (100%) of maxillary third molars had Vertucci Type I. Mesiobuccal root of three-rooted maxillary third molars had Vertucci Type I (43.8%) and Type IV (40.6%) configuration. Overall prevalence of C-shaped canals in maxillary third molars was 3.4%. There was a high prevalence of three-rooted maxillary molars with three canals.

Toxicity, Spectroscopic Characterization and Electrochemical Behaviour of New Macrocclic Complexes of Lead(II) and Palladium(II) Metals

PubMed Central

Bansal, Anil; Singh, Randhir

2000-01-01

Tetraazamacrocyclie complexes of lead and palladium have been synthesized by the template process using the bis(benzil)ethylenediamine precursor. The tetradentate macrocycle (maL) reacts with PbCl2, PdCl2 and different diamines in a 1:1:1 molar ratio in methanol to give several solid complexes of the types [Pb(maL)(R)Cl2] and [Pd(maL)(R)]Cl2 (where R = 2,6-diaminopyridine or 1,2-phenylenediamine). The macrocycle and its metal complexes have been characterized by elemental analysis, molecular weight determinations, molar conductivity, IR, 1H NMR, 13C NMR, electronic, mass and electrochemical studies. The macrocyclic ligand coordinates through the four azomethine nitrogen atoms which are bridged by benzil moieties. IR spectra suggest that the pyridine nitrogen is not coordinating. The palladium complexes exhibit tetracoordinated square-planar geometry, whereas a hexacoordinated octahedral geometry is suggested for lead complexes. The macrocycle along with its complexes have been screened in vitro against a number of pathogenic fungi and bacteria to assess their growth inhibiting potential. PMID:18475947

QACD: A method for the quantitative assessment of compositional distribution in geologic materials

NASA Astrophysics Data System (ADS)

Loocke, M. P.; Lissenberg, J. C. J.; MacLeod, C. J.

2017-12-01

In order to fully understand the petrogenetic history of a rock, it is critical to obtain a thorough characterization of the chemical and textural relationships of its mineral constituents. Element mapping combines the microanalytical techniques that allow for the analysis of major- and minor elements at high spatial resolutions (e.g., electron microbeam analysis) with 2D mapping of samples in order to provide unprecedented detail regarding the growth histories and compositional distributions of minerals within a sample. We present a method for the acquisition and processing of large area X-ray element maps obtained by energy-dispersive X-ray spectrometer (EDS) to produce a quantitative assessment of compositional distribution (QACD) of mineral populations within geologic materials. By optimizing the conditions at which the EDS X-ray element maps are acquired, we are able to obtain full thin section quantitative element maps for most major elements in relatively short amounts of time. Such maps can be used to not only accurately identify all phases and calculate mineral modes for a sample (e.g., a petrographic thin section), but, critically, enable a complete quantitative assessment of their compositions. The QACD method has been incorporated into a python-based, easy-to-use graphical user interface (GUI) called Quack. The Quack software facilitates the generation of mineral modes, element and molar ratio maps and the quantification of full-sample compositional distributions. The open-source nature of the Quack software provides a versatile platform which can be easily adapted and modified to suit the needs of the user.

A radiographic survey of agenesis of the third molar: A panoramic study.

PubMed

Singh, Nisha; Chaudhari, Shrinivas; Chaudhari, Rohan; Nagare, Sagar; Kulkarni, Abhay; Parkarwar, Pratik

2017-01-01

It is a well-known fact that nature tries to eliminate what is not in use. Because of this, the number of certain teeth which are no longer necessary for function are either getting increasingly impacted or are not developing at all. This is especially the case where third molars are concerned. Furthermore, the presence or absence of the third molar is significant to all branches of dentistry and in particular, forensic dentistry. The objectives of this study is to assess (1) The prevalence of third molar agenesis in population of age group 18-25 years. (2) The genderwise difference of third molar agenesis. (3) The difference between maxilla and mandible. Dental patients, who are advised or referred for orthopantomograph, visited to the Department of Oral Medicine and Radiology were included in the study. The study population comprised 300 patients. The data obtained was tabulated and subjected to statistical analysis. SPSS version 17 software was used for the analysis of the data. The Chi-square test was used for the same. The incidence of agenesis of the third molar is significantly higher for tooth number 18 ( P < 0.001). Overall, it is significantly higher among females compared to the males ( P < 0.001) in our study population. (1) The present study reports 46.7% agenesis of the third molar. (2) The frequency of third molar agenesis was found significantly greater in the females. (3) Third molar agenesis showed a greater predilection in maxilla compared to mandible.

Mechanisms Underlying the Breast Cancer Susceptibility Locus Mcs5a

DTIC Science & Technology

2010-07-01

fixed using formaldehyde . The extracted fixed chromatin is digested with a restriction enzyme and religated in a strongly dilute fashion. In this...procedure the ligation of genetic elements that were glued together by formaldehyde fixation is favored over ligation of random elements. Following... digested and randomly ligated control template containing all restriction fragments of interest in equal molarity. To investigate the Mcs5a1-Mcs5a2

Positional changes of the third molar in orthodontically treated patients

PubMed Central

Mihai, AM; Lulache, IR; Grigore, R; Sanabil, AS; Boiangiu, S; Ionescu, E

2013-01-01

Objective and Rationale. Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions. Method. This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured. Results. Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student’s t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions. PMID:23904878

Impacted lower third molars and distal caries in the mandibular second molar. Is prophylactic removal of lower third molars justified?

PubMed Central

Marques, José; Montserrat-Bosch, Marta; Vilchez-Pérez, Miguel-Angel; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2017-01-01

Background The objective of this study was to evaluate the association between the presence of mandibular third molars and the occurrence of carious lesions in the distal aspect of the mandibular second molar. Material and Methods A retrospective cohort study comprising 327 lower third molars extracted in the Oral Surgery and Implantology Master’s Degree program of the School of Dentistry of the University of Barcelona (Barcelona, Spain) was carried out. A descriptive and bivariate analysis was made. The diagnosis of caries in the second molar and the position of the mandibular third molar were evaluated through panoramic radiographies. Results The sample included 203 patients, 94 males (46.3%) and 109 females (53.7%), with a mean age of 26,8 years and 327 lower third molars. The prevalence of second molar distal caries was 25.4% (95% CI= 20.6% to 30.2%). This pathology was significantly more frequent when the third molar was in a horizontal position (27.7%), when the contact point was at (45,8%) or below (47.0%) the cementoenamel junction (CEJ), and when the distal CEJ of the mandibular second molar and the mesial CEJ of the third molar was 7 to 12 mm apart. Conclusions Horizontal lower third molars with contact points at or below the CEJ are more likely to produce distal caries in the mandibular second molars. Due to the high prevalence of this pathology (20.6% to 30.2%), a prophylactic removal of lower third molars with the above-mentioned features might be advisable. Key words:Second molar, caries, third molar, prophylactic removal. PMID:28638558

Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

NASA Astrophysics Data System (ADS)

Abou-Hussein, Azza A.; Linert, Wolfgang

2014-01-01

Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultraviolet-visible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms.

Asymmetric Outer Bow Length and Cervical Headgear Force System: 3D Analysis Using Finite Element Method.

PubMed

Geramy, Allahyar; Hassanpour, Mehdi; Emadian Razavi, Elham Sadat

2015-03-01

This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths. Four 3D finite element method (FEM) models of a cervical headgear attached to the maxillary first molars were designed in SolidWorks 2010 software and transferred to ANSYS Workbench ver. 11 software. Models contained the first molars, their periodontal ligament (PDL), cancellous and cortical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with differences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer. The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm). As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment. A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use.

Spectroscopic characterization of metal complexes of novel Schiff base. Synthesis, thermal and biological activity studies

NASA Astrophysics Data System (ADS)

Omar, M. M.; Mohamed, Gehad G.; Ibrahim, Amr A.

2009-07-01

Novel Schiff base (HL) ligand is prepared via condensation of 4-aminoantipyrine and 2-aminobenzoic acid. The ligand is characterized based on elemental analysis, mass, IR and 1H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA, DrTGA and DTA). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine N, amino N and deprotonated caroxylic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia Coli, Pseudomonas aeruginosa, Staphylococcus Pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.

Dental morphology and the phylogenetic "place" of Australopithecus sediba.

PubMed

Irish, Joel D; Guatelli-Steinberg, Debbie; Legge, Scott S; de Ruiter, Darryl J; Berger, Lee R

2013-04-12

To characterize further the Australopithecus sediba hypodigm, we describe 22 dental traits in specimens MH1 and MH2. Like other skeletal elements, the teeth present a mosaic of primitive and derived features. The new nonmetric data are then qualitatively and phenetically compared with those in eight other African hominin samples, before cladistic analyses using a gorilla outgroup. There is some distinction, largely driven by contrasting molar traits, from East African australopiths. However, Au. sediba links with Au. africanus to form a South African australopith clade. These species present five apomorphies, including shared expressions of Carabelli's upper first molar (UM1) and protostylid lower first molar (LM1). Five synapomorphies are also evident between them and monophyletic Homo habilis/rudolfensis + H. erectus. Finally, a South African australopith + Homo clade is supported by four shared derived states, including identical LM1 cusp 7 expression.

Transition metal complexes of quinolino[3,2-b]benzodiazepine and quinolino[3,2-b]benzoxazepine: synthesis, characterization, and antimicrobial studies.

PubMed

Basavaraju, B; Naik, Halehatty S Bhojya; Prabhakara, Mustur C

2007-01-01

The synthesis and characterization of title complexes of the ligand Quinolino[3,2-b]benzodiazepine (QBD) and Quinolino[3,2-b]benzoxazepine (QBO) are reported. The complexes have been characterized by elemental analysis, molar conductance, magnetic studies, IR, H1 NMR, and UV-visible studies. They have the stoichiometry [ML2C12], where M=Co(II)/Ni(II), L=QBD/QBO, and [MLC12], where M=Zn(II)/Cd(II), L=QBD/QBO. The antibacterial and antifungal activity of the metal complexes has been investigated. The complexes were found to have higher antimicrobial activity than the parent ligand.

Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

PubMed

Anusavice, Kenneth J; Jadaan, Osama M; Esquivel-Upshaw, Josephine F

2013-11-01

Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm). CARES/Life results support the proposed crown design and load orientation hypotheses. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. Copyright © 2013 Academy of Dental Materials. All rights reserved.

Masticatory loadings and cranial deformation in Macaca fascicularis: a finite element analysis sensitivity study.

PubMed

Fitton, L C; Shi, J F; Fagan, M J; O'Higgins, P

2012-07-01

Biomechanical analyses are commonly conducted to investigate how craniofacial form relates to function, particularly in relation to dietary adaptations. However, in the absence of corresponding muscle activation patterns, incomplete muscle data recorded experimentally for different individuals during different feeding tasks are frequently substituted. This study uses finite element analysis (FEA) to examine the sensitivity of the mechanical response of a Macaca fascicularis cranium to varying muscle activation patterns predicted via multibody dynamic analysis. Relative to the effects of varying bite location, the consequences of simulated variations in muscle activation patterns and of the inclusion/exclusion of whole muscle groups were investigated. The resulting cranial deformations were compared using two approaches; strain maps and geometric morphometric analyses. The results indicate that, with bite force magnitude controlled, the variations among the mechanical responses of the cranium to bite location far outweigh those observed as a consequence of varying muscle activations. However, zygomatic deformation was an exception, with the activation levels of superficial masseter being most influential in this regard. The anterior portion of temporalis deforms the cranial vault, but the remaining muscles have less profound effects. This study for the first time systematically quantifies the sensitivity of an FEA model of a primate skull to widely varying masticatory muscle activations and finds that, with the exception of the zygomatic arch, reasonable variants of muscle loading for a second molar bite have considerably less effect on cranial deformation and the resulting strain map than does varying molar bite point. The implication is that FEA models of biting crania will generally produce acceptable estimates of deformation under load as long as muscle activations and forces are reasonably approximated. In any one FEA study, the biological significance of the error in applied muscle forces is best judged against the magnitude of the effect that is being investigated. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.

Masticatory loadings and cranial deformation in Macaca fascicularis: a finite element analysis sensitivity study

PubMed Central

Fitton, L C; Shi, J F; Fagan, M J; O’Higgins, P

2012-01-01

Biomechanical analyses are commonly conducted to investigate how craniofacial form relates to function, particularly in relation to dietary adaptations. However, in the absence of corresponding muscle activation patterns, incomplete muscle data recorded experimentally for different individuals during different feeding tasks are frequently substituted. This study uses finite element analysis (FEA) to examine the sensitivity of the mechanical response of a Macaca fascicularis cranium to varying muscle activation patterns predicted via multibody dynamic analysis. Relative to the effects of varying bite location, the consequences of simulated variations in muscle activation patterns and of the inclusion/exclusion of whole muscle groups were investigated. The resulting cranial deformations were compared using two approaches; strain maps and geometric morphometric analyses. The results indicate that, with bite force magnitude controlled, the variations among the mechanical responses of the cranium to bite location far outweigh those observed as a consequence of varying muscle activations. However, zygomatic deformation was an exception, with the activation levels of superficial masseter being most influential in this regard. The anterior portion of temporalis deforms the cranial vault, but the remaining muscles have less profound effects. This study for the first time systematically quantifies the sensitivity of an FEA model of a primate skull to widely varying masticatory muscle activations and finds that, with the exception of the zygomatic arch, reasonable variants of muscle loading for a second molar bite have considerably less effect on cranial deformation and the resulting strain map than does varying molar bite point. The implication is that FEA models of biting crania will generally produce acceptable estimates of deformation under load as long as muscle activations and forces are reasonably approximated. In any one FEA study, the biological significance of the error in applied muscle forces is best judged against the magnitude of the effect that is being investigated. PMID:22690885

Time-dependent fracture probability of bilayer, lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation

PubMed Central

Anusavice, Kenneth J.; Jadaan, Osama M.; Esquivel–Upshaw, Josephine

2013-01-01

Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. Objective The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6 mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Materials and methods Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Results Predicted fracture probabilities (Pf) for centrally-loaded 1,6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8 mm/0.8 mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4 mm/1.2 mm). Conclusion CARES/Life results support the proposed crown design and load orientation hypotheses. Significance The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. PMID:24060349

Functional Evolution of the Feeding System in Rodents

PubMed Central

Cox, Philip G.; Rayfield, Emily J.; Fagan, Michael J.; Herrel, Anthony; Pataky, Todd C.; Jeffery, Nathan

2012-01-01

The masticatory musculature of rodents has evolved to enable both gnawing at the incisors and chewing at the molars. In particular, the masseter muscle is highly specialised, having extended anteriorly to originate from the rostrum. All living rodents have achieved this masseteric expansion in one of three ways, known as the sciuromorph, hystricomorph and myomorph conditions. Here, we used finite element analysis (FEA) to investigate the biomechanical implications of these three morphologies, in a squirrel, guinea pig and rat. In particular, we wished to determine whether each of the three morphologies is better adapted for either gnawing or chewing. Results show that squirrels are more efficient at muscle-bite force transmission during incisor gnawing than guinea pigs, and that guinea pigs are more efficient at molar chewing than squirrels. This matches the known diet of nuts and seeds that squirrels gnaw, and of grasses that guinea pigs grind down with their molars. Surprisingly, results also indicate that rats are more efficient as well as more versatile feeders than both the squirrel and guinea pig. There seems to be no compromise in biting efficiency to accommodate the wider range of foodstuffs and the more general feeding behaviour adopted by rats. Our results show that the morphology of the skull and masticatory muscles have allowed squirrels to specialise as gnawers and guinea pigs as chewers, but that rats are high-performance generalists, which helps explain their overwhelming success as a group. PMID:22558427

Production of Biodiesel by Esterification of Free Fatty Acid over Solid Catalyst from Biomass Waste

NASA Astrophysics Data System (ADS)

Mukti, N. I. F.; Sutrisno, B.; Hidayat, A.

2018-05-01

Recently, low cost feedstocks have been utilized to replace vegetable oils in order to improve the economic feasibility of biodiesel. The esterification of free fatty acid (FFA) on Palm Fatty Acid Distillate (PFAD) with methanol using solid catalyst generated from bagasse fly ash is a promising method to convert FFA into biodiesel. In this research, the esterification of FFA on PFAD using the sulfonated bagasse fly ash catalyst was studied. The performances of the catalysts were evaluated in terms of the reaction temperatures, the molar ratios of methanol to PFAD, and the catalyst loading. The effects of the mass ratio of catalyst to oil (1-10%), the molar ratio of methanol to oil (6:1-12:1), and the reaction temperature (40-60°C) were studied for the conversion of PFAD to optimize the reaction conditions. The results showed that the optimum conditions were methanol to PFAD molar ratio of 12:1, the amount of catalyst of 10%wt. of PFAD, and reaction temperature of 6°C. The reusability of the solid acid carbon catalysts was also studied in this work. The catalytic activity decreased up to 38% after third cycle. The significant decline in catalyst esterification activity was due to acid site leaching. The physico-characteristics and acid site densities were analyzed by Nitrogen gas adsorption, surface functional groups by Fourier transform infrared spectroscopy (FT-IR), elemental analysis using X-ray fluorescent (XRF), and acid-base back titration methods for determination of acid density.

Synthesis, characterization, and antipathogenic studies of some transition metal complexes with N,O-chelating Schiff's base ligand incorporating azo and sulfonamide Moieties

NASA Astrophysics Data System (ADS)

Alaghaz, Abdel-Nasser M. A.; Bayoumi, Hoda A.; Ammar, Yousry A.; Aldhlmani, Sharah A.

2013-03-01

Chromium(III), Manganese(II), Cobalt(II), nickel(II), copper(II) and cadmium(II) complexes of 4-[4-hydroxy-3-(phenyliminomethyl)-phenylazo]benzenesulfonamide, were prepared and characterized on the basis of elemental analyses, spectral, magnetic, molar conductance and thermal analysis. Square planar, tetrahedral and octahedral geometries have been assigned to the prepared complexes. Dimeric complexes are obtained with 2:2 molar ratio except chromium(III) complex is monomeric which is obtained with 1:1 molar ratios. The IR spectra of the prepared complexes were suggested that the Schiff base ligand(HL) behaves as a bi-dentate ligand through the azomethine nitrogen atom and phenolic oxygen atom. The crystal field splitting, Racah repulsion and nepheloauxetic parameters and determined from the electronic spectra of the complexes. Thermal studies suggest a mechanism for degradation of HL and its metal complexes as function of temperature supporting the chelation modes. Also, the activation thermodynamic parameters, such as ΔE*, ΔH*, ΔS* and ΔG* for the different thermal decomposition steps of HL and its metal complexes were calculated. The pathogenic activities of the synthesized compounds were tested in vitro against the sensitive organisms Staphylococcus aureus (RCMB010027), Staphylococcus epidermidis (RCMB010024) as Gram positive bacteria, Klebsiella pneumonia (RCMB 010093), Shigella flexneri (RCMB 0100542), as Gram negative bacteria and Aspergillus fumigates (RCMB 02564), Aspergillus clavatus (RCMB 02593) and Candida albicans (RCMB05035) as fungus strain, and the results are discussed.

[Clinical analysis of caries status of the mandibular second molar].

PubMed

You, Chun-an; Zheng, Ping; Hu, Ning; Su, Qin

2014-04-01

To collect the cases which have caries on the mandibular second molar and analyze the caries status and correlative factors. Patients treated in the Department of Endodontics in West China Hospital of Stomatology were randomly collected. The baseline information, primary sites and severity of dental caries on the mandibular second molar, and eruption pattern of the mandibular third molar were recorded. The data was analyzed with SPSS13.0 software package. Four hundred eighty-one patients including 227 males and 254 females were collected. Caries on the mandibular second molar starting from the occlusal, distal proximal and buccal surfaces accounted for 33.8%, 33.2% and 24.4%, respectively. Caries involving dental pulp (49.7%) were significantly more than deep and shallow to moderate caries (31.7% and 18.6%). Gender was not correlated with the site and severity of caries. However, impacted mandibular third molars and age were significantly related to both caries site and severity. Occlusal and distal proximal surfaces are the most predisposed sites to have caries on mandibular second molar. Impacted mandibular third molar and age are significantly related to caries of mandibular second molar.

Retrospective study of root canal configurations of maxillary third molars in Central India population using cone beam computed tomography Part- I

PubMed Central

Rawtiya, Manjusha; Somasundaram, Pavithra; Wadhwani, Shefali; Munuga, Swapna; Agarwal, Manish; Sethi, Priyank

2016-01-01

Objective: The aim of this study was to investigate the root and canal morphology of maxillary third molars in Central India population using cone-beam computed tomography (CBCT) analysis. Materials and Methods: CBCT images of 116 maxillary third molars were observed, and data regarding the number of roots, the number of canals, and Vertucci's Classification in each root was statistically evaluated. Results: Majority of Maxillary third molars had three roots (55.2%) and three canals (37.9%). Most MB root (43.8%), DB root (87.5%), and palatal root (100%) of maxillary third molars had Vertucci Type I. Mesiobuccal root of three-rooted maxillary third molars had Vertucci Type I (43.8%) and Type IV (40.6%) configuration. Overall prevalence of C-shaped canals in maxillary third molars was 3.4%. Conclusion: There was a high prevalence of three-rooted maxillary molars with three canals. PMID:27011747

Retrospective Study of Root Canal Configurations of Mandibular Third Molars Using CBCT- Part-II.

PubMed

Somasundaram, Pavithra; Rawtiya, Manjusha; Wadhwani, Shefali; Uthappa, Roshan; Shivagange, Vinay; Khan, Sheeba

2017-06-01

Abnormal root canal morphologies of third molars can be diagnostically and technically challenging during root canal treatment. The aim of this retrospective study was to investigate the root and canal morphology of mandibular third molars in Central India population by using Cone Beam Computed Tomography (CBCT) analysis. CBCT images of 171 mandibular third molars were observed and data regarding number of roots, number of canals, Vertucci's classification in each root, prevalence of C shaped canal, gender and topographical relation of morphology in mandibular third molar was statistically evaluated. Majority of mandibular third molars had two roots (84.2%) and three canals (64.3%). Most mesial root had Vertucci Type II (55.6%) and Vertucci Type IV (22.2%), distal root had Type I canals (87.5%). Over all prevalence of C shaped canals in mandibular third molars was 9.4%. There was a high prevalence of two rooted mandibular third molars with three canals.

Retrospective Study of Root Canal Configurations of Mandibular Third Molars Using CBCT- Part-II

PubMed Central

Somasundaram, Pavithra; Wadhwani, Shefali; Uthappa, Roshan; Shivagange, Vinay; Khan, Sheeba

2017-01-01

Introduction Abnormal root canal morphologies of third molars can be diagnostically and technically challenging during root canal treatment. Aim The aim of this retrospective study was to investigate the root and canal morphology of mandibular third molars in Central India population by using Cone Beam Computed Tomography (CBCT) analysis. Materials and Methods CBCT images of 171 mandibular third molars were observed and data regarding number of roots, number of canals, Vertucci’s classification in each root, prevalence of C shaped canal, gender and topographical relation of morphology in mandibular third molar was statistically evaluated. Results Majority of mandibular third molars had two roots (84.2%) and three canals (64.3%). Most mesial root had Vertucci Type II (55.6%) and Vertucci Type IV (22.2%), distal root had Type I canals (87.5%). Over all prevalence of C shaped canals in mandibular third molars was 9.4%. Conclusion There was a high prevalence of two rooted mandibular third molars with three canals. PMID:28764294

Clinical significance of computed tomography assessment for third molar surgery

PubMed Central

Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

2014-01-01

Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery. Third molar surgery is warranted when there is inadequate space for eruption, malpositioning, or risk for cyst or odontogenic tumor formation. Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues. Due to developments in medical engineering technology, computed tomography (CT) now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery. Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation, whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve. Multiple factors, including demographic, anatomic, and treatment-related factors, influence the incidence of nerve injury during or following removal of the third molar. CT assessment of the third molar prior to surgery can identify some of these risk factors, such as the absence of cortication between the mandibular third molar and the inferior alveolar canal, prior to surgery to reduce the risk for nerve damage. This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery. PMID:25071882

The Role of Microbial Iron Reduction in the Formation of Proterozoic Molar Tooth Structures

NASA Astrophysics Data System (ADS)

Hodgskiss, M. S. W.; Kunzmann, M.; Halverson, G. P.; Poirier, A.

2016-12-01

Molar tooth structures are poorly understood early diagenetic, microspar-filled voids in clay-rich carbonate sediments. They are a common structure in sedimentary successions dating from 2600-720 Ma, but do not occur in rocks older or younger. Despite being volumetrically significant in carbonate rocks of this age, their formation and disappearance are poorly understood. Here, we present iron isotope data, supported by carbon and oxygen isotopes, major and minor element concentrations, and total organic carbon and pyrite contents for samples from ten regions spanning 1870-635 Ma. The iron isotopic composition of molar tooth structures is almost always lighter (modal depletion of 2‰) than the carbonate or siliciclastic components in the host sediment, whereas carbon isotopes are indistinguishable. We interpret the isotopically light iron in molar tooth structures to have been produced by microbial iron reduction utilising Fe-oxyhydroxides and smectites. The microbial conversion of smectite to illite results in a volume reduction of clay minerals ( 30%), while locally increasing pore water alkalinity. Therefore, this biogeochemical process is a viable mechanism to produce voids and subsequently precipitate carbonate minerals. The disappearance of molar tooth structures is likely linked to a combination of a decrease in smectite abundance, a decline in the marine DIC reservoir, and increase in the concentration of O2 in shallow seawater in the mid-Neoproterozoic.

A geometric morphometric analysis of hominin upper second and third molars, with particular emphasis on European Pleistocene populations.

PubMed

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2012-09-01

The study of dental morphology by means of geometric morphometric methods allows for a detailed and quantitative comparison of hominin species that is useful for taxonomic assignment and phylogenetic reconstruction. Upper second and third molars have been studied in a comprehensive sample of Plio- and Pleistocene hominins from African, Asian and European sites in order to complete our analysis of the upper postcanine dentition. Intraspecific variation in these two molars is high, but some interspecific trends can be identified. Both molars exhibit a strong reduction of the distal cusps in recent hominin species, namely European Homo heidelbergensis, Homo neanderthalensis and Homo sapiens, but this reduction shows specific patterns and proportions in the three groups. Second molars tend to show four well developed cusps in earlier hominin species and their morphology is only marginally affected by allometric effects. Third molars can be incipiently reduced in earlier species and they evince a significant allometric component, identified both inter- and intraspecifically. European Middle Pleistocene fossils from Sima de los Huesos (SH) show a very strong reduction of these two molars, even more marked than the reduction observed in Neanderthals and in modern human populations. The highly derived shape of SH molars points to an early acquisition of typical Neanderthal dental traits by pre-Neanderthal populations and to a deviation of this population from mean morphologies of other European Middle Pleistocene groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

Prevalence of Distal Caries in Mandibular Second Molar Due to Impacted Third Molar

PubMed Central

Alshahrani, Fatima Saeed; Alabsi, Wejdan Saad; Alqahtani, Zainab Ali; Hameed, Mohammad Shahul; Mustafa, Abdel Bagi; Alam, Tanveer

2017-01-01

Introduction A tooth is said to be impacted if it does not reach the occlusal plane even after two-thirds root formation. The aetiology of impacted teeth is varied and multi-factorial. Significant problems associated with impacted teeth include trismus, infection, cervical caries of second molars. Aim This study was aimed to assess the prevalence of distal caries in second molar teeth due to impacted third molars and to compare with similar studies conducted elsewhere. Materials and Methods Study included assessment of patients reporting between 2009 to 2014 for dental care at College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia. This is a retrospective cross-sectional study which included a total of 6000 Orthopantomograms (OPGs). The data collected was decoded and entered into excel spread sheet. Descriptive analysis of the data was done and results were displayed as frequency table and graphs. Results A total of 979 patients had impacted third molars (16.31%). A total of 39% patient’s with impacted third molars had distal cervical caries in second molar. Mesioangular impaction was the most prominent type. This was closely followed by horizontal impaction causing distal caries in second molars. Age group between 21-28 years and male gender had the higher prevalence of distal caries in second molar teeth due to impacted third molars. Conclusion A total of 39% of the patients with impacted mandibular third molars had distal cervical caries in second molars. Mesioangular type, male gender, age group 21-28 years were the prominent factors associated with distal caries in second molar teeth due to impacted third molars. PMID:28511504

Production and characterization of a bioflocculant produced by Aspergillus flavus.

PubMed

Aljuboori, Ahmad H Rajab; Idris, Azni; Abdullah, Norhafizah; Mohamad, Rosfarizan

2013-01-01

The production and characterization of a bioflocculant, IH-7, by Aspergillus flavus was investigated. About 0.4 g of purified bioflocculant with an average molecular weight of 2.574 × 10(4)Da could be obtained from 1L of fermentation medium. The bioflocculant mainly consisted of protein (28.5%) and sugar (69.7%), including 40% of neutral sugar, 2.48% of uronic acid and 1.8% amino sugar. The neutral sugar components are sucrose, lactose, glucose, xylose, galactose, mannose and fructose at a molar ratio of 2.4:4.4:4.1:5.8:9.9:0.8:3.1. Fourier-transform infrared spectroscopy analysis revealed that purified IH-7 contained hydroxyl, amide, carboxyl and methoxyl groups. The elemental analysis of purified IH-7 showed that the weight fractions of the elements C, H, O, N and S were 29.9%, 4.8%, 34.7%, 3.3%, and 2.0%, respectively. IH-7 had good flocculating rate in kaolin suspension without cation addition and stable over wide range of pH and temperature. Copyright © 2012. Published by Elsevier Ltd.

Statistical analysis of major ion and trace element geochemistry of water, 1986-2006, at seven wells transecting the freshwater/saline-water interface of the Edwards Aquifer, San Antonio, Texas

USGS Publications Warehouse

Mahler, Barbara J.

2008-01-01

The statistical analyses taken together indicate that the geochemistry at the freshwater-zone wells is more variable than that at the transition-zone wells. The geochemical variability at the freshwater-zone wells might result from dilution of ground water by meteoric water. This is indicated by relatively constant major ion molar ratios; a preponderance of positive correlations between SC, major ions, and trace elements; and a principal components analysis in which the major ions are strongly loaded on the first principal component. Much of the variability at three of the four transition-zone wells might result from the use of different laboratory analytical methods or reporting procedures during the period of sampling. This is reflected by a lack of correlation between SC and major ion concentrations at the transition-zone wells and by a principal components analysis in which the variability is fairly evenly distributed across several principal components. The statistical analyses further indicate that, although the transition-zone wells are less well connected to surficial hydrologic conditions than the freshwater-zone wells, there is some connection but the response time is longer. 

Parafunctional loading and occlusal device on stress distribution around implants: A 3D finite element analysis.

PubMed

Borges Radaelli, Manuel Tomás; Idogava, Henrique Takashi; Spazzin, Aloisio Oro; Noritomi, Pedro Yoshito; Boscato, Noéli

2018-04-30

An occlusal device is frequently recommended for patients with bruxism to protect implant-supported restorations and prevent marginal bone loss. Scientific evidence to support this treatment is lacking. The purpose of this 3-dimensional (3D) finite element study was to evaluate the influence of an acrylic resin occlusal device, implant length, and insertion depth on stress distribution with functional and parafunctional loadings. Computer-aided design software was used to construct 8 models. The models were composed of a mandibular bone section including the second premolar and first and second molars. Insertion depths (bone level and 2 mm subcrestal) were simulated at the first molar. Three natural antagonist maxillary teeth and the placement or not of an occlusal device were simulated. Functional (200-N axial and 10-N oblique) and parafunctional (1000-N axial and 25-N oblique) forces were applied. Finite element analysis (FEA) was used to determine the maximum principal stress for the cortical and trabecular bone and von Mises for implant and prosthetic abutment. Stress concentration was observed at the abutment-implant and the implant-bone interfaces. Occlusal device placement changed the pattern of stress distribution and reduced stress levels from parafunctional loading in all structures, except in the trabecular bone. Implants with subcrestal insertion depths had reduced stress at the implant-abutment interface and cortical bone around the implant abutment, while the stress increased in the bone in contact with the implant. Parafunctional loading increased the stress levels in all structures when compared with functional loading. An occlusal device resulted in the lowest stress levels at the abutment and implant and the most favorable stress distribution between the cortical and trabecular bone. Under parafunctional loading, an occlusal device was more effective in reducing stress distribution for longer implants inserted at bone level. Subcrestally, implant insertion yielded the most favorable biomechanical conditions at the abutment-implant interface and at the coronal surface of the cortical bone, mainly when there was no occlusal device. Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Demirjian's method in the estimation of age: A study on human third molars.

PubMed

Lewis, Amitha J; Boaz, Karen; Nagesh, K R; Srikant, N; Gupta, Neha; Nandita, K P; Manaktala, Nidhi

2015-01-01

The primary aim of the following study is to estimate the chronological age based on the stages of third molar development following the eight stages (A to H) method of Demirjian et al. (along with two modifications-Orhan) and secondary aim is to compare third molar development with sex and age. The sample consisted of 115 orthopantomograms from South Indian subjects with known chronological age and gender. Multiple regression analysis was performed with chronological age as the dependable variable and third molar root development as independent variable. All the statistical analysis was performed using the SPSS 11.0 package (IBM ® Corporation). Statistically no significant differences were found in third molar development between males and females. Depending on the available number of wisdom teeth in an individual, R (2) varied for males from 0.21 to 0.48 and for females from 0.16 to 0.38. New equations were derived for estimating the chronological age. The chronological age of a South Indian individual between 14 and 22 years may be estimated based on the regression formulae. However, additional studies with a larger study population must be conducted to meet the need for population-based information on third molar development.

A prospective study on transplantation of third molars with complete root formation.

PubMed

Mejàre, Bertil; Wannfors, Karin; Jansson, Leif

2004-02-01

The study objective was to evaluate the prognosis for autotransplantation of third molar teeth with fully developed roots followed by endodontic treatment on the basis of a time-table analysis. A total of 50 third molars with completely developed roots were autotransplanted to replace a lost first or second molar in the same number of admitted patients. Root canal treatment was started 3 to 4 weeks later. Clinical and radiographic checkup of the transplanted and root-filled third molars was done annually according to a predesigned record form. Descriptive statistics including a life table and statistical analysis were performed. The cumulative survival rate during 4 years' follow-up was 81.4%. In all, 7 transplants were lost during the follow-up time, 4 of them due to marginal periodontal pathosis and the other 3 due to root resorption. None of the root resorptions was observed before the second postoperative year. The radiographic periapical status was considered normal in 96% of the transplants at the latest follow-up visit. Autotransplantation of mature third molar teeth is a reasonable treatment alternative to conventional prosthetic rehabilitation or implant treatment in cases of partial edentualism from both a therapeutic and an economic point of view.

A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

PubMed

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2015-05-01

Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

The unfolding effects on the protein hydration shell and partial molar volume: a computational study.

PubMed

Del Galdo, Sara; Amadei, Andrea

2016-10-12

In this paper we apply the computational analysis recently proposed by our group to characterize the solvation properties of a native protein in aqueous solution, and to four model aqueous solutions of globular proteins in their unfolded states thus characterizing the protein unfolded state hydration shell and quantitatively evaluating the protein unfolded state partial molar volumes. Moreover, by using both the native and unfolded protein partial molar volumes, we obtain the corresponding variations (unfolding partial molar volumes) to be compared with the available experimental estimates. We also reconstruct the temperature and pressure dependence of the unfolding partial molar volume of Myoglobin dissecting the structural and hydration effects involved in the process.

Three-dimensional computed topography analysis of a patient with an unusual anatomy of the maxillary second and third molars.

PubMed

Zhao, Jin; Li, Yan; Yang, Zhi-Wei; Wang, Wei; Meng, Yan

2011-10-01

We present a case of a patient with rare anatomy of a maxillary second molar with three mesiobuccal root canals and a maxillary third molar with four separate roots, identified using multi-slice computed topography (CT) and three-dimensional reconstruction techniques. The described case enriched/might enrich our knowledge about possible anatomical aberrations of maxillary molars. In addition, we demonstrate the role of multi-slice CT as an objective tool for confirmatory diagnosis and successful endodontic management.

Implant-retained mandibular bar-supported overlay dentures: a finite element stress analysis of four different bar heights.

PubMed

Rismanchian, Mansoor; Dakhilalian, Mansour; Bajoghli, Farshad; Ghasemi, Ehsan; Sadr-Eshkevari, Pooyan

2012-04-01

Proper stress distribution on dental implants is necessary in bar-retained implant overlay dentures. We aimed to comparatively assess this stress distribution according to different bar heights using finite element models. A three-dimensional (3D) computer model of mandible with 2 implants (ITI, 4.1 mm diameter and 12 mm length) in canine areas and an overlying implant-supported bar-retained overlay denture were simulated with 0-, 1-, 2-, and 3-mm bar heights using ABAQUS software. A vertical force was applied to the left first molar and gradually increased from 0 to 50 N. The resultant stress distribution was evaluated. Bars of 1 and 2 mm in height transferred the least stress to the implants (3.882 and 3.896 MPa, respectively). The 0-mm height of the bar connection transferred the highest stress value (4.277 MPa). The amount of stress transferred by 3-mm heights of the bar connection was greater than that of 1- and 2-mm bar connections and smaller than that of 0-mm bar connection (4.165 kgN). This 3D finite element analysis study suggested that the use of Dolder bar attachment with 1- and 2-mm heights could be associated with appropriate stress distribution for implant-retained overlay dentures.

A Critical Review of High Entropy Alloys and Related Concepts (Postprint)

DTIC Science & Technology

2016-10-21

448e511 451The purpose of this paper is to critically assess the major ideas and proposed characteristics of high entropy and multi-principal element...re-introduced once again to put the modern HEA and MPEA concepts into his- torical perspective [17]. A second paper of historical note applied the...MPEA concept to metallic glasses [19]. This paper used equi- molar substitution of chemically similar elements in a known metallic glass alloy. This is

Archaeological Investigations at the Grant River Public Use Area. Volume 1. Narrative.

DTIC Science & Technology

1984-12-01

St. Paul, Minnesota 55101-1479 Ms. Patricia Emerson Impact Services, Inc. P.O. Box 3224 Mankato, Minnesota 56001 Mr. Alan Van Dyke Berg- Zimmer and...biface was recovered. It is basally thinned with very weak shoulders . No grinding occurs on either the lateral margins or on the concave base... anatomical elements (see Appendix C). A minimum number of individuals is 16, based on the most frequently occurring element, the right mandibular first molar

Molar axis estimation from computed tomography images.

PubMed

Dongxia Zhang; Yangzhou Gan; Zeyang Xia; Xinwen Zhou; Shoubin Liu; Jing Xiong; Guanglin Li

2016-08-01

Estimation of tooth axis is needed for some clinical dental treatment. Existing methods require to segment the tooth volume from Computed Tomography (CT) images, and then estimate the axis from the tooth volume. However, they may fail during estimating molar axis due to that the tooth segmentation from CT images is challenging and current segmentation methods may get poor segmentation results especially for these molars with angle which will result in the failure of axis estimation. To resolve this problem, this paper proposes a new method for molar axis estimation from CT images. The key innovation point is that: instead of estimating the 3D axis of each molar from the segmented volume, the method estimates the 3D axis from two projection images. The method includes three steps. (1) The 3D images of each molar are projected to two 2D image planes. (2) The molar contour are segmented and the contour's 2D axis are extracted in each 2D projection image. Principal Component Analysis (PCA) and a modified symmetry axis detection algorithm are employed to extract the 2D axis from the segmented molar contour. (3) A 3D molar axis is obtained by combining the two 2D axes. Experimental results verified that the proposed method was effective to estimate the axis of molar from CT images.

Prevalence of third molars and pathological changes related to them in dental medicine.

PubMed

Mikić, Ivana Medvedec; Zore, Irina Filipović; Crcić, Vlatka Fuchs; Matijević, Jurica; Plancak, Dario; Katunarić, Marina; Buković, Dino

2013-09-01

The purpose of this study was to determine the prevalence of third molars in terms of respondents' age. Furthermore it was desired to determine the extent of the manifestation of pathological changes, such as caries, apical lesions, and alveolar bone resorption. This study was based on 500 OPGs of patients from the Faculty of Dentistry, University of Zagreb. Patients were divided into seven age groups. The total number of molars, the number of cavities on remaining molars, the quality of endodontic treatment and the evaluation of their performance and presence of periapical lesions was analyzed. As apart of the periodontal status, the number of inadequate fillings, the number of damaged furcations and bone resorption was analyzed. The statistical analysis was performed by means of STATISTICA 7 statistical package (StatSoft, Tulsa, USA). The correlation between the total number of molars and the age of patients was analyzed by means of Spearman's correlation to the level of significance of 0.05. The number of first, second and third molars significantly decreased in higher age groups. The prevalence of caries in third molars as compared to first and second molars was generally lower, third molars were endodontic treated at least. Assessment of involved furcations showed that the lowest percentage of 8% was found in third molars. The majority of all remaining molars had bone resorption of 1-3 mm.

Analysis of C-shaped root canal configuration in maxillary molars in a Korean population using cone-beam computed tomography

PubMed Central

Jo, Hyoung-Hoon; Min, Jeong-Bum

2016-01-01

Objectives The purpose of this study was to investigate the incidence of root fusion and C-shaped root canals in maxillary molars, and to classify the types of C-shaped canal by analyzing cone-beam computed tomography (CBCT) in a Korean population. Materials and Methods Digitized CBCT images from 911 subjects were obtained in Chosun University Dental Hospital between February 2010 and July 2012 for orthodontic treatment. Among them, a total of selected 3,553 data of maxillary molars were analyzed retrospectively. Tomography sections in the axial, coronal, and sagittal planes were displayed by PiViewstar and Rapidia MPR software (Infinitt Co.). The incidence and types of root fusion and C-shaped root canals were evaluated and the incidence between the first and the second molar was compared using Chi-square test. Results Root fusion was present in 3.2% of the first molars and 19.5% of the second molars, and fusion of mesiobuccal and palatal root was dominant. C-shaped root canals were present in 0.8% of the first molars and 2.7% of the second molars. The frequency of root fusion and C-shaped canal was significantly higher in the second molar than the first molar (p < 0.001). Conclusions In a Korean population, maxillary molars showed total 11.3% of root fusion and 1.8% of C-shaped root canals. Furthermore, root fusion and C-shaped root canals were seen more frequently in the maxillary second molars. PMID:26877991

[Establish Assessment Model of 18 Years of Age in Chinese Han Population by Mandibular Third Molar].

PubMed

Fan, Fei; Dai, Xin-hua; Wang, Liang; Li, Yuan; Zhang, Kui; Deng, Zhen-hua

2016-02-01

To explore the value of estimating chronologic age based on the grades of mandibular third molar development. To evaluate whether mandibular third molar could be used as an indicator for estimating the age under or over 18 years. The mineralization status of mandibular third molar of 1 845 individuals aged 10 - 30 was graded and marked based on Demirjian's classification of grades reformed by Orhan. Gender difference was examined by t-test. A cubic regression model was established to analyze the correlation between third molar and chronologic age. Each grade of age cumulative distribution diagram and ROC curve was respectively performed to evaluate the relationship between third molar and the age of 18. Using Bayes discriminant analysis, an equation was established for estimating the age of 18. The inner-rater reliability was 0.903. Statistical analysis showed a moderate correlation between age and grade. Significant differences of both genders were found only in grade D and H (P < 0.05). Males at the grades from 1 to D and females at the grades from 1 to C were under 18 years old, and both males and females at grade H were over 18 years old. The area under the ROC curve was 0.797 (P < 0.05). Third molar development shows a high correlation with age, and combined with other indicators, it can be used to estimate the age of 18.

External root resorption of the second molar associated with mesially and horizontally impacted mandibular third molar: evidence from cone beam computed tomography.

PubMed

Wang, Dongmiao; He, Xiaotong; Wang, Yanling; Li, Zhongwu; Zhu, Yumin; Sun, Chao; Ye, Jinhai; Jiang, Hongbing; Cheng, Jie

2017-05-01

The aim of the present study was to assess the incidence and risk factors of ERR in second molars with mesially and horizontally impacted mandibular third molars using cone beam computed tomography (CBCT) images from patients in a Chinese tertiary referral hospital. A total number of 216 patients with 362 mesially and horizontally impacted mandibular third molars who were treated at our institution from 2014 to 2015 was retrospectively included. The ERR in second molars was identified on CBCT multiplanar images. The associations between incidence of ERR and multiple clinical parameters were statistically analyzed by Chi-square test. Moreover, the risk factors for ERR in second molars were further assessed by multivariate regression analysis. The overall incidence of ERR in second molars was 20.17 % (73/362) as detected on CBCT images. The presence of ERR significantly associated with patients age and impaction depth of mandibular third molars. However, no significant relationship was found between ERR severity and impaction depth or ERR location. Multivariate regression analyses further revealed age over 35 years and impaction depth as important risk factors affecting the ERR incidence caused by mesial and horizontal impaction of mandibular third molar. ERR in second molar resulted from mesially and horizontally impacted mandibular third molar is not very rare and can be reliably identified via CBCT scan. Given the possibility of ERR associated with third molar impaction, the prophylactic removal of these impacted teeth could be considered especially for those patients with over 35 years and mesially and horizontally impacted teeth.

Absorption of nickel, chromium, and iron by the root surface of primary molars covered with stainless steel crowns.

PubMed

Keinan, David; Mass, Eliyahu; Zilberman, Uri

2010-01-01

Objective. The purpose of this study was to analyze the absorption of metal ions released from stainless steel crowns by root surface of primary molars. Study Design. Laboratory research: The study included 34 primary molars, exfoliated or extracted during routine dental treatment. 17 molars were covered with stainless-steel crowns for more than two years and compared to 17 intact primary molars. Chemical content of the mesial or distal root surface, 1 mm apically to the crown or the cemento-enamel junction (CEJ), was analyzed. An energy dispersive X-ray spectrometer (EDS) was used for chemical analysis. Results. Higher amounts of nickel, chromium, and iron (5-6 times) were found in the cementum of molars covered with stainless-steel crowns compared to intact molars. The differences between groups were highly significant (P < .001). Significance. Stainless-steel crowns release nickel, chromium, and iron in oral environment, and the ions are absorbed by the primary molars roots. The additional burden of allergenic metals should be reduced if possible.

Morphometric variation of extant platyrrhine molars: taxonomic implications for fossil platyrrhines

PubMed Central

Nova Delgado, Mónica; Galbany, Jordi

2016-01-01

The phylogenetic position of many fossil platyrrhines with respect to extant ones is not yet clear. Two main hypotheses have been proposed: the layered or successive radiations hypothesis suggests that Patagonian fossils are Middle Miocene stem platyrrhines lacking modern descendants, whereas the long lineage hypothesis argues for an evolutionary continuity of all fossil platyrrhines with the extant ones. Our geometric morphometric analysis of a 15 landmark-based configuration of platyrrhines’ first and second lower molars suggest that morphological stasis may explain the reduced molar shape variation observed. Platyrrhine lower molar shape might be a primitive retention of the ancestral state affected by strong ecological constraints throughout the radiation of the main platyrrhine families. The Patagonian fossil specimens showed two distinct morphological patterns of lower molars, Callicebus—like and Saguinus—like, which might be the precursors of the extant forms, whereas the Middle Miocene specimens, though showing morphological resemblances with the Patagonian fossils, also displayed new, derived molar patterns, Alouatta—like and Pitheciinae—like, thereby suggesting that despite the overall morphological stasis of molars, phenotypic diversification of molar shape was already settled during the Middle Miocene. PMID:27190704

External root resorption of the second molar associated with third molar impaction: comparison of panoramic radiography and cone beam computed tomography.

PubMed

Oenning, Anne Caroline Costa; Neves, Frederico Sampaio; Alencar, Phillipe Nogueira Barbosa; Prado, Rodrigo Freire; Groppo, Francisco Carlos; Haiter-Neto, Francisco

2014-08-01

The aim of the present study was to compare panoramic radiography and cone beam computed tomography (CBCT) for the assessment of external root resorption (ERR) of second molars associated with impacted third molars. In addition, the prevalence of ERR in second molars and the inclinations of the third molars more associated with ERR were investigated in both imaging methods. The sample consisted of 66 individuals with maxillary and mandibular impacted third molars (n = 188) seen on panoramic radiographs and CBCT images. The presence of ERR on the adjacent second molar was investigated, and the position of the third molar was determined using Winter's classification (vertical, horizontal, mesioangular, distoangular, and transverse). Statistical analysis was performed using the χ(2) test, Fisher exact test, and 2-proportion Z test (the significance level was set at 5%). A significantly greater number of cases of ERR (P < .0001) was diagnosed from CBCT images (n = 43, 22.88%) than panoramic radiographs (n = 10, 5.31%). The agreement between the panoramic radiographs and CBCT scans for diagnosing ERR was 4.3%. Mandibular third molars in mesioangular and horizontal inclinations were more likely to cause resorption of the adjacent teeth. CBCT should be indicated for the diagnosis of ERR in second molars when direct contact between the mandibular second and third molars has been observed on panoramic radiographs, especially in mesioangular or horizontal impactions. Furthermore, considering the propensity of these teeth to cause ERR in second molars, third molar prophylactic extraction could be suggested. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Banding versus bonding of first permanent molars: a multi-centre randomized controlled trial.

PubMed

Nazir, Mariyah; Walsh, Tanya; Mandall, Nicky A; Matthew, Susie; Fox, Dee

2011-06-01

To assess the effectiveness of banding versus bonding of first permanent molars during fixed appliance treatment; in terms of attachment failure, patient discomfort and post-treatment enamel demineralization. Multi-centre randomized clinical trial. One District General Hospital Orthodontic Department and two Specialist Orthodontic Practices. Orthodontic patients aged between 10 and 18 years old, randomly allocated to either receive molar bands (n=40) or molar bonds (n=40). Bands were cemented with a conventional glass ionomer cement and tubes were bonded with light-cured composite to all four first permanent molar teeth for each subject. Attachments were reviewed at each recall appointment to assess loosening or loss. The clinical end point of the trial was the day of appliance debond. Enamel demineralization at debond was assessed using the modified International Caries Assessment and Detection System (ICDAS). The first time failure rate for molar bonds was 18·4% and 2·6% for molar bands (P=0·0002). Survival analysis demonstrated molar bonds were more likely to fail compared with molar bands. First permanent molars with bonded tubes experienced more demineralization than those with cemented bands (P=0·027). There was no statistically significant difference in discomfort experienced by patients after banding or bonding first permanent molars (P>0·05). This study shows that as part of fixed appliance therapy, American Orthodontics photoetched first permanent molar bands cemented with 3M ESPE Ketac-Cem perform better than American Orthodontics low profile photo-etched and mesh-based first permanent molar tubes bonded with 3M Unitek Transbond XT in terms of failure behaviour and molar enamel demineralization.

Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes.

PubMed

Ebrahimi, Hossein Pasha; Hadi, Jabbar S; Abdulnabi, Zuhair A; Bolandnazar, Zeinab

2014-01-03

A new series of metal(II) complexes of Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) have been synthesized from a salen-type Schiff base ligand derived from o-vanillin and 4-methyl-1,2-phenylenediamine and characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR, (13)C NMR and EI-mass), molar conductance measurements and thermal analysis techniques. Coats-Redfern method has been utilized to calculate the kinetic and thermodynamic parameters of the metal complexes. The molecular geometry, Mulliken atomic charges of the studied compounds were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The theoretical (13)C chemical shift results of the studied compounds have been calculated at the B3LYP, PBEPBE and PW91PW91 methods and standard 6-311+G(d,p) basis set starting from optimized geometry. The comparison of the results indicates that B3LYP/6-311+G(d,p) yields good agreement with the observed chemical shifts. The measured low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. The spectral and thermal analysis reveals that all complexes have octahedral geometry except Cu(II) complex which can attain the square planner arrangement. The presence of lattice and coordinated water molecules are indicated by thermograms of the complexes. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps. Copyright © 2013 Elsevier B.V. All rights reserved.

The coupling of carbon dioxide and epoxides by phenanthroline derivatives containing different Cu(II) complexes as catalyst

NASA Astrophysics Data System (ADS)

Kilic, Ahmet; Palali, Ahmet Arif; Durgun, Mustafa; Tasci, Zeynep; Ulusoy, Mahmut

2013-09-01

A series of the mononuclear Cu(II) metal complexes containing the ligand Bdppz [(9a,13a-dihydro-4,5,9,14-tetraaza-benzo[b]triphenylene-11-yl)-phenyl-methanone] (L1) and Aqphen [(12,17-dihydronaphthol[2,3-h]dipyrido[3,2-a:2‧,3‧-c]-phenazine-12,17-dione)] (L2) were synthesized and used as catalyst for the coupling of carbon dioxide (CO2) and liquid epoxide which served as both reactant and solvent. Dimethylamino pyridine (DMAP) was used as co-catalyst. The yields of epoxides to corresponding cyclic carbonates were determined by comparing the ratio of product to substrate in the 1H NMR spectrum of an aliquot of the reaction mixture. The mononuclear Cu(II) complexes of these ligands were synthesized by treating an ethanol solvent of the appropriate ligand with a different molar amount of CuCl2·2H2O. The Cu(II) complexes were characterized by FT-IR, UV-Vis, elemental analysis, melting point analysis, mass spectra, molar conductivity measurements and magnetic susceptibility techniques. The reaction of the Bdppz and Aqphen ligands in a 1:1, 1:2 or 1:3 mole ratio with CuCl2·2H2O afforded ionic Cu(II) complexes in the presence of Et3N.

Non-covalent interactions in 2-methylimidazolium copper(II) complex (MeImH)2[Cu(pfbz)4]: Synthesis, characterization, single crystal X-ray structure and packing analysis

NASA Astrophysics Data System (ADS)

Sharma, Raj Pal; Saini, Anju; Kumar, Santosh; Kumar, Jitendra; Sathishkumar, Ranganathan; Venugopalan, Paloth

2017-01-01

A new anionic copper(II) complex, (MeImH)2 [Cu(pfbz)4] (1) where, MeImH = 2-methylimidazolium and pfbz = pentafluorobenzoate has been isolated by reacting copper(II) sulfate pentahydrate, pentafluorobenzoic acid and 2-methylimidazole in ethanol: water mixture in 1:2:2 molar ratio. This complex 1 has been characterized by elemental analysis, thermogravimetric analysis, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. The complex salt crystallizes in monoclinic crystal system with space group C2/c. Single crystal X-ray structure determination revealed the presence of discrete ions: [Cu(pfbz)4]2- anion and two 2-methylimidazolium cation (C4H7N2)+. The crystal lattice is stabilized by strong hydrogen bonding and F⋯F interactions between cationic-anionic and the anionic-anionic moieties respectively, besides π-π interactions.

Dental computed tomographic imaging as age estimation: morphological analysis of the third molar of a group of Turkish population.

PubMed

Cantekin, Kenan; Sekerci, Ahmet Ercan; Buyuk, Suleyman Kutalmis

2013-12-01

Computed tomography (CT) is capable of providing accurate and measurable 3-dimensional images of the third molar. The aims of this study were to analyze the development of the mandibular third molar and its relation to chronological age and to create new reference data for a group of Turkish participants aged 9 to 25 years on the basis of cone-beam CT images. All data were obtained from the patients' records including medical, social, and dental anamnesis and cone-beam CT images of 752 patients. Linear regression analysis was performed to obtain regression formulas for dental age calculation with chronological age and to determine the coefficient of determination (r) for each sex. Statistical analysis showed a strong correlation between age and third-molar development for the males (r2 = 0.80) and the females (r2 = 0.78). Computed tomographic images are clinically useful for accurate and reliable estimation of dental ages of children and youth.

Creating three-dimensional tooth models from tomographic images.

PubMed

Lima da Silva, Isaac Newton; Barbosa, Gustavo Frainer; Soares, Rodrigo Borowski Grecco; Beltrao, Maria Cecilia Gomes; Spohr, Ana Maria; Mota, Eduardo Golcalves; Oshima, Hugo Mitsuo Silva; Burnett, Luiz Henrique

2008-01-01

The use of Finite Element Analysis (FEA) is becoming very frequent in Dentistry. However, most of the three-dimensional models presented by the literature for teeth are limited in terms of geometry. Discrepancy in shape and dimensions can cause wrong results to occur. Sharp cusps and faceted contour can produce stress concentrations, which are incoherent with the reality. The aim of this study was the processing of tomographic images in order to develop an advanced three-dimensional reconstruction of the anatomy of a molar tooth and the integration of the resulting solid with commercially available CAD/CAE software. Computed tomographic images were obtained from 0.5 mm thick slices of mandibular molar and transferred to commercial cad software. Once the point cloud data have been generated, the work on these points started to get to the solid model of the tooth with Pro/Engineer software. The obtained tooth model showed very accurate shape and dimensions, as it was obtained from real tooth data with error of 0.0 to -0.8 mm. The methodology presented was efficient for creating a biomodel of a tooth from tomographic images that realistically represented its anatomy.

Synthesis and characterization of TiC nanopowders via sol-gel and subsequent carbothermal reduction process

NASA Astrophysics Data System (ADS)

Chen, Xu; Fan, Jinglian; Lu, Qiong

2018-06-01

TiC nanocrystalline powders were synthesized by in-situ carbothermic reduction of Ti-O-C precursor under vacuum atmosphere. And the Ti-O-C precursor was formed by sol-gel method from titanium butyrate (TBOT) and sucrose. To obtain stable sol, TBOT was directly added into mixed solution which contains water, sucrose, acetic acid (AcOH) and acetylacetone (ACAC). This procedure is more convenient and economical because it avoids the use of alcohol which is used as solvent in most reports of alkoxide hydrolysis sol-gel method. TG-DSC, XRD, FTIR and SEM/TEM were employed to analyze and characterize the product during the entire process. The phase composition and crystalline structure parameters of powders with different C/Ti molar ratio were investigated by Rietveld refinement method, and elemental quantitative analysis of the samples were performed. Furthermore, the optimal parameters of carbothermal reduction were obtained and the grain growth mechanism was demonstrated. The results show that TiC nanocrystalline powders (C/Ti molar ratio is 3.5 in the precursor) were synthesized at 1300 °C for 2 h, which have near standard lattice parameter, well crystallinity and fine average grain size ( 37.4 nm).

Role of multiple cusps in tooth fracture.

PubMed

Barani, Amir; Bush, Mark B; Lawn, Brian R

2014-07-01

The role of multiple cusps in the biomechanics of human molar tooth fracture is analysed. A model with four cusps at the bite surface replaces the single dome structure used in previous simulations. Extended finite element modelling, with provision to embed longitudinal cracks into the enamel walls, enables full analysis of crack propagation from initial extension to final failure. The cracks propagate longitudinally around the enamel side walls from starter cracks placed either at the top surface (radial cracks) or from the tooth base (margin cracks). A feature of the crack evolution is its stability, meaning that extension occurs steadily with increasing applied force. Predictions from the model are validated by comparison with experimental data from earlier publications, in which crack development was followed in situ during occlusal loading of extracted human molars. The results show substantial increase in critical forces to produce longitudinal fractures with number of cuspal contacts, indicating a capacity for an individual tooth to spread the load during mastication. It is argued that explicit critical force equations derived in previous studies remain valid, at the least as a means for comparing the capacity for teeth of different dimensions to sustain high bite forces. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparative stress distribution of implant-retained mandibular ball-supported and bar-supported overlay dentures: a finite element analysis.

PubMed

Vafaei, Fariborz; Khoshhal, Masoumeh; Bayat-Movahed, Saeed; Ahangary, Ahmad Hassan; Firooz, Farnaz; Izady, Alireza; Rakhshan, Vahid

2011-08-01

Implant-retained mandibular ball-supported and bar-supported overlay dentures are the two most common treatment options for the edentulous mandible. The superior option in terms of strain distribution should be determined. The three-dimensional model of mandible (based on computerized tomography scan) and its overlying implant-retained bar-supported and ball-supported overlay dentures were simulated using SolidWorks, NURBS, and ANSYS Workbench. Loads A (60 N) and B (60 N) were exerted, respectively, in protrusive and laterotrusive motions, on second molar mesial, first molar mesial, and first premolar. The strain distribution patterns were assessed on (1) implant tissue, (2) first implant-bone, and (3) second implant-bone interfaces. Protrusive: Strain was mostly detected in the apical of the fixtures and least in the cervical when bar design was used. On the nonworking side, however, strain was higher in the cervical and lower in the apical compared with the working side implant. Laterotrusive: The strain values were closely similar in the two designs. It seems that both designs are acceptable in terms of stress distribution, although a superior pattern is associated with the application of bar design in protrusive motion.

Three-Dimensional Finite Element Analysis of Stress Distribution and Displacement of the Maxilla Following Surgically Assisted Rapid Maxillary Expansion with Tooth- and Bone-Borne Devices.

PubMed

Dalband, Mohsen; Kashani, Jamal; Hashemzehi, Hadi

2015-04-01

The aim of this study was to investigate the displacement and stress distribution during surgically assisted rapid maxillary expansion under different surgical conditions with tooth- and bone-borne devices. Three-dimensional (3D) finite element model of a maxilla was constructed and an expansion force of 100 N was applied to the left and right molars and premolars with tooth-borne devices and the left and right of mid-palatal sutures at the first molar level with bone-borne devices. Five computer-aided design (CAD) models were simulated as follows and surgical procedures were used: G1: control group (without surgery); G2: Le Fort I osteotomy; G3: Le Fort I osteotomy and para-median osteotomy; G4: Le Fort I osteotomy and pterygomaxillary separation; and G5: Le Fort I osteotomy, para-median osteotomy, and pterygomaxillary separation. Maxillary displacement showed a gradual increase from G1 to G5 in all three planes of space, indicating that Le Fort I osteotomy combined with para-median osteotomy and pterygomaxillary separation produced the greatest displacement of the maxilla with both bone- and tooth-borne devices. Surgical relief and bone-borne devices resulted in significantly reduced stress on anchored teeth. Combination of Le Fort I and para-median osteotomy with pterygomaxillary separation seems to be an effective procedure for increasing maxillary expansion, and excessive stress side effects are lowered around the anchored teeth with the use of bone-borne devices.

Asymmetric Outer Bow Length and Cervical Headgear Force System: 3D Analysis Using Finite Element Method

PubMed Central

Geramy, Allahyar; Hassanpour, Mehdi; Emadian Razavi, Elham sadat

2015-01-01

Objectives: This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths. Materials and Methods: Four 3D finite element method (FEM) models of a cervical headgear attached to the maxillary first molars were designed in SolidWorks 2010 software and transferred to ANSYS Workbench ver. 11 software. Models contained the first molars, their periodontal ligament (PDL), cancellous and cortical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with differences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer. Results: The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm). Conclusion: As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment. Clinical Relevance: A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use. PMID:26622275

Risk factors associated with oroantral perforation during surgical removal of maxillary third molar teeth.

PubMed

Hasegawa, Takumi; Tachibana, Akira; Takeda, Daisuke; Iwata, Eiji; Arimoto, Satomi; Sakakibara, Akiko; Akashi, Masaya; Komori, Takahide

2016-12-01

The relationship between radiographic findings and the occurrence of oroantral perforation is controversial. Few studies have quantitatively analyzed the risk factors contributing to oroantral perforation, and no study has reported multivariate analysis of the relationship(s) between these various factors. This retrospective study aims to fill this void. Various risk factors for oroantral perforation during maxillary third molar extraction were investigated by univariate and multivariate analysis. The proximity of the roots to the maxillary sinus floor (root-sinus [RS] classification) was assessed using panoramic radiography and classified as types 1-5. The relationship between the maxillary second and third molars was classified according to a modified version of the Archer classification. The relative depth of the maxillary third molar in the bone was classified as class A-C, and its angulation relative to the long axis of the second molar was also recorded. Performance of an incision (OR 5.16), mesioangular tooth angulation (OR 6.05), and type 3 RS classification (i.e., significant superimposition of the roots of all posterior maxillary teeth with the sinus floor; OR 10.18) were all identified as risk factors with significant association to an outcome of oroantral perforation. To our knowledge, this is the first multivariate analysis of the risk factors for oroantral perforation during surgical extraction of the maxillary third molar. This RS classification may offer a new predictive parameter for estimating the risk of oroantral perforation.

[Effect of premolar extractions on third molar angulation changes: a meta-analysis].

PubMed

Fan, Linlin; Kuang, Qin; Tang, Yujuan; Qin, Pu

2015-03-01

To assess the effect of premolar extractions on third molar angulation changes in orthodontic patients. The Cochrane library, PubMed, Embase, China Science and Technology Periodical Database, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM) and Wanfang database were searched from January 1, 1990 to May 20, 2014 to identify all the studies about third molar angulation changes in orthodontic patients with or without premolars extraction, which was assigned as a extraction group and a control group. Th e extraction group was further divided into a fi rst premolar extraction subgroup and a second premolar extraction subgroup. Literature filtering, data extraction and methodological quality evaluation were finished independently by two researchers. After cross checking, the disagreements were solved by discussion. Meta-analysis was carried out by RevMan 5.3.3 software. Ten studies involving 712 patients were included. Meta-analysis revealed that: compared with the control group, the changes of third molar angulation in maxillary and mandible in the extraction group were statistically significantly different (all P<0.05); the difference in angulation between the two groups was about 5.19° in maxillary and 3.55° in mandibul. As for the premolar extraction subgroups, there was no significant difference in mandibular third molar angulation between them (P>0.05). The orthodontic treatment involving first or second premolar extractions can improve the maxillary third molar angulation, and the second premolar extraction is the best option.

Transition Metal Complexes of Quinolino[3,2-b]benzodiazepine and Quinolino[3,2-b]benzoxazepine: Synthesis, Characterization, and Antimicrobial Studies

PubMed Central

Basavaraju, B.; Bhojya Naik, Halehatty S.; Prabhakara, Mustur C.

2007-01-01

The synthesis and characterization of title complexes of the ligand Quinolino[3,2-b]benzodiazepine (QBD) and Quinolino[3,2-b]benzoxazepine (QBO) are reported. The complexes have been characterized by elemental analysis, molar conductance, magnetic studies, IR, H1 NMR, and UV-visible studies. They have the stoichiometry [ML2C12], where M=Co(II)/Ni(II), L=QBD/QBO, and [MLC12], where M=Zn(II)/Cd(II), L=QBD/QBO. The antibacterial and antifungal activity of the metal complexes has been investigated. The complexes were found to have higher antimicrobial activity than the parent ligand. PMID:18273383

Synthesis, Spectroscopic, and Antimicrobial Studies on Bivalent Nickel and Copper Complexes of Bis(thiosemicrbazone)

PubMed Central

Chandra, Sulekh; Raizada, Smriti; Tyagi, Monika; Gautam, Archana

2007-01-01

A series of metal complexes of Cu(II) and Ni(II) having the general composition [M(L)X2] with benzil bis(thiosemicarbazone) has been prepared and characterized by element chemical analysis, molar conductance, magnetic susceptibility measurements, and spectral (electronic, IR, EPR, mass) studies. The IR spectral data suggest the involvement of sulphur and azomethane nitrogen in coordination to the central metal ion. On the basis of spectral studies, an octahedral geometry has been assigned for Ni(II) complexes but a tetragonal geometry for Cu(II) complexes. The free ligand and its metal complexes have been tested in vitro against a number of microorganisms in order to assess their antimicrobial properties. PMID:18273385

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage.

PubMed

Kinzinger, Gero S M; Fritz, Ulrike B; Sander, Franz-Günter; Diedrich, Peter R

2004-01-01

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG 1 (18 patients), eruption of the second molars had either not yet taken place or was not complete. In PG 2 (15 patients), the second molars had already developed as far as the occlusal plane, with the third molars at the budding stage. In PG 3 (3 patients), germectomy of the wisdom teeth had been carried out, and the first and second molars on both sides had completely erupted. Analysis of cephalograms to identify any changes in the sagittal plane showed that, in the direction of distalization, a tooth bud acts on the mesial neighboring tooth like a fulcrum, and that tipping of the first molars in patients in whom the second molar was still at the budding stage was thus greater. In patients whose second molars had erupted completely, the degree of tipping was greater again when a third molar bud was located in the direction of movement. After previously completed germectomy of the wisdom teeth, almost exclusively bodily distalization of both molars is possible, even without bands being applied to the second molars. However, if the first and second molars are distalized simultaneously with a pendulum appliance, the duration of therapy will be longer, greater forces will have to be applied, and more anchorage will be lost. Statistical analysis of the results of dental-angular measurements showed significant differences in the degree of molar tipping and reciprocal incisor protrusion. The degree of distal tipping of first molars was less in patients with erupted second molars (PG 2 and PG 3) than in those whose second molars were not yet erupted (PG 1). For instance, the measured angles were 0.9 degrees +/- 3.43 degrees (to the palatal plane) and 0.8 degrees +/- 3.4 degrees (to the anterior cranium floor) in PG 2, and -0.33 degrees +/- 0.58 degrees and 0.67 degrees +/- 2.08 degrees, respectively, in PG 3, contrasting with respective values of 5.89 degrees +/- 3.74 degrees and 5.36 degrees +/- 3.49 degrees in PG 1. Tipping of erupted second molars was much more marked in PG 2 (7.92 degrees +/- 5.83 degrees to the palatal plane and 7.55 degrees +/- 5.28 degrees to the anterior cranium floor), but much less pronounced in PG 3 (2 degrees +/- 1.73 degrees to the palatal plane and 2 degrees +/- 2 degrees to the anterior cranium floor) than the corresponding movement of the second budding-stage molars in PG 1 (4.06 degrees +/- 2.15 degrees and 3.97 degrees +/- 2.27 degrees, respectively). The degree of incisor protrusion occurring reciprocally with molar distalization was much less in these patients (measured angles of 3.28 degrees +/- 1.97 degrees and 2.89 degrees +/- 2.17 degrees to the palatal plane and anterior cranium floor, respectively) than in the patients presenting different stages of the dentition (angles of 5.5 degrees +/- 3.33 degrees and 6.03 degrees +/- 4.29 degrees, respectively, in PG 2, and angles of 5.5 degrees +/- 3.28 degrees and 6.67 degrees +/- 3.09 degrees, respectively, in PG 3). Moreover, measurement of dental casts in the horizontal plane showed not only the targeted mesiobuccal rotation of both maxillary molars, but also a vestibular drift of the unbanded second molars.

Thermal and volumetric properties of methanol-hexamethylphosphortriamide mixtures under standard conditions

NASA Astrophysics Data System (ADS)

Batov, D. V.; Kustov, A. V.; Antonova, O. A.; Smirnova, N. L.

2017-02-01

Enthalpic and volumetric characteristics of mixing in a methanol (MeOH)-hexamethylphosphortriamide (HMPT, 2) mixture are studied. Based on an analysis of concentration changes in the obtained data and the calculated partial molar characteristics, it is shown that at 0.2 molar fractions > x 2 > 0.7 molar fractions, the variation in the composition of the mixture slightly alters the character of intermolecular interactions characteristic of pure components. It is found that MeOH-HMPT mixtures experience most changes in intermolecular interaction and structure within the range of 0.2-0.7 molar fractions of HMPT.

The Relation Between Dermatoglyphics And Mesiodistal Width Of The Deciduous Second Molar And Permanent First Molar

PubMed Central

Kumar, Vinod; Adusumilli, Hamsini; Reddy, KM Parveen; Kumar, NH Praveen

2017-01-01

Introduction Dermatoglyphics is one of the important diagnostic tools used in the recent days for identification of an individual. Dermatoglyphics is the study of type of patterns present on digits, palms and foot. The mesiodistal diameter of the tooth is an important factor which reveals the tooth-bone discrepancy. Deciduous second molar and permanent first molar exhibit least degree of variation. Both the dermal ridges and the enamel layer of the tooth originate from ectodermal layer and during the same period of intrauterine life. Aim To determine and compare the dermatoglyphics with the mesiodistal width of the deciduous second molar and permanent first molar. Materials and Methods A sample of 120 child ranaged between 6-12 years were included in the study whose digital and palmer traits were recorded using ink method and the mesiodistal widths of the deciduous second molar and permanent first molar were recorded using a vernier caliper. The data was subjected to statistical analysis using unpaired t test. Results The ‘ATD’ angle was found in the range of 40°-50°. The loop patterns were more common followed by whorls and arch patterns. Girls expressed a greater mesiodistal diameter of deciduous second molar than boys. No significant correlation was found in between the dermatoglyphics and tooth size. Conclusion There was no significant correlation between the finger print patterns, ‘ATD’ angle and the mesiodistal diameter of the deciduous second molar and the permanent first molar. PMID:28969275

Association between the presence of a partially erupted mandibular third molar and the existence of caries in the distal of the second molars.

PubMed

Falci, S G M; de Castro, C R; Santos, R C; de Souza Lima, L D; Ramos-Jorge, M L; Botelho, A M; Dos Santos, C R R

2012-10-01

The objective of this study was to verify, using periapical radiographs, whether a partially erupted mandibular third molar is a factor in the presence of dental caries on the distal surface of the adjacent second molar. Two-forty six high quality periapical radiographs were selected, each showing a partially erupted mandibular third molar. The variables analyzed were: tooth number; gender; age; radiographic presence of caries on the distal surface of the adjacent molar; Pell and Gregory classification; Winter classification; angulation and distance between the second and mandibular third molar. The examiners were previously calibrated to collect data (kappa statistics from 0.87 to 1.0). The prevalence rate of caries on the distal surface of the second molar was 13.4%. In the logistical multivariate regression analysis, the angulation (OR=8.5; IC95%: 1.7-43.8; p=0.011) and the gender (OR=3.3; IC95%: 1.4-7.7; p=0.005) remained statistically significant after an age adjustment was made. The results indicate that the presence of a partially erupted mandibular third molar with an angulation of 31 degrees or more, is a risk factor for caries on the distal surface of the mandibular second molars. Copyright © 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

The role of microbial iron reduction in the formation of Proterozoic molar tooth structures

NASA Astrophysics Data System (ADS)

Hodgskiss, Malcolm S. W.; Kunzmann, Marcus; Poirier, André; Halverson, Galen P.

2018-01-01

Molar tooth structures are poorly understood early diagenetic, microspar-filled voids in clay-rich carbonate sediments. They are a common structure in sedimentary successions dating from 2600-720 Ma, but do not occur in rocks older or younger, with the exception of two isolated Ediacaran occurrences. Despite being locally volumetrically significant in carbonate rocks of this age, their formation and disappearance in the geological record remain enigmatic. Here we present iron isotope data, supported by carbon and oxygen isotopes, major and minor element concentrations, and total organic carbon and sulphur contents for 87 samples from units in ten different basins spanning ca. 1900-635 Ma. The iron isotope composition of molar tooth structures is almost always lighter (modal depletion of 2‰) than the carbonate or residue components in the host sediment. We interpret the isotopically light iron in molar tooth structures to have been produced by dissimilatory iron reduction utilising Fe-rich smectites and Fe-oxyhydroxides in the upper sediment column. The microbial conversion of smectite to illite results in a volume reduction of clay minerals (∼30%) while simultaneously increasing pore water alkalinity. When coupled with wave loading, this biogeochemical process is a viable mechanism to produce voids and subsequently precipitate carbonate minerals. The disappearance of molar tooth structures in the mid-Neoproterozoic is likely linked to a combination of a decrease in smectite abundance, a decline in the marine DIC reservoir, and an increase in the concentration of O2 in shallow seawater.

Summaries of Research, Fiscal Year 1990

DTIC Science & Technology

1991-04-01

identification of third molars at risk to develop pcricoronitis. Data on 324 patients were collected relating to complications associated to the...extraction of third molars . A report was submitted to the Chief, Navy Dental Corps on 31 March 1990 following preliminary data analysis. An abstract has been...Cohen, M. E., Arthur, J. S. and Rodden, J. W. Patients’ Retrospective Preference for Extraction of Asymptomatic Third Molars . Community Dentistry and

Demirjian's method in the estimation of age: A study on human third molars

PubMed Central

Lewis, Amitha J.; Boaz, Karen; Nagesh, K. R; Srikant, N; Gupta, Neha; Nandita, K. P; Manaktala, Nidhi

2015-01-01

Aim: The primary aim of the following study is to estimate the chronological age based on the stages of third molar development following the eight stages (A to H) method of Demirjian et al. (along with two modifications-Orhan) and secondary aim is to compare third molar development with sex and age. Materials and Methods: The sample consisted of 115 orthopantomograms from South Indian subjects with known chronological age and gender. Multiple regression analysis was performed with chronological age as the dependable variable and third molar root development as independent variable. All the statistical analysis was performed using the SPSS 11.0 package (IBM ® Corporation). Results: Statistically no significant differences were found in third molar development between males and females. Depending on the available number of wisdom teeth in an individual, R2 varied for males from 0.21 to 0.48 and for females from 0.16 to 0.38. New equations were derived for estimating the chronological age. Conclusion: The chronological age of a South Indian individual between 14 and 22 years may be estimated based on the regression formulae. However, additional studies with a larger study population must be conducted to meet the need for population-based information on third molar development. PMID:26005306

Effect of molarity on sol-gel routed nano TiO2 thin films

NASA Astrophysics Data System (ADS)

Lourduraj, Stephen; Williams, Rayar Victor

The nanostructured titanium dioxide (TiO2) thin films have been prepared for the molar concentrations of titanium tetra isopropoxide (TTIP) 0.05M, 0.1M, 0.15M and 0.2M by sol-gel routed spin coating technique with calcination at 450∘C. The processing parameters such as, pH value (8), catalyst HCl (0.1ml), spin speed (3000rpm) and calcination temperature (450∘C) are optimized. The crystalline nature and surface morphology were analyzed by XRD, SEM and AFM analysis. The XRD results confirm that the films are crystalline with anatase phase, and are nanostructured. The SEM micrographs of the TiO2 film reveal the spherical nature of the particle. AFM analysis establishes that the uniformity of the TiO2 thin film was optimized at 0.2M. The optical measurements show that the transmittance depends on the molarity, and the optical band gap energy of TiO2 films is found to be inversely proportional to molarity. The I-V characteristics exhibit that the molarity strongly influences the electrical conductivity of the film. The results indicate that the significant effect of molarity on structural, optical and electrical properties of the nanostructured TiO2 thin films will be useful to photovoltaic application.

Coronectomy of impacted mandibular third molars: A meta-analysis and systematic review of the literature

PubMed Central

Cervera-Espert*, Juan; Pérez-Martínez*, Sara; Cervera-Ballester, Juan; Penarrocha-Oltra, David

2016-01-01

Background Coronectomy is an alternative to complete removal of an impacted mandibular third molar. Most authors have recommended coronectomy to prevent damage to the inferior alveolar nerve during surgical extraction of lower third molars. The present study offers a systematic review and metaanalysis of the coronectomy technique. Material and Methods A systematic review and meta-analysis was performed based on a PubMed and Cochrane databases search for articles published from 2014 and involving coronectomy of mandibular third molars located near the inferior alveolar nerve canal, with a minimum of 10 cases and a minimum follow-up period of 6 months. After application of the inclusion and exclusion criteria, a total of 12 articles were included in the study. Results and Discussion Coronectomy results in significantly lesser loss of sensitivity of the inferior alveolar nerve and prevents the occurrence of dry socket. No statistically significant differences were observed in the incidence of pain and infection between coronectomy and complete surgical extraction. After coronectomy, the remaining tooth fragment migrates an average of 2 mm within two years. Conclusions Coronectomy is indicated when the mandibular third molar is in contact with the inferior alveolar nerve and complete removal of the tooth may cause nerve damage. Key words:Coronectomy, included third molar, inferior alveolar nerve injury. PMID:27031064

The Uranium from Seawater Program at the Pacific Northwest National Laboratory: Overview of Marine Testing, Adsorbent Characterization, Adsorbent Durability, Adsorbent Toxicity, and Deployment Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, Gary A.; Kuo, Li-Jung; Janke, Chris J.

The Pacific Northwest National Laboratory’s (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 ± 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 ± 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage« less

One year Survival Rate of Ketac Molar versus Vitro Molar for Occlusoproximal ART Restorations: a RCT.

PubMed

Anna Luisa de Brito, Pacheco; Isabel Cristina, Olegário; Clarissa Calil, Bonifácio; Ana Flávia Bissoto, Calvo; José Carlos Pettorossi, Imparato; Daniela Prócida, Raggio

2017-11-06

Good survival rates for single-surface Atraumatic Restorative Treatment (ART) restorations have been reported, while multi-surface ART restorations have not shown similar results. The aim of this study was to evaluate the survival rate of occluso-proximal ART restorations using two different filling materials: Ketac Molar EasyMix (3M ESPE) and Vitro Molar (DFL). A total of 117 primary molars with occluso-proximal caries lesions were selected in 4 to 8 years old children in Barueri city, Brazil. Only one tooth was selected per child. The subjetcs were randomly allocated in two groups according to the filling material. All treatments were performed following the ART premises and all restorations were evaluated after 2, 6 and 12 months. Restoration survival was evaluated using Kaplan-Meier survival analysis and Log-rank test, while Cox regression analysis was used for testing association with clinical factors (α = 5%). There was no difference in survival rate between the materials tested, (HR = 1.60, CI = 0.98-2.62, p = 0.058). The overall survival rate of restorations was 42.74% and the survival rate per group was Ketac Molar = 50,8% and Vitro Molar G2 = 34.5%). Cox regression test showed no association between the analyzed clinical variables and the success of the restorations. After 12 months evaluation, no difference in the survival rate of ART occluso-proximal restorations was found between tested materials.

The inter-relationship between dietary and environmental properties and tooth wear: comparisons of mesowear, molar wear rate, and hypsodonty index of extant Sika deer populations.

PubMed

Kubo, Mugino Ozaki; Yamada, Eisuke

2014-01-01

In reference to the evolutionary trend of increasing cheek tooth height in herbivorous ungulates, the causes of dental abrasion have long been debated. Interspecific comparisons of extant ungulates have revealed that both phytoliths in grass and external abrasive matter may play important roles. Using analysis of extant sika deer living in various environments and showing continuous latitudinal variation in food habits from northern grazing to southern browsing, we quantitatively evaluated the influence of dietary and environmental properties on three dental variables: mesowear score (MS), molar wear rate, and M3 hypsodonty index. We used 547 skulls and 740 mandibles from 16 populations of sika deer to obtain the dental measurements. We found that only graminoid proportion in diet correlated with MS and the molar wear rate, implying that phytoliths in grass abrade dental tissues. In contrast, annual precipitation in habitat was not correlated with any of the dental variables. We also found a significant correlation between the molar wear rate (selective pressure for high-crowned molars) and the M3 hypsodonty index of extant sika deer, implying an evolutionary increment in molar height corresponding to the molar wear rate. Our intraspecific comparative analyses provide further support for use of mesowear analysis as a paleodiet estimation method; it not only reveals staple food types (graminoids or dicots) but also implies regional or seasonal variation in the diet of the species.

The Inter-Relationship between Dietary and Environmental Properties and Tooth Wear: Comparisons of Mesowear, Molar Wear Rate, and Hypsodonty Index of Extant Sika Deer Populations

PubMed Central

Kubo, Mugino Ozaki; Yamada, Eisuke

2014-01-01

In reference to the evolutionary trend of increasing cheek tooth height in herbivorous ungulates, the causes of dental abrasion have long been debated. Interspecific comparisons of extant ungulates have revealed that both phytoliths in grass and external abrasive matter may play important roles. Using analysis of extant sika deer living in various environments and showing continuous latitudinal variation in food habits from northern grazing to southern browsing, we quantitatively evaluated the influence of dietary and environmental properties on three dental variables: mesowear score (MS), molar wear rate, and M3 hypsodonty index. We used 547 skulls and 740 mandibles from 16 populations of sika deer to obtain the dental measurements. We found that only graminoid proportion in diet correlated with MS and the molar wear rate, implying that phytoliths in grass abrade dental tissues. In contrast, annual precipitation in habitat was not correlated with any of the dental variables. We also found a significant correlation between the molar wear rate (selective pressure for high-crowned molars) and the M3 hypsodonty index of extant sika deer, implying an evolutionary increment in molar height corresponding to the molar wear rate. Our intraspecific comparative analyses provide further support for use of mesowear analysis as a paleodiet estimation method; it not only reveals staple food types (graminoids or dicots) but also implies regional or seasonal variation in the diet of the species. PMID:24603896

An experimental study of arch perimeter and arch width increase with mandibular expansion: a finite element method.

PubMed

Baswaraj; Hemanth, M; Jayasudha; Patil, Chandrashekhargouda; Sunilkumar, P; Raghuveer, H P; Chandralekha, B

2013-01-01

The objective of this study was to estimate the increase in arch perimeter associated with mandibular lateral expansion, To estimate the increase in intermolar width with mandibular lateral expansion and to find out the changes of tooth inclination with mandibular expansion. The mandibular bone with dentition of indian skeletal specimen was obtained. The computer tomogram (CT) slices of the mandible were taken. Finite element model (FEM): Numerical representation of the geometry was created by dividing the geometry into finite number of elements and the elements were connected together with nodes at the junction. The result of the study showed when 10° of lateral expansion was applied to the lower buccal segment at the center of rotation found at 4.3 mm below the root apex of first molar, a space of 1.3 mm between the canine and first premolar, and thus an increase in arch perimeter of 2.6 mm. The tip of the mesiolingual cusp of the first molar moved 4.2 mm laterally, resulting in a change in intermolar width by 8.4 mm. Three-dimensional simulation showed that 1 mm of intermolar expansion increased the arch perimeter by 0.30 mm. As the finite element method evolves and scientists are able to more clearly define physical properties of biological tissues, more accurate information can be generated at the level that other analytical methods cannot fully provide data.This result would be of value clinically for prediction of the effects of mandibular expansion.

Systemic Inflammation after Third Molar Removal: A Case-Control Study.

PubMed

Graziani, F; D'Aiuto, F; Gennai, S; Petrini, M; Nisi, M; Cirigliano, N; Landini, L; Bruno, R M; Taddei, S; Ghiadoni, L

2017-12-01

Third molar extraction is one of the most frequent interventions in dentistry. Nevertheless, there is scarce evidence on the host response of individuals with impacted or semi-impacted third molars and the possible effects of surgical removal. A case-control study of 40 patients was designed to evaluate 1) the differences in biomarkers of systemic inflammation, vascular function, and metabolism (high-sensitive C-reactive protein, lipids, fibrinogen, oxidative stress, and endothelial function analysis) and 2) the acute and short-term effects of surgical removal in patients with bilateral impacted or semi-impacted third molars compared to controls with no third molars. Patients undergoing third molar extraction exhibited greater levels of systemic inflammation, oxidative stress, and triglycerides than controls. Raised white blood cell counts as well as peaks of serum levels of C-reactive protein and fibrinogen were noticed in the first postoperative week. Three months after the extraction, all markers returned to baseline values. Malondialdehyde, an indicator of oxidative stress indicator, was significantly reduced after third molar removal. Semi-impacted or impacted third molars are associated with higher systemic inflammation, and their removal may represent a useful human model to study acute inflammation and determine beneficial systemic effects ( ClinicalTrials.gov NCT03048175).

Influence of unilateral maxillary first molar extraction treatment on second and third molar inclination in Class II subdivision patients.

PubMed

Livas, Christos; Pandis, Nikolaos; Booij, Johan Willem; Halazonetis, Demetrios J; Katsaros, Christos; Ren, Yijin

2016-01-01

To assess the maxillary second molar (M2) and third molar (M3) inclination following orthodontic treatment of Class II subdivision malocclusion with unilateral maxillary first molar (M1) extraction. Panoramic radiographs of 21 Class II subdivision adolescents (eight boys, 13 girls; mean age, 12.8 years; standard deviation, 1.7 years) before treatment, after treatment with extraction of one maxillary first molar and Begg appliances and after at least 1.8 years in retention were retrospectively collected from a private practice. M2 and M3 inclination angles (M2/ITP, M2/IOP, M3/ITP, M3/IOP), constructed by intertuberosity (ITP) and interorbital planes (IOP), were calculated for the extracted and nonextracted segments. Random effects regression analysis was performed to evaluate the effect on the molar angulation of extraction, time, and gender after adjusting for baseline measurements. Time and extraction status were significant predictors for M2 angulation. M2/ITP and M2/IOP decreased by 4.04 (95% confidence interval [CI]: -6.93, 1.16; P  =  .001) and 3.67 (95% CI: -6.76, -0.58; P  =  .020) in the extraction group compared to the nonextraction group after adjusting for time and gender. The adjusted analysis showed that extraction was the only predictor for M3 angulation that reached statistical significance. M3 mesial inclination increased by 7.38° (95% CI: -11.2, -3.54; P < .001) and 7.33° (95% CI: -11.48, -3.19; P  =  .001). M2 and M3 uprighting significantly improved in the extraction side after orthodontic treatment with unilateral maxillary M1 extraction. There was a significant increase in mesial tipping of maxillary second molar crowns over time.

Rare Complication in Third Maxillary Molar Extraction: Dislocation in Infratemporal Fossa.

PubMed

Battisti, Andrea; Priore, Paolo; Giovannetti, Filippo; Barbera, Giorgio; D'Alessandro, Francesco; Valentini, Valentino

2017-10-01

Removal of impacted third maxillary molar is frequently carried out without difficulties and low rate of intraoperative complications. The rare and particularly challenger to manage it is the third molar dislocation into the infratemporal fossa (IF). In this clinical report, the authors present their solution to manage and resolve this particular complication. A 28-year-old woman was referred to the emergency rescue unit of the authors' hospital by her dentistry, after the attempt to extract the left impacted maxillary third molar. During the procedure the tooth accidentally dislodged and was lost sight of it. The patient had significant mouth-opening limitation, omolateral mid face swelling and pain. Computer tomography was immediately performed to determine the exact position of the tooth, showing the dental element dislocated into the IF. Considering all of possible complications the best surgical option must guarantee a direct approach and a constant eye contact of the tooth, even in case of further displacement during the procedure, and allow early surgery. The authors used an endoscopic transoral approach through the preexisted access and solved all the issues reducing morbidity. Removing tooth from the IF could be burdened by serious risk of bleeding and/or nerve injury. The endoscopic approach provides direct view of the IF reducing morbidity.

[The effects of topical fluoridation of Ketac Molar Aplicap glass-ionomer material on the growth of cariogenic bacteria contained in the dental plaque].

PubMed

Płuciennik-Stronias, Małgorzata; Zarzycka, Beata; Bołtacz-Rzepkowska, Elzbieta

2013-01-01

Dental caries is a bacterial disease. The most important element used in caries prevention is fluoride, which is derived from the air, diet or fluoride-containing preparations and materials, e.g. glass-ionomer restorations. Modern fluoride-containing restorative materials are capable of releasing fluoride to the environment. Fluoride can be also accumulated in glass-ionomer cements, thus an attempt was made to saturate these materials with fluoride. The aim of the study was to evaluate the effect of topical fluoridation of Ketac Molar Aplicap glass-ionomer cement on the growth of Lactobacillus spp. in the dental plaque. The study was carried out in 15 patients with good oral hygiene, in whom 35 fillings with conventional glass-ionomer material, Ketac Molar Aplicap, were performed. After 6 months, three-day dental plaque from these fillings was examined. Next, fluoride was rubbed on the glass-ionomer surface and the examination of three-day dental plaque was repeated. No statistically significant differences (p = 0.143) in the amounts of Lactobacillus spp. in the plaque collected prior to and after topical fluoridation were revealed. Fluoride rubbed in the conventional glass-ionomer cement, Ketac Molar Aplicap, did not affect the amount of Lactobacillus spp. in the dental plaque growing on this material.

Factors associated with mandibular third molar eruption and impaction.

PubMed

Tsai, Hung-Huey

2005-01-01

A retrospective study, using panoramic radiographs, was conducted on 152 Taiwanese (72 males and 80 females) to investigate mandibular third molar eruption and impaction. The following measurements were made: inclinations and mesiodistal crown widths of the mandibular molars, vertical and horizontal spaces between the distal surface of the second molar and the anterior surface of the ramus, lengths and widths of the mandibular ramus and body, the ramus inclination, the mandibular plane angle, and the mandibular gonial angle. Differences between non-impaction and impaction groups were studied, and the variables were analyzed with multivariate discriminatory analysis. Significant differences between the two groups were found; variables describing spaces between the anterior of the ramus and the distal of the mandibular second molar and tooth size appeared to be the primary contributors to the differences observed.

[Tissue engineered bone scaffold material in restoration of alveolar socket after extraction of lower impacted third molar].

PubMed

Chen, Zhi-fang

2011-02-01

To investigate the effects of tissue engineered bone scaffold material in the restoration of alveolar socket after extraction of lower impacted third molar. Thirteen patients were immediately implanted with Bio-oss or PerioGlas® in the alveolar cavity after impacted mandibular third molar extraction. Clinical observation and X-ray were taken 1 to 12 weeks after operation. Paired t test was used for statistical analysis by SPSS10.0 software package. Thirteen patients did not experience postoperative complications. The distal alveolar height of the second molar and the gingival attachment did decrease significantly 1 to 12 weeks after operation(P < 0.05). Tissue engineered bone scaffold material is helpful in the restoration of alveolar socket after impacted third molar extraction.

Fixed versus Removable Appliance for Palatal Expansion; A 3D Analysis Using the Finite Element Method

PubMed Central

Geramy, Allahyar; Shahroudi, Atefe Saffar

2014-01-01

Objective: Several appliances have been used for palatal expansion for treatment of posterior cross bite. The purpose of this study was to evaluate the stress induced in the apical and crestal alveolar bone and the pattern of tooth displacement following expansion via removable expansion plates or fixed-banded palatal expander using the finite element method (FEM) analysis. Materials and Methods: Two 3D FEM models were designed from a mesio-distal slice of the maxilla containing the upper first molars, their periodontium and alveolar bone. Two palatal expanders (removable and fixed) were modeled. The models were designed in SolidWorks 2006 and then transferred to ANSYS Workbench. The appliance halves were displaced 0.1 mm laterally. The von Mises stress in the apical, crestal, and PDL areas and also the vertical displacement of the cusps (palatal and buccal) was were evaluated. Results: The total PDL stress was 0.40003 MPa in the removable appliance (RA) model and 4.88e-2 MPa in the fixed appliance (FA) model and the apical stress was 9.9e-2 and 1.17e-2 MPa, respectively. The crestal stress was 2.99e-1 MPa in RA and 7.62e-2 MPa in the FA. The stress in the cortical bone crest was 0.30327 and 7.9244e-2 MPa for RA and FA, respectively and 3.7271 and 7.4373e-2 MPa in crestal area of spongy bone, respectively. The vertical displacement of the buccal cusp and palatal cusp was 1.64e-2 and 5.90e-2 mm in RA and 1.05e-4 and 1.7e-4 mm in FA, respectively. Conclusion: The overall stress as well as apical and crestal stress in periodontium of anchor teeth was higher in RA than FA; RA elicited higher stress in both cortical and spongy bone. The vertical displacement of molar cusps was more in removable than fixed palatal expander model. PMID:24910679

Three-dimensional finite element analysis of vertical and angular misfit in implant-supported fixed prostheses.

PubMed

Assunção, Wirley Gonçalves; Gomes, Erica Alves; Rocha, Eduardo Passos; Delben, Juliana Aparecida

2011-01-01

Three-dimensional finite element analysis was used to evaluate the effect of vertical and angular misfit in three-piece implant-supported screw-retained fixed prostheses on the biomechanical response in the peri-implant bone, implants, and prosthetic components. Four three-dimensional models were fabricated to represent a right posterior mandibular section with one implant in the region of the second premolar (2PM) and another in the region of the second molar (2M). The implants were splinted by a three-piece implant-supported metal-ceramic prosthesis and differed according to the type of misfit, as represented by four different models: Control = prosthesis with complete fit to the implants; UAM (unilateral angular misfit) = prosthesis presenting unilateral angular misfit of 100 μm in the mesial region of the 2M; UVM (unilateral vertical misfit) = prosthesis presenting unilateral vertical misfit of 100 μm in the mesial region of the 2M; and TVM (total vertical misfit) = prosthesis presenting total vertical misfit of 100 μm in the platform of the framework in the 2M. A vertical load of 400 N was distributed and applied on 12 centric points by the software Ansys, ie, a vertical load of 150 N was applied to each molar in the prosthesis and a vertical load of 100 N was applied at the 2PM. The stress values and distribution in peri-implant bone tissue were similar for all groups. The models with misfit exhibited different distribution patterns and increased stress magnitude in comparison to the control. The highest stress values in group UAM were observed in the implant body and retention screw. The groups UVM and TVM exhibited high stress values in the platform of the framework and the implant hexagon, respectively. The three types of misfit influenced the magnitude and distribution of stresses. The influence of misfit on peri-implant bone tissue was modest. Each type of misfit increased the stress values in different regions of the system.

[Finite element analysis of mechanical characteristics during retracting mandibular incisors through sliding mechanics].

PubMed

Gu, Yong-Jia; Wu, Yan-Ping; Gao, Mei-Qin; Yao, Ning; Chen, Wen-Jing

2008-10-01

To analyze the mechanical characteristic changes of teeth and arch under different loading direction during retracting mandibular incisors through implant, simulating clinical loading system. Three- dimensional finite element model, including brackets, archwire, crampable hooks and implants, was reconstructed. The force direction was determined by connecting the points in crampable hook and the center point of implant, and the force point and force direction were changed with the adjustment of the height of crampable hook and the height of implant. Then three-dimensional movement trend of teeth, stress distribution in periodontal membrane and the largest displacement of archwire nodes in each group were calculated and analyzed. SPSS13.0 software package was used for statistical analysis. It was found that the height of implant and the height of crampable hook were correlated with the movement of teeth and stress distribution in periodontal membrane (P<0.01). The movement trend of teeth in the condition of different height of implant and different height of crampable hook was illustrated as follows:(1)with the height increase of crampable hook, the movement trend of the central and lateral incisors varied from mesial lingual tipping to mesial labial tipping. However, canines tipped distally and lingually; the second premolars tipped mesially and lingually, and the first molar roots tipped distally and buccally with decreasing tipping angle. (2) The largest stress distribution in the whole arch was located in the labial apical one-third area of the lateral incisors, while that of canines and the first molars was located in the alveolar ridges and root bifurcations. These findings indicate that the different movement trend during retracting anterior teeth can be achieved through the adjustment of the height of crampable hook, and implant, anchorage can effectively control anterior movement of the posterior teeth. Supported by Research Fund of Bureau of Science and Technology of Nantong City (Grant No. S40023).

Third Molar and Their Relationship with Caries on the Distal Surface of Second Molar: A Meta-analysis.

PubMed

Glória, José Cristiano Ramos; Martins, Carolina Castro; Armond, Anna Catharina Vieira; Galvão, Endi Lanza; Dos Santos, Cássio Roberto Rocha; Falci, Saulo Gabriel Moreira

2018-06-01

The aim of this meta-analysis was to determine which characteristics of mandibular third molars (MTMs) are more often associated with an increase in the prevalence/incidence of caries on the distal surface of mandibular second molars (MSMs). Three electronic databases were analyzed: PubMed; OVID and the Virtual Health Library. Observational studies were included, and the risk of bias was assessed using The Newcastle-Ottawa Scale. The Comprehensive Meta-Analysis software program was used for meta-analysis. Fifteen studies were included in this systematic review, and five were included in the meta-analysis. The distal surface of MSMs were more likely to exhibit caries in the following scenarios: when MTMs were found in the A position, rather than the C position (OR: 3.45, 95% CI: 2.28-5.22, p<0.001); when the horizontal position was compared with the vertical (OR: 8.12, 95% CI: 3.75-17.58, p<0.001) and distoangular (OR: 9.75, 95% CI: 3.49 - 27.25, p<0.001) positions; and when the mesioangular position was compared with the vertical (OR: 7.25, 95% CI: 3.48-15.10, p<0.001) and distoangular (OR: 9.54, 95% CI: 3.47 - 26.21, p<0.001) positions. The results of this study suggest that the presence of MTMs increases the incidence of caries on the distal surface of MSMs. Furthermore, caries on the distal surface of MSMs is more commonly associated with position A and horizontal and mesioangular mandibular molars.

Topographic analysis of maxillary premolars and molars and maxillary sinus using cone beam computed tomography.

PubMed

Yoshimine, Shin-Ichiro; Nishihara, Kazuhide; Nozoe, Etsuro; Yoshimine, Masako; Nakamura, Norifumi

2012-12-01

This study evaluated the anatomical characteristics of the maxillary premolars and molars and the maxillary sinus using cone beam computed tomography (CBCT) for dental implant treatment. Ten linear items and 1 angular item on 30 sites in 30 patients were measured on 3-dimensional computed tomography images using CBCT. The vertical relationship between the maxillary sinus and the maxillary molars was classified into 5 categories. The horizontal thickness of the buccal alveolar bone was thinnest on the maxillary first premolars, and the horizontal thickness of the palatal alveolar bone was thickest on the maxillary second molars. Type II was most common on the maxillary first molars. The internal angle at the maxillary premolars was significantly greater than that at the maxillary molars. The internal angle and vertical distance between the apex of the roots and the maxillary sinus floor showed a positive correlation on the maxillary first premolars (P = 0.003). For the selection of an appropriate approach on dental implant treatment, the evaluation of maxillary premolars and molars using of CBCT can be recommended.

Are hypomineralised lesions on second primary molars (HSPM) a predictive sign of molar incisor hypomineralisation (MIH)? A systematic review and a meta-analysis.

PubMed

Garot, Elsa; Denis, Alice; Delbos, Yves; Manton, David; Silva, Mihiri; Rouas, Patrick

2018-05-01

Molar Incisor Hypomineralisation (MIH) and Hypomineralised Second Primary Molars (HSPM) involve qualitative structural developmental anomalies of tooth enamel affecting the first permanent molars (and often incisors) and the second primary molars, respectively. A putative relationship between HSPM and MIH has been reported in the scientific literature. The aim was to determine whether children with HSPM are more likely to develop MIH. A systematic search using PubMed/Medline, Embase and Cochrane Library electronic databases for publications from 2001 to August 2017 investigating the link between MIH and HSPM was undertaken. Four reviewers selected the studies independently, extracted the data according to PRISMA statement, and assessed the bias risk with the Newcastle-Ottawa Scale (NOS) criteria. From 645 potentially eligible studies, 14 were selected for full text analysis and 5 were included in the meta-analysis. Cross-sectional and cohort studies were reported and 4662 participants were included. The meta-analyses were performed with a random model calculated an OR total of 4.66 (95% CI 2.11-10.26; P < 0.001). The weighted mean of the co-occurrence of HSPM and MIH prevalence was 19.94%. The high heterogeneity (I 2  = 88%) can be explained by the great variation present in number of participants and variable caries risk. Despite the limitations of the study, the presence of HSPM is predictive for MIH, with greater MIH prevalence in the presence of mild HSPM. Early detection and preventive intervention could reduce MIH complications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Morphometric analysis of developing crowns of maxillary primary second molars and permanent first molars in humans.

PubMed

Peretz, B; Nevis, N; Smith, P

1998-07-01

The purpose of this study was firstly to characterize the changes occurring in size and form of the mineralizing maxillary second primary molar and first permanent molar crowns, and secondly to determine if similar changes in size and form characterize enamel apposition in the crowns of these teeth. Twenty-five primary second molars and 20 maxillary permanent first molars at various stages of development, found in archaeological excavations in Israel, were examined for a number of measured variables using image analyser software. Teeth were divided into two groups according to their stage of development: stage I included all teeth at an early stage of development in which mesiobuccal-cusp height was less than 5 mm for the primary molar and 5.9 mm for the permanent molar; stage 2 included all teeth in later stages of development where mesiobuccal-cusp height was greater than these values. In the primary molar, a significant increase was found between the two stages in almost all variables. Significant correlations were also found between all intercusp distances and the external variables. Strong correlations between height of the mesiobuccal cusp and all external and internal variables were noted in stage 1, but fewer in stage 2. In the permanent tooth, no increase was observed in intercusp distances and very few correlations were found between and among the variables. The results suggest that a change in the shape of the maxillary primary second molar occurs during formation, with the lingual cusp tips moving lingually and distally, and the distobuccal cusp tips moving distally. No change occurs in the shape of the maxillary permanent first molar during crown formation. Growth of the maxillary primary second and permanent first molar crowns occurs in 'bursts' of development.

The in vitro effect of fluoridated milk in a bacterial biofilm--enamel model.

PubMed

Arnold, Wolfgang H; Forer, Stefan; Heesen, Joerg; Yudovich, Keren; Steinberg, Doron; Gaengler, Peter

2006-07-01

The purpose of this study was to investigate the effect of milk and fluoridated milk on bacterially induced caries-like lesions. Extracted impacted human molars were cut in half and covered with a varnish leaving a 4*4 mm window. The samples were coated with biofilm of S. sobrinus and were further divided into three experimental groups of S. sobrinus, S. sobrinus and milk and S. sobrinus and fluoridated milk. As negative controls served teeth incubated in saline. Of twenty tooth halves serial ground sections were cut through the lesions and investigated with polarization light microscopy (PLM) and scanning electron microscopy (SEM) and EDX element analysis. The PLM photographs were used for 3D reconstruction, volumetric assessment and determination of the extension of the lesion zones. Of eight tooth halves the biofilm on the enamel surface was studied with SEM and EDX element analysis. Volumetric assessment showed a statistically significant difference in the volume of the body of the lesion and the translucent zone between the milk group and fluoridated milk group. Quantitative element analysis demonstrated significant differences between sound enamel and the superficial layer in the fluoridated milk group. The biofilm on the enamel surface showed an increased Ca content in the milk group and fluoridated milk group. Milk as a common nutrient seems to play a complex role in in-vitro biofilm--enamel interactions stimulating bacterial demineralization on one hand, and, as effective fluoride carrier, inhibits caries-like demineralization.

Present and future in the use of micro-CT scanner 3D analysis for the study of dental and root canal morphology.

PubMed

Grande, Nicola M; Plotino, Gianluca; Gambarini, Gianluca; Testarelli, Luca; D'Ambrosio, Ferdinando; Pecci, Raffaella; Bedini, Rossella

2012-01-01

The goal of the present article is to illustrate and analyze the applications and the potential of microcomputed tomography (micro-CT) in the analysis of tooth anatomy and root canal morphology. The authors performed a micro-CT analysis of the following different teeth: maxillary first molars with a second canal in the mesiobuccal (MB) root, mandibular first molars with complex anatomy in the mesial root, premolars with single and double roots and with complicated apical anatomy. The hardware device used in this study was a desktop X-ray microfocus CT scanner (SkyScan 1072, SkyScan bvba, Aartselaar, Belgium). A specific software ResolveRT Amira (Visage Imaging) was used for the 3D analysis and imaging. The authors obtained three-dimensional images from 15 teeth. It was possible to precisely visualize and analyze external and internal anatomy of teeth, showing the finest details. Among the 5 upper molars analyzed, in three cases, the MB canals joined into one canal, while in the other two molars the two mesial canals were separate. Among the lower molars two of the five samples exhibited a single canal in the mesial root, which had a broad, flat appearance in a mesiodistal dimension. In the five premolar teeth, the canals were independent; however, the apical delta and ramifications of the root canals were quite complex. Micro-CT offers a simple and reproducible technique for 3D noninvasive assessment of the anatomy of root canal systems.

Three-dimensional analysis of third molar development to estimate age of majority.

PubMed

Márquez-Ruiz, Ana Belén; Treviño-Tijerina, María Concepción; González-Herrera, Lucas; Sánchez, Belén; González-Ramírez, Amanda Rocío; Valenzuela, Aurora

2017-09-01

Third molars are one of the few biological markers available for age estimation in undocumented juveniles close the legal age of majority, assuming an age of 18years as the most frequent legal demarcation between child and adult status. To obtain more accurate visualization and evaluation of third molar mineralization patterns from computed tomography images, a new software application, DentaVol©, was developed. Third molar mineralization according to qualitative (Demirjian's maturational stage) and quantitative parameters (third molar volume) of dental development was assessed in multi-slice helical computed tomography images of both maxillary arches displayed by DentaVol© from 135 individuals (62 females and 73 males) aged between 14 and 23years. Intra- and inter-observer agreement values were remarkably high for both evaluation procedures and for all third molars. A linear correlation between third molar mineralization and chronological age was found, with third molar maturity occurring earlier in males than in females. Assessment of dental development with both procedures, by using DentaVol© software, can be considered a good indicator of age of majority (18years or older) in all third molars. Our results indicated that virtual computed tomography imaging can be considered a valid alternative to orthopantomography for evaluations of third molar mineralization, and therefore a complementary tool for determining the age of majority. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Radiographic assessment of lower third molar eruption in different anteroposterior skeletal patterns and age-related groups.

PubMed

Jakovljevic, Aleksandar; Lazic, Emira; Soldatovic, Ivan; Nedeljkovic, Nenad; Andric, Miroslav

2015-07-01

To analyze radiographic predictors for lower third molar eruption among subjects with different anteroposterior skeletal relations and of different age groups. In total, 300 lower third molars were recorded on diagnostic digital orthopantomograms (DPTs) and lateral cephalograms (LCs). The radiographs were grouped according to sagittal intermaxillary angle (ANB), subject age, and level of lower third molar eruption. The DPT was used to analyze retromolar space, mesiodistal crown width, space/width ratio, third and second molar angulation (α, γ), third molar inclination (β), and gonion angle. The LC was used to determine ANB, angles of maxillar and mandibular prognathism (SNA, SNB), mandibular plane angle (SN/MP), and mandibular lengths. A logistic regression model was created using the statistically significant predictors. The logistic regression analysis revealed a statistically significant impact of β angle and distance between gonion and gnathion (Go-Gn) on the level of lower third molar eruption (P < .001 and P < .015, respectively). The retromolar space was significantly increased in the adult subgroup for all skeletal classes. The lower third molar impaction rate was significantly higher in the adult subgroup with the Class II (62.3%) compared with Class III subjects (31.7%; P < .013). The most favorable values of linear and angular predictors of mandibular third molar eruption were measured in Class III subjects. For valid estimation of mandibular third molar eruption, certain linear and angular measures (β angle, Go-Gn), as well as the size of the retromolar space, need to be considered.

Dendrochemical response to soil fertilization

Treesearch

David R. DeWalle; Jeffrey S. Tepp; Bryan R. Swistock; Pamela J. Edwards; William E. Sharpe; Mary Beth Adams; James N. Kochenderfer

2003-01-01

Use of chemical element content of tree rings to detect soil acid or base changes was tested at 13 sites of former forest fertilization trials in the eastern United States and Canada. Ammonium sulfate or nitrogen fertilization was the typical acidification treatment, while lime added with or without other fertilizer was the typical base treatment. Molar ratios of...

Opinions of American and Swedish orthodontists about the role of erupting third molars as a cause of dental crowding.

PubMed

Tüfekçi, E; Svensk, D; Kallunki, J; Huggare, J; Lindauer, S J; Laskin, D M

2009-11-01

To compare the opinions of Swedish orthodontists and American orthodontists regarding the association between third molar eruption and dental crowding. A survey was distributed to Swedish orthodontists (n = 230) asking their views on the force exerted by erupting third molars, its relationship to crowding, and their recommendations for prophylactic removal. Results were compared with those from a similar study conducted in the United States. Chi square analysis was used to determine differences in responses to questions between Swedish and American orthodontists. P < or = .05 was considered significant. Both Swedish and American orthodontists believed that lower third molars were more likely than upper third molars to cause force (65% and 58% for Swedish and American orthodontists, respectively) and crowding (42% and 40%, respectively). No statistically significant differences were seen between the answers of American and Swedish orthodontists regarding the role of upper and lower third molars in causing crowding. Although only 18% of Swedish orthodontists "generally" or "sometimes" recommended prophylactic removal of mandibular third molars, 36% of American orthodontists "generally" or "sometimes" recommended removal (P < .0001). Most orthodontists in the United States and Sweden do believe that erupting lower third molars exert an anterior force; however, they also believe that these teeth "rarely" or "never" cause crowding of the dentition. The reason that more American orthodontists recommend prophylactic removal of mandibular third molars remains unexplained.

[Study of the relationship between congenital missing of the third molar and the development of the mandibular angle].

PubMed

Chen, Yan-Na; Zheng, Bo-Wen; Liu, Yi

2017-02-01

Based on the research of the congenital missing of the third molar and the missing number, the relationship beteen congenital missing of the third molar and the development of the mandibular angle was evaluated. Patients were divided into experimental group and control group, the experimental group included 227 patients, each had at least one of the third molars congenital lost; 227 patients who had four third molar were selected as control group. Winceph software was used to measure the lateral cephalograms. SPSS17.0 software package was used to perform statistical analysis. Gonial angle, upper Gonial angle and lower Gonial angle between the experimental group and the control group showed significant difference and the values in the experimental group were significantly smaller than in the control group, but there was no gender difference between the two groups.There was no difference between Gonial angle, upper Gonial angle,lower Gonial angle and the missing number of the third molar. There is a close relationship between congenital missing third molar and Gonial angle, upper Gonial angle, lower Gonial angle, but there is no significant association with gender and the patients with congenital missing third molar have shorter craniofacial structure. Congenital missing number of the third molar has no significant association with Gonial angle, upper Gonial angle and lower Gonial angle.

Root canal morphology of primary molars: a micro-computed tomography study.

PubMed

Fumes, A C; Sousa-Neto, M D; Leoni, G B; Versiani, M A; da Silva, L A B; da Silva, R A B; Consolaro, A

2014-10-01

This was to investigate the root canal morphology of primary molar teeth using micro-computed tomography. Primary maxillary (n = 20) and mandibular (n = 20) molars were scanned at a resolution of 16.7 μm and analysed regarding the number, location, volume, area, structured model index (SMI), area, roundness, diameters, and length of canals, as well as the thickness of dentine in the apical third. Data were statistically compared by using paired-sample t test, independent sample t test, and one-way analysis of variance with significance level set as 5%. Overall, no statistical differences were found between the canals with respect to length, SMI, dentine thickness, area, roundness, and diameter (p > 0.05). A double canal system was observed in the mesial and mesio-buccal roots of the mandibular and maxillary molars, respectively. The thickness in the internal aspect of the roots was lower than in the external aspect. Cross-sectional evaluation of the roots in the apical third showed flat-shaped canals in the mandibular molars and ribbon- and oval-shaped canals in the maxillary molars. External and internal anatomy of the primary first molars closely resemble the primary second molars. The reported data may help clinicians to obtain a thorough understanding of the morphological variations of root canals in primary molars to overcome problems related to shaping and cleaning procedures, allowing appropriate management strategies for root canal treatment.

Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study

PubMed Central

Mah, Su-Jung; Kim, Ji-Eun; Ahn, Eun Jin; Nam, Jong-Hyun; Kim, Ji-Young

2016-01-01

Skeletal anchorage-assisted upper molar distalization has become one of the standard treatment modalities for the correction of Class II malocclusion. The purpose of this study was to analyze maxillary molar movement patterns according to appliance design, with the simultaneous use of buccal fixed orthodontic appliances. The authors devised two distinct types of midpalatal miniscrew-assisted maxillary molar distalizers, a lingual arch type and a pendulum type. Fourteen patients treated with one of the two types of distalizers were enrolled in the study, and the patterns of tooth movement associated with each type were compared. Pre- and post-treatment lateral cephalograms were analyzed. The lingual arch type was associated with relatively bodily upper molar distalization, while the pendulum type was associated with distal tipping with intrusion of the upper molar. Clinicians should be aware of the expected tooth movement associated with each appliance design. Further well designed studies with larger sample sizes are required. PMID:26877983

Cervical vertebral and dental maturity in Turkish subjects.

PubMed

Başaran, Güvenç; Ozer, Törün; Hamamci, Nihal

2007-04-01

The aim of this study was to investigate the relationships between the stages of calcification of teeth and the cervical vertebral maturity stages in Turkish subjects. A retrospective cross-sectional study was designed. The final study population consisted of 590 Turkish subjects. Statistical analysis of the data was performed with computer software. Spearman rank order correlation coefficients were used to assess the relationship between cervical vertebral and dental maturation. For a better understanding of the relationship between cervical vertebral maturation indexes and dental age, percentage distributions of the studied teeth were also calculated. Strict correlations were found between dental and cervical vertebral maturation of Turkish subjects. For males, the sequence from lowest to the highest was third molar, central incisor, canine, first premolar, second premolar, first molar, and second molar. For females, the sequence from lowest to the highest was third molar, canine, second premolar, first premolar, central incisor, first molar, and second molar. Dental maturation stages can be used as a reliable indicator of facial growth.

Continuous production of lipase-catalyzed biodiesel in a packed-bed reactor: optimization and enzyme reuse study.

PubMed

Chen, Hsiao-Ching; Ju, Hen-Yi; Wu, Tsung-Ta; Liu, Yung-Chuan; Lee, Chih-Chen; Chang, Cheng; Chung, Yi-Lin; Shieh, Chwen-Jen

2011-01-01

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

Association between third molar and mandibular angle fracture: A systematic review and meta-analysis.

PubMed

Giovacchini, Francesco; Paradiso, Daniele; Bensi, Caterina; Belli, Stefano; Lomurno, Giuseppe; Tullio, Antonio

2018-04-01

The aim of this study was to investigate the risk of mandibular angle fracture associated with the presence of a mandibular third molar and its position when the mandibular fracture occurs. A systematic literary search was performed in Pubmed, Scopus, and the Cochrane Library for observational studies with at least 250 patients that included frequency of mandibular angle fracture, presence of third molar, and its position. A total of seven studies were included in the review, from an initial search of 622 titles. The relative risk of mandibular angle fracture with third molar was 1.90 (95% CI = 1.47-2.46). The relative risk of mandibular angle fracture related to third molar position (according to the Pell and Gregory classification) was 1.18 (95% CI = 0.62-2.25), 1.98 (95% CI = 0.95-4.10), 2.72 (95% CI = 1.78-4.16), 1.31 (95% CI = 0.80-2.14), 2.21 (95% CI = 1.69-2.87) and 2.99 (95% CI = 2.12-4.22) for Class A, Class B, Class C, Class I, Class II, and Class III, respectively. Our meta-analysis reported a two-fold increased risk of mandibular angle fracture with the presence of a third molar in patients who presented with mandibular fractures. Even the third molar position seemed to influence mandibular angle fracture, especially Class C, Class II, and Class III. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Middle mesial canals in mandibular molars: incidence and related factors.

PubMed

Nosrat, Ali; Deschenes, Raney J; Tordik, Patricia A; Hicks, M Lamar; Fouad, Ashraf F

2015-01-01

Although the internal anatomy of mandibular molars has been extensively studied, information about middle mesial (MM) canals is limited. The primary aim of this retrospective study was to evaluate the incidence of MM canals in mandibular first and second molars. The secondary aim was to correlate the incidence of MM canals with variables of molar type, sex, age, ethnicity, and presence of a second distal canal. All mature permanent first and second mandibular molars treated from August 2012 to May 2014 were included in the analysis. After completion of root canal instrumentation in all main canals, the clinician inspected the isthmus area of the mesial root using the dental operating microscope. If there was a catch point in this area with a file or explorer, the operator spent more time attempting to negotiate an MM canal. Seventy-five mandibular first and second molars were treated during the specified period. Fifteen (20%) teeth had negotiable MM canals. The incidence of MM canals was 32.1% in patients ≤ 20 years old, 23.8% in patients 21-40 years old, and 3.8% in patients > 40 years. Analysis of data revealed a significant difference in the distribution of MM canals among different age groups (P < .05). The differences in the distribution of MM canals based on sex, ethnicity, molar type, and presence of a second distal canal were not significant. The incidence of negotiable MM canals overall and their frequency of identification in younger patients were higher than in previous reports. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Prosthodontic decision-making relating to dentitions with compromised molars: the perspective of Swedish General Dental Practitioners.

PubMed

Korduner, E-K; Collin Bagewitz, I; Vult von Steyern, P; Wolf, E

2016-12-01

The aim of this investigation was to study the clinical prosthodontic decision-making process relating to dentitions with compromised molars among Swedish general dental practitioners (GDPs). Eleven Swedish GDPs were purposively selected, and all agreed to participate. Then, in-depth, semi-structured interviews were conducted and covered treatment considerations concerning two authentic patient cases, initially with complete dental arches, and later, a final treatment based on a shortened dental arch (SDA) was discussed. The cases involved patients with compromised teeth situated mainly in the molar regions. One patient suffered from extensive caries and the other from severe periodontal disease. Qualitative content analysis was used to analyse the data. In the systematic analysis, two main categories were identified: holistic and functional approach. Among the interviewed GDPs, focus was put on patients' needs, background history and motivation for treatment as well as the preservation of molar support. Within the limitations of this study, the following can be concluded: keeping a dental arch with molars seems to be important to Swedish general dental practitioners. The SDA concept does not seem to have a substantial impact on the prosthodontic decision-making relating to dentitions with compromised molars. The dentist's experiences, as well as colleagues' or consulting specialist advice together with aetiological factors and the patient's individual situation, influence the decision-making more than the SDA concept. The conflicting results in the prosthetic decision-making process concerning the relevance of age and the need for molar support need further investigation, for example based on decisions made in the dentist's own clinical practice. © 2016 John Wiley & Sons Ltd.

Piezoelectric Versus Conventional Rotary Techniques for Impacted Third Molar Extraction: A Meta-analysis of Randomized Controlled Trials.

PubMed

Jiang, Qian; Qiu, Yating; Yang, Chi; Yang, Jingyun; Chen, Minjie; Zhang, Zhiyuan

2015-10-01

Impacted third molars are frequently encountered in clinical work. Surgical removal of impacted third molars is often required to prevent clinical symptoms. Traditional rotary cutting instruments are potentially injurious, and piezosurgery, as a new osteotomy technique, has been introduced in oral and maxillofacial surgery. No consistent conclusion has been reached regarding whether this new technique is associated with fewer or less severe postoperative sequelae after third molar extraction.The aim of this study was to compare piezosurgery with rotary osteotomy techniques, with regard to surgery time and the severity of postoperative sequelae, including pain, swelling, and trismus.We conducted a systematic literature search in the Cochrane Library, PubMed, Embase, and Google Scholar.The eligibility criteria of this study included the following: the patients were clearly diagnosed as having impacted mandibular third molars; the patients underwent piezosurgery osteotomy, and in the control group rotary osteotomy techniques, for removing impacted third molars; the outcomes of interest include surgery time, trismus, swelling or pain; the studies are randomized controlled trials.We used random-effects models to calculate the difference in the outcomes, and the corresponding 95% confidence interval. We calculated the weighted mean difference if the trials used the same measurement, and a standardized mean difference if otherwise.A total of seven studies met the eligibility criteria and were included in our analysis. Compared with rotary osteotomy, patients undergoing piezosurgery experienced longer surgery time (mean difference 4.13 minutes, 95% confidence interval 2.75-5.52, P < 0.0001). Patients receiving the piezoelectric technique had less swelling at postoperative days 1, 3, 5, and 7 (all Ps ≤0.023). Additionally, there was a trend of less postoperative pain and trismus in the piezosurgery groups.The number of included randomized controlled trials and the sample size of each trial were relatively small, double blinding was not possible, and cost analysis was unavailable due to a lack of data.Our meta-analysis indicates that although patients undergoing piezosurgery experienced longer surgery time, they had less postoperative swelling, indicating that piezosurgery is a promising alternative technique for extraction of impacted third molars.

Evaluation of stress distribution of implant-retained mandibular overdenture with different vertical restorative spaces: A finite element analysis

PubMed Central

Ebadian, Behnaz; Farzin, Mahmoud; Talebi, Saeid; Khodaeian, Niloufar

2012-01-01

Background: Available restorative space and bar height is an important factor in stress distribution of implant-supported overdentures. The purpose of this study was to evaluate the effect of different vertical restorative spaces and different bar heights on the stress distribution around implants by 3D finite element analysis. Materials and Methods: 3D finite element models were developed from mandibular overdentures with two implants in the interforaminal region. In these models, four different bar heights from gingival crest (0.5, 1, 1.5, 2 mm) with 15 mm occlusal plane height and three different occlusal plane heights from gingival crest (9, 12, 15 mm) with 2 mm bar height were analyzed. A vertical unilateral and a bilateral load of 150 N were applied to the central occlusal fossa of the first molar and the stress of bone around implant was analyzed by finite element analysis. Results: By increasing vertical restorative space, the maximum stress values around implants were found to be decreased in unilateral loading models but slightly increased in bilateral loading cases. By increasing bar height from gingival crest, the maximum stress values around implants were found to be increased in unilateral loading models but slightly decreased in bilateral loading cases. In unilateral loading models, maximum stress was found in a model with 9 mm occlusal plane height and 1.5 mm bar height (6.254 MPa), but in bilateral loading cases, maximum stress was found in a model with 15 mm occlusal plane height and 0.5 mm bar height (3.482 MPa). Conclusion: The reduction of bar height and increase in the thickness of acrylic resin base in implant-supported overdentures are biomechanically favorable and may result in less stress in periimplant bone. PMID:23559952

Panoramic radiographic predictors of mandibular third molar eruption.

PubMed

Niedzielska, Iwona Anna; Drugacz, Jan; Kus, Nina; Kreska, Joanna

2006-08-01

Third molar (M3) eruption can be problematic. According to some orthodontic surgeons, the teeth are capable of aggravating the average crowding level in the dental arch. The question is whether it might be possible to give a prognosis for ultimate M3 position in the arch and make an early decision to extract or retain them. The purpose of the study was to determine which measurements made on panoramic tomograms might facilitate prognosis for M3 position in the dental arch over the years. The investigation involved 64 patients who had been enrolled to the study group 10 years earlier, ie, in 1993, when an analysis had been carried out regarding M3 effect on dental arch crowding. At that time panoramic tomograms had been taken, and dental casts made. The procedures were repeated in 2003. The following measurements were taken at baseline (1993) and at the end of the study (2003): (1)/the retromolar space to lower third molar crown width, (2) third molar angulation to the base of the mandible, and (3) third molar to second molar inclination. At some defined values of the Ganss ratio, and M3 inclination to mandibular base and second molar, it is possible to predict potential lower third molar alignment in the dental arch using a panoramic radiograph.

Design of copper DNA intercalators with leishmanicidal activity.

PubMed

Navarro, Maribel; Cisneros-Fajardo, Efrén José; Sierralta, Aníbal; Fernández-Mestre, Mercedes; Silva, Pedro; Arrieche, Dwight; Marchán, Edgar

2003-04-01

The complexes [Cu(dppz)(NO(3))]NO(3) (1), [Cu(dppz)(2)(NO(3))]NO(3) (2), [Cu(dpq)(NO(3))]NO(3) (3), and [Cu(dpq)(2)(NO(3))]NO(3) (4) were synthesized and characterized by elemental analysis, FAB-mass spectrometry, EPR, UV, and IR spectroscopies, and molar conductivity. DNA interaction studies showed that intercalation is an important way of interacting with DNA for these complexes. The biological activity of these copper complexes was evaluated on Leishmania braziliensis promastigotes, and the results showed leishmanicidal activity. Preliminary ultrastructural studies with the most active complex (2) at 1 h revealed parasite swelling and binucleated cells. This finding suggests that the leishmanicidal activity of the copper complexes could be associated with their interaction with the parasitic DNA.

Preparation, Characterization, and Antimicrobial Activities of Bimetallic Complexes of Sarcosine with Zn(II) and Sn(IV)

PubMed Central

Arafat, Yasir; Ali, Saqib; Shahzadi, Saira; Shahid, Muhammad

2013-01-01

Heterobimetallic complexes of Zn(II) and Sn(IV) with sarcosine have been synthesized at room temperature under stirring conditions by the reaction of sarcosine and zinc acetate in 2 : 1 molar ratio followed by the stepwise addition of CS2 and organotin(IV) halides, where R = Me, n-Bu, and Ph. The complexes were characterized by elemental analysis, FT-IR and NMR (1H, 13C) spectroscopy. IR data showed that the ligand acts in a bidentate manner. NMR data revealed the four coordinate geometry in solution state. In vitro antimicrobial activities data showed that complexes (3) and (4) were effective against bacterial and fungal strains with few exceptions. PMID:24235910

Synthesis, spectral and thermal studies of the newly hydrogen bonded charge transfer complex of o-phenylenediamine with π acceptor picric acid

NASA Astrophysics Data System (ADS)

Khan, Ishaat M.; Ahmad, Afaq

2010-10-01

Newly proton or charge transfer complex [(OPDH) +(PA) -] was synthesized by the reaction of the donor, o-phenylenediamine (OPD) with acceptor, 2,4,6-trinitrophenol (PAH). The chemical reaction has occurred via strong hydrogen bonding followed by migration of proton from acceptor to donor. UV-vis, 1H NMR and FTIR spectra, in addition to the thermal and elemental analysis were used to confirm the proposed occurrence of the chemical reaction and to investigate the newly synthesized solid CT complex. The stoichiometry of the CT complex was found to be 1:1. The formation constant and molar extinction coefficient of the CT complex were evaluated by the Benesi-Hildebrand equation.

Dietary Inference from Upper and Lower Molar Morphology in Platyrrhine Primates

PubMed Central

Allen, Kari L.; Cooke, Siobhán B.; Gonzales, Lauren A.; Kay, Richard F.

2015-01-01

The correlation between diet and dental topography is of importance to paleontologists seeking to diagnose ecological adaptations in extinct taxa. Although the subject is well represented in the literature, few studies directly compare methods or evaluate dietary signals conveyed by both upper and lower molars. Here, we address this gap in our knowledge by comparing the efficacy of three measures of functional morphology for classifying an ecologically diverse sample of thirteen medium- to large-bodied platyrrhines by diet category (e.g., folivore, frugivore, hard object feeder). We used Shearing Quotient (SQ), an index derived from linear measurements of molar cutting edges and two indices of crown surface topography, Occlusal Relief (OR) and Relief Index (RFI). Using SQ, OR, and RFI, individuals were then classified by dietary category using Discriminate Function Analysis. Both upper and lower molar variables produce high classification rates in assigning individuals to diet categories, but lower molars are consistently more successful. SQs yield the highest classification rates. RFI and OR generally perform above chance. Upper molar RFI has a success rate below the level of chance. Adding molar length enhances the discriminatory power for all variables. We conclude that upper molar SQs are useful for dietary reconstruction, especially when combined with body size information. Additionally, we find that among our sample of platyrrhines, SQ remains the strongest predictor of diet, while RFI is less useful at signaling dietary differences in absence of body size information. The study demonstrates new ways for inferring the diets of extinct platyrrhine primates when both upper and lower molars are available, or, for taxa known only from upper molars. The techniques are useful in reconstructing diet in stem representatives of anthropoid clade, who share key aspects of molar morphology with extant platyrrhines. PMID:25738266

Aging of monolithic zirconia dental prostheses: Protocol for a 5-year prospective clinical study using ex vivo analyses.

PubMed

Koenig, Vinciane; Wulfman, Claudine P; Derbanne, Mathieu A; Dupont, Nathalie M; Le Goff, Stéphane O; Tang, Mie-Leng; Seidel, Laurence; Dewael, Thibaut Y; Vanheusden, Alain J; Mainjot, Amélie K

2016-12-15

Recent introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) monolithic zirconia dental prostheses raises the issue of material low thermal degradation (LTD), a well-known problem with zirconia hip prostheses. This phenomenon could be accentuated by masticatory mechanical stress. Until now zirconia LTD process has only been studied in vitro . This work introduces an original protocol to evaluate LTD process of monolithic zirconia prostheses in the oral environment and to study their general clinical behavior, notably in terms of wear. 101 posterior monolithic zirconia tooth elements (molars and premolars) are included in a 5-year prospective clinical trial. On each element, several areas between 1 and 2 mm 2 (6 on molars, 4 on premolars) are determined on restoration surface: areas submitted or non-submitted to mastication mechanical stress, glazed or non-glazed. Before prosthesis placement, ex vivo analyses regarding LTD and wear are performed using Raman spectroscopy, SEM imagery and 3D laser profilometry. After placement, restorations are clinically evaluated following criteria of the World Dental Federation (FDI), complemented by the analysis of fracture clinical risk factors. Two independent examiners perform the evaluations. Clinical evaluation and ex vivo analyses are carried out after 6 months and then each year for up to 5 years. For clinicians and patients, the results of this trial will justify the use of monolithic zirconia restorations in dental practice. For researchers, the originality of a clinical study including ex vivo analyses of material aging will provide important data regarding zirconia properties.Trial registration: ClinicalTrials.gov Identifier: NCT02150226.

Synthesis, spectral and theoretical studies of Ni(II), Pd(II) and Pt(II) complexes of 5-mercapto-1,2,4-triazole-3-imine-2‧-hydroxynaphyhaline

NASA Astrophysics Data System (ADS)

Gaber, Mohamed; El-Ghamry, Hoda; Atlam, Faten; Fathalla, Shaimaa

2015-02-01

Ni(II), Pd(II) and Pt(II) complexes of 5-mercapto-1,2,4-triazole-3-imine-2‧-hydroxynaphthaline have been isolated and characterized by elemental analysis, IR, 1H NMR, EI-mass, UV-vis, molar conductance, magnetic moment measurements and thermogravimetric analysis. The molar conductance values indicated that the complexes are non-electrolytes. The magnetic moment values of the complexes displayed diamagnetic behavior for Pd(II) and Pt(II) complexes and tetrahedral geometrical structure for Ni(II) complex. From the bioinorganic applications point of view, the interaction of the ligand and its metal complexes with CT-DNA was investigated using absorption and viscosity titration techniques. The Schiff-base ligand and its metal complexes have also been screened for their antimicrobial and antitumor activities. Also, theoretical investigation of molecular and electronic structures of the studied ligand and its metal complexes has been carried out. Molecular orbital calculations were performed using DFT (density functional theory) at B3LYP level with standard 6-31G(d,p) and LANL2DZ basis sets to access reliable results to the experimental values. The calculations were performed to obtain the optimized molecular geometry, charge density distribution, extent of distortion from regular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), Mulliken atomic charges, reactivity index (ΔE), dipole moment (D), global hardness (η), softness (σ), electrophilicity index (ω), chemical potential and Mulliken electronegativity (χ).

Internal and external morphology of mandibular molars: An original micro-CT study and meta-analysis with review of implications for endodontic therapy.

PubMed

Tomaszewska, Iwona M; Skinningsrud, Bendik; Jarzębska, Anna; Pękala, Jakub R; Tarasiuk, Jacek; Iwanaga, Joe

2018-03-25

The aim of this radiological micro-CT study and meta-analysis was to determine the morphological features of the root canal anatomy of the mandibular molars. The radiological study included micro-CT scans of 108 mandibular first, 120 mandibular second, and 146 mandibular third molars. For our meta-analysis, an extensive search was conducted through PubMed, Embase, and Web of Science to identify articles eligible for inclusion. Data extracted included investigative method (cadaveric, intraoperative, or imaging), Vertucci type of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and intercanal communications. In the mesial roots of mandibular molars, the most frequent Vertucci type of canal configuration was type IV, except for the mandibular third molar where type I was most common. Type I was most common in the distal root. There were usually two canals in the mesial root and one in the distal root. Two was the most common number of roots, and a third root was most prevalent in Asia. One apical foramen was most common in the distal root and two apical foramina in the mesial root. Intercanal communications were most frequent in the mesial root. Knowledge of the complex anatomy of the mandibular molars can make root canal therapy more likely to succeed. We recommend the use of cone-beam computed tomography before and after endodontic treatment to enable the root anatomy to be accurately described and properly diagnosed, and treatment outcome to be assessed. Clin. Anat. 00:000-000, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Insulin-like growth factor-I (IGF-1), IGF-binding protein-3 (IGFBP-3) and mammographic features.

PubMed

Izzo, L; Meggiorini, M L; Nofroni, I; Pala, A; De Felice, C; Meloni, P; Simari, T; Izzo, S; Pugliese, F; Impara, L; Merlini, G; Di Cello, P; Cipolla, V; Forcione, A R; Paliotta, A; Domenici, L; Bolognese, A

2012-05-01

The IGF system has recently been shown to play an important role in the regulation of breast tumor cell proliferation. However, also breast density is currently considered as the strongest breast cancer risk factor. It is not yet clear whether these factors are interrelated and if and how they are influenced by menopausal status. The purpose of this study was to examine the possible effects of IGF-1 and IGFBP-3 and IGF-1/IGFBP-3 molar ratio on mammographic density stratified by menopausal status. A group of 341 Italian women were interviewed to collect the following data: family history of breast cancer, reproductive and menstrual factors, breast biopsies, previous administration of hormonal contraceptive therapy, hormone replacement therapy (HRT) in menopause and lifestyle information. A blood sample was drawn for determination of IGF-1, IGFBP-3 levels. IGF-1/ IGFBP-3 molar ratio was then calculated. On the basis of recent mammograms the women were divided into two groups: dense breast (DB) and non-dense breast (NDB). Student's t-test was employed to assess the association between breast density and plasma level of IGF-1, IGFBP-3 and molar ratio. To assess if this relationship was similar in subgroups of pre- and postmenopausal women, the study population was stratified by menopausal status and Student's t-test was performed. Finally, multivariate analysis was employed to evaluate if there were confounding factors that might influence the relationship between growth factors and breast density. The analysis of the relationship between mammographic density and plasma level of IGF-1, IGFBP-3 and IGF-1/ IGFBP-3 molar ratio showed that IGF-1 levels and molar ratio varied in the two groups resulting in higher mean values in the DB group (IGF-1: 109.6 versus 96.6 ng/ml; p= 0.001 and molar ratio 29.4 versus 25.5 ng/ml; p= 0.001) whereas IGFBP-3 showed similar values in both groups (DB and NDB). Analysis of plasma level of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio compared to breast density after stratification of the study population by menopausal status (premenopausal and postmenopausal) showed that there was no association between the plasma of growth factors and breast density, neither in premenopausal nor in postmenopausal patients. Multivariate analysis showed that only nulliparity, premenopausal status and body mass index (BMI) are determinants of breast density. Our study provides a strong evidence of a crude association between breast density and plasma levels of IGF-1 and molar ratio. On the basis of our results, it is reasonable to assume that the role of IGF-1 and molar ratio in the pathogenesis of breast cancer might be mediated through mammographic density. IGF-1 and molar ratio might thus increase the risk of cancer by increasing mammographic density.

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients.

PubMed

Mahasantipiya, Phattaranant May; Pramojanee, Sakarat; Thaiupathump, Trasapong

2013-12-01

This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. It might be possible to predict chronological age from the eruption height of the wisdom teeth.

Prevalence, association, and sexual dimorphism of Carabelli's molar and shovel incisor traits amongst Jordanian population.

PubMed

Khraisat, A; Taha, Sahar T; Jung, R E; Hattar, S; Smadi, L; Al-Omari, I K; Jarbawi, M

2007-09-01

The correlation between dental morphological traits can be used as an indicator to show major ethnic differences. Therefore, this study investigated the prevalence of Carabelli's molar and shovel incisor traits and tested their association and sexual dimorphism in Jordanian population. Three hundred subjects of school children at their 10th grade and of 15.5-year as an average age were involved. Alginate impressions for the maxillary arch were taken, poured, and casts were then trimmed. The selected accurate casts were of 132 male- and 155 female-students. The examined morphologic traits were Carabelli's trait on the maxillary first and second molars and shovel-shaped incisors. The relationship between different traits was investigated by Nonparametric Correlation analysis and Independent Sample t test was used to test sexual dimorphism in trait expression. The prevalence of Carabelli's trait in maxillary first molar and shovel trait in maxillary central incisor was relatively high (65.0 % and 53.0 %, respectively). The prevalence of Carabelli's trait on maxillary second molars was 3.8 %. Nonparametric Correlations revealed a strongest positive correlation between Carabelli's trait on maxillary first molar and shovel trait in males (P = 0.005). Significant sexual dimorphism was only found in the prevalence of Carabelli's trait on maxillary first molar (P = 0.013) and shovel trait (P = 0.038). The Jordanian Population had comparatively high prevalence of Carabelli's molar and shovel incisor traits. There was a positive association between Carabelli's trait on maxillary first molar and shovel trait in males. Sexual dimorphism was evident in Carabelli's trait on maxillary first molar and shovel trait.

Assessing the biodegradability of terrestrially-derived organic matter in Scottish sea loch sediments

NASA Astrophysics Data System (ADS)

Loh, P. S.; Miller, A. E. J.; Reeves, A. D.; Harvey, S. M.; Overnell, J.

2008-05-01

Lignin oxidation products, oxygen uptake rates, molar organic carbon to nitrogen (OC/N) ratio (from bulk elemental analysis) and Rp values (from loss on ignition experiments, the ratio of the refractory to total organic matter, OM) were determined for sediments along transects of Loch Creran and Loch Etive. Lignin data indicated the importance of riverine inputs contributing to land-derived carbon in the lochs as total lignin (Λ, mg/100 mg organic carbon, OC) decreased from 0.69 to 0.45 and 0.70 to 0.29 from the head to outside of Loch Creran and Loch Etive, respectively. In addition, significant correlations of lignin content against total OM and OC (p<0.05) also suggested a distinct contribution of terrestrial OM to carbon pools in the lochs. The general trend of decreasing oxygen uptake rates from the head (20.8 mmole m-2 day-1) to mouth (9.4 mmole m-2 day-1) of Loch Creran indicates decomposition of OM. Biodegradability of the sedimentary OM was also characterized by the increase of Rp values from the head to mouth of the lochs: 0.40 to 0.80 in Loch Etive and 0.43 to 0.63 in Loch Creran. Furthermore, the molar OC/N ratio decreased from 11.2 to 6.4 in Loch Creran, and from 17.5 to 8.2 in Loch Etive. Derived rate constants for OM degradation were found to decrease from LC0 to LC1, and increase from RE5 to RE6. This work demonstrates that oxygen uptake rates, Rp values and molar OC/N ratio are able to serve as useful proxies to indicate the biodegradability of sedimentary OM.

Prevalence of C-shaped canals in mandibular second and third molars in a central India population: A cone beam computed tomography analysis.

PubMed

Wadhwani, Shefali; Singh, Mahesh Pratap; Agarwal, Manish; Somasundaram, Pavithra; Rawtiya, Manjusha; Wadhwani, P K

2017-01-01

To evaluate the prevalence of C-shaped root canals in mandibular molars using cone beam computed tomography (CBCT) in a subpopulation of Central India. CBCT scans of patients from diagnostic imaging center were selected in accordance with the criteria given by Fan et al . (2004) for C-shaped canals. A total of 238 CBCT scans fulfilled the inclusion criteria and thereby divided into two groups: Group 1: Images showing C-shaped canal configuration in mandibular second molars. Group 2: Images showing C-shaped canal configuration in mandibular third molars. The frequency and distribution of canals and their configuration along with the position of lingual/buccal grooves in the images were evaluated, and the data was analyzed. CBCT evaluation showed that 9.7% of second molars and 8% of third molars had C-shaped canals. A prominent buccal groove was seen in these teeth. The data showed a significant difference ( P = 0.038) for the presence of such anatomy on the right side for mandibular third molars. The study showed a significant prevalence of C-shaped canal configuration in the subpopulation studied.

Prevalence of C-shaped canals in mandibular second and third molars in a central India population: A cone beam computed tomography analysis

PubMed Central

Wadhwani, Shefali; Singh, Mahesh Pratap; Agarwal, Manish; Somasundaram, Pavithra; Rawtiya, Manjusha; Wadhwani, P. K.

2017-01-01

Introduction: To evaluate the prevalence of C-shaped root canals in mandibular molars using cone beam computed tomography (CBCT) in a subpopulation of Central India. Materials and Methods: CBCT scans of patients from diagnostic imaging center were selected in accordance with the criteria given by Fan et al. (2004) for C-shaped canals. A total of 238 CBCT scans fulfilled the inclusion criteria and thereby divided into two groups: Group 1: Images showing C-shaped canal configuration in mandibular second molars. Group 2: Images showing C-shaped canal configuration in mandibular third molars. The frequency and distribution of canals and their configuration along with the position of lingual/buccal grooves in the images were evaluated, and the data was analyzed. Results: CBCT evaluation showed that 9.7% of second molars and 8% of third molars had C-shaped canals. A prominent buccal groove was seen in these teeth. The data showed a significant difference (P = 0.038) for the presence of such anatomy on the right side for mandibular third molars. Conclusion: The study showed a significant prevalence of C-shaped canal configuration in the subpopulation studied. PMID:29386785

Optimized synthesis of lipase-catalyzed hexyl acetate in n-hexane by response surface methodology.

PubMed

Shieh, C J; Chang, S W

2001-03-01

Hexyl acetate, a short-chain ester with fruity odor, is a significant green note flavor compound and widely used in the food industry. The ability for immobilized lipase from Mucor miehei (Lipozyme IM-77) to catalyze the transesterification of hexanol with triacetin was investigated in this study. Response surface methodology and five-level-five-factor central composite rotatable design were adopted to evaluate the effects of synthesis variables, such as reaction time (2-10 h), temperature (25-65 degrees C), enzyme amount (10-50%; 0.024-0.118 BAUN), substrate molar ratio of triacetin to hexanol (1:1 to 3:1), and added water content (0-20%) on percentage molar conversion of hexyl acetate. The results showed that reaction temperature and substrate molar ratio were the most important parameters and that added water content had less of an effect on percent molar conversion. On the basis of canonical analysis, optimum synthesis conditions were as follows: reaction time, 7.7 h; temperature, 52.6 degrees C; enzyme amount, 37.1% (0.089 BAUN); substrate molar ratio, 2.7:1; and added water, 12.5%. The predicted value was 88.9% molar conversion, and the actual experimental value was 86.6% molar conversion.

The effect of implant number and position on the stress behavior of mandibular implant retained overdentures: A three-dimensional finite element analysis.

PubMed

Topkaya, Tolga; Solmaz, Murat Yavuz

2015-07-16

The present study evaluated the effects of ball anchor abutment attached to implants with a 4.30 mm diameter and 11 mm insert length on stress distribution in a patient without any remaining teeth in the lower jaw. In the study, the stress analysis was performed for five different configurations (2 with 4 implant-supported and 3 with 2 implant-supported) and three different loading types using ANSYS Workbench software. The stresses measured in the 4 implant-supported models were lower compared to the stresses measured in the 2 implant-supported models. The stresses on the implants intensified on the cervical region of the implants. When the effects of the loading sites on the stress were examined, the loading on the first molar tooth produced the highest stresses on the implants. Copyright © 2015 Elsevier Ltd. All rights reserved.

[The effects of Ketac Molar Aplicap glass-ionomer material on growth of cariogenic bacteria contained in the dental plaque].

PubMed

Płuciennik-Stronias, Małgorzata; Sakowska, Danuta; Paul-Stalmaszczyk, Małgorzata; Bołtacz-Rzepkowska, Elzbieta

2012-01-01

In the aging population, the prevalence of root caries has been observed, which is a characteristic feature of the elderly people. The most important element used in caries prevention is fluoride, which is derived from the air, diet or fluoride-containing preparations and materials, e.g. glass-ionomer restorations. The aim of the study was to evaluate the effect of Ketac Molar Aplicap glass-ionomer on the growth of Lactobacillus sp. bacteria, one of the species most frequently found in the carietic focus of the tooth root. The study was carried out in 15 patients with good oral hygiene, in whom 35 fillings from Ketac Molar Aplicap conventional glass-ionomer material were performed. After 6 months, three-day dental plaque from these fillings and from the tooth enamel of the control group was examined. No statistically significant differences (p = 0.554) in the amounts of Lactobacillus sp. between the study and control group were revealed. Lack of inhibiting effect of glass-ionomer material on the growth of the dental plaque with Lactobacillus sp. after the time of observation is implied.

Characterizing property distributions of polymeric nanogels by size-exclusion chromatography.

PubMed

Mourey, Thomas H; Leon, Jeffrey W; Bennett, James R; Bryan, Trevor G; Slater, Lisa A; Balke, Stephen T

2007-03-30

Nanogels are highly branched, swellable polymer structures with average diameters between 1 and 100nm. Size-exclusion chromatography (SEC) fractionates materials in this size range, and it is commonly used to measure nanogel molar mass distributions. For many nanogel applications, it may be more important to calculate the particle size distribution from the SEC data than it is to calculate the molar mass distribution. Other useful nanogel property distributions include particle shape, area, and volume, as well as polymer volume fraction per particle. All can be obtained from multi-detector SEC data with proper calibration and data analysis methods. This work develops the basic equations for calculating several of these differential and cumulative property distributions and applies them to SEC data from the analysis of polymeric nanogels. The methods are analogous to those used to calculate the more familiar SEC molar mass distributions. Calibration methods and characteristics of the distributions are discussed, and the effects of detector noise and mismatched concentration and molar mass sensitive detector signals are examined.

Synthesis, Characterization and Antifertility Activity of New Unsymmetrical Macrocyclic Complexes of Tin(II)

PubMed Central

Sharma, Kripa; Joshi, S. C.

2000-01-01

A new series of unsymmetrical macrocyclic complexes of tin(ll) has been prepared by the template process using bis(3-oxo-2-butylidene)propane-1,3-diamine as precursor. This affords a method to synthesize these complexes with various ring sizes. The tetradentate macrocyclic precursor [N4mL] reacts with SnCl2 and different diamines in a 1:1:1 molar ratio in refluxing methanol to give complexes of the type [Sn(N4mL)Cl2]. The ring expansion has been achieved by varying the diamine between the two diacetyl amino nitrogen atoms. The macrocyclic precursor and its metal complexes have been characterized on the basis of elemental analysis, molar conductance, molecular weight determinations, IR, 1H NMR,13C NMR, 119Sn NMR and electronic spectral studies. An octahedral geometry around the metal ion is suggested for these complexes. On the basis of molecular weights and conductivity measurements, their monomeric and non-electrolytic nature has been confirmed. The precursor and complexes have been screened in vitro against a number of pathogenic fungi and bacteria to assess their growth inhibiting potential. The testicular sperm density and testicular sperm morphology, sperm motility, density of cauda epididymal spermatozoa and fertility in mating trails and biochemicals parameters of reproductive organs have been examined and discussed. PMID:18475951

Sensitivity differences between microporous NaY and hierarchical ZSM-5 modified electrodes as ammonia gas sensor

NASA Astrophysics Data System (ADS)

Lisnawati, E.; Agustin, I.; Krisnandi, Y. K.; Triyono, D.

2017-07-01

The hierarchical ZSM-5 had been successfully synthesized with double template using a hydrotermal method and microporous NaY zeolite had been successfully synthesized using a sol-gel method. XRD pattern confirmed hat the as-synthesized materials were ZSM-5 and NaY zeolites. SEM images of ZSM-5 showed that it has a hexagonal shape, which can be called coffin type,and rough surface. The EDS elemental analysis gives Si/Al molar ratio of 24.2. On the other hand, NaY crystals were intergrown in cuboid shapes with Si/Al molar ratio of 2. ZSM-5 and NaY were coated onto the surface of Interdigitated Capacitor (IDC) pattern made of gold/silver/quartz through spin coating method. IDC, ZSM-5/IDC and NaY/IDC were tested using Electrochemical Impedance Spectroscopy (EIS) method. The composite has different sensitivity in range concentration of ammonia 20-300 ppm. IDC has no significant effect of the presence of various concentrations, NaY/IDC and ZSM-5/IDC composite have frequency 100 Hz with R2 = 0.8312 and R2 = 0.8037. The NaY/IDC has higher sensitivity compared toZSM-5/IDC, this could be caused by the higher polarity of NaY compared to ZSM-5 to attract ammonia.

Synthesis, spectroscopic, anticancer, antibacterial and antifungal studies of Ni(II) and Cu(II) complexes with hydrazine carboxamide, 2-[3-methyl-2-thienyl methylene

NASA Astrophysics Data System (ADS)

Chandra, Sulekh; Vandana; Kumar, Suresh

2015-01-01

Schiff's base ligand(L) hydrazine carboxamide, 2-[3-methyl-2-thienyl methylene] and its metal complexes have been synthesized and characterized by elemental analysis, molar conductance, various spectroscopic techniques such as electronic, IR, 1H NMR, mass, EPR. Molar conductance of complexes in DMF solution corresponds to non-electrolyte. Complexes have general composition [M(L)2X2], where M = Ni(II) and Cu(II), X = Cl-, NO3-, CH3COO- and ½SO42-. On the basis of above spectral studies, an octahedral geometry has been assigned for Ni(II) complexes and tetragonal geometry for Cu(II) complexes except [Cu(L)2SO4] which possesses five coordinated trigonal bipyramidal geometry. These metal complexes were also tested for their anticancer, antibacterial and antifungal activities to assess their inhibition potential. Anticancer activity of ligand and its metal complexes were evaluated using SRB fluorometric assay and Adriamycin (ADR) was applied as positive control. Schiff's base ligand and its metal complexes were screened for their antibacterial and antifungal activity against Escherichia coli, Bacillus cereus and Aspergillus niger, Aspergillus flavus, respectively. Kirby-Bauer single disk susceptibility test was used for antibacterial activity and well diffusion method for antifungal activity of the compounds on the used fungi.

Molar uprighting with mini screws: comparison among different systems and relative biomechanical analysis.

PubMed

Musilli, Marino; Marsico, Marco; Romanucci, Annalisa; Grampone, Francesco

2010-01-01

Starting from a segmented approach, the Authors propose 3 different methods of using mini screws during the process of molar uprighting. The first UPG is performed by placing a mini screw in the retromolar area and by applying an elastic chain loaded between the screw and the molar.The second UPG is made by placing a screw in the retro molar area and by using a small cantilever which is active during intrusion and uprighting.The third UPG is made by using a miniscrew placed a few millimeters mesial to the molar to control the vertical force produced by the uprighting with a long cantilever to the frontal teeth.To assist in the understanding of the different clinical indications, the biomechanical differences between these three systems are analyzed. Copyright © 2010 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved.

Efficient and robust compositional two-phase reservoir simulation in fractured media

NASA Astrophysics Data System (ADS)

Zidane, A.; Firoozabadi, A.

2015-12-01

Compositional and compressible two-phase flow in fractured media has wide applications including CO2 injection. Accurate simulations are currently based on the discrete fracture approach using the cross-flow equilibrium model. In this approach the fractures and a small part of the matrix blocks are combined to form a grid cell. The major drawback is low computational efficiency. In this work we use the discrete-fracture approach to model the fractures where the fracture entities are described explicitly in the computational domain. We use the concept of cross-flow equilibrium in the fractures (FCFE). This allows using large matrix elements in the neighborhood of the fractures. We solve the fracture transport equations implicitly to overcome the Courant-Freidricks-Levy (CFL) condition in the small fracture elements. Our implicit approach is based on calculation of the derivative of the molar concentration of component i in phase (cαi ) with respect to the total molar concentration (ci ) at constant volume V and temperature T. This contributes to significant speed up of the code. The hybrid mixed finite element method (MFE) is used to solve for the velocity in both the matrix and the fractures coupled with the discontinuous Galerkin (DG) method to solve the species transport equations in the matrix, and a finite volume (FV) discretization in the fractures. In large scale problems the proposed approach is orders of magnitude faster than the existing models.

Age assessment based on third molar mineralisation : An epidemiological-radiological study on a Central-European population.

PubMed

Hofmann, Elisabeth; Robold, Matthias; Proff, Peter; Kirschneck, Christian

2017-03-01

The method published in 1973 by Demirjian et al. to assess age based on the mineralisation stage of permanent teeth is standard practice in forensic and orthodontic diagnostics. From age 14 onwards, however, this method is only applicable to third molars. No current epidemiological data on third molar mineralisation are available for Caucasian Central-Europeans. Thus, a method for assessing age in this population based on third molar mineralisation is presented, taking into account possible topographic and gender-specific differences. The study included 486 Caucasian Central-European orthodontic patients (9-24 years) with unaffected dental development. In an anonymized, randomized, and blinded manner, one orthopantomogram of each patient at either start, mid or end of treatment was visually analysed regarding the mineralisation stage of the third molars according to the method by Demirjian et al. Corresponding topographic and gender-specific point scores were determined and added to form a dental maturity score. Prediction equations for age assessment were derived by linear regression analysis with chronological age and checked for reliability within the study population. Mineralisation of the lower third molars was slower than mineralisation of the upper third molars, whereas no jaw-side-specific differences were detected. Gender-specific differences were relatively small, but girls reached mineralisation stage C earlier than boys, whereas boys showed an accelerated mineralisation between the ages of 15 and 16. The global equation generated by regression analysis (age = -1.103 + 0.268 × dental maturity score 18 + 28 + 38 + 48) is sufficiently accurate and reliable for clinical use. Age assessment only based on either maxilla or mandible also shows good prognostic reliability.

Analysis of mandibular second molars with fused roots and shallow radicular grooves by using micro-computed tomography.

PubMed

Amoroso-Silva, Pablo; De Moraes, Ivaldo Gomes; Marceliano-Alves, Marilia; Bramante, Clovis Monteiro; Zapata, Ronald Ordinola; Hungaro Duarte, Marco Antonio

2018-01-01

This study aimed to describe the morphological and morphometric aspects of fused mandibular second molars with radicular shallow grooves using micro-computed tomography (CT). Eighty-eight mandibular second molars with fused roots were scanned in a micro-CT scanner at a voxel size of 19.6 μm. After reconstruction, only molars without C-shaped roots and presenting shallow radicular grooves were selected. 30 molars were chosen for further analysis. Canal cross-sections were classified according to Fan's modified classification (C1, C2, C3, and C4) and morphometric parameters at the apical region, examination of accessory foramina and tridimensional configuration were evaluated. Three-dimensional reconstructions indicated a higher prevalence of merging type ( n = 22). According to Fan's modified classification, the C4 configuration was predominant in the 3 apical mm. Roundness median values revealed a more round-shaped canals at 3 mm (0.72) than at 2 (0.63) and 1 (0.61) mm from the apex. High values of major and minor diameters were observed in the canals of these evaluated sections. In addition, few accessory apical foramina were observed at 1 and 2 mm from the apex. The average distance between last accessory foramina and the anatomic apex was 1.17 mm. A less complex internal anatomy is found when a mandibular second molar presents fused roots with shallow radicular grooves. The merging type canal was frequently observed. Moreover, the C4 configuration was predominant at a point 3 mm from the apex and presented rounded canals, large apical diameters, and few accessory foramina. The cervical and middle thirds presented C3 and C1 canal configurations most frequently. A minor morphological complexity is found when fused mandibular second molars present shallow radicular grooves.

Odontometric sex estimation from clinically extracted molar teeth in a North Indian population sample.

PubMed

Tabasum, Qutsia; Sehrawat, Jagmahender Singh; Talwar, Manjit Kaur; Pathak, Raj Kamal

2017-01-01

Different dental features have contributed significantly toward sex determination in the forensic anthropological contexts. Population-specific standards (discriminant functions or regression formulae) have been suggested for various population groups to identify the sex of an unknown individual from dental dimensions and other odontometric features. The main purpose of the present investigation was to examine the degree of sexual dimorphism exhibited by the human teeth of North Indians and identify importance as a forensic tool in sex determination. The linear and diagonal dimensions were recorded at both crown and cementoenamel junction levels of 58 upper and 72 lower molars of 130 Northwest Indian subjects (73 males and 57 females). The measurements were subjected to appropriate statistical analyses to estimate the sex estimation accuracy from lower and upper molars separately. Univariate analyses revealed that molar teeth had greater dimensions in males than the females and the mesiodistal cervical diameter (MDCV) was found to be the most suitable variable for sex determination of the molars. The classification results were in agreement with the previously conducted studies. The index of sexual dimorphism (ISD) was calculated to be higher in lower molars than the upper molars, and the highest sex differences were observed for MDCV based on the ISD. The overall sex estimation accuracy obtained from multivariate discriminant function analysis and regression analysis of pooled data was 70.0% (74% males, 64.9% females) and 66.9% (78.1% males, 52.6% females), respectively. Odontometrics can play a significant role in establishing the biological identity of an unknown individual even from a single tooth in the absence of other sophisticated molecular or biochemical techniques used for this purpose.

Odontometric sex estimation from clinically extracted molar teeth in a North Indian population sample

PubMed Central

Tabasum, Qutsia; Sehrawat, Jagmahender Singh; Talwar, Manjit Kaur; Pathak, Raj Kamal

2017-01-01

Background: Different dental features have contributed significantly toward sex determination in the forensic anthropological contexts. Population-specific standards (discriminant functions or regression formulae) have been suggested for various population groups to identify the sex of an unknown individual from dental dimensions and other odontometric features. The main purpose of the present investigation was to examine the degree of sexual dimorphism exhibited by the human teeth of North Indians and identify importance as a forensic tool in sex determination. Materials and Methods: The linear and diagonal dimensions were recorded at both crown and cementoenamel junction levels of 58 upper and 72 lower molars of 130 Northwest Indian subjects (73 males and 57 females). The measurements were subjected to appropriate statistical analyses to estimate the sex estimation accuracy from lower and upper molars separately. Results: Univariate analyses revealed that molar teeth had greater dimensions in males than the females and the mesiodistal cervical diameter (MDCV) was found to be the most suitable variable for sex determination of the molars. The classification results were in agreement with the previously conducted studies. The index of sexual dimorphism (ISD) was calculated to be higher in lower molars than the upper molars, and the highest sex differences were observed for MDCV based on the ISD. The overall sex estimation accuracy obtained from multivariate discriminant function analysis and regression analysis of pooled data was 70.0% (74% males, 64.9% females) and 66.9% (78.1% males, 52.6% females), respectively. Conclusions: Odontometrics can play a significant role in establishing the biological identity of an unknown individual even from a single tooth in the absence of other sophisticated molecular or biochemical techniques used for this purpose. PMID:29657498

Relationships for mercury and selenium in muscle and ova of gravid freshwater fish.

PubMed

Donald, David B

2016-10-01

At high concentrations, mercury (Hg) is toxic to vertebrates, causing neurological, behavioral, and teratological dysfunction. Selenium (Se) not only is an essential element but also has a high affinity for Hg, binding to organic methyl mercury at a molar ratio of Se/Hg of 1:1. Ratios of <1 increase risk of Hg toxicity. For gravid fish, low concentrations of Se in ova could increase potential for Hg toxicity, compromising embryonic development and fitness of fry. Mercury and selenium concentrations and ratios were investigated in the muscle and ovaries of six species from five families of fish to assess potential for risk to ecological fitness. Molar ratios of Se/Hg in muscle were typically >18 for lower trophic level species but ≤2 for piscivores. For all species combined, the concentrations of Hg in ova were significantly related to concentrations of Hg in muscle. Concentrations of Se in ova versus muscle showed a similar significant relationship that was independent of muscle Hg concentration. Mean ova molar Se/Hg ratios were high, ranging from 69 to 955 for the 6 species. However, a declining relationship between the ova Se/Hg molar ratio and the muscle concentration of Hg for all species combined suggests that development of ova and fry might be compromised for those piscivores with the highest muscle Hg concentrations because of Hg-related Se deficiency.

Solution conformation and flexibility of capsular polysaccharides from Neisseria meningitidis and glycoconjugates with the tetanus toxoid protein

NASA Astrophysics Data System (ADS)

Abdelhameed, Ali Saber; Morris, Gordon A.; Almutairi, Fahad; Adams, Gary G.; Duvivier, Pierre; Conrath, Karel; Harding, Stephen E.

2016-10-01

The structural integrity of meningococcal native, micro-fluidized and activated capsular polysaccharides and their glycoconjugates - in the form most relevant to their potential use as vaccines (dilute solution) - have been investigated with respect to their homogeneity, conformation and flexibility. Sedimentation velocity analysis showed that the polysaccharide size distributions were generally bimodal with some evidence for higher molar mass forms at higher concentration. Weight average molar masses Mw where lower for activated polysaccharides. Conjugation with tetanus toxoid protein however greatly increased the molar mass and polydispersity of the final conjugates. Glycoconjugates had an approximately unimodal log-normal but broad and large molar mass profiles, confirmed by sedimentation equilibrium “SEDFIT MSTAR” analysis. Conformation analysis using HYDFIT (which globally combines sedimentation and viscosity data), “Conformation Zoning” and Wales-van Holde approaches showed a high degree of flexibility - at least as great as the unconjugated polysaccharides, and very different from the tetanus toxoid (TT) protein used for the conjugation. As with the recently published finding for Hib-TT complexes, it is the carbohydrate component that dictates the solution behaviour of these glycoconjugates, although the lower intrinsic viscosities suggest some degree of compaction of the carbohydrate chains around the protein.

Solution conformation and flexibility of capsular polysaccharides from Neisseria meningitidis and glycoconjugates with the tetanus toxoid protein.

PubMed

Abdelhameed, Ali Saber; Morris, Gordon A; Almutairi, Fahad; Adams, Gary G; Duvivier, Pierre; Conrath, Karel; Harding, Stephen E

2016-10-26

The structural integrity of meningococcal native, micro-fluidized and activated capsular polysaccharides and their glycoconjugates - in the form most relevant to their potential use as vaccines (dilute solution) - have been investigated with respect to their homogeneity, conformation and flexibility. Sedimentation velocity analysis showed that the polysaccharide size distributions were generally bimodal with some evidence for higher molar mass forms at higher concentration. Weight average molar masses M w where lower for activated polysaccharides. Conjugation with tetanus toxoid protein however greatly increased the molar mass and polydispersity of the final conjugates. Glycoconjugates had an approximately unimodal log-normal but broad and large molar mass profiles, confirmed by sedimentation equilibrium "SEDFIT MSTAR" analysis. Conformation analysis using HYDFIT (which globally combines sedimentation and viscosity data), "Conformation Zoning" and Wales-van Holde approaches showed a high degree of flexibility - at least as great as the unconjugated polysaccharides, and very different from the tetanus toxoid (TT) protein used for the conjugation. As with the recently published finding for Hib-TT complexes, it is the carbohydrate component that dictates the solution behaviour of these glycoconjugates, although the lower intrinsic viscosities suggest some degree of compaction of the carbohydrate chains around the protein.

A reassessment of the presumed Neandertal remains from San Bernardino Cave, Italy.

PubMed

Benazzi, Stefano; Peresani, Marco; Talamo, Sahra; Fu, Qiaomei; Mannino, Marcello A; Richards, Michael P; Hublin, Jean-Jacques

2014-01-01

In 1986-1987, three human remains were unearthed from macro-unit II of San Bernardino Cave (Berici Hills, Veneto, Italy), a deposit containing a late Mousterian lithic assemblage. The human remains (a distal phalanx, a lower right third molar and a lower right second deciduous incisor) do not show diagnostic morphological features that could be used to determine whether they were from Homo neanderthalensis or Homo sapiens. Despite being of small size, and thus more similar to recent H. sapiens, the specimens were attributed to Neandertals, primarily because they were found in Mousterian layers. We carried out a taxonomic reassessment of the lower right third molar (LRM3; San Bernardino 4) using digital morphometric analysis of the root, ancient DNA analysis, carbon and nitrogen isotope analyses, and direct accelerator mass spectrometry (AMS) radiocarbon dating of dentine collagen. Mitochondrial DNA analysis and root morphology show that the molar belongs to a modern human and not to a Neandertal. Carbon 14 ((14)C) dating of the molar attributes it to the end of the Middle Ages (1420-1480 cal AD, 2 sigma). Carbon and nitrogen isotope analyses suggest that the individual in question had a diet similar to that of Medieval Italians. These results show that the molar, as well as the other two human remains, belong to recent H. sapiens and were introduced in the Mousterian levels post-depositionally. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microtomography evaluation of dental tissue wear surface induced by in vitro simulated chewing cycles on human and composite teeth.

PubMed

Bedini, Rossella; Pecci, Raffaella; Notarangelo, Gianluca; Zuppante, Francesca; Persico, Salvatore; Di Carlo, Fabio

2012-01-01

In this study a 3D microtomography display of tooth surfaces after in vitro dental wear tests has been obtained. Natural teeth have been compared with prosthetic teeth, manufactured by three different polyceramic composite materials. The prosthetic dental element samples, similar to molars, have been placed in opposition to human teeth extracted by paradontology diseases. After microtomography analysis, samples have been subjected to in vitro fatigue test cycles by servo-hydraulic mechanical testing machine. After the fatigue test, each sample has been subjected again to microtomography analysis to obtain volumetric value changes and dental wear surface images. Wear surface images were obtained by 3D reconstruction software and volumetric value changes were measured by CT analyser software. The aim of this work has been to show the potential of microtomography technique to display very clear and reliable wear surface images. Microtomography analysis methods to evaluate volumetric value changes have been used to quantify dental tissue and composite material wear.

C-shaped maxillary permanent first molar: a case report and literature review.

PubMed

Martins, Jorge N R; Quaresma, Sérgio; Quaresma, Maria Carlos; Frisbie-Teel, Jared

2013-12-01

The C-shaped configuration is rare in the upper first molar.The purpose of this article is to present 2 cases diagnosed during endodontic therapy and perform a literature review of this anatomy in the upper first molar. Endodontic therapy was performed by using a dental operating microscope and a cone-beam computed tomography analysis for better understanding of this anatomy. A literature search was conducted to identify and compare all the published cases of C-shaped upper first molar. Before the cases reported in this article, only 5 cases were available in the published literature. Three different types of C-shaped configurations in the upper first molar have been presented. The C-shaped maxillary first molar is a rare anatomic configuration. The use of the dental operating microscope may help in the endodontic therapy of these cases. Three types of C-shaped configurations have been reported; the fusion of the distobuccal root with the palatal root appears to be the most usual one. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

[Distal movement of the mandibular dentition in the treatment of patients with Class III skeletal pattern].

PubMed

Mou, Lan; Xu, Gengchi; Han, Yaohui; Ge, Zhenlin

2015-06-01

To evaluate the outcome of patients with skeletal Class III malocclusion treated with extraction of mandibular third molars and distalization of molars using implant anchorage combined with MBT appliance. Fifteen patients (mean age 24.0 ± 5.8) with skeletal Class III malocclusion were selected. The mandibular third molars were extracted and the mandibular molars were moved distally using implant combined with MBT appliance. Cephalometric analysis was carried out before and after treatment. After active treatment, ANB, Wits distance, AB-NP and the distance between upper and lower lip position to SnPg' increased by 1.65° ± 1.04°, (4.39 ± 1.93) mm, 3.20° ± 1.61° and (1.13 ± 0.99) mm, respectively. The differences were statistically significant (P < 0.05). The skeletal Class III patients in the permanent dentition could be treated successfully with extraction of mandibular third molars and distalization of mandibular molars using implant anchorage combined with MBT appliance. The soft-tissue profile was improved.

Predictive factors of difficulty in lower third molar extraction: A prospective cohort study

PubMed Central

Alvira-González, Joaquín; Valmaseda-Castellón, Eduard; Quesada-Gómez, Carmen; Gay-Escoda, Cosme

2017-01-01

Background Several publications have measured the difficulty of third molar removal, trying to establish the main risk factors, however several important preoperative and intraoperative variables are overlooked. Material and Methods A prospective cohort study comprising a total of 130 consecutive lower third molar extractions was performed. The outcome variables used to measure the difficulty of the extraction were operation time and a 100mm visual analogue scale filled by the surgeon at the end of the surgical procedure. The predictors were divided into 4 different groups (demographic, anatomic, radiographic and operative variables). A descriptive, bivariate and multivariate analysis of the data was performed. Results Patients’ weight, the presence of bulbous roots, the need to perform crown and root sectioning of the lower third molar and Pell and Gregory 123 classification significantly influenced both outcome variables (p< 0.05). Conclusions Certain anatomical, radiological and operative variables appear to be important factors in the assessment of surgical difficulty in the extraction of lower third molars. Key words:Third molar, surgical extraction, surgical difficulty. PMID:27918736

Potential Moderating Effects of Selenium on Mercury Uptake and Selenium:Mercury Molar Ratios in Fish From Oak Ridge and Savannah River Site - 12086

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burger, Joanna; Gochfeld, Michael; Donio, Mark

2012-07-01

Mercury contamination is an important remediation issue at the U.S. Department of Energy's (DOE) Oak Ridge Reservation and to a lesser extent at other DOE sites because of the hazard it presents, potential consequences to humans and eco-receptors, and completed pathways, to offsite receptors. Recent work has emphasized that selenium might ameliorate the toxicity of mercury, and we examine the selenium:mercury (Se:Hg) molar ratios in fish from Oak Ridge, and compare them to Se:Hg molar ratios in fish from the Savannah River. Selenium/mercury molar ratios varied considerably among and within fish species. There was considerable variation in the molar ratiosmore » for individual fish (as opposed to mean ratios by species) for freshwater fish from both sites. The inter-individual variation in molar ratios indicates that such that the molar ratios of mean Se and Hg concentrations may not be representative. Even for fish species with relatively low mercury levels, some individual fish have molar ratios less than unity, the value sometime thought to be protective. Selenium levels varied narrowly regardless of fish size, consistent with homeostatic regulation of this essential trace element. The data indicate that considerable attention will need to be directed toward variations and variances, as well as the mechanisms of the interaction of selenium and mercury, before risk assessment and risk management policies can use this information to manage mercury pollution and risk. Even so, if there are high levels of selenium in the fish from Poplar Creek on Oak Ridge, then the potential exists for some amelioration of adverse health effects, on the fish themselves, predators that eat them, and people who consume them. This work will aid DOE because it will allow managers and scientists to understand another aspect that affects fate and transport of mercury, as well as the potential effects of methylmercury in fish for human and ecological receptors. The variability within fish species, however, suggests that the relative Se:Hg molar ratios in fish are not stable enough to be used in risk assessment at this time. Nor is it known how much excess selenium is required to confer any degree of protectiveness. That is, in conducting risk assessments, it is not possible to determine the spread of ratios, which would be needed for probabilistic risk assessment. Significantly more fish samples per species are required to begin to generate data that would allow it use in risk assessment. Adding Se:Hg molar ratios seems to complicate risk assessment for the potential adverse effects of mercury exposure, and using mercury levels at this time remains the most viable option. (authors)« less

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

PubMed Central

Pramojanee, Sakarat; Thaiupathump, Trasapong

2013-01-01

Purpose This study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age. Materials and Methods Indirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated. Results The correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively. Conclusion It might be possible to predict chronological age from the eruption height of the wisdom teeth. PMID:24380069

Ectopic eruption of first permanent molars: presenting features and associations.

PubMed

Mooney, G C; Morgan, A G; Rodd, H D; North, S

2007-09-01

To investigate presenting features of ectopically erupting first permanent molars and associations with other dental anomalies. Prospective convenience study. 28 panoral radiographs were collected, over a 24-month period, of 7-11 year-old children with radiographic evidence of ectopic eruption of first permanent molars who presented to a Dental Teaching Hospital in the North of England. A further 20 radiographs were collected of matched patients with no evidence of ectopic molar eruption. All radiographs were analysed under standard conditions to record the distribution and type of ectopic eruption (if present). In addition, the presence of the following dental anomalies was noted: cleft lip and/or palate; supernumerary teeth; hypodontia, and infraocclusion of primary molars. Chi-squared analysis was performed to determine any significant differences in the frequency of these dental anomalies between ectopic molar and control groups. For patients with ectopic molar eruption, the majority demonstrated ectopic eruption of either one or two first permanent molars (32% and 57% of subjects respectively). There were a similar proportion of 'jumps' and 'holds'. 92% of these were maxillary teeth and there was equal left and right distribution. Interestingly, a positive record of ectopic eruption was only documented in the dental records of 35.7% of these subjects. Children with ectopic eruption were significantly more likely to have at least one additional dental anomaly than was the case for the control group (60.7% versus 25%). Notably, primary molar infraocclusion and cleft lip/palate were significantly more frequent in the ectopic group. This study, the first in a British population, has identified a significant association between ectopic eruption of first permanent molars and other dental anomalies. A multifactorial aetiology is thus supported and clinicians should be alert to the co-existence of ectopic eruption and other dental anomalies.

Morphology of mandibular first molars analyzed by cone-beam computed tomography in a Korean population: variations in the number of roots and canals.

PubMed

Kim, Sin-Young; Kim, Bom Sahn; Woo, Jein; Kim, Yemi

2013-12-01

The aim of this study was to determine the root and canal morphology of the mandibular first molars in a Korean population of Mongolian origin by retrospective analysis of a large number of cone-beam computed tomography (CBCT) images. A total of 976 subjects with bilateral mandibular first molars were examined by using in vivo CBCT methods. The number and configuration of roots, the number of root canals, and the canal configuration based on Vertucci's classification were determined. Overall, 25.82% of examined molars had 3 roots, 73.51% had 2 roots, and 0.67% had 1 root. The incidence of fourth canal was 50.36%. A right-sided predominance was noted for extra distal roots (P < .001), whereas a left-sided predominance was observed for extra distal canals (P < .001). No significant sex-related differences were shown for their prevalence. The bilateral prevalence rate was 69.13% for extra distal roots and 78.08% for extra distolingual (DL) canals. In the mesial roots, type IV canal was the most frequent (76.86% for 2-rooted molars and 72.96% for 3-rooted molars). In the distal roots, type l was the most common (66.62% for 2-rooted molars and 99.40%-100% for 3-rooted molars). The incidence of 2 canals in distobuccal roots, first reported in this study, was 0.15%. Among mandibular first molars, there is a high prevalence of a separate DL root and/or a separate DL canal, and such molars commonly have 4 canals in the Korean population. CBCT is a useful tool for determining root and canal morphology. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Surface morphology, optical, and electrochromic properties of nanostructured nickel ferrite (NiFe2O4) prepared by sol-gel method: effects of Ni/Fe molar ratios

NASA Astrophysics Data System (ADS)

Bazhan, Z.; Ghodsi, F. E.; Mazloom, J.

2016-05-01

Nanostructured nickel ferrite (NF) was prepared by the sol-gel method and calcined at 500 °C for 2 h. The effect of Ni/Fe molar ratios (0, 10, 30, 50 %) on structural, morphological, compositional, optical, and magnetic properties of samples was investigated using analytical tools. XRD patterns indicated the presence of hematite phase in the pure and 10 % NF samples. The samples of 30 and 50 % Ni/Fe molar ratios showed the formation of nickel ferrite structure. Using AFM images, power spectrum density analysis were performed for Ni/Fe with different molar ratio. Also the effect of thickness on morphology of 30 % sample was studied. The fractal dimension increases by increasing the Ni/Fe molar ratio. Optical parameters were evaluated by theoretical approach, and compositional dependence of these parameters was discussed comprehensively. Band gap narrowing was observed in nickel ferrite thin films by increasing the nickel contents from 10 to 50 %. Magnetic analysis revealed that increasing nickel content improved the saturation magnetization. Electrochemical measurements indicated that NF thin films have higher total charge density rather than Fe2O3 thin films and the ion storage capacitance of NF thin films increased by increasing the Ni/Fe content.

Caveats when Analyzing Ultra-high Molar Mass Polymers by SEC

USDA-ARS?s Scientific Manuscript database

The analysis of ultra-high molar mass (M > 1 million g/mol) polymers via size-exclusion chromatography (SEC) presents a number of non-trivial challenges. Dissolution and full solvation may take days, as is the case for cellulose dissolution in non-complexing non degrading solvents; very low concent...

Does grafting of third molar extraction sockets enhance periodontal measures in 30- to 35-year-old patients?

PubMed

Hassan, Khalid S; Marei, Hesham F; Alagl, Adel S

2012-04-01

This study was designed to evaluate the use of xenograft plus a membrane as grafting material for periodontal osseous defects distal to the mandibular second molar compared with nongrafted extraction sites after removal of impacted mandibular third molars. We performed a single-blind, randomized, controlled clinical trial, and the sample comprised of subjects at high risk for the development of periodontal osseous defects distal to the second molar after third molar extraction (aged 30-35 years), pre-existing osseous defects distal to the second molar, and horizontal third molar impaction. The predictor variable was the treatment status of the second molar osseous defects. The third molar extraction sites were grafted with an anorganic xenograft plus a membrane. The other sites received a full-thickness flap and extraction of the third molar without placement of the grafting materials. The outcome variables were the change in gingival index, pocket probing depth, and clinical attachment level on the distobuccal aspect of the second molar preoperatively and at 3, 6, 9, and 12 months after surgery. Data were statistically analyzed by multivariate analysis of variance, and the statistical significance was set at P < .05. The study was composed of 28 sites that were selected by use of a split-mouth design for each patient, and this was randomly determined through a biased coin randomization. Twelve months after third molar removal, there was a statistically significant gain in the clinical attachment level and a reduction in the probing pocket depth in the grafted sites compared with the nongrafted sites (P < .001). Moreover, there was a significant difference in the alveolar bone height during the monitoring periods for the grafted sites compared with the nongrafted sites (P < .001). Grafting of osseous defects distal to mandibular second molars with an anorganic xenograft plus a membrane predictably resulted in a significant reduction in the probing pocket depth, clinical attachment level gain, and bone fill, which suggests that grafting the extraction sites with an anorganic xenograft plus a membrane could prevent periodontal disease in the future. Published by Elsevier Inc.

Mobility of nutrients and trace metals during weathering in the late Archean

NASA Astrophysics Data System (ADS)

Hao, Jihua; Sverjensky, Dimitri A.; Hazen, Robert M.

2017-08-01

The evolution of the geosphere and biosphere depends on the availability of bio-essential nutrients and trace metals. Consequently, the chemical and isotopic variability of trace elements in the sedimentary record have been widely used to infer the existence of early life and fluctuations in the near-surface environment on the early Earth, particularly fluctuations in the redox state of the atmosphere. In this study, we applied late Archean weathering models (Hao et al., 2017), developed to estimate the behavior of major elements and the composition of late Archean world average river water, to explore the behavior of nutrient and trace metals and their potential for riverine transport. We focused on P, Mn, Cr, and Cu during the weathering of olivine basalt. In our standard late Archean weathering model (pCO2,g = 10-1.5 bars, pH2,g = 10-5.0 bars), crustal apatite was totally dissolved by the acidic rainwater during weathering. Our model quantitatively links the pCO2,g of the atmosphere to phosphate levels transported by rivers. The development of late Archean river water (pH = 6.4) resulted in riverine phosphate of at least 1.7 μmolar, much higher than at the present-day. At the end of the early Proterozoic snowball Earth event when pCO2,g could be 0.01-0.10 bars, river water may have transported up to 70 μmolar phosphate, depending on the availability of apatite, thereby stimulating high levels of oxygenic photosynthesis in the marine environment. Crustal levels of Mn in olivine dissolved completely during weathering, except at large extents of weathering where Mn was stored as a component of a secondary carbonate mineral. The corresponding Mn content of river water, about 1.2 μmolar, is higher than in modern river water. Whiffs of 10-5 mole O2 gas or HNO3 kg-1 H2O resulted in the formation of pyrolusite (MnO2) and abundant hematite and simultaneous dramatic decreases in the concentration of Mn(II) in the river water. Chromite dissolution resulted in negligible dissolved Cr in Archean river water. However, amorphous Cr(OH)3 representing easily-weatherable Cr-bearing minerals dissolved totally during the weathering simulations, resulting in concentrations of Cr(III) in the river water of up to 0.14 μmolar, higher than at the present-day. Late Archean weathering of accessory chalcopyrite produced chalcocite and bornite, and extremely low concentrations of Cu (<10-15 molar) because of the low solubilities of the copper sulfides. However, pulses of either O2,g or HNO3 produced native copper, chalcocite, and bornite, much more hematite, and river water containing levels of dissolved Cu comparable to the present-day. Copper mineralogy predicted by weathering models might provide a new correlation with evidence from studies of copper mineral evolution. Overall, our results implied that the redox state of the atmosphere, the pH of surface waters, and the availability of easily-weatherable minerals are all important factors controlling the dissolution of trace elements in river water. Interpretation of the sedimentary signatures of trace elements should consider not only the redox state but also the pH and availability of accessory minerals.

Numeric simulation of occlusal interferences in molars restored with ultrathin occlusal veneers.

PubMed

Magne, Pascal; Cheung, Raymond

2017-01-01

Selecting material for a minimally invasive occlusal veneer reconstruction concept requires an understanding of how stresses are distributed during functional and parafunctional forces. The purpose of this in vitro study was to investigate stress distribution in a maxillary molar restored with ultrathin occlusal veneers and subjected by an antagonistic mandibular molar to clenching and working and nonworking movements. A maxillary first molar was modeled from microcomputed tomography (micro-CT) data, using medical image processing software, stereolithography editing/optimizing software, and finite element software. Simulated ultrathin occlusal veneer materials were used. The mandibular molar antagonist was a solid nondeformable geometric entity. Loads simulated clenching, working, and nonworking movements with loading of 500 N. The values of the maximum principal stress were recorded. In the clenching load situation, maximum tensile stresses were located at the occlusal veneer (52 MPa for composite resin versus 47 MPa for ceramic). In the working movement, significant additional tensile stresses were found on the palatal root (87 MPa for composite resin and 85 MPa for ceramic). In the nonworking movement, tensile stress on the ultrathin occlusal veneer increased to 118 MPa for composite resin and 143 MPa for ceramic veneers. Tensile stress peaks shifted to the mesiobuccal root (75 MPa for composite resin and 74 MPa for ceramic). The topography of stresses generated by the various occlusal interferences were clearly identified. Significant tensile stress concentrations were found within the restoration's occlusal topography and root, with the nonworking interference being the most harmful and also the most revealing of the difference between the composite resin and ceramic ultrathin occlusal veneers. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Prospective analysis of frequency and contributing factors of nerve injuries following third-molar surgery.

PubMed

Janakiraman, Eswari Natt; Alexander, Mohan; Sanjay, Pasupathy

2010-05-01

The objective of this prospective study was to determine the incidence of injury to the inferior alveolar and lingual nerves following surgical removal of impacted mandibular third molars and to evaluate the various factors contributing to the same. A total of 119 patients underwent mandibular third-molar removal during the period of 11 months. Of 119, 3 inferior alveolar nerve and 5 lingual nerve injuries were encountered. Various factors such as lingual retraction, surgical time, operator experience, radiologic findings contributing to the injury were correlated and analyzed.

Prevalence of Taurodont molars in a North Indian population.

PubMed

Bharti, Ramesh; Chandra, Anil; Tikku, Aseem Prakash; Arya, Deeksha

2015-01-01

It is very important for dentists to be familiar with anomalies of teeth not only for the clinical complications but also their management. Taurodontism also provides a valuable clue in detecting its association with various syndromes and other systemic conditions. The purpose of this study was to assess the prevalence of Taurodont molars among a North Indian population. A total of 1000 patients' full-mouth periapical radiographs were screened. The radiographs were evaluated under optimal conditions using double magnifying glasses. A total of 7615 molars (including third molars) were evaluated. The relative incidence and the correlations regarding the location of Taurodont teeth (right versus left side and maxillary versus mandibular) were analyzed using the Chi-square test. Twenty-eight patients were found to have a Taurodont molar (11 women and 17 men [P = 0.250]). The prevalence of Taurodont molar was 2.8%. Males had a higher prevalence rate than females (3.4% vs. 2.2%, respectively). A cluster analysis of total Taurodonts in the mandible (45%) versus maxilla (55%) of both males and females combined showed a statistically significant difference (P < 0.05). The occurrence of Taurodontism is basically based on racial expression in different populations. These variations in prevalence between different populations may be due to ethnic variations. The occurrence of Taurodont molars among this Indian population was rare.

Prevalence of Extra Roots in Permanent Mandibular First Molars in Iranian Population: A CBCT Analysis.

PubMed

Rahimi, Saeed; Mokhtari, Hadi; Ranjkesh, Bahram; Johari, Masoomeh; Frough Reyhani, Mohammad; Shahi, Shahriar; Seif Reyhani, Sina

2017-01-01

Having knowledge about the anatomy of root canal system is essential for success of endodontic treatment. The present study used cone-beam computed tomography (CBCT), to evaluate the prevalence of third root in mandibular first molars in a selected Iranian population. A total of 386 CBCT images from subjects referred to oral and maxillofacial radiology department of dental faculty of Tabriz University of Medical Sciences from 2011 to 2013 were selected and evaluated for this study and the cases with well-developed permanent mandibular first molars were included. The 3D images were reconstructed in axial cross sections and evaluated by two endodontists for the presence of the third extra lingual (radix entomolaris) or buccal (radix paramolaris) root. The chi-squared test was used to evaluate the relationship between gender and bilateral incidence of extra roots in mandibular first molars. The distribution of three-rooted mandibular first molars with an additional root was 3%, (3.53% in female and 2.50% in male patients). There was no significant relationship between gender and bilateral occurrence of three-rooted mandibular first molars. The occurrence of three-rooted mandibular first molars in Iranian population is not uncommon which should be taken into consideration by the dental practitioners during root canal treatment of these teeth.

Dental and skeletal changes after intraoral molar distalization with sectional jig assembly.

PubMed

Gulati, S; Kharbanda, O P; Parkash, H

1998-09-01

The present study was conducted on 10 subjects to evaluate dental and skeletal changes after intraoral molar distalization. The maxillary molars were distalized with a sectional jig assembly. Sentalloy open coil springs were used to exert 150 gm of force for a period of 12 weeks. A modified Nance appliance was the main source of anchorage. The pre- and postdistalization records included dental study casts, clinical photographs, and cephalograms. A total of 665 readings recorded from lateral cephalograms and dental casts were subjected to statistical analysis. The mean distal movement of the first molar was 2.78 mm, which was highly significant (o < 0.001). It moved distally at the rate of 0.86 mm/month. There was clinically some distal tipping (3.50 degrees) and distopalatal rotation (2.40 degrees). These changes were statistically significant (p < 0.001). The second molars accompanied the first molars and moved distally by nearly the same amount. There was 1.00 mm increase in the overjet and 2.60 degrees mesial tip of second premolar. The changes in the facial skeleton and dentition bases were minimal and statistically not significant. However, there was clockwise rotation of the mandible of 1.30 degrees that was statistically significant. This was the result of molar extrusion (1.60 mm).

Effect of orthodontic treatment involving first premolar extractions on mandibular third molar angulation and retromolar space.

PubMed

Mendoza-García, Luz-Victoria; Vaillard-Jiménez, Esther; García-Rocha, Araceli; Bellot-Arcís, Carlos; Paredes-Gallardo, Vanessa

2017-03-01

Third molars present more problems than other teeth because they are the last teeth to erupt, and so it is important to assess their development when designing an orthodontic treatment plan. The aim of this study was to compare the angulation of the mandibular third molar and retromolar space before and after orthodontic treatment in cases involving first premolar extraction. 76 patients, 59 women (77.63%) and 17 men (22.36%), were recruited from the Orthodontics Clinic at Benemérita Universidad Autónoma de Puebla (Mexico). Panoramic radiographs were analyzed before and after orthodontic treatment that included first premolar extractions, measuring retromolar space (RS) and the angles formed by the intersection of the axes of the third and second molar (α) and the intersection of the axis of the mandibular plane and third molar (β). The data obtained underwent statistical analysis. The angle α and β showed statistically significant differences on the left side in women. In men, only the right side α angle showed significant differences. Retromolar space increased significantly on both sides for both sexes. Third molar angulation presents different behaviors between men and women, with greater verticalization in women. Key words: Third molar, retromolar space, orthodontics.

Effect of orthodontic treatment involving first premolar extractions on mandibular third molar angulation and retromolar space

PubMed Central

Vaillard-Jiménez, Esther; García-Rocha, Araceli; Bellot-Arcís, Carlos; Paredes-Gallardo, Vanessa

2017-01-01

Background Third molars present more problems than other teeth because they are the last teeth to erupt, and so it is important to assess their development when designing an orthodontic treatment plan. The aim of this study was to compare the angulation of the mandibular third molar and retromolar space before and after orthodontic treatment in cases involving first premolar extraction. Material and Methods 76 patients, 59 women (77.63%) and 17 men (22.36%), were recruited from the Orthodontics Clinic at Benemérita Universidad Autónoma de Puebla (Mexico). Panoramic radiographs were analyzed before and after orthodontic treatment that included first premolar extractions, measuring retromolar space (RS) and the angles formed by the intersection of the axes of the third and second molar (α) and the intersection of the axis of the mandibular plane and third molar (β). Results The data obtained underwent statistical analysis. The angle α and β showed statistically significant differences on the left side in women. In men, only the right side α angle showed significant differences. Retromolar space increased significantly on both sides for both sexes. Conclusions Third molar angulation presents different behaviors between men and women, with greater verticalization in women. Key words:Third molar, retromolar space, orthodontics. PMID:28298970

Piezoelectric Versus Conventional Rotary Techniques for Impacted Third Molar Extraction

PubMed Central

Jiang, Qian; Qiu, Yating; Yang, Chi; Yang, Jingyun; Chen, Minjie; Zhang, Zhiyuan

2015-01-01

Abstract Impacted third molars are frequently encountered in clinical work. Surgical removal of impacted third molars is often required to prevent clinical symptoms. Traditional rotary cutting instruments are potentially injurious, and piezosurgery, as a new osteotomy technique, has been introduced in oral and maxillofacial surgery. No consistent conclusion has been reached regarding whether this new technique is associated with fewer or less severe postoperative sequelae after third molar extraction. The aim of this study was to compare piezosurgery with rotary osteotomy techniques, with regard to surgery time and the severity of postoperative sequelae, including pain, swelling, and trismus. We conducted a systematic literature search in the Cochrane Library, PubMed, Embase, and Google Scholar. The eligibility criteria of this study included the following: the patients were clearly diagnosed as having impacted mandibular third molars; the patients underwent piezosurgery osteotomy, and in the control group rotary osteotomy techniques, for removing impacted third molars; the outcomes of interest include surgery time, trismus, swelling or pain; the studies are randomized controlled trials. We used random-effects models to calculate the difference in the outcomes, and the corresponding 95% confidence interval. We calculated the weighted mean difference if the trials used the same measurement, and a standardized mean difference if otherwise. A total of seven studies met the eligibility criteria and were included in our analysis. Compared with rotary osteotomy, patients undergoing piezosurgery experienced longer surgery time (mean difference 4.13 minutes, 95% confidence interval 2.75–5.52, P < 0.0001). Patients receiving the piezoelectric technique had less swelling at postoperative days 1, 3, 5, and 7 (all Ps ≤0.023). Additionally, there was a trend of less postoperative pain and trismus in the piezosurgery groups. The number of included randomized controlled trials and the sample size of each trial were relatively small, double blinding was not possible, and cost analysis was unavailable due to a lack of data. Our meta-analysis indicates that although patients undergoing piezosurgery experienced longer surgery time, they had less postoperative swelling, indicating that piezosurgery is a promising alternative technique for extraction of impacted third molars. PMID:26469902

Synthesis, spectral and thermal studies of the newly hydrogen bonded charge transfer complex of o-phenylenediamine with pi acceptor picric acid.

PubMed

Khan, Ishaat M; Ahmad, Afaq

2010-10-01

Newly proton or charge transfer complex [(OPDH)(+)(PA)(-)] was synthesized by the reaction of the donor, o-phenylenediamine (OPD) with acceptor, 2,4,6-trinitrophenol (PAH). The chemical reaction has occurred via strong hydrogen bonding followed by migration of proton from acceptor to donor. UV-vis, (1)H NMR and FTIR spectra, in addition to the thermal and elemental analysis were used to confirm the proposed occurrence of the chemical reaction and to investigate the newly synthesized solid CT complex. The stoichiometry of the CT complex was found to be 1:1. The formation constant and molar extinction coefficient of the CT complex were evaluated by the Benesi-Hildebrand equation. Copyright 2010 Elsevier B.V. All rights reserved.

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars

PubMed Central

Abarca, J.; Zaror, C.; Monardes, H.; Hermosilla, V.; Muñoz, C.; Cantin, M.

2015-01-01

SUMMARY Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3–5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24–0.33 mm in maxillary first molars and between 0.25–0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully. PMID:25937698

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars.

PubMed

Abarca, J; Zaror, C; Monardes, H; Hermosilla, V; Muñoz, C; Cantin, M

2014-06-01

Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3-5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24-0.33 mm in maxillary first molars and between 0.25-0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully.

Comparing the Efficiency of Two Different Extraction Techniques in Removal of Maxillary Third Molars: A Randomized Controlled Trial.

PubMed

Edward, Joseph; Aziz, Mubarak A; Madhu Usha, Arjun; Narayanan, Jyothi K

2017-12-01

Extractions are routine procedures in dental surgery. Traditional extraction techniques use a combination of severing the periodontal attachment, luxation with an elevator, and removal with forceps. A new technique of extraction of maxillary third molar is introduced in this study-Joedds technique, which is compared with the conventional technique. One hundred people were included in the study, the people were divided into two groups by means of simple random sampling. In one group conventional technique of maxillary third molar extraction was used and on second Joedds technique was used. Statistical analysis was carried out with student's t test. Analysis of 100 patients based on parameters showed that the novel joedds technique had minimal trauma to surrounding tissues, less tuberosity and root fractures and the time taken for extraction was <2 min while compared to other group of patients. This novel technique has proved to be better than conventional third molar extraction technique, with minimal complications. If Proper selection of cases and right technique are used.

Clinical measurement of force systems upon activation of transpalatal arch in the treatment of unilateral crossbite.

PubMed

Yoshida, N; Koga, Y; Jost-Brinkmann, P G; Kobayashi, K

2003-01-01

in this study, forces and moments acting on the molars were theoretically determined by means of small-deflection analysis when an asymmetric third-order activation of the TPA was carried out. the transpalatal arch (TPA) is used to correct unilateral crossbites through the application of buccal root torque to the anchorage molar and lingual root torque to the contralateral molar in crossbite, combined with expansion. Unfortunately, the complex force systems created at the molars upon activation of the TPA cannot be easily estimated. our computations revealed that the vertical forces developed on the molars when both ends of the TPA are inserted into the lingual sheaths (two-couple system) is four-times greater than those when only one end is tied to the lingual sheath as a single-point contact (one-couple system). we propose a method of clinical estimation of the force system in a two-couple system by directly measuring the vertical force produced by the one-couple system.

Predictive factors of difficulty in lower third molar extraction: A prospective cohort study.

PubMed

Alvira-González, J; Figueiredo, R; Valmaseda-Castellón, E; Quesada-Gómez, C; Gay-Escoda, C

2017-01-01

Several publications have measured the difficulty of third molar removal, trying to establish the main risk factors, however several important preoperative and intraoperative variables are overlooked. A prospective cohort study comprising a total of 130 consecutive lower third molar extractions was performed. The outcome variables used to measure the difficulty of the extraction were operation time and a 100mm visual analogue scale filled by the surgeon at the end of the surgical procedure. The predictors were divided into 4 different groups (demographic, anatomic, radiographic and operative variables). A descriptive, bivariate and multivariate analysis of the data was performed. Patients' weight, the presence of bulbous roots, the need to perform crown and root sectioning of the lower third molar and Pell and Gregory 123 classification significantly influenced both outcome variables (p< 0.05). Certain anatomical, radiological and operative variables appear to be important factors in the assessment of surgical difficulty in the extraction of lower third molars.

Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: spectral, thermal, XRD and antimicrobial studies.

PubMed

Sundararajan, M L; Jeyakumar, T; Anandakumaran, J; Karpanai Selvan, B

2014-10-15

Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, (1)H NMR, (13)C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base. Copyright © 2014 Elsevier B.V. All rights reserved.

Efficacy of Platelet-Rich Fibrin After Mandibular Third Molar Extraction: A Systematic Review and Meta-Analysis.

PubMed

Al-Hamed, Faez Saleh; Tawfik, Mohamed Abdel-Monem; Abdelfadil, Ehab; Al-Saleh, Mohammed A Q

2017-06-01

To assess the effect of platelet-rich fibrin (PRF) on the healing process of the alveolar socket after surgical extraction of the mandibular third molars. PubMed, the Cochrane Central Register of Controlled Trials, Scopus, and relevant journals were searched using a combination of specific keywords ("platelet-rich fibrin," "oral surgery," and "third molar"). The final search was conducted on November 2, 2015. Randomized controlled clinical trials, as well as controlled clinical trials, aimed at comparing the effect of PRF versus natural healing after extraction of mandibular third molars were included. Five randomized controlled trials and one controlled clinical trial were included. There were 335 extractions (168 with PRF and 167 controls) in 183 participants. Considerable heterogeneity in study characteristics, outcome variables, and estimated scales was observed. Positive results were generally recorded for pain, trismus, swelling, periodontal pocket depth, soft tissue healing, and incidence of localized osteitis, but not in all studies. However, no meta-analysis could be conducted for such variables because of the different measurement scales used. The qualitative and meta-analysis results showed no significant improvement in bone healing with PRF-treated sockets compared with the naturally healing sockets. Within the limitations of the available evidence, PRF seems to have no beneficial role in bone healing after extraction of the mandibular third molars. Future standardized randomized controlled clinical trials are required to estimate the effect of PRF on socket regeneration. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Isentropic expansion and related thermodynamic properties of non-ionic amphiphile-water mixtures.

PubMed

Reis, João Carlos R; Douhéret, Gérard; Davis, Michael I; Fjellanger, Inger Johanne; Høiland, Harald

2008-01-28

A concise thermodynamic formalism is developed for the molar isentropic thermal expansion, ES,m = ( partial differential Vm/ partial differential T)(Sm,x), and the ideal and excess quantities for the molar, apparent molar and partial molar isentropic expansions of binary liquid mixtures. Ultrasound speeds were determined by means of the pulse-echo-overlap method in aqueous mixtures of 2-methylpropan-2-ol at 298.15 K over the entire composition range. These data complement selected extensive literature data on density, isobaric heat capacity and ultrasound speed for 9 amphiphile (methanol, ethanol, propan-1-ol, propan-2-ol, 2-methylpropan-2-ol, ethane-1,2-diol, 2-methoxyethanol, 2-ethoxyethanol or 2-butoxyethanol)-water binary systems, which form the basis of tables listing molar and excess molar isobaric expansions and heat capacities, and molar and excess molar isentropic compressions and expansions at 298.15 K and at 65 fixed mole fractions spanning the entire composition range and fine-grained in the water-rich region. The dependence on composition of these 9 systems is graphically depicted for the excess molar isobaric and isentropic expansions and for the excess partial molar isobaric and isentropic expansions of the amphiphile. The analysis shows that isentropic thermal expansion properties give a much stronger response to amphiphile-water molecular interactions than do their isobaric counterparts. Depending on the pair property-system, the maximum excess molar isentropic value is generally twenty- to a hundred-fold greater than the corresponding maximum isobaric value, and occurs at a lower mole fraction of the amphiphile. Values at infinite dilution of the 9 amphiphiles in water are given for the excess partial molar isobaric heat capacity, isentropic compression, isobaric expansion and isentropic expansion. These values are interpreted in terms of the changes occurring when amphiphile molecules cluster into an oligomeric form. Present results are discussed from theoretical and experimental thermodynamic viewpoints. It is concluded that isentropic thermal expansion properties constitute a new distinct resource for revealing particular features and trends in complex mixing processes, and that analyses using these new properties compare favourably with conventional approaches.

Contaminant profiles of two species of shorebirds foraging together at two neighboring sites in south San Francisco Bay, California

USGS Publications Warehouse

Hui, Clifford A.; Takekawa, John Y.; Warnock, Sarah E.

2001-01-01

The San Francisco Bay estuary isused by over one million shorebirds during springmigration and is home to several hundred thousandduring the winter. Most shorebird use occurs in thesouthern reach of the estuary (South Bay). Thereduced water circulation and discharge fromindustrial sources in the South Bay are responsiblefor the highest levels of some trace elements in theestuary. Wintering shorebirds have been found to havestrong site fidelity to areas as small as a fewkilometers in the South Bay, which may increase theirexposure to contaminants near local point sources. Inaddition, different shorebird species foraging at thesame site have been shown to have differentcontaminant burdens. Thus, our objectives were totest whether contaminant burdens differed by species,or whether contaminant burdens differed in shorebirdscollected at adjacent sites. We examined thecontaminant profiles of two species of shorebirds,long-billed dowitchers (Limnodromus scolopaceus)and western sandpipers (Calidris mauri) thatforage together at two sites, Hayward and Newark,separated by 8 km in the South Bay. We usedmultivariate analysis of variance tests to compare thecomposition of 14 elemental analytes in their livertissues and estimated their molar ratios of Hg and Se. Composite samples were used for contaminant analysesbecause of the small body size of the shorebirds. Seven elemental analytes (Ag, Ba, Be, Cr, Ni, Pb, V)were below detection limits in a majority of thesamples so statistical analyses were precluded. Inthe measurable analytes (As, Cd, Cu, Hg, Mn, Se, Zn),we found no significant intra-site differences ofcontaminant profiles for the two species. We pooledthe samples to examine inter-site differences andfound significant differences in contaminant profilesbetween shorebirds at the neighboring sites (P = 0.03). Shorebirds at Newark had higher (P < 0.05) concentrations of As, Cd, and Se than those at Hayward. Dowitchers at Newark had concentrations of Hg and Se which were highly correlated (P < 0.003) in a mean molar ratio of 1:19, similar tothat reported in other birds. In the larger dowitcherspecies, we also examined exposure to 20organochlorine compounds. Organic analyses showedthat the dowitchers had been exposed to DDE, PCBs,dieldrin and trans-nonachlor, but with no significantdifferences in concentrations between Hayward andNewark (P > 0.05).

Assessment of the potential of Allium sativum oil as a new medicament for non-vital pulpotomy of primary teeth.

PubMed

Mohammad, Shukry Gamal; Baroudi, Kusai

2015-01-01

The objective of this study was to compare the clinical and radiographic effects of Allium sativum oil and formocresol in nonvital pulpotomy in primary teeth. Twenty children ranging in age from 4 to 8 years were included in the study. In every one of those children, pulpotomy was indicated for the primary molars. Pulpotomy procedure was performed and the radicular pulp tissue of one molar was capped with A. sativum oil in a cotton pellet while the other molar was capped with formocresol. The teeth were evaluated clinically and radiographically before and after 6 months using standard clinical and radiographic criteria. Statistically, these results revealed significant difference between the radiographic findings of nonvital pulpotomy in primary molars with the two medicaments. Statistical analysis was performed using independent t-test and paired t-test at the significance level of α = 0.05. A. sativum oil has potent antibacterial properties that enable it to combat intracanal microbes in the infected pulp of primary molars. Better results were obtained when A. sativum oil was used. A. sativum oil had more powerful effects than formocresol on the infected pulp of primary nonvital molars.

Synthesis, characterization and optical studies of conjugated Schiff base polymer containing thieno[3,2-b]thiophene and 1,2,4-triazole groups

NASA Astrophysics Data System (ADS)

Cetin, Adnan; Korkmaz, Adem; Kaya, Esin

2018-02-01

A conjugated polyschiff base (poly(N-thieno[3,2-b]thiophen-2-yl)methylene)-1H-1,2,4-triazol-5-amine) poly(TTMA)) was synthesized by condensation polymerization between thieno[3,2-b]thiophene-2,5-dicarboxaldehyde and 3,5-diamino-1,2,4-triazole. The poly(TTMA) was characterized by FT-IR, 1H NMR, 13C NMR spectra and thermal analysis. The number average molecular weight (Mn) and polydispersity index of the poly(TTMA) were determined by gel permeation chromatography (GPC). In addition, the optical properties of the poly(TTMA) solutions were investigated at different molarities. The band gap Eg value of the poly(TTMA) decreased with the increasing molarity. The absorption band edge values of the poly(TTMA) decreased as the molarity increased. The average transmittance values of the poly(TTMA) increased with the increasing molarity and the highest values of molar extinction coefficient also were found in the near ultraviolet region. Its values decreased with the increasing molarity. These results showed that the poly(TTMA) can be used for the fabrication of many optoelectronic devices due to its suitable optical properties and low optical band gap.

A retrospective study of root canal therapy in non-vital primary molars.

PubMed

Stallaert, K M; Sigal, M J; Titley, K C; Andrews, P B

2016-12-01

This study was performed to assess the clinical and radiographic success rates of a formocresol and zinc oxide eugenol (ZOE) primary molar root canal therapy (RCT) technique. The effects of this treatment on the permanent successors and on exfoliation times were also investigated. Study design: the retrospective study included 161 patients with 211 primary molars treated by RCT by a single operator in a private paediatric dental office in the Toronto area. Data were coded and entered into a Microsoft Excel database and analysis undertaken using SPSS software. Predominantly non-parametric tests were used to evaluate statistical differences (p < 0.05). A clinical success rate of 90% (190/211) and a radiographic success rate of 77.3% (136/176) were obtained. Following RCT in a primary molar, enamel defects were found in 6.8% (7/103) of premolars, all of which occurred in first premolars, and in patients treated at a mean age of 54.1 months (p < 0.005). Treated molars exfoliated on average 7.6 months sooner than contralateral teeth (p < 0.005). This formocresol and ZOE RCT is a viable treatment for necrotic primary molars and yielded very high clinical and acceptable radiographic success rates.

Evaluation of the Root and Canal Morphology of Maxillary Permanent Molars and the Incidence of the Second Mesiobuccal Root Canal in Greek Population Using Cone-beam Computed Tomography

PubMed Central

Nikoloudaki, Georgia E.; Kontogiannis, Taxiarchis G.; Kerezoudis, Nikolaos P.

2015-01-01

Objectives: Cone-Beam Computed Tomography is an alternative imaging technique which has been recently introduced in the field of Oral & Maxillofacial Radiology. It has rapidly gained great popularity among clinicians due to its ability to detect lesions and defects of the orofacial region and provide three-dimensional information about them. In the field of Endodontics, CBCT can be a useful tool to reveal tooth morphology irregularities, additional root canals and vertical root fractures. The objective of this study is to evaluate the root and root canal morphology of the maxillary permanent molars in Greek population using Cone-Beam Computed Tomography. Materials and Methods : 273 cone-beam computed tomography (CBCT) images were examined. The number of roots and root canals of the first and second maxillary molars were evaluated. Root canal configuration was classified according to Weine’s classification by two independent examiners and statistical analysis was performed. Results : A total of 812 molars (410 first and 402 second ones) were evaluated. The vast majority of both first and second molars had three roots (89.26% and 85.07%, respectively). Most first molars had four canals, while most second molars had three. In the mesiobuccal roots, one foramen was recorded in 80.91% of all teeth. Other rare morphologic variations were also found, such as fusion of a maxillary second molar with a supernumerary tooth. Conclusion : Within the limitations of this study, it can be concluded that more attention should be given to the detection of additional canals during root canal treatment in maxillary permanent molars. Towards this effort, CBCT can provide the clinician with supplemental information about the different root canal configurations for successful Root Canal Treatment. PMID:26464594

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens.

PubMed

Kupczik, Kornelius; Hublin, Jean-Jacques

2010-11-01

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens. Copyright © 2010 Elsevier Ltd. All rights reserved.

Calcium and aluminum cycling in a temperate broadleaved deciduous forest of the eastern USA: relative impacts of tree species, canopy state, and flux type.

PubMed

Levia, Delphis F; Shiklomanov, Alexey N; Van Stan, John T; Scheick, Carrie E; Inamdar, Shreeram P; Mitchell, Myron J; McHale, Patrick J

2015-07-01

Ca/Al molar ratios are commonly used to assess the extent of aluminum stress in forests. This is among the first studies to quantify Ca/Al molar ratios for stemflow. Ca/Al molar ratios in bulk precipitation, throughfall, stemflow, litter leachate, near-trunk soil solution, and soil water were quantified for a deciduous forest in northeastern MD, USA. Data were collected over a 3-year period. The Ca/Al molar ratios in this study were above the threshold for aluminum stress (<1). Fagus grandifolia Ehrh. (American beech) had a median annual stemflow Ca/Al molar ratio of 15.7, with the leafed and leafless values of 12.4 and 19.2, respectively. The corresponding Ca/Al molar ratios for Liriodendron tulipifera L. (yellow poplar) were 11.9 at the annual time scale and 11.9 and 13.6 for leafed and leafless periods, respectively. Bayesian statistical analysis showed no significant effect of canopy state (leafed, leafless) on Ca/Al molar ratios. DOC was consistently an important predictor of calcium, aluminum, and Ca/Al ratios. pH was occasionally an important predictor of calcium and aluminum concentrations, but was not a good predictor of Ca/Al ratio in any of the best-fit models (of >500 examined). This study supplies new data on Ca/Al molar ratios for stemflow from two common deciduous tree species. Future work should examine Ca/Al molar ratios in stemflow of other species and examine both inorganic and organic aluminum species to better gauge the potential for, and understand the dynamics of, aluminum toxicity in the proximal area around tree boles.

Bivalent transition metal complexes of o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone: Spectroscopic, antibacterial, antifungal activity and thermogravimetric studies

NASA Astrophysics Data System (ADS)

Zaky, R. R.; Ibrahim, K. M.; Gabr, I. M.

2011-10-01

Schiff base complexes of Cu(II), Ni(II) and Zn(II) with the o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H 2o-HAHNH) containing N and O donor sites have been synthesized. Both ligand and its metal complexes were characterized by different physicochemical methods, elemental analysis, molar conductivity ( 1H NMR, 13C NMR, IR, UV-visible, ESR, MS spectra) and also thermal analysis (TG and DTG) techniques. The discussion of the outcome data of the prepared complexes indicates that the ligand behave as a bidentate and/or tridentate ligand. The electronic spectra of the complexes as well as their magnetic moments suggest octahedral geometries for all isolated complexes. The room temperature solid state ESR spectrum of the Cu(II) complex shows d x2- y2 as a ground state, suggesting tetragonally distorted octahedral geometry around Cu(II) centre. The molar conductance measurements proved that the complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E#, Δ H#, Δ G#, Δ S# are calculated from the DTG curves, for the [Ni(H O-HAHNH) 2] and [Zn(H 2 O-HAHNH)(OAc) 2]·H 2O complexes using the Coats-Redfern equation. Also, the antimicrobial properties of all compounds were studied using a wide spectrum of bacterial and fungal strains. The [Cu(H o-HAHNH)(OAc)(H 2O) 2] complex was the most active against all strains, including Aspergillus sp., Stemphylium sp. and Trichoderma sp. Fungi; E. coli and Clostridium sp. Bacteria.

Synthesis, spectral and theoretical studies of Ni(II), Pd(II) and Pt(II) complexes of 5-mercapto-1,2,4-triazole-3-imine-2'-hydroxynaphthaline.

PubMed

Gaber, Mohamed; El-Ghamry, Hoda; Atlam, Faten; Fathalla, Shaimaa

2015-02-25

Ni(II), Pd(II) and Pt(II) complexes of 5-mercapto-1,2,4-triazole-3-imine-2'-hydroxynaphthaline have been isolated and characterized by elemental analysis, IR, (1)H NMR, EI-mass, UV-vis, molar conductance, magnetic moment measurements and thermogravimetric analysis. The molar conductance values indicated that the complexes are non-electrolytes. The magnetic moment values of the complexes displayed diamagnetic behavior for Pd(II) and Pt(II) complexes and tetrahedral geometrical structure for Ni(II) complex. From the bioinorganic applications point of view, the interaction of the ligand and its metal complexes with CT-DNA was investigated using absorption and viscosity titration techniques. The Schiff-base ligand and its metal complexes have also been screened for their antimicrobial and antitumor activities. Also, theoretical investigation of molecular and electronic structures of the studied ligand and its metal complexes has been carried out. Molecular orbital calculations were performed using DFT (density functional theory) at B3LYP level with standard 6-31G(d,p) and LANL2DZ basis sets to access reliable results to the experimental values. The calculations were performed to obtain the optimized molecular geometry, charge density distribution, extent of distortion from regular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), Mulliken atomic charges, reactivity index (ΔE), dipole moment (D), global hardness (η), softness (σ), electrophilicity index (ω), chemical potential and Mulliken electronegativity (χ). Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of strontium addition and chitosan concentration variation on cytotoxicity of chitosan-alginate-carbonate apatite based bone scaffold

NASA Astrophysics Data System (ADS)

Perkasa, Rilis Eka; Umniati, B. Sri; Sunendar, Bambang

2017-09-01

Bone scaffold is one of the most important component in bone tissue engineering. Basically, bone scaffold is a biocompatible structure designed to replace broken bone tissue temporarily. Unlike conventional bone replacements, an advanced bone scaffold should be bioactive (e.g: supporting bone growth) and biodegradable as new bone tissue grow, while retain its mechanical properties similarity with bone. It is also possible to add more bioactive substrates to bone scaffold to further support its performance. One of the substrate is strontium, an element that could improve the ability of the bone to repair itself. However, it must be noted that excessive consumption of strontium could lead to toxicity and diseases, such as osteomalacia and hypocalcemia. This research aimed to investigate the effect of strontium addition to the cytotoxic property of chitosan-alginate-carbonate apatite bone scaffold. The amount of strontium added to the bone scaffold was 5% molar of the carbonate apatite content. As a control, bone scaffold without stronsium (0% molar) were also made. The effect of chitosan concentration variation on the cytotoxicity were also observed, where the concentration varies on 1% and 3% w/v of chitosan solution. The results showed an optimum result on bone scaffold sample with 5% molar of strontium and 3% chitosan, where 87.67% cells in the performed MTS-Assay cytotoxicity testing survived. This showed that the use of up to 5% molar addition of strontium and 3% chitosan could enhance the survivability of the cell.

Finite element stress analysis of stainless steel crowns.

PubMed

Prabhakar, Attiguppe R; Yavagal, Chandrashekar M; Chakraborty, Amrita; Sugandhan, S

2015-01-01

Though stainless steel crowns (SSCs) have often been stated as the best restorative modality, there are limited studies demonstrating its efficacy in restoring the functional integrity of the primary dentition. Hence has arisen, the necessity to establish the supremacy of SSCs. Evaluation of the efficacy of SSC to with stand compressive (0°), shearing (90°), and torsional (45°) stress when used as a restorative material. The study design employed four finite element models, each with differing amounts of tooth structure, which were exported to ANSYS software and subjected to an average simulated bite force of 245N. Four maxillary deciduous primary molars restored with SSCs (3M ESPE) were subjected to spiral computed tomography (CT) in order to obtain three-dimensional (3D) images, which were then converted into finite element models. They were each subjected to forces along the long axis of the tooth and at 45°and 90°. The maximal equivalent von Mises stress was demonstrated in the SSCs of all the models with only a minimal amount observed in the underlying dentine. In all situations, the maximal equivalent von Mises stress was well below the ultimate tensile strength values of stainless steel and dentine. Even at maximal physiologic masticatory force levels, a grossly destructed tooth restored with SSC is able to resist deformation.

Predicting bite force and cranial biomechanics in the largest fossil rodent using finite element analysis.

PubMed

Cox, Philip G; Rinderknecht, Andrés; Blanco, R Ernesto

2015-03-01

Josephoartigasia monesi, from the Pliocene of Uruguay, is the largest known fossil rodent, with an estimated body mass of 1000 kg. In this study, finite element analysis was used to estimate the maximum bite force that J. monesi could generate at the incisors and the cheek teeth. Owing to uncertainty in the model inputs, a sensitivity study was conducted in which the muscle forces and orientations were sequentially altered. This enabled conclusions to be drawn on the function of some of the masticatory muscles. It was found that J. monesi had a bite of 1389 N at the incisors, rising to 4165 N at the third molar. Varying muscle forces by 20% and orientations by 10° around the medio-lateral aspect led to an error in bite force of under 35% at each tooth. Predicted stresses across the skull were only minimally affected by changes to muscle forces and orientations, but revealed a reasonable safety factor in the strength of the skull. These results, combined with previous work, lead us to speculate that J. monesi was behaving in an elephant-like manner, using its incisors like tusks, and processing tough vegetation with large bite forces at the cheek teeth. © 2015 Anatomical Society.

Predicting bite force and cranial biomechanics in the largest fossil rodent using finite element analysis

PubMed Central

Cox, Philip G; Rinderknecht, Andrés; Blanco, R Ernesto

2015-01-01

Josephoartigasia monesi, from the Pliocene of Uruguay, is the largest known fossil rodent, with an estimated body mass of 1000 kg. In this study, finite element analysis was used to estimate the maximum bite force that J. monesi could generate at the incisors and the cheek teeth. Owing to uncertainty in the model inputs, a sensitivity study was conducted in which the muscle forces and orientations were sequentially altered. This enabled conclusions to be drawn on the function of some of the masticatory muscles. It was found that J. monesi had a bite of 1389 N at the incisors, rising to 4165 N at the third molar. Varying muscle forces by 20% and orientations by 10° around the medio-lateral aspect led to an error in bite force of under 35% at each tooth. Predicted stresses across the skull were only minimally affected by changes to muscle forces and orientations, but revealed a reasonable safety factor in the strength of the skull. These results, combined with previous work, lead us to speculate that J. monesi was behaving in an elephant-like manner, using its incisors like tusks, and processing tough vegetation with large bite forces at the cheek teeth. PMID:25652795

Polymeric material prepared from Schiff base based on O-carboxymethyl chitosan and its Cu(II) and Pd(II) complexes

NASA Astrophysics Data System (ADS)

Baran, Talat; Menteş, Ayfer

2016-07-01

In this study, a new eco-friendly Schiff base based on O-carboxymethyl chitosan ([OCMCS-7a]) and its copper(II) and palladium(II) complexes were synthesized. Characterizations of [OCMCS-7a] and its metal complexes were conducted using FTIR, 1H NMR, 13C NMR, TG/DTG, XRD, SEM-EDAX, ICP, UV-VIS, GC-MS, elemental analysis, magnetic moment and molar conductivity measurements. The degree of substitution (DS) of [OCMCS-7a] was determined by elemental analysis to be 0.44. It was shown by the solubility test that [OCMCS-7a] was completely soluble in water. Surface images of chitosan, [OCMCS-7a] and its Cu(II) and Pd(II) complexes were investigated using the SEM-EDAX technique. Their thermal behaviors and crystallinities of the synthesized complexes were determined by TG/DTG and X-ray powder diffraction techniques, respectively. The metal contents of the obtained complexes were determined using an ICP-OES instrument. From the analyses, it was noted that the thermal stabilities and crystallinities of [OCMCS-7a] and its complexes decreased compared to chitosan. As a consequence of surface screening, it was also noted that the surface structure of the chitosan was smoother than that of the obtained compounds.

Extraction, characterization and antioxidant activities of Se-enriched tea polysaccharides.

PubMed

Wang, Yuanfeng; Li, Yongfu; Liu, Yangyang; Chen, Xueqing; Wei, Xinlin

2015-01-01

Se-polysaccharides from Se-enriched tea leaves were purified by DEAE-sepharose fast flow gel column (2.5×60cm) and three polysaccharide fractions (Se-TPS1, Se-TPS2, and Se-TPS3) were isolated and purified with yields of 6.5, 37.14, and 8.57%, respectively. The average sizes of Se-TPS1 and Se-TPS2 were determined by HPGPC system, with molecular weights of 1.1×10(5) and 2.4×10(5)Da, respectively. Se-TPS3 was a polysaccharide polymer with two peaks with molecular weights of 9.2×10(5) and 2.5×10(5)Da. Monosaccharide components analysis by ion chromatography revealed Se-polysaccharides were acidic polysaccharoses and different from each other in monosaccharide kinds and molar ratio. Elements of Se, C, H, N, S, and 14 kinds of mineral elements were analyzed by AFS, EA, and ICP-AES, respectively. Spectral analysis (IR and UV) indicated Se-polysaccharides were typical glycoproteins. Morphological analyses of the samples were determined by SEM and AFM. In addition, the DPPH and superoxide radicals scavenging activities were also discussed to assess antioxidant activities of the samples, and Se-polysaccharides showed higher antioxidant activities compared to the ordinary polysaccharides. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of cyclical forces on the periodontal ligament and alveolar bone remodeling during orthodontic tooth movement

PubMed Central

Kalajzic, Zana; Peluso, Elizabeth Blake; Utreja, Achint; Dyment, Nathaniel; Nihara, Jun; Xu, Manshan; Chen, Jing; Uribe, Flavio; Wadhwa, Sunil

2014-01-01

Objective To investigate the effect of externally applied cyclical (vibratory) forces on the rate of tooth movement, the structural integrity of the periodontal ligament, and alveolar bone remodeling. Methods Twenty-six female Sprague-Dawley rats (7 weeks old) were divided into four groups: CTRL (unloaded), VBO (molars receiving a vibratory stimulus only), TMO (molars receiving an orthodontic spring only), and TMO+VB (molars receiving an orthodontic spring and the additional vibratory stimulus). In TMO and TMO+VB groups, the rat first molars were moved mesially for 2 weeks using Nickel-Titanium coil spring delivering 25 g of force. In VBO and TMO+VB groups, cyclical forces at 0.4 N and 30 Hz were applied occlusally twice a week for 10 minutes. Microfocus X-ray computed tomography analysis and tooth movement measurements were performed on the dissected rat maxillae. Tartrate-resistant acid phosphatase staining and collagen fiber assessment were performed on histological sections. Results Cyclical forces significantly inhibited the amount of tooth movement. Histological analysis showed marked disorganization of the collagen fibril structure of the periodontal ligament during tooth movement. Tooth movement caused a significant increase in osteoclast parameters on the compression side of alveolar bone and a significant decrease in bone volume fraction in the molar region compared to controls. Conclusions Tooth movement was significantly inhibited by application of cyclical forces. PMID:23937517

Impaction of lower third molars and their association with age: radiological perspectives.

PubMed

Ryalat, Soukaina; AlRyalat, Saif Aldeen; Kassob, Zaid; Hassona, Yazan; Al-Shayyab, Mohammad H; Sawair, Faleh

2018-04-04

Third molars are the most commonly impacted teeth, and their extraction is the most commonly performed procedure in oral and maxillofacial surgery. The aim of the present study is to describe the pattern of mandibular third molar impaction and to define the most appropriate age for prophylactic extraction of mandibular third molar teeth. A total of 1198 orthopantomographs (OPGs) with 1810 impacted lower third molars were reviewed by two authors. The pattern of eruption in relation to patient's age was examined using standard radiographic points and angles. Statistical analysis was performed using SPSS for Windows release 16.0 (SPSS Inc., Chicago, IL, USA). In patients older than 20 years, vertical pattern of impaction was the most common (21.4%); while in young patients; horizontal impaction was more common (21.3%). Furthermore, there was a constant pattern of increase in Pell-Gregory ramus class 1 with increasing age, as the prevalence of class 1 was 0% at age 18 years compared to 54.9% at the age of 26 years. Frequency of vertical impaction of lower third molars was seen more at an older age (> 20 years) in this study, with an increase in the retromolar space. Late extraction of mandibular third molar teeth (i.e. after the age of 20) is therefore recommended when prophylactic extraction is considered.

Prevalence of Extra Roots in Permanent Mandibular First Molars in Iranian Population: A CBCT Analysis

PubMed Central

Rahimi, Saeed; Mokhtari, Hadi; Ranjkesh, Bahram; Johari, Masoomeh; Frough Reyhani, Mohammad; Shahi, Shahriar; Seif Reyhani, Sina

2017-01-01

Introduction: Having knowledge about the anatomy of root canal system is essential for success of endodontic treatment. The present study used cone-beam computed tomography (CBCT), to evaluate the prevalence of third root in mandibular first molars in a selected Iranian population. Methods and Materials: A total of 386 CBCT images from subjects referred to oral and maxillofacial radiology department of dental faculty of Tabriz University of Medical Sciences from 2011 to 2013 were selected and evaluated for this study and the cases with well-developed permanent mandibular first molars were included. The 3D images were reconstructed in axial cross sections and evaluated by two endodontists for the presence of the third extra lingual (radix entomolaris) or buccal (radix paramolaris) root. The chi-squared test was used to evaluate the relationship between gender and bilateral incidence of extra roots in mandibular first molars. Results: The distribution of three-rooted mandibular first molars with an additional root was 3%, (3.53% in female and 2.50% in male patients). There was no significant relationship between gender and bilateral occurrence of three-rooted mandibular first molars. Conclusion: The occurrence of three-rooted mandibular first molars in Iranian population is not uncommon which should be taken into consideration by the dental practitioners during root canal treatment of these teeth. PMID:28179928

Molybdenum and copper in four varieties of common bean (Phaseolus vulgaris): new data of potential utility in designing healthy diet for diabetic patients.

PubMed

Ojeda, Armando Gómez; Wrobel, Kazimierz; Escobosa, Alma Rosa Corrales; Elguera, Julio César Torres; Garay-Sevilla, Ma Eugenia; Wrobel, Katarzyna

2015-02-01

Experimental evidence indicates that diabetic patients and individuals with impaired copper homeostasis could be at risk of molybdenum toxicity. A self-administered food frequency questionnaire revealed that in central Mexico, diabetic patients with severe complications tend to consume beans more often than individuals with less advanced disease. Four varieties of Phaseolus vulgaris were comparatively evaluated as the dietary sources of two elements; the results showed molybdenum concentration decreasing in the order peruvian > pinto > mayflower > black, whereas for copper, the order was peruvian > pinto ∼ black > mayflower. The two elements were determined in pre-soaking water, cooked legumes, and broth obtained in cooking procedure; an in vitro gut model was also applied to assess potentially bioavailable fraction of both elements in cooked beans. The results indicated that the black variety would be the healthiest bean choice for diabetic patients and individuals susceptible to Mo toxicity. Relatively low total molybdenum was found in this variety (2.9 ± 1.4 versus 4.3-10.9 μg g(-1) in other types), element availability was also low (15 % in supernatant from enzymolysis, 24.9 % in combined broth + supernatant fractions), and the molar ratio of Cu/Mo was the highest among four types (41, versus Cu/Mo <10 in peruvian, pinto, or mayflower). Considering peruvian and pinto beans, broth elimination would help to lower molybdenum intake with marginal effect on Cu/Mo molar ratio. This recommendation would be especially important for peruvian variety, which provided 1090, 803, and 197 μg day(-1) of molybdenum in raw grains, broth + supernatant, and supernatant, respectively (based on 100-g portion), exceeding the recommended daily allowance of 45 μg day(-1).

40 CFR Table A-7 to Subpart A of... - Data Elements That Are Inputs to Emission Equations and for Which the Reporting Deadline Is March...

Code of Federal Regulations, 2012 CFR

2012-07-01

... mass balance equation. K 98.116(b) Only annual production by product from each EAF (No CEMS). K 98.116... carbon content values, molecular weights for gaseous feedstocks, molecular weights for gaseous products... of gas flared, average molecular weight, carbon content of the flare, and molar volume conversion...

Genetic integration of molar cusp size variation in baboons

PubMed Central

Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T.; Fletcher, Zachary; Mahaney, Michael C.; Hlusko, Leslea J.

2010-01-01

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the non-occluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. PMID:20034010

Genetic integration of molar cusp size variation in baboons.

PubMed

Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T; Fletcher, Zachary; Mahaney, Michael C; Hlusko, Leslea J

2010-06-01

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the nonoccluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar. Copyright 2009 Wiley-Liss, Inc.

Possible effects of insulin-like growth factor-I, IGF-binding protein-3 and IGF-1/IGFBP-3 molar ratio on mammographic density: a cross-sectional study.

PubMed

Meggiorini, M L; Cipolla, V; Borgoni, G; Nofroni, I; Pala, A; de Felice, C

2012-01-01

The purpose of this study was to examine the possible effects of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio on mammographic density and assess whether this relationship was similar in subgroups of pre- and postmenopausal women. A group of 341 Italian women of childbearing age or naturally postmenopausal who had performed mammographic examination at the section of radiology of our department a maximum three months prior to recruitment were enrolled. A blood sample was drawn for determination of IGF-1, IGFBP-3 levels and IGF-1/IGFBP-3 molar ratio was calculated. On the basis of recent mammograms the women were divided into two groups: dense breast (DB) and non-dense breast (NDB). To assess the association between mammographic density and IGF-1, IGFBP-3 and Molar ratio Student's t-test was employed before and after stratified by menopausal status. The analysis of the relationship between mammographic density and plasma levels of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 molar ratio showed that IGF-1 levels and molar ratio varied in the two groups resulting in higher mean values in the DB group whereas IGFBP-3 showed similar values in both groups (DB and NDB). After stratification of the study population by menopausal status, no association was found. Our study provides strong evidence of a crude association between breast density, and plasma levels of IGF-1 and molar ratio. IGF-1 and molar ratio might increase mammographic density and thus the risk of developing breast cancer.

Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts

PubMed Central

Kim, Hang-Gul

2014-01-01

Objectives This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage. PMID:25551092

Does Simultaneous Third Molar Extraction Increase Intraoperative and Perioperative Complications in Orthognathic Surgery?

PubMed

Steinbacher, Derek M; Kontaxis, Katrina L

2016-06-01

Prior to orthognathic surgery, most surgeons recommend third molar extraction. Espoused reasons include potential risk for infection, untoward osteotomies, and worsened postoperative discomfort. However, in addition to being another procedure for the patient, this may necessitate a longer preorthognathic surgery phase. The purpose of this study is to compare the outcomes of orthognathic surgery with staged versus simultaneous third molar extractions. This was a retrospective analysis of patients who underwent orthognathic surgery from 2013 to 2014, with at least a 1-year follow-up period. Patients were stratified into 2 groups: Extraction of third molars at the time of surgery and prior extraction of third molars. Primary outcomes included the occurrence of unfavorable splits, infection, bleeding, malocclusion, and hardware failure. Secondary outcomes were procedure time, postoperative pain, and length of stay. Pearson χ tests and 2-tailed unpaired t tests were performed to determine if there was an association between the simultaneous removal of third molars and the primary and secondary outcome measures, respectively. One hundred patients were included in the study. Forty-nine patients had third molars extracted at the time of surgery and fifty-one did not. Complications included unfavorable split, postoperative infection, mild postoperative bleeding, postoperative malocclusion, and hardware failure. There was no significant difference in the incidence of complications in both groups. Procedure time was not considerably increased with extractions. There was no significant difference in postoperative pain or length of stay between both groups. Removing third molars concurrently with orthognathic surgery does not increase the risk of adverse outcomes, nor does it significantly influence hospital course.

Mechanical performance and thermal stability of glass fiber reinforced silica aerogel composites based on co-precursor method by freeze drying

NASA Astrophysics Data System (ADS)

Zhou, Ting; Cheng, Xudong; Pan, Yuelei; Li, Congcong; Gong, Lunlun; Zhang, Heping

2018-04-01

In order to maintain the integrity, glass fiber (GF) reinforced silica aerogel composites were synthesized using methltrimethoxysilane (MTMS) and water glass co-precursor by freeze drying method. The composites were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, uniaxial compressive test, three-point bending test, thermal conductivity analysis, contact angle test, TG-DSC analysis. It was found that the molar ratio of MTMS/water glass could significantly affect the properties of composites. The bulk density and thermal conductivity first decreased and then increased with the increasing molar ratio. The composites showed remarkable mechanical strength and flexibility compared with pure silica aerogel. Moreover, when the molar ratio is 1.8, the composites showed high specific surface area (870.9 m2/g), high contact angle (150°), great thermal stability (560 °C) and low thermal conductivity (0.0248 W/m·K). These outstanding properties indicate that GF/aerogels have broad prospects in the field of thermal insulation.

Spectroscopic studies and thermal analysis of mononuclear metal complexes with moxifloxacin and 2,2‧-bipyridine and their effects on acute lung injury induced by hydrochloric acid in rats

NASA Astrophysics Data System (ADS)

El-Hamid, S. M. Abd; El-Demerdash, R. S.; Arafat, H. F. H.; Sadeek, S. A.

2017-12-01

The article describes the interaction of Y(III), Zr(IV), La(III), Ce(IV) and U(VI) with moxifloxacin hydrochloride and 2,2‧-bipyridine. Characterization of complexes was made by elemental analyses, molar conductivity, magnetic moment measurements and spectral measurements e.g. IR, UV-Vis., 1H NMR and mass as well as thermal analyses (TG and DTG). The molar conductivity shows that the complexes are electrolytes nature. Spectroscopic investigation of the solid complexes studied here indicate that moxifloxacin hydrochloride and 2,2‧-bipyridine are coordinated to the metal ions in a neutral bidentate manner. After complete characterization, the chemical formulae of the complexes were established. The calculated bond length and force constant, F(Udbnd O), in the uranyl complex are 1.756 Å and 637.90 Nm-1, respectively. Kinetic and thermodynamic parameters were determined using Coats-Redfern and Horowitz-Metzger equations. Establishment of hydrochloric acid that induce acute lung injury (ALI) in rats by intratracheal administration through damaging the alveolar epithelium and activation of the neutrophil and subsequent oxidative stress by increasing malondialdehyde (MDA), tumor necrosis factor (TNF-α) and neutrophil, which were confirmed by histopathological investigation while decreasing in antioxidant enzymes and lymphocytes. Whereas treatment with mixed-ligand metal complexes significantly decrease MDA, TNF-α and neutrophils and increase antioxidant and lymphocytes.

Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: synthesis, characterization, fluorescence and corrosion inhibitors of ligands.

PubMed

Ali, Omyma A M

2014-11-11

Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans. Copyright © 2014 Elsevier B.V. All rights reserved.

Finite Element Analysis of IPS Empress II Ceramic Bridge Reinforced by Zirconia Bar

PubMed Central

Kermanshah, H.; Bitaraf, T.; Geramy, A.

2012-01-01

Objective: The aim of this study was to determine the effect of trenched zirconia bar on the von Mises stress distribution of IPS –Empress II core ceramics. Materials and Methods: The three-dimensional model including a three-unit bridge from the second premolar to the second molar was designed. The model was reinforced with zirconia bar (ZB), zirconia bar with vertical trench (VZB) and zirconia bar with horizontal trench (HZB) (cross sections of these bars were circular). The model without zirconia bar was designed as the control. The bridges were loaded by 200 N and 500 N on the occlusal surface at the middle of the pontic component and von Mises stresses were evaluated along a defined path. Results: In the connector area, von Mises stress in MPa were approximately identical in the specimens with ZB (at molar connector (MC): 4.75 and at premolar connector (PC): 6.40) and without ZB (MC: 5.50, PC: 6.68), and considerable differences were not recognized. Whereas, Von-Mises stress (MPa) in the specimens with horizontal trenched Zirconia bar (HZB) (MC: 3.91, PC: 2.44) and Vertical trenched Zirconia bar (VZB) (MC: 2.53, PC: 2.56) was decreased considerably. Conclusion: Embeded trenched zirconia bar could reinforce IPS-Empress II at the connector area which is a main failure region in all ceramic fixed partial dentures. PMID:23323181

Finite Element Analysis of IPS Empress II Ceramic Bridge Reinforced by Zirconia Bar.

PubMed

Kermanshah, H; Bitaraf, T; Geramy, A

2012-01-01

The aim of this study was to determine the effect of trenched zirconia bar on the von Mises stress distribution of IPS -Empress II core ceramics. The three-dimensional model including a three-unit bridge from the second premolar to the second molar was designed. The model was reinforced with zirconia bar (ZB), zirconia bar with vertical trench (VZB) and zirconia bar with horizontal trench (HZB) (cross sections of these bars were circular). The model without zirconia bar was designed as the control. The bridges were loaded by 200 N and 500 N on the occlusal surface at the middle of the pontic component and von Mises stresses were evaluated along a defined path. IN THE CONNECTOR AREA, VON MISES STRESS IN MPA WERE APPROXIMATELY IDENTICAL IN THE SPECIMENS WITH ZB (AT MOLAR CONNECTOR (MC): 4.75 and at premolar connector (PC): 6.40) and without ZB (MC: 5.50, PC: 6.68), and considerable differences were not recognized. Whereas, Von-Mises stress (MPa) in the specimens with horizontal trenched Zirconia bar (HZB) (MC: 3.91, PC: 2.44) and Vertical trenched Zirconia bar (VZB) (MC: 2.53, PC: 2.56) was decreased considerably. Embeded trenched zirconia bar could reinforce IPS-Empress II at the connector area which is a main failure region in all ceramic fixed partial dentures.

A sodium–aluminum hybrid battery

DOE PAGES

Sun, Xiao-Guang; Zhang, Zhizhen; Guan, Hong Yu; ...

2017-03-07

We present novel hybrid batteries that are fabricated using an aluminum anode, a sodium intercalation cathode Na 3V 2(PO 4) 3 (NVP), and a sodium/aluminum dual salt electrolyte based on NaAlCl 4 and an eutectic mixture of 1-ethyl-3-methylimidazolium chloride (EMImC) and aluminum chloride. Cyclic voltammograms indicate that increasing the molar concentration of AlCl 3 in the electrolyte is beneficial to high coulombic efficiency of aluminum deposition/stripping, which, unfortunately, results in lower coulombic efficiency of sodium extraction/insertion in the cathode. Therefore, EMImC–AlCl 3 with a molar ratio of 1–1.1 is used for battery evaluation. The hybrid battery with 1.0 M NaAlClmore » 4 exhibits a discharge voltage of 1.25 V and a cathodic capacity of 99 mA h g -1 at a current rate of C/10. In addition, the hybrid battery exhibits good rate performance and long-term cycling stability while maintaining a high coulombic efficiency of 98%. It is also demonstrated that increasing salt concentration can further enhance the cycling performance of the hybrid battery. X-ray diffraction analysis of the NVP electrodes under different conditions confirms that the main cathode reaction is indeed Na extraction/insertion. Based on all earth-abundant elements, the new Na–Al hybrid battery is very attractive for stationary and grid energy storage applications.« less

A sodium–aluminum hybrid battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao-Guang; Zhang, Zhizhen; Guan, Hong Yu

We present novel hybrid batteries that are fabricated using an aluminum anode, a sodium intercalation cathode Na 3V 2(PO 4) 3 (NVP), and a sodium/aluminum dual salt electrolyte based on NaAlCl 4 and an eutectic mixture of 1-ethyl-3-methylimidazolium chloride (EMImC) and aluminum chloride. Cyclic voltammograms indicate that increasing the molar concentration of AlCl 3 in the electrolyte is beneficial to high coulombic efficiency of aluminum deposition/stripping, which, unfortunately, results in lower coulombic efficiency of sodium extraction/insertion in the cathode. Therefore, EMImC–AlCl 3 with a molar ratio of 1–1.1 is used for battery evaluation. The hybrid battery with 1.0 M NaAlClmore » 4 exhibits a discharge voltage of 1.25 V and a cathodic capacity of 99 mA h g -1 at a current rate of C/10. In addition, the hybrid battery exhibits good rate performance and long-term cycling stability while maintaining a high coulombic efficiency of 98%. It is also demonstrated that increasing salt concentration can further enhance the cycling performance of the hybrid battery. X-ray diffraction analysis of the NVP electrodes under different conditions confirms that the main cathode reaction is indeed Na extraction/insertion. Based on all earth-abundant elements, the new Na–Al hybrid battery is very attractive for stationary and grid energy storage applications.« less

Third molar development by measurements of open apices in an Italian sample of living subjects.

PubMed

De Luca, Stefano; Pacifici, Andrea; Pacifici, Luciano; Polimeni, Antonella; Fischetto, Sara Giulia; Velandia Palacio, Luz Andrea; Vanin, Stefano; Cameriere, Roberto

2016-02-01

The aim of this study is to analyse the age-predicting performance of third molar index (I3M) in dental age estimation. A multiple regression analysis was developed with chronological age as the independent variable. In order to investigate the relationship between the I3M and chronological age, the standard deviation and relative error were examined. Digitalized orthopantomographs (OPTs) of 975 Italian healthy subjects (531 female and 444 male), aged between 9 and 22 years, were studied. Third molar development was determined according to Cameriere et al. (2008). Analysis of covariance (ANCOVA) was applied to study the interaction between I3M and the gender. The difference between age and third molar index (I3M) was tested with Pearson's correlation coefficient. The I3M, the age and the gender of the subjects were used as predictive variable for age estimation. The small F-value for the gender (F = 0.042, p = 0.837) reveals that this factor does not affect the growth of the third molar. Adjusted R(2) (AdjR(2)) was used as parameter to define the best fitting function. All the regression models (linear, exponential, and polynomial) showed a similar AdjR(2). The polynomial (2nd order) fitting explains about the 78% of the total variance and do not add any relevant clinical information to the age estimation process from the third molar. The standard deviation and relative error increase with the age. The I3M has its minimum in the younger group of studied individuals and its maximum in the oldest ones, indicating that its precision and reliability decrease with the age. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Clinical and radiographic success of mineral trioxide aggregate compared with formocresol as a pulpotomy treatment in primary molars: a systematic review and meta-analysis.

PubMed

Marghalani, Abdullah A; Omar, Samah; Chen, Jung-Wei

2014-07-01

The authors conducted a systematic review and meta-analysis to compare the long-term clinical and radiographic success of using mineral trioxide aggregate (MTA) and formocresol (FC) as a pulp-dressing material in pulpotomy treatment in primary molars. The authors searched MEDLINE, Thomson Reuters Web of Science and the Cochrane Central Register of Controlled Trials for randomized controlled trials (RCTs) published from Jan. 1, 1990, to May 9, 2013. For an RCT to be included, the authors required that the primary molars treated with a pulpotomy procedure must have received stainless steel crowns as a final restoration and that rubber dam isolation was used during treatment; that the pulp must have been vital as determined clinically by means of hemorrhage control with a cotton pellet; and that the RCT must have included a follow-up period of at least two years. For each included RCT, two authors assessed the risk of bias independently. The authors identified 20 trials and included five of them. A total of 377 primary molars were treated. The authors judged that none of the included RCTs had a low risk of bias. They noted no significant differences in clinical success (relative risk [RR] = 1.01; 95 percent confidence interval [CI], 0.98-1.05) and radiographic success (RR = 1.09; 95 percent CI, 0.97-1.21) for primary molars treated with MTA versus those treated with FC. On the basis of the limited evidence, pulpotomy procedures performed in primary molars involving the use of MTA or FC showed comparable clinical success rates.

Odontometric analysis of permanent maxillary first molar in gender determination.

PubMed

Shireen, Ayesha; Ara, Syeda Arshiya

2016-01-01

This study was conducted to assess the sex determination potential from mesiodistal (MD) and buccolingual (BL) dimensions of permanent maxillary first molar. The study was conducted in the Department of Oral Medicine and Radiology, Al-Badar Rural Dental College and Hospital, Gulbarga, Karnataka, on 600 subjects (300 male and 300 female), aged 17-25 years. The subjects were selected based on the inclusion and exclusion criteria set forth for the study. After obtaining informed consent, the intraoral measurements of MD and BL dimensions on casts of the first maxillary molars were taken using digital vernier caliper with resolution of 0.01 mm. The data obtained were subjected to statistical analysis using paired and unpaired t -test to compare MD and BL dimensions between males and females. P ≤0.05 was considered statistically significant. The mean MD width of the first maxillary molar was 10.60 ± 0.6644 mm (right) and 10.60 ± 0.6644 mm (left) in males and 10.40 ± 0.6255 mm (right) and 10.40 ± 0.6255 mm (left) in females. The mean BL width of the first maxillary molar was 11.60 ± 1.2227 mm (right) and 11.60 ± 1.2227 mm (left) in males and 11.20 ± 0.8440 mm (right) and 11.20 ± 0.8440 mm (left) in females. The differences between males and females in MD and BL dimensions measured were statistically significant ( P < 0.05). Right and left MD dimensions exhibited sexual dimorphism of 1.92% and right and left BL dimensions exhibited sexual dimorphism of 3.57%. The MD and BL dimensions of the maxillary first molars may be used as an aid in sex discrimination.

Effect of Intraoral Aging on Debris Accumulation and Friction of First Molar Tubes.

PubMed

Chaptini, Edmond; Khoury, Elie; Cacciafesta, Vittorio; Naaman, Nada

2016-11-01

The aim of this article was to evaluate the impact of intraoral aging and site specificity on debris accumulation and friction in molar tubes after intraoral use. A total of 80 intraorally used first molar convertible tubes were provided by 20 orthodontic adolescent patients after 6 months of treatment. The specimens were divided into eight groups (n = 10) according to the mouth quadrant and the type of examination [four groups of ten tubes for scanning electron microscope (SEM) and four groups of ten tubes for friction test]. Scanning electron microscope examination was performed after opening the convertible caps and friction test was executed using a 0.019'' × 0.025'' stainless steel wire, which was inserted in the tubes belonging to each group. The Mann-Whitney test, analysis of variance (ANOVA), and Bonferroni tests were performed for statistical analysis at 0.01 level of significance. There was a significant increase in the amount of debris and frictional force after 6 months of intraoral exposure (p < 0.0001). Debris scores were higher (10% increase) on the upper tubes when compared with the lower ones, with no statistical difference. Mean frictional force ranged from 0.22 to 0.26 N according to the mouth quadrant, but the difference between groups was also not significant. After 6 months of intraoral exposure, there was a significant increase in the amount of debris in the first molar tube slots, leading to significantly higher frictional forces during sliding mechanics. The influence of site specificity on the amount of debris and on frictional forces of the first molar tubes could not be demonstrated. Molar tubes should be cleaned, before and during sliding mechanics, in order to minimize friction.

Correlative bacteriologic and micro-computed tomographic analysis of mandibular molar mesial canals prepared by self-adjusting file, reciproc, and twisted file systems.

PubMed

Siqueira, José F; Alves, Flávio R F; Versiani, Marco A; Rôças, Isabela N; Almeida, Bernardo M; Neves, Mônica A S; Sousa-Neto, Manoel D

2013-08-01

This ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative bacteriologic and micro-computed tomographic (μμCT) analysis. The mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File [ReDent-Nova, Ra'anana, Israel], Reciproc [VDW, Munich, Germany], and Twisted File [SybronEndo, Orange, CA]). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals. All instrumentation protocols promoted a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups (P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area (P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters (P > .05). The 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effect of oral contraceptive use on the incidence of dry socket in females following impacted mandibular third molar extraction: a meta-analysis.

PubMed

Xu, J-L; Sun, L; Liu, C; Sun, Z-H; Min, X; Xia, R

2015-09-01

The aim of this comprehensive meta-analysis was to provide evidence-based data to test whether oral contraceptive (OC) use can promote the incidence of dry socket (DS) in females following impacted mandibular third molar extraction. PubMed, the Cochrane Library, and Elsevier Science Direct databases were searched. The pooled risk ratio (RR) with 95% confidence interval (CI) was calculated using fixed-effects or random-effects model analysis. Heterogeneity among studies was evaluated with the Cochran test and I(2) statistic. Study quality was assessed with the Newcastle-Ottawa scale. Of 70 articles identified in the search, 12 reporting 16 clinical controlled trials were included in this study. The incidence of DS was significantly greater in the OC groups than in the control groups (RR 1.80, 95% CI 1.33-2.43). Subgroup analyses showed that the unit assessed (tooth or patient), the region in which the study was conducted, and the intervention were not related to the incidence of DS in females taking OC after impacted mandibular third molar extraction. The sensitivity analysis showed no significant change when any one study was excluded. Publication bias was also not detected. This study suggests that OC use may promote the incidence of DS in females following impacted mandibular third molar extraction. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Does the piezoelectric surgical technique produce fewer postoperative sequelae after lower third molar surgery than conventional rotary instruments? A systematic review and meta analysis.

PubMed

Al-Moraissi, E A; Elmansi, Y A; Al-Sharaee, Y A; Alrmali, A E; Alkhutari, A S

2016-03-01

A systematic review and meta-analysis was conducted to answer the clinical question "Does the piezoelectric surgical technique produce fewer postoperative sequelae after lower third molar surgery than conventional rotary instruments?" A systematic and electronic search of several databases with specific key words, a reference search, and a manual search were performed from respective dates of inception through November 2014. The inclusion criteria were clinical human studies, including randomized controlled trials (RCTs), controlled clinical trials (CCTs), and retrospective studies, with the aim of comparing the piezoelectric surgical osteotomy technique to the standard rotary instrument technique in lower third molar surgery. Postoperative sequelae (oedema, trismus, and pain), the total number of analgesics taken, and the duration of surgery were analyzed. A total of nine articles were included, six RCTs, two CCTs, and one retrospective study. Six studies had a low risk of bias and three had a moderate risk of bias. A statistically significant difference was found between piezoelectric surgery and conventional rotary instrument surgery for lower third molar extraction with regard to postoperative sequelae (oedema, trismus, and pain) and the total number of analgesics taken (P=0.0001, P=0.0001, P<0.00001, and P<0.0001, respectively). However, a statistically significant increased surgery time was required in the piezoelectric osteotomy group (P<0.00001). The results of the meta-analysis showed that piezoelectric surgery significantly reduced the occurrence of postoperative sequelae (oedema, trismus, and pain) and the total number of analgesics taken compared to the conventional rotary instrument technique in lower third molar surgery, but required a longer surgery time. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Trace elements in oceanic pelagic communities in the western Indian Ocean.

PubMed

Bodin, Nathalie; Lesperance, Dora; Albert, Rona; Hollanda, Stephanie; Michaud, Philippe; Degroote, Maxime; Churlaud, Carine; Bustamante, Paco

2017-05-01

The mineral composition of target and non-target pelagic fish caught by purse-seiners and longliners in the western-central Indian Ocean was determined. From the 10 essential elements analysed, selenium and zinc showed the highest concentrations in swordfish and blue marlin while Indian mackerel appeared as a good source of copper, iron and chrome. All catch had levels of lead and cadmium, two toxic elements, below the maximum sanitary limits. Although some concerns were raised regarding mercury concentrations in the largest species (wahoo, swordfish and blue marlin), molar ratios of mercury and selenium indicate that all oceanic pelagic fish from the western-central Indian Ocean are safe for human consumption. This study also gives insights on the relationships between the levels of essential and toxic elements in fish muscle and the size, trophic position and diet sources of the studied pelagic species. Copyright © 2017 Elsevier Ltd. All rights reserved.

First finding of a mammoth female ( Mammuthus primigenius Blum.) on the Taimyr Peninsula

NASA Astrophysics Data System (ADS)

Kirillova, I. V.; Shidlovskiy, F. K.; Khasanov, B. F.

2011-02-01

The first finding of a mammoth female skeleton from the Kastykhtakh River valley, Taimyr Peninsula, is described. The skeleton consists of 104 elements including the skull and lower jaw; small distal limb bones, tail vertebrae, and one tusk are absent. There are teeth of the two last changes in the jaws. The skeleton elements have individual features: sigmoid contact of the low second and third molars, crack in the neural arch of the atlas, and false joint and calluses on places of the rib fractures. The calibrated radiocarbon dating of the tubular bone is 32 070-30 565 yr (Kargin interglacial time).

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body.

PubMed

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification.

Spectral and thermal studies with anti-fungal aspects of some organotin(IV) complexes with nitrogen and sulphur donor ligands derived from 2-phenylethylamine

NASA Astrophysics Data System (ADS)

Singh, Rajeev; Kaushik, N. K.

2008-11-01

Some complexes of 2-phenylethyl dithiocarbamate, thiohydrazides and thiodiamines with dibenzyltin(IV) chloride, tribenzyltin(IV) chloride and di( para-chlorobenzyl)tin(IV) dichloride have been synthesized and investigated in 1:2 and 1:1 molar ratio. The dithiocarbamate ligand act as monoanionic bidentate and thiohydrazide, thiodiamines act as neutral bidentate ligand. The synthesized complexes have been characterized by elemental analysis and molecular weight determination studies and their bonding pattern suggested on the basis of electronic, infrared, 1H and 13C NMR spectroscopy. Using thermogravimetric (TG) and differential thermal analysis (DTA) various thermodynamic and kinetic parameters viz. reaction order ( n), apparent activation energy ( Ea), apparent activation entropy ( S#) and heat of reaction (Δ H) have been calculated and correlated with the structural aspects for solid-state decomposition of complexes. The ligands and their tin complexes have also been screened for their fungitoxicity activity against Rhizoctonia solanii and Sclerotium rolfsii and their ED 50 values calculated.

Spectral and thermal studies with anti-fungal aspects of some organotin(IV) complexes with nitrogen and sulphur donor ligands derived from 2-phenylethylamine.

PubMed

Singh, Rajeev; Kaushik, N K

2008-11-15

Some complexes of 2-phenylethyl dithiocarbamate, thiohydrazides and thiodiamines with dibenzyltin(IV) chloride, tribenzyltin(IV) chloride and di(para-chlorobenzyl)tin(IV) dichloride have been synthesized and investigated in 1:2 and 1:1 molar ratio. The dithiocarbamate ligand act as monoanionic bidentate and thiohydrazide, thiodiamines act as neutral bidentate ligand. The synthesized complexes have been characterized by elemental analysis and molecular weight determination studies and their bonding pattern suggested on the basis of electronic, infrared, 1H and 13C NMR spectroscopy. Using thermogravimetric (TG) and differential thermal analysis (DTA) various thermodynamic and kinetic parameters viz. reaction order (n), apparent activation energy (Ea), apparent activation entropy (S#) and heat of reaction (DeltaH) have been calculated and correlated with the structural aspects for solid-state decomposition of complexes. The ligands and their tin complexes have also been screened for their fungitoxicity activity against Rhizoctonia solanii and Sclerotium rolfsii and their ED50 values calculated.

Synthesis, spectral, thermal and antimicrobial studies of transition metal complexes of 14-membered tetraaza[N4] macrocyclic ligand

NASA Astrophysics Data System (ADS)

Shankarwar, Sunil G.; Nagolkar, Bhagwat B.; Shelke, Vinod A.; Chondhekar, Trimbak K.

2015-06-01

A series of metal complexes of Mn(II), Co(II), Ni(II), Cu(II), have been synthesized with newly synthesized biologically active macrocyclic ligand. The ligand was synthesized by condensation of β-diketone 1-(4-chlorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione and o-phenylene diamine. All the complexes were characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV-Vis spectroscopy and mass spectroscopy. From the analytical data, stoichiometry of the complexes was found to be 1:2 (metal:ligand). Thermal behavior (TG/DTA) and kinetic parameters suggest more ordered activated state in complex formation. All the complexes are of high spin type and six coordinated. On the basis of IR, electronic spectral studies and magnetic behavior, an octahedral geometry has been assigned to these complexes. The antibacterial and antifungal activities of the ligand and its metal complexes, has been screened in vitro against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma respectively.

Assessment of the potential of Allium sativum oil as a new medicament for non-vital pulpotomy of primary teeth

PubMed Central

Mohammad, Shukry Gamal; Baroudi, Kusai

2015-01-01

Objective: The objective of this study was to compare the clinical and radiographic effects of Allium sativum oil and formocresol in nonvital pulpotomy in primary teeth. Materials and Methods: Twenty children ranging in age from 4 to 8 years were included in the study. In every one of those children, pulpotomy was indicated for the primary molars. Pulpotomy procedure was performed and the radicular pulp tissue of one molar was capped with A. sativum oil in a cotton pellet while the other molar was capped with formocresol. The teeth were evaluated clinically and radiographically before and after 6 months using standard clinical and radiographic criteria. Statistically, these results revealed significant difference between the radiographic findings of nonvital pulpotomy in primary molars with the two medicaments. Statistical analysis was performed using independent t-test and paired t-test at the significance level of α = 0.05. Results: A. sativum oil has potent antibacterial properties that enable it to combat intracanal microbes in the infected pulp of primary molars. Better results were obtained when A. sativum oil was used. Conclusion: A. sativum oil had more powerful effects than formocresol on the infected pulp of primary nonvital molars. PMID:26312232

Optimization of lipase-catalyzed biodiesel by isopropanolysis in a continuous packed-bed reactor using response surface methodology.

PubMed

Chang, Cheng; Chen, Jiann-Hwa; Chang, Chieh-Ming J; Wu, Tsung-Ta; Shieh, Chwen-Jen

2009-10-31

Isopropanolysis reactions were performed using triglycerides with immobilized lipase in a solvent-free environment. This study modeled the degree of isopropanolysis of soybean oil in a continuous packed-bed reactor when Novozym 435 was used as the biocatalyst. Response surface methodology (RSM) and three-level-three-factor Box-Behnken design were employed to evaluate the effects of synthesis parameters, reaction temperature ( degrees C), flow rate (mL/min) and substrate molar ratio of isopropanol to soybean oil, on the percentage molar conversion of biodiesel by transesterification. The results show that flow rate and temperature have a significant effect on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were as follows: flow rate 0.1 mL/min, temperature 51.5 degrees C and substrate molar ratio 1:4.14. The predicted value was 76.62+/-1.52% and actual experimental value was 75.62+/-0.81% molar conversion. Moreover, continuous enzymatic process for seven days did not show any appreciable decrease in the percent of molar conversion (75%). This work demonstrates the applicability of lipase catalysis to prepare isopropyl esters by transesterification in solvent-free system with a continuous packed-bed reactor for industrial production.

A series of novel oxovanadium(IV) complexes: Synthesis, spectral characterization and antimicrobial study

NASA Astrophysics Data System (ADS)

Sahani, M. K.; Pandey, S. K.; Pandey, O. P.; Sengupta, S. K.

2014-09-01

Oxovanadium(IV) complexes have been synthesized by reacting vanadyl sulfate with Schiff bases derived from 4-amino-5-(substitutedphenoxyacetic acid)-1,2,4-triazole-3-thiol and benzil. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non-electrolytes and characterized by elemental analysis, spectral techniques (UV-Vis, IR, EPR and XRD) and magnetic moment measurements. The EPR spectra indicate that the free electron is in dxy orbital. In vitro antifungal activity of ligands and synthesized compounds was determined against fungi Aspergillus niger, Colletotrichum falcatum and Colletotrichum pallescence and in vitro antibacterial activity was determined by screening the compounds against Gram-negative (Escherichia coli and Salmonella typhi) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacterial strains. The antimicrobial activities have shown that the activity increases upon complexation.

Spectroscopic studies on two mono nuclear iron (III) complexes derived from a schiff base and an azodye

NASA Astrophysics Data System (ADS)

Mini, S.; Sadasivan, V.; Meena, S. S.; Bhatt, Pramod

2014-10-01

Two new mono nuclear Fe(III) complexes of an azodye (ANSN) and a Schiff base (FAHP) are reported. The azodye is prepared by coupling diazotized 1-amino-2-naphthol-4-sulphonicacid with 2-naphthol and the Schiff base is prepared by condensing 2-amino-3-hydroxy pyridine with furfural. The complexes were synthesized by the reaction of FeCl3˙2H2O with respective ligands. They were characterized on the basis of elemental analysis and spectral studies like IR, NMR, Electronic and M.ssbauer. Magnetic susceptibility and Molar conductance of complexes at room temperature were studied. Based on the spectroscopic evidences and other analytical data the complexes are formulated as[Fe(ANSN)Cl(H2O)2] and [Fe(FAHP)Cl2(H2O)2].

Analysis of the internal anatomy of maxillary first molars by using different methods.

PubMed

Baratto Filho, Flares; Zaitter, Suellen; Haragushiku, Gisele Aihara; de Campos, Edson Alves; Abuabara, Allan; Correr, Gisele Maria

2009-03-01

The success of endodontic treatment depends on the identification of all root canals so that they can be cleaned, shaped, and obturated. This study investigated internal morphology of maxillary first molars by 3 different methods: ex vivo, clinical, and cone beam computed tomography (CBCT) analysis. In all these different methods, the number of additional root canals and their locations, the number of foramina, and the frequency of canals that could or could not be negotiated were recorded. In the ex vivo study, 140 extracted maxillary first molars were evaluated. After canals were accessed and detected by using an operating microscope, the teeth with significant anatomic variances were cleared. In the clinical analysis, the records of 291 patients who had undergone endodontic treatment in a dental school during a 2-year period were used. In the CBCT analysis, 54 maxillary first molars were evaluated. The ex vivo assessment results showed a fourth canal frequency in 67.14% of the teeth, besides a tooth with 7 root canals (0.72%). Additional root canals were located in the mesiobuccal root in 92.85% of the teeth (17.35% could not be negotiated), and when they were present, 65.30% exhibited 1 foramen. Clinical assessment showed that 53.26%, 0.35%, and 0.35% of the teeth exhibited 4, 5, and 6 root canals, respectively. Additional root canals were located in this assessment in mesiobuccal root in 95.63% (27.50% could not be negotiated), and when they were present, 59.38% exhibited 1 foramen. CBCT results showed 2, 4, and 5 root canals in 1.85%, 37.05%, and 1.85% of the teeth, respectively. When present, additional canals showed 1 foramen in 90.90% of the teeth studied. This study demonstrated that operating microscope and CBCT have been important for locating and identifying root canals, and CBCT can be used as a good method for initial identification of maxillary first molar internal morphology.

Influence of maxillary posterior discrepancy on upper molar vertical position and facial vertical dimensions in subjects with or without skeletal open bite

PubMed Central

Aliaga-Del Castillo, Aron; Pérez-Vargas, Luis Fernando; Flores-Mir, Carlos

2016-01-01

Summary Objectives: To determine the influence of maxillary posterior discrepancy on upper molar vertical position and dentofacial vertical dimensions in individuals with or without skeletal open bite (SOB). Materials and methods: Pre-treatment lateral cephalograms of 139 young adults were examined. The sample was divided into eight groups categorized according to their sagittal and vertical skeletal facial growth pattern and maxillary posterior discrepancy (present or absent). Upper molar vertical position, overbite, lower anterior facial height and facial height ratio were measured. Independent t-test was performed to determine differences between the groups considering maxillary posterior discrepancy. Principal component analysis and MANCOVA test were also used. Results: No statistically significant differences were found comparing the molar vertical position according to maxillary posterior discrepancy for the SOB Class I group or the group with adequate overbite. Significant differences were found in SOB Class II and Class III groups. In addition, an increased molar vertical position was found in the group without posterior discrepancy. Limitations: Some variables closely related with the individual’s intrinsic craniofacial development that could influence the evaluated vertical measurements were not considered. Conclusions and implications: Overall maxillary posterior discrepancy does not appear to have a clear impact on upper molar vertical position or facial vertical dimensions. Only the SOB Class III group without posterior discrepancy had a significant increased upper molar vertical position. PMID:26385786

Influence of maxillary posterior discrepancy on upper molar vertical position and facial vertical dimensions in subjects with or without skeletal open bite.

PubMed

Arriola-Guillén, Luis Ernesto; Aliaga-Del Castillo, Aron; Pérez-Vargas, Luis Fernando; Flores-Mir, Carlos

2016-06-01

To determine the influence of maxillary posterior discrepancy on upper molar vertical position and dentofacial vertical dimensions in individuals with or without skeletal open bite (SOB). Pre-treatment lateral cephalograms of 139 young adults were examined. The sample was divided into eight groups categorized according to their sagittal and vertical skeletal facial growth pattern and maxillary posterior discrepancy (present or absent). Upper molar vertical position, overbite, lower anterior facial height and facial height ratio were measured. Independent t-test was performed to determine differences between the groups considering maxillary posterior discrepancy. Principal component analysis and MANCOVA test were also used. No statistically significant differences were found comparing the molar vertical position according to maxillary posterior discrepancy for the SOB Class I group or the group with adequate overbite. Significant differences were found in SOB Class II and Class III groups. In addition, an increased molar vertical position was found in the group without posterior discrepancy. Some variables closely related with the individual's intrinsic craniofacial development that could influence the evaluated vertical measurements were not considered. Overall maxillary posterior discrepancy does not appear to have a clear impact on upper molar vertical position or facial vertical dimensions. Only the SOB Class III group without posterior discrepancy had a significant increased upper molar vertical position. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Extracellular Matrix-mediated Tissue Remodeling Following Axial Movement of Teeth

PubMed Central

Luan, Xianghong; Ito, Yoshihiro; Holliday, Sean; Walker, Cameron; Daniel, Jon; Galang, Therese M.; Fukui, Tadayoshi; Yamane, Akira; Begole, Ellen; Evans, Carla; Diekwisch, Thomas G.H.

2007-01-01

SUMMARY Tooth eruption is a multifactorial process involving movement of existing tissues and formation of new tissues coordinated by a complex set of genetic events. We have used the model of the unopposed rodent molar to study morphological and genetic mechanisms involved in axial movement of teeth. Following extraction of opposing upper molars, lower molars supererupted by 0.13 mm. Labeled tissue sections revealed significant amounts of new bone and cementum apposition at the root apex of the unopposed side following supereruption for 12 days. Newly apposited cementum and alveolar bone layers were approximately 3-fold thicker in the experimental vs the control group, whereas periodontal ligament width was maintained. Tartrate-resistant acid phosphatase staining indicated bone resorption at the mesial alveolar walls of unopposed molars and provided in tandem with new bone formation at the distal alveolar walls an explanation for the distal drift of molars in this model. Microarray analysis and semiquantitative RT-PCR demonstrated a significant increase in collagen I, integrin β5, and SPARC gene expression as revealed by comparison between the unopposed molar group and the control group. Immunohistochemical verification revealed increased levels of integrin β5 and SPARC labeling in the periodontal ligament of the unopposed molar. Together our findings suggest that posteruptive axial movement of teeth was accomplished by significant formation of new root cementum and alveolar bone at the root apex in tandem with upregulation of collagen I, integrin β5, and SPARC gene expression. PMID:17015623

Preparation of Si3N4 Form Diatomite via a Carbothermal Reduction-Nitridation Process

NASA Astrophysics Data System (ADS)

Ma, Bin; Huang, Zhaohui; Mei, Lefu; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Hu, Xiaozhi

2016-05-01

Si3N4 was produced using diatomite and sucrose as silicon and carbon sources, respectively. The effect of the C/SiO2 molar ratio, heating temperature and soaking time on the morphology and phase compositions of the final products was investigated by scanning electron microscopy, x-ray diffraction analysis and energy dispersive spectroscopy. The phase equilibrium relationships of the system at different heating temperatures were also investigated based on the thermodynamic analysis. The results indicate that the phase compositions depended on the C/SiO2 molar ratio, heating temperature and soaking time. Fabrication of Si3N4 from the precursor via carbothermal reduction nitridation was achieved at 1550°C for 1-8 h using a C/SiO2 molar ratio of 3.0. The as-prepared Si3N4 contained a low amount of Fe3Si (<1 wt.%).

Effect of flap design on periodontal healing after impacted third molar extraction: a systematic review and meta-analysis.

PubMed

Chen, Y-W; Lee, C-T; Hum, L; Chuang, S-K

2017-03-01

The extraction of an impacted third molar violates the surrounding soft and bony tissues. The surgeon's access to the tooth, for which there are various surgical approaches, has an important impact on the periodontium of the adjacent second molar. The aim of this review was to analyze the relationships between the different flap techniques and postoperative periodontal outcomes for the mandibular second molars (LM2) adjacent to the impacted mandibular third molars (LM3). An electronic search of MEDLINE and other databases was conducted to identify randomized controlled trials fulfilling the eligibility criteria. To assess the impact of flap design on the periodontal condition, the weighted mean difference of the probing depth reduction (WDPDR) and the weighted mean difference of the clinical attachment level gain (WDCAG) at the distal surface of LM2 were used as the primary outcomes. The results showed that, overall, the different flap techniques had no significant impact on the probing depth reduction (WDPDR -0.14mm, 95% confidence interval -0.44 to 0.17), or on the clinical attachment level gain (WDCAG 0.05mm, 95% confidence interval -0.84 to 0.94). However, a subgroup analysis revealed that the Szmyd and paramarginal flap designs may be the most effective in reducing the probing depth in impacted LM3 extraction, and the envelope flap may be the least effective. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Does 3-dimensional imaging of the third molar reduce the risk of experiencing inferior alveolar nerve injury owing to extraction?: A meta-analysis.

PubMed

Clé-Ovejero, Adrià; Sánchez-Torres, Alba; Camps-Font, Octavi; Gay-Escoda, Cosme; Figueiredo, Rui; Valmaseda-Castellón, Eduard

2017-08-01

Clinicians generally use panoramic radiographic (PR) images to assess the proximity of the mandibular third molar to the inferior alveolar nerve (IAN). However, in cases in which a patient needs to undergo a third-molar extraction, many clinicians also assess computed tomographic (CT) images to prevent nerve damage. Two of the authors independently searched MEDLINE (through PubMed), Cochrane Library, Scopus, and Ovid. The authors included randomized or nonrandomized longitudinal studies whose investigators had compared the number of IAN injuries after third-molar extraction in patients who had undergone preoperative CT with patients who had undergone only PR. The authors analyzed the full text of 26 of the 745 articles they initially selected. They included 6 studies in the meta-analysis. Four of the studies had a high risk of bias, and the investigators of only 1 study had used blinding with the patients. The authors observed no statistically significant differences between groups related to the total number of nerve injuries (risk ratio, 0.96; 95% confidence interval, 0.50 to 1.85; P = .91). The prognosis of the injuries was similar for both groups. Although having preoperative CT images might be useful for clinicians in terms of diagnosing and extracting mandibular third molars, having these CT images does not reduce patients' risk of experiencing IAN injuries nor does it affect their prognosis. Copyright © 2017 American Dental Association. Published by Elsevier Inc. All rights reserved.

Incidence of lingual nerve paraesthesia following mandibular third molar surgery

PubMed Central

Lata, Jeevan; Tiwari, Arunesh K.

2011-01-01

Context: The surgical removal of impacted mandibular third molar is associated with minor but expected complications like pain, swelling, bruising and trismus. The lingual nerve damage sometimes occurs after the removal of mandibular third molar producing impaired sensation or permanent sensory loss. This complication is usually unexpected and unacceptable for the patients particularly if no prior warning has been given. Aims: The aim of the present clinical prospective study was to determine the clinical incidence of lingual nerve injury following mandibular third molar removal and to analyze possible factors for the lingual nerve injury. Settings and Design: Clinical prospective study in the Department of Oral Surgery, Punjab Government Dental College and Hospital, Amritsar. Materials and Methods: Ninety patients were selected randomly, amongst the patients, who reported to our department from January 2009 to December 2009 for the surgical removal of impacted mandibular third molar. To minimize the risk of lingual nerve injury, the standard terence wards incision was made in all cases and only buccal flap was raised. Statistical Analysis: The small number of paraesthesia precluded statistical analysis. Results: Out of 90 patients, six patients were diagnosed with lingual nerve paraesthesia. The overall incidence rate of lingual nerve injury was 6.6%. Conclusions: It can be concluded that lingual nerve paraesthesia can occur with or without reflection of lingual flap in spite of all the measures taken to protect it. It may be contributed to the fact of anatomical variations of lingual nerve. PMID:22639500

Iron and zinc fortification of corn tortilla made either at the household or at industrial scale.

PubMed

Tovar, Luis Raul; Larios-Saldaña, Alfredo

2005-03-01

Fe and Zn deficiencies among the Mexican population are widespread, and one-third of children and women of childbearing age are anemic. Since diets that are Fe-deficient are most probably also Zn-deficient, a proprietary process was developed to fortify corn tortilla with these trace elements at the first stage of treatment with lime. Phytic acid (PA), Ca, Fe, and Zn content were determined, as well as the molar ratios of phytate/Fe, phytate/Zn, and Ca x phytate to Zn in traditional and fortified tortillas; the Student's t-test was used to detect differences between the treatments (p < 0.001). Contents of Fe and Zn in the fortified tortilla relative to the traditional tortilla were 1.9 and 3.4 times greater than the latter, whereas PA contents showed the opposite result, i.e. traditional tortillas had 1.65 times more PA than the fortified tortilla. Consequently the calculated molar ratios were statistically more favorable for fortified than for traditional tortillas (p < 0.001). The process developed allows making iron- and zinc-fortified tortillas by lime-treating or nixtamalizing corn either at the household, at small-scale tortilla shops, or at industrial scale by using lime fortified with both trace elements. The cost of this fortification is negligible.

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes

NASA Astrophysics Data System (ADS)

Chandra, Sulekh; Gautam, Seema; Rajor, Hament Kumar; Bhatia, Rohit

2015-02-01

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, 1H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand.

A Cohort Study of the Patterns of Third Molar Impaction in Panoramic Radiographs in Saudi Population

PubMed Central

Al-Dajani, Mahmoud; Abouonq, Anas O; Almohammadi, Turki A; Alruwaili, Mohammed K; Alswilem, Rayan O; Alzoubi, Ibrahim A

2017-01-01

Objectives: To evaluate the epidemiological patterns of third molar impaction in a cohort of patients living in the north of Saudi Arabia. Materials and Methods: A retrospective cohort study comprised of analysing 2550 Orthopantomograms (OPGs) belonging to patients who attended Aljouf University College of Dentistry between September 2013 and December 2015. OPGs were examined to determine the frequency of third molar impaction, their levels of eruption and angulations. Mixed effects logistic regression analysis was performed to calculate adjusted odds ratios. Data were weighted by age and sex based on population regional estimates. Results: 1551 patients (60.8%) with a mean age of 33.5 years-old (95%CI: 32.9 to 34) demonstrated 2650 impacted third molars. Third molars were more likely present in patients aged from 20 to 39 years-old (p<0.001); and in mandible more than maxilla (p<0.001). It showed highest vertical impaction and higher impaction rate in mandible than maxilla. Level A impaction was the most common among other levels by 1365 (53.5%). Vertical impaction was the most common pattern (1354 patients; 53.1%). Mesioangular impaction ranked second in mandible, while distoangular impaction ranked second in maxilla. There was no statistically significant difference between males and females concerning impaction frequency, depth levels and angulations. Conclusion: Impacted third molars is still a public health concern among youth and young adults. Vertically impacted mandibular third molars with their occlusal plane at the same level as the occlusal plane of adjacent tooth is the most prevalent pattern of third molar impaction in the northern region of Saudi Arabia. PMID:29387281

Anatomic symmetry of root and root canal morphology of posterior teeth in Indian subpopulation using cone beam computed tomography: A retrospective study

PubMed Central

Felsypremila, Gnanasekaran; Vinothkumar, Thilla Sekar; Kandaswamy, Deivanayagam

2015-01-01

Objective: To investigate the anatomic symmetry of maxillary and mandibular posteriors in Indian subpopulation using cone beam computed tomography (CBCT). Materials and Methods: CBCT images of 246 patients that had at least one noncarious, posterior tooth free of restorations in each quadrant were enrolled for retrospective analysis. A total of 3015 teeth (811 maxillary premolars, 845 mandibular premolars, 738 maxillary molars, and 621 mandibular molars) were analyzed for number of roots and root canals, canal morphology and anatomic symmetry, and concurrent types between the maxilla and mandible. Results: There was no difference in the percentage of symmetry for maxillary first (81.5%) and second (81.5%) premolars. Mandibular second premolars (98.3%) exhibited greater symmetry than mandibular first premolars (96.1%). First molars (77.5% and 82.1%) showed greater symmetry than second molars (70.8% and 78.6%), in both maxillary and mandibular arches, respectively. The most common anatomy observed were: maxillary first premolars – 2 roots with 2 canals, maxillary second premolars – 1 root with 2 canals, mandibular first and second premolars – 1 root with 1 canal, maxillary first and second molars – 3 roots with 4 canals, and mandibular first and second molars – 2 roots with 3 canals. When compared with any other teeth, maximum asymmetry was observed in maxillary second molar (29.2%). Conclusion: The percentage of symmetry observed in the present study varied from 70% to 98% with least percentage of symmetry in maxillary second molars. These data should alert the clinicians while treating homonymous teeth of the same patient. PMID:26929687

Abrasive, Silica Phytoliths and the Evolution of Thick Molar Enamel in Primates, with Implications for the Diet of Paranthropus boisei

PubMed Central

Rabenold, Diana; Pearson, Osbjorn M.

2011-01-01

Background Primates—including fossil species of apes and hominins—show variation in their degree of molar enamel thickness, a trait long thought to reflect a diet of hard or tough foods. The early hominins demonstrated molar enamel thickness of moderate to extreme degrees, which suggested to most researchers that they ate hard foods obtained on or near the ground, such as nuts, seeds, tubers, and roots. We propose an alternative hypothesis—that the amount of phytoliths in foods correlates with the evolution of thick molar enamel in primates, although this effect is constrained by a species' degree of folivory. Methodology/Principal Findings From a combination of dietary data and evidence for the levels of phytoliths in plant families in the literature, we calculated the percentage of plant foods rich in phytoliths in the diets of twelve extant primates with wide variation in their molar enamel thickness. Additional dietary data from the literature provided the percentage of each primate's diet made up of plants and of leaves. A statistical analysis of these variables showed that the amount of abrasive silica phytoliths in the diets of our sample primates correlated positively with the thickness of their molar enamel, constrained by the amount of leaves in their diet (R2 = 0.875; p<.0006). Conclusions/Significance The need to resist abrasion from phytoliths appears to be a key selective force behind the evolution of thick molar enamel in primates. The extreme molar enamel thickness of the teeth of the East African hominin Paranthropus boisei, long thought to suggest a diet comprising predominantly hard objects, instead appears to indicate a diet with plants high in abrasive silica phytoliths. PMID:22163299

FT-Raman spectroscopy, µ-EDXRF spectrometry, and microhardness analysis of the dentin of primary and permanent teeth.

PubMed

Torres, Carolina Paes; Miranda Gomes-Silva, Jaciara; Menezes-Oliveira, Maria Angélica Hueb; Silva Soares, Luís Eduardo; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina

2018-05-01

The chemical compositions (organic and inorganic contents) and mechanical behaviors of the dentin of permanent and deciduous teeth were analyzed and compared using X-ray fluorescence spectrometry (µ-EDXRF) Fourier transform Raman spectroscopy (FT-Raman) and a microhardness test (HD). Healthy fresh human primary and permanent molars (n = 10) were selected, The buccal surfaces facing upwards were stabilized in an acrylic plate, flattened, polished, and submitted to the µ-EDXRF, FT-Raman, and HD analysis. The results of the analysis were subjected to ANOVAs and Mann-Whitney U/Student's t multiple comparisons tests. The data showed similar values for the dentin of the primary and permanent teeth in P content, organic content (amide I peak), inorganic content ( PO43- - 430 and 590), and microhardness, Nevertheless, Ca content and Ca/P weight ratio were higher, and the CO32- peak was lower in the dentin of the permanent teeth compared to primary teeth. It be concluded that despite permanent teeth showed more Ca element, both substrates showed similar behavior of chemical and physical properties. © 2018 Wiley Periodicals, Inc.

Effect of co-existing copper and calcium on the removal of As(V) by reused aluminum oxides.

PubMed

Yang, J K; Park, Y J; Kim, K H; Lee, H Y; Min, K C; Lee, S M

2013-01-01

Among the various heavy metals, arsenic is frequently found in abandoned mine drainage and the environmental fate of arsenic in real aqueous solutions can be highly dependent on the presence of co-existing ions. In this study, removal of arsenate through adsorption on the reused aluminum oxide or through precipitation was investigated in a single and in a binary system as a function of pH and concentration. Different removal behaviors of arsenate were observed in the presence of different cations as well as a variation of the molar ratios of arsenate to cations. Co-operative effects on arsenate removal by precipitation in solution occurred with an increase of copper concentration, while a decrease of arsenate removal resulted in increasing calcium concentration. It was observed that the arsenate removal in the presence of calcium would be highly dependent on the molar ratios of both elements.

Biomechanical factors associated with mandibular cantilevers: analysis with three-dimensional finite element models.

PubMed

Gonda, Tomoya; Yasuda, Daiisa; Ikebe, Kazunori; Maeda, Yoshinobu

2014-01-01

Although the risks of using a cantilever to treat missing teeth have been described, the mechanisms remain unclear. This study aimed to reveal these mechanisms from a biomechanical perspective. The effects of various implant sites, number of implants, and superstructural connections on stress distribution in the marginal bone were analyzed with three-dimensional finite element models based on mandibular computed tomography data. Forces from the masseter, temporalis, and internal pterygoid were applied as vectors. Two three-dimensional finite element models were created with the edentulous mandible showing severe and relatively modest residual ridge resorption. Cantilevers of the premolar and molar were simulated in the superstructures in the models. The following conditions were also included as factors in the models to investigate changes: poor bone quality, shortened dental arch, posterior occlusion, lateral occlusion, double force of the masseter, and short implant. Multiple linear regression analysis with a forced-entry method was performed with stress values as the objective variable and the factors as the explanatory variable. When bone mass was high, stress around the implant caused by differences in implantation sites was reduced. When bone mass was low, the presence of a cantilever was a possible risk factor. The stress around the implant increased significantly if bone quality was poor or if increased force (eg, bruxism) was applied. The addition of a cantilever to the superstructure increased stress around implants. When large muscle forces were applied to a superstructure with cantilevers or if bone quality was poor, stress around the implants increased.

Radiographic evaluation of third-molar development in relation to the chronological age of Turkish children in the southwest Eastern Anatolia region.

PubMed

Karataş, Orhan H; Öztürk, Fırat; Dedeoğlu, Numan; Çolak, Cemil; Altun, Oğuzhan

2013-10-10

To study the chronological age of third-molar mineralisation of Turkish children from the southwest Eastern Anatolia region, the Demirjian staging method was used to determine the stage of the mineralisation of four third molars (18, 28, 38 and 48) and to compare third-molar development by sex and age with the results of previous studies. The study comprised 832 Turkish children from the southwest Eastern Anatolia region aged 6-16 years based on radiological evidence from digital orthopantomograms. The mean age of the 832 patients was 11.03±1.98 years, with 424 males (mean age, 10.97±1.97) and 408 females (mean age, 11.09±2.00). The orthopantomograms were scored by two observers. The Wilcoxon matched-pairs signed-rank test used to assess intra- and inter-observer assessment revealed strong agreement between both observers' measurements. Statistical analysis of the association between sex and age was performed with the Mann-Whitney U-test and the Wilcoxon test. Regression analysis was performed to obtain regression formulae for calculating the dental and the chronological age. The statistical analysis showed a strong correlation between age and third-molar development in males (R(2)=0.61) and females (R(2)=0.63). New equations (age=7.49+0.69, development stage (DS) 38+0.70, DS18) were derived for estimation of the chronological age. The results showed that there was no significant difference in mineralisation between 18 and 28 and 38 and 48 in males or females. For both sexes, the dental age was lower than the chronological age. Males reached the developmental stages earlier than females. In the whole population, the boys' and the girls' dental ages were 0.84 years and 0.16 years earlier, respectively, than their chronological ages. The use of third-molar teeth as a developmental marker is suitable, particularly when comparing the obtained standard deviation with other skeletal-age calculation techniques. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Potassium Benzoate C7H5O2K(s)

NASA Astrophysics Data System (ADS)

Yang, Wei-Wei; di, You-Ying; Yin, Zhen-Fen; Kong, Yu-Xia; Tan, Zhi-Cheng

2009-04-01

Potassium benzoate C7H5O2K (CAS Registry No. 582-25-2) was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction (XRD) techniques were applied to characterize the composition and structure of the compound. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by the least-squares method. Smoothed heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial. In accordance with Hess’s law, a reasonable thermochemical cycle was designed, and 100 mL of 1 mol · dm-3 NaOH solution was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the title compound C7H5O2K (s) was derived to be -(610.94 ± 0.77) kJ · mol-1.

A histological and micro-CT investigation in to the effect of NGF and EGF on the periodontal, alveolar bone, root and pulpal healing of replanted molars in a rat model - a pilot study

PubMed Central

2014-01-01

Background This study aims to investigate, utilising micro-computed tomography (micro-CT) and histology, whether the topical application of nerve growth factor (NGF) and/or epidermal growth factor (EGF) can enhance periodontal, alveolar bone, root and pulpal tissue regeneration while minimising the risk of pulpal necrosis, root resorption and ankylosis of replanted molars in a rat model. Methods Twelve four-week-old male Sprague-Dawley rats were divided into four groups: sham, collagen, EGF and NGF. The maxillary right first molar was elevated and replanted with or without a collagen membrane impregnated with either the growth factors EGF or NGF, or a saline solution. Four weeks after replantation, the animals were sacrificed and the posterior maxilla was assessed using histological and micro-CT analysis. The maxillary left first molar served as the control for the corresponding right first molar. Results Micro-CT analysis revealed a tendency for all replanted molars to have reduced root length, root volume, alveolar bone height and inter-radicular alveolar bone volume. It appears that the use of the collagen membrane had a negative effect while no positive effect was noted with the incorporation of EGF or NGF. Histologically, the incorporation of the collagen membrane was found to negatively affect pulpal, root, periodontal and alveolar bone healing with pulpal inflammation and hard tissue formation, extensive root resorption and alveolar bone fragmentation. The incorporation of EGF and NGF did not improve root, periodontal or alveolar bone healing. However, EGF was found to improve pulp vascularisation while NGF-improved pulpal architecture and cell organisation, although not to the level of the control group. Conclusions Results indicate a possible benefit on pulpal vascularisation and pulpal cell organisation following the incorporation of EGF and NGF, respectively, into the alveolar socket of replanted molars in the rat model. No potential benefit of EGF and NGF was detected in periodontal or root healing, while the use of a collagen membrane carrier was found to have a negative effect on the healing response. PMID:24393534

EDX-Element Analysis of the In Vitro Effect of Fluoride Oral Hygiene Tablets on Artificial Caries Lesion Formation and Remineralization in Human Enamel.

PubMed

Eggerath, J; Kremniczky, T; Gaengler, P; Arnold, W H

2011-01-01

Aim of this in-vitro-study was to assess the remineralization potential of a tooth cleaning tablet with different fluoride content quantitatively using EDX analysis.Twenty three caries free impacted third molars were examined; enamel surfaces were wax coated leaving two 3x4mm windows for exposure to demineralization/remineralization cycles. The teeth were randomly assigned to 4 groups of 5 control and 6 experimental teeth each. Demineralization by standardized HEC-gel, pH 4.7 at 37°C for 72h, was alternated by rinsing in remineralization solution, pH 7.0 at 37°C for 72h, total challenge time 432h. The negative control group N was treated during remineralization cycles with saline; positive control group P was treated with remineralization solution; experimental group D1 was exposed to remineralization solution containing Denttabs(®)-tablets with 1450 ppm F; experimental group D2 was exposed to remineralization solution and Denttabs(®)-tablets with 4350 ppm F. Each tooth was cut into serial sections and analyzed by scanning electron microscopy with EDX element analysis for assessment of the different zones of the lesions in 3 representative sections. Statistical analysis was based on the AVOVA test for repeated measurements and post hoc Bonferroni adjustment. The results showed a significantly higher Ca and P content in the body of the lesion in both fluoride treated groups compared to the controls. It can be concluded that higher concentrations of NaF may be more effective in remineralization of early advanced caries lesions.

EDX-Element Analysis of the In Vitro Effect of Fluoride Oral Hygiene Tablets on Artificial Caries Lesion Formation and Remineralization in Human Enamel

PubMed Central

Eggerath, J; Kremniczky, T; Gaengler, P; Arnold, W.H

2011-01-01

Aim of this in-vitro-study was to assess the remineralization potential of a tooth cleaning tablet with different fluoride content quantitatively using EDX analysis. Twenty three caries free impacted third molars were examined; enamel surfaces were wax coated leaving two 3x4mm windows for exposure to demineralization/remineralization cycles. The teeth were randomly assigned to 4 groups of 5 control and 6 experimental teeth each. Demineralization by standardized HEC-gel, pH 4.7 at 37°C for 72h, was alternated by rinsing in remineralization solution, pH 7.0 at 37°C for 72h, total challenge time 432h. The negative control group N was treated during remineralization cycles with saline; positive control group P was treated with remineralization solution; experimental group D1 was exposed to remineralization solution containing Denttabs®-tablets with 1450 ppm F; experimental group D2 was exposed to remineralization solution and Denttabs®-tablets with 4350 ppm F. Each tooth was cut into serial sections and analyzed by scanning electron microscopy with EDX element analysis for assessment of the different zones of the lesions in 3 representative sections. Statistical analysis was based on the AVOVA test for repeated measurements and post hoc Bonferroni adjustment. The results showed a significantly higher Ca and P content in the body of the lesion in both fluoride treated groups compared to the controls. It can be concluded that higher concentrations of NaF may be more effective in remineralization of early advanced caries lesions. PMID:21687564

Influence of different restorative materials on the stress distribution in dental implants.

PubMed

Datte, Carlos-Eduardo; Tribst, João-Paulo-Mendes; Dal Piva, Amanda-Maria-de Oliveira; Nishioka, Renato-Sussumu; Bottino, Marco-Antonio; Evangelhista, Alexandre-Duarte M; Monteiro, Fabrício M de M; Borges, Alexandre-Luiz-Souto

2018-05-01

To assist clinicians in deciding the most suitable restorative materials to be used in the crowns and abutment in implant rehabilitation. For finite element analysis (FEA), a regular morse taper implant was created using a computer aided design software. The implant was inserted at the bone model with 3 mm of exposed threads. An anatomic prosthesis representing a first maxillary molar was modeled and cemented on the solid abutment. Considering the crown material (zirconia, chromium-cobalt, lithium disilicate and hybrid ceramic) and abutment (Titanium and zirconia), the geometries were multiplied, totaling eight groups. In order to perform the static analysis, the contacts were considered bonded and each material was assigned as isotropic. An axial load (200 N) was applied on the crown and fixation occurred on the base of the bone. Results using Von-Mises criteria and micro strain values were obtained. A sample identical to the CAD model was made for the Strain Gauge (SG) analysis; four SGs were bonded around the implant to obtain micro strain results in bone tissue. FEA results were 3.83% lower than SG. According to the crown material, it is possible to note that the increase of elastic modulus reduces the stress concentration in all system without difference for bone. Crown materials with high elastic modulus are able to decrease the stress values in the abutments while concentrates the stress in its structure. Zirconia abutments tend to concentrate more stress throughout the prosthetic system and may be more susceptible to mechanical problems than titanium. Key words: Finite element analysis, dental implants, ceramic.

Comparative Evaluation of Immediate Post-Operative Sequelae after Surgical Removal of Impacted Mandibular Third Molar with or without Tube Drain - Split-Mouth Study.

PubMed

Kumar, Barun; Bhate, Kalyani; Dolas, R S; Kumar, Sn Santhosh; Waknis, Pushkar

2016-12-01

Third molar surgery is one of the most common surgical procedures performed in general dentistry. Post-operative variables such as pain, swelling and trismus are major concerns after impacted mandibular third molar surgery. Use of passive tube drain is supposed to help reduce these immediate post-operative sequelae. The current study was designed to compare the effect of tube drain on immediate post-operative sequelae following impacted mandibular third molar surgery. To compare the post-operative sequelae after surgical removal of impacted mandibular third molar surgery with or without tube drain. Thirty patients with bilateral impacted mandibular third molars were divided into two groups: Test (with tube drain) and control (without tube drain) group. In the test group, a tube drain was inserted through the releasing incision, and kept in place for three days. The control group was left without a tube drain. The post-operative variables like, pain, swelling, and trismus were calculated after 24 hours, 72 hours, 7 days, and 15 days in both the groups and analyzed statistically using chi-square and t-test analysis. The test group showed lesser swelling as compared to control group, with the swelling variable showing statistically significant difference at post-operative day 3 and 7 (p≤ 0.05) in both groups. There were no statistically significant differences in pain and trismus variables in both the groups. The use of tube drain helps to control swelling following impacted mandibular third molar surgery. However, it does not have much effect on pain or trismus.

A study of root canal morphology of human primary incisors and molars using cone beam computerized tomography: an in vitro study.

PubMed

Gaurav, Vivek; Srivastava, Nikhil; Rana, Vivek; Adlakha, Vivek Kumar

2013-01-01

Variations in morphology of root canals in primary teeth usually leads to complications during and after endodontic therapy. To improve the success in endodontics, a thorough knowledge of the root canal morphology is essential. The aim of this study was to assess the variation in number and morphology of the root canals of primary incisors and molars and to study the applicability of cone beam computerized tomography (CBCT) in assessing the same. A total of 60 primary molars and incisors with full root length were collected and various parameters such as the number of roots, number of canals, diameter of root canal at cementoenamel junction and middle-third, length and angulations of roots of primary molars and incisors were studied using CBCT. The observations were put to descriptive statistics to find out the frequency, mean, standard deviation and range for all four subgroups. Further, unpaired t-test was used to compare these parameters between subgroups and analysis of variance test was implemented to evaluate the parameters within the subgroups. The CBCT showed the presence of bifurcation of root canal at middle third in 13% of mandibular incisors while 20% of mandibular molars had two canals in distal root. The diameter of distobuccal root canal of maxillary molars and mesiolingual canal of mandibular molars was found to be minimum. CBCT is a relatively new and effective technology, which provides an auxiliary imaging modality to supplement conventional radiography for assessing the variation in root canal morphology of primary teeth.

Investigation of Clinical Characteristics and Etiological Factors in Children with Molar Incisor Hypomineralization

PubMed Central

Giuca, Maria Rita; Cappè, Maria; Carli, Elisabetta; Lardani, Lisa

2018-01-01

Aim The purpose of the present study was to evaluate the clinical defects and etiological factors potentially involved in the onset of MIH in a pediatric sample. Methods 120 children, selected from the university dental clinic, were included: 60 children (25 boys and 35 girls; average age: 9.8 ± 1.8 years) with MIH formed the test group and 60 children (27 boys and 33 girls; average age: 10.1 ± 2 years) without MIH constituted the control group. Distribution and severity of MIH defects were evaluated, and a questionnaire was used to investigate the etiological variables; chi-square, univariate, and multivariate statistical tests were performed (significance level set at p < 0.05). Results A total of 186 molars and 98 incisors exhibited MIH defects: 55 molars and 75 incisors showed mild defects, 91 molars and 20 incisors had moderate lesions, and 40 molars and 3 incisors showed severe lesions. Univariate and multivariate statistical analysis showed a significant association (p < 0.05) between MIH and ear, nose, and throat (ENT) disorders and the antibiotics used during pregnancy (0.019). Conclusions Moderate defects were more frequent in the molars, while mild lesions were more frequent in the incisors. Antibiotics used during pregnancy and ENT may be directly involved in the etiology of MIH in children. PMID:29861729

Effects of unilateral molar distalization with a modified pendulum appliance.

PubMed

Schütze, Stefan F; Gedrange, Tomas; Zellmann, Markus R; Harzer, Winfried

2007-05-01

The purpose of this study was to evaluate skeletal and dentoalveolar changes due to unilateral distalization and to determine side effects. Cephalograms and dental casts before and after distal movement of the maxillary molars with pendulum appliances in 15 consecutively treated patients (5 girls and 10 boys, 12.06 +/- 1.32 years), were included in this study. The duration of distalization was 8.46 +/- 2.23 months. Cephalometric analysis showed no remarkable growth between the 2 measurement times. The mean value for distalization of the first molars was 3.83 +/- 1.09 mm, with distal tipping of 6.45 degrees . The maxillary second molars were also moved distally 2.83 +/- 1.32 mm and tipped distally 14.7 degrees . No significant changes in the position of the third molars were measured. The mean reciprocal mesial movement of the premolars was 1.18 +/- 1.31 mm, with distal tipping of 1.94 degrees . The incisors moved 0.84 +/- 0.79 mm mesially, with mesial tipping of 0.02 degrees and extrusion of 1.21 mm. There was also a significant influence on the contralateral anchorage unit. However, unilateral distalization reduced incisor proclination and induced moderate distal movement of the contralateral anchorage unit based on rotation around a virtual axis perpendicular to the Nance button. Effective distal molar movement and less anchorage loss at the front teeth are advantages of unilateral distalization.

Three-dimensional finite element analyses of four designs of a high-strength silicon nitride implant.

PubMed

Lin, S; Shi, S; LeGeros, R Z; LeGeros, J P

2000-01-01

The effects of implant shape and size on the stress distribution around high-strength silicon nitride implants under vertical and oblique forces were determined using a three-dimensional finite element analysis. Finite element models were designed using as a basis the serial sections of the mandible. Using Auto-CAD software, the model simulated the placement of implants in the molar region of the left mandible. Results of the analyses demonstrated that mainly the implant root shape and the directions of bite forces influence the stress distributions in the supporting bone around each implant. Implant size is a lesser factor. The serrated implants presented a larger surface area to the bone than either the cylindrical or tapered implants, which resulted in lower compressive stress around the serrated implants. With increasing implant diameter and length, compressive stress decreased. The mean compressive stress distribution on the serrated implants was more flat (platykurtic) than on either the cylindrical or tapered implants. Results of studies on two load directions (vertical and oblique) showed that, in either case, the compressive stress in the cortical bone around the neck of the implant was higher than in the cancellous bone along the length of the implant. The most extreme principal compressive stress was found with oblique force. This study provides the first information on the relationship between shape of the silicon nitride implant and stress on the supporting bone.

Quasi-planar elemental clusters in pair interactions approximation

NASA Astrophysics Data System (ADS)

Chkhartishvili, Levan

2016-01-01

The pair-interactions approximation, when applied to describe elemental clusters, only takes into account bonding between neighboring atoms. According to this approach, isomers of wrapped forms of 2D clusters - nanotubular and fullerene-like structures - and truly 3D clusters, are generally expected to be more stable than their quasi-planar counterparts. This is because quasi-planar clusters contain more peripheral atoms with dangling bonds and, correspondingly, fewer atoms with saturated bonds. However, the differences in coordination numbers between central and peripheral atoms lead to the polarization of bonds. The related corrections to the molar binding energy can make small, quasi-planar clusters more stable than their 2D wrapped allotropes and 3D isomers. The present work provides a general theoretical frame for studying the relative stability of small elemental clusters within the pair interactions approximation.

Does Topical Ozone Therapy Improve Patient Comfort After Surgical Removal of Impacted Mandibular Third Molar? A Randomized Controlled Trial.

PubMed

Sivalingam, Varun P; Panneerselvam, Elavenil; Raja, Krishnakumar V B; Gopi, Gayathri

2017-01-01

To assess the influence of topical ozone administration on patient comfort after third molar surgery. A single-blinded randomized controlled clinical trial was designed involving patients who required removal of bilateral impacted mandibular third molars. The predictor variable was the postoperative medication used after third molar surgery. Using the split-mouth design, the study group received topical ozone without postoperative systemic antibiotics, whereas the control group did not receive ozone but only systemic antibiotics. The 2 groups were prescribed analgesics for 2 days. The assessing surgeon was blinded to treatment assignment. The primary outcome variables were postoperative mouth opening, pain, and swelling. The secondary outcome variable was the number of analgesic doses required by each group on postoperative days 3 to 5. Data analysis involved descriptive statistics, paired t tests, and 2-way analysis of variance with repeated measures (P < .05). SPSS 20.0 was used for data analysis. The study sample included 33 patients (n = 33 in each group). The study group showed statistically relevant decreases in postoperative pain, swelling, and trismus. Further, the number of analgesics required was smaller than in the control group. No adverse effects of ozone gel were observed in any patient. Ozone gel was found to be an effective topical agent that considerably improves patient comfort postoperatively and can be considered a substitute of postoperative systemic antibiotics. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Diagnostic value of panoramic radiography in predicting inferior alveolar nerve injury after mandibular third molar extraction: a meta-analysis.

PubMed

Liu, W; Yin, W; Zhang, R; Li, J; Zheng, Y

2015-06-01

The aim of this study was to evaluate the predictive value of panoramic radiography on inferior alveolar nerve (IAN) injury after extraction of the mandibular third molar. Relevant studies up to 1 June 2014 that discussed the association of panoramic radiography signs and post-mandibular third molar extraction IAN injury were systematically retrieved from the databases of PubMed, Embase, Springerlink, Web of Science and Cochrane library. The effect size of pooled sensitivity, specificity, positive likelihood ratios (PLR), negative likelihood ratios (NLR) and diagnostic odds ratio (DOR) with their 95% confidence intervals (CI) were statistically analysed with Meta-disc 1.4 software. Nine articles were included in this meta-analysis. The pooled estimates of sensitivity and specificity were 0.56 (95% CI: 0.50-0.61) and 0.86 (95% CI: 0.84-0.87), respectively. The overall PLR was 3.46 (95% CI: 2.02-5.92) and overall NLR was 0.58 (95% CI: 0.45-0.73). The pooled estimate of DOR was 6.49 (95% CI: 2.92-14.44). The area under the summary receiver operating characteristic curve was 0.7143 ± 0.0604. The meta-analysis indicated that interpretation of panoramic radiography based on darkening of the root had a high specificity in predicting IAN injury after mandibular third molar extraction. However, the ability of this panoramic radiography marker to detect true positive IAN injury was not satisfactory. © 2015 Australian Dental Association.

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body

PubMed Central

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

Aim: To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Materials and Methods: Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. Results: The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Conclusion: Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification. PMID:26005300

Crystal Structure and Photocatalytic Activity of Al-Doped TiO2 Nanofibers for Methylene Blue Dye Degradation.

PubMed

Lee, Deuk Yong; Lee, Myung-Hyun; Kim, Bae-Yeon; Cho, Nam-Ihn

2016-05-01

Al-TiO2 nanofibers were prepared using a sol-gel derived electrospinning by varying the Al/Ti molar ratio from 0 to 0.73 to investigate the effect of Al doping on the crystal structure and the photocatalytic activity of Al-TiO2 for methylene blue (MB) degradation. XRD results indicated that as the Al/Ti molar ratio rose, crystal structure of Al-TiO2 was changed from anatase/rutile (undoped), anatase (0.07-0.18), to amorphous phase (0.38-0.73), which was confirmed by XPS and Raman analysis. The degradation kinetic constant increased from 7.3 x 10(-4) min(-1) to 4.5 x 10(-3) min(-1) with the increase of Al/Ti molar ratios from 0 to 0.38, but decreased to 3.4 x 10(-3) min(-1) when the Al/Ti molar ratio reached 0.73. The Al-TiO2 catalyst doped with 0.38 Al/Ti molar ratio demonstrated the best MB degradation. Experimental results indicated that the Al doping in Al-TiO2 was mainly attributed to the crystal structure of TiO2 and the photocatalytic degradation of MB.

Factors associated with complications of removal of third molars: a transversal study.

PubMed

Barbosa-Rebellato, Nelson-Luis; Thomé, Ana-Carolina; Costa-Maciel, Cássia; Oliveira, Jaina; Scariot, Rafaela

2011-05-01

The purpose of this study is to estimate the overall frequency of complications associated with third molars (M3) removal and to identify the risk factors associated with these complications. To the transversal analysis, a researcher confidentially reviewed the records of all M3 surgery patients. The predictor variables were demographic (i.e. age and gender), localization and position of third molar, bone removal and tooth sectioning. 210 patients had one or more third molars teeth removed, a total of 605 teeth. The sample's mean age was 21.6±9.2 years, with 1,4 woman to 1 man. Postoperative complications were recorded in 54 extractions of third molars. The most common complications were infection (42.6%), followed by radicular fractures (11.1%) and gingival alterations (11.1%). Complications were significantly affected by 3 factors: age over 25 years old (p=0.002--OR 2.21), location (p=0.006--OR 2.36), bone removal (p=0.002--OR 3.03) and tooth sectioning (p=0.00002--OR 3.59). The results of these analyses suggest that age, location of the tooth, bone removal and tooth sectioning appear to be associated with a higher complication rate for M3 extractions.

Radiologic assessment of third molar tooth and spheno-occipital synchondrosis for age estimation: a multiple regression analysis study.

PubMed

Demirturk Kocasarac, Husniye; Sinanoglu, Alper; Noujeim, Marcel; Helvacioglu Yigit, Dilek; Baydemir, Canan

2016-05-01

For forensic age estimation, radiographic assessment of third molar mineralization is important between 14 and 21 years which coincides with the legal age in most countries. The spheno-occipital synchondrosis (SOS) is an important growth site during development, and its use for age estimation is beneficial when combined with other markers. In this study, we aimed to develop a regression model to estimate and narrow the age range based on the radiologic assessment of third molar and SOS in a Turkish subpopulation. Panoramic radiographs and cone beam CT scans of 349 subjects (182 males, 167 females) with age between 8 and 25 were evaluated. Four-stage system was used to evaluate the fusion degree of SOS, and Demirjian's eight stages of development for calcification for third molars. The Pearson correlation indicated a strong positive relationship between age and third molar calcification for both sexes (r = 0.850 for females, r = 0.839 for males, P < 0.001) and also between age and SOS fusion for females (r = 0.814), but a moderate relationship was found for males (r = 0.599), P < 0.001). Based on the results obtained, an age determination formula using these scores was established.

Association between third molar agenesis and craniofacial structure development.

PubMed

Ramiro-Verdugo, Jara; De Vicente-Corominas, Elena; Montiel-Company, José María; Gandía-Franco, José Luís; Bellot-Arcís, Carlos

2015-11-01

The aim of this investigation was to study the relationship between third molar agenesis-including the number of ageneses-and craniofacial structure growth. We reviewed 305 clinical histories of patients treated at the Orthodontics Unit of the Faculty of Medicine and Dentistry at the University of Valencia in Spain. This included radiographic records of optimal quality. Of these, 40 patients who had agenesis of at least 1 third molar were included in the study group. A control group was formed with another 40 patients with all 4 third molars present. For both groups, a further criterion for inclusion was cone-beam computed tomography records. The cephalometric analysis was performed with NemoCeph 3D software (version 11.3.1.38; Nemotec, Madrid, Spain). The only significant differences between the 2 groups were in the total gonial angle and the upper gonial angle (P ≤0.05), both of which were smaller in the study group. Third molar agenesis is associated with a reduction in Jarabak's gonial angle and upper gonial angle, characteristic of patients with a more horizontal or brachyfacial skeletal pattern. No significant differences were found in other measurements. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Quality of life after upper third molar removal: A prospective longitudinal study

PubMed Central

Avellaneda-Gimeno, Vanesa; Valmaseda-Castellón, Eduard

2017-01-01

Background Third molar extraction is a very common procedure in Dentistry. The aim of this study was to evaluate the quality of life (QoL) and satisfaction of patients undergoing extraction of an upper third molar under local anesthesia. A second objective was to describe the evolution of self-reported pain measured in a visual analogue scale (VAS) in the 7 days after surgery and its relationship with pre- and intraoperative factors. Material and Methods A prospective longitudinal cohort study was made. Fifty-five patients received a questionnaire assessing social and working isolation, eating and speaking ability, diet modifications, sleep impairment, physical appearance, discomfort at suture removal and overall satisfaction. Pain was registered daily on a VAS scale. A descriptive and bivariate analysis of the data was performed. Results Forty-seven patients were included. Pain decreased lineally across the 7 days, and relief was significant between days 2 and 3. Intraoperative complications were significantly associated with pain. The complication that showed the highest pain score was the tuberosity fracture. Conclusions Upper third molar removal significantly affects the patient’s quality of life, particularly during the first 2 days after extraction. Key words:Quality of life, upper third molar, extraction, complications. PMID:29053650

Distal displacement of the maxilla and the upper first molar.

PubMed

Baumrind, S; Molthen, R; West, E E; Miller, D M

1979-06-01

Data from a sample of 198 Class II cases treated with various appliances which deliver distally directed forces to the maxilla were examined to determine the frequency of absolute distal displacement of the upper first molar and of the maxilla. Analysis revealed that such distal displacement is possible and that it is, in fact, a frequent finding following treatment. Long-range stability of distal displacement was not assessed.

Microbiological assessment of root canals following use of rotary and manual instruments in primary molars.

PubMed

Subramaniam, Priya; Tabrez, T A; Babu, K L Girish

2013-01-01

To assess the microflora of root canals in primary molars following use of rotary NiTi files and conventional hand NiTi and stainless steel files. This randomized clinical trial consisted of a total of 60 first and second primary molars requiring root canal treatment, who were selected from children aged 5-9 years. Based on type of root canal instrumentation, the teeth were randomly assigned to three groups of twenty teeth each; Group A: Rotary NiTi files, Group B: Hand NiTi files and Group C: Hand stainless steel files. Following administration of local anesthesia, isolation with rubber dam was carried out. For the purpose of instrumentation and sampling, the palatal canal of maxillary molars and the distal canal of mandibular molars were selected. Prior to sampling, the orifices of other canals in these teeth were sealed, so as to prevent any contamination. Instrumentation was carried out in each group using respective instruments along with intermittent saline irrigation. Root canal samples were obtained both before and after instrumentation, using sterile absorbent paper points and transferred to a sterile vial with transport fluid. Serial dilutions were prepared and cultured on suitable agar media. Both aerobic and anaerobic microbial counts were made. Data obtained was subjected to statistical analysis using Wilcoxon signed rank test and one-way Analysis of variance. In all three groups, there was a significant reduction in both aerobic and anaerobic mean microbial count following root canal instrumentation. (p < 0.001). Rotary NiTi files were as efficient as conventional hand instruments in significantly reducing the root canal microflora.

Triple paternal contribution to a normal/complete molar chimeric singleton placenta.

PubMed

Ariel, I; Goldman-Wohl, D; Yagel, S; Gazit, E; Loewenthal, R

2017-05-01

A comprehensive study of unusual cases of placental pathology may provide insight into mechanisms of normal human fertilization and early embryonic development by examining the exception to the rule. A gravida three para two 39-year-old woman was monitored by ultrasound from 16 weeks of gestation for cystic placenta. A female newborn was born at 36 weeks gestation. Pathologic examination of the partially cystic placenta revealed a singleton placenta comprised of 2/3 normal placenta and 1/3 complete hydatidiform mole, largely degenerated. Immunostaining for p57 was negative in stromal cells of the molar villi. Chromogenic in-situ hybridization revealed diploidy in both normal and molar parts. A total of 16 microsatellites were studied by short tandem repeat analysis, 11 of which were informative. The analysis revealed bipaternal molar tissue of dispermic origin. The paternal monospermic contribution to the normal part was different from that in the molar part, thus resulting in tripaternal contribution to the conceptus. A chimera is a single organism composed of two or more different populations of genetically distinct cells that originated from different zygotes (tetragametic) whereas mosaic is a mixture of two cell lines in one organism originating from one zygote. The possible mechanisms leading to the formation of chimeric/mosaic placenta in our case (one of the components being complete hydatidiform mole), including twinning, fusion at an early embryonic stage and diploidization of triploids, are discussed. © The Author 2017. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-05-01

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

Studies on DNA binding behaviour of biologically active transition metal complexes of new tetradentate N2O2 donor Schiff bases: inhibitory activity against bacteria.

PubMed

Sobha, S; Mahalakshmi, R; Raman, N

2012-06-15

A series of Cu(II), Ni(II) and Zn(II) complexes of the type ML have been synthesized with Schiff bases derived from o-acetoacetotoluidide, 2-hydroxybenzaldehyde and o-phenylenediamine/1,4-diaminobutane. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytic in nature. All the six metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The analytical data helped to elucidate the structure of the metal complexes. The Schiff bases are found to act as tetradentate ligands using N(2)O(2) donor set of atoms leading to a square-planar geometry for the complexes around all the metal ions. The binding properties of metal complexes with DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. Detailed analysis reveals that the metal complexes intercalate into the DNA base stack as intercalators. All the metal complexes cleave the pUC19 DNA in presence of H(2)O(2.) The Schiff bases and their complexes have been screened for their antibacterial activity against five bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae) by disk diffusion method. All the metal complexes have potent biocidal activity than the free ligands. Copyright © 2012 Elsevier B.V. All rights reserved.

Biosorption of Pb (II) from aqueous solution by extracellular polymeric substances extracted from Klebsiella sp. J1: Adsorption behavior and mechanism assessment

NASA Astrophysics Data System (ADS)

Wei, Wei; Wang, Qilin; Li, Ang; Yang, Jixian; Ma, Fang; Pi, Shanshan; Wu, Dan

2016-08-01

The adsorption performance and mechanism of extracellular polymeric substances (EPS) extracted from Klebsiella sp. J1 for soluble Pb (II) were investigated. The maximum biosorption capacity of EPS for Pb (II) was found to be 99.5 mg g-1 at pH 6.0 and EPS concentration of 0.2 g/L. The data for adsorption process satisfactorily fitted to both Langmuir isotherm and pseudo-second order kinetic model. The mean free energy E and activation energy Ea were determined at 8.22- 8.98 kJ mol-1 and 42.46 kJ mol-1, respectively. The liquid-film diffusion step might be the rate-limiting step. The thermodynamic parameters (ΔGo, ΔHo and ΔSo) revealed that the adsorption process was spontaneous and exothermic under natural conditions. The interactions between EPS system and Pb (II) ions were investigated by qualitative analysis methods (i.e Zeta potential, FT-IR and EDAX). Based on the strong experimental evidence from the mass balance of the related elements participating in the sorption process, an ion exchange process was identified quantitatively as the major mechanism responsible for Pb (II) adsorption by EPS. Molar equivalents of both K+ and Mg2+ could be exchanged with Pb2+ molar equivalents in the process and the contribution rate of ion exchange to adsorption accounted for 85.72% (Δmequiv = -0.000541).

Biosorption of Pb (II) from aqueous solution by extracellular polymeric substances extracted from Klebsiella sp. J1: Adsorption behavior and mechanism assessment

PubMed Central

Wei, Wei; Wang, Qilin; Li, Ang; Yang, Jixian; Ma, Fang; Pi, Shanshan; Wu, Dan

2016-01-01

The adsorption performance and mechanism of extracellular polymeric substances (EPS) extracted from Klebsiella sp. J1 for soluble Pb (II) were investigated. The maximum biosorption capacity of EPS for Pb (II) was found to be 99.5 mg g−1 at pH 6.0 and EPS concentration of 0.2 g/L. The data for adsorption process satisfactorily fitted to both Langmuir isotherm and pseudo-second order kinetic model. The mean free energy E and activation energy Ea were determined at 8.22– 8.98 kJ mol−1 and 42.46 kJ mol−1, respectively. The liquid-film diffusion step might be the rate-limiting step. The thermodynamic parameters (ΔGo, ΔHo and ΔSo) revealed that the adsorption process was spontaneous and exothermic under natural conditions. The interactions between EPS system and Pb (II) ions were investigated by qualitative analysis methods (i.e Zeta potential, FT-IR and EDAX). Based on the strong experimental evidence from the mass balance of the related elements participating in the sorption process, an ion exchange process was identified quantitatively as the major mechanism responsible for Pb (II) adsorption by EPS. Molar equivalents of both K+ and Mg2+ could be exchanged with Pb2+ molar equivalents in the process and the contribution rate of ion exchange to adsorption accounted for 85.72% (Δmequiv = −0.000541). PMID:27514493

End-Functionalized Palladium SCS Pincer Polymers via Controlled Radical Polymerizations.

PubMed

Lye, Diane S; Cohen, Aaron E; Wong, Madeleine Z; Weck, Marcus

2017-07-01

A direct and facile route toward semitelechelic polymers, end-functionalized with palladated sulfur-carbon-sulfur pincer (Pd II -pincer) complexes is reported that avoids any post-polymerization step. Key to our methodology is the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization with functionalized chain-transfer agents. This strategy yields Pd end-group-functionalized materials with monomodal molar mass dispersities (Đ) of 1.18-1.44. The RAFT polymerization is investigated using a Pd II -pincer chain-transfer agent for three classes of monomers: styrene, tert-butyl acrylate, and N-isopropylacrylamide. The ensuing Pd II -pincer end-functionalized polymers are analyzed using 1 H NMR spectroscopy, gel-permeation chromatography, and elemental analysis. The RAFT polymerization methodology provides a direct pathway for the fabrication of Pd II -pincer functionalized polymers with complete end-group functionalization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, characterization, antimicrobial, DNA-cleavage and antioxidant activities of 3-((5-chloro-2-phenyl-1H-indol-3-ylimino)methyl)quinoline-2(1H)-thione and its metal complexes

NASA Astrophysics Data System (ADS)

Vivekanand, B.; Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

2015-01-01

Schiff base 3-((5-chloro-2-phenyl-1H-indol-3-ylimino)methyl)quinoline-2(1H)-thione and its Cu(II), Co(II), Ni(II), Zn(II) and Fe(III), complexes have been synthesized and characterized by elemental analysis, UV-Visible, IR, 1H NMR, 13C NMR and mass spectra, molar conductance, magnetic susceptibility, ESR and TGA data. The ligand and its metal complexes have been screened for their antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, antifungal activity against Aspergillus niger and Aspergillus flavus in minimum inhibition concentration (MIC) by cup plate method respectively, antioxidant activity using 1,1-diphenyl-2-picryl hydrazyl (DPPH), which was compared with that of standard drugs vitamin-C and vitamin-E and DNA cleavage activity using calf-thymus DNA.

Automated measurement and monitoring of bioprocesses: key elements of the M(3)C strategy.

PubMed

Sonnleitner, Bernhard

2013-01-01

The state-of-routine monitoring items established in the bioprocess industry as well as some important state-of-the-art methods are briefly described and the potential pitfalls discussed. Among those are physical and chemical variables such as temperature, pressure, weight, volume, mass and volumetric flow rates, pH, redox potential, gas partial pressures in the liquid and molar fractions in the gas phase, infrared spectral analysis of the liquid phase, and calorimetry over an entire reactor. Classical as well as new optical versions are addressed. Biomass and bio-activity monitoring (as opposed to "measurement") via turbidity, permittivity, in situ microscopy, and fluorescence are critically analyzed. Some new(er) instrumental analytical tools, interfaced to bioprocesses, are explained. Among those are chromatographic methods, mass spectrometry, flow and sequential injection analyses, field flow fractionation, capillary electrophoresis, and flow cytometry. This chapter surveys the principles of monitoring rather than compiling instruments.

Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base

NASA Astrophysics Data System (ADS)

Shakir, Mohammad; Khanam, Sadiqa; Firdaus, Farha; Latif, Abdul; Aatif, Mohammad; Al-Resayes, Saud I.

The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV-vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

Spectroscopic studies on Solvatochromism of mixed-chelate copper(II) complexes using MLR technique

NASA Astrophysics Data System (ADS)

Golchoubian, Hamid; Moayyedi, Golasa; Fazilati, Hakimeh

2012-01-01

Mixed-chelate copper(II) complexes with a general formula [Cu(acac)(diamine)]X where acac = acetylacetonate ion, diamine = N,N-dimethyl,N'-benzyl-1,2-diaminoethane and X = BPh 4-, PF 6-, ClO 4- and BF 4- have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV-vis and IR spectroscopies. The complexes are solvatochromic and their solvatochromism were investigated by visible spectroscopy. All complexes demonstrated the positive solvatochromism and among the complexes [Cu(acac)(diamine)]BPh 4·H 2O showed the highest Δ νmax value. To explore the mechanism of interaction between solvent molecules and the complexes, different solvent parameters such as DN, AN, α and β using multiple linear regression (MLR) method were employed. The statistical results suggested that the DN parameter of the solvent plays a dominate contribution to the shift of the d-d absorption band of the complexes.

DNA binding, anti-inflammatory and analgesic evaluation of metal complexes of N/S/O donor ligands; Synthesis, spectral characterization

NASA Astrophysics Data System (ADS)

Kumar Naik, K. H.; Ashok, B.; Naik, Nagaraja; Mulla, Jameel Ahmed S.; Prakasha, Avinash

2015-04-01

Transition metal complexes containing tri-dentate NSN donor ligands i.e., 5-((1(aminomethyl)cyclohexyl)methyl)-1,3,4-thiadiazol-2-amine (AMTA) (2) and 5-(2-aminophenyl)-1,3,4-thiadiazol-2-amine (ATA) (4i-ii) have been synthesized. The newly synthesized ligands and their respective complexes were characterized by elemental analysis, molar conductance measurement and various spectral studies [infrared (IR), electronic, and NMR (for ligands only)]. Metal complexes are like [M(AMTA)2], [M(ATA)2] type, where M = Mn(II), Co(II) and Cu(II). The proposed geometries of the complexes are octahedral in nature. The synthesized ligands and their complexes were exhibits effective anti-inflammatory, analgesic and DNA binding activities. All the tested compounds exhibited significant analgesic activity, whereas the compound 4i, 4(ia) and 4(iib) is equipotent with Diclofenac sodium.

Elements in the transcriptional regulatory region flanking herpes simplex virus type 1 oriS stimulate origin function.

PubMed

Wong, S W; Schaffer, P A

1991-05-01

Like other DNA-containing viruses, the three origins of herpes simplex virus type 1 (HSV-1) DNA replication are flanked by sequences containing transcriptional regulatory elements. In a transient plasmid replication assay, deletion of sequences comprising the transcriptional regulatory elements of ICP4 and ICP22/47, which flank oriS, resulted in a greater than 80-fold decrease in origin function compared with a plasmid, pOS-822, which retains these sequences. In an effort to identify specific cis-acting elements responsible for this effect, we conducted systematic deletion analysis of the flanking region with plasmid pOS-822 and tested the resulting mutant plasmids for origin function. Stimulation by cis-acting elements was shown to be both distance and orientation dependent, as changes in either parameter resulted in a decrease in oriS function. Additional evidence for the stimulatory effect of flanking sequences on origin function was demonstrated by replacement of these sequences with the cytomegalovirus immediate-early promoter, resulting in nearly wild-type levels of oriS function. In competition experiments, cotransfection of cells with the test plasmid, pOS-822, and increasing molar concentrations of a competitor plasmid which contained the ICP4 and ICP22/47 transcriptional regulatory regions but lacked core origin sequences resulted in a significant reduction in the replication efficiency of pOS-822, demonstrating that factors which bind specifically to the oriS-flanking sequences are likely involved as auxiliary proteins in oriS function. Together, these studies demonstrate that trans-acting factors and the sites to which they bind play a critical role in the efficiency of HSV-1 DNA replication from oriS in transient-replication assays.

Prevalence of missing and impacted third molars in adults aged 25 years and above

PubMed Central

Jung, Yun-Hoa

2013-01-01

Purpose The purpose of this study was to determine the prevalence of missing and impacted third molars in people aged 25 years and above. Materials and Methods The study sample of 3,799 patients was chosen randomly from patients who visited Pusan National University Dental Hospital and had panoramic radiographs taken. The data collected included presence and impaction state, angulation, and depth of impaction of third molars, and radiographically detected lesions of third molars and adjacent second molars. Results A greater percentage of men than women retained at least one third molar. The incidence of third molars decreased with increasing age. The incidence of partially impacted third molars greatly declined after the age of 30. Vertically impacted maxillary third molars and horizontally impacted mandibular third molars were most frequent in all age groups. Among the maxillary third molars, those impacted below the cervical line of the second molar were most frequent in all age groups, and among the mandibular third molars, deeply impacted third molars were most frequent in those aged over 40. Dental caries was the most common radiographic lesion of the third molars. Mesioangularly impacted third molars showed radiographic lesions in 13 (9.5%) adjacent maxillary second molars and 117 (27.4%) mandibular second molars. Conclusion The number of remaining third molars decreased and the percentage of Class C depth increased with age. Caries was the most frequent lesion in third molars. Partially impacted mesioangular third molars showed a high incidence of caries or periodontal bone loss of the adjacent second molar. Regular oral examination will be essential to keep asymptomatic third molars in good health. PMID:24380060

Synthesis and characterization of nanostructured strontium hexaferrite thin films by the sol-gel method

NASA Astrophysics Data System (ADS)

Masoudpanah, S. M.; Seyyed Ebrahimi, S. A.

2012-07-01

Nanostructured single phase strontium hexaferrite, SrFe12O19, thin films have been synthesized on the (100) silicon substrate using a spin coating sol-gel process. The thin films with various Fe/Sr molar ratios of 8-12 were calcined at different temperatures from 500 to 900 °C. The composition, microstructure and magnetic properties of the SrFe12O19 thin films were characterized using Fourier transform infrared spectroscopy, differential thermal analysis, thermogravimetry, X-ray diffraction, electron microscopy and vibrating sample magnetometer. The results showed that the optimum molar ratio for Fe/Sr was 10 at which the lowest calcination temperature to obtain the single phase strontium hexaferrite thin film was 800 °C. The magnetic measurements revealed that the sample with Fe/Sr molar ratio of 10, exhibited higher saturation magnetization (267.5 emu/cm3) and coercivity (4290 Oe) in comparison with those synthesized under other Fe/Sr molar ratios.

Pre-eruptive intracoronal resorption in a third upper molar: clinical, tomographic and histological analysis.

PubMed

Lenzi, R; Marceliano-Alves, M F; Alves, Frf; Pires, F R; Fidel, S

2017-06-01

Radiolucent or hypodense lesions in the crown of unerupted teeth may be due to pre-eruptive intracoronal resorption. Clinicians must be aware of this risk so that they can diagnose and appropriately treat this condition. The purpose of this study is to present a well-documented clinical case of pre-eruptive intracoronal resorption in an impacted third upper left molar of a 63 year old female patient. This was an unexpected finding, which occurred after cone-beam computed tomography was used to investigate the first upper left molar, which had an acute periradicular abscess. A multidisciplinary team followed up the case to describe clinical, radiographic and histological findings. The available treatment options were discussed, and the tooth extraction was the option chosen. Previous case studies describing such resorption in third upper molars have not been reported. This case shows that all permanent teeth in a pre-eruptive stage must be analysed radiographically to detect early pre-eruptive intracoronal resorption. © 2016 Australian Dental Association.

Effect of Cu Salt Molarity on the Nanostructure of CuO Prolate Spheroid

NASA Astrophysics Data System (ADS)

Sabeeh, Sabah H.; Hussein, Hashim Abed; Judran, Hadia Kadhim

Copper sulfate pentahydrate was used as a source of Cu ion with five different molarities (0.02, 0.05, 0.1, 0.15, 2 and 0.25M). XRD, FE-SEM and TEM techniques all showed that CuO samples have polycrystalline monoclinic structure. CuO prolate spheroid is assembled from nanoparticles as building units. It was demonstrated that the purity, morphology, size range of prolate spheroid and density of nano building units are significantly influenced by Cu precursor’s molarity. The pure phase of CuO prolate spheroid was produced via molarity of 0.2M with crystallite size of 15.1565nm while the particle size of building units ranges from 16nm to 21nm. The stability of CuO nanosuspension or nanofluid was evaluated by zeta potential analysis. The obtained properties of specific structure with large surface area of CuO prolate spheroid make it a promising candidate for wide range of potential applications as in nanofluids for cooling purposes.

Cigarette smoke affects bonding to dentin.

PubMed

Almeida e Silva, Junio S; de Araujo, Edson Medeiro; Araujo, Elito

2010-01-01

This in vitro study evaluated the microtensile bond strength (muTBS) of composite resin bonded to dentin that had been contaminated by cigarette smoke. Ten extracted unerupted human third molars were used: Six molars were prepared for muTBS testing, while the other four molars were assigned to pre- and post-etching scanning electronic microscopy (SEM) analysis. The 20 specimens obtained from the 10 coronal portions were distributed into two experimental groups so that each tooth served as its own control. Group 1 underwent a daily toothbrushing simulation and exposure to a smoking simulation chamber, while Group 2 received only a daily simulated toothbrushing. Student's t-test demonstrated that Group 1 samples demonstrated significantly lower bond strength (49.58 MPa) than Group 2 samples (58.48 MPa). Pre and postetching SEM analysis revealed the presence of contaminants on the dentinal surfaces of the Group 1 specimens. It was concluded that contamination by cigarette smoke decreases the bond strength between dentin and composite resin.

Relationship Between Third Mandibular Molar Angulation and Distal Cervical Caries in the Second Molar.

PubMed

Claudia, Andreescu; Barbu, Horia Mihail; Adi, Lorean; Gultekin, Alper; Reiser, Vadim; Gultekin, Pinar; Mijiritsky, Eitan

2018-03-16

Third lower molar partially erupted is commonly encountered in dental practice. This situation challenges clinicians with the dilemma whether to remove or to monitor it, because this molar can cause pathology of the adjacent second molar. The aim of this retrospective study is to evaluate the relationship between third mandibular molar and distal cervical caries in second molar. This retrospective study analyzed 55 digital orthopantograms of adult patients and a total number of 95 mandibular third molars were assessed for eruption status, angulation, radiographic evidence of caries or restoration in the mandibular third molar, and radiographic evidence of caries or restoration in the distal surface of the mandibular second molar. The distal cervical caries in second molar is associated with fully erupted and partially erupted wisdom molar in horizontal, mesioangular and vertical position and less with presence of caries in third molar. There are caries lesions in distal second molars in mesioangular position when adjacent third molar is caries free.

Saving the 2(nd) Molar from the 3(rd) Is it Really the Guilt of the Tilt?

PubMed

Yadav, Pankaj; Pruthi, Preeti Jain; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

2016-05-01

Clinicians often relate the distal caries in second molars to angulated third molars, which if left undetected can lead to gross decay that may further require removal of the tooth. Due to this fact, many third molars are advised for prophylactic removal to prevent decay in the second molar. But this approach would only be justified when the incidence of decay/loss of second molar due to third molar are reasonably high. We sought to determine incidence of caries experience and also sequel extraction in second molars associated with the third molars. The study was conducted to answer the basic question that whether the incidence of caries and subsequent extraction of second molar due to angulated third molars is high enough to justify the prophylactic removal of third molar or not. This study was conducted on radiographic records of 1187 patients. The effect of tilted third molar on the second molar was measured in relation with three parameters namely level & position of third molar with respect to second molar and the distribution among arches. The results indicated that out of total number of teeth examined only 5.4% of maxillary and 9.6% of mandibular second molars were affected by tilted third molars. Further, only 2.2% of mandibular and 2.9% of maxillary second molars were indicated for extraction. The data was statistically insignificant. It was concluded that distal caries in second molars is not very common. It may be present in some cases of third molar impactions and prophylactic removal of these impacted teeth may not be considered appropriate.

An automated technique to stage lower third molar development on panoramic radiographs for age estimation: a pilot study.

PubMed

De Tobel, J; Radesh, P; Vandermeulen, D; Thevissen, P W

2017-12-01

Automated methods to evaluate growth of hand and wrist bones on radiographs and magnetic resonance imaging have been developed. They can be applied to estimate age in children and subadults. Automated methods require the software to (1) recognise the region of interest in the image(s), (2) evaluate the degree of development and (3) correlate this to the age of the subject based on a reference population. For age estimation based on third molars an automated method for step (1) has been presented for 3D magnetic resonance imaging and is currently being optimised (Unterpirker et al. 2015). To develop an automated method for step (2) based on lower third molars on panoramic radiographs. A modified Demirjian staging technique including ten developmental stages was developed. Twenty panoramic radiographs per stage per gender were retrospectively selected for FDI element 38. Two observers decided in consensus about the stages. When necessary, a third observer acted as a referee to establish the reference stage for the considered third molar. This set of radiographs was used as training data for machine learning algorithms for automated staging. First, image contrast settings were optimised to evaluate the third molar of interest and a rectangular bounding box was placed around it in a standardised way using Adobe Photoshop CC 2017 software. This bounding box indicated the region of interest for the next step. Second, several machine learning algorithms available in MATLAB R2017a software were applied for automated stage recognition. Third, the classification performance was evaluated in a 5-fold cross-validation scenario, using different validation metrics (accuracy, Rank-N recognition rate, mean absolute difference, linear kappa coefficient). Transfer Learning as a type of Deep Learning Convolutional Neural Network approach outperformed all other tested approaches. Mean accuracy equalled 0.51, mean absolute difference was 0.6 stages and mean linearly weighted kappa was 0.82. The overall performance of the presented automated pilot technique to stage lower third molar development on panoramic radiographs was similar to staging by human observers. It will be further optimised in future research, since it represents a necessary step to achieve a fully automated dental age estimation method, which to date is not available.

Relationship between fracture of mandibular condyle and absence of unerupted mandibular third molar-a retrospective study.

PubMed

Rajan, Ritesh; Verma, Dinesh Kumar; Borle, R M; Yadav, Abhilasha

2016-06-01

The purpose of the present study was to find, if there exists, a co-relation between presence of unerupted mandibular third molar and fracture of mandibular condyle. A retrospective, multicenter study was done collecting the data of all mandibular condyle fractures treated from November 2006 till August 2015. Data was collected from the patient's records and radiographs for the following information: age, sex, etiology of fracture, presence and state of lower third molars, and associated fracture. The results were subjected to statistical analysis. Out of 180 patients of condylar fracture, unerupted third molars were present in 35 (19.44 %) cases compared to 145 (80.55 %) cases of condylar fracture where the unerupted third molars were not present. The difference was statistically significant (p < 0.05). In the unerupted third molar present group, isolated bilateral condylar fracture was seen in 4 (11.4 %) cases, bilateral condylar fracture associated with other mandibular fractures in 9 (25.7 %) cases, isolated unilateral condylar fracture in 0 (0.0 %) cases, and unilateral condylar fracture associated with other mandibular fractures in 17 (48.5 %) cases and condylar fracture associated with mid face fractures in 5 (14.2 %) cases. In the unerupted third molar absent group, isolated bilateral condylar fracture was seen in 5 (3.4 %) cases, bilateral condylar fracture associated with other mandibular fractures in 30 (20.6 %) cases, isolated unilateral condylar fracture in 24 (16.5 %) cases, unilateral condylar fracture associated with other mandibular fractures in 73 (50.34 %) cases, and condylar fracture associated with mid face fractures in 13(8.96 %) cases. The difference between the groups was statistically significant (p = 0.032). This study suggests that the fractures of mandibular condylar region have a significantly higher incidence in patients without an unerupted mandibular third molar.

Aggregation Number in Water/n-Hexanol Molecular Clusters Formed in Cyclohexane at Different Water/n-Hexanol/Cyclohexane Compositions Calculated by Titration 1H NMR.

PubMed

Flores, Mario E; Shibue, Toshimichi; Sugimura, Natsuhiko; Nishide, Hiroyuki; Moreno-Villoslada, Ignacio

2017-11-09

Upon titration of n-hexanol/cyclohexane mixtures of different molar compositions with water, water/n-hexanol clusters are formed in cyclohexane. Here, we develop a new method to estimate the water and n-hexanol aggregation numbers in the clusters that combines integration analysis in one-dimensional 1 H NMR spectra, diffusion coefficients calculated by diffusion-ordered NMR spectroscopy, and further application of the Stokes-Einstein equation to calculate the hydrodynamic volume of the clusters. Aggregation numbers of 5-15 molecules of n-hexanol per cluster in the absence of water were observed in the whole range of n-hexanol/cyclohexane molar fractions studied. After saturation with water, aggregation numbers of 6-13 n-hexanol and 0.5-5 water molecules per cluster were found. O-H and O-O atom distances related to hydrogen bonds between donor/acceptor molecules were theoretically calculated using density functional theory. The results show that at low n-hexanol molar fractions, where a robust hydrogen-bond network is held between n-hexanol molecules, addition of water makes the intermolecular O-O atom distance shorter, reinforcing molecular association in the clusters, whereas at high n-hexanol molar fractions, where dipole-dipole interactions dominate, addition of water makes the intermolecular O-O atom distance longer, weakening the cluster structure. This correlates with experimental NMR results, which show an increase in the size and aggregation number in the clusters upon addition of water at low n-hexanol molar fractions, and a decrease of these magnitudes at high n-hexanol molar fractions. In addition, water produces an increase in the proton exchange rate between donor/acceptor molecules at all n-hexanol molar fractions.

Radiographic morphology of intrabony defects in the first molars of patients with localized aggressive periodontitis: Comparison with health and chronic periodontitis.

PubMed

Nibali, L; Tomlins, P; Akcalı, A

2018-04-16

The aim of this study was to describe the radiographic features of the first molars of patients with localized aggressive periodontitis (LAgP) and of their associated intrabony defects and to compare them with a control sample of chronic periodontitis cases and healthy subjects. Data from a total of 93 patients were included in this analysis. First, dental panoramic tomograms of 34 patients with LAgP (131 first molars) and 30 periodontally healthy patients (110 first molars) were compared. Then, periapical radiographs of the first molars of the same patients with LAgP and of 29 patients with chronic periodontitis affected by intrabony defects were analysed. Shorter root trunks were associated with the presence of intrabony defects in patients with LAgP (P = .002 at multilevel logistic regression), also when LAgP molars were compared with healthy subjects (P = .036). Although no difference in defect depth and angle was noted between LAgP and chronic periodontitis intrabony defects, LAgP intrabony defects appeared to be more frequently symmetrical and arch-shaped than in chronic periodontitis (P = .008), with positive predictive value and negative predictive value of for 'wide arch' defect of 87.3% (95% CI = 77.2%-93.3%) and 32.3% (95% CI = 27.7%-37.2%) respectively. First molars of patients with LAgP affected by intrabony defects may have some distinct radiographic anatomical characteristics to those of healthy subjects. The shape of intrabony defects seems to differ between LAgP and chronic periodontitis cases. Further studies need to confirm these features and investigate if they are related to the initiation and progression of periodontitis. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Na/Cl molar ratio changes during a salting cycle and its application to the estimation of sodium retention in salted watersheds.

PubMed

Sun, Hongbing; Huffine, Maria; Husch, Jonathan; Sinpatanasakul, Leeann

2012-08-01

Using soil column experiments and data from natural watersheds, this paper analyzes the changes in Na/Cl molar ratios during a salting cycle of aqueous-soil systems. The soil column experiments involved introducing NaCl salt at various initial concentrations into multiple soil columns. At the start of a salting cycle in the column experiments, sodium was adsorbed more than chloride due to cation exchange processes. As a result, the initial Na/Cl molar ratio in column effluent was lower than 1, but increased thereafter. One-dimensional PHREEQC geochemical transport simulations also were conducted to further quantify these trends under more diverse scenarios. The experimentally determined Na/Cl molar ratio pattern was compared to observations in the annual salting cycle of four natural watersheds where NaCl is the dominant applied road deicing salt. Typically, Na/Cl molar ratios were low from mid-winter to early spring and increased after the bulk of the salt was flushed out of the watersheds during the summer, fall and early winter. The established relationship between the Na/Cl molar ratios and the amount of sodium retention derived from the column experiments and computer simulations present an alternative approach to the traditional budget analysis method for estimating sodium retention when the experimental and natural watershed patterns of Na/Cl molar ratio change are similar. Findings from this study enhance the understanding of sodium retention and help improve the scientific basis for future environmental policies intended to suppress the increase of sodium concentrations in salted watersheds. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparative Evaluation of Immediate Post-Operative Sequelae after Surgical Removal of Impacted Mandibular Third Molar with or without Tube Drain - Split-Mouth Study

PubMed Central

Bhate, Kalyani; Dolas, RS; Kumar, SN Santhosh; Waknis, Pushkar

2016-01-01

Introduction Third molar surgery is one of the most common surgical procedures performed in general dentistry. Post-operative variables such as pain, swelling and trismus are major concerns after impacted mandibular third molar surgery. Use of passive tube drain is supposed to help reduce these immediate post-operative sequelae. The current study was designed to compare the effect of tube drain on immediate post-operative sequelae following impacted mandibular third molar surgery. Aim To compare the post-operative sequelae after surgical removal of impacted mandibular third molar surgery with or without tube drain. Materials and Methods Thirty patients with bilateral impacted mandibular third molars were divided into two groups: Test (with tube drain) and control (without tube drain) group. In the test group, a tube drain was inserted through the releasing incision, and kept in place for three days. The control group was left without a tube drain. The post-operative variables like, pain, swelling, and trismus were calculated after 24 hours, 72 hours, 7 days, and 15 days in both the groups and analyzed statistically using chi-square and t-test analysis. Results The test group showed lesser swelling as compared to control group, with the swelling variable showing statistically significant difference at post-operative day 3 and 7 (p≤ 0.05) in both groups. There were no statistically significant differences in pain and trismus variables in both the groups. Conclusion The use of tube drain helps to control swelling following impacted mandibular third molar surgery. However, it does not have much effect on pain or trismus. PMID:28209003

Clinical study of Mineral Trioxide Aggregate in primary molars. Comparison between Grey and White MTA--a long term follow-up (84 months).

PubMed

Cardoso-Silva, Cristina; Barbería, Elena; Maroto, Myriam; García-Godoy, Franklin

2011-02-01

The aim of the present study was to conduct a clinical and radiographic long-term evaluation of pulpotomy in temporary molars performed with Grey and White Mineral Trioxide Aggregate (MTA) and compare the results of Grey and White MTA pulpotomies in a sample of 233 primary molars with a maximum follow-up period of 84 months. The sample was selected from patients treated at the Department of Pediatric Dentistry, Faculty of Dentistry, Complutense University of Madrid, Spain. This prospective study included first and second primary molars treated with pulpotomy with Grey or White MTA, controlled for a maximum follow-up period of 84 months. Statistical analysis of clinical and radiographic findings was completed using ANOVA (P<0.05). Follow-up evaluations, performed every 6 months, revealed that only 2 molars treated with White MTA presented abscess and pathological mobility. Radiographic examination of the 210 molars revealed unfavourable pulp response in only 6 molars (internal or furcation root resorption), without statistically significant differences between Grey and White MTA. Two radiological findings were noticed: dentine bridge formation and partial or total root canal stenosis. Grey MTA induced a higher percentage of dentine bridges with statistically significant differences (P<0.05), and a higher percentage of pulp canal stenosis, without a statistically significant difference. Grey and White MTA presented high levels of clinical and radiographic success. Although the present study showed evidence of a very good biologic response with both types of MTA, Grey MTA showed significantly higher number of dentine bridge formation than White MTA. Copyright © 2010 Elsevier Ltd. All rights reserved.

Heavy metals in human teeth dentine: A bio-indicator of metals exposure and environmental pollution.

PubMed

Asaduzzaman, Khandoker; Khandaker, Mayeen Uddin; Binti Baharudin, Nurul Atiqah; Amin, Yusoff Bin Mohd; Farook, Mohideen Salihu; Bradley, D A; Mahmoud, Okba

2017-06-01

With rapid urbanization and large-scale industrial activities, modern human populations are being increasingly subjected to chronic environmental heavy metal exposures. Elemental uptake in tooth dentine is a bioindicator, the uptake occurring during the formation and mineralization processes, stored to large extent over periods of many years. The uptake includes essential elements, most typically geogenic dietary sources, as well as non-essential elements arising through environmental insults. In this study, with the help of the Dental Faculty of the University of Malaya, a total of 50 separate human teeth were collected from dental patients of various ethnicity, age, gender, occupation, dietary habit, residency, etc. Analysis was conducted using inductively coupled plasma-mass spectrometry (ICP-MS), most samples indicating the presence of the following trace elements, placed in order of concentration, from least to greatest: As, Mn, Ba, Cu, Cr, Pb, Zn, Hg, Sb, Al, Sr, Sn. The concentrations have been observed to increase with age. Among the ethnic groups, the teeth of ethnic Chinese showed marginally greater metal concentrations than those of the Indians and Malays, the teeth dentine of females generally showing greater concentrations than that of males. Greater concentrations of Hg, Cu and Sn were found in molars while Pb, Sr, Sb and Zn were present in greater concentrations in incisors. With the elevated concentration levels of heavy metals in tooth dentine reflecting pollution from industrial emissions and urbanization, it is evident that human tooth dentine can provide chronological information on exposure, representing a reliable bio-indicator of environmental pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Morphologic study of the maxillary molars. Part II: Internal anatomy.

PubMed

Pécora, J D; Woelfel, J B; Sousa Neto, M D; Issa, E P

1992-01-01

The internal anatomy of three hundred and seventy (370) decalcified and cleared human maxillary molars was studied. Seventy-five percent of the first molars, 58% of the second molars and 68% of the third molars studied presented three (3) root canals and 25% of the first molars, 42% of the second molars and 32% of the third molars presented four (4) root canals. The authors observed that the incidence of two root canals in the mesiobuccal root was higher in second maxillary molars than in first maxillary molars.

Maxillary sinus floor extension and posterior tooth inclination in adolescent patients with Class II Division 1 malocclusion treated with maxillary first molar extractions.

PubMed

Livas, Christos; Halazonetis, Demetrios J; Booij, Johan Willem; Pandis, Nikolaos; Tu, Yu-Kang; Katsaros, Christos

2013-04-01

Our objective was to investigate potential associations between maxillary sinus floor extension and inclination of maxillary second premolars and second molars in patients with Class II Division 1 malocclusion whose orthodontic treatment included maxillary first molar extractions. The records of 37 patients (18 boys, 19 girls; mean age, 13.2 years; SD, 1.62 years) treated between 1998 and 2004 by 1 orthodontist with full Begg appliances were used in this study. Inclusion criteria were white patients with Class II Division 1 malocclusion, sagittal overjet of ≥4 mm, treatment plan including extraction of the maxillary first permanent molars, no missing teeth, and no agenesis. Maxillary posterior tooth inclination and lower maxillary sinus area in relation to the palatal plane were measured on lateral cephalograms at 3 time points: at the start and end of treatment, and on average 2.5 years posttreatment. Data were analyzed for the second premolar and second molar inclinations by using mixed linear models. The analysis showed that the second molar inclination angle decreased by 7° after orthodontic treatment, compared with pretreatment values, and by 11.5° at the latest follow-up, compared with pretreatment. There was evidence that maxillary sinus volume was negatively correlated with second molar inclination angle; the greater the volume, the smaller the inclination angle. For premolars, inclination increased by 15.4° after orthodontic treatment compared with pretreatment, and by 8.1° at the latest follow-up compared with baseline. The volume of the maxillary sinus was not associated with premolar inclination. We found evidence of an association between maxillary second molar inclination and surface area of the lower sinus in patients treated with maxillary first molar extractions. Clinicians who undertake such an extraction scheme in Class II patients should be aware of this potential association and consider appropriate biomechanics to control root uprighting. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Concentrations of selected essential and non-essential elements in arctic fox (Alopex lagopus) and wolverines (Gulo gulo) from the Canadian Arctic.

PubMed

Hoekstra, P F; Braune, B M; Elkin, B; Armstrong, F A J; Muir, D C G

2003-06-20

Arctic fox (Alopex lagopus) and wolverine (Gulo gulo) tissues were collected in the Canadian Arctic from 1998 to 2001 and analyzed for various essential and non-essential elements. Several elements (Ag, Al, As, B, Ba, Be, Co, Cr, Mo, Ni, Sb, Sn, Sr, Tl, U and V) were near or below the detection limits in >95% arctic fox and wolverine samples. Concentrations of Cd, Cu, Fe, total Hg (THg), Mn, Pb, Se and Zn were quantifiable in >50% of the samples analyzed and reported herein. Hepatic elemental concentrations were not significantly different among arctic foxes collected at Ulukhaqtuuq (Holman), NT (n=13) and Arviat, NU (n=50), but were significantly greater than concentrations found in wolverine liver from Kugluktuk (Coppermine), NU (n=12). The mean (+/-1 S.E.) concentrations of Cd in kidney were also significantly greater in arctic fox (1.08+/-0.19 microg g(-1) wet wt.) than wolverine (0.67+/-0.18 microg g(-1) wet wt.). However, mean hepatic Cu concentrations (Ulukhaqtuuq: 5.5+/-0.64; Arviat: 7.1+/-0.49 microg g(-1) wet wt.) in arctic foxes were significantly lower than in wolverines (32+/-3.3 microg g(-1) wet wt.). Hepatic total Hg (THg) concentrations in arctic fox from this study were not significantly different from specimens collected in 1973, suggesting that THg concentrations have not changed dramatically over the past 30 years. The mono-methylmercury (MeHg) concentrations in selected (n=10) arctic fox liver samples from Arviat (0.14+/-0.07 microg g(-1) wet wt.) comprised 14% of THg. While the molar concentrations of THg were correlated with Se in arctic foxes and wolverines, the hepatic Hg/Se molar ratios were consistently lower than unity; suggesting that Se-mediated detoxification pathways of Hg are not overwhelmed at current exposure.

Method of recovering hazardous waste from phenolic resin filters

DOEpatents

Meikrantz, David H.; Bourne, Gary L.; McFee, John N.; Burdge, Bradley G.; McConnell, Jr., John W.

1991-01-01

The invention is a process for the recovery of hazardous wastes such as heavy metals and radioactive elements from phenolic resin filter by a circulating a solution of 8 to 16 molar nitric acid at a temperature of 110 to 190 degrees F. through the filter. The hot solution dissolves the filter material and releases the hazardous material so that it can be recovered or treated for long term storage in an environmentally safe manner.

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes.

PubMed

Chandra, Sulekh; Gautam, Seema; Rajor, Hament Kumar; Bhatia, Rohit

2015-02-25

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, (1)H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand. Copyright © 2014 Elsevier B.V. All rights reserved.

Glass ionomer ART sealant and fluoride-releasing resin sealant in fissure caries prevention – results from a randomized clinical trial

PubMed Central

2014-01-01

Background The relative performance of ART sealant and fluoride-releasing resin sealant in preventing fissure caries in permanent molars was compared in a randomized clinical trial conducted in southern China (ClinicalTrials.gov NCT01829334). Methods After obtaining ethical approval, healthy schoolchildren who had permanent first molars with occlusal fissures which were sound but deep or presented with only incipient caries were recruited for the study. Included molars were randomly allocated into one of four parallel study groups in units of left/right teeth per mouth. Two of the four groups adopted the methods of ART or fluoride-releasing resin sealant placement while the other two groups adopted the topical fluoride application methods. Fissure status of the molars in each group was evaluated every 6 months. Development of dentine caries and sealant retention over 24 months in the molars in the two sealant-using groups was compared in this report. Outcome on cost-effectiveness of all four groups over 36 months will be reported elsewhere. Results At baseline, a total of 280 children (383 molars) with mean age 7.8 years were involved for the two sealant groups. After 24 months, 261 children (357 molars) were followed. Proportions of molars with dentine caries were 7.3% and 3.9% in the ART sealant and fluoride-releasing resin sealant groups, respectively (chi-square test, p = 0.171). Life-table survival analysis showed that sealant retention (full and partial) rate over 24 months for the resin sealant (73%) was significantly higher than that (50%) for the ART sealant (p < 0.001). Molar survival (no development of dentine caries) rates in the ART sealant (93%) and fluoride-releasing resin sealant (96%) groups were not significantly different (p = 0.169). Multilevel logistic regression (GEE modeling) accounting for the effects of data clustering and confounding factors confirmed this finding. Conclusions Though the retention of fluoride-releasing resin sealant was better than that of the ART sealant, their effectiveness in preventing fissure caries in permanent molars did not differ significantly over 24 months. ART sealants could be a good alternative when and where resources for resin sealant placement are not readily available. PMID:24886444

Molar distalization with pendulum appliances in the mixed dentition: effects on the position of unerupted canines and premolars.

PubMed

Kinzinger, Gero S M; Wehrbein, Heinrich; Gross, Ulrich; Diedrich, Peter R

2006-03-01

The pendulum appliance allows for rapid molar distalization without the need for patient compliance. Its efficiency has been confirmed in a number of clinical studies. However, the potential interactions and positional changes between the deciduous molars used for dental anchorage and the erupted and unerupted permanent teeth have yet to be clarified when this appliance is used for molar distalization in the mixed dentition. Twenty-nine patients in the mixed dentition each received a modified pendulum appliance with a distal screw and a preactivated pendulum spring for bilateral distalization of the maxillary molars. The patients were divided into 4 groups based on dentition stages: patient group 1 (PG 1, n = 10) was in the early mixed dentition; patients had resorption of the distal root areas of the deciduous molars being used for dental anchorage, and the unerupted premolars were located at the distal margin of the deciduous molar root region. Based on radiographs taken before placement of the pendulum appliance, patient group 2 (PG 2, n = 10) was diagnosed as having a central location of the unerupted premolars. In the third group (PG 3, n = 4), the first premolars were already erupted and could be integrated into the dental anchorage, but the canines were not yet erupted. In the fourth group (PG 4, n = 5), the first premolars and both canines were fully erupted. Statistical analysis of the measured results showed significant differences in the side effects between PG 1 and PG 2. In patients being treated with pendulum appliances, the anchorage quality of the deciduous molars that were already partially resorbed in the distal root area was comparatively reduced. Consequently, the mesial drift of the deciduous molars and incisors was increased, without impairing the extent and quality of the molar distalization. Anchorage loss in the supporting area had no direct impact on the sagittal position of the unerupted premolars in the early mixed dentition. If permanent teeth have already started to erupt in the supporting area, additional space restrictions should be avoided in patients with critical topography, especially if there is little space for the unerupted canines. At this stage of the mixed dentition, premolar extraction or augmentation of the supporting area with extraoral headgear offers a therapeutic alternative to intraoral distalization appliances with exclusively dental anchorage.

Saving the 2nd Molar from the 3rd Is it Really the Guilt of the Tilt?

PubMed Central

Yadav, Pankaj; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

2016-01-01

Introduction Clinicians often relate the distal caries in second molars to angulated third molars, which if left undetected can lead to gross decay that may further require removal of the tooth. Due to this fact, many third molars are advised for prophylactic removal to prevent decay in the second molar. But this approach would only be justified when the incidence of decay/loss of second molar due to third molar are reasonably high. We sought to determine incidence of caries experience and also sequel extraction in second molars associated with the third molars. Aim The study was conducted to answer the basic question that whether the incidence of caries and subsequent extraction of second molar due to angulated third molars is high enough to justify the prophylactic removal of third molar or not. Materials and Methods This study was conducted on radiographic records of 1187 patients. The effect of tilted third molar on the second molar was measured in relation with three parameters namely level & position of third molar with respect to second molar and the distribution among arches. Results The results indicated that out of total number of teeth examined only 5.4% of maxillary and 9.6% of mandibular second molars were affected by tilted third molars. Further, only 2.2% of mandibular and 2.9% of maxillary second molars were indicated for extraction. The data was statistically insignificant. Conclusion It was concluded that distal caries in second molars is not very common. It may be present in some cases of third molar impactions and prophylactic removal of these impacted teeth may not be considered appropriate. PMID:27437353

Stress and strain distribution in demineralized enamel: A micro-CT based finite element study.

PubMed

Neves, Aline Almeida; Coutinho, Eduardo; Alves, Haimon Diniz Lopes; de Assis, Joaquim Teixeira

2015-10-01

Physiological oral mechanical forces may play a role on the progression of enamel carious lesions to cavitation. Thus, the aim of this study was to describe, by 3D finite element analysis, stress, and strain patterns in sound and carious enamel after a simulated occlusal load. Micro-CT based models were created and meshed with tetrahedral elements (based on an extracted third molar), namely: a sound (ST) and a carious tooth (CT). For the CT, enamel material properties were assigned according to the micro-CT gray values. Below the threshold corresponding to the enamel lesion (2.5 g/cm(3) ) lower and isotropic elastic modulus was assigned (E = 18 GPa against E1  = 80 GPa, E2  = E3  = 20 GPa for sound enamel). Both models were imported into a FE solver where boundary conditions were assigned and a pressure load (500 MPa) was applied at the occlusal surface. A linear static analysis was performed, considering anisotropy in sound enamel. ST showed a more efficient transfer of maximum principal stress from enamel to the dentin layer, while for the CT, enamel layer was subjected to higher and concentrated loads. Maximum principal strain distributions were seen at the carious enamel surface, especially at the central fossa, correlating to the enamel cavity seen at the original micro-CT model. It is possible to conclude that demineralized enamel compromises appropriate stress transfer from enamel to dentin, contributing to the odds of fracture and cavitation. Enamel fracture over a dentin lesion may happen as one of the normal pathways to caries progression and may act as a confounding factor during clinical diagnostic decisions. © 2015 Wiley Periodicals, Inc.

Influence of implant number on the biomechanical behaviour of mandibular implant-retained/supported overdentures: a three-dimensional finite element analysis.

PubMed

Liu, Jingyin; Pan, Shaoxia; Dong, Jing; Mo, Zhongjun; Fan, Yubo; Feng, Hailan

2013-03-01

The aim of this study was to evaluate strain distribution in peri-implant bone, stress in the abutments and denture stability of mandibular overdentures anchored by different numbers of implants under different loading conditions, through three-dimensional finite element analysis (3D FEA). Four 3D finite element models of mandibular overdentures were established, using between one and four Straumann implants with Locator attachments. Three types of load were applied to the overdenture in each model: 100N vertical and inclined loads on the left first molar and a 100N vertical load on the lower incisors. The biomechanical behaviours of peri-implant bone, implants, abutments and overdentures were recorded. Under vertical load on the lower incisors, the single-implant overdenture rotated over the implant from side to side, and no obvious increase of strain was found in peri-implant bone. Under the same loading conditions, the two-implant-retained overdenture showed more apparent rotation around the fulcrum line passing through the two implants, and the maximum equivalent stress in the abutments was higher than in the other models. In the three-implant-supported overdenture, no strain concentration was found in cortical bone around the middle implant under three loading conditions. Single-implant-retained mandibular overdentures do not show damaging strain concentration in the bone around the only implant and may be a cost-effective treatment option for edentulous patients. A third implant can be placed between the original two when patients rehabilitated by two-implant overdentures report constant and obvious denture rotation around the fulcrum line. Copyright © 2012 Elsevier Ltd. All rights reserved.

Schaeffler-Type Phase Diagram of Ti-Based Alloys

NASA Astrophysics Data System (ADS)

Ishida, K.

2017-10-01

The α(hcp)/β(bcc) phase equilibria of Ti-based multi-component alloys can be described by a Schaeffler-type diagram, where Al and Mo equivalents (Aleq and Moeq) are used. Aleq is thermodynamically defined by the ratio of partial molar free energy changes transfer of one mole of each α forming element and Al from a dilute solution of α to β phases, while Moeq is also deduced by similar thermodynamic quantities of β forming element and Mo. Aleq and Moeq for 40 alloying elements are estimated from the thermodynamic parameters assessed by Kaufman and Murray. It is shown that three types of Ti alloys, i.e., α and near α, α+β, and β alloys, can be exactly classified using Aleq and Moeq. The Ms and β transus temperatures can also be predicted by Aleq and Moeq. The proposed Aleq and Moeq are very useful for alloy design, heat treatment, and microstructural evolution of Ti-based alloys.

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes

PubMed Central

2014-01-01

Aims Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Material and methods Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. Results The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Conclusions Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well. PMID:25208969

Micro-computed Tomographic Analysis of Mandibular Second Molars with C-shaped Root Canals.

PubMed

Amoroso-Silva, Pablo Andrés; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro; Gutmann, James L; del Carpio-Perochena, Aldo; Bramante, Clovis Monteiro; de Moraes, Ivaldo Gomes

2015-06-01

The goal of the present study was to evaluate the morphometric aspects of the internal anatomy of the root canal system of mandibular second molars with C-shaped canals. Fifty-two extracted second mandibular molars with C-shaped canals, fused roots, and radicular grooves were selected from a Brazilian population. The samples were scanned with a micro-computed tomographic scanner at a voxel size of 19.6 μm. The root canal cross sections were recorded as C1, C2, C3, and C4 root canal configurations according to the modified Melton classification. Morphometric parameters, including the major and minor diameters of the root canals, the aspect ratio, the roundness, and the tridimensional configuration (merging, symmetric, and asymmetric), were evaluated. The 3-dimensional reconstruction images of the teeth indicated an even distribution within the sample. The analysis of the prevalence of the different cross-sectional configurations of the C-shaped molars revealed that these were predominantly of the C4 and C3 configurations (1 mm from the apex) and the C1 and C2 configurations in the cervical third. According to the morphometric parameters, the C1 and the distal aspect of the C2 configurations exhibited the lowest roundness values and higher values for the area, major diameter, and aspect ratio in the apical third. Mandibular molars with C-shaped root canals exhibited similar distributions of symmetric, asymmetric, and merging type canals. The C1 configuration and the distal aspect of the C2 configuration exhibited the highest area values, low roundness values, and large apical diameters. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Maxwell displacement current allows to study structural changes of gramicidin A in monolayers at the air-water interface.

PubMed

Vitovic, Pavol; Weis, Martin; Tomcík, Pavol; Cirák, Július; Hianik, Tibor

2007-05-01

We applied methods of measurement Maxwell displacement current (MDC) pressure-area isotherms and dipole potential for analysis of the properties of gramicidin A (gA) and mixed gA/DMPC monolayers at an air-water interface. The MDC method allowed us to observe the kinetics of formation of secondary structure of gA in monolayers at an air-water interface. We showed, that secondary structure starts to form at rather low area per molecule at which gA monolayers are in gaseous state. Changes of the MDC during compression can be attributed to the reorientation of dipole moments in a gA double helix at area 7 nm(2)/molecule, followed by the formation of intertwined double helix of gA. The properties of gA in mixed monolayers depend on the molar fraction of gA/DMPC. At higher molar fractions of gA (around 0.5) the shape of the changes of dipole moment of mixed monolayer was similar to that for pure gA. The analysis of excess free energy in a gel (18( ) degrees C) and in a liquid-crystalline phase (28( ) degrees C) allowed us to show influence of the monolayer structural state on the interaction between gA and the phospholipids. In a gel state and at the gA/DMPC molar ratio below 0.17 the aggregates of gA were formed, while above this molar ratio gA interacts favorably with DMPC. In contrast, for DMPC in a liquid-crystalline state aggregation of gA was observed for all molar fractions studied. The effect of formation ordered structures between gA and DMPC is more pronounced at low temperatures.

Three-dimensional quantitative analysis of adhesive remnants and enamel loss resulting from debonding orthodontic molar tubes.

PubMed

Janiszewska-Olszowska, Joanna; Tandecka, Katarzyna; Szatkiewicz, Tomasz; Sporniak-Tutak, Katarzyna; Grocholewicz, Katarzyna

2014-09-10

Presenting a new method for direct, quantitative analysis of enamel surface. Measurement of adhesive remnants and enamel loss resulting from debonding molar tubes. Buccal surfaces of fifteen extracted human molars were directly scanned with an optic blue-light 3D scanner to the nearest 2 μm. After 20 s etching molar tubes were bonded and after 24 h storing in 0.9% saline - debonded. Then 3D scanning was repeated. Superimposition and comparison were proceeded and shape alterations of the entire objects were analyzed using specialized computer software. Residual adhesive heights as well as enamel loss depths have been obtained for the entire buccal surfaces. Residual adhesive volume and enamel loss volume have been calculated for every tooth. The maximum height of adhesive remaining on enamel surface was 0.76 mm and the volume on particular teeth ranged from 0.047 mm3 to 4.16 mm3. The median adhesive remnant volume was 0.988 mm3. Mean depths of enamel loss for particular teeth ranged from 0.0076 mm to 0.0416 mm. Highest maximum depth of enamel loss was 0.207 mm. Median volume of enamel loss was 0.104 mm3 and maximum volume was 1.484 mm3. Blue-light 3D scanning is able to provide direct precise scans of the enamel surface, which can be superimposed in order to calculate shape alterations. Debonding molar tubes leaves a certain amount of adhesive remnants on the enamel, however the interface fracture pattern varies for particular teeth and areas of enamel loss are present as well.

Third molar removal and its impact on quality of life: systematic review and meta-analysis.

PubMed

Duarte-Rodrigues, Lucas; Miranda, Ednele Fabyene Primo; Souza, Taiane Oliveira; de Paiva, Haroldo Neves; Falci, Saulo Gabriel Moreira; Galvão, Endi Lanza

2018-05-24

The purpose of this systematic review was to assess the impact of third molar removal on patient's quality of life. To address the study purpose, investigators designed and implemented a systematic review. The primary outcome variable was the quality of life after third molar extraction. An electronic search was conducted through March, 2017, on the PUBMED, Virtual Health Library (VHL), Web of Science, and OVID, to identify relevant literatures. Research studies (randomized or non-randomized clinical trials) were included that evaluated the quality of life in individuals before and after third molar extraction, using validated measures of oral health-related quality of life with quantitative approach, besides procedures performed under local anesthesia. The R software was used to measure the mean difference on the quality of life between the preoperative period and follow-up days. A total of 1141 studies were identified. Of this total, 13 articles were selected in the present systematic review, of which six studies were included in the meta-analysis. All of these 13 articles used the OHIP-14, and 4 of this 13 used OHQoLUK-16 to evaluate the quality of life. Regarding quality assessment, four of the 13 included studies in this review received a maximum score of 9 points, according to the Newcastle-Ottawa (NOS). The OHIP-14 mean score on the first postoperative day was 17.57 (95% CI 11.84-23.30, I 2  = 96%) higher than the preoperative period. On the seventh postoperative day, the quality of life assessed by OHIP-14 got worse again. This systematic review revealed that the highest negative impact on quality of life of individuals submitted to third molar surgery was observed on the first postoperative day, decreasing over the follow-up period.

Infection, Alveolar Osteitis, and Adverse Effects Using Metronidazole in Healthy Patients Undergoing Third Molar Surgery: A Meta-analysis.

PubMed

Isiordia-Espinoza, Mario Alberto; Aragon-Martinez, Othoniel H; Bollogna-Molina, Ronell E; Alonso-Castro, Ángel J

2018-06-01

The aim of this systematic review and meta-analysis was to evaluate the risk of surgical infection, alveolar osteitis, and adverse effects using systemic metronidazole in comparison with placebo in healthy patients undergoing third molar surgery. The eligible reports were identified from diverse science sources. Clinical trials meeting the inclusion and exclusion criteria and an acceptable Oxford Quality Score were included in this study. The evaluation of risk was done using the Risk Reduction Calculator and Review Manager 5.3., from the Cochrane Library. A significant risk reduction was assumed when the upper limit of the 95% confidence intervals was <1 and the lower limit did not cross zero (negative number) alongside a p value of <0.05 for the overall test. Data of 667 patients from five clinical trials were used for the assessment of risk. Our analysis showed no reduction of the risk of infection or dry socket in patients receiving metronidazole compared to whom took placebo. Meanwhile, the adverse effects did not exhibit a difference between the studied groups. The routine use of systemic metronidazole to prevent surgical site infection and/or dry socket in healthy patients undergoing third molar surgery is not recommended.

Digitized morphometric analysis of dental pulp of permanent mandibular second molar for age estimation of Davangere population.

PubMed

Kumar, Nerella Narendra; Panchaksharappa, Mamatha Gowda; Annigeri, Rajeshwari G

2016-04-01

The aim of the present study is to estimate the age of Davangere population by evaluating the pulp to tooth area ratio (PTR) by using digitized intraoral periapical radiographs of permanent mandibular second molar. 400 intraoral periapical radiograph (IOPA) of permanent mandibular 2nd molar of both the sexes aged 14-60 years were used. Digital camera was used to image the radiographs. Images were computed and PTR was calculated by AUTOCAD software. Intra and Inter observer variability was also assessed. Regression analysis was used to estimate the age of an individual by taking PTR as dependent variable. The mean PTR of males and females was 0.10 ± 0.02 and 0.09 ± 0.02 respectively. Negative correlation was observed, when age was compared with PTR {r = -0.441, -0.406 & -0.419 among males, females and total subjects (p < 0.001)}. Regression analysis showed a Standard Error of Estimate (SEE) of 12 years. The Kappa coefficient value for the intra and inter examiner variability was 0.85 & 0.83 respectively. Our results showed that permanent mandibular 2(nd) molar can be taken as an index tooth for estimating the age of the adults using digitized periapical radiograph and AUTOCAD software. Also high differences were observed between estimated and chronological age of 12 years which is not in the acceptable range. But it provides a new window for research in the forensic sciences in estimating the adult age. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Replacement of a first molar and 3 second molars by the mesial inclination of 4 impacted third molars in an adult with a Class II Division 1 malocclusion.

PubMed

Tomonari, Hiroshi; Yagi, Takakazu; Kuninori, Takaharu; Ikemori, Takahiro; Miyawaki, Shouichi

2015-06-01

This case report presents the successful replacement of 1 first molar and 3 second molars by the mesial inclination of 4 impacted third molars. A woman, 23 years 6 months old, had a chief complaint of crowding of her anterior teeth and linguoclination of a second molar on the left side. The panoramic radiographic images showed that the maxillary and mandibular third molars on both sides were impacted. Root resorption on the distal surfaces of the maxillary second molars was suspected. The patient was given a diagnosis of Angle Class II Division 1 malocclusion with severe crowding of the anterior teeth and 4 impacted third molars. After we extracted the treated maxillary second premolars and the second molars on both sides, the treated mandibular second premolar and the second molar on the left side, and the root canal-filled mandibular first molar on the right side, the 4 impacted third molars were uprighted and formed part of the posterior functional occlusion. The total active treatment period was 39 months. The maxillary and mandibular third molars on both sides successfully replaced the first and second molars. The replacement of a damaged molar by an impacted third molar is a useful treatment option for using sound teeth. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Efficacy of clinical and radiological methods to identify second mesiobuccal canals in maxillary first molars.

PubMed

Abuabara, Allan; Baratto-Filho, Flares; Aguiar Anele, Juliana; Leonardi, Denise Piotto; Sousa-Neto, Manoel Damião

2013-01-01

The success of endodontic treatment depends on the identification of all root canals. Technological advances have facilitated this process as well as the assessment of internal anatomical variations. The aim of this study was to compare the efficacy of clinical and radiological methods in locating second mesiobuccal canals (MB2) in maxillary first molars. Fifty patients referred for analysis; access and clinical analysis; cone-beam endodontic treatment of their maxillary first molars were submitted to the following assessments: analysis; access and clinical analysis; cone-beam computed tomography (CBCT); post-CBCT clinical analysis; clinical analysis using an operating microscope; and clinical analysis after Start X ultrasonic inserts in teeth with negative results in all previous analyses. Periapical radiographic analysis revealed the presence of MB2 in four (8%) teeth, clinical analysis in 25 (50%), CBCT analysis in 27 (54%) and clinical analysis following CBCT and using an operating microscope in 27 (54%) and 29 (58%) teeth, respectively. The use of Start X ultrasonic inserts allowed one to detect two additional teeth with MB2 (62%). According to Vertucci's classification 48% of the mesiobuccal canals found were type I, 28% type II, 18% type IV and 6% type V. Statistical analysis showed no significant differences (p > 0.5) in the ability of CBCT to detect MB2 canals when compared with clinical assessment with or without an operating microscope. A significant difference (p < 0.001)was found only between periapical radiography and clinical/CBCT evaluations. Combined use of different methods increased the detection ofthe second canal in MB roots, but without statistical difference among CBCT, operating microscope, Start X and clinical analysis.

Treatment effects of the Forsus Fatigue Resistant Device used with miniscrew anchorage.

PubMed

Aslan, Belma I; Kucukkaraca, Ebru; Turkoz, Cagri; Dincer, Mufide

2014-01-01

To evaluate the dentofacial effects of the Forsus Fatigue Resistant Device (FRD) used with miniscrew anchorage (FRDMS) and compare them with those of conventional FRD and an untreated Class II control group. The sample consisted of 48 Class II subjects. Sixteen patients (13.68 ± 1.09 years of age) were treated with FRDMS, whereas 17 subjects (14.64 ± 1.56 years of age) were treated with only FRD. Also, a control sample of 15 untreated Class II subjects (14.13 ± 1.50 years of age) was constructed. Angular and linear measurements were made on 96 lateral cephalograms. Paired t, one-way analysis of variance, and Tukey tests were used for statistical analysis. Class I molar relationship and overjet correction were achieved in an average period of 6.5 ± 1.97 and 5.5 ± 1.80 months in the FRDMS and FRD groups, respectively. No skeletal effect was determined in both treatment groups. Greater overbite correction was found in the FRD group. Retrusion and extrusion of maxillary incisors, distalization of maxillary molars, and extrusion of mandibular molars were significant in both treatment groups. Labial tipping of mandibular incisors was significantly greater in the FRD group than in the FRDMS group. Overjet and molar correction was totally dentoalveolar. Unfavorable labial tipping of mandibular incisors was effectively minimized with the usage of miniscrews.

Retained asymptomatic third molars and risk for second molar pathology.

PubMed

Nunn, M E; Fish, M D; Garcia, R I; Kaye, E K; Figueroa, R; Gohel, A; Ito, M; Lee, H J; Williams, D E; Miyamoto, T

2013-12-01

Prophylactic extraction of unerupted asymptomatic third molars is the most common oral surgery procedure in the United States. However, limited evidence exists to justify its costs and associated morbidity. We analyzed data collected over 25 years from 416 adult men enrolled in the Veterans Affairs Dental Longitudinal Study to evaluate the association of retained asymptomatic third molars with risk of adjacent second molar pathology (caries and/or periodontitis), based on third molar status (i.e., absent, erupted, or unerupted). Unerupted molars were further categorized as either "soft tissue" or "bony" impacted. We found that the lowest prevalence and incidence of second molar pathology occurred when the adjacent third molar was absent. The presence of a third molar that was soft tissue impacted increased the risk of incident second molar pathology 4.88-fold (95% confidence interval: 2.62, 9.08). Having an erupted or "bony" impacted third molar increased the risk of incident second molar pathology by 1.74 (95% confidence interval: 1.34, 2.25) and 2.16 (95% confidence interval: 1.56, 2.99), respectively. The retention of third molars is associated with increased risk of second molar pathology in middle-aged and older adult men.

Retained Asymptomatic Third Molars and Risk for Second Molar Pathology

PubMed Central

Nunn, M.E.; Fish, M.D.; Garcia, R.I.; Kaye, E.K.; Figueroa, R.; Gohel, A.; Ito, M.; Lee, H.J.; Williams, D.E.; Miyamoto, T.

2013-01-01

Prophylactic extraction of unerupted asymptomatic third molars is the most common oral surgery procedure in the United States. However, limited evidence exists to justify its costs and associated morbidity. We analyzed data collected over 25 years from 416 adult men enrolled in the Veterans Affairs Dental Longitudinal Study to evaluate the association of retained asymptomatic third molars with risk of adjacent second molar pathology (caries and/or periodontitis), based on third molar status (i.e., absent, erupted, or unerupted). Unerupted molars were further categorized as either “soft tissue” or “bony” impacted. We found that the lowest prevalence and incidence of second molar pathology occurred when the adjacent third molar was absent. The presence of a third molar that was soft tissue impacted increased the risk of incident second molar pathology 4.88-fold (95% confidence interval: 2.62, 9.08). Having an erupted or “bony” impacted third molar increased the risk of incident second molar pathology by 1.74 (95% confidence interval: 1.34, 2.25) and 2.16 (95% confidence interval: 1.56, 2.99), respectively. The retention of third molars is associated with increased risk of second molar pathology in middle-aged and older adult men. PMID:24132082

Theory of chromatography of partially cyclic polymers: Tadpole-type and manacle-type macromolecules.

PubMed

Vakhrushev, Andrey V; Gorbunov, Alexei A

2016-02-12

A theory of chromatography is developed for partially cyclic polymers of tadpole- and manacle-shaped topological structures. We present exact equations for the distribution coefficient K at different adsorption interactions; simpler approximate formulae are also derived, relevant to the conditions of size-exclusion, adsorption, and critical chromatography. Theoretical chromatograms of heterogeneous partially cyclic polymers are simulated, and conditions for good separation by topology are predicted. According to the theory, an effective SEC-radius of tadpoles and manacles is mostly determined by the molar mass M, and by the linear-cyclic composition. In the interactive chromatography, the effect of molecular topology on the retention becomes significant. At the critical interaction point, partial dependences K(Mlin) and K(Mring) are qualitatively different: while being almost independent of Mlin, K increases with Mring. This behavior could be realized in critical chromatography-for separation of partially cyclic polymers by the number and molar mass of cyclic elements. Copyright © 2015 Elsevier B.V. All rights reserved.

Interfacial profiles in fluid/liquid systems: a description based on the storing of elastic energy.

PubMed

Castellanos-Suárez, Aly J; Toro-Mendoza, Jhoan; García-Sucre, Máximo

2011-06-01

An analytical expression for the interfacial energy is found by solving a Poisson equation and assuming a Boltzmann distribution of volume elements forming the fluid/liquid system. Interfacial phenomena are treated as a result of the response of a liquid when it makes contact with other fluid phase, in order to reach thermal and mechanical equilibrium. This model gives a quantitative description of the interface, obtaining values for its molar, force and energy density profiles. Also, our model allows the determination of the proportion of the fluids present in the interfacial zone, the values of interfacial tension and thickness. In the case of water+n-alkanes systems, the tensions are in agreement with the behavior shown by the experimental data. Finally, the values for interfacial thickness predicted from molar density profiles are lower than the range of influence of the elastic energy and elastic field. Copyright © 2011 Elsevier Inc. All rights reserved.

Spectroscopic and physical measurements on charge-transfer complexes: Interactions between norfloxacin and ciprofloxacin drugs with picric acid and 3,5-dinitrobenzoic acid acceptors

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Elfalaky, A.; Elesh, Eman

2011-03-01

Charge-transfer complexes formed between norfloxacin (nor) or ciprofloxacin (cip) drugs as donors with picric acid (PA) and/or 3,5-dinitrobenzoic acid (DNB) as π-acceptors have been studied spectrophotometrically in methanol solvent at room temperature. The results indicated the formation of CT-complexes with molar ratio1:1 between donor and acceptor at maximum CT-bands. In the terms of formation constant ( KCT), molar extinction coefficient ( ɛCT), standard free energy (Δ Go), oscillator strength ( f), transition dipole moment (μ), resonance energy ( RN) and ionization potential ( ID) were estimated. IR, H NMR, UV-Vis techniques, elemental analyses (CHN) and TG-DTG investigations were used to characterize the structural of charge-transfer complexes. It indicates that the CT interaction was associated with a proton migration from each acceptor to nor or cip donors which followed by appearing intermolecular hydrogen bond. In addition, X-ray investigation was carried out to scrutinize the crystal structure of the resulted CT-complexes.

Spectroscopic and thermal investigations of charge-transfer complexes formed between sulfadoxine drug and different types of acceptors

NASA Astrophysics Data System (ADS)

Refat, Moamen S.

2011-01-01

Charge-transfer reactions between sulfadoxine (SDOX) as a donor with iodine (I 2), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil (CHL) and picric acid (PA) have been studied in solid and solution forms. The stoichiometry of all complexes was found to be 1:1 by molar ratio method between donor and acceptor at a CT-band absorption bands. The data are discussed in terms of formation constant ( KCT), molar extinction coefficient ( ɛCT), standard free energy (Δ Go), oscillator strength (ƒ), transition dipole moment ( μ), resonance energy ( RN) and ionization potential ( ID). The results indicate that the formation constant ( KCT) for the complexes were shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents which were used. IR, 1H NMR and UV-Vis spectroscopic techniques, Elemental analyses (CHN) and TG-DTG investigation were used to characterize the four sulfadoxine charge-transfer complexes.

An implicit numerical model for multicomponent compressible two-phase flow in porous media

NASA Astrophysics Data System (ADS)

Zidane, Ali; Firoozabadi, Abbas

2015-11-01

We introduce a new implicit approach to model multicomponent compressible two-phase flow in porous media with species transfer between the phases. In the implicit discretization of the species transport equation in our formulation we calculate for the first time the derivative of the molar concentration of component i in phase α (cα, i) with respect to the total molar concentration (ci) under the conditions of a constant volume V and temperature T. The species transport equation is discretized by the finite volume (FV) method. The fluxes are calculated based on powerful features of the mixed finite element (MFE) method which provides the pressure at grid-cell interfaces in addition to the pressure at the grid-cell center. The efficiency of the proposed model is demonstrated by comparing our results with three existing implicit compositional models. Our algorithm has low numerical dispersion despite the fact it is based on first-order space discretization. The proposed algorithm is very robust.

IR, 1H NMR, mass, XRD and TGA/DTA investigations on the ciprofloxacin/iodine charge-transfer complex.

PubMed

Refat, Moamen S; El-Hawary, W F; Moussa, Mohamed A A

2011-05-01

The charge-transfer complex (CTC) of ciprofloxacin drug (CIP) as a donor with iodine (I(2)) as a sigma acceptor has been studied spectrophotometrically in CHCl(3). At maximum absorption bands, the stoichiometry of CIP:iodine system was found to be 1:1 ratio according to molar ratio method. The essential spectroscopic data like formation constant (K(CT)), molar extinction coefficient (ɛ(CT)), standard free energy (ΔG°), oscillator strength (f), transition dipole moment (μ), resonance energy (R(N)) and ionization potential (I(D)) were estimated. The spectroscopic techniques such as IR, (1)H NMR, mass and UV-vis spectra and elemental analyses (CHN) as well as TG-DTG and DTA investigations were used to characterize the chelating behavior of CIP/iodine charge-transfer complex. The iodine CT interaction was associated with a presence of intermolecular hydrogen bond. The X-ray investigation was carried out to investigate the iodine doping in the synthetic CT complex. Copyright © 2011 Elsevier B.V. All rights reserved.

Doping optimization of polypyrrole with toluenesulfonic acid using Box-Behnken design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Syed Draman, Sarifah Fauziah; Daik, Rusli; El-Sheikh, Said M.

A three-level Box-Behnken design was employed in doping optimization of polypyrrole with toluenesulfonic acid (TSA-doped PPy). The material was synthesized via chemical oxidative polymerization using pyrrole, toluenesulfonic acid (TSA) and ammonium persulfate (APS) as monomer, dopant and oxidant, respectively. The critical factors selected for this study were concentration of dopant, molar ratio between dopant to monomer (pyrrole) and concentration of oxidant. Obtaining adequate doping level of TSA-doped PPy is crucial because it affects the charge carriers for doped PPy and usually be responsible for electronic mobility along polymeric chain. Furthermore, the doping level also affects other properties such as electricalmore » and thermal conductivity. Doping level was calculated using elemental analysis. SEM images shows that the prepared TSA-doped PPy particles are spherical in shape with the diameters of about. The range of nanoparticles size is around 80-100 nm. The statistical analysis based on a Box–Behnken design showed that 0.01 mol of TSA, 1:1 mole ratio TSA to pyrrole and 0.25 M APS were the optimum conditions for sufficient doping level.« less

A facile access to new diazepines derivatives: Spectral characterization and crystal structures of 7-(thiophene-2-yl)-5-(trifluoromethyl)-2,3-dihydro-1H-1,4-diazepine and 2-thiophene-4-trifluoromethyl-1,5-benzodiazepine

NASA Astrophysics Data System (ADS)

Ahumada, Guillermo; Carrillo, David; Manzur, Carolina; Fuentealba, Mauricio; Roisnel, Thierry; Hamon, Jean-René

2016-12-01

The one-pot double condensation reaction of 2-thenoyltrifluoroacetone (2-TTA) with ethylendiamine or o-phenylenediamine, in a 2:1 stoichiometric molar ratio, leads to the formation of 7-(thiophene-2-yl)-5-(trifluoromethyl)-2,3-dihydro-1H-1,4-diazepine 2 and 2-thiophene-4-trifluoromethyl-1,5-benzodiazepine 3, that were isolated in 56 and 53% yields, respectively. The bis(trifluoroacetamide)ethylene derivative 1 was also isolated in 32% yield as a side-product in the reaction of 2-TTA and ethylenediamine. Compounds 1-3 were fully characterized by elemental analysis, FT-IR and multinuclear (1H, 13C and 19F) NMR spectroscopy. In addition, their molecular identities and geometries have been authenticated by single-crystal X-ray diffraction analysis. The spectroscopic and structural data confirm that the 1,4-diazepine 2 and the 1,5-benzodiazepine 3 exist in the imine-enamine and diimine tautomeric forms, respectively, both in solution and in the solid-state.

Evaluation of enamel by scanning electron microscopy green LED associated to hydrogen peroxide 35% for dental bleaching

NASA Astrophysics Data System (ADS)

Monteiro, Juliana S. C.; de Oliveira, Susana C. P. S.; Zanin, Fátima A. A.; Santos, Gustavo M. P.; Sampaio, Fernando J. P.; Gomes Júnior, Rafael Araújo; Gesteira, Maria F. M.; Vannier-Santos, Marcos A.; Pinheiro, Antônio Luiz B.

2014-02-01

Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.

Ultrasound assisted synthesis, characterization and electrochemical study of a tetradentate oxovanadium diazomethine complex

NASA Astrophysics Data System (ADS)

Merzougui, Moufida; Ouari, Kamel; Weiss, Jean

2016-09-01

The oxovanadium (IV) complex ;VOL; of a tetradentate Schiff base ligand derived from the condensation of diaminoethane and 2-hydroxy-1-naphthaldehyde was efficiently prepared via ultrasound irradiation and the template effect of VO(acac)2. The resulting product was characterized by elemental analysis, infrared, electronic absorption and molar conductance measurement. Single X-ray structure analysis showed that the complex is a monomeric five-coordinate with a distorted square pyramidal geometry. It crystallizes in monoclinic system having unit cell parameters a = 8.3960 (5) Å; b = 12.5533 (8) Å and c = 18.7804 (11) Å; α = γ = 90°; β = 104.843°(2), with P 21/c space group. Cyclic voltammetry of the complex, carried out on a glassy carbon (GC) electrode in DMF, showed reversible cyclic voltammograms response in the potential range 0.15-0.60 V involving a single electron redox wave VV/VIV, the diffusion coefficient is determinedusing GC rotating disk electrode. The Levich plot Ilim = f(ω1/2), was used to calculate the diffusion-convection controlled currents.

Charge transfer complex between 2,3-diaminopyridine with chloranilic acid. Synthesis, characterization and DFT, TD-DFT computational studies

NASA Astrophysics Data System (ADS)

Al-Ahmary, Khairia M.; Habeeb, Moustafa M.; Al-Obidan, Areej H.

2018-05-01

New charge transfer complex (CTC) between the electron donor 2,3-diaminopyridine (DAP) with the electron acceptor chloranilic (CLA) acid has been synthesized and characterized experimentally and theoretically using a variety of physicochemical techniques. The experimental work included the use of elemental analysis, UV-vis, IR and 1H NMR studies to characterize the complex. Electronic spectra have been carried out in different hydrogen bonded solvents, methanol (MeOH), acetonitrile (AN) and 1:1 mixture from AN-MeOH. The molecular composition of the complex was identified to be 1:1 from Jobs and molar ratio methods. The stability constant was determined using minimum-maximum absorbances method where it recorded high values confirming the high stability of the formed complex. The solid complex was prepared and characterized by elemental analysis that confirmed its formation in 1:1 stoichiometric ratio. Both IR and NMR studies asserted the existence of proton and charge transfers in the formed complex. For supporting the experimental results, DFT computations were carried out using B3LYP/6-31G(d,p) method to compute the optimized structures of the reactants and complex, their geometrical parameters, reactivity parameters, molecular electrostatic potential map and frontier molecular orbitals. The analysis of DFT results strongly confirmed the high stability of the formed complex based on existing charge transfer beside proton transfer hydrogen bonding concordant with experimental results. The origin of electronic spectra was analyzed using TD-DFT method where the observed λmax are strongly consisted with the computed ones. TD-DFT showed the contributed states for various electronic transitions.

Dynamic Modelling of Tooth Deformation Using Occlusal Kinematics and Finite Element Analysis.

PubMed

Benazzi, Stefano; Nguyen, Huynh Nhu; Kullmer, Ottmar; Kupczik, Kornelius

2016-01-01

Dental biomechanics based on finite element (FE) analysis is attracting enormous interest in dentistry, biology, anthropology and palaeontology. Nonetheless, several shortcomings in FE modeling exist, mainly due to unrealistic loading conditions. In this contribution we used kinematics information recorded in a virtual environment derived from occlusal contact detection between high resolution models of an upper and lower human first molar pair (M1 and M1, respectively) to run a non-linear dynamic FE crash colliding test. MicroCT image data of a modern human skull were segmented to reconstruct digital models of the antagonistic right M1 and M1 and the dental supporting structures. We used the Occlusal Fingerprint Analyser software to reconstruct the individual occlusal pathway trajectory during the power stroke of the chewing cycle, which was applied in a FE simulation to guide the M1 3D-path for the crash colliding test. FE analysis results showed that the stress pattern changes considerably during the power stroke, demonstrating that knowledge about chewing kinematics in conjunction with a morphologically detailed FE model is crucial for understanding tooth form and function under physiological conditions. Results from such advanced dynamic approaches will be applicable to evaluate and avoid mechanical failure in prosthodontics/endodontic treatments, and to test material behavior for modern tooth restoration in dentistry. This approach will also allow us to improve our knowledge in chewing-related biomechanics for functional diagnosis and therapy, and it will help paleoanthropologists to illuminate dental adaptive processes and morphological modifications in human evolution.

Effect of unilateral extraction of molar teeth on suprahyoid muscles: macroscopic and ultrastructural aspects.

PubMed

Iyomasa, Mamie Mizusaki; Issa, João Paulo Mardegan; Siéssere, Selma; Regalo, Simone Cecílio Hallak; Watanabe, Ii-sei

2008-12-01

Anatomical and physiologic components are parts of the stomatognathic system and their interaction results in integrated functional activities. Important alterations in the masticatory system originated by dental loss affect the bone, oral mucosa and muscular function. Dental arch structures specifically designed to receive and expose teeth allow performance of their functions. But the distinction between bony and soft tissues is lost when teeth are removed since there is not a specific function to be completed. The aim of this study was to evaluate the macroscopic and ultrastructural effects of the unilateral extraction of molar teeth on the suprahyoid muscles function, using twenty young male gerbils (Meriones unguiculatus) as the experimental animal model. They were divided in experimental malocclusion (n=10) and control (n=10) groups. The experimental malocclusion group was submitted to exodontia of the left upper molars and the control group was not submitted to this procedure and served as sham-operated. For macroscopic analysis of the suprahyoid muscle, the skin was uplifted and the muscles dissected individually and removed for weight analysis according to Scherle method. The electron microscopy analysis was made in ultra thin sections of small suprahyoid muscle fragments from the experimental and control groups, examined in a Jeol 1010, 880 Kv transmission electron microscope. Several micrographs at magnifications of 3000x, 6000x, 30,000x were randomly selected for the qualitative analysis of the muscle fiber ultrastructures. Sixty days after the induced unilateral occlusal alteration no macroscopic morphologic changes was detected in the suprahyoid muscles and the muscle volume differences between the right and left sides and between groups were not significant. However, in the ultrastructural analysis suprahyoid muscles showed characteristics of specific adaptation to the unilateral occlusal alteration, by the reduced density of subsarcolemmal mitochondria and the shorter and less numerous ramifications in intermyofibrilar mitochondria localized between electronlucid myofibrils. It is concluded that unilateral exodontia of all the upper left molars affect the ultrastructural morphology of suprahyoid muscle fibers.

Superior Thermostability, Good Detonation Properties, Insensitivity, and the Effect on the Thermal Decomposition of Ammonium Perchlorate for a New Solvent-Free 3D Energetic PbII -MOF.

PubMed

Yang, Qi; Yang, Guoli; Zhang, Wendou; Zhang, Sheng; Yang, Zhaohui; Xie, Gang; Wei, Qing; Chen, Sanping; Gao, Shengli

2017-07-06

A new solvent-free energetic MOF, [Pb(HBTI)] n (1) (H 3 BTI=4,5-bis(1H-tetrazole)-1H-imidazole), has been synthesized under hydrothermal and acidic conditions. It was characterized by elemental analysis, IR, thermogravimetric, differential scanning calorimetry (DSC) and SEM. Single crystal X-ray diffraction analysis revealed that 1 features a rigid 3D framework architecture free of solvent molecules. Thermal analysis demonstrated that the thermostability of 1 was up to 325 °C. Non-isothermal kinetic and apparent thermodynamic parameters of exothermic decomposition process of 1 were determined by Kissinger's and Ozawa's methods. Through oxygen-bomb combustion calorimetry, the standard molar enthalpy of formation of 1 was determined. The calculated detonation properties (heat of detonation, detonation velocity and detonation pressure) and sensitivity tests of 1 were carried out. In addition, 1 was explored as combustion promoter to accelerate the thermal decompositions of ammonium perchlorate (AP) by differential scanning calorimetry. Experimental results indicated that 1 possesses potential application prospects in the field of explosives and propellants. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficiency of molar distalization associated with second and third molar eruption stage.

PubMed

Flores-Mir, Carlos; McGrath, Lisa; Heo, Giseon; Major, Paul W

2013-07-01

To evaluate the efficiency of molar distalization associated with the second and third molar eruption stage. A systematic computerized database search was conducted using several databases. Adaptations of the terms molar distalization and distalizing appliances were used. The reference lists of all the selected articles were also searched for any potential articles that might have been missed in the electronic search. The data provided in the selected publications were grouped and analyzed in terms of molar distalization with respect to various eruption stages of maxillary second and third molars. Out of the 13 initially identified articles only four fulfilled the final selection criteria. Three of the four studies showed no statistical significance in linear molar distalization based on the eruptive stage of the second and/or third molars, while one study found that the amount of distal movement of the first molars was significantly greater in the group with unerupted second molars. Only one study found that the amount of molar tipping that occurred as a result of distalization was related to the eruption stage of the maxillary molars. Similarly, three of the four studies found that molar distalization time was not significantly affected by eruption of the second or third molars. The effect of maxillary second and third molar eruption stage on molar distalization-both linear and angular distalization-appears to be minimal. This conclusion is only based on low-level of evidence clinical trials. The large variability in the outcomes should be considered clinically.

Dietary Ecology of Murinae (Muridae, Rodentia): A Geometric Morphometric Approach

PubMed Central

Gómez Cano, Ana Rosa; Hernández Fernández, Manuel; Álvarez-Sierra, M. Ángeles

2013-01-01

Murine rodents represent a highly diverse group, which displays great ecological versatility. In the present paper we analyse the relationship between dental morphology, on one hand, using geometric morphometrics based upon the outline of first upper molar and the dietary preference of extant murine genera, on the other. This ecomorphological study of extant murine rodents demonstrates that dietary groups can be distinguished with the use of a quantitative geometric morphometric approach based on first upper molar outline. A discriminant analysis of the geometric morphometric variables of the first upper molars enables us to infer the dietary preferences of extinct murine genera from the Iberian Peninsula. Most of the extinct genera were omnivore; only Stephanomys showed a pattern of dental morphology alike that of the herbivore genera. PMID:24236090

Endodontic Management of Maxillary First Molar With Two Palatal Canals Aided With Cone Beam Computed Tomography: A Case Report.

PubMed

Pamboo, Jaya; Hans, Manoj Kumar; Chander, Subhas; Sharma, Kapil

2017-04-01

The success of endodontic therapy is based on having sufficient endodontic access, correct cleaning and shaping, and adequate root canal obturation. However, endodontic treatment is also dependent on having a sound knowledge of the internal anatomy of human teeth, especially when anatomic variations are present. Reporting these alterations is important for improving the understanding and expertise of endodontists. The aim of this case report is to describe a unique case of maxillary first molar with 2 palatal canals within a single root, as confirmed by cone-beam computed tomography (CBCT) scans. This article also reviews recent case reports of extra palatal root canals in the maxillary first molars and the role of CBCT analysis in successfully diagnosing them.

Impact of Bisphosphonate on Orthodontic tooth movement and osteoclastic count: An Animal Study.

PubMed

Venkataramana, V; Chidambaram, S; Reddy, B Vishnuvardhan; Goud, E V Soma Shekara; Arafath, Mohammed; Krishnan6, Santhana

2014-04-01

Background : The aim of the current study is to examine the effect of systemically administered BP-Pamidronate, on Orthodontic Tooth Movement (OTM) along with osteoclastic quantification in New Zealand white rabbits. Materials & Methods : Twenty rabbits used in the study, were equally divided into 2 groups ; Group-1 as Control & Group-2 as Experimental. A sentalloy NITI closed coil spring (GAC International, USA) of 100 gram force, ligated between the lower first molar and the anterior most incisors of the rabbit has served as orthodontic force element. The BP- Pamidronate was administered at the dosage of 1.5 mg/kg body intra-peritonially, on the 1st, 7th and 14th day of the experiment. On the 21st day both group of animals were sacrificed, mandibles were dissected. The formed diastema between the 1st and 2nd molar was measured on the dissected mandibles using standard metric scale, which is considered as the OTM in the mesial direction. Next, the alveolar bone regions along with intact mesial surfaces were processed for histological investigation (osteoclastic count). Results : The student 't' test has been done to compare the mean values of molar tooth movement and osteoclastic count. Parameter :1 molar tooth movement has shown a significant difference between the control (3.750 ± 0.548 mm) and the experimental group (3.050 ± 0.556 mm) with calculated 'p' value (p-value <0.05) is significant at 0.0110 level. Parameter : 2 osteoclastic count has shown a significant difference between the control (13.335000 ± 0.735856 per square mm.) and the experimental group (11.426900 ± 1.49369 per square mm) calculated 'p' value (p-value <0.05) is significant at 0.003 level. Conclusion : The molar tooth movement and the osteoclastic count were significantly reduced in BP - Pamidronate administered animals than non-drug recipients. How to cite the article: Venkataramana V, Chidambaram S, Reddy BV, Goud EV, Arafath M, Krishnan S. Impact of Bisphosphonate on Orthodontic tooth movement and olsteoclastic count: An Animal Study. J Int Oral Health 2014;6(2):1-8.

Impact of Bisphosphonate on Orthodontic tooth movement and osteoclastic count: An Animal Study

PubMed Central

Venkataramana, V; Chidambaram, S; Reddy, B Vishnuvardhan; Goud, E V Soma Shekara; Arafath, Mohammed; Krishnan, Santhana

2014-01-01

Background : The aim of the current study is to examine the effect of systemically administered BP-Pamidronate, on Orthodontic Tooth Movement (OTM) along with osteoclastic quantification in New Zealand white rabbits. Materials & Methods : Twenty rabbits used in the study, were equally divided into 2 groups ; Group-1 as Control & Group-2 as Experimental. A sentalloy NITI closed coil spring (GAC International, USA) of 100 gram force, ligated between the lower first molar and the anterior most incisors of the rabbit has served as orthodontic force element. The BP- Pamidronate was administered at the dosage of 1.5 mg/kg body intra-peritonially, on the 1st, 7th and 14th day of the experiment. On the 21st day both group of animals were sacrificed, mandibles were dissected. The formed diastema between the 1st and 2nd molar was measured on the dissected mandibles using standard metric scale, which is considered as the OTM in the mesial direction. Next, the alveolar bone regions along with intact mesial surfaces were processed for histological investigation (osteoclastic count). Results : The student ‘t’ test has been done to compare the mean values of molar tooth movement and osteoclastic count. Parameter :1 molar tooth movement has shown a significant difference between the control (3.750 ± 0.548 mm) and the experimental group (3.050 ± 0.556 mm) with calculated ‘p’ value (p-value <0.05) is significant at 0.0110 level. Parameter : 2 osteoclastic count has shown a significant difference between the control (13.335000 ± 0.735856 per square mm.) and the experimental group (11.426900 ± 1.49369 per square mm) calculated ‘p’ value (p-value <0.05) is significant at 0.003 level. Conclusion : The molar tooth movement and the osteoclastic count were significantly reduced in BP – Pamidronate administered animals than non-drug recipients. How to cite the article: Venkataramana V, Chidambaram S, Reddy BV, Goud EV, Arafath M, Krishnan S. Impact of Bisphosphonate on Orthodontic tooth movement and olsteoclastic count: An Animal Study. J Int Oral Health 2014;6(2):1-8. PMID:24876695

40 CFR Table A-7 to Subpart A of... - Data Elements That Are Inputs to Emission Equations and for Which the Reporting Deadline Is March...

Code of Federal Regulations, 2014 CFR

2014-07-01

....116(b) Only annual production by product from each EAF (No CEMS). K 98.116(e)(4) All. K 98.116(e)(5... factor if using Eq. Y-3. Y 98.256(e)(10) Only fraction of carbon in the flare gas contributed by methane... methane in coking gas. Y 98.256(l)(5) Only molar volume conversion factor. Y 98.256(m)(3) Only total...

Magnetic Properties of the DNA-Quaternary Ammonium Surfactant Complexes Studied by EMR Spectroscopy and SQUID Measurement

DTIC Science & Technology

2008-09-24

Eui Doo Do, Dong Hoon Choi, and Jung -Il Jin∗ Department of Chemistry, Korea University, Seoul 136-701, Korea Chang Hoon Lee Department of Polymer...Electromagnetic Properties of Modified DNA 5a. CONTRACT NUMBER FA48690714023 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Jung -Il Jin 5d...the last temperature- independent χPauli is the Pauli spin susceptibility attributed by delocalized con- ductive spin species. The molar

Cone-beam Computed Tomographic Study of Root Anatomy and Canal Configuration of Molars in a Spanish Population.

PubMed

Pérez-Heredia, Mercedes; Ferrer-Luque, Carmen María; Bravo, Manuel; Castelo-Baz, Pablo; Ruíz-Piñón, Manuel; Baca, Pilar

2017-09-01

The aim of this study was to identify morphologic peculiarities of roots and analyze the root canal configuration in maxillary and mandibular first and second molars by means using cone-beam computed tomographic (CBCT) imaging in a Spanish population. A total of 284 maxillary molars and 242 mandibular molars from 112 patients were examined in vivo by CBCT imaging; only untreated molars with healthy and fully matured apices were included in this study. Details regarding the number of roots, number of canals, and root canal configuration were recorded. Maxillary first and second molars had 3 roots in 97.2% and 79%, respectively. In mandibular molars, the frequency of 2 roots was 94% in first molars and 83% in second molars. The canal configuration of the palatal root was 100% Vertucci type I (1-1) in first and second molars. The distobuccal root showed a Vertucci type I configuration in 97% of first and 100% of maxillary second molars. The mesiobuccal root for first molars showed a Vertucci type II configuration (2-1) in 56.5% cases and Vertucci type IV (2-2) in 23.2%. For maxillary second molars, the Vertucci type I configuration reached 52.7%. In mandibular molars, the mesial root showed higher variability. Most frequent was the presence of 2 canals, Vertucci type II for first and second molars. In the distal root, the most common configuration was Vertucci type I in both molars. The greater percentage of fused roots was observed in maxillary molars. Vertucci type II configuration was more frequent than type IV in the mesial root of mandibular molars and the mesiobuccal root of maxillary molars. A third canal in the mesial root of first mandibular molars (6.7%) was higher than expected. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Morphologic analysis of third-molar maturity by digital orthopantomographic assessment.

PubMed

Introna, Francesco; Santoro, Valeria; De Donno, Antonio; Belviso, Maura

2008-03-01

Accurate timing of the eruption of first and permanent teeth is an important parameter in forensic odontology to establish the age of dead or live individuals. Determination of adulthood may determine, for example, whether an individual convicted of a crime is sentenced as an adult and incarcerated in a state penal institution or as a juvenile and sent to a juvenile camp. At present, there is a large immigrant population in Italy, and young foreign criminals sometimes have false passports bearing a later birth date, with the aim of evading punishment. In such circumstances, age determination is becoming a significant forensic issue.Late in adolescence, after formation of the premolars and canines, only the third molars continue to develop. According to several studies, although the third molars are the most variable teeth in the dentition, they remain the most reliable biologic indicator available for estimation of age during the middle teens and early twenties.In this study, the authors test the possibilities offered by orthopantomography executed by means of digital technology, with the aim of exploiting the advantages of the computerized digital technique compared with the conventional technique, to determine adult age on the basis of root development of the third molar.Digital radiography is simple to use, quick, and effective, allowing superimposition and enlargement; the images can be electronically stored and transported. In comparison with traditional orthopantomography, the digital technique features greater diagnostic accuracy of some anatomic structures: upper and lower front teeth, root apexes, floor of the nasal fossa and maxillary sinus, nasal septum, mandibular condylus. Moreover, digital orthopantomography suffers less from artifacts.The digital orthopantomographies of 83 Caucasian subjects (43 females and 40 males) aged between 16 and 22 years were analyzed in standard conditions, assessing the degree of maturation of the upper and lower third molars. A standardized computer procedure was used to acquire the x-ray images, recording 3 per plate: the overall orthopantomography and 2 enlargements of optical type of the left and right sides, to reveal the third molars while maintaining unaltered the image resolution.For the analysis, the authors adopted Demirjian's staging system that classifies development of the third molar in 8 stages (A, B, C, D, E, F, G, H) on the basis of morphologic criteria. This has been statistically proved to feature notable precision and high predictive ability.To assess any sex-related variations in mineralization speed, the series was subdivided by gender. The study demonstrated that such differences are more evident under the age of 18 years.Overall, the observation of 245 third molars showed faster development of the upper than the lower third molars, a prevalence of stages D to G in the age range between 16 and 18 years, and a clear predominance of stage H in individuals over 18 years of age. Finally, an intermediate stage between G and H was demonstrated in subjects aged between 17 and 21 years.

Three-dimensional finite element analysis of the craniomaxillary complex during maxillary protraction with bone anchorage vs conventional dental anchorage.

PubMed

Yan, Xiulin; He, Weijun; Lin, Tao; Liu, Jun; Bai, Xiaofeng; Yan, Guangqi; Lu, Li

2013-02-01

The aim of this study was to explore the biomechanical effects on the craniomaxillary complex of bone anchorage and dental anchorage during maxillary protraction. We established 2 finite element models. One simulated maxillary protraction with dental anchorage in the maxillary first molars and the other with bone anchorage in the infrazygomatic buttresses of the maxilla. The magnitude of the applied forces was 500 g per side, and the force directions were 0°, 10°, 20°, and 30° forward and downward relative to the occlusal plane. The finite element model of the craniomaxillary complex could displace in an almost translatory manner when the force direction was about 20° in the bone anchorage model and about 30° in the dental anchorage model. The nodes representing the sutures at the back of the maxilla showed greater stress in the bone anchorage model than in the dental anchorage model in the same force direction. It is the opposite at the front of the maxilla. We should determine the direction of applied force according to the anchorage location and skeletal characteristics of patients before maxillary protraction. The dramatic effects of maxillary protraction with bone anchorage can be based on the advantages of bone anchorage, not on the changes in the region of the applied force. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

The association between enamel fluorosis and dental caries in U.S. schoolchildren.

PubMed

Iida, Hiroko; Kumar, Jayanth V

2009-07-01

The authors assessed the association between enamel fluorosis and dental caries to determine if there is any beneficial effect of enamel fluorosis in U.S. schoolchildren. The authors used data from a National Institute of Dental Research survey of the oral health of U.S. children conducted in 1986 and 1987 to determine the prevalence of caries and mean decayed, missing or filled surfaces on permanent maxillary right first molars in children 7 to 17 years of age who had a history of a single residence. (To date, this is the only national oral health data set in the United States with detailed information on fluoride exposures.) They examined the association between enamel fluorosis and caries using logistic regression analysis, controlling for potential confounders in communities with water at or above optimal fluoridation levels and in communities with nonfluoridated or suboptimally fluoridated water. Permanent maxillary right first molars with fluorosis consistently had lower levels of caries experience than did normal molars. Adjusted odds ratios for caries prevalence in molars with fluorosis were 0.71 (95 percent confidence interval [CI], 0.56-0.89) in communities with nonfluoridated or suboptimally fluoridated water and 0.89 (95 percent CI, 0.74-1.06) in communities with water at or above optimal fluoridation levels. This study's findings suggest that molars with fluorosis are more resistant to caries than are molars without fluorosis. The results highlight the need for those considering policies regarding reduction in fluoride exposure to take into consideration the caries-preventive benefits associated with milder forms of enamel fluorosis.

Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes

NASA Astrophysics Data System (ADS)

Alnoor, Hatim; Pozina, Galia; Khranovskyy, Volodymyr; Liu, Xianjie; Iandolo, Donata; Willander, Magnus; Nur, Omer

2016-04-01

Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5 M exhibit stronger yellow emission (˜575 nm) compared to those based on 1:1 and 1:3 M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination.

Anatomical analysis of the resected roots of mandibular first molars after failed non-surgical retreatment

PubMed Central

2018-01-01

Objectives Understanding the reason for an unsuccessful non-surgical endodontic treatment outcome, as well as the complex anatomy of the root canal system, is very important. This study examined the cross-sectional root canal structure of mandibular first molars confirmed to have failed non-surgical root canal treatment using digital images obtained during intentional replantation surgery, as well as the causative factors of the failed conventional endodontic treatments. Materials and Methods This study evaluated 115 mandibular first molars. Digital photographic images of the resected surface were taken at the apical 3 mm level and examined. The discolored dentin area around the root canal was investigated by measuring the total surface area, the treated areas as determined by the endodontic filling material, and the discolored dentin area. Results Forty 2-rooted teeth showed discolored root dentin in both the mesial and distal roots. Compared to the original filled area, significant expansion of root dentin discoloration was observed. Moreover, the mesial roots were significantly more discolored than the distal roots. Of the 115 molars, 92 had 2 roots. Among the mesial roots of the 2-rooted teeth, 95.7% of the roots had 2 canals and 79.4% had partial/complete isthmuses and/or accessory canals. Conclusions Dentin discoloration that was not visible on periapical radiographs and cone-beam computed tomography was frequently found in mandibular first molars that failed endodontic treatment. The complex anatomy of the mesial roots of the mandibular first molars is another reason for the failure of conventional endodontic treatment. PMID:29765897

Tributyltin impairs dentin mineralization and enamel formation in cultured mouse embryonic molar teeth.

PubMed

Salmela, Eija; Sahlberg, Carin; Alaluusua, Satu; Lukinmaa, Pirjo-Liisa

2008-11-01

Tributyltin (TBT), earlier used as an antifouling agent in marine paints, causes damage to the aquatic ecosystem, for example, impaired shell calcification in oysters. TBT affects hard tissue mineralization even in mammals: delayed bone mineralization has been observed in rodents exposed to TBT in utero. To see if TBT interferes with tooth development, especially dental hard tissue formation, we exposed mouse E18 mandibular first and second molars to 0.1, 0.5, 1.0, and 2.0 microM TBT chloride in organ culture for 7-12 days. The amount of enamel was assessed and the sizes of the first molars were measured from photographs taken after the culture. TBT concentration dependently impaired enamel formation (p < 0.001) and reduced tooth size (p < 0.001). Histological analysis showed slight arrest of dentin mineralization and enamel formation in first molars exposed to 0.1 microM TBT. At the concentration of 1.0 microM the effect was overt. The differentiation of ameloblasts in the mesial cusps was retarded but TBT had no effect on odontoblast morphology. The dental epithelium showed enhanced apoptosis. The failure of ameloblasts to form enamel was likely to be secondary to the effect of TBT on dentin mineralization. In the second molars, where predentin deposition had not started, ameloblasts and odontoblasts were nonpolarized and proliferative. The results showed that TBT concentration dependently impairs dental hard tissue formation and reduces tooth size in cultured mouse embryonic molars. The effects depend on the stage of tooth development at the start of exposure and may involve epithelial-mesenchymal interactions.

Molar Macrowear Reveals Neanderthal Eco-Geographic Dietary Variation

PubMed Central

Fiorenza, Luca; Benazzi, Stefano; Tausch, Jeremy; Kullmer, Ottmar; Bromage, Timothy G.; Schrenk, Friedemann

2011-01-01

Neanderthal diets are reported to be based mainly on the consumption of large and medium sized herbivores, while the exploitation of other food types including plants has also been demonstrated. Though some studies conclude that early Homo sapiens were active hunters, the analyses of faunal assemblages, stone tool technologies and stable isotopic studies indicate that they exploited broader dietary resources than Neanderthals. Whereas previous studies assume taxon-specific dietary specializations, we suggest here that the diet of both Neanderthals and early Homo sapiens is determined by ecological conditions. We analyzed molar wear patterns using occlusal fingerprint analysis derived from optical 3D topometry. Molar macrowear accumulates during the lifespan of an individual and thus reflects diet over long periods. Neanderthal and early Homo sapiens maxillary molar macrowear indicates strong eco-geographic dietary variation independent of taxonomic affinities. Based on comparisons with modern hunter-gatherer populations with known diets, Neanderthals as well as early Homo sapiens show high dietary variability in Mediterranean evergreen habitats but a more restricted diet in upper latitude steppe/coniferous forest environments, suggesting a significant consumption of high protein meat resources. PMID:21445243

"Zip me up, and cool me down": Molar narratives and molecular intensities in 'helicopter' mental health services.

PubMed

McGrath, Laura; Reavey, Paula

2016-03-01

Experiences of the space-time dimensions of contemporary mental health services are shaped according to what we describe here as a 'helicopter service', where professionals drop down into service users' lives for short, often pre-determined bursts of time. This can create a system where users' experiences are observed and assessed from a more distanced and circumscribed perspective. This paper considers the implications of these systemic changes, using interviews with current UK service users. To help in the exploration of the complexities faced by service users', we use Deleuze and Guatarri's (1987) distinction between molar and molecular forms of organisation. A process oriented thematic analysis discusses: a) Affording narratives of distress: Molarity, monitoring and space in service interactions and b) Narratives in therapy: Compartmentalising the distressed self. Multiple aspects of the relationship between space and distress are explored. An understanding of experiences of distress beyond the boundaries of the molar, which considers its intensive, molecular and transformative nature, may help to open up engagement with the affective and emotional dimensions of mental health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study on Pleistocene Fossil Cats (Carnivora, Felidae) From a Limestone Cave in Kenting, Southern Taiwan, East Asia

NASA Astrophysics Data System (ADS)

Gan, Yi; Chang, Chun-Hsiang; Wu, Ming-Chee

2016-04-01

The limestone cave, Lobster Cave, located in the Kenting National Park of southern Taiwan, is yielding numerous Pleistocene mammalian fossils buried within the continental deposits. In this study, fossil molars of clouded leopard (Neofelis nebulosa) recovered from the same horizon in the cave, were examined. Three isolated felid molars; p3, p4 and m1, having a series of progressive increase in size, were believed as belonged to the same individual. Traditional linear measurement and two-dimensional geometric morphometric analysis for the occlusal surface outlines have been conducted on the fossil molars; comparisons were also done with the extant clouded leopard. Results obtained have shown that the cave fossil clouded leopard is closer to the extant clouded leopard in molar characters; but, are slightly larger than the extant ones in their size. Nevertheless, even the clouded leopard in Taiwan was regarded as to have been extinct and its past existence has still been in doubt, the current study revealed that the clouded leopards have inhabited in Taiwan since Pleistocene, and has a larger body size than that of the recent one.

Comparison of mesiodistal tooth widths in Caucasian, African and Japanese individuals with Brazilian ancestry and normal occlusion.

PubMed

Fernandes, Thais Maria Freire; Sathler, Renata; Natalício, Gabriela Letícia; Henriques, José Fernando Castanha; Pinzan, Arnaldo

2013-01-01

To observe the presence of sexual dimorphism and compare the mesiodistal width of the teeth in Caucasian, African and Japanese individuals with Brazilian ancestry not orthodontically treated and with normal occlusion. One hundred pairs of dental casts were used. It was measured, from first molar to first molar in both arches, the teeth's mesiodistal widths, using a digital caliper. For the statistical analysis of results Kolmogorov-Smirnov, t test, ANOVA and Tukey's test (p < 0.05) were used. Sexual dimorphism occurred on the three evaluated groups, and the highest mesiodistal widths were found in males. There was statistically significant difference between racial groups in all evaluated teeth in males. However, in females, this same difference was found only on upper lateral incisor and first molar; and lower lateral incisor, canine, first premolar and first molar. Most of mesiodistal measures present particular characteristics in relation to gender, with higher values for males, and to race, with a tendency for African to present greater mesiodistal distance of the teeth, followed by Japanese and Caucasians, respectively, important for the correct diagnosis and orthodontic planning.

Comparing the Efficiencies of Third Molar Surgeries With and Without a Dentist Anesthesiologist.

PubMed

Reebye, Uday; Young, S; Boukas, E; Davidian, E; Carnahan, J

2017-01-01

Two different anesthesia models were compared in terms of surgical duration, safer outcomes, and economic implications. Third molar surgeries performed with and without a separate dentist anesthesiologist were evaluated by a retrospective data analysis of the surgical operative times. For more difficult surgeries, substantially shorter operative times were observed with the dentist anesthesiologist model, leading to a more favorable surgical outcome. An example calculation is presented to demonstrate economic advantages of scheduling the participation of a dentist anesthesiologist for more difficult surgeries.

Predictive model of third molar eruption after second molar extraction.

PubMed

De-la-Rosa-Gay, Cristina; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2010-03-01

Extraction of second permanent molars is an option for providing space in orthodontic treatment. Although many articles have described its impact on the outcome, there are few data on the prognosis of the eruption of the adjacent third molars. The aims of this investigation were to provide predictive models of eruption of third molars after second permanent molar extraction and to validate them. A total of 48 patients (ages, 11-23 years) who had 128 second permanent molars (54 maxillary, 74 mandibular) extracted during orthodontic treatment were followed until eruption of the third molars was complete. A lineal regression model predicted the final angle of the third molars with the permanent first molar by using the variables of initial angle, jaw, and the developmental stage of the third molar. A logistic regression model predicted the probability of correct eruption by using the variables of initial angle, jaw, sex, age, and the developmental stage of the third molar. 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Correction of a mutilated dentition with mini-implants as anchorage.

PubMed

Hyun, Jae-Man; Kim, Tae-Woo

2010-11-01

The patient was an adolescent boy, aged 15.6 years, with a mutilated dentition. He had extrusion of the maxillary left first molar because of loss of the mandibular first molar and lingual tilting and rotation of the mandibular second molars. Both left and right second molars were in scissors-bite that was more severe on the left side. By using mini-implants and a TPA with hooks, a 3-mm intrusion was successfully made on the maxillary left first molar. This provided room for mesial movement of the mandibular left second molar. The second molar was protracted into the space of the missing first molar, and the mandibular left third molar was positioned in place of the second molar. The second molars scissors-bite was corrected. Active treatment took 45 months, and the treatment result remained stable 2 years after debonding. Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Synthesis, characterization, antimicrobial activity and carbonic anhydrase enzyme inhibitor effects of salicilaldehyde-N-methyl p-toluenesulfonylhydrazone and its Palladium(II), Cobalt(II) complexes

NASA Astrophysics Data System (ADS)

Alyar, Saliha; Adem, Şevki

2014-10-01

We report the synthesis of the ligand, salicilaldehyde-N-methyl p-toluenesulfonylhydrazone (salptsmh) derived from p-toluenesulfonicacid-1-methylhydrazide (ptsmh) and its Pd(II) and Co(II) metal complexes were synthesized for the first time. The structure of the ligand and their complexes were investigated using elemental analysis, magnetic susceptibility, molar conductance and spectral (IR, NMR and LC-MS) measurements. Salptsmh has also been characterized by single crystal X-ray diffraction. 1H and 13C shielding tensors for crystal structure were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The complexes were found to have general composition [ML2]. The results of elemental analysis showed 1:2 (metal/ligand) stoichiometry for all the complex. Magnetic and spectral data indicate a square planar geometry for Pd(II) complex and a distorted tetrahedral geometry for Co(II) complexes. The ligand and its metal chelates have been screened for their antimicrobial activities using the disk diffusion method against the selected Gram positive bacteria: Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Gram negative bacteria: Eschericha coli, Pseudomonas aeruginosa, Klebsiella pneumonia. The inhibition activities of these compounds on carbonic anhydrase II (CA II) and carbonic anhydrase I (CA I) have been investigated by comparing IC50 and Ki values and it has been found that Pd(II) complex have more enzyme inhibition efficiency than salptsmh and Co(II) complex.

A Three-Dimensional Finite Element Analysis of the Stress Distribution Generated by Splinted and Nonsplinted Prostheses in the Rehabilitation of Various Bony Ridges with Regular or Short Morse Taper Implants.

PubMed

Toniollo, Marcelo Bighetti; Macedo, Ana Paula; Rodrigues, Renata Cristina; Ribeiro, Ricardo Faria; de Mattos, Maria G

The aim of this study was to compare the biomechanical performance of splinted or nonsplinted prostheses over short- or regular-length Morse taper implants (5 mm and 11 mm, respectively) in the posterior area of the mandible using finite element analysis. Three-dimensional geometric models of regular implants (Ø 4 × 11 mm) and short implants (Ø 4 × 5 mm) were placed into a simulated model of the left posterior mandible that included the first premolar tooth; all teeth posterior to this tooth had been removed. The four experimental groups were as follows: regular group SP (three regular implants were rehabilitated with splinted prostheses), regular group NSP (three regular implants were rehabilitated with nonsplinted prostheses), short group SP (three short implants were rehabilitated with splinted prostheses), and short group NSP (three short implants were rehabilitated with nonsplinted prostheses). Oblique forces were simulated in molars (365 N) and premolars (200 N). Qualitative and quantitative analyses of the minimum principal stress in bone were performed using ANSYS Workbench software, version 10.0. The use of splinting in the short group reduced the stress to the bone surrounding the implants and tooth. The use of NSP or SP in the regular group resulted in similar stresses. The best indication when there are short implants is to use SP. Use of NSP is feasible only when regular implants are present.

Modeling dental composite shrinkage by digital image correlation and finite element methods

NASA Astrophysics Data System (ADS)

Chen, Terry Yuan-Fang; Huang, Pin-Sheng; Chuang, Shu-Fen

2014-10-01

Dental composites are light-curable resin-based materials with an inherent defect of polymerization shrinkage which may cause tooth deflection and debonding of restorations. This study aimed to combine digital image correlation (DIC) and finite element analysis (FEA) to model the shrinkage behaviors under different light curing regimens. Extracted human molars were prepared with proximal cavities for composite restorations, and then divided into three groups to receive different light curing protocols: regular intensity, low intensity, and step-curing consisting of low and high intensities. For each tooth, the composite fillings were consecutively placed under both unbonded and bonded conditions. At first, the shrinkage of the unbonded restorations was analyzed by DIC and adopted as the setting of FEA. The simulated shrinkage behaviors obtained from FEA were further validated by the measurements in the bonded cases. The results showed that different light curing regimens affected the shrinkage in unbonded restorations, with regular intensity showing the greatest shrinkage strain on the top surface. The shrinkage centers in the bonded cases were located closer to the cavity floor than those in the unbonded cases, and were less affected by curing regimens. The FEA results showed that the stress was modulated by the accumulated light energy density, while step-curing may alleviate the tensile stress along the cavity walls. In this study, DIC provides a complete description of the polymerization shrinkage behaviors of dental composites, which may facilitate the stress analysis in the numerical investigation.

Three-Dimensional Finite Element Analysis on Stress Distribution of Internal Implant-Abutment Engagement Features.

PubMed

Cho, Sung-Yong; Huh, Yun-Hyuk; Park, Chan-Jin; Cho, Lee-Ra

To investigate the stress distribution in an implant-abutment complex with a preloaded abutment screw by comparing implant-abutment engagement features using three-dimensional finite element analysis (FEA). For FEA modeling, two implants-one with a single (S) engagement system and the other with a double (D) engagement system-were placed in the human mandibular molar region. Two types of abutments (hexagonal, conical) were connected to the implants. Different implant models (a single implant, two parallel implants, and mesial and tilted distal implants with 1-mm bone loss) were assumed. A static axial force and a 45-degree oblique force of 200 N were applied as the sum of vectors to the top of the prosthetic occlusal surface with a preload of 30 Ncm in the abutment screw. The von Mises stresses at the implant-abutment and abutment-screw interfaces were measured. In the single implant model, the S-conical abutment type exhibited broader stress distribution than the S-hexagonal abutment. In the double engagement system, the stress concentration was high in the lower contact area of the implant-abutment engagement. In the tilted implant model, the stress concentration point was different from that in the parallel implant model because of the difference in the bone level. The double engagement system demonstrated a high stress concentration at the lower contact area of the implant-abutment interface. To decrease the stress concentration, the type of engagement features of the implant-abutment connection should be carefully considered.

Assessment of White Spot Lesions and In-Vivo Evaluation of the Effect of CPP-ACP on White Spot Lesions in Permanent Molars of Children.

PubMed

Munjal, Deepti; Garg, Shalini; Dhindsa, Abhishek; Sidhu, Gagandeep Kaur; Sethi, Harsimran Singh

2016-05-01

As hindrance of remineralisation process occurs during orthodontic therapy resulting in decalcification of enamel because number of plaque retention sites increases due to banding and bonding of appliances to teeth. The present analytic study was undertaken to assess the occurrence of white spot lesions in permanent molars of children with and without orthodontic therapy and to evaluate the effect of Casein PhosphoPeptide-Amorphous Calcium Phosphate (CPP-ACP) on white spot lesions in post-orthodontic patients in a given period of time. The study comprised of examination of 679 first permanent molars which were examined to assess the occurrence of smooth surface white spot lesions in children of 8 to 16 years age group. Group I comprised subjects without any orthodontic treatment and Group II comprised of subjects who had undergone orthodontic therapy. The sample size was calculated using the epi-info6 computer package. Treatment group included 20 post-orthodontic patients examined with at least one white spot lesion within the enamel who received remineralizing cream (GC Tooth Mousse, Recaldent, GC Corporation.) i.e., CPP-ACP cream two times a day for 12 consecutive weeks. Computerized image analysis method was taken to evaluate white spot lesions. These frequency and percentages were compared with chi-square test. For comparison of numeric data, paired t-test was used. Of the total 278 (49.6%) first permanent molars showed occurrence of smooth surface white spot lesions out of 560 in Group I and 107 (89.9%) first permanent molars showed presence of white spot lesions out of 119 debanded first permanent molars of children examined in Group II. CPP-ACP therapy group showed reduction in severity of codes which was found to be highly significant after 12 weeks and eight weeks on gingival-third, p-value (<0.001) and significant after eight weeks and four weeks on middle-third according to ICDAS II criteria and computerized image analysis. CPP-ACP therapy minimum for 12 weeks is highly recommended as post-orthodontic treatment need in management of smooth surface white spot lesions on teeth undergoing fixed orthodontic therapy according to the present study.

Tooth coronal index and pulp/tooth ratio in dental age estimation on digital panoramic radiographs-A comparative study.

PubMed

Jain, Supreet; Nagi, Ravleen; Daga, Minal; Shandilya, Ashutosh; Shukla, Aastha; Parakh, Abhinav; Laheji, Afshan; Singh, Rahul

2017-08-01

Assessment of an age of an individual whether living or dead through teeth is one of the most reliable and simple method to calculate age than skeletal remains especially when they are in poor conditions. The study was carried out with aim of (i) to evaluate reliability of dental age assessment through two different methods for adults i.e. tooth coronal index and pulp/tooth ratio using digital panoramic radiographs and (ii) to compare these methods for their accuracy in age determination. The digital panoramic radiographs of 180 subjects of Chhattisgarh aged 15-70 years were selected for the study. The measurements were performed on the JPEG images of selected panoramic radiographs by using Adobe Acrobat 7.0 professional software. For tooth coronal index (TCI), height of the crown i.e. coronal height (CH) and the height of the coronal pulp cavity i.e. coronal pulp cavity height (CPCH) of mandibular second premolars and first molars was measured in millimeter (mm) and then TCI was calculated for each tooth and calculated age was compared with chronological age. For pulp/tooth ratio, the measurements of pulp chamber height (PCH) and crown root trunk height (CRTH) were performed on the mandibular first and second molar teeth, the pulp chamber crown root trunk height ratios (PCTHR) of selected tooth were calculated. The acquired data were subjected to Pearson correlation test, unpaired t test and Analysis of Variance (ANOVA) analysis. Results suggested that TCI (mandibular first molar r=-0.178), second premolar (r=-0.187) and PCTHR(mandibular first molar r=-0.921, second molar r=-0.901) correlated negatively with chronological age suggesting decrease in size of pulp cavity. Mandibular first molar was found to be most reliable tooth to estimate dental age. The study showed that both PCTHR and TCI have negative association with chronological age. PCTHR showed slightly higher negative correlation and proved as a better tool for age estimation than TCI. Statistically significant differences were observed between chronological and calculated age by both methods thus emphasizing the need for future clinical trials. Copyright © 2017 Elsevier B.V. All rights reserved.

Dentomaxillofacial characteristics of ectodermal dysplasia.

PubMed

Nakayama, Yumiko; Baba, Yoshiyuki; Tsuji, Michiko; Fukuoka, Hiroki; Ogawa, Takuya; Ohkuma, Mizue; Moriyama, Keiji

2015-02-01

The aim of this retrospective hospital-based study was to elucidate the dentomaxillofacial characteristics of ectodermal dysplasia. Six Japanese individuals (one male and five female; age range, 12.7-27.2 years) underwent comprehensive examinations, including history recording, cephalometric analysis, panoramic radiography, and analysis of dental models. All the subjects had two or more major manifestations for clinical diagnosis of ectodermal dysplasia (e.g., defects of hair, teeth, nails, and sweat glands). They presented hypodontia (mean number of missing teeth, 9.5; range, 5-14), especially in the premolar region, and enamel dysplasia. Five subjects had bilateral molar occlusion, whereas one subject had unilateral molar occlusion. The common skeletal features were small facial height, maxillary hypoplasia, counterclockwise rotation of the mandible, and mandibular protrusion. Interestingly, the maxillary first molars were located in higher positions and the upper anterior facial height was smaller than the Japanese norm. The results suggest that vertical and anteroposterior maxillary growth retardation, rather than lack of occlusal support due to hypodontia, leads to reduced anterior facial height in individuals with ectodermal dysplasia. © 2014 Japanese Teratology Society.

Do systemic antibiotics prevent dry socket and infection after third molar extraction? A systematic review and meta-analysis.

PubMed

Ramos, Eva; Santamaría, Joseba; Santamaría, Gorka; Barbier, Luis; Arteagoitia, Icíar

2016-10-01

The use of antibiotics to prevent dry socket and infection is a controversial but widespread practice. The aim of the study is to assess the efficacy of systemic antibiotics in reducing the frequencies of these complications after extraction. A systematic review and meta-analysis, according to the PRISMA statement, based on randomized double-blind placebo-controlled trials evaluating systemic antibiotics to prevent dry socket and infection after third molar surgery. Databases were searched up to June 2015. Relative risks (RRs) were calculated with inverse variance-weighted, fixed-effect, or random-effect models. We included 22 papers in the qualitative and 21 in the quantitative review (3304 extractions). Overall-RR was 0.43 (95% confidence interval [CI] 0.33-0.56; P < .0001); number needed to treat, 14 (95% CI 11-19). Penicillins-RR: 0.40 (95% CI 0.27-0.59). Nitroimidazoles-RR: 0.56 (95% CI 0.38-0.82). No serious adverse events were reported. Systemic antibiotics significantly reduce the risk of dry socket and infection in third molar extraction. Copyright © 2016 Elsevier Inc. All rights reserved.

Physical properties of polyurethane plastic sheets produced from polyols from canola oil.

PubMed

Kong, Xiaohua; Narine, Suresh S

2007-07-01

Polyurethane (PUR) plastic sheets were prepared by reacting polyols synthesized from canola oil with aromatic diphenylmethane diisocyanate. The properties of the material were measured by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) as well as tensile properties measurements. The effect of stoichiometric balance (i.e., OH/NCO molar ratio) on the final properties was evaluated. The concentration of elastically active network chains (EANCs), nue, of the polymer networks was calculated using rubber elasticity theory. The glass transition temperatures (Tg) for the plastic sheets with OH/NCO molar ratios of 1.0/1.0, 1.0/1.1, and 1.0/1.2 were found to be 23, 41, and 43 degrees C, respectively. The kinetic studies of the degradation process of the PUR plastics showed three well-defined steps of degradation. The PUR plastic sheets with OH/NCO molar ratio 1.0/1.1 had the highest nue, lowest number-average molecule weight between cross-links, MC, and excellent mechanical properties, indicating that this is the optimum ratio in the PUR formulations.

Chemical Composition and Microhardness of Human Enamel Treated with Fluoridated Whintening Agents. A Study in Situ

PubMed Central

Petta, Thais de Mendonça; do Socorro Batista de Lima Gomes, Yasmin; Antunes Esteves, Renata; do Carmo Freitas Faial, Kelson; Souza D`Almeida Couto, Roberta; Martins Silva, Cecy

2017-01-01

Background: Dental whitening has been increasingly sought out to improve dental aesthetics, but may cause chemical and morphological changes in dental enamel surfaces. Objective: Assess in situ the effects of high-concentration hydrogen peroxide with and without fluoride on human dental enamel using the ion chromatography test (IC) and the Knoop hardness test (KHN). Material and Methods: Nineteen enamel specimens were prepared using third human molars. These specimens were fixed on molars of volunteers and were divided into groups: OP38-Opalescence Boost PF38%, PO37-Pola Office 37.5% and CO-Control group. For chemical analysis (n= 3), the dentin layer was removed, keeping only the enamel, which was subjected to acidic digestion by microwave radiation. It was necessary to perform sample dilutions for the elements fluorine (F), calcium (Ca) and phosphorus (P) for quantification using the IC test. The KHN (n= 5) was performed before and after the treatments. Five indentations were made, separated by 100 µm, for each specimen using a load of 25 gf for 5 seconds in the microdurometer. The data were analyzed using ANOVA with a 5% significance level. Results: The OP38 group had the largest concentrations of F, Ca and P ions. The PO37 group showed the lowest concentrations of F and Ca ions. The average KHN was not significantly different between the OP38 and PO37 groups. Conclusion: Enamel whitened with hydrogen peroxide containing fluoride had greater concentrations of F, Ca and P ions. The presence of fluoride in the whitening agent did not influence the enamel microhardness. PMID:28405245

Synthesis, characterization and biological approach of metal chelates of some first row transition metal ions with halogenated bidentate coumarin Schiff bases containing N and O donor atoms.

PubMed

Prabhakara, Chetan T; Patil, Sangamesh A; Toragalmath, Shivakumar S; Kinnal, Shivashankar M; Badami, Prema S

2016-04-01

The impregnation of halogen atoms in a molecule is an emerging trend in pharmaceutical chemistry. The presence of halogens (Cl, Br, I and F) increases the lipophilic nature of molecule and improves the penetration of lipid membrane. The presence of electronegative halogen atoms increases the bio- activity of core moiety. In the present study, Co(II), Ni(II) and Cu(II) complexes are synthesised using Schiff bases (HL(I) and HL(II)), derived from 8-formyl-7-hydroxy-4-methylcoumarin/3-chloro-8-formyl-7-hydroxy-4-methylcoumarin with 2,4-difluoroaniline/o-toluidine respectively. The synthesized compounds were characterized by spectral (IR, NMR, UV-visible, Mass, ESI-MS, ESR), thermal, fluorescence and molar conductivity studies. All the synthesized metal complexes are completely soluble in DMF and DMSO. The non-electrolytic nature of the metal complexes was confirmed by molar conductance studies. Elemental analysis study suggest [ML2(H2O)2] stoichiometry, here M=Co(II), Ni(II) and Cu(II), L=deprotonated ligand. The obtained IR data supports the binding of metal ion to Schiff base. Thermal study suggests the presence of coordinated water molecules. Electronic spectral results reveal six coordinated geometry for the synthesized metal complexes. The Schiff bases and their metal complexes were evaluated for antibacterial (Pseudomonas aureginosa and Proteus mirabilis), antifungal (Aspergillus niger and Rhizopus oryzae), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activities. Copyright © 2016 Elsevier B.V. All rights reserved.

BoneCeramic graft regenerates alveolar defects but slows orthodontic tooth movement with less root resorption.

PubMed

Ru, Nan; Liu, Sean Shih-Yao; Bai, Yuxing; Li, Song; Liu, Yunfeng; Wei, Xiaoxia

2016-04-01

BoneCeramic (Straumann, Basel, Switzerland) can regenerate bone in alveolar defects after tooth extraction, but it is unknown whether it is feasible to move a tooth through BoneCeramic grafting sites. The objective of this study was to investigate 3-dimensional real-time root resorption and bone responses in grafted sites during orthodontic tooth movement. Sixty 5-week-old rats were randomly assigned to 3 groups to receive BoneCeramic, natural bovine cancellous bone particles (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland), or no graft, after the extraction of the maxillary left first molar. After 4 weeks, the maxillary left second molar was moved into the extraction site for 28 days. Dynamic bone microstructures and root resorption were evaluated using in-vivo microcomputed tomography. Stress distribution and corresponding tissue responses were examined by the finite element method and histology. Mixed model analysis of variance was performed to compare the differences among time points with Bonferroni post-hoc tests at the significance level of P <0.05. The BoneCeramic group had the least amount of tooth movement and root resorption volumes and craters, and the highest bone volume fraction, trabecular number, and mean trabecular thickness, followed by the Bio-Oss and the control groups. The highest stress accumulated in the cervical region of the mesial roots. BoneCeramic has better osteoconductive potential and induces less root resorption compared with Bio-Oss grafting and naturally recovered extraction sites. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Preparation, characterization and cytotoxicity studies of some transition metal complexes with ofloxacin and 1,10-phenanthroline mixed ligand

NASA Astrophysics Data System (ADS)

Sadeek, S. A.; El-Hamid, S. M. Abd

2016-10-01

[Zn(Ofl)(Phen)(H2O)2](CH3COO)·2H2O (1), [ZrO(Ofl)(Phen)(H2O)]NO3·2H2O (2) and [UO2(Ofl)(Phen)(H2O)](CH3COO)·H2O (3) complexes of fluoroquinolone antibacterial agent ofloxacin (HOfl), containing a nitrogen donor heterocyclic ligand, 1,10-phenathroline monohydrate (Phen), were prepared and their structures were established with the help of elemental analysis, molar conductance, magnetic properties, thermal studies and different spectroscopic studies like IR, UV-Vis., 1H NMR and Mass. The IR data of HOfl and Phen ligands suggested the existing of a bidentate binding involving carboxylate O and pyridone O for HOfl ligand and two pyridine N atoms for Phen ligand. The coordination geometries and electronic structures are determined from electronic absorption spectra and magnetic moment measurements. From molar conductance studies reveals that metal complexes are electrolytes and of 1:1 type. The calculated bond length and force constant, F(Udbnd O), in the uranyl complex are 1.751 Å and 641.04 Nm-1. The thermal properties of the complexes were investigated by thermogravimetry (TGA) technique. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. Antimicrobial activity of the compounds was evaluated against some bacteria and fungi species. The activity data show that most metal complexes have antibacterial activity than that of the parent HOfl drug. The in vitro cytotoxicities of ligands and their complexes were also evaluated against human breast and colon carcinoma cells.

Local Application of Platelet-Rich Fibrin During Lower Third Molar Extraction Improves Treatment Outcomes.

PubMed

He, Yun; Chen, Junliang; Huang, Yue; Pan, Qin; Nie, Minhai

2017-12-01

Application of platelet-rich fibrin (PRF) during tooth extraction is able to accelerate wound healing, stimulate osseous and soft tissue regeneration, and reduce unwanted side effects. The aim of this meta-analysis was to investigate the effect of local application of PRF on controlling postoperative signs and symptoms after the extraction of an impacted lower third molar. A systematic search of PubMed, Web of Science, Embase, and the Cochrane Library was performed to identify all studies published up to October 2016 that investigated the effect of PRF on lower third molar extraction. Pain, swelling, trismus, alveolar osteitis (AO), and osteoblastic activity were extracted to evaluate the effect of PRF. After quality assessment, meta-analysis was performed with RevMan software (version 5.3; Cochrane Library Software, Oxford, UK). After the search and selection process, 10 studies were selected in this meta-analysis, including 468 cases of PRF application and 467 cases of non-PRF application. Of the studies, 9 were randomized controlled trials, including 7 split-mouth studies, and there was 1 retrospective case-control study. The results indicated that PRF significantly relieves pain (P = .01) and 3-day postoperative swelling (P = .03) and reduces the incidence of AO (P < .0001). However, there were no significant differences between the PRF and non-PRF groups with respect to 1-day postoperative swelling and osteoblastic activity. Local application of PRF after lower third molar extraction is a valid method for relieving pain and 3-day postoperative swelling and reducing the incidence of AO. For patients undergoing complicated surgical extraction, PRF might be a recommendation for local application into the sockets. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Size-distribution analysis of macromolecules by sedimentation velocity ultracentrifugation and lamm equation modeling.

PubMed

Schuck, P

2000-03-01

A new method for the size-distribution analysis of polymers by sedimentation velocity analytical ultracentrifugation is described. It exploits the ability of Lamm equation modeling to discriminate between the spreading of the sedimentation boundary arising from sample heterogeneity and from diffusion. Finite element solutions of the Lamm equation for a large number of discrete noninteracting species are combined with maximum entropy regularization to represent a continuous size-distribution. As in the program CONTIN, the parameter governing the regularization constraint is adjusted by variance analysis to a predefined confidence level. Estimates of the partial specific volume and the frictional ratio of the macromolecules are used to calculate the diffusion coefficients, resulting in relatively high-resolution sedimentation coefficient distributions c(s) or molar mass distributions c(M). It can be applied to interference optical data that exhibit systematic noise components, and it does not require solution or solvent plateaus to be established. More details on the size-distribution can be obtained than from van Holde-Weischet analysis. The sensitivity to the values of the regularization parameter and to the shape parameters is explored with the help of simulated sedimentation data of discrete and continuous model size distributions, and by applications to experimental data of continuous and discrete protein mixtures.

Formation of low charge state ions of synthetic polymers using quaternary ammonium compounds.

PubMed

Nasioudis, Andreas; Joyce, William F; van Velde, Jan W; Heeren, Ron M A; van den Brink, Oscar F

2010-07-01

Factors such as high polymer dispersity and variation in elemental composition (of copolymers) often complicate the electrospray ionization mass spectrometry (ESI-MS) analysis of synthetic polymers with high molar mass. In the experiments described in this study, quaternary ammonium compounds were observed to facilitate the production of low charge state pseudomolecular ions when added to the spray solution for ESI-MS. This approach was then used for the ESI time-of-flight mass spectrometry (TOF-MS) analysis of synthetic polymers. Hexadecyltrimethylammonium chloride permitted the successful analysis of poly(ethylene glycol) of 2-40 kDa, poly(propylene glycol) and poly(tetramethylene glycol) oligomers. Increasing the quaternary ammonium compounds' concentration results in the production of low charge state pseudomolecular ions. A comparison of structurally different quaternary ammonium compounds showed that the best performance is expected from large molecules with specific charge localization, which leaves the charge available for interactions. The applicability of the method for the MS analysis of other polymeric systems was also studied. In the case of poly(tetramethylene glycol), the method not only shifted the distributions to higher m/z values but also allowed the detection of high molecular weight material that was not observed without addition of the modifier to the spray solution.

Influence of Number of Implants and Attachment Type on Stress Distribution in Mandibular Implant-Retained Overdentures: Finite Element Analysis

PubMed Central

El-Anwar, Mohamed I.; El-Taftazany, Eman A.; Hamed, Hamdy A.; ElHay, Mohamed A. Abd

2017-01-01

AIM: This study aimed to compare the stresses generated by using two or four root form dental implants supporting mandibular overdentures that were retained with ball and locator attachments. METHODS: Under ANSYS environment, four 3D finite element models were prepared. These models simulated complete overdentures supported by two or four implants with either ball or locator attachments as a connection mechanism. The models’ components were created by CAD/CAM package then were imported to ANSYS. Load of 100 N was applied at the right premolar/molar region vertically and at an oblique angle of 110° from lingual direction. RESULTS: Within the conditions of this research, in all cases, it was found that cortical and cancellous bone regions were the least to be stressed. Also, the ball attachment produced higher stresses. CONCLUSION: Caps deformation and stresses are negligible in cases of using locator attachment in comparison to ball attachments. This may indicate longer lifetime and less repair/maintenance operations in implant overdentures retained by locator attachments. Although the study revealed that bone was insensitive to a number of implants or attachment type, it may be recommended to use two implants in the canine region than using four, where the locator attachments were found to be better. PMID:28507636

Influence of Number of Implants and Attachment Type on Stress Distribution in Mandibular Implant-Retained Overdentures: Finite Element Analysis.

PubMed

El-Anwar, Mohamed I; El-Taftazany, Eman A; Hamed, Hamdy A; ElHay, Mohamed A Abd

2017-04-15

This study aimed to compare the stresses generated by using two or four root form dental implants supporting mandibular overdentures that were retained with ball and locator attachments. Under ANSYS environment, four 3D finite element models were prepared. These models simulated complete overdentures supported by two or four implants with either ball or locator attachments as a connection mechanism. The models' components were created by CAD/CAM package then were imported to ANSYS. Load of 100 N was applied at the right premolar/molar region vertically and at an oblique angle of 110° from lingual direction. Within the conditions of this research, in all cases, it was found that cortical and cancellous bone regions were the least to be stressed. Also, the ball attachment produced higher stresses. Caps deformation and stresses are negligible in cases of using locator attachment in comparison to ball attachments. This may indicate longer lifetime and less repair/maintenance operations in implant overdentures retained by locator attachments. Although the study revealed that bone was insensitive to a number of implants or attachment type, it may be recommended to use two implants in the canine region than using four, where the locator attachments were found to be better.

Three-dimensional finite element analysis of the deformation of the human mandible: a preliminary study from the perspective of orthodontic mini-implant stability

PubMed Central

Baek, Sun-Hye; Cha, Hyun-Suk; Cha, Jung-Yul; Moon, Yoon-Shik

2012-01-01

Objective The aims of this study were to investigate mandibular deformation under clenching and to estimate its effect on the stability of orthodontic mini-implants (OMI). Methods Three finite element models were constructed using computed tomography (CT) images of 3 adults with different mandibular plane angles (A, low; B, average; and C, high). An OMI was placed between #45 and #46 in each model. Mandibular deformation under premolar and molar clenching was simulated. Comparisons were made between peri-orthodontic mini-implant compressive strain (POMI-CSTN) under clenching and orthodontic traction forces (150 g and 200 g). Results Three models with different mandibular plane angles demonstrated different functional deformation characteristics. The compressive strains around the OMI were distributed mesiodistally rather than occlusogingivally. In model A, the maximum POMI-CSTN under clenching was observed at the mesial aspect of #46 (1,401.75 microstrain [µE]), and similar maximum POMI-CSTN was observed under a traction force of 150 g (1,415 µE). Conclusions The maximum POMI-CSTN developed by clenching failed to exceed the normally allowed compressive cortical bone strains; however, additional orthodontic traction force to the OMI may increase POMI-CSTN to compromise OMI stability. PMID:23112947

Extraction and characterisation of apatite- and tricalcium phosphate-based materials from cod fish bones.

PubMed

Piccirillo, C; Silva, M F; Pullar, R C; Braga da Cruz, I; Jorge, R; Pintado, M M E; Castro, P M L

2013-01-01

Apatite- and tricalcium phosphate-based materials were produced from codfish bones, thus converting a waste by-product from the food industry into high added-valued compounds. The bones were annealed at temperatures between 900 and 1200 °C, giving a biphasic material of hydroxyapatite and tricalcium phosphate (Ca10(PO4)6(OH)2 and β-Ca(PO4)3) with a molar proportion of 75:25, a material widely used in biomedical implants. The treatment of the bones in solution prior to their annealing changed the composition of the material. Single phase hydroxyapatite, chlorapatite (Ca10(PO4)6Cl2) and fluorapatite (Ca10(PO4)6F2) were obtained using CaCl2 and NaF solutions, respectively. The samples were analysed by several techniques (X-ray diffraction, infrared spectroscopy, scanning electron microscopy and differential thermal/thermogravimetric analysis) and by elemental analyses, to have a more complete understanding of the conversion process. Such compositional modifications have never been performed before for these materials of natural origin to tailor the relative concentrations of elements. This paper shows the great potential for the conversion of this by-product into highly valuable compounds for biomedical applications, using a simple and effective valorisation process. Copyright © 2012 Elsevier B.V. All rights reserved.

Fractographic Analysis of a Split Tooth Presenting Radiographically as a Horizontal Root Fracture in an Unrestored Mandibular Second Molar.

PubMed

Krishnan, Unni; Moule, Alex; Michael, Shaji; Swain, Michael

2018-02-01

Spontaneously catastrophic fracture of intact unrestored molar teeth is not common. Nevertheless, cracks do occur that progress apically, resulting in the complete splitting of the tooth and root. This report describes a catastrophic fracture that occurred in an unrestored mandibular second molar resulting in a previously unreported combination of a longitudinal and horizontal root fracture, appearing radiographically as a single horizontal root fracture. Tooth fragments were examined clinically, stereoscopically, and by scanning electron microscopy. Fractographic analysis was used to investigate the dynamics involved in fracture initiation, structural resistances encountered during progression of the fracture, and reasons for direction changes culminating in the unusual radiographic appearance. The uniqueness of this report is that it describes fractographic evidence of factors contributing to the initiation and progression of an in vivo crack. It shows fracture markings that are evidence of the energy dissipation mechanisms. The topographic location of these markings confirmed that cracks occur in vivo in stages with different rates of progression. This analysis helps to explain why split teeth are uncommon and highlights some of the multitude of factors that have to coincide for a tooth to catastrophically fracture. The report describes the mechanism of fracture and should stimulate clinicians and researchers to investigate cracking of teeth by undertaking fractographic analysis of extracted cracked teeth. Copyright © 2017 American Association of Endodontists. All rights reserved.

Pharmacological Control of Complications Following to Third Molar Removal: Evidence Based on A Meta-Analysis.

PubMed

Isiordia-Espinoza, Mario Alberto; Bologna-Molina, Ronell Eduardo; Hernández-Miramontes, Ycenna Ailed; Zapata-Morales, Juan Ramón; Alonso-Castro, Angel Jobsabad; Martínez-Morales, Flavio; Sánchez-Enriquez, Sergio; Serafín-Higuera, Nicolás Addiel; Pérez-Cortez, Guillermo; Franco-de la Torre, Lorenzo

2018-06-26

The purpose of this meta-analysis was to evaluate the clinical efficacy of non-steroidal anti-inflammatory drugs and dexamethasone on the trismus, postsurgical pain, facial swelling, as well as the analgesic consumption after third molar surgery. The reports were identified in the most important medical databases. Those studies that met the requirements were fully assessed according to the inclusion and exclusion criteria. The quality of each report was evaluated with the Oxford Quality Scale and using the Cochrane Collaboration's risk of bias tool. Each meta-analysis was done using the technique of mean difference and 95% confidence intervals employing a random effects model with the Review Manager 5.3., from the Cochrane Library. Significant statistical difference was accepted when the p value was less than 0.05 on the test of overall effect (Z value). Qualitative evaluation was done using the data of 330 patients extracted from seven articles and the quantitative assessment with data of 200 patients from three reports. It was not observed difference among non-steroidal anti-inflammatory drugs and dexamethasone in any of the clinical effectiveness indicators. The outcomes of our meta-analysis indicate that non-steroidal anti-inflammatory drugs and dexamethasone have good therapeutic effect for the management of inflammatory complications following to third molar surgery. © Georg Thieme Verlag KG Stuttgart · New York.

AXIAL MODIFICATIONS OF PERMANENT LOWER MOLARS AFTER PREMATURE LOSSES OF TEMPORARY MOLARS.

PubMed

Cernei, E R; Mavru, R B; Zetu, Irina Nicoleta

2016-01-01

The aim of our study was to determine the impact of premature loss of temporary lower molars upon the longitudinal axis of the first and second permanent molars. The study groups included 61 patients, 6-9 year olds with premature loss of primary molars and a control group of 24 patients with intact temporary teeth. We evaluated the angle between longitudinal axis of first and second lower permanent molars and occlusal plane. It was observed that premature loss of lower second deciduous molar modifies more the vertical axis of first and second permanent molars than the premature loss of first lower primary molar. Reducing space occurs mainly through mesial inclination of molars that separates the edentulous breach. Temporary loss of both lower first molars on the same quadrant causes an accelerated eruption of both premolars increasing the prevalence of eruption sequence: "4-5-3-7". The preservation of the occlusal morpho-functional complex using space maintainers mainly when the premature loss of the second primary molars occurs is the best interceptive treatment option.

Zn-Al layered double hydroxide prepared at different molar ratios: Preparation, characterization, optical and dielectric properties

NASA Astrophysics Data System (ADS)

Ahmed, Abdullah Ahmed Ali; Talib, Zainal Abidin; bin Hussein, Mohd Zobir; Zakaria, Azmi

2012-07-01

The co-precipitation method was used to prepare Zn-Al-NO3-LDH at different Zn2+/Al3+ molar ratios (2, 3, 4, 5 and 6) and pH value of 7.5. The structure, textural, composition and morphological properties were investigated using powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) and scanning electron microscope (SEM), respectively. The crystallinity of LDH samples were found to improve as molar ratio decreased which is attributed to the distortion of the hydroxide layers networks of the LDH crystal by the larger difference in ionic radii of Zn2+ and Al3+. The optical band gap energy of LDH samples were evaluated using absorbance data from UV-Vis-NIR Diffuse reflectance spectroscopy. Band gaps were affected by the variation of the Zn2+/Al3+ molar ratio is due to the formation of the low crystalline phases (ZnO and ZnAl2O4). The water molecules and anionic NO3- in the LDH interlayer were responsible for the generation of the dielectric response. This response can be described by an anomalous low frequency dispersion using the second type of Universal Power Law. The dominance of ZnO dipoles and charge carriers (NO3- ions) in the dielectric relaxation increases with the increasing molar ratio.

Calculation extinction cross sections and molar attenuation coefficient of small gold nanoparticles and experimental observation of their UV-vis spectral properties

NASA Astrophysics Data System (ADS)

Tang, Junqi; Gao, Kunpeng; Ou, Quanhong; Fu, Xuewen; Man, Shi-Qing; Guo, Jie; Liu, Yingkai

2018-02-01

Gold nanoparticles (AuNPs) have been researched extensively, such as applied in various biosensors, biomedical imaging and diagnosis, catalysis and physico-chemical analysis. These applications usually required to know the nanoparticle size or concentration. Researchers have been studying a simply and quick way to estimate the concentration or size of nanoparticles from their optical spectra and SPR feature for several years. The extinction cross-sections and the molar attenuation coefficient were one of the key parameters. In this study, we calculated the extinction cross-sections and molar attenuation coefficient (decadic molar extinction coefficient) of small gold nanoparticles by dipole approximation method and modified Beer-Lambert law. The theoretical result showed that the surface plasmon resonance peak of small gold nanoparticles was blueshift with an increase size. Moreover, small AuNPs (sub-10 nm) were prepared by using of dextran or trisodium citrate as reducing agent and capping agent. The experimental synthesized AuNPs was also shows a blueshift as increasing particle size in a certain range. And the concentration of AuNPs was calculated based on the obtained molar attenuation coefficient. For small nanoparticles, the size of nanoparticles and surface plasmon resonance property was not showed a positive correlation compared to larger nanoparticles. These results suggested that SPR peak depended not only on the nanoparticle size and shape but also on the nanoparticles environment.

Early extraction of the mandibular third molar in case of eruption disturbances of the second molar.

PubMed

Kavadia, S; Antoniades, K; Kaklamanos, E; Antoniades, V; Markovitsi, E; Zafiriadis, L

2003-01-01

General consensus has been reached on extracting mandibular third molars when they are involved in pathologic processes. However, early extraction is advisable in cases of eruption disturbances of the mandibular second molar, before or during orthodontic treatment. Thirty-two patients with early extraction of the mandibular third molar before or during orthodontic treatment were examined. In these cases either the presence of the third molar presented an obstacle in the eruption path of the second, or third molar germ removal was considered beneficial to the course of orthodontic treatment. Early extraction of the mandibular third molar facilitates the eruption of the second molar, especially in cases where evidence of crowding and lack of space in the posterior mandibular region exist. Orthodontic treatment may, in some cases, aggravate eruption disturbances of the second molar.

Influence of third molar space on angulation and dental arch crowding.

PubMed

Hasegawa, Yuh; Terada, Kazuto; Kageyama, Ikuo; Tsuchimochi, Takashi; Ishikawa, Fujiro; Nakahara, Sen

2013-01-01

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding.

Use of cone beam computed tomography to assess significant imaging findings related to mandibular third molar impaction.

PubMed

Matzen, Louise Hauge; Schropp, Lars; Spin-Neto, Rubens; Wenzel, Ann

2017-11-01

The aim of the study was to identify risk factors for pathoses related to mandibular third molars observed in cone beam computed tomography. Cone beam computed tomography volumes of 410 mandibular third molars were assessed by 3 observers, according to the angulation and position of the third molar in relation to the second molar. In addition, pathoses (marginal bone loss, resorption of the second molar, increased follicular space and lingual bone perforation) were assessed. Logistic regression analyses were used to test whether the angulation and position of the third molar were risk factors for pathoses. On average, 41% of second molars had resorption; mesioangulated (odds ratio [OR] 11-107; P < .001) and horizontally positioned (OR 13-120; P < .001) third molars located cervically at the second molar (OR 2-3; P < .027) significantly increased the risk. On average, 49% of second molars had marginal bone loss; mesioangulated (OR 16-85; P < .001) and horizontally positioned (OR 61-573; P < .001) third molars increased the risk. For the third molar, an increased follicular space was seen in 25% of cases; distal (OR 5-9; P < .001) and vertical positions (OR 5; P < .002) increased the risk. Lingual bone perforation was not related to a specific angulation. Specific angulations of the mandibular third molar are risk factors for marginal bone loss and resorption of the second molar. Copyright © 2017 Elsevier Inc. All rights reserved.

Efficacy of amoxicillin and amoxicillin/clavulanic acid in the prevention of infection and dry socket after third molar extraction. A systematic review and meta-analysis.

PubMed

Arteagoitia, M-I; Barbier, L; Santamaría, J; Santamaría, G; Ramos, E

2016-07-01

Prophylactic use of amoxicillin and amoxicillin/clavulanic acid, although controversial, is common in routine clinical practice in third molar surgery. Our objective was to assess the efficacy of prophylactic amoxicillin with or without clavulanic acid in reducing the incidence of dry socket and/or infection after third molar extraction. We conducted a systematic review and meta-analysis consulting electronic databases and references in retrieved articles. We included double-blind placebo-controlled randomized clinical trials published up to June 2015 investigating the efficacy of amoxicillin with or without clavulanic acid on the incidence of the aforementioned conditions after third molar extraction. Relative risks (RRs) were estimated with a generic inverse-variance approach and a random effect model using Stata/IC 13 and Review Manager Version 5.2. Stratified analysis was performed by antibiotic type. We included 10 papers in the qualitative review and in the quantitative synthesis (1997 extractions: 1072 in experimental groups and 925 in controls, with 27 and 74 events of dry socket and/or infection, respectively). The overall RR was 0.350 (p<0.001; 95% CI 0.214 to 0.574). We found no evidence of heterogeneity (I2=0%, p=0.470). The number needed to treat was 18 (95% CI 13 to 29). Five studies reported adverse reactions (RR=1.188, 95% CI 0.658 to 2.146, p =0.567). The RRs were 0.563 for amoxicillin (95% CI 0.295 to 1.08, p=0.082) and 0.215 for amoxicillin/clavulanic acid (95% CI 0.117 to 0.395, p<0.001). Prophylactic use of amoxicillin does not significantly reduce the risk of infection and/or dry socket after third molar extraction. With amoxicillin/clavulanic acid, the risk decreases significantly. Nevertheless, considering the number needed to treat, low prevalence of infection, potential adverse reactions to antibiotics and lack of serious complications in placebo groups, the routine prescription of amoxicillin with or without clavulanic acid is not justified.

Behavior dynamics: One perspective

PubMed Central

Marr, M. Jackson

1992-01-01

Behavior dynamics is a field devoted to analytic descriptions of behavior change. A principal source of both models and methods for these descriptions is found in physics. This approach is an extension of a long conceptual association between behavior analysis and physics. A theme common to both is the role of molar versus molecular events in description and prediction. Similarities and differences in how these events are treated are discussed. Two examples are presented that illustrate possible correspondence between mechanical and behavioral systems. The first demonstrates the use of a mechanical model to describe the molar properties of behavior under changing reinforcement conditions. The second, dealing with some features of concurrent schedules, focuses on the possible utility of nonlinear dynamical systems to the description of both molar and molecular behavioral events as the outcome of a deterministic, but chaotic, process. PMID:16812655

Effect of restoration volume on stresses in a mandibular molar: a finite element study.

PubMed

Wayne, Jennifer S; Chande, Ruchi; Porter, H Christian; Janus, Charles

2014-10-01

There can be significant disagreement among dentists when planning treatment for a tooth with a failing medium-to-large--sized restoration. The clinician must determine whether the restoration should be replaced or treated with a crown, which covers and protects the remaining weakened tooth structure during function. The purpose of this study was to evaluate the stresses generated in different sized amalgam restorations via a computational modeling approach and reveal whether a predictable pattern emerges. A computer tomography scan was performed of an extracted mandibular first molar, and the resulting images were imported into a medical imaging software package for tissue segmentation. The software was used to separate the enamel, dentin, and pulp cavity through density thresholding and surface rendering. These tissue structures then were imported into 3-dimensional computer-aided design software in which material properties appropriate to the tissues in the model were assigned. A static finite element analysis was conducted to investigate the stresses that result from normal occlusal forces. Five models were analyzed, 1 with no restoration and 4 with increasingly larger restoration volume proportions: a normal-sized tooth, a small-sized restoration, 2 medium-sized restorations, and 1 large restoration as determined from bitewing radiographs and occlusal surface digital photographs. The resulting von Mises stresses for dentin-enamel of the loaded portion of the tooth grew progressively greater as the size of the restoration increased. The average stress in the normal, unrestored tooth was 4.13 MPa, whereas the smallest restoration size increased this stress to 5.52 MPa. The largest restoration had a dentin-enamel stress of 6.47 MPa. A linear correlation existed between restoration size and dentin-enamel stress, with an R(2) of 0.97. A larger restoration volume proportion resulted in higher dentin-enamel stresses under static loading. A comparison of the von Mises stresses to the yield strengths of the materials revealed a relationship between a tooth's restoration volume proportion and the potential for failure, although factors other than restoration volume proportion may also impact the stresses generated in moderate-sized restorations. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Dental wear, wear rate, and dental disease in the African apes.

PubMed

Elgart, Alison A

2010-06-01

The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin-enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin-enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample.

Postoperative socket irrigation with drinking tap water reduces the risk of inflammatory complications following surgical removal of third molars: a multicenter randomized trial.

PubMed

Ghaeminia, H; Hoppenreijs, Th J M; Xi, T; Fennis, J P; Maal, T J; Bergé, S J; Meijer, G J

2017-01-01

The primary aim of the present study was to evaluate the effectiveness of postoperative irrigation of the socket with drinking tap water on inflammatory complications following lower third molar removal. A multicenter randomized controlled trial was carried out from June 2013 to June 2014. In one arm of the study, patients were instructed to irrigate the tooth socket and surgical site with a Monoject® Curved 412 Tip Syringe (Tyco/healthcare-Kendall, Mansfield, MA, USA) with tap water. In a second arm of the study, the standard postoperative instructions did not include irrigation instructions. The incidences of alveolar osteitis and wound infection were recorded for each group and analyzed by the Fisher's exact test. A total of 280 patients with 333 mandibular third molars were analyzed. According to the intention-to-treat (ITT) analysis, inflammatory complications occurred in 18 cases in the Monoject® group (11.4 %) compared to 34 cases (19.1 %) in the control group (p = 0.04). These complications were associated with significant worse outcomes regarding quality of life, pain, and trismus and caused significantly more missed days of work or study. Female gender, age >26, bone removal, deep impacted third molars, less experienced surgeons, and a high amount of debris at the surgical site were also identified as risk factors for developing inflammatory complications following lower third molar removal. Irrigation of the surgical site with drinking tap water using a curved syringe following removal of third molars is effective in reducing the risk of inflammatory complications. Water is a very accessible, cost-effective irrigant without side effects and the results from this study have proven that it can be used to reduce the risk of inflammatory complications and associated morbidity following lower third molar removal.

Prevalence and morphometric analysis of three-rooted mandibular first molars in a Brazilian subpopulation

PubMed Central

Rodrigues, Clarissa Teles; de Oliveira-Santos, Christiano; Bernardineli, Norberti; Duarte, Marco Antonio Hungaro; Bramante, Clovis Monteiro; Minotti-Bonfante, Paloma Gagliardi; Ordinola-Zapata, Ronald

2016-01-01

ABSTRACT The knowledge of the internal anatomy of three-rooted mandibular molars may help clinicians to diagnose and plan the root canal treatment in order to provide adequate therapy when this variation is present. Objectives: To determine the prevalence of three-rooted mandibular molars in a Brazilian population using cone beam computed tomography (CBCT) and to analyze the anatomy of mandibular first molars with three roots through micro-CT. Material and Methods: CBCT images of 116 patients were reviewed to determine the prevalence of three-rooted first mandibular molars in a Brazilian subpopulation. Furthermore, with the use of micro-CT, 55 extracted three-rooted mandibular first molars were scanned and reconstructed to assess root length, distance between canal orifices, apical diameter, Vertucci's classification, presence of apical delta, number of foramina and furcations, lateral and accessory canals. The distance between the orifice on the pulp chamber floor and the beginning of the curvature and the angle of canal curvature were analyzed in the distolingual root. Data were compared using the Kruskal-Wallis test (α=0.05). Results: The prevalence of three-rooted mandibular first molars was of 2.58%. Mesial roots showed complex distribution of the root canal system in comparison to the distal roots. The median of major diameters of mesiobuccal, mesiolingual and single mesial canals were: 0.34, 0.41 and 0.60 mm, respectively. The higher values of major diameters were found in the distobuccal canals (0.56 mm) and the lower diameters in the distolingual canals (0.29 mm). The lowest orifice distance was found between the mesial canals (MB-ML) and the highest distance between the distal root canals (DB-DL). Almost all distal roots had one root canal and one apical foramen with few accessory canals. Conclusions: Distolingual root generally has short length, severe curvature and a single root canal with low apical diameter. PMID:27812625

Taking advantage of an unerupted third molar: a case report.

PubMed

Pereira, Igor Figueiredo; Santiago, Fernando Zander Mucci; Sette-Dias, Augusto Cesar; Noronha, Vladimir Reimar Augusto de Souza

2017-01-01

Treatments with dental surgery seek to displace tooth to the correct position within the dental arch. To report a clinical case that took advantage of an unerupted third molar. A male patient, 18 years of age, was referred by his dentist to evaluate the third molars. The clinical exam revealed no visible lower third molars. The computed tomography (CT) exam showed the presence of a supernumerary tooth in the region of the mandibular ramus, on the left side, and impaction of the third molar, which was causing root resorption on the second molar, thus making it impossible to remain in the buccal cavity. The preferred option, therefore, was to remove both second molar and the supernumerary tooth, in addition to attaching a device to the third molar during surgery for further traction. After 12 months, the third molar reached the proper position. When a mandibular second permanent molar shows an atypical root resorption, an impacted third molar can effectively substitute the tooth by using an appropriate orthodontic-surgical approach.

Bilateral maxillary fused second and third molars: a rare occurrence

PubMed Central

Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

2012-01-01

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months. PMID:23222992

Bilateral maxillary fused second and third molars: a rare occurrence.

PubMed

Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

2012-12-01

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months.

Correlation of root dentin thickness and length of roots in mesial roots of mandibular molars.

PubMed

Dwivedi, Shweta; Dwivedi, Chandra Dhar; Mittal, Neelam

2014-09-01

The purpose of this study was to analyze the relation of tooth length and distal wall thickness of mesial roots in mandibular molars at different locations (ie, 2 mm below the furcation and at the junction between the middle and apical third). Forty-five mandibular first molars were taken, and the length of each tooth was measured. Then, specimens were divided into three groups according to their length: group I-long (24.2 mm ± 1.8), group II-medium (21 mm ± 1.5) and group III-short (16.8 mm ± 1.8). mesial root of each marked at two levels - at 2 mm below the furcation as well as at junction of apical and middle third of roots. The minimum thickness of the distal root dentine associated with the buccal and lingual canals of the mesial roots was measured, The distance between the buccal and lingual canals and the depth of concavity in the distal surface of the mesial roots were also measured. Statistical analysis was performed by using analysis of variance and the Student-Newman-Keuls test. The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < .001) between groups 1 (long) and 3 (short). Distal wall thickness of the mesiobuccal root and distal concavity of the mesial root of mandibular first molars were found to be thinner in longer teeth compared with shorter teeth. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Endodontic management of a mandibular third molar fused with a fourth molar.

PubMed

Turell, I L; Zmener, O

1999-05-01

Developmental anomalies in permanent molars frequently require surgical intervention. A case of a mandibular third molar fused with a fourth molar which was successfully treated with conservative endodontic therapy is reported.

Size variation in early human mandibles and molars from Klasies River, South Africa: comparison with other middle and late Pleistocene assemblages and with modern humans.

PubMed

Royer, Danielle F; Lockwood, Charles A; Scott, Jeremiah E; Grine, Frederick E

2009-10-01

Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best-represented elements at the site, namely the mandibular corpora and M(2)s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skhūl, Dolní Vestonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skhūl, Dolní Vestonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis.

Immobilization of Eu and Ho from synthetic acid mine drainage by precipitation with Fe and Al (hydr)oxides.

PubMed

Barcelos, Gisely S; Veloso, Renato Welmer; de Mello, Jaime W V; Gasparon, Massimo

2018-04-30

Use of lime to mitigate acid mine drainage is, in general, accompanied by precipitation of iron (Fe) and aluminium (Al) (hydr)oxides which may increase the removal of trace elements from water. This work aimed to evaluate the precipitation of Fe/Al (hydr)oxides to remove rare earth elements (REE) from contaminated water and the stability of precipitates. Two sets of 60-day syntheses were carried out using different Fe/Al/REE molar ratios, for europium (Eu) and holmium (Ho). The pH was periodically adjusted to 9.0, and the stability of the resulting precipitates was evaluated by water-soluble and BCR extractable phases, namely (1) acid soluble, extracted by 0.11 mol L -1 acetic acid; (2) reducible, extracted with 0.5 mol L -1 hydroxylamine hydrochloride; and (3) oxidisable, extracted with 8.8 mol L -1 hydrogen peroxide efficiencies of the water treatments for both Eu and Ho that were higher than 99.9% irrespective to the Fe/Al/REE molar ratios. Water-soluble phases of Eu and Ho were lower than 0.01% of the total contents in the precipitates. Recoveries from precipitates by Bureau Communautaire de Référence (BCR) sequential extractions increased with increasing concentrations of Eu and Ho. Acetic acid extracted higher amounts of REE, but Eu recovery was superior to Ho. Lepidocrocite was formed as Eu concentration increased which decreased its stability in the precipitates.

An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques.

PubMed

Abu-Alhaija, Elham; Jaradat, Mohammad; Alwahadni, Ahed

2017-03-01

Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18% hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes. The bond strength testing was performed using a computer control electromechanical universal testing machine. The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and 13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and the addition of silane (group 4) produced bond strength values comparable to the control. Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups. Key words: Molar, shear strength, tensile strength, orthodontic appliances.

An Ex-vivo Shear and tensile bond strengths of orthodontic molar tubes bonded using different techniques

PubMed Central

Alwahadni, Ahed

2017-01-01

Background Molar bonding procedures need continuous improvement to be widely accepted clinically and eventually replace molar bands. Material and Methods The purpose of this study was to determine the effects of enamel micro-abrasion and silane coating of the base of molar tubes on shear and tensile bond strengths of orthodontic molar tubes. A total of 200 third molars were randomly allocated into five groups of 40 teeth as follows: group 1: molar tubes bonded to etched teeth (37% phosphoric acid gel; control group); group 2: molar tubes bonded to etched teeth (37% phosphoric acid) with the addition of silane to the base of molar tubes; group 3: molar tubes bonded to teeth pre-treated with 18% hydrochloric acid and pumice (micro-abrasion); group 4: molar tubes bonded to teeth pre-treated with microabrasion with the addition of silane to the base of molar tubes; group 5: molar tubes bonded to teeth pre-treated with microabrasion before conventional acid etching combined with the addition of silane to the base of molar tubes. The bond strength testing was performed using a computer control electromechanical universal testing machine. Results The highest mean shear and tensile bond strengths were recorded in group 5 (13.81±2.54MPa and 13.97±2.29 MPa, respectively). Micro-abrasion alone (group 3) and the combination of enamel micro-abrasion and the addition of silane (group 4) produced bond strength values comparable to the control. Conclusions Enamel surface pre-treatment (micro abrasion) before conventional acid etching combined with the addition of silane to the base of the molar tube produced the highest bond strengths among all tested groups. Key words:Molar, shear strength, tensile strength, orthodontic appliances. PMID:28298990

Relationship between mandibular condyle and angle fractures and the presence of mandibular third molars.

PubMed

Mah, Deuk-Hyun; Kim, Su-Gwan; Moon, Seong-Yong; Oh, Ji-Su; You, Jae-Seek

2015-02-01

We retrospectively evaluated the impact of mandibular third molars on the occurrence of angle and condyle fractures. This was a retrospective investigation using patient records and radiographs. The sample set consisted of 440 patients with mandibular fractures. Eruption space, depth and angulation of the third molar were measured. Of the 144 angle fracture patients, 130 patients had third molars and 14 patients did not. The ratio of angle fractures when a third molar was present (1.26 : 1) was greater than when no third molar was present (0.19 : 1; odds ratio, 6.58; P<0.001). Of the 141 condyle fractures patients, the third molar was present in 84 patients and absent in 57 patients. The ratio of condyle fractures when a third molar was present (0.56 : 1) was lower than when no third molar was present (1.90 : 1; odds ratio, 0.30; P<0.001). The increased ratio of angle fractures with third molars and the ratio of condyle fractures without a third molar were statistically significant. The occurrence of angle and condyle fractures was more affected by the continuity of the cortical bone at the angle than by the depth of a third molar. These results demonstrate that a third molar can be a determining factor in angle and condyle fractures.