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Sample records for dental restorative composites

  1. Confined compression of dental composites for Class I restorations

    PubMed Central

    Patki, Amol S.; Vural, Murat; Gosz, Mike

    2011-01-01

    This study focuses on the mechanical response of a particle-reinforced restorative dental composite (Renew™) under proportional transverse confinement to understand the effects of stress multiaxiality on its mechanical and failure behaviors. We describe the confining ring technique as an experimental tool to introduce multiaxial compressive stress states in dental composites that realistically mimic three-dimensional stress states commonly experienced by dental restorations in the oral cavity. Effect of initial radial misfit between confining ring and specimen is analyzed through computational finite element simulations, and an analytical treatment of problem is also provided to compute the confining stress during elasto-plastic expansion of confining ring. Experimental results suggest that inelastic response of Renew composite is significantly influenced by hydrostatic stress component, and pressure-dependent yield functions are required to analyze plastic deformations and internal damage accumulation process. PMID:21857744

  2. Recent Advances and Developments in Composite Dental Restorative Materials

    PubMed Central

    Cramer, N.B.; Stansbury, J.W.; Bowman, C.N.

    2011-01-01

    Composite dental restorations represent a unique class of biomaterials with severe restrictions on biocompatibility, curing behavior, esthetics, and ultimate material properties. These materials are presently limited by shrinkage and polymerization-induced shrinkage stress, limited toughness, the presence of unreacted monomer that remains following the polymerization, and several other factors. Fortunately, these materials have been the focus of a great deal of research in recent years with the goal of improving restoration performance by changing the initiation system, monomers, and fillers and their coupling agents, and by developing novel polymerization strategies. Here, we review the general characteristics of the polymerization reaction and recent approaches that have been taken to improve composite restorative performance. PMID:20924063

  3. A novel antibacterial resin composite for improved dental restoratives.

    PubMed

    Weng, Yiming; Howard, Leah; Guo, Xia; Chong, Voon Joe; Gregory, Richard L; Xie, Dong

    2012-06-01

    A novel furanone-containing antibacterial resin composite has been prepared and evaluated. compressive strength (CS) and Streptococcus mutans viability were used to evaluate the mechanical strength and antibacterial activity of the composites. The modified resin composites showed a significant antibacterial activity without substantially decreasing the mechanical strengths. With 5-30 % addition of the furanone derivative, the composite kept its original CS unchanged but showed a significant antibacterial activity with a 16-68 % reduction in the S. mutans viability. Further, the antibacterial function of the new composite was not affected by human saliva. The aging study indicates that the composite may have a long-lasting antibacterial function. Within the limitations of this study, it appears that the experimental antibacterial resin composite may potentially be developed into a clinically attractive dental restorative due to its high mechanical strength and antibacterial function. PMID:22466818

  4. Mechanical performance of novel bioactive glass containing dental restorative composites

    PubMed Central

    Khvostenko, D.; Mitchell, J. C.; Hilton, T. J.; Ferracane, J. L.; Kruzic, J. J.

    2013-01-01

    Objectives Bioactive glass (BAG) is known to possess antimicrobial properties and release ions needed for remineralization of tooth tissue, and therefore may be a strategic additive for dental restorative materials. The objective of this study was to develop BAG containing dental restorative composites with adequate mechanical properties comparable to successful commercially available composites, and to confirm the stability of these materials when exposed to a biologically challenging environment. Methods Composites with 72 wt.% total filler content were prepared while substituting 0–15% of the filler with ground BAG. Flexural strength, fracture toughness, and fatigue crack growth tests were performed after several different soaking treatments: 24 hours in DI water (all experiments), two months in brain-heart infusion (BHI) media+S. mutans bacteria (all experiments) and two months in BHI media (only for flexural strength). Mechanical properties of new BAG composites were compared along with the commercial composite Heliomolar by two-way ANOVA and Tukey’s multiple comparison test (p≤0.05). Results Flexural strength, fracture toughness, and fatigue crack growth resistance for the BAG containing composites were unaffected by increasing BAG content up to 15% and were superior to Heliomolar after all post cure treatments. The flexural strength of the BAG composites was unaffected by two months exposure to aqueous media and a bacterial challenge, while some decreases in fracture toughness and fatigue resistance were observed. The favorable mechanical properties compared to Heliomolar were attributed to higher filler content and a microstructure morphology that better promoted the toughening mechanisms of crack deflection and bridging. Significance Overall, the BAG containing composites developed in this study demonstrated adequate and stable mechanical properties relative to successful commercial composites. PMID:24050766

  5. Teaching the placement of posterior resin-based composite restorations in Spanish dental schools

    PubMed Central

    Lynch, Christopher; McConnell, Robert; Wilson, Nairn

    2012-01-01

    Objectives: In an area of esthetic dentistry such as posterior composites, in which new materials and techniques are being devolved continuously, it is important to confirm that dental students have a clear understanding of the basic principles of clinical application of this knowledge. Considering that the preparation of dental graduates in Spain may be of interest to competent dental authorities and employers with whom they can work worldwide, this study investigated the teaching of posterior composite restorations in Spanish dental schools. Study design: In late 2009⁄ early 2010, a questionnaire seeking information on the teaching of posterior composites was emailed to the professor responsible for teaching operative dentistry in each of the fifteen dental schools having complete undergraduate dental degree programs in Spain. Results: The response rate was 100%. Most investigated topics did not show noteworthy differences depending on whether the schools were public or private. Variations were found among Spanish dental schools in both the amount and content of the teaching programs concerning posterior composite restorations. Differences were recorded in the teaching of cavity design, contraindications to composite placement, indications for liners and bases, matrix and wedging techniques, composite and bonding systems, light curing and finishing procedures for composite restorations. More consistency was observed in teaching methods of moisture-control, indirect composites and amalgam bonding. Conclusions: As recommended in previously surveyed countries, efforts must be made to promote harmonization of dental curricula to make it easier for graduates to work elsewhere, and to ensure they meet the needs of their patients on entering independent practice. Key words:Aesthetic dentistry, composite restoration, dental education, teaching program, undergraduate dental student. PMID:22322491

  6. Perfluorotriethylene glycol dimethacrylate modified composite resins for improved dental restoratives

    NASA Astrophysics Data System (ADS)

    Wang, Guigui

    The studies described in this dissertation focus on improvement of water resistance and durability of current dental composite resins. The physical, thermal and mechanical properties of the diluent fluorinated monomer, perfluorotriethylene glycol methacrylate (FTEGDMA), FTEGDMA-containing neat resin and its formulated composite resins were evaluated and compared with the conventional visible light-cured (VLC) dental composite resins. Further, the biocompatibility of this monomer and its cured resins were investigated and compared with their conventional counterparts. The results showed that the FTEGDMA-containing neat resin and its composite systems showed more water resistance and longer durability, compared to the conventional Bisphenol A glycol dimethacrylate/triethylene glycol dimethacrylate (BisGMA/TEGDMA) system. The preliminary in vitro biocompatibility test showed that FTEGDMA favored cell growth, compared to the conventional dental resins. The first study investigated basic physical properties of the diluent FTEGDMA monomer. The results showed that the FTEGDMA exhibited lower viscosity, lower refractive index, and a smaller contact angle, which were all beneficial to lowering the water sorption and increasing hydrophobicity. The second study evaluated some physical, thermal, and mechanical properties of the FTEGDMA based neat resins, including polymerization shrinkage, contact angle, water sorption, glass-transitions, dynamic modulus, thermal expansion, compressive strength, and diametral tensile strength. The results showed that the FTEGDMA diluent exhibited significant less water sorption and lower polymerization shrinkage and the BisEMA also contributed towards reducing water sorption. The third study investigated the effects of the FTEGDMA on the mechanical properties of the composite resins including flexural strength (FS), diametral tensile strength (DTS) and wear resistance (WR). In addition, the fracture surface topography of the tested materials

  7. Effects of temperature change and beverage on mechanical and tribological properties of dental restorative composites.

    PubMed

    Ayatollahi, M R; Yahya, Mohd Yazid; Karimzadeh, A; Nikkhooyifar, M; Ayob, Amran

    2015-09-01

    The aim of this study was to investigate the effects of temperature change and immersion in two common beverages on the mechanical and tribological properties for three different types of dental restorative materials. Thermocycling procedure was performed for simulating temperature changes in oral conditions. Black tea and soft drink were considered for beverages. Universal composite, universal nanohybrid composite and universal nanofilled composite, were used as dental materials. The nanoindentation and nanoscratch experiments were utilized to determine the elastic modulus, hardness, plasticity index and wear resistance of the test specimens. The results showed that thermocycling and immersion in each beverage had different effects on the tested dental materials. The mechanical and tribological properties of nanohybrid composite and nanocomposite were less sensitive to temperature change and to immersion in beverages in comparison with those of the conventional dental composite. PMID:26046269

  8. Cytogenetic genotoxic investigation in peripheral blood lymphocytes of subjects with dental composite restorative filling materials.

    PubMed

    Pettini, F; Savino, M; Corsalini, M; Cantore, S; Ballini, A

    2015-01-01

    Dental composite resins are biomaterials commonly used to aesthetically restore the structure and function of teeth impaired by caries, erosion, or fracture. Residual monomers released from resin restorations as a result of incomplete polymerization processes interact with living oral tissues. The objective of this study was to evaluate the genotoxicity of a common dental composite material (Enamel Plus-HFO), in subjects with average 13 filled teeth with the same material, compared to a control group (subjects having neither amalgam nor composite resin fillings). Genotoxicity assessment of composite materials was carried out in vitro in human peripheral blood leukocytes using sister-chromatid exchange (SCE) and chromosomal aberrations (CA) cytogenetic tests. The results of correlation and multiple regression analyses confirmed the absence of a relationship between SCE/cell, high frequency of SCE(HFC) or CA frequencies and exposure to dental composite materials. These results indicate that composite resins used for dental restorations differ extensively in vivo in their cytotoxic and genotoxic potential and in their ability to affect chromosomal integrity, cell-cycle progression, DNA replication and repair. PMID:25864763

  9. An update on glass fiber dental restorative composites: a systematic review.

    PubMed

    Khan, Abdul Samad; Azam, Maria Tahir; Khan, Maria; Mian, Salman Aziz; Ur Rehman, Ihtesham

    2015-02-01

    Dentistry is a much developed field in the last few decades. New techniques have changed the conventional treatment methods as applications of new dental materials give better outcomes. The current century has suddenly forced on dentistry, a new paradigm regarding expected standards for state-of-the-art patient care. Within the field of restorative dentistry, the incredible advances in dental materials research have led to the current availability of esthetic adhesive restorations. The chemistry and structure of the resins and the nature of the glass fiber reinforced systems in dental composites are reviewed in relation to their influence and properties including mechanical, physical, thermal, biocompatibility, technique sensitivity, mode and rate of failure of restorations on clinical application. It is clear that a deeper understanding of the structure of the polymeric matrix and resin-based dental composite is required. As a result of ongoing research in the area of glass fiber reinforced composites and with the development and advancement of these composites, the future prospects of resin-based composite are encouraging. PMID:25492169

  10. Low-shrinkage dental restorative composite: modeling viscoelastic behavior during setting.

    PubMed

    Dauvillier, Bibi S; Feilzer, Albert J

    2005-04-01

    Much attention has been directed toward developing dental direct restorative composites that generate less shrinkage stress during setting. The aim of this study was to explore the viscoelastic behavior of a new class of low-shrinkage dental restorative composite during setting. The setting behavior of an experimental oxirane composite has been investigated by analyzing stress-strain data with two-parametric mechanical models. Experimental data were obtained from a dynamic test method, in which the setting light-activated composite was continuously subjected to sinusoidal strain cycles. The material parameters and the model's predictive capacity were analyzed with validated modeling procedures. The light-activated oxirane composite exhibited shrinkage delay and low polymerization shrinkage strain and stresses when compared with conventional light-activated composite. Noise in the stress data restricted the predictive ability of the Maxwell model to the elastic modulus development of the composite only. Evaluation tests of their potential as restorative material are required, to examine if the biocompatibility and mechanical properties after setting of oxirane composites are acceptable for dental use. PMID:15685614

  11. Synchrotron-radiation-based X-ray micro-computed tomography reveals dental bur debris under dental composite restorations.

    PubMed

    Hedayat, Assem; Nagy, Nicole; Packota, Garnet; Monteith, Judy; Allen, Darcy; Wysokinski, Tomasz; Zhu, Ning

    2016-05-01

    Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non-biocompatible material. Non-destructive micro-computed tomography using the BioMedical Imaging & Therapy facility 05ID-2 beamline at the Canadian Light Source was pursued at 50 keV and at a pixel size of 4 µm to image dental bur fragments under a composite resin dental filling. The bur's cutting edges that produced the fragment were also chemically analyzed. The technique revealed dental bur fragments of different sizes in different locations on the floor of the prepared surface of the teeth and under the filling, which places them in direct contact with the dentinal tubules and the dentinal fluid circulating within them. Dispersive X-ray spectroscopy elemental analysis of the dental bur edges revealed that the fragments are made of tungsten carbide-cobalt, which is bio-incompatible. PMID:27140158

  12. Swept source optical coherence tomography for quantitative and qualitative assessment of dental composite restorations

    NASA Astrophysics Data System (ADS)

    Sadr, Alireza; Shimada, Yasushi; Mayoral, Juan Ricardo; Hariri, Ilnaz; Bakhsh, Turki A.; Sumi, Yasunori; Tagami, Junji

    2011-03-01

    The aim of this work was to explore the utility of swept-source optical coherence tomography (SS-OCT) for quantitative evaluation of dental composite restorations. The system (Santec, Japan) with a center wavelength of around 1300 nm and axial resolution of 12 μm was used to record data during and after placement of light-cured composites. The Fresnel phenomenon at the interfacial defects resulted in brighter areas indicating gaps as small as a few micrometers. The gap extension at the interface was quantified and compared to the observation by confocal laser scanning microscope after trimming the specimen to the same cross-section. Also, video imaging of the composite during polymerization could provide information about real-time kinetics of contraction stress and resulting gaps, distinguishing them from those gaps resulting from poor adaptation of composite to the cavity prior to polymerization. Some samples were also subjected to a high resolution microfocus X-ray computed tomography (μCT) assessment; it was found that differentiation of smaller gaps from the radiolucent bonding layer was difficult with 3D μCT. Finally, a clinical imaging example using a newly developed dental SS-OCT system with an intra-oral scanning probe (Panasonic Healthcare, Japan) is presented. SS-OCT is a unique tool for clinical assessment and laboratory research on resin-based dental restorations. Supported by GCOE at TMDU and NCGG.

  13. Investigation of the electrical properties of some dental composite restorative materials before and after laser exposure.

    PubMed

    ElKestawy, M A; Saafan, S A; Shehata, M M; Saafan, A M

    2006-10-01

    Some electrical properties, such as piezoelectricity, ac conductivity, dielectric constant and loss tangent of nine commercial types of dental composite restorative materials, have been investigated before and after laser exposure for 3s to study the effect of a probable laser exposure during some surgeries on the electrical properties of these materials. No piezoelectric effect has been found in these materials before and after laser exposure. The materials were found to be good insulators (very poorly conducting materials). The temperature and frequency dependence of ac conductivity, dielectric constant and loss tangent have not shown significant changes in values after laser exposure. PMID:16387356

  14. Dental Composite Restorations and Neuropsychological Development in Children: Treatment Level Analysis from a Randomized Clinical Trial

    PubMed Central

    Maserejian, Nancy N.; Trachtenberg, Felicia L.; Hauser, Russ; McKinlay, Sonja; Shrader, Peter; Bellinger, David C.

    2012-01-01

    Background Resin-based dental restorations may intra-orally release their components and bisphenol A. Gestational bisphenol A exposure has been associated with poorer executive functioning in children. Objectives To examine whether exposure to resin-based composite restorations is associated with neuropsychological development in children. Methods Secondary analysis of treatment level data from the New England Children’s Amalgam Trial, a 2-group randomized safety trial conducted from 1997–2006. Children (N=534) aged 6–10 y with >2 posterior tooth caries were randomized to treatment with amalgam or resin-based composites (bisphenol-A-diglycidyl-dimethacrylate-composite for permanent teeth; urethane dimethacrylate-based polyacid-modified compomer for primary teeth). Neuropsychological function at 4- and 5-year follow-up (N=444) was measured by a battery of tests of executive function, intelligence, memory, visual-spatial skills, verbal fluency, and problem-solving. Multivariable generalized linear regression models were used to examine the association between composite exposure levels and changes in neuropsychological test scores from baseline to follow-up. For comparison, data on children randomized to amalgam treatment were similarly analyzed. Results With greater exposure to either dental composite material, results were generally consistent in the direction of slightly poorer changes in tests of intelligence, achievement or memory, but there were no statistically significant associations. For the four primary measures of executive function, scores were slightly worse with greater total composite exposure, but statistically significant only for the test of Letter Fluency (10-surface-years β= −0.8, SE=0.4, P=0.035), and the subtest of color naming (β= −1.5, SE=0.5, P=0.004) in the Stroop Color-Word Interference Test. Multivariate analysis of variance confirmed that the negative associations between composite level and executive function were not

  15. Contraction behaviors of dental composite restorations--finite element investigation with DIC validation.

    PubMed

    Chuang, Shu-Fen; Chang, Chih-Han; Chen, Terry Yuan-Fang

    2011-11-01

    The objective of this study was to examine the effects of cavity configuration on the polymerization shrinkage and stress of light-cured composite restorations by combining local strain measurement and a finite element analysis (FEA). Dental mesio-occluso-distal cavities of various widths and depths (each for 2 vs. 4 mm), representing different configuration factors, were prepared on extracted molars. The displacements of the bonded tooth cusps and cavity floors, caused by polymerization shrinkage of composite restorations, were assessed utilizing a digital-image-correlation (DIC) technique. The cervical marginal microleakage was investigated by examining the resin replicas of these restorations under SEM. The local material properties of the polymerized composite along the curing depth were defined by the nanoindentation test and applied in the subsequent FEA. In the FEA, four models were generated to correspond with the experimental restorations. In the DIC measurement results, the 4(w)×4(D) mm cavity presented the greatest values of inward displacements at the cusp and floor. The cavity depth, rather than the cavity width, was found to significantly correlate to the floor deformation, the location of shrinkage centers, and also the cervical microleakage ratio. The FEA simulation results showed that the 2(w)×4(D) mm cavity presented the maximal von Mises and principal stress located respectively on the cervical margins and cavity floor. Additional safety factor analysis showed a high risk of bond failure over the cavity floor in the 4-mm deep cavity. With the experimental validation, the simulation revealed that the cavity depth was significant to the formation of contraction stress and the incidence of interfacial debonding. PMID:22098914

  16. Assessing ex vivo dental biofilms and in vivo composite restorations using cross-polarization optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Jones, R.; Aparicio, C.; Chityala, R.; Chen, R.; Fok, A.; Rudney, J.

    2012-01-01

    A cross-polarization 1310-nm optical coherence tomography system (CP-OCT), using a beam splitter based design, was used to assess ex vivo growth of complex multi-species dental biofilms. These biofilm microcosms were derived from plaque samples along the interface of composite or amalgam restoration in children with a history of early childhood caries. This paper presents a method of measuring the mean biofilm height of mature biofilms using CP-OCT. For our in vivo application, the novel swept source based CP-OCT intraoral probe (Santec Co. Komaki, Japan) dimensions and system image acquisition speed (20 image frames/second) allowed imaging pediatric subjects as young as 4 years old. The subsurface enamel under the interface of composite resin restorations of pediatric subjects were imaged using CP-OCT. Cavitated secondary caries is clearly evident from sound resin composite restorations.

  17. Non-thermal Atmospheric Plasma Treatment for Deactivation of Oral Bacteria and Improvement of Dental Composite Restoration

    NASA Astrophysics Data System (ADS)

    Yu, Qing Song; Li, H.; Ritts, A. C.; Yang, B.; Chen, M.; Hong, L.; Xu, C.; Yao, X.; Wang, Y.

    This paper reviews our recent research results of using non-thermal ­atmospheric plasmas for oral bacterial deactivation and for composite restoration improvement. Oral bacteria of Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. The plasma exposure time for a 99.9999% cell reduction was less than 15 s for S. mutans and within 5 min for L. acidophilus. To evaluate the dentin/composite interfacial bonding, extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. After dental composite application and light curing, the teeth were then sectioned into micro-bars as the specimens for microtensile test. Student Newman Keuls (SNK) tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment of the dentin surfaces. These findings indicated that non-thermal atmospheric plasma technology is very promising for dental clinical applications.

  18. Before and After (Dental Restorations)

    MedlinePlus

    FAQs | Common Questions Why see a prosthodontist? Dentures Dental Implants Board Certification Improving Your Smile Conditions & Symptoms | ... of Care in the Restoration and Replacement of Teeth This site brought to you by: American College ...

  19. Clinical cross-polarization optical coherence tomography assessment of subsurface enamel below dental resin composite restorations

    PubMed Central

    Lenton, Patricia; Rudney, Joel; Fok, Alex; Jones, Robert S.

    2014-01-01

    Abstract. A newly designed intraoral swept source cross-polarization optical coherence tomography (CP-OCT) imaging system was used to examine the integrity of the subsurface enamel below resin composite restorations placed in primary teeth. CP-OCT analysis was performed using images obtained from resin composite restoration in 62 (n=62) pediatric subjects. Clinical examination was performed by a single examiner prior to CP-OCT imaging and analysis. CP-OCT images are presented using a unique combined intensity image, where a false color scale is overlaid on the grayscale intensity image. There was a clear difference in the distribution of the mean-backscattered intensity (mR) between restorations recently placed and those possessing frank cavitation (Student’s t-test, P<0.0001). For mR above 15.49 dB, the sensitivity was 80% and specificity 86%. The Youden index J was 0.8 above 12.3 dB where sensitivity was 100% and specificity was 80%. CP-OCT imaging may be used to confirm the subsurface marginal integrity below resin composite restorations but with careful consideration of limitations of the imaging modality. CP-OCT imaging may be a useful adjunct to clinical visual investigation to confirm that a composite margin has a sound and well-adapted interface. PMID:26158031

  20. Clinical cross-polarization optical coherence tomography assessment of subsurface enamel below dental resin composite restorations.

    PubMed

    Lenton, Patricia; Rudney, Joel; Fok, Alex; Jones, Robert S

    2014-04-01

    A newly designed intraoral swept source cross-polarization optical coherence tomography (CP-OCT) imaging system was used to examine the integrity of the subsurface enamel below resin composite restorations placed in primary teeth. CP-OCT analysis was performed using images obtained from resin composite restoration in 62 ([Formula: see text]) pediatric subjects. Clinical examination was performed by a single examiner prior to CP-OCT imaging and analysis. CP-OCT images are presented using a unique combined intensity image, where a false color scale is overlaid on the grayscale intensity image. There was a clear difference in the distribution of the mean-backscattered intensity (mR) between restorations recently placed and those possessing frank cavitation (Student's t-test, [Formula: see text]). For mR above 15.49 dB, the sensitivity was 80% and specificity 86%. The Youden index J was 0.8 above 12.3 dB where sensitivity was 100% and specificity was 80%. CP-OCT imaging may be used to confirm the subsurface marginal integrity below resin composite restorations but with careful consideration of limitations of the imaging modality. CP-OCT imaging may be a useful adjunct to clinical visual investigation to confirm that a composite margin has a sound and well-adapted interface. PMID:26158031

  1. Effects of restoration and substrate on polymerization contraction stress of dental composites.

    PubMed

    Feng, L; Nunez, R; Carvalho, R; Suh, B I

    2009-02-01

    The aim of this study was to treat both restoration and substrate as a combined factor (RS-factor) to complement the popular C-factor in prediction of polymerization contraction stress (PCS). A simple model consists of a uniaxial restoration with a curing composite sandwiched between two solid mountings (substrates). By using the equal stress principle and taking into account substrate deformation, a set of equations were developed and solved, resulting in a mathematical relationship between PCS and the size and stiffness of the substrate and the restoration. The strain gage method was used to experimentally assess the PCS of a light-cured composite encircled in an aluminum ring. Differently sized inserts made of cured composites and glass were placed in the center of the ring to control the thickness of the composite to be cured and created different RS factors as well as C-factors. According to the model, a restoration with a small RS-factor will produce a high PCS. The model also predicts that a restoration with a small C-factor will have a high PCS because of the compliance of substrates. These predictions were tentatively confirmed by the strain gage measurements. A higher PCS was detected when a smaller insert was used, which created a smaller RS-factor or C-factor, or when a glass insert was used instead of a less stiff composite insert, in which the former created a smaller RS-factor. The RS-factor may be a dominant factor in determining the PCS outcome in some special cases. PMID:18561293

  2. Flexural strength of dental composite restoratives: comparison of biaxial and three-point bending test.

    PubMed

    Chung, S M; Yap, A U J; Chandra, S P; Lim, C T

    2004-11-15

    This study compared two test methods used to evaluate the flexural strength of resin-based dental composites. The two test methods evaluated were the three-point bending test4 and the biaxial flexural test. Materials used in this investigation were from the same manufacturer (3M ESPE) and included microfill (A110), minifill (Z100 and Filtek Z250), polyacid modified (F2000), and flowable [Filtek Flowable (FF)] composites. Flexural strength was determined with the use of both test methods after 1 week of conditioning in water at 37 degrees C. Data were analyzed with the use of an ANOVA/Scheffe test and an independent-samples t test at significance level 0.05. Mean flexural strength (n = 7) ranged from 66.61 to 147.21 and 67.27 to 182.81 MPa for three-point bending and ball-on-three-ball biaxial test methods, respectively. In both test methods, Z100 was significantly stronger than all other composites evaluated. In the three-point bending test, flexural strength of Z250 was significantly higher than A110, F2000 and FF, and FF was significantly stronger than A110 and F2000. The biaxial test method arrived at the same conclusions except that there was no significant difference between Z250 and FF. Pearson's correlation revealed a significantly (p < 0.01) positive and good correlation (R2 = 0.72) in flexural strength between the two test methods. Although the biaxial test has the advantage of utilizing small specimens, the low reproducibility of this test method does not support the proposition that it is a more reliable test method when compared to the ISO three-point bending test. PMID:15386492

  3. Class II Resin Composites: Restorative Options.

    PubMed

    Patel, Minesh; Mehta, Shamir B; Banerji, Subir

    2015-10-01

    Tooth-coloured, resin composite restorations are amongst the most frequently prescribed forms of dental restoration to manage defects in posterior teeth. The attainment of a desirable outcome when placing posterior resin composite restorations requires the clinician to have a good understanding of the benefits (as well as the limitations) posed by this material, together with a sound knowledge of placement technique. Numerous protocols and materials have evolved to assist the dental operator with this type of demanding posterior restoration. With the use of case examples, four techniques available are reported here. CPD/Clinical Relevance: This article explores varying techniques for the restoration of Class II cavities using resin composite. PMID:26685471

  4. Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration

    PubMed Central

    2015-01-01

    This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe3+ additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe–catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives. PMID:26176305

  5. Effect of modulated photo-activation on polymerization shrinkage behavior of dental restorative resin composites.

    PubMed

    Tauböck, Tobias T; Feilzer, Albert J; Buchalla, Wolfgang; Kleverlaan, Cornelis J; Krejci, Ivo; Attin, Thomas

    2014-08-01

    This study investigated the influence of modulated photo-activation on axial polymerization shrinkage, shrinkage force, and hardening of light- and dual-curing resin-based composites. Three light-curing resin composites (SDR bulk-fill, Esthet X flow, and Esthet X HD) and one dual-curing material (Rebilda DC) were subjected to different irradiation protocols with identical energy density (27 J cm(-2) ): high-intensity continuous light (HIC), low-intensity continuous light (LIC), soft-start (SS), and pulse-delay curing (PD). Axial shrinkage and shrinkage force of 1.5-mm-thick specimens were recorded in real time for 15 min using custom-made devices. Knoop hardness was determined at the end of the observation period. Statistical analysis revealed no significant differences among the curing protocols for both Knoop hardness and axial shrinkage, irrespective of the composite material. Pulse-delay curing generated the significantly lowest shrinkage forces within the three light-curing materials SDR bulk-fill, Esthet X flow, and Esthet X HD. High-intensity continuous light created the significantly highest shrinkage forces within Esthet X HD and Rebilda DC, and caused significantly higher forces than LIC within Esthet X flow. In conclusion, both the composite material and the applied curing protocol control shrinkage force formation. Pulse-delay curing decreases shrinkage forces compared with high-intensity continuous irradiation without affecting hardening and axial polymerization shrinkage. PMID:25039287

  6. Finite element calculation of residual stress in dental restorative material

    NASA Astrophysics Data System (ADS)

    Grassia, Luigi; D'Amore, Alberto

    2012-07-01

    A finite element methodology for residual stresses calculation in dental restorative materials is proposed. The material under concern is a multifunctional methacrylate-based composite for dental restorations, activated by visible light. Reaction kinetics, curing shrinkage, and viscoelastic relaxation functions were required as input data on a structural finite element solver. Post cure effects were considered in order to quantify the residual stresses coming out from natural contraction with respect to those debited to the chemical shrinkage. The analysis showed for a given test case that residual stresses frozen in the dental restoration at uniform temperature of 37°C are of the same order of magnitude of the strength of the dental composite material per se.

  7. Release and toxicity of dental resin composite

    PubMed Central

    Gupta, Saurabh K.; Saxena, Payal; Pant, Vandana A.; Pant, Aditya B.

    2012-01-01

    Dental resin composite that are tooth-colored materials have been considered as possible substitutes to mercury-containing silver amalgam filling. Despite the fact that dental resin composites have improved their physico-chemical properties, the concern for its intrinsic toxicity remains high. Some components of restorative composite resins are released in the oral environment initially during polymerization reaction and later due to degradation of the material. In vitro and in vivo studies have clearly identified that these components of restorative composite resins are toxic. But there is a large gap between the results published by research laboratories and clinical reports. The objective of this manuscript was to review the literature on release phenomenon as well as in vitro and in vivo toxicity of dental resin composite. Interpretation made from the recent data was also outlined. PMID:23293458

  8. Antibacterial dental restorative materials: a state-of-the-art review.

    PubMed

    Chen, Liang; Shen, Hong; Suh, Byoung In

    2012-12-01

    This review presents an updated knowledge on the antibacterial dental restorative materials and their performance clinically and in the laboratory. A search of English peer-reviewed dental literature over the last 30 years from PubMed and MEDLINE databases was conducted, and the key words included antibacterial, antimicrobial, dental, primer, adhesive, bonding agent, cement, and composite. Titles and abstracts of the articles listed from search results were reviewed and evaluated for relevancy. In summary, the incorporation of an appropriate amount of antibacterial agent provided dental restorative materials (dental bonding agents, resin composites, resin cements, glass-ionomer cements) antibacterial activity without significantly influencing mechanical properties. PMID:23409624

  9. Nonthermal Atmospheric Plasmas in Dental Restoration.

    PubMed

    Liu, Y; Liu, Q; Yu, Q S; Wang, Y

    2016-05-01

    It is well known that the service life of contemporary composite restoration is unsatisfactory, and longevity of dentin bonding is one of the major culprits. Bonding is essentially a hybridization process in which dental substrate and adhesive resin interact with each other through an exchange process. Thus, the longevity of dentin bonding can only be improved with enhanced qualities in substrate, adhesive resin, and their interaction within the hybridization zone. This review aims to collect and summarize recent advances in utilizing nonthermal atmospheric plasmas (NTAPs)-a novel technology that delivers highly reactive species in a gaseous medium at or below physiologic temperature-to improve the durability of dentin bonding by addressing these 3 issues simultaneously. Overall, NTAP has demonstrated efficacies in improving a number of critical properties for dentin bonding, including deactivation of oral pathogens, modification of surface chemistry/properties, resin polymerization, improvement in adhesive-dentin interactions, and establishment of auxiliary bonding mechanism. While a few preliminary studies have indicated the benefit of NTAP to bond strength and stability, additional researches are warranted to employ knowledge acquired so far and to evaluate these properties in a systematic way. PMID:26848068

  10. Reasons for Placement of Restorations on Previously Unrestored Tooth Surfaces by Dental PBRN Dentists

    PubMed Central

    Nascimento, Marcelle M.; Gordan, Valeria V.; Qvist, Vibeke; Litaker, Mark S.; Rindal, D. Brad; Williams, O.D.; Fellows, Jeffrey L.; Ritchie, Lloyd K.; Mjör, Ivar A.; McClelland, Jocelyn; Gilbert, Gregg H.

    2010-01-01

    Objective To identify and quantify the reasons for placing restorations on unrestored permanent tooth surfaces and the dental materials used by Dental Practice-Based Research Network (DPBRN; www.DentalPBRN.org) dentists. Methods A total of 229 DPBRN practitioner-investigators collected data on 9,890 consecutive restorations from 5,810 patients. Information included: (1) reasons for restoring; (2) tooth and surfaces restored; and (3) restorative materials employed. Results Primary caries (85%) and non-carious defects (15%), which included abrasion/ abfraction/ erosion lesions and tooth fracture, were the main reasons for placement of restorations. Restorations due to caries were frequently placed on occlusal surfaces (49%), followed by distal, mesial, buccal/facial, lingual/palatal, and incisal surfaces. Amalgam was used for 46% of the molar and 45% of the premolar restorations. Directly placed resin-based composite (RBC) was used for 48% of the molar, 49% of the premolar, and 92% of the anterior restorations. Conclusion Dental caries on occlusal and proximal surfaces of molar teeth are the main reasons for placing restorations on previously unrestored tooth surfaces by DPBRN practitioner-investigators. RBC is the material most commonly used for occlusal and anterior restorations. Amalgam remains the material of choice to restore proximal caries in posterior teeth, although there are significant differences by DPBRN region. PMID:20354094

  11. Scattering and Absorption Properties of Biomaterials for Dental Restorative Applications

    NASA Astrophysics Data System (ADS)

    Fernandez-Oliveras, A.; Rubiño, M.; Pérez, M. M.

    2013-08-01

    The physical understanding of the optical properties of dental biomaterials is mandatory for their final success in restorative applications.Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function,the refractive index, and the surface conditions (roughness). We have employed the inverse adding-doubling (IAD) method to combine transmittance and reflectance measurements performed using an integrating-sphere setup with the results of the previous scattering-anisotropygoniometric measurements. This has led to the determination of the absorption and the scattering coefficients. The aim was to optically characterize two different dental-resin composites (nanocomposite and hybrid) and one type of zirconia ceramic, and comparatively study them. The experimental procedure was conducted under repeatability conditions of measurement in order to determine the uncertainty associated to the optical properties of the biomaterials. Spectral variations of the refraction index and the scattering anisotropy factor were also considered. The whole experimental procedure fulfilled all the necessary requirements to provide optical-property values with lower associated uncertainties. The effective transport coefficient presented a similar spectral behavior for the two composites but completely different for the zirconia ceramic. The results demonstrated that the scattering anisotropy exerted a clearly distinct impact on the optical properties of the zirconia ceramic compared with those of the dental-resin composites.

  12. Longevity of Posterior Composite Restorations

    PubMed Central

    Opdam, N.J.M.; van de Sande, F.H.; Bronkhorst, E.; Cenci, M.S.; Bottenberg, P.; Pallesen, U.; Gaengler, P.; Lindberg, A.; Huysmans, M.C.D.N.J.M.; van Dijken, J.W.

    2014-01-01

    The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years’ follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces. PMID:25048250

  13. Radiographic diagnosis of dental restoration misfit: a systematic review.

    PubMed

    Liedke, G S; Spin-Neto, R; da Silveira, H E D; Wenzel, A

    2014-12-01

    The objective of this study was to perform a systematic review on the use of radiographic methods for the diagnosis of misfit in dental prostheses and restorations. The MEDLINE bibliographic database was searched from 1950 to February 2014 for reports on the radiographic diagnosis of misfits. The search strategy was limited to English-language publications using the following combined MeSH terms in the search strategy: (Dental Restoration OR Dental Prosthesis OR Crown OR Inlays OR Dental Abutments) and (Dental Leakage OR Prosthesis Fitting OR Dental Marginal Adaptation OR Surface Properties) and (Radiography, Dental OR Radiography, Dental, Digital OR Cone-Beam Computed Tomography). Twenty-eight publications were identified and read in full text, and 14 studies fulfilled criteria for inclusion. Information regarding the use of radiographic methods for the diagnosis of misfits in dental prosthesis and restorations, and in which the methodology/results comprised information regarding how the sample was collected/prepared, the method, imaging protocol, presence of a reference test and the outcomes were evaluated. QUADAS criteria was used to rate the studies in high, moderate or low quality. The evidence supporting the use of radiographic methods for the diagnosis of misfits in dental prosthesis and restorations is limited to low-/moderate-quality studies. The well-established intra-oral orthogonal projection is still under investigation and considered the most appropriate method, both when evaluating the relation between dental restoration to tooth and abutment to implant. Studies using digital radiographs have not evaluated the effect of image post-processing, and tomography has not been evaluated. PMID:25142004

  14. Clinical Investigation of a New Bulk Fill Composite Resin in the Restoration of Posterior Teeth

    ClinicalTrials.gov

    2016-09-07

    Dental Restoration Failure of Marginal Integrity; Dental Caries; Unrepairable Overhanging of Dental Restorative Materials; Poor Aesthetics of Existing Restoration; Secondary Dental Caries Associated With Failed or Defective Dental Restorations; Fractured Dental Restorative Materials Without Loss of Materials; Fracture of Dental Restorative Materials With Loss of Material

  15. Loss of Alloy in Cast Restorations Fabricated by Dental Students.

    ERIC Educational Resources Information Center

    Soh, George

    1991-01-01

    A study investigated the quantity of alloy lost in the fabrication of three types of cast restoration by dental students, and identified the proportion of loss at each of the four principal stages of the fabrication process. Suggestions for reducing metal loss and related costs in dental schools are offered. (MSE)

  16. New nano-sized Al2O3-BN coating 3Y-TZP ceramic composites for CAD/CAM-produced all-ceramic dental restorations. Part I. Fabrication of powders.

    PubMed

    Yang, Se Fei; Yang, Li Qiang; Jin, Zhi Hao; Guo, Tian Wen; Wang, Lei; Liu, Hong Chen

    2009-06-01

    Partially sintered 3 mol % yttria-stabilized tetragonal zirconium dioxide (ZrO(2), zirconia) polycrystal (3Y-TZP) ceramics are used in dental posterior restorations with computer-aided design-computer-aided manufacturing (CAD/CAM) techniques. High strength is acquired after sintering, but shape distortion of preshaped compacts during their sintering is inevitable. The aim of this study is to fabricate new machinable ceramic composites with strong mechanical properties that are fit for all-ceramic dental restorations. Aluminum oxide (Al(2)O(3))-coated 3Y-TZP powders were first prepared by the heterogeneous precipitation method starting with 3Y-TZP, Al(NO(3))(3) . 9H(2)O, and ammonia, then amorphous boron nitride (BN) was produced and the as-received composite powders were coated via in situ reaction with boric acid and urea. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to analyze the status of Al(2)O(3)-BN on the surface of the 3Y-TZP particles. TEM micrographs show an abundance of Al(2)O(3) particles and amorphous BN appearing uniformly on the surface of the 3Y-TZP particles after the coating process. The size of the Al(2)O(3) particles is about 20 nm. The XRD pattern shows clearly the peak of amorphous BN among the peaks of ZrO(2). PMID:19223246

  17. The demand for preventive and restorative dental services.

    PubMed

    Meyerhoefer, Chad D; Zuvekas, Samuel H; Manski, Richard

    2014-01-01

    Chronic tooth decay is the most common chronic condition in the United States among children ages 5-17 and also affects a large percentage of adults. Oral health conditions are preventable, but less than half of the US population uses dental services annually. We seek to examine the extent to which limited dental coverage and high out-of-pocket costs reduce dental service use by the nonelderly privately insured and uninsured. Using data from the 2001-2006 Medical Expenditure Panel Survey and an American Dental Association survey of dental procedure prices, we jointly estimate the probability of using preventive and both basic and major restorative services through a correlated random effects specification that controls for endogeneity. We found that dental coverage increased the probability of preventive care use by 19% and the use of restorative services 11% to 16%. Both conditional and unconditional on dental coverage, the use of dental services was not sensitive to out-of-pocket costs. We conclude that dental coverage is an important determinant of preventive dental service use, but other nonprice factors related to consumer preferences, especially education, are equal if not stronger determinants. PMID:23349123

  18. Nanotechnology-based restorative materials for dental caries management

    PubMed Central

    Melo, Mary A.S.; Guedes, Sarah F.F.; Xu, Hockin H.K.; Rodrigues, Lidiany K.A.

    2013-01-01

    Nanotechnology has been applied to dental materials as an innovative concept for the development of materials with better properties and anticaries potential. In this review we discuss the current progress and future applications of functional nanoparticles incorporated in dental restorative materials as useful strategies to dental caries management. We also overview proposed antimicrobial and remineralizing mechanisms. Nanomaterials have great potential to decrease biofilm accumulation, inhibit the demineralization process, to be used for remineralizing tooth structure, and to combat caries-related bacteria. These results are encouraging and open the doors to future clinical studies that will allow the therapeutic value of nanotechnology-based restorative materials to be established. PMID:23810638

  19. Complex layered dental restorations: Are they recognizable and do they survive extreme conditions?

    PubMed

    Soon, Alistair S; Bush, Mary A; Bush, Peter J

    2015-09-01

    Recent research has shown that restorative dental materials can be recognized by microscopy and elemental analysis (scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence; SEM/EDS and XRF) and that this is possible even in extreme conditions, such as cremation. These analytical methods and databases of dental materials properties have proven useful in DVI (disaster victim identification) of a commercial plane crash in 2009, and in a number of other victim identification cases. Dental materials appear on the market with ever expanding frequency. With their advent, newer methods of restoration have been proposed and adopted in the dental office. Methods might include placing multiple layers of dental materials, where they have different properties including adhesion, viscosity, or working time. These different dental materials include filled adhesives, flowable resins, glass ionomer cements, composite resins, liners and sealants. With possible combinations of different materials in these restorations, the forensic odontologist is now confronted with a new difficulty; how to recognize each individual material. The question might be posed if it is even possible to perform this task. Furthermore, an odontologist might be called upon to identify a victim under difficult circumstances, such as when presented with fragmented or incinerated remains. In these circumstances the ability to identify specific dental materials could assist in the identification of the deceased. Key to use of this information is whether these new materials and methods are detailed in the dental chart. Visual or radiographic inspection may not reveal the presence of a restoration, let alone the possible complex nature of that restoration. This study demonstrates another scientific method in forensic dental identification. PMID:26151675

  20. Recommendations for conducting controlled clinical studies of dental restorative materials.

    PubMed

    Hickel, R; Roulet, J-F; Bayne, S; Heintze, S D; Mjör, I A; Peters, M; Rousson, V; Randall, R; Schmalz, G; Tyas, M; Vanherle, G

    2007-03-01

    About 35 years ago, Ryge provided a practical approach to evaluation of clinical performance of restorative materials. This systematic approach was soon universally accepted. While that methodology has served us well, a large number of scientific methodologies and more detailed questions have arisen that require more rigor. Current restorative materials have vastly improved clinical performance and any changes over time are not easily detected by the limited sensitivity of the Ryge criteria in short term clinical investigations. However, the clinical evaluation of restorations not only involves the restorative material per se but also different operative techniques. For instance, a composite resin may show good longevity data when applied in conventional cavities but not in modified operative approaches. Insensitivity, combined with the continually evolving and non-standard investigator modifications of the categories, scales, and reporting methods, has created a body of literature that is extremely difficult to meaningfully interpret. In many cases, the insensitivity of the original Ryge methods is misinterpreted as good clinical performance. While there are many good features of the original system, it is now time to move to a more contemporary one. The current review approaches this challenge in two ways: (1) a proposal for a modern clinical testing protocol for controlled clinical trials, and (2) an in-depth discussion of relevant clinical evaluation parameters, providing 84 references that are primarily related to issues or problems for clinical research trials. Together, these two parts offer a standard for the clinical testing of restorative materials/procedures and provide significant guidance for research teams in the design and conduct of contemporary clinical trials. Part 1 of the review considers the recruitment of subjects, restorations per subject, clinical events, validity versus bias, legal and regulatory aspects, rationales for clinical trial

  1. In situ reaction kinetic analysis of dental restorative materials

    NASA Astrophysics Data System (ADS)

    Younas, Basma; Samad Khan, Abdul; Muzaffar, Danish; Hussain, Ijaz; Chaudhry, Aqif Anwar; Rehman, Ihtesham Ur

    2013-12-01

    The objective of this study was to evaluate in situ structural and thermal changes of dental restorative materials at periodical time intervals. The commercial materials included zinc oxide eugenol (ZOE), zinc phosphate type I (ZnPO4), glass ionomer cement type II (GIC) and resin-based nano-omposite (Filtek Z350 XT). These materials were processed according to manufacturer's instructions. For the structural analysis Fourier transform infrared spectroscopy (FTIR) was used at high resolution. TGA was used to evaluate thermal weight-loss. The FTIR spectra were collected at periodic time intervals. FTIR spectra showed that with time passing all materials exhibited an increase in peak intensities and a new appearance of shoulders and shifting of peaks for example, ZnPO4 (P-O), ZOE (C═O, C═N, C-O-C), GIC (COO-, C-H, Si-OH), composites (C═O, C═C, C═N, C-N-H). The peaks were replaced by bands and these bands became broader with time interval. Composites showed a degree of conversion and new peaks corresponded to the cross-linking of polymer composites. TGA analysis showed that significant changes in weight loss of set materials were observed after 24 h, where ZOE showed continuous changes in thermal degradation. The spectral changes and thermal degradation with time interval elucidated in situ setting behaviour and understanding of their bonding compatibility with tooth structure and change in relation to time.

  2. Understanding dental CAD/CAM for restorations - dental milling machines from a mechanical engineering viewpoint.

    PubMed

    Lebon, Nicolas; Tapie, Laurent; Duret, Francois; Attal, Jean-Pierre

    2016-01-01

    Nowadays, dental numerical controlled (NC) milling machines are available for dental laboratories (labside solution) and dental production centers. This article provides a mechanical engineering approach to NC milling machines to help dental technicians understand the involvement of technology in digital dentistry practice. The technical and economic criteria are described for four labside and two production center dental NC milling machines available on the market. The technical criteria are focused on the capacities of the embedded technologies of milling machines to mill prosthetic materials and various restoration shapes. The economic criteria are focused on investment cost and interoperability with third-party software. The clinical relevance of the technology is discussed through the accuracy and integrity of the restoration. It can be asserted that dental production center milling machines offer a wider range of materials and types of restoration shapes than labside solutions, while labside solutions offer a wider range than chairside solutions. The accuracy and integrity of restorations may be improved as a function of the embedded technologies provided. However, the more complex the technical solutions available, the more skilled the user must be. Investment cost and interoperability with third-party software increase according to the quality of the embedded technologies implemented. Each private dental practice may decide which fabrication option to use depending on the scope of the practice. PMID:27274561

  3. Ceramic whisker reinforcement of dental resin composites.

    PubMed

    Xu, H H; Martin, T A; Antonucci, J M; Eichmiller, F C

    1999-02-01

    Resin composites currently available are not suitable for use as large stress-bearing posterior restorations involving cusps due to their tendencies toward excessive fracture and wear. The glass fillers in composites provide only limited reinforcement because of the brittleness and low strength of glass. The aim of the present study was to reinforce dental resins with ceramic single-crystalline whiskers of elongated shapes that possess extremely high strength. A novel method was developed that consisted of fusing silicate glass particles onto the surfaces of individual whiskers for a two-fold benefit: (1) to facilitate silanization regardless of whisker composition; and (2) to enhance whisker retention in the matrix by providing rougher whisker surfaces. Silicon nitride whiskers, with an average diameter of 0.4 microm and length of 5 microm, were coated by the fusion of silica particles 0.04 microm in size to the whisker surface at temperatures ranging from 650 degrees C to 1000 degrees C. The coated whiskers were silanized and manually blended with resins by spatulation. Flexural, fracture toughness, and indentation tests were carried out for evaluation of the properties of the whisker-reinforced composites in comparison with conventional composites. A two-fold increase in strength and toughness was achieved in the whisker-reinforced composite, together with a substantially enhanced resistance to contact damage and microcracking. The highest flexural strength (195+/-8 MPa) and fracture toughness (2.1+/-0.3 MPa x m(1/2)) occurred in a composite reinforced with a whisker-silica mixture at whisker:silica mass ratio of 2:1 fused at 800 degrees C. To conclude, the strength, toughness, and contact damage resistance of dental resin composites can be substantially improved by reinforcement with fillers of ceramic whiskers fused with silica glass particles. PMID:10029470

  4. Various Effects of Sandblasting of Dental Restorative Materials

    PubMed Central

    Nishigawa, Goro; Maruo, Yukinori; Irie, Masao; Maeda, Naoto; Yoshihara, Kumiko; Nagaoka, Noriyuki; Matsumoto, Takuya; Minagi, Shogo

    2016-01-01

    Background Sandblasting particles which remain on the surfaces of dental restorations are removed prior to cementation. It is probable that adhesive strength between luting material and sandblasting particle remnants might exceed that with restorative material. If that being the case, blasting particles adhere to sandblasted material surface could be instrumental to increasing adhesive strength like underlying bonding mechanism between luting material and silanized particles of tribochemical silica coating-treated surface. We hypothesize that ultrasonic cleaning of bonding surfaces, which were pretreated with sandblasting, may affect adhesive strength of a resin luting material to dental restorative materials. Methods We therefore observed adhesive strength of resin luting material to aluminum oxide was greater than those to zirconia ceramic and cobalt-chromium alloy beforehand. To measure the shear bond strengths of resin luting material to zirconia ceramic and cobalt-chromium alloy, forty specimens of each restorative material were prepared. Bonding surfaces were polished with silicon abrasive paper and then treated with sandblasting. For each restorative material, 40 sandblasted specimens were equally divided into two groups: ultrasonic cleaning (USC) group and non-ultrasonic cleaning (NUSC) group. After resin luting material was polymerized on bonding surface, shear test was performed to evaluate effect of ultrasonic cleaning of bonding surfaces pretreated with sandblasting on bond strength. Results For both zirconia ceramic and cobalt-chromium alloy, NUSC group showed significantly higher shear bond strength than USC group. Conclusions Ultrasonic cleaning of dental restorations after sandblasting should be avoided to retain improved bonding between these materials. PMID:26764913

  5. Effect of Industry Sponsorship on Dental Restorative Trials.

    PubMed

    Schwendicke, F; Tu, Y-K; Blunck, U; Paris, S; Göstemeyer, G

    2016-01-01

    Industry sponsorship was found to potentially introduce bias into clinical trials. We assessed the effects of industry sponsorship on the design, comparator choice, and findings of randomized controlled trials on dental restorative materials. A systematic review was performed via MEDLINE, CENTRAL, and EMBASE. Randomized trials on dental restorative and adhesive materials published 2005 to 2015 were included. The design of sponsored and nonsponsored trials was compared statistically (risk of bias, treatment indication, setting, transferability, sample size). Comparator choice and network geometry of sponsored and nonsponsored trials were assessed via network analysis. Material performance rankings in different trial types were estimated via Bayesian network meta-analysis. Overall, 114 studies were included (15,321 restorations in 5,232 patients). We found 21 and 41 (18% and 36%) trials being clearly or possibly industry sponsored, respectively. Trial design of sponsored and nonsponsored trials did not significantly differ for most assessed items. Sponsored trials evaluated restorations of load-bearing cavities significantly more often than nonsponsored trials, had longer follow-up periods, and showed significantly increased risk of detection bias. Regardless of sponsorship status, comparisons were mainly performed within material classes. The proportion of trials comparing against gold standard restorative or adhesive materials did not differ between trial types. If ranked for performance according to the need to re-treat (best: least re-treatments), most material combinations were ranked similarly in sponsored and nonsponsored trials. The effect of industry sponsorship on dental restorative trials seems limited. PMID:26442947

  6. Long-term deterioration of composite resin and amalgam restorations.

    PubMed

    Smales, R J

    1991-01-01

    Previous long-term longitudinal studies of two different methods of placing an auto-cured conventional anterior composite resin, and of a low- and a high-copper amalgam alloy, had shown similar restoration survivals despite the different resin treatment methods used or the types of amalgam alloy placed. Therefore, the aim of the present study was to assess several clinical factors or characteristics of these restorations that were believed to affect the survival of the restorative materials. The 950 composite resin and the 1042 amalgam restorations examined were placed by many operators in numerous patients attending a dental hospital. The composite resin restorations were placed using unetched- and etched-enamel-bonding treatment methods, and the amalgam restorations were polished after insertion. Clinical ratings supplemented by color transparencies were used for the assessment of four factors for the resin, and four factors for the amalgam restoration. Significant deterioration differences were found for several of the clinical factors assessed for both the two different composite resin treatment methods, and for the two different amalgam alloys, which were not directly related to the restoration survivals. PMID:1840079

  7. Compressive fatigue limit of four types of dental restorative materials.

    PubMed

    Chen, Song; Öhman, Caroline; Jefferies, Steven R; Gray, Holly; Xia, Wei; Engqvist, Håkan

    2016-08-01

    The purpose of this study was to evaluate the quasi-static compressive strength and the compressive fatigue limit of four different dental restorative materials, before and after aging in distilled water for 30 days. A conventional glass ionomer cement (Fuji IX GP; IG), a zinc-reinforced glass ionomer cement (Chemfil rock; CF), a light curable resin-reinforced glass ionomer cement (Fuji II LC; LC) and a resin-based composite (Quixfil; QF) were investigated. Cylindrical specimens (4mm in diameter and 6mm in height) were prepared according to the manufacturer׳s instructions. The compressive fatigue limit was obtained using the staircase method. Samples were tested in distilled water at 37°C, at a frequency of 10Hz with 10(5) cycles set as run-out. 17 fatigue samples were tested for each group. Two-way ANOVA and one-way ANOVA followed by Tukey׳s post-hoc test were used to analyze the results. Among the four types of materials, the resin-based composite exhibited the highest compressive strength (244±13.0MPa) and compressive fatigue limit (134±7.8MPa), followed by the light-cured resin reinforced glass ionomer cement (168±8.5MPa and 92±6.6MPa, respectively) after one day of storage in distilled water. After being stored for 30 days, all specimens showed an increase in compressive strength. Aging showed no effect on the compressive fatigue limit of the resin-based composite and the light-cured resin reinforced glass ionomer cement, however, the conventional glass ionomer cements showed a drastic decrease (37% for IG, 31% for CF) in compressive fatigue limit. In conclusion, in the present study, resin modified GIC and resin-based composite were found to have superior mechanical properties to conventional GIC. PMID:27085845

  8. Utilizing optical coherence tomography for CAD/CAM of indirect dental restorations

    NASA Astrophysics Data System (ADS)

    Chityala, Ravishankar; Vidal, Carola; Jones, Robert

    Optical Coherence Tomography (OCT) has seen broad application in dentistry including early carious lesion detection and imaging defects in resin composite restorations. This study investigates expanding the clinical usefulness by investigating methods to use OCT for obtaining three-dimensional (3D) digital impressions, which can be integrated to CAD/CAM manufacturing of indirect restorations. 3D surface topography `before' and `after' a cavity preparation was acquired by an intraoral cross polarization swept source OCT (CP-OCT) system with a Micro-Electro-Mechanical System (MEMS) scanning mirror. Image registration and segmentation methods were used to digitally construct a replacement restoration that modeled the original surface morphology of a hydroxyapatite sample. After high resolution additive manufacturing (e.g. polymer 3D printing) of the replacement restoration, micro-CT imaging was performed to examine the marginal adaptation. This study establishes the protocol for further investigation of integrating OCT with CAD/CAM of indirect dental restorations.

  9. Resin-composite blocks for dental CAD/CAM applications.

    PubMed

    Ruse, N D; Sadoun, M J

    2014-12-01

    Advances in digital impression technology and manufacturing processes have led to a dramatic paradigm shift in dentistry and to the widespread use of computer-aided design/computer-aided manufacturing (CAD/CAM) in the fabrication of indirect dental restorations. Research and development in materials suitable for CAD/CAM applications are currently the most active field in dental materials. Two classes of materials are used in the production of CAD/CAM restorations: glass-ceramics/ceramics and resin composites. While glass-ceramics/ceramics have overall superior mechanical and esthetic properties, resin-composite materials may offer significant advantages related to their machinability and intra-oral reparability. This review summarizes recent developments in resin-composite materials for CAD/CAM applications, focusing on both commercial and experimental materials. PMID:25344335

  10. Resin-composite Blocks for Dental CAD/CAM Applications

    PubMed Central

    Ruse, N.D.; Sadoun, M.J.

    2014-01-01

    Advances in digital impression technology and manufacturing processes have led to a dramatic paradigm shift in dentistry and to the widespread use of computer-aided design/computer-aided manufacturing (CAD/CAM) in the fabrication of indirect dental restorations. Research and development in materials suitable for CAD/CAM applications are currently the most active field in dental materials. Two classes of materials are used in the production of CAD/CAM restorations: glass-ceramics/ceramics and resin composites. While glass-ceramics/ceramics have overall superior mechanical and esthetic properties, resin-composite materials may offer significant advantages related to their machinability and intra-oral reparability. This review summarizes recent developments in resin-composite materials for CAD/CAM applications, focusing on both commercial and experimental materials. PMID:25344335

  11. Backscattering from dental restorations and splint materials during therapeutic radiation

    SciTech Connect

    Farman, A.G.; Sharma, S.; George, D.I.; Wilson, D.; Dodd, D.; Figa, R.; Haskell, B.

    1985-08-01

    Models were constructed to simulate as closely as possible the human oral cavity. Radiation absorbed doses were determined for controls and various test situations involving the presence of dental restorative and splint materials during cobalt-60 irradiation of the models. Adjacent gold full crowns and adjacent solid dental silver amalgam cores both increased the dose to the interproximal gingivae by 20%. Use of orthodontic full bands for splinting the jaws increased the dose to the buccal tissues by an average of 10%. Augmentation of dose through backscatter radiation was determined to be only slight for intracoronal amalgam fillings and stainless steel or plastic bracket splints.

  12. Antibacterial Dental Composites with Chlorhexidine and Mesoporous Silica

    PubMed Central

    Zhang, J.F.; Wu, R.; Fan, Y.; Liao, S.; Wang, Y.; Wen, Z.T.; Xu, X.

    2014-01-01

    One of the leading causes for the failure of dental composite restorations is secondary caries. Effectively inhibiting cariogenic biofilms and reducing secondary caries could extend the service life of composite restorations. Dental composites releasing antibacterial agents such as chlorhexidine (CHX) have shown biofilm-inhibitory efficacy, but they usually have poor physical and mechanical properties. Herein, we present a study of a new method to encapsulate and release CHX from dental composite using mesoporous silica nanoparticles (MSNs). SBA-15 MSNs were synthesized according to a reported procedure. CHX (62.9 wt%) was encapsulated into dried MSN from 0.3 M CHX ethanol solution. The dental composites containing 0% (control), 3%, 5%, and 6.3% CHX or the same amounts of CHX entrapped in MSN (denoted as CHX@MSN) were fabricated with methacrylate monomers and silanized glass fillers (CHX or CHX@MSN + glass filler particle = 70 wt%). The monomer mixture consisted of bisphenol A glycidyl methacrylate (BisGMA), hexanediol dimethacrylate (HDDMA), ethoxylated bisphenol A dimethacrylate (EBPADMA), and urethane dimethacrylates (UEDMA) at a weight ratio of 40:30:20:10. The composites were tested for CHX release and recharge, flexural strength and modulus (at 24 hr and 1 mo), surface roughness, in vitro wear, and antibacterial activity against Streptococcus mutans and Lactobacillus casei (in both planktonic growth and biofilm formation). The results showed that the composites with CHX@MSN largely retained mechanical properties and smooth surfaces and showed controlled release of CHX over a long time. In contrast, the composites with directly mixed CHX showed reduced mechanical properties, rough surfaces, and burst release of CHX in a short time. The composites with CHX either directly mixed or in MSN showed strong inhibition to S. mutans and L. casei. This research has demonstrated the successful application of MSNs as a novel nanotechnology in dental materials to inhibit

  13. Antibacterial dental composites with chlorhexidine and mesoporous silica.

    PubMed

    Zhang, J F; Wu, R; Fan, Y; Liao, S; Wang, Y; Wen, Z T; Xu, X

    2014-12-01

    One of the leading causes for the failure of dental composite restorations is secondary caries. Effectively inhibiting cariogenic biofilms and reducing secondary caries could extend the service life of composite restorations. Dental composites releasing antibacterial agents such as chlorhexidine (CHX) have shown biofilm-inhibitory efficacy, but they usually have poor physical and mechanical properties. Herein, we present a study of a new method to encapsulate and release CHX from dental composite using mesoporous silica nanoparticles (MSNs). SBA-15 MSNs were synthesized according to a reported procedure. CHX (62.9 wt%) was encapsulated into dried MSN from 0.3 M CHX ethanol solution. The dental composites containing 0% (control), 3%, 5%, and 6.3% CHX or the same amounts of CHX entrapped in MSN (denoted as CHX@MSN) were fabricated with methacrylate monomers and silanized glass fillers (CHX or CHX@MSN + glass filler particle = 70 wt%). The monomer mixture consisted of bisphenol A glycidyl methacrylate (BisGMA), hexanediol dimethacrylate (HDDMA), ethoxylated bisphenol A dimethacrylate (EBPADMA), and urethane dimethacrylates (UEDMA) at a weight ratio of 40:30:20:10. The composites were tested for CHX release and recharge, flexural strength and modulus (at 24 hr and 1 mo), surface roughness, in vitro wear, and antibacterial activity against Streptococcus mutans and Lactobacillus casei (in both planktonic growth and biofilm formation). The results showed that the composites with CHX@MSN largely retained mechanical properties and smooth surfaces and showed controlled release of CHX over a long time. In contrast, the composites with directly mixed CHX showed reduced mechanical properties, rough surfaces, and burst release of CHX in a short time. The composites with CHX either directly mixed or in MSN showed strong inhibition to S. mutans and L. casei. This research has demonstrated the successful application of MSNs as a novel nanotechnology in dental materials to inhibit

  14. Longevity of posterior dental restorations and reasons for failure.

    PubMed

    Kopperud, Simen E; Tveit, Anne Bjørg; Gaarden, Torunn; Sandvik, Leiv; Espelid, Ivar

    2012-12-01

    Tooth-coloured restorative materials are being used increasingly more often in Class II preparations in permanent teeth. Using a practice-based study design, we aimed to assess the survival time of Class II restorations and to identify factors relevant to their longevity. Class II restorations (n = 4,030), consisting of resin composites (81.5%), compomers (12.7%), amalgams (4.6%), and glass-ionomer cement restorations (1.2%), were placed in 1,873 patients with a median age of 15 yr. In total, 92.7% of restorations were placed due to primary caries and 5.8% were replacements. After an average follow-up period of 4.6 yr, 61.6% of the restorations were successful, 11.2% had failed, and 27.2% were not available for evaluation (owing to patient drop-out). The mean annual failure rate was 2.9% for resin-composite restorations and 1.6% for amalgams. For resin-composite restorations, secondary caries was the most common reason for replacement (73.9%), followed by loss (8.0%), fracture (5.3%), and marginal defects (2.4%). Multilevel Cox-regression analyses identified young age of the patient, high previous caries experience, deep cavities, and saucer-shaped preparation technique as predisposing to shorter longevity of resin-composite restorations. One brand of resin composite had a shorter survival time than the others. PMID:23167471

  15. Dental repair material: a resin-modified glass-ionomer bioactive ionic resin-based composite.

    PubMed

    Croll, Theodore P; Berg, Joel H; Donly, Kevin J

    2015-01-01

    This report documents treatment and repair of three carious teeth that were restored with a new dental repair material that features the characteristics of both resin-modified glass-ionomer restorative cement (RMGI) and resin-based composite (RBC). The restorative products presented are reported by the manufacturer to be the first bioactive dental materials with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the physical and chemical properties of natural teeth. The restorative material and base/liner, which feature three hardening mechanisms, could prove to be a notable advancement in the adhesive dentistry restorative materials continuum. PMID:25822408

  16. Approaching biomimetics in dental restorations via photonics.

    PubMed

    Kishen, A; Asundi, A

    2002-01-01

    It is established that a natural system balances functional requirements with the anatomical optimizations it has achieved. Though such process of functional adaptation is recognized in bone tissue, any mode of functional adaptation in dental tissue is yet to be understood. In this study a three-dimensional digital photoelasticity is conducted to evaluate the nature of stress distribution in the sagittal aspect and the cross-sections of the dentine structure. Later, a fluoroscopic X-ray microscopic analysis and a microindentation experiments, are performed on different sections obtained from the sagittal and cross-sections of the dentine. These experiments aided in correlating the multi-plane pattern of mineralization and the spatial gradients in elastic modulus in the original dentine structure with the three-dimensional stress distribution in photoelastic models. This study highlights dentine structure as a biologically graded structure to functional loads. PMID:22388045

  17. Effects of high temperature on different restorations in forensic identification: Dental samples and mandible

    PubMed Central

    Patidar, Kalpana A; Parwani, Rajkumar; Wanjari, Sangeeta

    2010-01-01

    Introduction: The forensic odontologist strives to utilize the charred human dentition throughout each stage of dental evaluation, and restorations are as unique as fingerprints and their radiographic morphology as well as the types of filling materials are often the main feature for identification. The knowledge of detecting residual restorative material and composition of unrecovered adjacent restoration is a valuable tool-mark in the presumptive identification of the dentition of a burned victim. Gold, silver amalgam, silicate restoration, and so on, have a different resistance to prolonged high temperature, therefore, the identification of burned bodies can be correlated with adequate qualities and quantities of the traces. Most of the dental examination relies heavily on the presence of the restoration as well as the relationship of one dental structure to another. This greatly narrows the research for the final identification that is based on postmortem data. Aim: The purpose of this study is to examine the resistance of teeth and different restorative materials, and the mandible, to variable temperature and duration, for the purpose of identification. Materials and Methods: The study was conducted on 72 extracted teeth which were divided into six goups of 12 teeth each based on the type of restorative material. (Group 1 - unrestored teeth, group 2 - teeth restored with Zn3(PO4)2, group 3 - with silver amalgam, group 4 with glass ionomer cement, group 5 - Ni-Cr-metal crown, group 6 - metal ceramic crown) and two specimens of the mandible. The effect of incineration at 400°C (5 mins, 15 mins, 30 mins) and 1100°C (15 mins) was studied. Results: Damage to the teeth subjected to variable temperatures and time can be categorized as intact (no damage), scorched (superficially parched and discolored), charred (reduced to carbon by incomplete combustion) and incinerated (burned to ashes). PMID:21189989

  18. Monitoring Wear On Dental Restoration Surfaces Using Microscope Photogrammetry

    NASA Astrophysics Data System (ADS)

    Mitchell, Harvey L.; Chadwick, R. G.; McCabe, John F.

    1989-04-01

    35mm photography of denture teeth and resin replicas through a convergent-axes microscope was used in an assessment of wear in dental restoration materials. The difficulty was to isolate and evaluate the significant photogrammetric parameters, but thereafter, the required depths could be calculated to accuracies of 0.01 mm r.m.s. using stereocomparator observations and quite simple formulae. The technique is applicable to biomedical laboratories which have access to an appropriate microscope if photogrammetric observations can be undertaken.

  19. Factors affecting the placement or replacement of direct restorations in a dental school

    PubMed Central

    Silvani, Samara; Trivelato, Roberta Ferreira; Nogueira, Ruchele Dias; Gonçalves, Luciano de Souza; Geraldo-Martins, Vinícius Rangel

    2014-01-01

    Context: The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future. Purpose: The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University – Brazil. Materials and Methods: This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05). Results: The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1st-time placements, while 39.55% were replacements. For 1st-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05). Conclusions: The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite. PMID:24808696

  20. Effect of composite/amalgam thickness on fracture resistance of maxillary premolar teeth, restored with combined amalgam-composite restorations

    PubMed Central

    Firouzmandi, Maryam; Doozandeh, Maryam; Abbasi, Sanaz

    2016-01-01

    Background Combined amalgam-composite restorations have been used through many years to benefit from the advantages of both dental amalgam and composite resin. Two variations have been mentioned for this technique, this study investigated the fracture resistance of maxillary premolar teeth with extended mesio-occluso-distal (MOD) cavities, restored with the two variations of combined amalgam-composite restorations. Material and Methods Sixty intact extracted premolar teeth were randomly divided into 6 groups (G1-G6) of 10 teeth. G1; consisted of intact teeth and G2; consisted of teeth with MOD preparations were assigned as the positive and negative control groups respectively. Other experimental groups after MOD preparations were as follows: G3, amalgam restoration; G4, composite restoration; G5 combined amalgam-composite restoration with amalgam placement only on 1mm of the gingival floor of the proximal boxes; G6, combined amalgam-composite restoration with amalgam placement to the height of contact area of the proximal surface of the tooth. Fracture strength of the specimens was measured and the data were analyzed using one-way analysis of variance (ANOVA). The level of significance was P<0.05. Fracture mode of the specimens was also recorded. Results G1 had the highest value of fracture resistance (1736.90 N). G2 and G3 had the lowest fracture resistance (775.70 N and 874.70 N, respectively). The difference between G 4, 5 and 6 was not statistically significant. However, G4, G5 and G6 showed significantly higher resistance to fracture compared to G2 and G3. Fracture modes were favorable in all of the study groups except in G6. Conclusions Fracture resistance of the premolars restored with the two variations of combined amalgam-composite restoration was similar to that achieved with composite restoration alone and more than that of amalgam restoration alone. It can be concluded that the thickness of amalgam in combined amalgam-composite restorations did not

  1. Seventeen Years of Using Flowable Resin Restoratives--A Dental Practitioner's Personal Clinical Review.

    PubMed

    Firla, Markus Th

    2015-04-01

    Seen through the author's eyes on the basis of his practising dentistry for almost three decades, light-activated flowable resin restoratives (FRCs) or, in common clinical dental terminology, flowable composites have gradually gained major importance in restorative dentistry. Inputs to this ongoing trend are coming from continuous improvements in material properties and the favourable handling characteristics experienced with this particular group of restoratives. Intended to be used in direct adhesive filling procedures, the number and variety of recent generations of flowable composites for lining, restoration of all cavity classes (I-V), core build-ups and, more recently, 'bulk-fill-restorations', however, necessitates a profound clinical understanding of the selective use of flowable composites to ensure clinical success and guarantee long-term high quality results. Clinical relevance: Today's flowable composites allow for reliable restoration of all kinds of defects. However, both the handling characteristics and the material properties of FRCs must be fully understood before taking advantage of their potentially excellent clinical performance. PMID:26076545

  2. Testing adhesion of direct restoratives to dental hard tissue - a review.

    PubMed

    Salz, Ulrich; Bock, Thorsten

    2010-10-01

    This articles concerns itself with the testing of adhesion between direct restoratives and dental hard tissue, ie, enamel and dentin. The aim is to survey available methods for adhesion testing and influential parameters affecting experimental outcome. The testing of adhesion to indirect restorative materials, eg, ceramics and metals, is beyond the scope of this article and shall be discussed elsewhere. The longevity and success of modern dental restorations very often relies on potent dental adhesives to provide durable bonds between the dental hard substance and the restorative composite. To predict the clinical outcome of such restorative treatment, a large variety of in vitro laboratory tests and clinical in vivo experiments have been devised, analyzed, and published. The purpose of this review is to provide a current overview of bond strength testing methods and their applicability to the characterization of dental adhesives. Regardless of the method employed, subtle variations in sample preparation may already severely impact test results, usually necessitating at least co-testing of a well-known internal reference to allow conclusive interpretation. This article attempts to list and discuss the most influential parameters, such as substrate nature, age, health status, storage, clinically relevant pre-treatment, and sample preparation. Special attention is devoted to the last aspect, as numerous publications have stressed the tremendous influence of preparatory parameters on the validity and scope of obtained data. Added to the large variety of such factors, an equally large diversity of load-applying procedures exists to actually quantify adhesion between composites and dental hard substance. This article summarizes the basics of macro and micro approaches to shear and tensile bond strength testing, as well as push- and pull-out tests. The strengths and weaknesses inherent to each method and influential test parameters are reviewed and methods for

  3. Fracture toughness of experimental dental composites aged in ethanol.

    PubMed

    Ferracane, J L; Berge, H X

    1995-07-01

    Fracture toughness (KIc) is an intrinsic property which may be related to the ability of a restorative material to resist fracture and abrasion. This property may change for a dental composite restorative due to the effects of various oral solvents. The hypothesis to be tested was that aging in ethanol would cause a reduction in the fracture toughness of dental composites, and that the extent of this reduction might be dependent upon certain compositional variables. The fracture toughnesses of three series of experimental composites with various degrees of conversion, filler volume, and percent of silane-treated fillers were compared after the composites were aged for periods of one month and six months in 75% ethanol/water, a solvent which serves as a food-simulating liquid. An unfilled Bis-GMA/TEGDMA resin served as the control. All composites, with the exception of one subjected to a post-light-curing heat treatment, experienced a significant reduction (from 30 to 56%) in KIc after being aged in 75% ethanol for six months. A similar reduction in KIc of 58% for the unfilled resin suggested that the reduction for the composites was due to a weakening of the resin matrix, which facilitated crack propagation. A simultaneous reduction in microhardness was also demonstrated. One month of aging in ethanol also produced large reductions in KIc for specimens with insufficient cure and minimal filler volume, suggesting that the properties of the resin matrix predominated for these composites.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7560394

  4. A Review of Developments in Computer-Based Systems to Image Teeth and Produce Dental Restorations

    PubMed Central

    Rekow, E. Dianne; Erdman, Arthur G.; Speidel, T. Michael

    1987-01-01

    Computer-aided design and manufacturing (CAD/CAM) make it possible to automate the creation of dental restorations. Currently practiced techniques are described. Three automated systems currently under development are described and compared. Advances in computer-aided design and computer-aided manufacturing (CAD/CAM) provide a new option for dentistry, creating an alternative technique for producing dental restorations. It is possible to create dental restorations that are automatically produced and meet or exceed current requirements for fit and occlusion.

  5. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads.

    PubMed

    Chun, Keyoung Jin; Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130-135, 86.6-124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  6. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads

    PubMed Central

    Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130–135, 86.6–124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  7. Nonlinear finite element modeling of dental composite polymerization behavior

    NASA Astrophysics Data System (ADS)

    Laughlin, Gayle A.

    2003-07-01

    Polymerization shrinkage has been one of the primary shortcomings preventing the use of resin composites as a universal dental restorative material. This shrinkage of the bonded restoration causes residual stresses in the composite which in turn are transferred to the adhesive interface. The deleterious effects of this stress environment include compromise of the interface itself and the decrease in the mechanical properties of the cured composite. Novel materials which claim to produce less shrinkage have been presented as a new class of restorative materials that could reduce the effects of this problem. One difficulty in assessing the actual in vivo benefits of these new materials is the fact that there is currently no direct way to measure the stress environment at the composite/tooth clinical interface. Computer modeling using finite element analysis (FEA) could provide helpful information regarding the clinical stress performance of dental composites. The purpose of this study was to develop a model that accurately simulates the nonlinear polymerization behavior of light-cured dental composites using a commercial FEA program, which could be accessible for future research. Two phases were needed to accomplish this purpose. First, a data collection phase included volumetric shrinkage, shrinkage stress, tooth analog strain, and dynamic mechanical analysis experiments. Three composites, a standard methacrylate(Z250) and two experimental low stress epoxy-based composites (oxirane and silorane), were tested. The experimental results revealed an intriguing range of polymerization behavior exhibited by the three composites, indicating that the development of a low stress composite is possible. The information gathered from this phase supplied the necessary material input for the computer modeling, and provided empirical validation data for the model solutions. In the second modeling phase, an FEA approach based on a elastic/viscoplastic material model was used to

  8. Rubber-Toughening of Dimethacrylate Dental Composite Resin

    PubMed Central

    Lee, Valerie A.; Cardenas, H. Lee; Rawls, H. Ralph

    2010-01-01

    Dimethacrylate dental composite resins exhibit inherently low toughness. Toughening of these materials may reduce the incidence of marginal and bulk fracture of composite restorations. Objective: To determine if dimethacrylate dental restorative materials can be rubber-toughened, and if so, to identify a possible mechanism. Methods: A filler composed of aggregates of polybutadiene/silica as well as irregularly-shaped silica slabs was produced by mixing silica with polybutadiene in dichloromethane. The dried filler was subsequently ground and sieved to <25μm. Polybutadiene/silica ratios were varied from 0:1 (control) to 0.5:1. EDAX analysis verified the composition of the complex filler. Filler was added to a bis-GMA/bis-EMA/TEGDMA resin system and fractured in 3-point bend test mode at a crosshead speed of 1mm/min. In addition, 1 bar was fractured at a crosshead speed of 0.001mm/min in order to identify a possible mechanism for toughening. Results: In specimens fractured at 1mm/min, flexural modulus is increased or maintained and flexural strength and energy to break increase as the amount of polybutadiene in the aggregates increases. Cavitation of high-rubber-containing aggregates is demonstrated. In the one specimen fractured at 0.001mm/min, a marked increase in size of high-rubber-containing aggregates along with severe shear damage in the surrounding matrix is shown, suggesting that cavitation with subsequent absorption of energy during shear yielding is the likely mechanism behind the increase in energy to break in bars fractured at 1mm/min. Significance: These results indicate that dimethacrylate dental composite materials can be rubber toughened, which may potentially reduce marginal and bulk fractures of composite restorations, and consequently extend their service lifetime. PMID:20583305

  9. Matching the optical properties of direct esthetic dental restorative materials to those of human enamel and dentin

    NASA Astrophysics Data System (ADS)

    Ragain, James Carlton, Jr.

    One of the goals of the restorative dentist is to restore the appearance of the natural dentition. Clinical matching of teeth and restorative materials are seldom accurate and shade selection techniques are subjective. The first specific aim of this research was to characterize the optical absorption and scattering that occurs within enamel, dentin, and composite resin and compomer restorative materials and to relate those phenomena to translucency and color. The second aim was to evaluate small color differences among composite restorative materials which would be detectable by humans. The last aim was to lay the foundation for developing an improved model of specifying layers of dental restorative materials in order to match the translucency and color to those of human enamel. The Kubelka-Munk theory was validated for enamel, dentin, and the restorative materials. These tissues and materials were then characterized in terms of their color parameters. Tooth cores were also characterized in terms of color space parameters. Human subjects were evaluated for their abilities to discriminate small color differences in the dental composite resin materials. The following conclusions were derived from this study: (1) Kubelka-Munk theory accurately predicts the diffuse reflectance spectra of enamel, dentin, and the direct esthetic dental restorative materials studied. (2) Scattering and absorption coefficients of the dental tissues and esthetic restorative materials can be directly calculated from diffuse reflectance measurements of a uniformly thick slab of tissue/material using black and white backings and the appropriate refractive index. (3) For tooth cores, there is a positive correlation between L* and b* and a negative correlation between L* and a*. (4) The range of translucency parameters for the restorative materials studied does not match those of enamel and dentin. (5) None of the shades of the dental composite resin restorative materials studied fit into the

  10. Degradation, Fatigue, and Failure of Resin Dental Composite Materials

    SciTech Connect

    Drummond, J.L.

    2008-11-03

    The intent of this article is to review the numerous factors that affect the mechanical properties of particle- or fiber-filler-containing indirect dental resin composite materials. The focus will be on the effects of degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed-mode loading on flexure strength and fracture toughness. Several selected papers will be examined in detail with respect to mixed and cyclic loading, and 3D tomography with multi-axial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and/or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection); after that time period, failure most often results from secondary decay.

  11. Degradation, fatigue and failure of resin dental composite materials

    PubMed Central

    Drummond, James L.

    2008-01-01

    The intent of this article is to review the numerous factors that affect the mechanical properties of particle or fiber filler containing, indirect dental resin composite materials. The focus will be on degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed mode loading on the flexure strength and fracture toughness. Next several selected papers will be examined in detail with respect to mixed and cyclic loading and then an examination of 3D tomography using multiaxial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection) and after that time period from secondary decay. PMID:18650540

  12. Dental Therapy Assistant: Quality of Restorations Placed and Finished.

    ERIC Educational Resources Information Center

    Heid, Theodore H.; Bair, Jeffrey H.

    The U.S. Army Dental Corps has implemented a new concept of dental care delivery, formally identified as the Improved Dental Care Delivery System. The concept is based on the conservation of professional manpower resources through the use of dental treatment teams employing expanded duty dental assistants. Dental Therapy Assistant (DTA) is the…

  13. Assessment of exposures and potential risks to the US adult population from wear (attrition and abrasion) of gold and ceramic dental restorations.

    PubMed

    Richardson, G Mark; Clemow, Scott R; Peters, Rachel E; James, Kyle J; Siciliano, Steven D

    2016-01-01

    Little has been published on the chemical exposures and risks of dental restorative materials other than from dental amalgam and composite resins. Here we provide the first exposure and risk assessment for gold (Au) alloy and ceramic restorative materials. Based on the 2001-2004 US National Health and Nutrition Examination Survey (NHANES), we assessed the exposure of US adults to the components of Au alloy and ceramic dental restorations owing to dental material wear. Silver (Ag) is the most problematic component of Au alloy restorations, owing to a combination of toxicity and proportional composition. It was estimated that adults could possess an average of four tooth surfaces restored with Au alloy before exceeding, on average, the reference exposure level (REL) for Ag. Lithium (Li) is the most problematic component of dental ceramics. It was estimated that adults could possess an average of 15 tooth surfaces restored with ceramics before exceeding the REL for Li. Relative risks of chemical exposures from dental materials decrease in the following order: Amalgam>Au alloys>ceramics>composite resins. PMID:25805253

  14. Marginal integrity evaluation of dental composite using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Stan, Adrian-Tudor; Cojocariu, Andreea-Codruta; Antal, Anca Adriana; Topala, Florin; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian Gh.

    2016-03-01

    In clinical dental practice it is often difficult or even impossible to distinguish and control interfacial adhesive defects from adhesive restorations using visual inspection or other traditional diagnostic methods. Nonetheless, non-invasive biomedical imaging methods like Optical Coherence Tomography (OCT) may provide a better view in this diagnostic outline. The aim of this study is to explore evaluations of the marginal adaptation of class I resin composites restorations using Time Domain (TD) OCT. Posterior human teeth have been chosen for this study. The teeth were stored in 0.9% physiological saline solution prior to use. A classical round-shaped class I cavity was prepared and cavities were restored with Charisma Diamond composite by Heraeus Kulzer and using a system of etch and rinse boding. The specimens were subjected to water storage and then to thermo-cycling. Three dimensional (3-D) scans of the restoration were obtained using a TD-OCT system centered at a 1300 nm wavelength. Open marginal adaptation at the interfaces and gaps inside the composite resins materials were identified using the proposed method. In conclusion, OCT has numerous advantages which justify its use for in vitro, as well as for in vivo studies. It can therefore be considered for non-invasive and fast detection of gaps at the restoration interface.

  15. Studies on microleakage associated with visible light cured dental composites.

    PubMed

    Krishnan, V K; Bindhu, D B; Manjusha, K

    1996-04-01

    The objective of this investigation was twofold: 1) to determine the extent of microleakage associated with two visible light cured dental composites, one of which is an indigenously developed light cure composite (chitra light cure system) compared with a commercially available control material (Prisma APH light cure system), and 2) to study the effect of using bonding agents upon the above phenomena. The bonding agents used along with the above composites during restoration were chitra bonding agent system containing chitra primer/chitra resin and a control (Probond) which was purchased commercially. A comparison of microleakage in freshly restored human premolar teeth by silver nitrate staining technique was made during the above study. Cavities were restored with both composites with and without bonding agents, stored in 50 percent silver nitrate, and sections were cut after developing. The microtomed sections were observed under the optical light microscope and scanning electron microscope. Results indicate that bonding agents are mandatory for effective bonding at the tooth/resin interface and subsequent reduction in marginal leakage. Chitra bonding agent showed excellent adhesive bonding characteristics at the dentine/composite interface with minimal marginal leakage compared to the control bonding system. The chitra light cure composite material also showed lower shrinkage characteristics compared to Prisma APH composite. PMID:8859406

  16. Characterization of dental composite curing kinetics using dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Wells-Gray, Elaine M.; Kirkpatrick, Sean J.; Sakaguchi, Ron L.

    2009-02-01

    Polymer resin composites are a class of widely used restorative dental materials that undergo a complex polymerization curing process that has been the subject of substantial research. This study uses speckle correlation methods based on dynamic light scattering as a tool to monitor the rate and extent of dental composite polymerization during and after photo-curing. Thin disc-shaped samples (<2mm) were constructed using composite consisting of 50:50 BisGMA/TEGDMA resin, quartz silica filler particles, and camphorquinone as photo-initiator. A 633 nm HeNe laser beam was used to probe the top surface of the sample via a backscattered speckle pattern, while the bottom surface was illuminated with a halogen curing lamp (peak wavelength=470nm) to initiate the polymerization reaction. The speckle patterns were recorded with a CCD camera, and stored as a 'speckle cube' for post processing. Correlation values of the intensity fluctuation were calculated on a pixel-by-pixel basis for pairs of subsequent speckle images and then ensemble averaged. Results show a sharp decrease in correlation at the onset of curing, indicating a large amount of double bond conversion and movement within the composite. Correlation values then quickly increase, eventually reaching a plateau near unity, indicating cessation of molecular rearrangement. The kinetic behavior demonstrated by our correlation curves are in good agreement with curing data found in the literature, and demonstrate the usefulness of this technique for monitoring dental composite curing.

  17. Selective removal of esthetic composite restorations with spectral guided laser ablation

    PubMed Central

    Yi, Ivana; Chan, Kenneth H.; Tsuji, Grant H.; Staninec, Michal; Darling, Cynthia L.; Fried, Daniel

    2016-01-01

    Dental composites are used for a wide range of applications such as fillings for cavities, adhesives for orthodontic brackets, and closure of gaps (diastemas) between teeth by esthetic bonding. Anterior restorations are used to replace missing, diseased and unsightly tooth structure for both appearance and function. When these restorations must be replaced, they are difficult to remove mechanically without causing excessive removal or damage to enamel because dental composites are color matched to teeth. Previous studies have shown that CO2 lasers have high ablation selectivity and are well suited for removal of composite on occlusal surfaces while minimizing healthy tissue loss. A spectral feedback guidance system may be used to discriminate between dental composite and dental hard tissue for selective ablation of composite material. The removal of composite restorations filling diastemas is more challenging due to the esthetic concern for anterior teeth. The objective of this study is to determine if composite spanning a diastema between anterior teeth can be removed by spectral guided laser ablation at clinically relevant rates with minimal damage to peripheral healthy tissue and with higher selectivity than a high speed dental hand-piece. PMID:26997742

  18. Selective removal of esthetic composite restorations with spectral guided laser ablation

    NASA Astrophysics Data System (ADS)

    Yi, Ivana; Chan, Kenneth H.; Tsuji, Grant H.; Staninec, Michal; Darling, Cynthia L.; Fried, Daniel

    2016-02-01

    Dental composites are used for a wide range of applications such as fillings for cavities, adhesives for orthodontic brackets, and closure of gaps (diastemas) between teeth by esthetic bonding. Anterior restorations are used to replace missing, diseased and unsightly tooth structure for both appearance and function. When these restorations must be replaced, they are difficult to remove mechanically without causing excessive removal or damage to enamel because dental composites are color matched to teeth. Previous studies have shown that CO2 lasers have high ablation selectivity and are well suited for removal of composite on occlusal surfaces while minimizing healthy tissue loss. A spectral feedback guidance system may be used to discriminate between dental composite and dental hard tissue for selective ablation of composite material. The removal of composite restorations filling diastemas is more challenging due to the esthetic concern for anterior teeth. The objective of this study is to determine if composite spanning a diastema between anterior teeth can be removed by spectral guided laser ablation at clinically relevant rates with minimal damage to peripheral healthy tissue and with higher selectivity than a high speed dental handpiece.

  19. Laser equipment for investigation of light distribution in dental tissues and restorative materials

    NASA Astrophysics Data System (ADS)

    Grisimov, Vladimir N.; Smirmov, Alexander V.; Stafeev, Sergey C.

    1997-04-01

    The description of experimental set-up for investigation of light scattering in dental tissue and dental restorative material is presented. The set-up includes the light source (He-Ne laser), beam shaping light polarization control unit and registration device. The latter represents the computer interfaced CCD-camera. The experimental results of side light scattering in enamel/dentin and in double-layer porcelain are represented. The results of this research may be useful for aesthetic dental restorations.

  20. Heat generation caused by ablation of dental restorative materials with an ultra short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Braun, Andreas; Wehry, Richard; Brede, Olivier; Frentzen, Matthias; Schelle, Florian

    2011-03-01

    The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an Ultra Short Pulse Laser (USPL) system. Specimens of phosphate cement (PC), ceramic (CE) and composite (C) were used. Ablation was performed with an Nd:YVO4 laser at 1064 nm and a pulse length of 8 ps. Heat generation during laser ablation depended on the thickness of the restoration material. A time delay for temperature increase was observed in the PC and C group. Employing the USPL system for removal of restorative materials, heat generation has to be considered.

  1. Dental composites and amalgam and physical development in children.

    PubMed

    Maserejian, N N; Hauser, R; Tavares, M; Trachtenberg, F L; Shrader, P; McKinlay, S

    2012-11-01

    Resin-based composite dental restoration materials may release bisphenol-A, an endocrine-disrupting chemical. Using secondary analysis of a randomized clinical safety trial of amalgam vs. composites, we tested the hypothesis that dental restoration materials affect children's growth. Children (N = 218 boys, N = 256 girls) aged 6 to 10 yrs at baseline with ≥ 2 decayed posterior teeth were randomized to amalgam or composites (bisphenol-A-diglycidyl-dimethacrylate composite for permanent teeth, urethane-dimethacrylate compomer for primary teeth) for treatment of posterior caries throughout follow-up. Primary outcomes for this analysis were 5-year changes in BMI-for-age z-scores, body fat percentage (BF%), and height velocity; exploratory analyses (n = 113) examined age at menarche. Results showed no significant differences between treatment assignment and changes in physical development in boys [(composites vs. amalgam) BF%, 4.9 vs. 5.7, p = 0.49; (BMI-z-score) 0.13 vs. 0.25, p = 0.36] or girls (8.8 vs. 7.7, p = 0.95; 0.36 vs. 0.21, p = 0.49). Children with more treatment on primary teeth had greater increases in BF% regardless of material type. Girls assigned to composites had lower risk of menarche during follow-up (hazard ratio = 0.57, 95% CI 0.35-0.95). Overall, there were no significant differences in physical development over 5 years in children treated with composites or amalgam. Additional studies examining these restoration materials in relation to age at menarche are warranted (clinicaltrials.gov number NCT00065988). PMID:22972857

  2. Water aging reverses residual stresses in hydrophilic dental composites.

    PubMed

    Park, J W; Ferracane, J L

    2014-02-01

    Dental composites develop residual stresses during polymerization due to shrinkage. These stresses may change with time because of relaxation and water sorption in the oral environment. This phenomenon is likely dependent on the composition of the materials, specifically their hydrophilic characteristics, and could result in deleterious stresses on restorative materials and tooth structure. The purpose of this experiment was to use the thin ring-slitting method to compare the residual stress generated within composite materials of varying hydrophilicity when aged in wet and dry conditions after polymerization. Water sorption, solubility, elastic modulus, and residual stresses were measured in 6 commercial composites/cements aged in water and dry conditions. The self-adhesive resin cement showed the highest water sorption and solubility. All composites showed initial residual contraction stresses, which were maintained when aged dry. Residual stresses in 2 of the self-adhesive cements and the polyacid-modified composite aged in wet conditions resulted in a net expansion. This experiment verified that residual shrinkage stresses in dental composites can be reversed during aging in water, resulting in a net expansion, with the effect directly related to their hydrophilic properties. PMID:24272790

  3. Effects of cavity configuration on composite restoration.

    PubMed

    Choi, Kyoung-Kyu; Ryu, Gil-Joo; Choi, Seung-Mo; Lee, Min-Jo; Park, Sang-Jin; Ferracane, Jack L

    2004-01-01

    This study evaluated the effects of various cavity configurations on the bond strength, microleakage, flexural strength and elastic modulus of a hybrid (Clearfil AP-X) and a microhybrid (Esthet-X) composite restorative. After the specimens were made with C-factors of less than 1, 2.4 and 3.4, flexural strength and elastic modulus were evaluated in three-point bending using a mechanical testing machine. Fragments of the fractured specimens were selected randomly and the fracture surfaces were examined in SEM. To evaluate the microtensile bond strength and microleakage of composite restorations in bovine cavities, C-factors (ratio of bonded to non-bonded cavity surface) were controlled as 1.0, 2.3, 3.0 and 3.7. All specimens were stored in distilled water at 37 degrees C for 24 hours and tested in a universal testing machine (EZ Test, Shimadzu, Japan). For the microleakage test, teeth with restorations were stained with silver nitrate and examined by two examiners under a stereomicroscope at 40x magnification. The hybrid composite showed higher mechanical properties than the microhybrid composite. The flexural strength and elastic modulus of both composites decreased when polymerized under greater constraint, that is, with increasing C-factor. Mean microtensile bond strength to dentin was also decreased with increasing C-factor for both types of composites. Microleakage scores for the hybrid composite restorations were generally higher than the microhybrid composite. PMID:15279488

  4. Translucency of human teeth and dental restorative materials and its clinical relevance

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Keun

    2015-04-01

    The purpose was to review the translucency of human teeth and related dental materials that should be considered for the development of esthetic restorative materials. Translucency is the relative amount of light transmission or diffuse reflection from a substrate surface through a turbid medium. Translucency influences the masking ability, color blending effect, and the degree of light curing through these materials. Regarding the translucency indices, transmission coefficient, translucency parameter, and contrast ratio have been used, and correlations among these indices were confirmed. Translucency of human enamel and dentine increases in direct proportion to the wavelength of incident light in the visible light range. As for the translucency changes by aging, limited differences were reported in human dentine, while those for enamel proved to increase. There have been studies for the adjustment of translucency in dental esthetic restorative materials; the size and amount of filler and the kind of resin matrix were modified in resin composites, and the kind of ingredient and the degree of crystallization were modified in ceramics. Based on the translucency properties of human enamel and dentine, those of replacing restorative materials should be optimized for successful esthetic rehabilitation. Biomimetic simulation of the natural tooth microstructure might be a promising method.

  5. [Atraumatic restorative treatment in relation to pain, discomfort and dental treatment anxiety].

    PubMed

    Frencken, J E F M; Flohil, K A; de Baat, C

    2014-01-01

    Dental treatment anxiety usually develops during childhood due to a bad experience and the dental drill as well as the injection needle are the most common causes. The Atraumatic Restorative Treatment provides the opportunity to provoke little or no dental treatment anxiety because only hand instruments are used and local anaesthesia is seldom required. Several scientific studies have indicated that the Atraumatic Restorative Treatment causes less pain, discomfort and anxiety by comparison with conventional treatments. Therefore, the Atraumatic Restorative Treatment is considered to be promising for the treatment of carious lesions in anxious children and adults, and potentially also for patients suffering from dental treatment phobia. Furthermore, the Atraumatic Restorative Treatment may be indicated as the primary treatment method in children to prevent dental treatment anxiety and treatment under general anaesthesia. These conclusions must still be confirmed with responsible scientific research. PMID:25174188

  6. Understanding dental CAD/CAM for restorations - dental milling machines from a mechanical engineering viewpoint. Part A: chairside milling machines.

    PubMed

    Lebon, Nicolas; Tapie, Laurent; Duret, Francois; Attal, Jean-Pierre

    2016-01-01

    The dental milling machine is an important device in the dental CAD/CAM chain. Nowadays, dental numerical controlled (NC) milling machines are available for dental surgeries (chairside solution). This article provides a mechanical engineering approach to NC milling machines to help dentists understand the involvement of technology in digital dentistry practice. First, some technical concepts and definitions associated with NC milling machines are described from a mechanical engineering viewpoint. The technical and economic criteria of four chairside dental NC milling machines that are available on the market are then described. The technical criteria are focused on the capacities of the embedded technologies of these milling machines to mill both prosthetic materials and types of shape restorations. The economic criteria are focused on investment costs and interoperability with third-party software. The clinical relevance of the technology is assessed in terms of the accuracy and integrity of the restoration. PMID:27027102

  7. The effect of a mouthrinse containing essential oils on dental restorative materials.

    PubMed

    von Fraunhofer, J A; Kelley, J I; DePaola, L G; Meiller, T F

    2006-01-01

    Mouthrinses that contain essential oils are effective for controlling plaque and periodontal disease. Recent studies have shown that such mouthrinses are effective at preventing the formation of biofilm in dental unit waterlines. However, there is no information in the literature regarding the effect of such mouthrinses on restorative materials used within the oral cavity. Specimens of three common restorative materials (a glass ionomer, a composite resin, and amalgam) were subjected to continuous exposure to Listerine and distilled water for 10 days; at that time, the strength, fluid sorption, and surface appearance of the specimens were compared. Specimens of the test materials also were placed in intraoral devices; volunteer patients wore these devices for 12 hours per day for a period of 10 days. During that time, the patients were instructed to rinse twice daily for 30 seconds with Listerine Cool Mint or a non-active mouthrinse. After 10 days, the specimens were salvaged from the devices and inspected by visible and SEM examination. This study indicates that routine use of mouthrinses containing essential oils (or even prolonged exposure to such mouthrinses) has no adverse effects on restorative materials that might be expected to react to such mixtures because of their chemical compositions. It was concluded that active mouthrinses do not appear to have any adverse effects on a variety of restorative biomaterials. PMID:17134077

  8. Cluster Effects in a National Dental PBRN Restorative Study

    PubMed Central

    Litaker, M.S.; Gordan, V.V.; Rindal, D.B.; Fellows, J.L.; Gilbert, G.H.

    2013-01-01

    Items in clusters, such as patients of the same clinician or teeth within the same patient, tend to be more similar than items from different groups. This within-group similarity, represented by the intraclass correlation coefficient (ICC), reduces precision, yielding less statistical power and wider confidence intervals, compared with non-clustered samples of the same size. This must be considered in the design of studies including clusters. We present ICC estimates from a study of 7,826 restorations placed in previously unrestored tooth surfaces of 4,672 patients by 222 clinicians in the National Dental Practice-Based Research Network, as a resource for sample size planning in restorative studies. Our findings suggest that magnitudes of ICCs in practice-based research can be substantial. These can have large effects on precision and the power to detect treatment effects. Generally, we found relatively large ICCs for characteristics that are influenced by clinician choice (e.g., 0.36 for rubber dam use). ICCs for outcomes within individual patients, such as tooth surfaces affected by a caries lesion, tended to be smaller (from 0.03 to 0.15), but were still sufficiently large to substantially affect statistical power. Clustering should be taken into account in the design of oral health studies and derivation of statistical power estimates for these studies (ClinicalTrials.gov, NCT00847470). PMID:23857643

  9. Cluster Effects in a National Dental PBRN restorative study.

    PubMed

    Litaker, M S; Gordan, V V; Rindal, D B; Fellows, J L; Gilbert, G H

    2013-09-01

    Items in clusters, such as patients of the same clinician or teeth within the same patient, tend to be more similar than items from different groups. This within-group similarity, represented by the intraclass correlation coefficient (ICC), reduces precision, yielding less statistical power and wider confidence intervals, compared with non-clustered samples of the same size. This must be considered in the design of studies including clusters. We present ICC estimates from a study of 7,826 restorations placed in previously unrestored tooth surfaces of 4,672 patients by 222 clinicians in the National Dental Practice-Based Research Network, as a resource for sample size planning in restorative studies. Our findings suggest that magnitudes of ICCs in practice-based research can be substantial. These can have large effects on precision and the power to detect treatment effects. Generally, we found relatively large ICCs for characteristics that are influenced by clinician choice (e.g., 0.36 for rubber dam use). ICCs for outcomes within individual patients, such as tooth surfaces affected by a caries lesion, tended to be smaller (from 0.03 to 0.15), but were still sufficiently large to substantially affect statistical power. Clustering should be taken into account in the design of oral health studies and derivation of statistical power estimates for these studies (ClinicalTrials.gov, NCT00847470). PMID:23857643

  10. Finite element analysis of the residual thermal stresses on functionally gradated dental restorations.

    PubMed

    Henriques, B; Miranda, G; Gasik, M; Souza, J C M; Nascimento, R M; Silva, F S

    2015-10-01

    The aim of this work was to study, using the finite element method (FEM), the distribution of thermal residual stresses arising in metal-ceramic dental restorations after cooling from the processing temperature. Three different interface configurations were studied: with conventional sharp transition; one with a 50% metal-50% ceramic interlayer; and one with a compositionally functionally gradated material (FGM) interlayer. The FE analysis was performed based on experimental data obtained from Dynamic Mechanical Analysis (DMA) and Dilatometry (DIL) studies of the monolithic materials and metal/ceramic composites. Results have shown significant benefits of using the 50% metal-50% ceramic interlayer and the FGM interlayer over the conventional sharp transition interface configuration in reduction of the thermal residual stress and improvement of stress profiles. Maximum stresses magnitudes were reduced by 10% for the crowns with 50% metal-50% ceramic interlayer and by 20% with FGM interlayer. The reduction in stress magnitude and smoothness of the stress distribution profile due to the gradated architectures might explain the improved behavior of these novel dental restorative systems relative to the conventional one, demonstrated by in-vitro studies already reported in literature. PMID:26122789

  11. Restoration of anterior teeth using an indirect composite technique. Case report

    PubMed Central

    GARGARI, M.; CERUSO, F.M.; PUJIA, A.; PRETE, V.

    2013-01-01

    SUMMARY Objective. This article presents a case report of restoration of anterior teeth using an indirect technique with composite veneers in order to restore the dental anatomy and to provide aesthetic and function of anterior teeth. Materials and methods. A treatment of upper anterior teeth with indirect micro-hybrid composite restoration was proposed to a 40-year-old woman with old discolored and fractured ceramic veneers. Upper six anterior teeth were prepared and, after impressions with VPS of maxillary arche, the composite veneers were placed. Discussion and results. There are several advantages offered by indirect techniques compared to direct techniques. The increased practice of veneering technique with indirect composites is due to improvement in the properties of composite materials in the last years. The results are very favourable and the patient is satisfied. Conclusions. The restorations with composite veneers have proved durable and aesthetic, protect tooth structure and aesthetic and function is predictably re-established. PMID:24971164

  12. Resin Composites Reinforced by Nanoscaled Fibers or Tubes for Dental Regeneration

    PubMed Central

    Li, Xiaoming; Liu, Wei; Sun, Lianwen; Aifantis, Katerina E.; Yu, Bo; Fan, Yubo; Cui, Fuzhai; Watari, Fumio

    2014-01-01

    It has been stated clearly that nanofillers could make an enhancement on the mechanical performances of dental composites. In order to address current shortage of traditional dental composites, fillers in forms of nanofibers or nanotubes are broadly regarded as ideal candidates to greatly increase mechanical performances of dental composites with low content of fillers. In this review, the efforts using nanofibers and nanotubes to reinforce mechanical performances of dental composites, including polymeric nanofibers, metallic nanofibers or nanotubes, and inorganic nanofibers or nanotubes, as well as their researches related, are demonstrated in sequence. The first purpose of current paper was to confirm the enhancement of nanofibers or nanotubes' reinforcement on the mechanical performances of dental restorative composite. The second purpose was to make a general description about the reinforcement mechanism of nanofibers and nanotubes, especially, the impact of formation of interphase boundary interaction and nanofibers themselves on the advanced mechanical behaviors of the dental composites. By means of the formation of interface interaction and poststretching nanofibers, reinforced effect of dental composites by sorts of nanofibers/nanotubes has been successfully obtained. PMID:24982894

  13. A useful and non-invasive microanalysis method for dental restoration materials

    NASA Astrophysics Data System (ADS)

    Hosoki, M.; Satsuma, T.; Nishigawa, K.; Takeuchi, H.; Asaoka, K.

    2012-12-01

    The elemental analysis of intraoral dental restorations provides considerable information for the treatment of dental metal allergy. Elemental analyses require specific instruments and complicated procedures, so this examination is not commonly carried out in private dental clinics. We describe a novel, simple and useful micro-analytical method for dental metal restorations. Micro metal dust was obtained by polishing the surface of restorative metal material with an unused silicone point (SUPER-SNAP). The metal dust on the silicone point was then rubbed onto adhesive tape, and this tape was covered with polyethylene film. The amount of metal dust material was <20 μg. An energy dispersive X-ray fluorescence spectrometer was used to carry out the elementary analysis of the metal dust on the polyethylene film. Three types of dental metal alloy materials of known components were examined. The results of elementary analyses were compared with the specifications provided by the manufacturer. The same procedure was carried out for three dental metal restorations of an adult female volunteer in vivo. The results of elemental analyses for five alloy materials exactly matched the product specification. Three metal samples obtained from intraoral restoration were also available for elemental analyses. The distinct advantage of this method is that it enables sample extraction without an invasive effect for the restoration. The metal sample is in a polyethylene film, so it is easy to mail it for inspection at specialist institutes yet it can be also be used in general dental clinics.

  14. A study of composite restorations as a tool in forensic identification

    PubMed Central

    Hemasathya, Bahavathi Ananthan; Balagopal, Sundaresan

    2013-01-01

    Introduction: Comparing ante-mortem and post-mortem dental data is a principal method of identification in forensic odontology. Radiographic images of amalgam have been used in dental forensics for identification due to their unique appearance. Aim: The aim of this study was to investigate whether radio-opaque composite restorations have a potential for identification in forensic odontology. Materials and Methods: Thirty typodont mandibular first molar teeth were prepared with Class-II (proximo-occlusal) cavities and restored with a radio-opaque composite (Tetric N-Ceram). Two sets of standardized radiographs were taken from the 30 teeth, keeping the radiological parameters constant. One set of these 30 radiographs was named as SET 1. Ten randomly chosen radiographs from the other set and two other radiographs of Class-II composite restorations in typodont teeth constituted SET 2. Thirty dentally trained examiners were asked to match the 12 radiographic images of SET 2 with those of SET 1. Results: The results show that 15 examiners were able to correctly match all the 12 images. Statistical analysis was done using kappa statistical test. Conclusion: This study shows that, if the post-mortem radiographs are accurate duplicates of ante-mortem radiographs of composite restorations, then the shape of the composite restoration is unique and can be used for identification. PMID:23960413

  15. Multi-material laser densification (MMLD) of dental restorations: Process optimization and properties evaluation

    NASA Astrophysics Data System (ADS)

    Li, Xiaoxuan

    This Ph.D. thesis proposes to investigate the feasibility of laser-assisted dental restoration and to develop a fundamental understanding of the interaction between laser beam and dental materials. Traditional dental restorations are produced by the porcelain-fused-to-metal (PFM) process, in which a dental restoration is cast from a metallic alloy and then coated with dental porcelains by multiple furnace-firing processes. PFM method is labor-intensive and hence very expensive. In order to fabricate dental restoration units faster and more cost-effectively, the Solid Freeform Fabrication (SFF) technique has been employed in this study. In particular, a Multi-Material Laser Densification (MMLD) process has been investigated for its potential to fabricate artificial teeth automatically from 3-D computer dental tooth files. Based on the principle of SFF, the MMLD process utilizes a micro-extruder system to deliver commercial dental alloy and porcelain slurry in a computer-controlled pattern line by line and layer by layer. Instead of firing the artificial tooth/teeth in a furnace, the extruded dental materials are laser scanned to convert the loose powder to a fully dense body. Different laser densification parameters including the densification temperature, laser output power, laser beam size, line dimension, ratio of the beam size to line width, beam scanning rate, processing atmosphere and pressure, dental powder state (powder bed or slurry), powder particle size, etc. have been used to evaluate their effects on the microstructures and properties of the laser densified dental body, and hence to optimize MMLD conditions. Furthermore, laser-scanning induced phase transformations in dental porcelains have been studied because the transformations have great impact on coefficient of thermal expansion (CTE) of dental porcelains, which should match that of dental alloy substrate. Since a single dental material line delivered by the MMLD system functions as a "construction

  16. Direct Composite Restorations to Mask Intrinsic Staining: An Eighteen-Year Follow-Up.

    PubMed

    Mondelli, Rafael Francisco Lia; Soares, Ana Flávia; Tostes, Bhenya Ottoni; Bombonatti, Juliana Fraga Soares

    2016-03-01

    In this case example, the use of direct composite resin allowed for a relatively simple, conservative treatment that provided excellent function and aesthetics, while preserving healthy dental tissue. The importance of continued follow-up and a periodic maintenance and minor repair process will ensure longevity of the restorations, as aesthetics, and the occlusion. PMID:27039546

  17. The Post-Amalgam Era: Norwegian Dentists’ Experiences with Composite Resins and Repair of Defective Amalgam Restorations

    PubMed Central

    Kopperud, Simen E.; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists’ satisfaction with alternative restorative materials and to explore dentists’ treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p < 0.01), employees in the Public Dental Service (PDS) (p < 0.01) and dentists working in counties with low dentist density (p = 0.03). There was a tendency towards choosing minimally invasive treatment among dentists who also avoided operative treatment of early approximal lesions (p < 0.01). Norwegian dentists showed positive attitudes towards composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations. PMID:27110804

  18. The Post-Amalgam Era: Norwegian Dentists' Experiences with Composite Resins and Repair of Defective Amalgam Restorations.

    PubMed

    Kopperud, Simen E; Staxrud, Frode; Espelid, Ivar; Tveit, Anne Bjørg

    2016-01-01

    Amalgam was banned as a dental restorative material in Norway in 2008 due to environmental considerations. An electronic questionnaire was sent to all dentists in the member register of the Norwegian Dental Association (NTF) one year later, to evaluate dentists' satisfaction with alternative restorative materials and to explore dentists' treatment choices of fractured amalgam restorations. Replies were obtained from 61.3%. Composite was the preferred restorative material among 99.1% of the dentists. Secondary caries was the most commonly reported cause of failure (72.7%), followed by restoration fractures (25.1%). Longevity of Class II restorations was estimated to be ≥10 years by 45.8% of the dentists, but 71.2% expected even better longevity if the restoration was made with amalgam. Repair using composite was suggested by 24.9% of the dentists in an amalgam restoration with a fractured cusp. Repair was more often proposed among young dentists (p < 0.01), employees in the Public Dental Service (PDS) (p < 0.01) and dentists working in counties with low dentist density (p = 0.03). There was a tendency towards choosing minimally invasive treatment among dentists who also avoided operative treatment of early approximal lesions (p < 0.01). Norwegian dentists showed positive attitudes towards composite as a restorative material. Most dentists chose minimally- or medium invasive approaches when restoring fractured amalgam restorations. PMID:27110804

  19. The role of emergence profile in papilla maintenance after diastema closure with direct composite resin restorations.

    PubMed

    Sobrinho, Kleyver Nascimento; Lima, Liliane Motta de; Cohen-Carneiro, Flávia; Silva, Luciana Mendonça da; Martins, Leandro Moura; Pontes, Danielson Guedes

    2016-01-01

    The dental morphology usually determines the shape and volume of the interdental space, which must be filled by a dense connective tissue covered by oral epithelium to achieve pleasant esthetics. When composite resin restorations are placed to solve esthetic problems, the restorative procedure must be designed to allow the formation of healthy interdental papilla. This case report discusses aspects that should be considered when composite resin restorations are proposed for diastema closure. A 23-year-old man sought treatment for variations of space in the anterior dentition after orthodontic treatment. Direct composite resin restorations were placed in a way that respected the emergence profile, even though "black triangles" were evident immediately after the procedure. At the 45-day follow-up, complete closure of the interdental spaces by healthy papillae was observed. The emergence profile should be identified and respected when restorations are placed to obtain diastema closure because healthy periodontal tissues and acceptable esthetics depend on it. PMID:27148664

  20. Influence of gag reflex on dental attendance, dental anxiety, self-reported temporomandibular disorders and prosthetic restorations.

    PubMed

    Akarslan, Z Z; Yıldırım Biçer, A Z

    2013-12-01

    To assess the influence of gag reflex severity, assessed according to the short form of the patient part of Gagging Problem Assessment Questionnaire (GPA-pa SF), on the dental attendance, dental anxiety, self-reported temporomandibular disorder (TMD) symptoms and presence of prosthetic restorations among patients requiring prosthodontic treatment in Turkey. A total of 505 patients (305 women; mean age: 46·35 years, SD: 28·2 years) undergoing dental examination were administered a questionnaire containing questions regarding their age, gender, education level, dental attendance, TMD symptoms (limitation in jaw opening, muscle pain, pain/sounds in the temporomandibular jaw), the Turkish version of the Modified Dental Anxiety Scale (MDAS) and the GPA-pa SF. Subsequently, any prosthetic restoration was recorded by a dentist. Descriptive statistics, one-way analysis of variance (anova) and the chi-square test were used for statistical analysis. Differences were found between GPA-pa SF scores 0, 1 and 2 for education level (P = 0·001), MDAS scores (P = 0·003), self-reported TMD (P = 0·000) and prosthesis wear (P = 0·000), but not for attendance patterns (P = 0·826). Patients with gag reflex had lower education levels, higher levels of dental anxiety, more self-reported TMD symptoms and fewer fixed or removable prosthetic restorations than patients without gag reflex. Gag reflex has impacts on dental anxiety, self-reported TMD and prosthetic restorations, but not on dental attendance patterns, according to the results of the GPA-pa SF. PMID:24118087

  1. Cariogenic bacteria degrade dental resin composites and adhesives.

    PubMed

    Bourbia, M; Ma, D; Cvitkovitch, D G; Santerre, J P; Finer, Y

    2013-11-01

    A major reason for dental resin composite restoration replacement is related to secondary caries promoted by acid production from bacteria including Streptococcus mutans (S. mutans). We hypothesized that S. mutans has esterase activities that degrade dental resin composites and adhesives. Standardized specimens of resin composite (Z250), total-etch (Scotchbond Multipurpose, SB), and self-etch (Easybond, EB) adhesives were incubated with S. mutans UA159 or uninoculated culture medium (control) for up to 30 days. Quantification of the BisGMA-derived biodegradation by-product, bishydroxy-propoxy-phenyl-propane (BisHPPP), was performed by high-performance liquid chromatography. Surface analysis of the specimens was performed by scanning electron microscopy (SEM). S. mutans was shown to have esterase activities in levels comparable with those found in human saliva. A trend of increasing BisHPPP release throughout the incubation period was observed for all materials and was more elevated in the presence of bacteria vs. control medium for EB and Z250, but not for SB (p < .05). SEM confirmed the increased degradation of all materials with S. mutans UA159 vs. control. S. mutans has esterase activities at levels that degrade resin composites and adhesives; degree of degradation was dependent on the material's chemical formulation. This finding suggests that the resin-dentin interface could be compromised by oral bacteria that contribute to the progression of secondary caries. PMID:24026951

  2. Machinable glass-ceramics forming as a restorative dental material.

    PubMed

    Chaysuwan, Duangrudee; Sirinukunwattana, Krongkarn; Kanchanatawewat, Kanchana; Heness, Greg; Yamashita, Kimihiro

    2011-01-01

    MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892°C (second crystallization temperature+20°C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa√m) combined with the hardness to give a lower brittleness index (1.81 µm(-1/2)) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium mica-fluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM. PMID:21597218

  3. Characteristics Identified for Success by Restorative Dental Science Department Chairpersons.

    PubMed

    Wee, Alvin G; Weiss, Robert O; Wichman, Christopher S; Sukotjo, Cortino; Brundo, Gerald C

    2016-03-01

    The primary aim of this study was to determine the characteristics that current chairpersons in restorative dentistry, general dentistry, prosthodontics, and operative dentistry departments in U.S. dental schools feel are most relevant in contributing to their success. The secondary aim was to determine these individuals' rankings of the importance of a listed set of characteristics for them to be successful in their position. All 82 current chairs of the specified departments were invited to respond to an electronic survey. The survey first asked respondents to list the five most essential characteristics to serve as chair of a department and to rank those characteristics based on importance. Participants were next given a list of ten characteristics in the categories of management and leadership and, without being aware of the category of each individual item, asked to rank them in terms of importance for their success. A total of 39 chairpersons completed the survey (47.6% response rate; 83.3% male and 16.2% female). In section one, the respondents reported that leadership, vision, work ethic, integrity, communication, and organization were the most essential characteristics for their success. In section two, the respondents ranked the leadership characteristics as statistically more important than the management characteristics (p<0.0001) for being successful in their positions. PMID:26933102

  4. [Post-academic dental specialties. 11. Discomfort during atraumatic restorative treatment (ART) versus conventional restorative treatment].

    PubMed

    van Gemert-Schriks, M C M

    2007-05-01

    Although Atraumatic Restorative Treatment (ART) claims to be a patient-friendly method of treatment, little scientific proof of this is available. The aim of this study, therefore, was to acquire a reliable measurement of the degree of discomfort which children experience during dental treatment performed according to the ART approach and during the conventional method. A number of 403 Indonesian schoolchildren were randomly divided into 2 groups. In each child, one class II restoration was carried out on a deciduous molar either by means of ART or the use of rotary instruments (750 rpm). Discomfort scores were determined both by physiological measurements (heart rate) and behavioral observations (Venham scale). Venham scores showed a marked difference between the 2 groups, whereas heart rate scores only differed significantly during deep excavation. A correlation was found between Venham scores and heart rate measurements. Sex, initial anxiety and performing dentist were shown to be confounding variables. In conclusion it can be said that children treated according to the ART approach experience less discomfort than those treated with rotary instruments. PMID:17552299

  5. Understanding dental CAD/CAM for restorations--the digital workflow from a mechanical engineering viewpoint.

    PubMed

    Tapie, L; Lebon, N; Mawussi, B; Fron Chabouis, H; Duret, F; Attal, J-P

    2015-01-01

    As digital technology infiltrates every area of daily life, including the field of medicine, so it is increasingly being introduced into dental practice. Apart from chairside practice, computer-aided design/computer-aided manufacturing (CAD/CAM) solutions are available for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental solutions can be considered a chain of digital devices and software for the almost automatic design and creation of dental restorations. However, dentists who want to use the technology often do not have the time or knowledge to understand it. A basic knowledge of the CAD/CAM digital workflow for dental restorations can help dentists to grasp the technology and purchase a CAM/CAM system that meets the needs of their office. This article provides a computer-science and mechanical-engineering approach to the CAD/CAM digital workflow to help dentists understand the technology. PMID:25911827

  6. High elastic modulus nanopowder reinforced resin composites for dental applications

    NASA Astrophysics Data System (ADS)

    Wang, Yijun

    2007-12-01

    Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus <15 GPa. Chemical additives can also effectively raise the hardness to as much as 1.34 GPa. Besides>alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with

  7. Adhesive/Dentin Interface: The Weak Link in the Composite Restoration

    PubMed Central

    Spencer, Paulette; Ye, Qiang; Park, Jonggu; Topp, Elizabeth M.; Misra, Anil; Marangos, Orestes; Wang, Yong; Bohaty, Brenda S.; Singh, Viraj; Sene, Fabio; Eslick, John; Camarda, Kyle; Katz, J. Lawrence

    2010-01-01

    Results from clinical studies suggest that more than half of the 166 million dental restorations that were placed in the United States in 2005 were replacements for failed restorations. This emphasis on replacement therapy is expected to grow as dentists use composite as opposed to dental amalgam to restore moderate to large posterior lesions. Composite restorations have higher failure rates, more recurrent caries, and increased frequency of replacement as compared to amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and premature failure. Under in vivo conditions the bond formed at the adhesive/dentin interface can be the first defense against these noxious, damaging substances. The intent of this article is to review structural aspects of the clinical substrate that impact bond formation at the adhesive/dentin interface; to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface. PMID:20195761

  8. Caries prevalence and restorative dental services in some Pacific Islands.

    PubMed

    Speake, J D

    1980-08-01

    Caries prevalence rates at eight and eleven years of age were estimated according to WHO criteria in six Pacific Island countries and territories during the period 1975 to 1977. The components of the dental caries index (DIMF(T)) on a country or territory basis were examined and the dental care index calculated. Factors influencing the delivery of dental services in the region are discussed. PMID:6934741

  9. Comparison of the abrasive wear resistance between amalgams, hybrid composite material and different dental cements.

    PubMed

    Gil, F J; Espias, A; Sánchez, L A; Planell, J A

    1999-12-01

    This paper reports on the abrasion wear of various restorative dental materials (three amalgams and two dental cements and a hybrid composite material) commonly used in dentistry. The mechanical properties, surface roughness and the volume loss by abrasion were determined for the different materials studied. The results showed a better profile for the amalgams versus the composite materials due to the failure of the polymeric matrix of the latter materials. However, the amalgams exhibited corrosion observed by means of Scanning Electron Microscopy. PMID:10907431

  10. Time-dependent strength and fatigue resistance of dental direct restorative materials.

    PubMed

    Lohbauer, Ulrich; Frankenberger, Roland; Krämer, Norbert; Petschelt, Anselm

    2003-12-01

    Elastic modulus (EM), initial fracture strength (FS) and flexural fatigue limit (FFL) of dental restorative materials were measured in a simulated oral environment to correlate mechanical response under the influence of water with the chemical nature of the test materials under investigation. One resin composite (RC; Tetric Ceram, Ivoclar-Vivadent Corp., Liechtenstein), an ion-leaching resin composite (ILRC; Ariston pHc, Ivoclar-Vivadent Corp., Liechtenstein) a compomer (CO; Dyract AP, Dentsply Corp., USA) and a glass-ionomer cement (GIC; Ketac Molar, 3MEspe Corp., Germany) were tested. Static EM, FS and dynamic FFL experiments were performed. The FFL was determined under cyclic loading for 10(5) cycles in terms of a staircase approach. The materials were stored for 1, 8, 30, 90 and 180 days in 37 degrees C distilled water, respectively. The RC degraded over time due to water adsorption followed by failure within the resin matrix. The ILRC suffered from a pronounced decrease in FS as well as in FFL due to a constant ion-leaching and macroscopic crack growth. CO failed over time due to resin-filler interface cracking. The GIC exhibited improved mechanical performance over time due to a post-hardening mechanism. The results reveal the necessity for substantial preclinical evaluation of direct restorative materials. The material parameters under investigation are capable of predicting clinical performance over time. PMID:15348497

  11. Knowledge and practice of implant-retained restorations among dental students in Saudi Arabia

    PubMed Central

    Vohra, Fahim; Shah, Altaf Hussain; Zafar, Mohammad Sohail; Kola, Zaheer

    2015-01-01

    Objectives: The aim of the study was to assess the knowledge and practice of implant retained restorations (IRR) among senior dental students in Saudi Arabia. Methods: Four hundred questionnaires were distributed among senior dental students of five dental schools in Saudi Arabia. Student’s knowledge was assessed regarding which implant restoration [cement retained restoration (CRR) or screw retained restoration (SRR)] better provides the desired clinical properties. Students’ practice of IRR, perception of their knowledge and need for further education related to IRR were also assessed. Descriptive statistics and chi-square test were employed to assess collected data. Results: Three hundred and fifty four senior dental students responded at a response rate of 88.5%. Thirty three percent respondents did not have any practical experience of IRR. Students showed a clear preference for CRR with regards to aesthetics (71.4%), passive fit (55.3%), fabrication ease (57.3%) and fracture resistance (40%). SRR were considered to provide better retention (59.6%), soft tissue health (51.1%) and ease of retrievability (72%). Nearly 40% of students agreed that they did not get sufficient information related to IRR in undergraduate courses. Conclusions: Clinical training of IRR is compromised in the undergraduate curriculum in dental schools of Saudi Arabia. The knowledge of dental students regarding IRR was broadly in line with current evidence. PMID:26430416

  12. Clinical evaluation of direct composite restoration done for midline diastema closure – long-term study

    PubMed Central

    Prabhu, R.; Bhaskaran, S.; Geetha Prabhu, K. R.; Eswaran, M. A.; Phanikrishna, G.; Deepthi, B.

    2015-01-01

    Purpose of the Study: The aim of this study was to evaluate clinically the performance of composite resin used to restore midline diastema between the maxillary and mandibular central incisors. Methodology: Direct composite restorations were done for 45 patients with midline diastema between the maxillary and mandibular central incisors. Standard protocols were followed for the placement of composite resin for the diastema closure, and recall visits were made for every 6 months for a period of 60 months for evaluation of the success of these restorations made. Qualified dental personnel examined the restorations made. Results: Clinical evaluations were done after the restorations had been in place for an average of 6 months. Results indicate that none of the restorations were totally lost, and resulting in a 91% overall retention rate for the period of 60 months. About 62% of the restorations made had no noticeable color difference with that of the adjacent tooth, and gingival health indicated 73% of the sample was without any signs of inflammation. Conclusions: Composites restored for diastemas exhibit satisfactory survival rates placed with recommended placement protocols and without occlusal loading. PMID:26538917

  13. Does atraumatic restorative treatment reduce dental anxiety in children? A systematic review and meta-analysis

    PubMed Central

    Simon, Arun K.; Bhumika, T. V.; Nair, N. Sreekumaran

    2015-01-01

    Dental anxiety is one of the major problems affecting children, which impairs the rendering of dental care, leading to impaired quality of life. It often leads to occupational stress in dental personnel and conflict between parents/caregivers. The objective of this study was to conduct a systematic review and meta-analysis of randomized controlled trials done in children, to synthesize evidence of the effectiveness of atraumatic restorative treatment (ART) in reducing dental anxiety in children compared to conventional restorative treatments. The databases searched included PubMed, Google Scholar and The Cochrane Oral Health Group's Trials Register. Eligible studies reporting dental anxiety by a variety of psychometric scales were tabulated. The review was conducted and reported in accordance with the guidelines provided by the Cochrane Collaboration. Among 416 studies retrieved through literature search, six studies matched the inclusion criteria. Due to lack of data, only three studies were included for meta-analysis using RevMan software (Review Manager, Version 5.3;The Cochrane Collaboration, Copenhagen, 2014). The pooled meta-analysis data, (standardized mean difference − 2.12 [95% confidence interval: −4.52, 0.27]) failed to show any difference between ART group and the conventional treatment group. In conclusion, ART was not more beneficial in reducing dental anxiety among pediatric dental patients. The findings are relevant in the field of clinical practice in dentistry in the management of the anxious pediatric dental patient. PMID:26038668

  14. Nanotechnology strategies for antibacterial and remineralizing composites and adhesives to tackle dental caries

    PubMed Central

    Cheng, Lei; Zhang, Ke; Weir, Michael D; Melo, Mary Anne S; Zhou, Xuedong; Xu, Hockin HK

    2015-01-01

    Dental caries is the most widespread disease and an economic burden. Nanotechnology is promising to inhibit caries by controlling biofilm acids and enhancing remineralization. Nanoparticles of silver were incorporated into composites/adhesives, along with quaternary ammonium methacrylates (QAMs), to combat biofilms. Nanoparticles of amorphous calcium phosphate (NACP) released calcium/phosphate ions, remineralized tooth-lesions and neutralized acids. By combining NAg/QAM/NACP, a new class of composites and adhesives with antibacterial and remineralization double benefits was developed. Various other nanoparticles including metal and oxide nanoparticles such as ZnO and TiO2, as well as polyethylenimine nanoparticles and their antibacterial capabilities in dental resins were also reviewed. These nanoparticles are promising for incorporation into dental composites/cements/sealants/bases/liners/adhesives. Therefore, nanotechnology has potential to significantly improve restorative and preventive dentistry. PMID:25723095

  15. Nanotechnology strategies for antibacterial and remineralizing composites and adhesives to tackle dental caries.

    PubMed

    Cheng, Lei; Zhang, Ke; Weir, Michael D; Melo, Mary Anne S; Zhou, Xuedong; Xu, Hockin H K

    2015-03-01

    Dental caries is the most widespread disease and an economic burden. Nanotechnology is promising to inhibit caries by controlling biofilm acids and enhancing remineralization. Nanoparticles of silver were incorporated into composites/adhesives, along with quaternary ammonium methacrylates (QAMs), to combat biofilms. Nanoparticles of amorphous calcium phosphate (NACP) released calcium/phosphate ions, remineralized tooth-lesions and neutralized acids. By combining nanoparticles of silver/QAM/NACP, a new class of composites and adhesives with antibacterial and remineralization double benefits was developed. Various other nanoparticles including metal and oxide nanoparticles such as ZnO and TiO2, as well as polyethylenimine nanoparticles and their antibacterial capabilities in dental resins were also reviewed. These nanoparticles are promising for incorporation into dental composites/cements/sealants/bases/liners/adhesives. Therefore, nanotechnology has potential to significantly improve restorative and preventive dentistry. PMID:25723095

  16. Ultrashort pulse laser processing of hard tissue, dental restoration materials, and biocompatibles

    NASA Astrophysics Data System (ADS)

    Yousif, A.; Strassl, M.; Beer, F.; Verhagen, L.; Wittschier, M.; Wintner, E.

    2007-07-01

    During the last few years, ultra-short laser pulses have proven their potential for application in medical tissue treatment in many ways. In hard tissue ablation, their aptitude for material ablation with negligible collateral damage provides many advantages. Especially teeth representing an anatomically and physiologically very special region with less blood circulation and lower healing rates than other tissues require most careful treatment. Hence, overheating of the pulp and induction of microcracks are some of the most problematic issues in dental preparation. Up till now it was shown by many authors that the application of picosecond or femtosecond pulses allows to perform ablation with very low damaging potential also fitting to the physiological requirements indicated. Beside the short interaction time with the irradiated matter, scanning of the ultra-short pulse trains turned out to be crucial for ablating cavities of the required quality. One main reason for this can be seen in the fact that during scanning the time period between two subsequent pulses incident on the same spot is so much extended that no heat accumulation effects occur and each pulse can be treated as a first one with respect to its local impact. Extension of this advantageous technique to biocompatible materials, i.e. in this case dental restoration materials and titanium plasma-sprayed implants, is just a matter of consequence. Recently published results on composites fit well with earlier data on dental hard tissue. In case of plaque which has to be removed from implants, it turns out that removal of at least the calcified version is harder than tissue removal. Therefore, besides ultra-short lasers, also Diode and Neodymium lasers, in cw and pulsed modes, have been studied with respect to plaque removal and sterilization. The temperature increase during laser exposure has been experimentally evaluated in parallel.

  17. Esthetic integration between ceramic veneers and composite restorations: a case report

    PubMed Central

    Farronato, Davide; Mangano, Francesco; Pieroni, Stefano; Giudice, Giuseppe Lo; Briguglio, Roberto; Briguglio, Francesco

    2012-01-01

    Summary The tooth structure preservation is the best way to postpone more invasive therapies. Especially in young patients more conservative techniques should be applied. Bonded porcelain veneers and even more the direct composite restorations, are the two therapeutic procedures that require the fewer sacrifice of dental tissue, finalized to the optimal recovery of aesthetic and functional outcome. Although the two techniques require different methods and materials, is possible to achieve a correct integration of both the methods by some technical and procedural measures. In the presented case is planned a rehabilitation of the four upper incisors by ceramic veneers and direct composite restorations. Care is taken for the surface treatment of ceramic restorations, with the objective of achieving integration, not only between natural teeth and restorations, but also between the different materials in use. The purpose of this article is to show how a proper design of the treatment plan leads to obtain predictable results with both direct and indirect techniques. PMID:23386935

  18. Understanding dental CAD/CAM for restorations--accuracy from a mechanical engineering viewpoint.

    PubMed

    Tapie, Laurent; Lebon, Nicolas; Mawussi, Bernardin; Fron-Chabouis, Hélène; Duret, Francois; Attal, Jean-Pierre

    2015-01-01

    As is the case in the field of medicine, as well as in most areas of daily life, digital technology is increasingly being introduced into dental practice. Computer-aided design/ computer-aided manufacturing (CAD/CAM) solutions are available not only for chairside practice but also for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental practice can be considered as the handling of devices and software processing for the almost automatic design and creation of dental restorations. However, dentists who want to use dental CAD/CAM systems often do not have enough information to understand the variations offered by such technology practice. Knowledge of the random and systematic errors in accuracy with CAD/CAM systems can help to achieve successful restorations with this technology, and help with the purchasing of a CAD/CAM system that meets the clinical needs of restoration. This article provides a mechanical engineering viewpoint of the accuracy of CAD/ CAM systems, to help dentists understand the impact of this technology on restoration accuracy. PMID:26734668

  19. Polymerization shrinkage of a dental resin composite determined by a fiber optic Fizeau interferometer

    NASA Astrophysics Data System (ADS)

    Arenas, Gustavo; Noriega, Sergio; Vallo, Claudia; Duchowicz, Ricardo

    2007-03-01

    A fiber optic sensing method based on a Fizeau-type interferometric scheme was employed for monitoring linear polymerization shrinkage in dental restoratives. This technique offers several advantages over the conventional methods of measuring polymerization contraction. This simple, compact, non-invasive and self-calibrating system competes with both conventional and other high-resolution bulk interferometric techniques. In this work, an analysis of the quality of interference signal and fringes visibility was performed in order to characterize their resolution and application range. The measurements of percent linear contraction as a function of the sample thickness were carried out in this study on two dental composites: Filtek P60 (3M ESPE) Posterior Restorer and Filtek Z250 (3M ESPE) Universal Restorer. The results were discussed with respect to others obtained employing alternative techniques.

  20. Benchmarking matching color in composite restorations

    PubMed Central

    Migliau, Guido; Piccoli, Luca; Besharat, Laith Konstantinos; Romeo, Umberto

    2016-01-01

    Summary The purpose of this study was to investigate the color samples (A2, A3 and B1) of three different brands of resin composites using dentine masses. 135 discs were prepared (5 plates for each thickness, color and brand of composite material). A colorimetric evaluation, using white and black background, was performed just after preparation. The color was measured corresponding to “Vita” scale and ΔL, Δa, Δb and ΔE values were calculated using a spectrophotometer. The results showed that Value, Chroma and Hue often differ even if the same commercial color and same thickness is used. In conclusion, this study showed that the perfect aesthetics restoration is possible combining individual abilities, experience and correct techniques. PMID:27512531

  1. Benchmarking matching color in composite restorations.

    PubMed

    Migliau, Guido; Piccoli, Luca; Besharat, Laith Konstantinos; Romeo, Umberto

    2016-01-01

    The purpose of this study was to investigate the color samples (A2, A3 and B1) of three different brands of resin composites using dentine masses. 135 discs were prepared (5 plates for each thickness, color and brand of composite material). A colorimetric evaluation, using white and black background, was performed just after preparation. The color was measured corresponding to "Vita" scale and ΔL, Δa, Δb and ΔE values were calculated using a spectrophotometer. The results showed that Value, Chroma and Hue often differ even if the same commercial color and same thickness is used. In conclusion, this study showed that the perfect aesthetics restoration is possible combining individual abilities, experience and correct techniques. PMID:27512531

  2. Optical properties of dental restorative materials in the wavelength range 400 to 700 nm for the simulation of color perception

    NASA Astrophysics Data System (ADS)

    Friebel, Moritz; Povel, Kirsten; Cappius, Hans-Joachim; Helfmann, Jürgen; Meinke, Martina

    2009-09-01

    Aesthetic restorations require dental restorative materials to have optical properties very similar to those of the teeth. A method is developed to this end to determine the optical parameters absorption coefficient μa, scattering coefficient μs, anisotropy factor g, and effective scattering coefficient μs' of dental restorative materials. The method includes sample preparation and measurements of transmittance and reflectance in an integrating sphere spectrometer followed by inverse Monte Carlo simulations. Using this method the intrinsic optical parameters are determined for shade B2 of the light-activated composites TPH® Spectrum®, Esthet-X®, and the Ormocer® Definite® in the wavelength range 400 to 700 nm. By using the determined parameters μa, μs, and g together with an appropriate phase function, the reflectance of samples with 1-mm layer thickness and shade B2 could be predicted with a very high degree of accuracy using a forward Monte Carlo simulation. The color perception was calculated from the simulated reflectance according to the CIELAB system. We initiate the compilation of a data pool of optical parameters that in the future will enable calculation models to be used as a basis for optimization of the optical approximation of the natural tooth, and the composition of new materials and their production process.

  3. New restoration and direct pulp capping systems using adhesive composite resin.

    PubMed

    Kashiwada, T; Takagi, M

    1991-12-01

    There have been many arguments on the irritating mechanisms of the composite resin on the dental pulp. While the direct irritative effect of the resin has been preferred, some authors considered that the marginal microleakage and the resulting bacterial infection play a more important role in inducing the complicating pulp irritation. We developed a new filling technique, called the direct inlay restoration method, which could prevent the marginal leakage associated with the polymerization shrinkage of the adhesive composite resin. In this study, we tried to apply our method clinically. None of the 440 cases which were filled with the adhesive composite resin and 60 cases out of 64 cases in which the pulps were directly capped with the adhesive composite resin developed any signs and symptoms of pulp irritation. The other 4 cases developed signs of pulp irritation. Two of those 4 cases were pulpectomized due to spontaneous pain and the other 2 cases turned out to be well after re-restoration. With the informed consent of the patients, the direct pulp capping using the adhesive composite resin was experimentally performed on 6 caries-free 3rd molars and the histopathological examination of these capped molars revealed that neither significant degenerative nor inflammatory changes were brought about in the dental pulp. These clinical and histopathological observation suggest that the dental pulp irritation after resin filling is not induced by the composite resin itself. PMID:1764760

  4. Comparison of wear and clinical performance between amalgam, composite and open sandwich restorations: 2-year results.

    PubMed

    Sachdeo, A; Gray, Gordon B; Sulieman, M A; Jagger, Daryll C

    2004-03-01

    There has been some disquiet over the use of mercury containing restorative materials. The most commonly used alternative is composite resin but this has the potential disadvantage associated with wear and marginal leakage, which in turn, has proven to result in secondary caries and sensitivity. To overcome the shortcomings of a directly placed composite restoration, the glass-ionomer/composite open sandwich technique was introduced followed by the subsequent introduction of compomer systems. The aims of this study were to evaluate the wear and clinical performance of a control group of amalgam restorations compared with that of a group of posterior composite resin restorations fillings and a group of compomer/composite open sandwich restorations placed by a single general dental practitioner. The duration of the study was 2 years. One hundred and thirty three (71.4%) patients were successfully recalled and the wear and clinical performance of each restoration after 6, 12 and 24 months was measured, indirectly. There was no statistically significant difference recorded between the groups at 6 months or 1 year (p > 0.05). However, at the end of the 2-year study, there was a significantly lower rate of wear recorded for the control amalgam restorations compared with other two groups (p = 0.033). There was no statistically significant difference in wear recorded between the two groups of tooth-coloured restorations (p > 0.05). With regards to clinical performance of the restorations, occlusal and proximal contacts in each group of restoration remained satisfactory throughout the study. PMID:15058177

  5. Development of novel self-healing and antibacterial dental composite containing calcium phosphate nanoparticles

    PubMed Central

    Wu, Junling; Weir, Michael D.; Melo, Mary Anne S.; Xu, Hockin H. K.

    2015-01-01

    Objectives Fracture and secondary caries are the primary reasons for dental restoration failure. The objective of this study was to develop a self-healing composite to heal cracks, while containing dimethylaminohexadecyl methacrylate (DMAHDM) for antibacterial function and nanoparticles of amorphous calcium phosphate (NACP) for remineralization. Methods Microcapsules were synthesized with poly(urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid. Composite contained 20 mass% of NACP and 35% glass fillers. In addition, composite contained 0%, 2.5%, 5%, 7.5%, or 10% of microcapsules. A single edge V-notched beam method measured fracture toughness (KIC) and self-healing efficiency. A dental plaque microcosm biofilm model was used to test the antibacterial properties. Results Incorporation of microcapsules up to 7.5% into the composite did not adversely affect the mechanical properties (p > 0.1). Successful self-healing was achieved, with KIC recovery of 65–81% (mean ± sd; n = 6) to regain the load-bearing capability after composite fracture. The self-healing DMAHDM-NACP composite displayed a strong antibacterial potency, inhibiting biofilm viability and lactic acid production, and reducing colony-forming units by 3–4 orders of magnitude, compared to control composite without DMAHDM. Conclusions A dental composite was developed with triple benefits of self-healing after fracture, antibacterial activity, and remineralization capability for the first time. Clinical significance The self-healing, antibacterial and remineralizing composite may be promising for tooth cavity restorations to combat bulk fracture and secondary caries. The method of using triple agents (self-healing microcapsules, DMAHDM, and NACP) may have wide applicability to other dental composites, adhesives, sealants and cements. PMID:25625674

  6. Mini fiberglass post for composite resin restorations: A clinical report.

    PubMed

    Morgan, Luís Fernando Dos Santos Alves; Martins, Adriana Vieira; Albuquerque, Rodrigo de Castro; Silveira, Rodrigo Richard; Silva, Nelson Renato França Alves; Moreira, Allysson Nogueira

    2016-06-01

    Threaded metal pins have been used to create additional retention for large composite resin restorations. However, their dark appearance may compromise esthetic outcome. The use of small fiberglass posts has been advocated as an alternative. This clinical report describes a mini fiberglass post (MFP) used to provide additional retention in a fractured anterior tooth that received a composite resin restoration. The MFP represents a promising option for creating additional retention for large composite resin restorations. PMID:26724848

  7. Inequalities in preventive and restorative dental services in England, Wales and Northern Ireland.

    PubMed

    Cheema, J; Sabbah, W

    2016-09-01

    Aims The objective of this study is to assess socioeconomic inequalities in the use of selected dental procedures.Methods Data is from the Adult Dental Health Survey 2009, a nationally representative cross-sectional survey of England, Northern Ireland and Wales. Overall, 6,279 participants were included in the analysis. Occupational classification and education were used to assess variations in the use of preventive, restorative services and tooth extraction using a series of logistic regression models, adjusting for age, sex, ethnicity, DMFT, self-reported oral health, dental visits and country.Results There were clear socioeconomic variations in the utilisation of preventive and restorative services. In the fully adjusted model those with no educational qualification were less likely to report ever having preventive services than those with a degree (OR 0.48, 95%CI: 0.36,0.65). Similarly, individuals in routine/manual occupation were significantly less likely to report ever having preventive services than those in managerial/professional occupation (OR 0.58, 95%CI: 0.46,0.74) in the fully adjusted model.Conclusion The findings imply that despite relatively equitable access and higher use of dental services in UK, the least educated and those at the bottom of social hierarchy are less likely to have preventive and restorative dental services. PMID:27608576

  8. Genotoxicity evaluation of dental restoration nanocomposite using comet assay and chromosome aberration test

    NASA Astrophysics Data System (ADS)

    Musa, Marahaini; Thirumulu Ponnuraj, Kannan; Mohamad, Dasmawati; Rahman, Ismail Ab

    2013-01-01

    Nanocomposite is used as a dental filling to restore the affected tooth, especially in dental caries. The dental nanocomposite (KelFil) for tooth restoration used in this study was produced by the School of Dental Sciences, Universiti Sains Malaysia, Malaysia and is incorporated with monodispersed, spherical nanosilica fillers. The aim of the study was to determine the genotoxic effect of KelFil using in vitro genotoxicity tests. The cytotoxicity and genotoxicity of KelFil was evaluated using MTT assay, comet assay and chromosome aberration tests with or without the addition of a metabolic activation system (S9 mix), using the human lung fibroblast cell line (MRC-5). Concurrent negative and positive controls were included. In the comet assay, no comet formation was found in the KelFil groups. There was a significant difference in tail moment between KelFil groups and positive control (p < 0.05). Similarly, no significant aberrations in chromosomes were noticed in KelFil groups. The mitotic indices of treatment groups and negative control were significantly different from positive controls. Hence, it can be concluded that the locally produced dental restoration nanocomposite (KelFil) is non-genotoxic under the present test conditions.

  9. Microgaps and Demineralization Progress around Composite Restorations.

    PubMed

    Turkistani, A; Nakashima, S; Shimada, Y; Tagami, J; Sadr, A

    2015-08-01

    This study investigated the influence of adhesives and marginal sealing on demineralization progress using optical coherence tomography (OCT). Cavities (4 × 2 mm) were prepared in bovine incisors and restored using Clearfil SE Protect (SP), Bond Force (BF), Scotchbond Universal (SB), or G-Bond Plus (GB), followed by Estelite Flow Quick flowable composite. The control group received no adhesive (n = 10). After 3-d incubation in artificial saliva and 10,000 thermal cycles, gaps at enamel and dentin margins were measured at 8 locations on cross-sectional images obtained from each restoration using swept-source OCT at 1310-nm wavelength. Specimens were demineralized using acidified gel (pH = 4.5) for 5 wk and scanned every week to monitor the lesion progress at the same marginal locations. Repeated-measures analysis of variance showed that demineralization period and adhesive type and their interaction had a significant effect on the lesion size in both substrates (P < 0.001). SP, BF, and SB had significantly lower enamel and dentin initial gaps than the control and GB (P < 0.05). Enamel lesion progress was slower in the fluoride-releasing adhesives SP and BF and significantly different from SB, GB, and the control (P < 0.001). SP and BF dentin lesions were significantly different from GB and the control (P < 0.001), but not from SB (P > 0.05). A significant positive correlation (P < 0.05) was found between initial gap length and formed lesion size in both substrates, which was stronger in enamel (r = 0.63) than dentin (r = 0.35). Microgaps forming at the margins of restorations depend on adhesives and significantly contribute to the progress of demineralization around the margins, while fluoride release may decrease the rate of progression. PMID:26082389

  10. [The atraumatic restorative treatment approach in pediatric dental care: a comparative clinical study].

    PubMed

    Dmitrova, A G; Kulakov, A A

    2015-01-01

    The aim of this study was to assess and compare the discomfort levels during Atraumatic Restorative Treatment and Minimal Cavity Preparation using rotary instruments and Air abrasion method. The results of the study suggest that ART induces less discomfort, therefore this method can be recommended for children who have a fear of dental procedures as well as for children with intellectual disabilities. PMID:26145474

  11. Quantification of Staphylococcus aureus adhesion forces on various dental restorative materials using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Merghni, Abderrahmen; Kammoun, Dorra; Hentati, Hajer; Janel, Sébastien; Popoff, Michka; Lafont, Frank; Aouni, Mahjoub; Mastouri, Maha

    2016-08-01

    In the oral cavity dental restorative biomaterials can act as a reservoir for infection with opportunistic Staphylococcus aureus pathogen, which can lead to the occurrence of secondary caries and treatment failures. Our aim was to evaluate the adhesion forces by S. aureus on four dental restorative biomaterials and to correlate this finding to differences in specific surface characteristics. Additionally, the influence of salivary conditioning films in exerted adhesion forces was investigated. The substrate hydrophobicity was measured by goniometer and the surface free energy was calculated using the equilibrium advancing contact angle values of water, formamide, and diiodomethane on the tested surfaces. The surface roughness was determined using atomic force microscope (AFM). Additionally, cell force spectroscopy was achieved to quantify the forces that drive cell-substrate interactions. S. aureus bacterium exerted a considerable adhesion forces on various dental restorative materials, which decreased in the presence of saliva conditioning film. The influence of the surface roughness and free energy in initial adhesion appears to be more important than the effect of hydrophobicity, either in presence or absence of saliva coating. Hence, control of surface properties of dental restorative biomaterials is of crucial importance in preventing the attachment and subsequent the biofilm formation.

  12. Perception of dental esthetics: influence of restoration type, symmetry, and color in four different countries.

    PubMed

    Mehl, Christian; Harder, Sönke; Lin, Jun; Vollrath, Oliver; Kern, Matthias

    2015-01-01

    In this study, the influence of restoration type, symmetry, and color on the perception of dental appearance was evaluated. An esthetic questionnaire was completed by 29 patients before and after esthetic rehabilitation. In addition, 94 dentists from four countries (Germany, the United Kingdom [UK], China, and Switzerland) evaluated the influence of the above factors using before-and-after rehabilitation pictures. The most invasive treatment was recommended by Chinese dentists, while German, Swiss, and UK dentists recommended comparable treatment options. As for restorative symmetry, restoration type, and color, significant differences could be found among and within the dentists of the four countries (P ± .05). PMID:25588175

  13. 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.

  14. Establishing gingival symmetry when placing anterior direct nanohybrid composite restorations.

    PubMed

    Hollar, Susan

    2013-01-01

    Restoring the beauty of patients' smiles requires clinicians to incorporate both tooth and gingival esthetics. When gingivectomies and crown-lengthening procedures are required, opting for direct nanohybrid composite restorations can help enable dentists to achieve harmonious blending of the gingival architecture and the anticipated restoration by allowing for tissue healing and subsequent modifications to the gingival portions of restorations. This article presents two cases in which anterior nanohybrid direct composite restorations provided a means to enhance tooth esthetics simultaneous to improving gingival harmony. PMID:24568218

  15. Mechanical benefits of conservative restoration for dental fissure caries.

    PubMed

    Zhang, Zhongpu; Zheng, Keke; Li, Eric; Li, Wei; Li, Qing; Swain, Michael V

    2016-01-01

    The principle of minimal intervention dentistry (MID) is to limit removal of carious tooth tissue while maximizing its repair and survival potential. The objective of this study is to explore the fracture resistance of a permanent molar tooth with a fissure carious lesion along with three clinical restoration procedures, namely one traditional and two conservative approaches, based upon MID. The traditional restoration employs extensive surgical removal of enamel and dentine about the cavity to eliminate potential risk of further caries development, while conservative method #1 removes significantly less enamel and infected dentine, and conservative method #2 only restores the overhanging enamel above the cavity and leaves the infected and affected dentine as it was. An extended finite element method (XFEM) is adopted here to analyze the fracture behaviors of both two-dimensional (2D) and three-dimensional (3D) modeling of these four different scenarios. It was found that the two conservative methods exhibited better fracture resistance than the traditional restorative method. Although conservative method #2 has less fracture resistance than method #1, it had significantly superior fracture resistance compared to other restorations. More important, after cavity sealing it may potentially enhance the opportunity for remineralization and improved loading bearing capacity and fracture resistance. PMID:26298801

  16. CHIPPING FRACTURE RESISTANCE OF DENTAL CAD/CAM RESTORATIVE MATERIALS: PART I, PROCEDURES AND RESULTS

    PubMed Central

    Quinn, G. D.; Giuseppetti, A. A.; Hoffman, K. H.

    2014-01-01

    Objective The edge chipping test was used to measure the fracture resistance of CAD/CAM dental restoration ceramics and resin composites. Methods An edge chipping machine was used to evaluate six materials including one feldspathic porcelain, two glass ceramics, a filled resin-composite, a yttria-stabilized zirconia, and a new ceramic-resin composite material. Force versus edge distance data were collected over a broad range of forces and distances. Data were analyzed by several approaches and several chipping resistance parameters were evaluated. The effects of using different indenter types were explored. Results The force versus distance trends were usually nonlinear with good fits to a power law equation with exponents usually ranging from 1.2 to 1.9. The order of chipping resistance (from least to greatest) was: feldspathic porcelain and a leucite glass ceramic (which were similar), followed by the lithium disilicate glass ceramic and the two resin composites (which were similar), and finally the zirconia which had the greatest resistance to chipping. Chipping with a Vickers indenter required 28% to 45% more force than with the sharp conical 120° indenter. The two indenters rank materials approximately the same way. The power law exponents were very similar for the two indenters for a particular material, but the exponents varied with material. The Rockwell C indenter gives different power law trends and rankings. Significance Despite the variations in the trends and indenters, simple comparisons between materials can be made by chipping with sharp conical 120° or Vickers indenters at 0.50 mm. Broad distance ranges are recommended for trend evaluation. PMID:24685178

  17. A novel protein-repellent dental composite containing 2-methacryloyloxyethyl phosphorylcholine

    PubMed Central

    Zhang, Ning; Chen, Chen; Melo, Mary AS; Bai, Yu-Xing; Cheng, Lei; Xu, Hockin HK

    2015-01-01

    Secondary caries due to biofilm acids is a primary cause of dental composite restoration failure. To date, there have been no reports of dental composites that can repel protein adsorption and inhibit bacteria attachment. The objectives of this study were to develop a protein-repellent dental composite by incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) and to investigate for the first time the effects of MPC mass fraction on protein adsorption, bacteria attachment, biofilm growth, and mechanical properties. Composites were synthesized with 0 (control), 0.75%, 1.5%, 2.25%, 3%, 4.5% and 6% of MPC by mass. A commercial composite was also tested as a control. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composite was determined by the microbicinchoninic acid method. A human saliva microcosm biofilm model was used. Early attachment at 4 h, biofilm at 2 days, live/dead staining and colony-forming units (CFUs) of biofilms grown on the composites were investigated. Composites with MPC of up to 3% had mechanical properties similar to those without MPC and those of the commercial control, whereas 4.5% and 6% MPC decreased the mechanical properties (P<0.05). Increasing MPC from 0 to 3% reduced the protein adsorption on composites (P<0.05). The composite with 3% MPC had protein adsorption that was 1/12 that of the control (P<0.05). Oral bacteria early attachment and biofilm growth were also greatly reduced on the composite with 3% MPC, compared to the control (P<0.05). In conclusion, incorporation of MPC into composites at 3% greatly reduced protein adsorption, bacteria attachment and biofilm CFUs, without compromising mechanical properties. Protein-repellent composites could help to repel bacteria attachment and plaque build-up to reduce secondary caries. The protein-repellent method might be applicable to other dental materials. PMID:25655010

  18. Protein-repellent and antibacterial dental composite to inhibit biofilms and caries

    PubMed Central

    Zhang, Ning; Ma, Jianfeng; Melo, Mary A. S.; Weir, Michael D.; Bai, Yuxing; Xu, Hockin H. K.

    2015-01-01

    Objectives Biofilm acids contribute to secondary caries, which is a main reason for dental restoration failures. The objectives of this study were to: (1) develop a protein-repellent and antibacterial composite, and (2) investigate the effects of combining 2-methacryloyloxyethyl phosphorylcholine (MPC) with quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM) on composite mechanical properties and biofilm response for the first time. Methods MPC, DMAHDM and glass particles were mixed into a dental resin composite. Mechanical properties were measured in three-point flexure. Protein adsorption onto the composites was measured by a micro bicinchoninic acid method. A human saliva microcosm model was used to grow biofilms on composites. Colony-forming unit (CFU) counts, live/dead assay, metabolic activity, and lactic acid production of biofilms were determined. Results Incorporation of 3% MPC and 1.5% DMAHDM into composite achieved protein-repellent and antibacterial capabilities without compromising the mechanical properties. Composite with 3% MPC + 1.5% DMAHDM had protein adsorption that was 1/10 that of a commercial composite (p < 0.05). The composite with 3% MPC + 1.5% DMAHDM had much greater reduction in biofilm growth than using MPC or DMAHDM alone (p < 0.05). Biofilm CFU counts on composite with 3% MPC + 1.5% DMAHDM were more than three orders of magnitude lower than that of commercial control. Conclusions Dental composite with a combination of strong protein-repellent and antibacterial capabilities was developed for the first time. Composite with MPC and DMAHDM greatly reduced biofilm activity and is promising to inhibit secondary caries. The dual agents of MPC plus DMAHDM may have wide applicability to other dental materials. PMID:25478889

  19. Combined effect of staining substances on the discoloration of esthetic Class V dental restorative materials.

    PubMed

    Lee, Yong-Keun; Powers, John M

    2007-01-01

    The purpose of this study was to determine the combined effect of an organic substance (mucin as a substitute for salivary organic substances), chlorhexidine, and an iron compound/tea solution on the changes in the color of esthetic Class V dental restorative materials. Color of a glass ionomer, resin-modified glass ionomer, compomer and flowable resin composite of A2 shade, respectively, was determined according to the CIELAB color scale relative to the standard illuminant D65. Color was measured at baseline, and after sequential immersion in the following substances: Step-1, mucin in PBS (MCP) for 48 h; Step-2, chlorhexidine (CHX) for 24 h; Step-3, iron compound (IRN) or tea solution (TEA) up to 7 days; and Step-4, ultrasonic cleaning for 1 h. Color change (DeltaE(ab )*) was calculated by the equation: DeltaE(ab)* = [(DeltaL*)(2) + (Deltaa*)(2) + (Deltab*)(2)](1/2), of which DeltaL(*) indicates changes in value, Deltaa(*) indicates changes in red-green parameter and Deltab(*) indicates changes in yellow-blue parameter. DeltaE(ab)* values after immersion in MCP and CHX were compared, and DeltaE(ab)* values after immersion in IRN or TEA, and subsequent ultrasonic cleaning were compared with respect to the restorative material and immersion substance. DeltaE(ab)* and changes in the color parameters (DeltaL(*), DeltaC(ab)* and DeltaH(ab)*) were analyzed by repeated measures, analysis of variance and a post-hoc test at the 0.05 level of significance. Color changes after immersion in MCP were acceptable (DeltaE(ab)* < 3.3), and those after immersion in CHX were generally acceptable. The range of DeltaE(ab)* values after immersion in IRN was 3.1-19.6, and that after ultrasonic cleaning was 2.4-9.6. The range of DeltaE(ab)* values after immersion in TEA was 10.7-21.1, and that after ultrasonic cleaning was 11.9-14.5. Color changes of four Class V restorative materials after combined treatment with mucin, chlorhexidine and an iron compound/tea solution were not acceptable

  20. Determination of optical properties in dental restorative biomaterials using the inverse-adding-doubling method

    NASA Astrophysics Data System (ADS)

    Fernández-Oliveras, Alicia; Rubiño, Manuel; Pérez, María. M.

    2013-11-01

    Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function, the refractive index, and the surface conditions (roughness). By means of the inverse-adding-doubling (IAD) method, transmittance and reflectance measurements lead to the determination of the absorption coefficient and the reduced scattering coefficient. The additional measurement of the phase function performed by goniometry allows the separation of the reduced scattering coefficient into the scattering coefficient and the scattering anisotropy factor. The majority of techniques, such as the one utilized in this work, involve the use of integrating spheres to measure total transmission and reflection. We have employed an integrating sphere setup to measure the total transmittance and reflectance of dental biomaterials used in restorative dentistry. Dental biomaterials are meant to replace dental tissues, such as enamel and dentine, in irreversibly diseased teeth. In previous works we performed goniometric measurements in order to evaluate the scattering anisotropy factor for these kinds of materials. In the present work we have used the IAD method to combine the measurements performed using the integrating sphere setup with the results of the previous goniometric measurements. The aim was to optically characterize the dental biomaterials analyzed, since whole studies to assess the appropriate material properties are required in medical applications. In this context, complete optical characterizations play an important role in achieving the fulfillment of optimal quality and the final success of dental biomaterials used in restorative dentistry.

  1. Composition of Mineral Produced by Dental Mesenchymal Stem Cells

    PubMed Central

    Volponi, A.A.; Gentleman, E.; Fatscher, R.; Pang, Y.W.Y.; Gentleman, M.M.; Sharpe, P.T.

    2015-01-01

    Mesenchymal stem cells isolated from different dental tissues have been described to have osteogenic/odontogenic-like differentiation capacity, but little attention has been paid to the biochemical composition of the material that each produces. Here, we used Raman spectroscopy to analyze the mineralized materials produced in vitro by different dental cell populations, and we compared them with the biochemical composition of native dental tissues. We show that different dental stem cell populations produce materials that differ in their mineral and matrix composition and that these differ from those of native dental tissues. In vitro, BCMP (bone chip mass population), SCAP (stem cells from apical papilla), and SHED (stem cells from human-exfoliated deciduous teeth) cells produce a more highly mineralized matrix when compared with that produced by PDL (periodontal ligament), DPA (dental pulp adult), and GF (gingival fibroblast) cells. Principal component analyses of Raman spectra further demonstrated that the crystallinity and carbonate substitution environments in the material produced by each cell type varied, with DPA cells, for example, producing a more carbonate-substituted mineral and with SCAP, SHED, and GF cells creating a less crystalline material when compared with other dental stem cells and native tissues. These variations in mineral composition reveal intrinsic differences in the various cell populations, which may in turn affect their specific clinical applications. PMID:26253190

  2. Synthesis and characterization of antibacterial dental monomers and composites

    PubMed Central

    Xu, Xiaoming; Wang, Yapin; Liao, Sumei; Wen, Zezhang T.; Fan, Yuwei

    2012-01-01

    The objective of this study is to synthesize antibacterial methacrylate and methacrylamide monomers and formulate antibacterial fluoride-releasing dental composites. Three antibacterial methacrylate or methacrylamide monomers containing long-chain quaternary ammonium fluoride, 1,2-methacrylamido-N,N,N-trimethyldodecan-1-aminium fluoride (monomer I), N-benzyl-11-(methacryloyloxy)-N,N-dimethylundecan-1-aminium fluoride (monomer II), and methacryloxyldecylpyridinium fluoride (monomer III) have been synthesized and analyzed by nuclear magnetic resonance (NMR) and mass spectrometry (MS). The cytotoxicity test and bactericidal test against Streptococcus mutans indicate that antibacterial monomer II is superior to monomers I and III. A series of dental composites containing 0–6% of antibacterial monomer II have been formulated and tested for degree of conversion (DC), flexure strength, water sorption, solubility, and inhibition of S. mutans biofilms. An antibacterial fluoride-releasing dental composite has also been formulated and tested for flexure strength and fluoride release. The dental composite containing 3% of monomer II has a significant effect against S. mutans biofilm formation without major adverse effects on its physical and mechanical properties. The new antibacterial monomers can be used together with the fluoride-releasing monomers containing a ternary zirconiun- fluoride chelate to formulate a new antibacterial fluoride- releasing dental composite. Such a new dental composite is expected to have higher anticaries efficacy and longer service life. PMID:22447582

  3. Dental practitioners' attitudes, subjective norms and intentions to practice atraumatic restorative treatment (ART) in Tanzania.

    PubMed

    Kikwilu, Emil N; Frencken, Jo E; Mulder, Jan; Masalu, Joyce R

    2009-01-01

    The aim of this study was to describe the attitude and subjective norm of dental practitioners towards practicing the atraumatic restorative treatment (ART) in Tanzania. A pre-tested questionnaire on attitudes and subjective norms to practice ART was mailed to all 147 dental practitioners working in the regional and district government clinics. The independent variables were: gender, working experience, qualification and ever heard of ART. The dependent variables were: attitude, subjective norm and intention to practice ART. Chi-square tests and multiple regression analysis were used to test for effects between independent and dependent variables. Significance level was set at 5%. A total of 138 practitioners returned completed questionnaires. More experienced dental practitioners encountered moderate social pressure than less experienced dental practitioners, who met strong social pressure (p=0.045). A total of 73.2% of dental practitioners felt that ART was worth introducing in Tanzania, 92.8% recommended ART training for all dental practitioners and 97.8% recommended inclusion of ART in dental curricula. Positive attitude, strong subjective norm and high intention to practice ART were recorded in 76.3%, 28.1% and 90.6% of the practitioners, respectively. Only subjective norm had a statistically significant influence on the intention to practice ART (p<0.0001). The results indicated that dental practitioners were willing to have ART introduced in Tanzania and had positive attitudes towards practicing this technique. Nevertheless, their intention to perform ART was strongly influenced by social pressures. Therefore, in order to have a successful introduction of ART in Tanzania, people who matter in the daily practice of dental practitioners need to accept and appraise the ART approach positively. PMID:19274393

  4. Molecular Toxicology of Substances Released from Resin–Based Dental Restorative Materials

    PubMed Central

    Bakopoulou, Athina; Papadopoulos, Triantafillos; Garefis, Pavlos

    2009-01-01

    Resin-based dental restorative materials are extensively used today in dentistry. However, significant concerns still remain regarding their biocompatibility. For this reason, significant scientific effort has been focused on the determination of the molecular toxicology of substances released by these biomaterials, using several tools for risk assessment, including exposure assessment, hazard identification and dose-response analysis. These studies have shown that substances released by these materials can cause significant cytotoxic and genotoxic effects, leading to irreversible disturbance of basic cellular functions. The aim of this article is to review current knowledge related to dental composites’ molecular toxicology and to give implications for possible improvements concerning their biocompatibility. PMID:19865523

  5. Modelling the Longevity of Dental Restorations by means of a CBR System

    PubMed Central

    Aliaga, Ignacio J.; Vera, Vicente; García, Alvaro E.

    2015-01-01

    The lifespan of dental restorations is limited. Longevity depends on the material used and the different characteristics of the dental piece. However, it is not always the case that the best and longest lasting material is used since patients may prefer different treatments according to how noticeable the material is. Over the last 100 years, the most commonly used material has been silver amalgam, which, while very durable, is somewhat aesthetically displeasing. Our study is based on the collection of data from the charts, notes, and radiographic information of restorative treatments performed by Dr. Vera in 1993, the analysis of the information by computer artificial intelligence to determine the most appropriate restoration, and the monitoring of the evolution of the dental restoration. The data will be treated confidentially according to the Organic Law 15/1999 on 13 December on the Protection of Personal Data. This paper also presents a clustering technique capable of identifying the most significant cases with which to instantiate the case-base. In order to classify the cases, a mixture of experts is used which incorporates a Bayesian network and a multilayer perceptron; the combination of both classifiers is performed with a neural network. PMID:25866792

  6. Optical characterization of one dental composite resin using bovine enamel as reinforcing filler

    NASA Astrophysics Data System (ADS)

    Tribioli, J. T.; Jacomassi, D.; Rastelli, A. N. S.; Pratavieira, S.; Bagnato, V. S.; Kurachi, C.

    2012-01-01

    The use of composite resins for restorative procedure in anterior and posterior cavities is highly common in Dentistry due to its mechanical and aesthetic properties that are compatible with the remaining dental structure. Thus, the aim of this study was to evaluate the optical characterization of one dental composite resin using bovine enamel as reinforcing filler. The same organic matrix of the commercially available resins was used for this experimental resin. The reinforcing filler was obtained after the gridding of bovine enamel fragments and a superficial treatment was performed to allow the adhesion of the filler particles with the organic matrix. Different optical images as fluorescence and reflectance were performed to compare the experimental composite with the human teeth. The present experimental resin shows similar optical properties compared with human teeth.

  7. New layer-based imaging and rapid prototyping techniques for computer-aided design and manufacture of custom dental restoration.

    PubMed

    Lee, M-Y; Chang, C-C; Ku, Y C

    2008-01-01

    Fixed dental restoration by conventional methods greatly relies on the skill and experience of the dental technician. The quality and accuracy of the final product depends mostly on the technician's subjective judgment. In addition, the traditional manual operation involves many complex procedures, and is a time-consuming and labour-intensive job. Most importantly, no quantitative design and manufacturing information is preserved for future retrieval. In this paper, a new device for scanning the dental profile and reconstructing 3D digital information of a dental model based on a layer-based imaging technique, called abrasive computer tomography (ACT) was designed in-house and proposed for the design of custom dental restoration. The fixed partial dental restoration was then produced by rapid prototyping (RP) and computer numerical control (CNC) machining methods based on the ACT scanned digital information. A force feedback sculptor (FreeForm system, Sensible Technologies, Inc., Cambridge MA, USA), which comprises 3D Touch technology, was applied to modify the morphology and design of the fixed dental restoration. In addition, a comparison of conventional manual operation and digital manufacture using both RP and CNC machining technologies for fixed dental restoration production is presented. Finally, a digital custom fixed restoration manufacturing protocol integrating proposed layer-based dental profile scanning, computer-aided design, 3D force feedback feature modification and advanced fixed restoration manufacturing techniques is illustrated. The proposed method provides solid evidence that computer-aided design and manufacturing technologies may become a new avenue for custom-made fixed restoration design, analysis, and production in the 21st century. PMID:18183523

  8. Shrinkage of dental composite in simulated cavity measured with digital image correlation.

    PubMed

    Li, Jianying; Thakur, Preetanjali; Fok, Alex S L

    2014-01-01

    Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage. Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions. The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the "tooth-restoration" interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material. PMID:25079865

  9. Novel Dental Restorative Materials having Low Polymerization Shrinkage Stress via Stress Relaxation by Addition-Fragmentation Chain Transfer

    PubMed Central

    Park, Hee Young; Kloxin, Christopher J.; Abuelyaman, Ahmed S.; Oxman, Joe D.; Bowman, Christopher N.

    2012-01-01

    Objectives To produce a reduced stress dental restorative material while simultaneously maintaining excellent mechanical properties, we have incorporated an allyl sulfide functional group into norbornene-methacrylate comonomer resins. We hypothesize that the addition-fragmentation chain transfer (AFCT) enabled by the presence of the allyl sulfide relieves stress in these methacrylate-based systems while retaining excellent mechanical properties owing to the high glass transition temperature of norbornene-containing resins. Methods An allyl sulfide-containing dinorbornene was stoichiometrically formulated with a ring-containing allyl sulfide-possessing methacrylate. To evaluate the stress relaxation effect as a function of the allyl sulfide concentration, a propyl sulfide-based dinorbornene, not capable of addition-fragmentation, was also formulated with the methacrylate monomer. Shrinkage stress, the glass transition temperature and the elastic modulus were all measured. The composite flexural strength and modulus were also measured. ANOVA (CI 95%) was conducted to determine differences between the means. Results Increasing the allyl sulfide content in the resin dramatically reduces the final stress in the norbornene-methacrylate systems. Both norbornene-methacrylate resins demonstrated almost zero stress (more than 96% stress reduction) compared with the conventional BisGMA/TEGDMA 70/30 wt% control. Mechanical properties of the allyl sulfide-based dental composites were improved to the point of being statistically indistinguishable from the control BisGMA-TEGDMA by changing the molar ratio between the methacrylate and norbornene functionalities. Significance The allyl sulfide-containing norbornene-methacrylate networks possessed super-ambient Tg, and demonstrated significantly lower shrinkage stress when compared with the control (BisGMA/TEGDMA 70 to 30 wt%). Although additional development remains, these low stress materials exhibit excellent mechanical

  10. 78 FR 24761 - National Institute of Dental & Craniofacial Research; Notice of Closed Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-26

    ... HUMAN SERVICES National Institutes of Health National Institute of Dental & Craniofacial Research... personal privacy. Name of Committee: National Institute of Dental and Craniofacial Research Special Emphasis Panel; Design and Development of Novel Dental Composite Restorative Systems Review Panel....

  11. Clinical placement and performance of composite resin restorations.

    PubMed

    Rupp, N W

    1979-05-01

    The most frequent complaints registered against composite restorations are stained margins and a rough surface. The stained margins have many causes such as (1) fracturing or crazing of enamel during preparation of the cavity, (2) using a composite having an excessive curing shrinkage, (3) manipulating too slowly, which permits a loss of plasticity during placement, (4) maintaining inadequate pressure during setting or curing of the composite, and (5) using finishing instruments which cause defects in the margin area of the tooth and/or composite. All of these the operator can control, and if not, the defect will be built into the restoration. The roughness of composites can be reduced by polishing with the finest grit available in disks and by coating with a glaze. Today's composite restorations placed with care will provide long lasting esthetic restorations providing they are not placed in areas subjected to load bearing abrasion. PMID:374440

  12. Fluoride Release and Uptake of Five Dental Restoratives from Mouthwashes and Dentifrices

    PubMed Central

    Rao, B Saketh Rama; Moosani, Gopi Krishna Reddy; Shanmugaraj, Muthu; Kannapan, Balamurugan; Shankar, B. Shiva; Ismail, Prabu Mahin Syed

    2015-01-01

    Background: This study evaluated the fluoride release and uptake of five common dental restoratives mainly glass ionomer formulations, including a conventional glass ionomer, a relatively new caries stabilization glass ionomer and resin-modified glass ionomer (Fuji II, Fuji VII and Fuji II LC); one compomer (F2000); and one fluoride releasing composite resin (tetric ceram). Materials and Methods: A total of 12 cylindrical specimens for each of the five materials were prepared following manufacturer’s instructions for manipulation and immersed independently in 25 ml of artificial saliva and stored as five groups Group I-V. Each group was further divided into three sub Groups A, B, C. The saliva was changed every day in all the specimens. No treatment was carried out for the specimens in subgroup A. The specimens were immersed in 2% sodium fluoride for 1 min before changing saliva in sub group B and the specimens were treated by brushing with a fluoridated dentifrice for 2 min before changing saliva in sub Group C. The fluoride release was evaluated on the 1st, 7th and 28th day using a fluoride ion specific electrode. Results: The results demonstrated that the conventional glass ionomer and the recently introduced caries stabilizing glass ionomer showed similar patterns and quantity of fluoride release, which was significantly higher than the resin-modified glass ionomer, the compomer and the composite resin. The resin-modified glass ionomer showed higher fluoride release than the compomer and the composite resin. All the formulations of glass ionomers showed fluoride uptake from the neutral sodium fluoride and the fluoridated dentifrice, by releasing increased amounts of fluoride after treatment, in comparison with the untreated group. However, the compomer and the composite resin showed no fluoride uptake. Conclusion: The fluoride released by the glass ionomer cements (GICs) was found to be highest during the first 24 h and decreased significantly over the 1st

  13. Novel Dental Composites Reinforced with Zirconia-Silica Ceramic Nanofibers

    PubMed Central

    Guo, Guangqing; Fan, Yuwei; Zhang, Jian-Feng; Hagan, Joseph; Xu, Xiaoming

    2011-01-01

    Objective To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. Methods Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37 °C deionized water for 24 h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey’s Honestly Significant Differences test used for post hoc analysis. Results Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. Significance Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life. PMID:22153326

  14. Priorities for future innovation, research, and advocacy in dental restorative materials.

    PubMed

    Watson, T; Fox, C H; Rekow, E D

    2013-11-01

    Innovations in materials science, both within and outside of dentistry, open opportunities for the development of exciting direct restorative materials. From rich dialog among experts from dental and non-dental academic institutions and industry, as well as those from policy, research funding, and professional organizations, we learned that capitalizing on these opportunities is multifactorial and far from straightforward. Beginning from the point when a restoration is needed, what materials, delivery systems, and skills are needed to best serve the most people throughout the world's widely varied economic and infrastructure systems? New research is a critical element in progress. Effective advocacy can influence funding and drives change in practice and policy. Here we articulate both research and advocacy priorities, with the intention of focusing the energy and expertise of our best scientists on making a difference, bringing new innovations to improve oral health. PMID:24129817

  15. [Atraumatic restorative treatment to control dental caries: history, characteristics, and contributions of the technique].

    PubMed

    Tascón, Jorge

    2005-02-01

    This paper presents relevant scientific information on the history, characteristics, and contributions of atraumatic restorative treatment (ART) for use in preventing and controlling dental caries. Within the area of oral public health, ART has been for years an economical, effective method for preventing and controlling caries in vulnerable populations. Among other things, ART reduces the stress and anxiety in patients that conventional restoration methods produce. This technique promises major benefits for Latin America. However, given its limitations with dental cavities on two or more surfaces, it is recommended that more research on this approach be encouraged, with the aim of improving the technique's effectiveness based on its characteristics, indications, and technical merits. PMID:15826387

  16. An in vitro Evaluation of Microleakage of Posterior Teeth Restored with Amalgam, Composite and Zirconomer – A Stereomicroscopic Study

    PubMed Central

    Punia, Sandhya Kapoor; Bhat, Surekha; Singh, Gautam; Goyal, Pravesh; Oza, Swapnil; Raiyani, Chirag M.

    2015-01-01

    Background Numerous restorative materials are being used in dentistry to achieve adequate strength and restore aesthetics. However, a perfect ideal restorative material has still eluded dentist. Dental amalgam is versatile material with self-sealing property, but is unaesthetic. Other restorative materials like, composites require conservative preparation, but exhibits polymerisation shrinkage resulting in microleakage. To overcome these drawbacks a high strength restorative material reinforced with ceramic and zirconia fillers known as zirconomer has been introduced. The aim of this study was to evaluate the micro-leakage of these three different restorative materials. Materials and Methods Thirty non-carious human permanent first and second molars were utilized in this study. Class I cavities were prepared on the occlusal surface; cavities were then restored with amalgam, composite and zirconomer as per manufacture’s instruction. All samples were stored for 24 hours in distilled water followed by thermocycling. The entire tooth surface was painted with two coats of varnish to within 1mm of the restoration margins. The teeth were immersed in dye. Teeth were sectioned and observed under stereomicroscope. Results In this study the zirconomer exhibited the highest micro leakage as compared to composite and amalgam but composite having higher micro leakage as compared to amalgam and lower micro leakage as compared to zirconomer. Conclusion Even though composite and amalgam are being marketed aggressively and new material like zirconomer are on origin, amalgam still proves to be one of the best materials. PMID:26393208

  17. Reliability and strength of all-ceramic dental restorations fabricated by direct ceramic machining (DCM).

    PubMed

    Filser, F; Kocher, P; Weibel, F; Lüthy, H; Schärer, P; Gauckler, L J

    2001-04-01

    All-ceramic dental bridges for the molar region are not yet available at reasonable costs. The novel direct ceramic machining (DCM) process allows an easy, reliable and rapid fabrication for all-ceramic dental restorations with high mechanical strength and good biocompatibility. In DCM, an enlarged framework is easily milled out of a pre-fabricated porous ceramic blank made of zirconia. After sintering to full density, no further time-consuming hard machining with diamond tools is needed. For individual esthetical requirements, the framework is coated with a veneer porcelain. Compared to the commercially available In-Ceram Alumina and IPS Empress2 restorations, the mechanical strength of zirconia frameworks is twice as high, allowing the restorations to bear the high mastication forces in the molar region. In terms of reliability, zirconia bridges fabricated by the DCM process are also superior to In-Ceram Alumina and IPS Empress2. A clinical study of three-unit dental bridges in the molar region found no problems after the first year of observation. PMID:11697309

  18. Shrinkage of Dental Composite in Simulated Cavity Measured with Digital Image Correlation

    PubMed Central

    Li, Jianying; Thakur, Preetanjali; Fok, Alex S. L.

    2014-01-01

    Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage. Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions. The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the “tooth-restoration” interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material. PMID:25079865

  19. Effect of Source Bandwidth, Focusing and Fluence on the Depth Of Cure in Polymer Dental Composites

    NASA Astrophysics Data System (ADS)

    Pradhan, Ranjit; Melikechi, Noureddine; Eichmiller, Frederick

    2000-03-01

    Photo-curable polymer dental composites are widely used in restorative dental applications. These composites are typically cured using a conventional curing lamp with broad band visible irradiation between 400-500 nm. Argon ion laser-based sources are now available in dentistry for curing applications. This work reports on the dependence of depth of cure on the wavelength bandwidth, the focusing geometry and the irradiation fluence of the curing light source. The depth of cure resulting from a narrow band irradiation source such as the 488 line of the Argon ion laser is observed to be higher than that resulting from broadband irradiation sources such as the curing lamp or the multiline Argon ion laser with lines between 450-500 nm. For the same total irradiation energy deposited into the polymer a focused beam yields higher depth of cure than a non-focused beam.

  20. Practitioner, patient, and caries lesion characteristics associated with type of material used to restore carious teeth: findings from The Dental PBRN

    PubMed Central

    Makhija, Sonia K; Gordan, Valeria V.; Gilbert, Gregg H.; Litaker, Mark S.; Rindal, D. Brad; Pihlstrom, Daniel J.; Qvist, Vibeke

    2011-01-01

    Background The authors conducted a study to identify factors associated with material use by dentists in The Dental Practice-Based Research Network (DPBRN) when placing the first restoration on permanent tooth surfaces. Methods A total of 182 DPBRN practitioner-investigators provided data on 5,599 posterior teeth with caries. Practitioner-investigators completed an enrollment questionnaire that included the dentist’s age, gender, practice workload, practice type, and years since graduation. When a consented patient presented with a previously un-restored carious surface, practitioner-investigators recorded patient and tooth characteristics. Results Amalgam was used more often than direct resin-based composite (RBC) for posterior carious lesions. Practitioner/practice characteristics (years since graduation and type of practice); patient characteristics (gender, race, age, and dental insurance); and lesion characteristics (tooth location and surface, pre-and post-operative depth) were associated with the type of restorative material used. Conclusions There are several practitioner/practice, patient, and lesion characteristics significantly associated with use of amalgam and RBC: region, years since graduation, dental insurance, tooth location and surface, and pre-and post-operative depth. Clinical implications Amalgam remains a material commonly used by United States dentists to restore posterior caries lesions. PMID:21628683

  1. Microleakage of silorane- and methacrylate-based class V composite restorations.

    PubMed

    Krifka, Stephanie; Federlin, Marianne; Hiller, Karl-Anton; Schmalz, Gottfried

    2012-08-01

    The marginal integrity of class V restorations in a silorane- and a group of methacrylate-based composite resins with varying viscosities was tested in the present study. Different adhesives (OptiBond FL, KerrHawe; AdheSE One, Vivadent; or Silorane System Adhesive, 3M ESPE) were applied to 168 standardized class V cavities. The cavities (n = 12) were filled with a wide range of different viscous composite resins: Filtek Silorane, 3M ESPE; els and els flow, Saremco; Tetric EvoCeram and Tetric EvoFlow, Vivadent; Grandio, Voco; and Ultraseal XT Plus, Ultradent. Microleakage of the restoration was assessed by dye penetration (silver staining) on multiple sections with and without thermocycling and mechanical loading (TCML: 5,000 × 5-55°C; 30 s/cycle; 500,000 × 72.5 N, 1.6 Hz). Data were statistically analyzed with the Mann-Whitney U test and the Error Rates Method (ERM). The silorane-based composite resin yielded the lowest dye penetration after TCML. Microleakage of methacrylate-based composite restorations, in general (ERM), was statistically significantly influenced by the adhesive system, Moreover, dye penetration at enamel margins was significantly lower than dye penetration at dentin margins. The chemical basis of composite resins and adjacent tooth substance seems to strongly influence marginal sealing of class V restorations for methacrylate-based materials. Moreover, the steps of dental adhesives used affected marginal integrity. The silorane-based composite resin evaluated in the present study exhibits the best marginal seal. The three-step adhesive yielded better marginal sealing than the one-step adhesive for methacrylate-based class V composite restorations. PMID:21947906

  2. The scalpel finishing technique: a tooth-friendly way to finish dental composites in anterior teeth.

    PubMed

    Kup, Elaine; Tirlet, Gil; Attal, Jean-Pierre

    2015-01-01

    Optimal results can be obtained on direct restorations by the application of layering procedures that combine the accurate morphological insertion of restorative materials with the knowledge of the optical and mechanical properties of both composite resin and natural hard dental tissue. Even if the finishing procedures on restorations, such as margination (the trimming of margins), are minimized by anatomical layering techniques, finishing can still be highly complicated due to a number of pre-finishing sequences using specific instruments proposed in the literature, which include finishing burs and abrasive discs. Finishing procedures performed with a scalpel on polymerized direct composite restorations can improve the quality of the final sculptured surface by developing natural contours and characteristics and by removing the excess restorative material at the tooth-structure margin. Enhanced movement control and fine fingertip perception of the surface texture while moving the scalpel blade allow the operator to detect and cut the excess composite material during the margination procedure and to refine the final anatomy. Avoiding the use of finishing burs during finishing procedures on direct composite restorations may save adjacent enamel surfaces from abrasive damage. The composite surface and margins may also benefit from using the scalpel finishing technique, considering the potential risk of excess removal and surface crazing that the improper use of finishing burs could cause to composite material. The purpose of this article is to propose and describe the scalpel finishing technique step by step, as well as to briefly discuss the advantages of its application within the limits of a clinical case report. PMID:25874271

  3. Immediately restored dental implants for partial-arch applications. A literature update.

    PubMed

    Carrillo García, Celia; Boronat López, Araceli; Peñarrocha Diago, Miguel

    2008-07-01

    This article carries out a literature update on immediately restored dental implants in partially edentulous patients. A search was made in Medline of all articles published between the year 2000 and February 2007, including all articles published in both English and Spanish, in which immediate restoration of implants was made of partially edentulous areas with a minimum of 12 implants and six months follow-up. Certain decisive factors exist for the success of this technique in partially edentulous patients, such as primary stability, a roughened implant surface, and the absence of parafunctional habits in patients acceptable for this type of treatment. Following the analysis of these studies of immediate restoration of teeth in partially edentulous areas, a weighted mean survival of 95.39% was observed. In spite of the high success rate, major controversy still exists on this subject resulting in few studies and short follow-up periods, making the routine use of this technique questionable. PMID:18587310

  4. Physicochemical characterization of three fiber-reinforced epoxide-based composites for dental applications.

    PubMed

    Bonon, Anderson J; Weck, Marcus; Bonfante, Estevam A; Coelho, Paulo G

    2016-12-01

    Fiber-reinforced composite (FRC) biomedical materials are in contact with living tissues arising biocompatibility questions regarding their chemical composition. The hazards of materials such as Bisphenol A (BPA), phthalate and other monomers and composites present in FRC have been rationalized due to its potential toxicity since its detection in food, blood, and saliva. This study characterized the physicochemical properties and degradation profiles of three different epoxide-based materials intended for restorative dental applications. Characterization was accomplished by several methods including FTIR, Raman, Brunauer-Emmett-Teller (BET) Analysis, X-ray fluorescence spectroscopy, and degradation experiments. Physicochemical characterization revealed that although materials presented similar chemical composition, variations between them were more largely accounted by the different phase distribution than chemical composition. PMID:27612785

  5. Morphology, size distribution and elemental composition of several dental debris

    NASA Astrophysics Data System (ADS)

    Abe, Shigeaki; Iwadera, Nobuki; Esaki, Mitsue; Aoyama, Ken-Ichi; Akasaka, Tsukasa; Uo, Motohiro; Morita, Manabu; Yawaka, Yasutaka; Watari, Fumio

    2012-12-01

    We investigated morphologies, size distributions and elemental compositions of dental debris formed by cutting/grinding teeth or dental alloys. The average size of debris formed by cutting/grinding dental alloy was around 100 μm and that of teeth was 20 μm. The debris formed by grinding with diamond or carborundum point had isotropic irregular shape, while the debris formed by cutting with carbide bar had characteristic lathe-cut shape. The elemental analysis indicated that the debris formed by grinding dental alloy with carborundum point consisted of not only the particles of the alloy but also the particles of Si compounds with the size of around 10 μm. The particles of Si compounds would be formed by abrasion of the grinding instrument (carborundum, SiC). Similarly, the debris formed by grinding with diamond point also contained submicro-sized particles consisting of C compounds. The results indicate that the morphology and composition of dental debris are varied depending on the combination between the workpiece and the cutting/grinding materials and that the dental debris consist of both the workpiece and the cutting/grinding materials in some combination. In addition, some of the debris of tooth had the size less than 2 μm, which has a potential to induce inflammation. Though the inflammation can be expected at low level, it is required to investigate the details in future.

  6. Dental implants with the periodontium: a new approach for the restoration of missing teeth.

    PubMed

    Lin, Cheng; Dong, Qing-Shan; Wang, Lei; Zhang, Jun-Rui; Wu, Li-An; Liu, Bao-Lin

    2009-01-01

    Tooth loss is a common occurrence in mankind and damages human health. Osseointegrated dental implants have been successfully used as a popular prosthetic restoration for the missing teeth for many years. However, osseointegration, representing a direct connection between the implant and bone tissue without the periodontium, causes some inevitable problems, such as masticatory force concentration and immobility of the dental implant. Thus, an ideal dental implant should have its own peri-implant periodontium, as do the natural teeth. A number of attempts have been made to reconstruct the periodontium around the implants. Unfortunately, it has been established that a predictable periodontal reconstruction, especially the acellular cementum reconstruction on the surface of the implant, is a very difficult task. In this paper, we propose the hypothesis that the cementum may be a special phenotype of the bone tissue, on the basis of its strong similarity in development, structure, and function. In a certain condition, the bone tissue may change to cementum for special functional needs. In accordance with this hypothesis, we consider a novel approach to reconstruct the peri-implant tissues. Unlike previous studies, this approach imitates the tooth re-plantation process. The key point is to convert the implant-surrounding bone tissues to cementum as a result of adaptive changes to the implant-support demands. This hypothesis, if proven to be valid, will not only represent a breakthrough in cementum research, but also will open a new door to the restoration of missing teeth. PMID:18829177

  7. Optimizing tooth form with direct posterior composite restorations.

    PubMed

    Raghu, Ramya; Srinivasan, Raghu

    2011-10-01

    Advances in material sciences and technology have provided today's clinicians the strategies to transform the mechanistic approach of operative dentistry into a biologic philosophy. In the last three decades, composite resins have gone from being just an esthetically pleasing way of restoring Class III and Class IV cavities to become the universal material for both anterior and posterior situations as they closely mimic the natural esthetics while restoring the form of the human dentition. In order to enhance their success, clinicians have to rethink their protocol instead of applying the same restorative concepts and principles practiced with metallic restorations. Paralleling the evolution of posterior composite resin materials, cavity designs, restorative techniques and armamentarium have also developed rapidly to successfully employ composite resins in Class II situations. Most of the earlier problems with posterior composites such as poor wear resistance, polymerization shrinkage, postoperative sensitivity, predictable bonding to dentin, etc., have been overcome to a major extent. However, the clinically relevant aspect of achieving tight contacts in Class II situations has challenged clinicians the most. This paper reviews the evolution of techniques and recent developments in achieving predictable contacts with posterior composites. A Medline search was performed for articles on "direct posterior composite contacts." The keywords used were "contacts and contours of posterior composites." The reference list of each article was manually checked for additional articles of relevance. PMID:22144797

  8. Voids in Sonic Fill(TM) restorations compared to traditional incrementally-filled composite restorations

    NASA Astrophysics Data System (ADS)

    Abourezq, Ibraheem A.

    SonicFill(TM) is a new composite resin and delivery system designed to provide rapid filling of cavity preparations by decreasing viscosity through application of sonic energy. However, it may produce unwanted air voids in the final restoration due to the short filling time. Air voids compromise long-term performance by providing weak foci, discontinuity at cavosurface margins and at internal cavity walls, and potential crack propagation. This study assessed the locations, sizes, and numbers of voids in SonicFill restorations compared with traditional composite resin restorations in a set of extracted molars with mesio-occlusal-distal (MOD) cavity preparations. Fifty noncarious intact extracted third molars were collected randomly from a large collection of discarded anonymous tooth specimens. Standardized MOD cavity preparations were cut, and teeth were assigned randomly to one of two groups ( n = 25). The first group was restored with SonicFill composite in two steps. The second group was restored with Herculite Ultra(TM) using an multiple increment layering technique (1-2 mm per layer). Cross-sectional images of the filling were taken by digital microscope. A total of 196 voids were found in the 50 specimens: 97 in SonicFill restorations and 99 in conventional restorations. Mean number of voids in SonicFill restorations was 3.88 versus 3.96 for conventional restorations. Mean percentage of void area in SonicFill restorations was 0.588% versus 0.508% for conventional restorations. Unpaired t tests for these differences indicated no statistically significant differences (p =.931 and p =.629, respectively). One-way ANOVA tests for mean void count and mean void area percentage differences by three location zones for conventional and SonicFill restorations also indicated no significant differences among the groups. The bulk-fill SonicFill system does not result in increased or decreased numbers or ii area of voids within Class II MOD restorations compared with a

  9. Rugometric and microtopographic non-invasive inspection in dental-resin composites and zirconia ceramics

    NASA Astrophysics Data System (ADS)

    Fernández-Oliveras, Alicia; Costa, Manuel F. M.; Pecho, Oscar E.; Rubiño, Manuel; Pérez, María. M.

    2013-11-01

    Surface properties are essential for a complete characterization of biomaterials. In restorative dentistry, the study of the surface properties of materials meant to replace dental tissues in an irreversibly diseased tooth is important to avoid harmful changes in future treatments. We have experimentally analyzed the surface characterization parameters of two different types of dental-resin composites and pre-sintered and sintered zirconia ceramics. We studied two shades of both composite types and two sintered zirconia ceramics: colored and uncolored. Moreover, a surface treatment was applied to one specimen of each dental-resin. All the samples were submitted to rugometric and microtopographic non-invasive inspection with the MICROTOP.06.MFC laser microtopographer in order to gather meaningful statistical parameters such as the average roughness (Ra), the root-mean-square deviation (Rq), the skewness (Rsk), and the kurtosis of the surface height distribution (Rku). For a comparison of the different biomaterials, the uncertainties associated to the surface parameters were also determined. With respect to Ra and Rq, significant differences between the composite shades were found. Among the dental resins, the nanocomposite presented the highest values and, for the zirconia ceramics, the pre-sintered sample registered the lowest ones. The composite performance may have been due to cluster-formation variations. Except for the composites with the surface treatment, the sample surfaces had approximately a normal distribution of heights. The surface treatment applied to the composites increased the average roughness and moved the height distribution farther away from the normal distribution. The zirconia-sintering process resulted in higher average roughness without affecting the height distribution.

  10. Adjunctive role of dental restorations in personal identification of burnt victims

    PubMed Central

    Vandrangi, Sameer Kumar; Radhika, MB; Paremala, K; Reshma, V; Sudhakara, M; Hosthor, Sreelatha S

    2016-01-01

    Background: Fire remains one of the major causes of morbidity and mortality throughout the world and identification of a body from the fatal fire remains a daunting task. Several forensic cases involve interpretation of burnt human bodies from airline and automobile accidents, bombings and unlawful cremation. Fire is also involved in homicides, suicides, accidental death, arson and in attempts to destroy forensic evidence in criminal cases. Soft tissue destruction from fire can be so extensive that conventional methods of identification may be impossible. However, teeth survive even high temperatures due to their resistant composition and so, obviously, the restorative material housed in the teeth are even more secure and can yield valuable information in personal identification. Aim: To assess the usefulness of most common restorations in personal identification in burnt cases. Materials and Methods: The study was conducted on 40 extracted teeth which were divided into four groups (Group 1 - Unrestored teeth, Group 2 - Amalgam restored, Group 3 - Glass ionomer restored and Group 4 - Composite resin restored teeth. The effect of incineration at 200°C, 400°C, 600°C, 800°C, 1000°C for 15 min at each target temperature followed by subsequent cooling was studied. Results: Amalgam restoration was resistant and intact even at 1000°C, whereas GIC and composite restoration are identifiable till 600°C, the residual cavity preparation leaves a clue for narrowing down the spectrum of identification. PMID:27194881

  11. New Design for Rapid Prototyping of Digital Master Casts for Multiple Dental Implant Restorations

    PubMed Central

    Romero, Luis; Jiménez, Mariano; Espinosa, María del Mar; Domínguez, Manuel

    2015-01-01

    Aim This study proposes the replacement of all the physical devices used in the manufacturing of conventional prostheses through the use of digital tools, such as 3D scanners, CAD design software, 3D implants files, rapid prototyping machines or reverse engineering software, in order to develop laboratory work models from which to finish coatings for dental prostheses. Different types of dental prosthetic structures are used, which were adjusted by a non-rotatory threaded fixing system. Method From a digital process, the relative positions of dental implants, soft tissue and adjacent teeth of edentulous or partially edentulous patients has been captured, and a maser working model which accurately replicates data relating to the patients oral cavity has been through treatment of three-dimensional digital data. Results Compared with the conventional master cast, the results show a significant cost savings in attachments, as well as an increase in the quality of reproduction and accuracy of the master cast, with the consequent reduction in the number of patient consultation visits. The combination of software and hardware three-dimensional tools allows the optimization of the planning of dental implant-supported rehabilitations protocol, improving the predictability of clinical treatments and the production cost savings of master casts for restorations upon implants. PMID:26696528

  12. Eighteenth and nineteenth century dental restoration, treatment and consequences in a British nobleman.

    PubMed

    Cox, M; Chandler, J; Boyle, A; Kneller, P; Haslam, R

    2000-12-01

    This paper examines unusual eighteenth and nineteenth century dental treatment and its consequences, in a nobleman excavated from beneath St. Nicholas' Church, Sevenoaks, Kent, UK in the early 1990s. This rare archaeological case exhibits erosion of dental enamel on the labial surface of all the anterior dentition. A programme of historical research suggests that this might be attributed to the application of an acid-based dental tincture or the use of an abrasive substance to whiten the teeth. Palliative treatment for the consequence of this application was prescribed by Dr Robert Blake of Dublin. Further, it bears witness to three dental restorations, two of gold and one tin. The two gold (foil) fillings are an occlusal in the upper-right second molar and a cervical on the labial surface of the upper left canine. The tin filling is an occlusal in the upper left second molar. Excavation of the carious tissue appears to have been undertaken using a spoon shaped implement. PMID:11132689

  13. Selective Removal of Dental Composite using a Rapidly Scanned Carbon Dioxide Laser.

    PubMed

    Chan, Kenneth H; Fried, Daniel

    2011-01-01

    Dental restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study a carbon dioxide laser operating at high laser pulse repetition rates integrated with a galvanometer based scanner was used to selectively remove composite from tooth surfaces. A diode array spectrometer was used to measure the plume emission after each laser pulse and determine if the ablated material was tooth mineral or composite. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove the composites rapidly from both surfaces with minimal damage to the underlying sound enamel. PMID:21927546

  14. Selective removal of dental composite using a rapidly scanned carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    Dental restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study a carbon dioxide laser operating at high laser pulse repetition rates integrated with a galvanometer based scanner was used to selectively remove composite from tooth surfaces. A diode array spectrometer was used to measure the plume emission after each laser pulse and determine if the ablated material was tooth mineral or composite. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove the composites rapidly from both surfaces with minimal damage to the underlying sound enamel.

  15. Recommendations for conducting controlled clinical studies of dental restorative materials. Science Committee Project 2/98--FDI World Dental Federation study design (Part I) and criteria for evaluation (Part II) of direct and indirect restorations including onlays and partial crowns.

    PubMed

    Hickel, Reinhard; Roulet, Jean-François; Bayne, Stephen; Heintze, Siegward D; Mjör, Ivar A; Peters, Mathilde; Rousson, Valentin; Randall, Ros; Schmalz, Gottfried; Tyas, Martin; Vanherle, Guido

    2007-01-01

    About 35 years ago, Ryge provided a practical approach to the evaluation of the clinical performance of restorative materials. This systematic approach was soon universally accepted. While that methodology has served us well, a large number of scientific methodologies and more detailed questions have arisen that require more rigor. Current restorative materials have vastly improved clinical performance, and any changes over time are not easily detected by the limited sensitivity of the Ryge criteria in short-term clinical investigations. However, the clinical evaluation of restorations not only involves the restorative material per se but also different operative techniques. For instance, a composite resin may show good longevity data when applied in conventional cavities but not in modified operative approaches. Insensitivity, combined with the continually evolving and nonstandard investigator modifications of the categories, scales, and reporting methods, has created a body of literature that is extremely difficult to interpret meaningfully. In many cases, the insensitivity of the original Ryge methods leads to misinterpretation as good clinical performance. While there are many good features of the original system, it is now time to move on to a more contemporary one. The current review approaches this challenge in two ways: (1) a proposal for a modern clinical testing protocol for controlled clinical trials, and (2) an in-depth discussion of relevant clinical evaluation parameters, providing 84 references that are primarily related to issues or problems for clinical research trials. Together, these two parts offer a standard for the clinical testing of restorative materials/procedures and provide significant guidance for research teams in the design and conduct of contemporary clinical trials. Part 1 of the review considers the recruitment of subjects, restorations per subject, clinical events, validity versus bias, legal and regulatory aspects, rationales for

  16. Wear of dental resin composites: insights into underlying processes and assessment methods--a review.

    PubMed

    Turssi, Cecilia Pedroso; De Moraes Purquerio, Benedito; Serra, Mônica Campos

    2003-05-15

    Given the increased aesthetic demands of patients, along with improvements in the formulation of resin composites, the ability of these materials to bond to tooth structures, and concerns about dental amalgam fillings, the applicability of resin composites in dentistry has become increasingly widespread. As resistance to wear represents an important factor in determining the clinical success of resin composite restoratives, the aim of this article was to define what constitutes wear; the major underlying phenomena involved in this process-adhesion, abrasion, fatigue, and corrosion-being described. Discussions were also focused on factors that contribute both to the magnitude and minimization of resin composite wear. Finally, insights were included on both in vivo and laboratory studies used to determine wear resistance. PMID:12687721

  17. Investigation of thiol-ene and thiol-ene-methacrylate based resins as dental restorative materials

    PubMed Central

    Cramer, Neil B.; Couch, Charles L.; Schreck, Kathleen M.; Carioscia, Jacquelyn A.; Boulden, Jordan E.; Stansbury, Jeffrey W.; Bowman, Christopher N.

    2009-01-01

    Objectives The objective of this work was to evaluate thiol-norbornene and thiol-ene-methacrylate systems as the resin phase of dental restorative materials and demonstrate their superior performance as compared to dimethacrylate materials. Methods Polymerization kinetics and overall functional group conversions were determined by Fourier transform infrared spectroscopy (FTIR). Flexural strength and modulus were determined with a 3-point flexural test. Polymerization-induced shrinkage stress was measured with a tensometer. Results Thiol-ene polymer systems were demonstrated to exhibit advantageous properties for dental restorative materials in regards to rapid curing kinetics, high conversion, and low shrinkage and stress. However, both the thiol-norbornene and thiol-allyl ether systems studied here exhibit significant reductions in flexural strength and modulus relative to BisGMA/TEGDMA. By utilizing the thiol-ene component as the reactive diluent in dimethacrylate systems, high flexural modulus and strength are achieved while dramatically reducing the polymerization shrinkage stress. The methacrylate-thiol-allyl ether and methacrylate-thiol-norbornene systems both exhibited equivalent flexural modulus (2.1 ± 0.1 GPa) and slightly reduced flexural strength (95 ± 1 and 101 ± 3 MPa, respectively) relative to BisGMA/TEGDMA (flexural modulus; 2.2 + 0.1 GPa and flexural strength; 112 ± 3 MPa). Both the methacrylate-thiol-allyl ether and methacrylate-thiol-norbornene systems exhibited dramatic reductions in shrinkage stress (1.1 ± 0.1 and 1.1 ± 0.2 MPa, respectively) relative to BisGMA/TEGDMA (2.6 ± 0.2 MPa). Significance The improved polymerization kinetics and overall functional group conversion, coupled with reductions in shrinkage stress while maintaining equivalent flexural modulus, result in a superior overall dental restorative material as compared to traditional bulk dimethacrylate resins. PMID:19781757

  18. Restorative material and other tooth-specific variables associated with the decision to repair or replace defective restorations: findings from The Dental PBRN

    PubMed Central

    Gordan, Valeria V.; Riley, Joseph L.; Worley, Donald C.; Gilbert, Gregg H.

    2012-01-01

    Objectives Using data from dentists participating in The Dental Practice-Based Research Network (DPBRN), the study had 2 main objectives: (1) to identify and quantify the types of restorative materials in the existing failed restorations; and (2) to identify and quantify the materials used to repair or replace those failed restorations. Methods This cross-sectional study used a consecutive patient/restoration recruitment design. Practitioner-investigators recorded data on consecutive restorations in permanent teeth that needed repair or replacement. Data included the primary reason for repair or replacement, tooth surface(s) involved, restorative materials used, and patient demographics. Results Data for 9,875 restorations were collected from 7,502 patients in 197 practices for which 75% of restorations were replaced and 25% repaired. Most of the restorations that were either repaired or replaced were amalgam (56%) for which most (56%) of the material used was direct tooth-colored. The restorative material was 5 times more likely to be changed when the original restoration was amalgam (OR=5.2, p<.001). The likelihood of changing an amalgam restoration differed as a function of the tooth type (OR=3.0, p<.001), arch (OR=6.6, p<.001); and number of surfaces in the original restoration (OR=12.2, p<.001). Conclusion The probability of changing from amalgam to another restorative material differed with several characteristics of the original restoration. The change was most likely to take place when (1) the treatment was a replacement; (2) the tooth was not a molar; (3) the tooth was in the maxillary arch; and (4) the original restoration involved a single surface. PMID:22342563

  19. The decision to repair or replace a defective restoration is affected by who placed the original restoration: findings from the National Dental PBRN

    PubMed Central

    Gordan, Valeria V; Riley, Joseph; Geraldeli, Saulo; Williams, O. Dale; Spoto, Joseph C; Gilbert, Gregg H

    2014-01-01

    Objectives To evaluate how restoration characteristics are associated with the decision to repair or replace an existing restoration. The following hypotheses were studied: Dentists who placed the original restoration are more likely to repair instead of replace restorations (H1) that are in molar teeth; (H2) that are in the upper arch; (H3) that have amalgam restorative material; (H4) if a fracture is not the primary reason for the defect; and (H5) when the restoration comprises more than one surface. Methods This cross-sectional study used a consecutive patient/restoration recruitment design. 194 dentists members of a dental practice-based research network recorded data on restorations in permanent teeth that needed repair or replacement. Results For 6,623 of the 8,770 defective restorations in 6,643 patients, the treatment was provided by the dentist who had not placed the original restoration (75%). The 2-way interaction revealed that dentists who had placed the original restoration often chose to repair when the defective restoration was in a molar, relative to premolar or anterior teeth (OR = 2.2, p < .001); and chose to replace when the restoration had amalgam (OR = 0.5, p < .001), and when it was a fracture compared to another reason (OR = 0.8, p = 001). Conclusion Most dentists are not conservative when they revisit a restoration that they originally placed regardless of type of failure, number of surfaces or material used. However, dentists who had placed the original restoration were significantly more likely to repair it when the defective restoration was in a molar tooth. PMID:25223822

  20. Multispectral near-infrared imaging of composite restorations in extracted teeth

    NASA Astrophysics Data System (ADS)

    Logan, Cooper M.; Co, Katrina U.; Fried, William A.; Simon, Jacob C.; Staninec, Michal; Fried, Daniel; Darling, Cynthia L.

    2014-02-01

    One major advantage of composite restoration materials is that they can be color matched to the tooth. However, this presents a challenge when composites fail and they need to be replaced. Dentists typically spend more time repairing and replacing composites than placing new restorations. Previous studies have shown that near-infrared imaging can be used to distinguish between sound enamel and decay due to the differences in light scattering. The purpose of this study was to use a similar approach and exploit differences in light scattering to attain high contrast between composite and tooth structure. Extracted human teeth with composites (n=16) were imaged in occlusal transmission mode at wavelengths of 1300-nm, 1460-nm and 1550-nm using an InGaAs image sensor with a tungsten halogen light source with spectral filters. All samples were also imaged in the visible range using a high definition 3D digital microscope. Our results indicate that NIR wavelengths at 1460-nm and 1550-nm, coincident with higher water absorption yield the highest contrast between dental composites and tooth structure.

  1. Multispectral Near-Infrared Imaging of Composite Restorations in Extracted Teeth.

    PubMed

    Logan, Cooper M; Co, Katrina U; Fried, William A; Simon, Jacob C; Staninec, Michal; And, Daniel Fried; Darling, Cynthia L

    2014-02-20

    One major advantage of composite restoration materials is that they can be color matched to the tooth. However, this presents a challenge when composites fail and they need to be replaced. Dentists typically spend more time repairing and replacing composites than placing new restorations. Previous studies have shown that near-infrared imaging can be used to distinguish between sound enamel and decay due to the differences in light scattering. The purpose of this study was to use a similar approach and exploit differences in light scattering to attain high contrast between composite and tooth structure. Extracted human teeth with composites (n=16) were imaged in occlusal transmission mode at wavelengths of 1300-nm, 1460-nm and 1550-nm using an InGaAs image sensor with a tungsten halogen light source with spectral filters. All samples were also imaged in the visible range using a high definition 3D digital microscope. Our results indicate that NIR wavelengths at 1460-nm and 1550-nm, coincident with higher water absorption yield the highest contrast between dental composites and tooth structure. PMID:25309098

  2. A study of dentists’ preferences for the restoration of shortened dental arches with partial dentures

    PubMed Central

    Nassani, Mohammad Zakaria; Ibraheem, Shukran; Al-Hallak, Khaled Rateb; Ali El Khalifa, Mohammed Othman; Baroudi, Kusai

    2015-01-01

    Objective: This study aimed to use a utility method in order to assess dentists’ preferences for the restoration of shortened dental arches (SDAs) with partial dentures. Also, the impact of patient age and length of the SDA on dentists’ preferences for the partial dentures was investigated. Materials and Methods: Totally, 104 subjects holding a basic degree in dentistry and working as staff members in a private dental college in Saudi Arabia were interviewed and presented with 12 scenarios for patients of different ages and mandibular SDAs of varying length. Participants were asked to indicate on a standardized visual analog scale how they would value the health of the patient's mouth if the mandibular SDAs were restored with cobalt-chromium removable partial dentures (RPDs). Results: With a utility value of 0.0 representing the worst possible health state for a mouth and 1.0 representing the best, dentists’ average utility value of the RPD for the SDAs was 0.49 (sd= 0.15). Mean utility scores of the RPDs across the 12 SDA scenarios ranged between 0.35 and 0.61. RPDs that restored the extremely SDAs attracted the highest utility values and dentists’ utility of the RPD significantly increased with the increase in the number of missing posterior teeth. No significant differences in dentists’ mean utility values for the RPD were identified among SDA scenarios for patients of different ages. Conclusion: Restoration of the mandibular SDAs by RPDs is not a highly preferred treatment option among the surveyed group of dentists. Length of the SDA affects dentists’ preferences for the RPD, but patient age does not. PMID:26038647

  3. Impact of Technique-Specific Operative Videos on First-Year Dental Students' Performance of Restorative Procedures.

    PubMed

    Patel, Shalizeh A; Barros, Juliana A; Clark, Christina M; Frey, Gary N; Streckfus, Charles F; Quock, Ryan L

    2015-09-01

    The aim of this study was to examine the impact of psychomotor operative video demonstrations on first-year dental students who are performing specific procedures for the first time in a preclinical setting. The class was randomly divided into two groups, and three restorative procedures were selected. On the date on which each procedure was to be performed in the preclinical laboratory for the first time, one group (experimental, n=50) was shown a technique video for that specific procedure immediately before commencing the exercise; the control cohort (n=50) did not view the video. Technical performance on procedures was evaluated by students and two calibrated and blinded examiners. The students' perceptions of the experience were also collected in a survey. All first-year students participated in the study, for a 100% response rate. A Mann-Whitney U test did not show any group differences in technical performance (mean values on preparation: 77.1 vs. 77.8; amalgam: 82.7 vs. 82.8; composite: 79.7 vs. 78.0). A Spearman rho test revealed a significantly higher correlation in 13 out of 25 evaluation categories between student self-assessment and blinded examiner assessment for the experimental group. A chi-square test of questionnaire responses revealed a positive student perception of administering these videos for the preparation (X(2)=4.8, p<0.03), the amalgam restoration (X(2)=12.4, p<0.001), and the composite restoration (X(2)=11.3, p<0.001). The psychomotor video demonstrations did not immediately improve student performance on preclinical operative procedures, but they were well received by students and augmented self-assessment ability. These findings suggest that videos can be a useful teaching aid in a preclinical environment, especially regarding comprehension of concepts. PMID:26329035

  4. Strengthening composite resin restorations with ceramic whisker reinforcement.

    PubMed

    Xu, H H; Schumacher, G E; Eichmiller, F C; Antonucci, J M

    2000-01-01

    Due to their tendency to fracture, current composite formulations are unsuitable for use in large stress-bearing direct posterior restorations that involve cusps. This study investigated the use of single-crystalline ceramic whiskers for the reinforcement of composite resins. The whisker-reinforced composite materials exhibited physical characteristics (i.e., flexural strength, work-of-fracture, and elastic modulus) that were significantly greater (P < 0.05; Student's t test) than those of traditional composite formulations. The experimental materials also had a surface smoothness that was essentially comparable to hybrid composite control specimens. PMID:11404884

  5. Methicillin-resistant Staphylococcus aureus and infection control for restorative dental treatment in nursing homes.

    PubMed

    Hall, David L

    2003-01-01

    The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in nursing home residents now averages 20-35%. This includes both numerous asymptomatic mostly unidentified carriers, and the occasional patient with an active infection. Among the most common sites for positive MRSA colonization are the nares and mouth (saliva). Ohio State University (OSU) dental students perform routine restorative dental care onsite in local nursing homes using portable equipment including handpieces that can generate aerosols. Using a series of cultured test swabs and plates, this pilot study suggests that protection for both dental health care personnel and patients are provided by the following: 1. universal barrier precautions (for example, gloves, gowns, masks, hats, facial shields, glasses), 2. surface disinfectants, 3. pre-op 0.12% chlorhexidene mouth rinses, 4. high volume evacuation, 5. perioral skin scrubs. Additional infection control methods, techniques and equipment were evaluated and compared including rubber dam isolation, hand excavation and bond technique, high-speed air turbine and electric "high" speed handpiece. There was no indication of a special tendency or heightened ability of MRSA to aerosolize. PMID:14650558

  6. Biomechanical model produced from light-activated dental composite resins: a holographic analysis

    NASA Astrophysics Data System (ADS)

    Pantelić, Dejan; Vasiljević, Darko; Blažić, Larisa; Savić-Šević, Svetlana; Murić, Branka; Nikolić, Marko

    2013-11-01

    Light-activated dental composites, commonly applied in dentistry, can be used as excellent material for producing biomechanical models. They can be cast in almost any shape in an appropriate silicone mold and quickly solidified by irradiation with light in the blue part of the spectrum. In that way, it is possible to obtain any number of nearly identical casts. The models can be used to study the behavior of arbitrary structure under mechanical loads. To test the technique, a simple mechanical model of the tooth with a mesio-occluso-distal cavity was manufactured. Composite resin restoration was placed inside the cavity and light cured. Real-time holographic interferometry was used to analyze the contraction of the composite resin and its effect on the surrounding material. The results obtained in the holographic experiment were in good agreement with those obtained using the finite element method.

  7. A dynamic Monte Carlo model for predicting radiant exposure distribution in dental composites: model development and verifications

    NASA Astrophysics Data System (ADS)

    Chen, Yin-Chu; Ferracane, Jack L.; Prahl, Scott A.

    2005-03-01

    Photo-cured dental composites are widely used in dental practices to restore teeth due to the esthetic appearance of the composites and the ability to cure in situ. However, their complex optical characteristics make it difficult to understand the light transport within the composites and to predict the depth of cure. Our previous work showed that the absorption and scattering coefficients of the composite changed after the composite was cured. The static Monte Carlo simulation showed that the penetration of radiant exposures differed significantly for cured and uncured optical properties. This means that a dynamic model is required for accurate prediction of radiant exposure in the composites. The purpose of this study was to develop and verify a dynamic Monte Carlo (DMC) model simulating light propagation in dental composites that have dynamic optical properties while photons are absorbed. The composite was divided into many small cubes, each of which had its own scattering and absorption coefficients. As light passed through the composite, the light was scattered and absorbed. The amount of light absorbed in each cube was calculated using Beer's Law and was used to determine the next optical properties in that cube. Finally, the predicted total reflectance and transmittance as well as the optical property during curing were verified numerically and experimentally. Our results showed that the model predicted values agreed with the theoretical values within 1% difference. The DMC model results are comparable with experimental results within 5% differences.

  8. Accuracy of intraoral and extraoral digital data acquisition for dental restorations

    PubMed Central

    Rudolph, Heike; Salmen, Harald; Moldan, Matthias; Kuhn, Katharina; Sichwardt, Viktor; Wöstmann, Bernd; Luthardt, Ralph Gunnar

    2016-01-01

    ABSTRACT The computer-aided design (CAD) and computer-aided manufacturing (CAM) process chain for dental restorations starts with taking an impression of the clinical situation. For this purpose, either extraoral digitization of gypsum models or intraoral digitization can be used. Despite the increasing use of dental digitizing systems, there are only few studies on their accuracy. Objective This study compared the accuracy of various intraoral and extraoral digitizing systems for dental CAD/CAM technology. Material and Methods An experimental setup for three-dimensional analysis based on 2 prepared ceramic master dies and their corresponding virtual CAD-models was used to assess the accuracy of 10 extraoral and 4 intraoral optical non-contact dental digitizing systems. Depending on the clinical procedure, 10 optical measurements of either 10 duplicate gypsum dies (extraoral digitizing) or directly of the ceramic master dies (intraoral digitizing) were made and compared with the corresponding CAD-models. Results The digitizing systems showed differences in accuracy. However, all topical systems were well within the benchmark of ±20 µm. These results apply to single tooth measurements. Conclusions Study results are limited, since only single teeth were used for comparison. The different preparations represent various angles and steep and parallel opposing tooth surfaces (incisors). For most digitizing systems, the latter are generally the most difficult to capture. Using CAD/CAM technologies, the preparation angles should not be too steep to reduce digitizing errors. Older systems might be limited to a certain height or taper of the prepared tooth, whereas newer systems (extraoral as well as intraoral digitization) do not have these limitations. PMID:27008261

  9. Accuracy of intraoral and extraoral digital data acquisition for dental restorations.

    PubMed

    Rudolph, Heike; Salmen, Harald; Moldan, Matthias; Kuhn, Katharina; Sichwardt, Viktor; Wöstmann, Bernd; Luthardt, Ralph Gunnar

    2016-02-01

    The computer-aided design (CAD) and computer-aided manufacturing (CAM) process chain for dental restorations starts with taking an impression of the clinical situation. For this purpose, either extraoral digitization of gypsum models or intraoral digitization can be used. Despite the increasing use of dental digitizing systems, there are only few studies on their accuracy. Objective This study compared the accuracy of various intraoral and extraoral digitizing systems for dental CAD/CAM technology. Material and Methods An experimental setup for three-dimensional analysis based on 2 prepared ceramic master dies and their corresponding virtual CAD-models was used to assess the accuracy of 10 extraoral and 4 intraoral optical non-contact dental digitizing systems. Depending on the clinical procedure, 10 optical measurements of either 10 duplicate gypsum dies (extraoral digitizing) or directly of the ceramic master dies (intraoral digitizing) were made and compared with the corresponding CAD-models. Results The digitizing systems showed differences in accuracy. However, all topical systems were well within the benchmark of ±20 µm. These results apply to single tooth measurements. Conclusions Study results are limited, since only single teeth were used for comparison. The different preparations represent various angles and steep and parallel opposing tooth surfaces (incisors). For most digitizing systems, the latter are generally the most difficult to capture. Using CAD/CAM technologies, the preparation angles should not be too steep to reduce digitizing errors. Older systems might be limited to a certain height or taper of the prepared tooth, whereas newer systems (extraoral as well as intraoral digitization) do not have these limitations. PMID:27008261

  10. Influence of Different Drinks on the Colour Stability of Dental Resin Composites

    PubMed Central

    Topcu, Fulya Toksoy; Sahinkesen, Gunes; Yamanel, Kivanc; Erdemir, Ugur; Oktay, Elif Aybala; Ersahan, Seyda

    2009-01-01

    Objectives The objective of this study was to evaluate the discolouration effects of artificial saliva, granule lemon juice, coffee (without sugar), coca cola, sour cherry juice, fresh carrot juice and red wine on resin-based composite materials that are commonly used in restorative dentistry. Methods Colour of four brands of resin composites (Filtek Z 250 (3M Espe), Filtek Supreme (3M Espe), Quadrant (Cavex), Charisma (Heraeus-Kulzer)) of A2 shade was measured after one day of immersion in eight different solutions. Colour measurements were obtained by using a XL-20 Trismus Colourimeter and colour differences (ΔE) were estimated. For statistical evaluation, analysis of variance (ANOVA), Dunnett and Tukey tests were used at a significance level of 0.05. Results For the four restorative materials tested, the lowest ΔE values were observed in the artificial saliva, while ΔE values were the highest in red wine group. When comparing the four different restorative materials, Filtek Supreme exhibited the least colour changes whereas Filtek Z250 was the least colour-stable. Conclusions Dental resin composites and drinking solutions were significant factors that may affect the colour stability. After immersion for one day, all materials showed visible colour changes. The red wine solution exhibited more staining than others in three groups. Filtek Supreme showed significantly the least colour change due to its nano particle sizes. PMID:19262731

  11. Staining of in vivo subsurface degradation in dental composites with silver nitrate

    SciTech Connect

    Mair, L.H. )

    1991-03-01

    A previously reported technique for staining areas of degradation in dental composite restorations was evaluated in 51 removed restorations. The staining reagent was silver nitrate, which penetrated the degraded subsurface as ionic silver and was subsequently developed into colored deposits of metallic silver. Several artefacts were recognized that resulted in an apparent image of subsurface stain. Most importantly, the presence of a layer of adsorbed silver on the edge of the specimen exaggerated the extent of staining. In order for the true depth of stain to be determined, thin sections of the materials should first be examined with a stereomicroscope to distinguish any contribution from adsorbed silver on the specimen edge. With this regimen, no stain was present in 41% of the restorations, and in a further 30%, the depth of stain was less than 50 microns. In two composites, the depth of stain was greater than 900 microns, and in a number of specimens, localized stain was found in association with attrition scars. Energy-dispersive x-ray analysis indicated that the amount of silver present in the degraded layers was very small. Overall, the results indicated that the staining technique is useful in the study of composite degradation.

  12. Investigations on mechanical behaviour of dental composites.

    PubMed

    Ilie, Nicoleta; Hickel, Reinhard

    2009-12-01

    Since a direct comparison of composites efficacy in clinical studies is very difficult, our study aimed to analyse in laboratory tests under standardised and simulated clinical conditions a large variety of commercial composite materials belonging to eight different materials categories. Thus, 72 hybrid, nano-hybrid, micro-filled, packable, ormocer-based and flowable composites, compomers and flowable compomers were compared in terms of their mechanical behaviour. Flexural strength (FS), flexural modulus (FM), diametric tensile (DTS) and compressive strength (CS) were measured after the samples had been stored in water for 24 h at 37 degrees C. Results were statistically analysed using one-way ANOVA with Tukey HSD post hoc test (alpha = 0.05) as well as partial eta2 statistics. Large varieties between the tested materials within the same material category were found. The hybrid, nano-hybrid, packable and ormocer-based composites do not differ significantly among each other as a material type, reaching the highest FS values. Nano-hybrid composites are characterised by a good FS, the best DTS but a low FM. The lowest mechanical properties achieved the micro-filled hybrids. The flowable composites and compomers showed for all properties comparable result. Both flowable material categories do not differ significantly from the micro-filled composites for the most mechanical properties, showing only a higher DTS. The filler volume was shown to have the highest influence on the measured properties, inducing a maximum FS and FM at a level of 60%, whereas such dependence was not measured for DTS or CS. The influence of the type of material on the mechanical properties was significant but very low, showing the strongest influence on the CS. PMID:19242739

  13. A comparative evaluation of microleakage in class v composite restorations.

    PubMed

    Sooraparaju, Sujatha Gopal; Kanumuru, Pavan Kumar; Nujella, Surya Kumari; Konda, Karthik Roy; Reddy, K Bala Kasi; Penigalapati, Sivaram

    2014-01-01

    Aim. To compare and evaluate the microleakage in class V lesions restored with composite resin with and without liner and injectable nanohybrid composite resin. Materials and Methodology. 60 class V cavities were prepared in 30 freshly extracted teeth. After etching and application of bonding agents these cavities were divided into three groups: Group A (n = 20)-restored with composite resin, Group B (n = 20)-flowable composite resin liner + composite resin, and Group C (n = 20)-restored with injectable composite resin. After curing all the specimens were subjected to thermocycling and cyclic loading. Specimens were stained with 0.5% basic fuchsin and evaluated for dye penetration. Results. Results are subjected to Kruskal Wallis and Wilcoxon test. Conclusion. Within the limitations of this study, none of the three materials were free from microleakage. All the three materials showed more microleakage at gingival margins compared to occlusal margins. Among all the groups G-ænial Flo showed the least microleakage at the gingival wall. PMID:25610465

  14. A Comparative Evaluation of Microleakage in Class V Composite Restorations

    PubMed Central

    Sooraparaju, Sujatha Gopal; Kanumuru, Pavan Kumar; Nujella, Surya Kumari; Konda, Karthik Roy; Reddy, K. Bala Kasi; Penigalapati, Sivaram

    2014-01-01

    Aim. To compare and evaluate the microleakage in class V lesions restored with composite resin with and without liner and injectable nanohybrid composite resin. Materials and Methodology. 60 class V cavities were prepared in 30 freshly extracted teeth. After etching and application of bonding agents these cavities were divided into three groups: Group A (n = 20)—restored with composite resin, Group B (n = 20)—flowable composite resin liner + composite resin, and Group C (n = 20)—restored with injectable composite resin. After curing all the specimens were subjected to thermocycling and cyclic loading. Specimens were stained with 0.5% basic fuchsin and evaluated for dye penetration. Results. Results are subjected to Kruskal Wallis and Wilcoxon test. Conclusion. Within the limitations of this study, none of the three materials were free from microleakage. All the three materials showed more microleakage at gingival margins compared to occlusal margins. Among all the groups G-ænial Flo showed the least microleakage at the gingival wall. PMID:25610465

  15. Reasons for Retreatment of Amalgam and Composite Restorations among the Patients Referring to Tabriz Faculty of Dentistry

    PubMed Central

    Kimyai, Soodabeh; Mehdipour, Masomeh; Savadi Oskoee, Siavash; Alizadeh Oskoee, Parnian; Abbaszadeh, Armin

    2007-01-01

    Background and aims Retreatment of existing restorations not only requires a lot of money and time but also there is a danger of weakening tooth structure and irritating the pulp. Since awareness of the reasons for the retreatment of teeth will save the teeth from possible future failure, the aim of this study was to assess the reasons for retreatment of amalgam and composite restorations in patients referring to Tabriz Faculty of Dentistry. Materials and methods In this descriptive study, the subjects had previously received an amalgam or a composite restoration in the Operative Department by dental students and were judged to need retreatment in their second visit. A total of 300 defective teeth were selected by simple random sampling method. The data was collected through examination and questionnaires and analyzed using chi-square test. Results There was a statistically significant association between the type of the restorative material and the reason for retreatment (p=0.001). Conclusion Although the reasons for the retreatment of amalgam and composite restorations were different, recurrent caries was the main reason for the retreatment for both restorative materials. PMID:23277830

  16. Effects of incorporating nanosized calcium phosphate particles on properties of whisker-reinforced dental composites.

    PubMed

    Xu, Hockin H K; Sun, Limin; Weir, Mike D; Takagi, Shozo; Chow, Laurence C; Hockey, Bernard

    2007-04-01

    Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically-strong and caries-inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1-56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean +/- SD; n = 5) decreased from 174 +/- 26 MPa to 138 +/- 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 +/- 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 +/- 0.04 mmol/L to 1.74 +/- 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 +/- 0.21 mmol/L to 9.95 +/- 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction v(MCPM) in the resin: [Ca]= 42.9 v(MCPM) (2.7), and [PO4] = 48.7 v(MCPM) (1.4). In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca- and PO4-releasing composites with mechanical properties matching or exceeding a commercial stress-bearing, nonreleasing composite. This method may be applicable to the use of other Ca-PO4 fillers in developing composites with high stress-bearing and caries-preventing capabilities, a combination not yet available in any dental materials. PMID:16924611

  17. Effects of Incorporating Nanosized Calcium Phosphate Particles on Properties of Whisker-Reinforced Dental Composites

    PubMed Central

    Xu, Hockin H. K.; Sun, Limin; Weir, Mike D.; Takagi, Shozo; Chow, Laurence C.; Hockey, Bernard

    2009-01-01

    Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically-strong and caries-inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1–56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean ± SD; n = 5) decreased from 174 ± 26 MPa to 138 ± 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 ± 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 ± 0.04 mmol/L to 1.74 ± 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 ± 0.21 mmol/L to 9.95 ± 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction vMCPM in the resin: [Ca]= 42.9 vMCPM2.7, and [PO4] = 48.7 vMCPM1.4. In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca- and PO4-releasing composites with mechanical properties matching or exceeding a commercial stress-bearing, nonreleasing composite. This method may be applicable to the use of other Ca–PO4 fillers in developing composites with high stress-bearing and caries-preventing capabilities, a combination not yet available in any dental materials. PMID:16924611

  18. Dental sealants and restorations and urinary bisphenol A concentrations in children in the 2003-2004 National Health and Nutrition Examination Survey

    PubMed Central

    McKinney, Christy; Rue, Tessa; Sathyanarayana, Sheela; Martin, Michael; Seminario, Ana Lucia; DeRouen, Timothy

    2015-01-01

    Background Resin-based dental sealants and composites contain bisphenol A-glycidyl methacrylate, a bisphenol A (BPA) derivative. The authors hypothesized that a greater number of sealants or restorations would be associated with higher urinary BPA concentrations. Methods The authors examined urinary BPA measurements (in nanograms per milliliter) and oral examination data for 1,001 children aged 6 to 19 years from the dataset of the 2003-2004 National Health Examination and Nutrition Survey (NHANES). They categorized children into four groups according to number of occlusal sealants and number of restorations, separately. They estimated associations by using unadjusted and adjusted tobit regression models. Results The lowest quartile of BPA concentrations ranged from 0.3 ng/mL to 1.9 ng/mL, whereas the highest quartile ranged from 7.3 ng/mL to 149 ng/mL. In adjusted analysis, children with seven to 16 sealants had geometric mean BPA concentrations 25 percent higher than those of children with no sealants (95 percent confidence interval [CI], −14 percent to 82 percent; P = .23). In adjusted analyses, children with seven to 42 restorations had geometric mean BPA concentrations 20 percent higher than those of children with no restorations (95 percent CI, −6 percent to 53 percent; P = .13). Neither of these adjusted estimates was statistically significant. Conclusions Though the findings were in the direction hypothesized, the authors did not observe a statistically significant association between a greater number of sealants or restorations and higher urinary BPA concentrations. Additional studies are needed to determine the extent of oral and systemic exposure to BPA from resin-based dental restorative materials over time. Practical Implications Dentists should follow this issue carefully as it develops and as the body of evidence grows. There is insufficient evidence to change practice at this time. PMID:24982281

  19. Dental students' ability to assess their performance in a preclinical restorative course: comparison of students' and faculty members' assessments.

    PubMed

    Tuncer, Duygu; Arhun, Neslihan; Yamanel, Kıvanç; Çelik, Çiğdem; Dayangaç, Berrin

    2015-06-01

    Dental education consists of both theoretical and practical learning for students to develop competence in treating patients clinically. When dental students encounter practical courses in their first year as a new educational experience, they must also learn to evaluate themselves. Self-evaluation is an essential skill to learn for dental professionals to keep increasing their competence over the course of their careers. The aim of this study was to compare the assessment scores of second- and third-year dental students and the faculty in two consecutive preclinical practical exams in restorative dentistry courses in a dental school in Turkey. Faculty- and student-assigned scores were calculated from two consecutive preclinical examinations on tooth restorations performed on both artificial casts and phantom patients. The students were formally instructed on grading procedures for tooth preparations, base and restoration placement, and polishing criteria. After each step, each item was assessed by faculty members, the student, and another student. The results indicated that the initial differences between second-year students' assessments of their own preclinical practical ability and that of the faculty decreased among the third-year students. Self-evaluation scores did not indicate whether the third-year students tended to over- or underestimate the quality of their own work. However, the second-year students not only overestimated themselves but thought they were above average. The results point to the need to develop students' self-insight with more exercises and practical training. PMID:26034030

  20. Yellow Nail Syndrome and Nail Lichen Planus may be Induced by a Common Culprit. Focus on Dental Restorative Substances

    PubMed Central

    Baran, Léon-Robert

    2014-01-01

    Different clinical appearances such as Yellow nail syndrome and Lichen planus or lichenoid reactions can originate from close or identical etiologies. They may result from dental restorative materials or metal allergy. Interestingly, the nail sometimes returns to its normal condition, months after the withdrawal of the offending agents. PMID:25593919

  1. Effect of prosthetic restoration on masticatory function in patients with shortened dental arches: a multicentre study.

    PubMed

    Fueki, K; Igarashi, Y; Maeda, Y; Baba, K; Koyano, K; Sasaki, K; Akagawa, Y; Kuboki, T; Kasugai, S; Garrett, N R

    2016-07-01

    The aim of this multicentre study was to investigate the effect of prosthetic restoration for missing posterior teeth on mastication in patients with shortened dental arches (SDAs). Partially dentate patients who had an intact teeth in anterior region and missed distal molar(s) (2-12 missing occlusal units) classified as Kennedy Class I or Class II were recruited from seven university-based dental hospitals in Japan. Of the 125 subjects who underwent baseline (pre-treatment) and follow-up/post-treatment evaluation, 53 chose no replacement of missing teeth and 72 chose treatment with removable partial dentures (n = 53) or implant-supported fixed partial dentures (n = 19). Objective masticatory performance (MP) was evaluated using a gummy jelly test. Perception of chewing ability (CA) was rated using a food intake questionnaire. In the no-treatment group, mean MP and CA scores at baseline were similar to those at follow-up evaluation (P > 0·05). In the treatment group, mean MP after treatment was significantly greater than the pre-treatment mean MP (P < 0·05). However, the mean perceived CA in the treatment groups was similar at pre- and post-treatment (P > 0·05). In a subgroup analysis of subjects in the treatment group, subjects with lower pre-treatment CA showed a significant CA increase after treatment (P = 0·004), but those with higher pre-treatment CA showed a significant decrease in CA (P = 0·001). These results suggest that prosthetic restoration for SDAs may benefit objective masticatory performance in patients needing replacement of missing posterior teeth, but the benefit in subjective chewing ability seems to be limited in subjects with perceived impairment in chewing ability before treatment. PMID:26854877

  2. Effectiveness of benzocaine in reducing deep cavity restoration and post-extraction stress in dental patients

    PubMed Central

    Al-Samadani, Khalid H.; Gazal, Giath

    2015-01-01

    Objectives: To investigate the effectiveness of topical anesthetic, 20% benzocaine in relieving pain and stress in patients following deep cavity restoration and extraction of teeth under local anesthesia (LA). Methods: A prospective clinical trial was conducted from October 2014 until April 2015 at Taibah University, Al Madinah Al Munawarah, Kingdom of Saudi Arabia. Forty-five patients were included in the 20% benzocaine group, and 46 in the normal saline group. Evaluation of the dental stress was made pre-operatively and immediately post-operative treatment using the visual analogue scale (VAS). Furthermore, discomfort of the injections were recorded by the patients after each treatment on standard 100 mm VAS, tagged at the endpoints with “no pain” (0 mm) and “unbearable pain” (100 mm). Results: There were statistically significant differences between the mean stress scores for patients in the benzocaine and normal saline groups post-operatively (p=0.002). There were significant differences between the mean pain scores for patients in the post buccal injection (p=0.001), post palatal injection (p=0.01), and the post inferior alveolar nerve block groups (p=0.02). Buccal, palatal, and inferior alveolar nerve block injections were more painful for patients in the normal saline group than the benzocaine group. Conclusion: This investigation has demonstrated that post-operative stress associated with deep cavity restoration and dental extractions under LA can be reduced by the application of topical anesthetic (20% benzocaine) at the operative site for intra-oral injections. PMID:26593169

  3. Non-thermal atmospheric plasmas in dental restoration: improved resin adhesive penetration

    PubMed Central

    Zhang, Ying; Yu, Qingsong; Wang, Yong

    2014-01-01

    Objective To investigate the influence of non-thermal plasma treatment on the penetration of a model dental adhesive into the demineralized dentin. Methods Prepared dentin surfaces were conditioned with Scotchbond Universal etchant for 15 s and sectioned equally perpendicular to the etched surfaces. The separated halves were randomly selected for treatment with an argon plasma brush (input current 6 mA, treatment time 30 s) or gentle argon air blowing (treatment time 30 s, as control). The plasma-treated specimens and control specimens were applied with a model adhesive containing 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]-propane (BisGMA) and 2-hydroxyethyl methacrylate (HEMA) (mass ratio of 30/70), gently air-dried for 5 s, and light-cured for 20 s. Cross-sectional specimens were characterized using micro-Raman spectral mapping across the dentin, adhesive/dentin interface, and adhesive layer at 1∼micron spatial resolution. SEM was also employed to examine the adhesive/dentin interfacial morphology. Results The micro-Raman result disclosed that plasma treatment significantly improved the penetration of the adhesive, evidenced by the apparently higher content of the adhesive at the adhesive/dentin interface as compared to the control. Specifically, the improvement of the adhesive penetration using plasma technique was achieved by dramatically enhancing the penetration of hydrophilic monomer (HEMA), while maintaining the penetration of hydrophobic monomer (BisGMA). Morphological observation at the adhesive/dentin interface using SEM also confirmed the improved adhesive penetration. The results further suggested that plasma treatment could benefit polymerization of the adhesive, especially in the interface region. Conclusion The significant role of the non-thermal plasma brush in improving the adhesive penetration into demineralized dentin has been demonstrated. The results obtained may offer a better prospect of using plasma in dental restoration to

  4. Clinical practice guidelines for recall and maintenance of patients with tooth-borne and implant-borne dental restorations.

    PubMed

    Bidra, Avinash S; Daubert, Diane M; Garcia, Lily T; Kosinski, Timothy F; Nenn, Conrad A; Olsen, John A; Platt, Jeffrey A; Wingrove, Susan S; Chandler, Nancy Deal; Curtis, Donald A

    2016-01-01

    The purpose of this article is to provide guidelines for patient recall regimen, professional maintenance regimen, and at-home maintenance regimen for patients with tooth-borne and implant-borne removable and fixed restorations. The American College of Prosthodontists (ACP) convened a scientific panel of experts appointed by the ACP, American Dental Association, Academy of General Dentistry, and American Dental Hygienists Association, who critically evaluated and debated recently published findings from 2 systematic reviews on this topic. The major outcomes and consequences considered during formulation of the clinical practice guidelines (CPGs) were risk for failure of tooth- and implant-borne restorations. The panel conducted a roundtable discussion of the proposed guidelines, which were debated in detail. Feedback was used to supplement and refine the proposed guidelines, and consensus was attained. A set of CPGs was developed for tooth-borne restorations and implant-borne restorations. Each CPG comprised (1) patient recall, (2) professional maintenance, and (3) at-home maintenance. For tooth-borne restorations, the professional maintenance and at-home maintenance CPGs were subdivided for removable and fixed restorations. For implant-borne restorations, the professional maintenance CPGs were subdivided for removable and fixed restorations and further divided into biological maintenance and mechanical maintenance for each type of restoration. The at-home maintenance CPGs were subdivided for removable and fixed restorations. The clinical practice guidelines presented in this document were initially developed using the 2 systematic reviews. Additional guidelines were developed using expert opinion and consensus, which included discussion of the best clinical practices, clinical feasibility, and risk-benefit ratio to the patient. To the authors' knowledge, these are the first CPGs addressing patient recall regimen, professional maintenance regimen, and at

  5. The Use of Micro-CT with Image Segmentation to Quantify Leakage in Dental Restorations

    PubMed Central

    Carrera, Carola A.; Lan, Caixia; Escobar-Sanabria, David; Li, Yuping; Rudney, Joel; Aparicio, Conrado; Fok, Alex

    2015-01-01

    Objective To develop a method for quantifying leakage in composite resin restorations after curing, using non-destructive X-ray micro-computed tomography (micro-CT) and image segmentation. Methods Class-I cavity preparations were made in 20 human third molars, which were divided into 2 groups. Group I was restored with Z100 and Group II with Filtek LS. Micro-CT scans were taken for both groups before and after they were submerged in silver nitrate solution (AgNO3 50%) to reveal any interfacial gap and leakage at the tooth restoration interface. Image segmentation was carried out by first performing image correlation to align the before- and after-treatment images and then by image subtraction to isolate the silver nitrate penetrant for precise volume calculation. Two-tailed Student’s t-test was used to analyze the results, with the level of significance set at p<0.05. Results All samples from Group I showed silver nitrate penetration with a mean volume of 1.3 ± 0.7 mm3. In Group II, only 2 out of the 10 restorations displayed infiltration along the interface, giving a mean volume of 0.3 ± 0.3 mm3. The difference between the two groups was statistically significant (p < 0.05). The infiltration showed non-uniform patterns within the interface. Significance We have developed a method to quantify the volume of leakage using non-destructive micro-CT, silver nitrate infiltration and image segmentation. Our results confirmed that substantial leakage could occur in composite restorations that have imperfections in the adhesive layer or interfacial debonding through polymerization shrinkage. For the restorative systems investigated in this study, this occurred mostly at the interface between the adhesive system and the tooth structure. PMID:25649496

  6. Marginal Integrity of Bulk Versus Incremental Fill Class II Composite Restorations.

    PubMed

    Al-Harbi, F; Kaisarly, D; Bader, D; El Gezawi, M

    2016-01-01

    Bulk-fill composites have been introduced to facilitate the placement of deep direct resin composite restorations. This study aimed at analyzing the cervical marginal integrity of bulk-fill vs incremental and open-sandwich class II resin composite restorations after thermomechanical cycling using replica scanning electron microscopy (SEM) and ranking according to the World Dental Federation (FDI) criteria. Box-only class II cavities were prepared in 91 maxillary premolars with the gingival margin placed 1 mm above and below the cemento-enamel junction. Eighty-four premolars were divided into self-etch and total-etch groups, then subdivided into six restorative subgroups (n=7): 1-Tetric Ceram HB (TC) was used incrementally and in the open-sandwich technique with 2-Tetric EvoFlow (EF) and 3-Smart Dentin Replacement (SD). Bulk-fill restoratives were 4-SonicFill (SF), 5-Tetric N-Ceram Bulk Fill (TN), and 6-Tetric EvoCeram Bulk Fill (TE). In subgroups 1-5, Tetric N-Bond self-etch and Tetric N-Bond total-etch adhesives were used, whereas in subgroup 6, AdheSE self-etch and ExciTE F total etch were used. One more group (n=7) was restored with Filtek P90 Low Shrink Posterior Restorative (P9) only in combination with its self-etch P90 System Adhesive. Materials were manipulated and light cured (20 seconds, 1600 mW/cm(2)), and restorations were artificially aged by thermo-occlusal load cycling. Polyvinyl-siloxane impressions were taken and poured with epoxy resin. Resin replicas were examined by SEM (200×) for marginal sealing, and percentages of perfect margins were analyzed. Moreover, samples were examined using loupes (3.5×) and explorers and categorized according to the FDI criteria. Results were statistically analyzed (SEM by Kruskal-Wallis test and FDI by chi-square test) without significant differences in either the replica SEM groups (p=0.848) or the FDI criteria groups (p>0.05). The best SEM results at the enamel margin were in TC+EF/total-etch and SF

  7. Effect of a glaze/composite sealant on the 3-D surface roughness of esthetic restorative materials.

    PubMed

    Perez, Cesar dos Reis; Hirata, Raphael Júnior; da Silva, Antonio Henrique Monteiro da Fonseca Thomé; Sampaio, Eduardo Martins; de Miranda, Mauro Sayão

    2009-01-01

    The main goal of the current study was to evaluate the surface roughness of tooth-colored restorative materials after different finishing/polishing protocols, including a liquid polisher (BisCover, BISCO, Schaumburg, IL, USA). The restorative materials tested included two nanofilled resin composites (Filtek Supreme, 3M Dental Products, St Paul, MN, USA and Grandio, Voco, Cuxhaven, Germany), one resin-modified glass ionomer cement (Vitremer, 3M Dental Products) and one conventional glass ionomer cement (Meron Molar ART, Voco). The finishing/polishing methods were divided into five groups: G1 (compression with Mylar matrix), G2 (finishing with diamond burs), G3 (Sof-Lex, 3M Dental Products), G4 (BisCover, BISCO, after diamond burs) and G5 (BisCover after Sof-Lex). Five cylindrical specimens of each material were prepared for each group according to the manufacturer's instructions. The finishing/polishing methods were performed by a single operator in one direction to avoid variations at low speed (15,000 RPM). The surface roughness was evaluated using a 3-D scanning instrument with two parameters considered (Ra and Rz). The data was analyzed using one-way ANOVA followed by a multiple comparison Tukey's test. The results showed that BisCover (BISCO) was capable of reducing surface roughness and provided polished surfaces for all materials, enhancing smoothness over already polished surfaces (Sof-Lex, 3M Dental Products) and achieving polishing after finishing with diamond burs. PMID:19953776

  8. Whisker-reinforced dental core buildup composites: effect of filler level on mechanical properties.

    PubMed

    Xu, H H; Smith, D T; Schumacher, G E; Eichmiller, F C

    2000-12-15

    The strength and toughness of dental core buildup composites in large stress-bearing restorations need to be improved to reduce the incidence of fracture due to stresses from chewing and clenching. The aims of the present study were to develop novel core buildup composites reinforced with ceramic whiskers, to examine the effect of filler level, and to investigate the reinforcement mechanisms. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whisker surface for improved retention in the matrix. Filler level was varied from 0 to 70%. Flexural strength, compressive strength, and fracture toughness of the composites were measured. A nano-indentation system was used to measure elastic modulus and hardness. Scanning electron microscopy (SEM) was used to examine the fracture surfaces of specimens. Whisker filler level had significant effects on composite properties. The flexural strength in MPa (mean +/- SD; n = 6) increased from (95+/-15) for the unfilled resin to (193+/- 8) for the composite with 50% filler level, then slightly decreased to (176+/-12) at 70% filler level. The compressive strength increased from (149+/-33) for the unfilled resin to (282+/-48) at 10% filler level, and remained equivalent from 10 to 70% filler level. Both the modulus and hardness increased monotonically with filler level. In conclusion, silica particle-fused ceramic single-crystalline whiskers significantly reinforced dental core buildup composites. The reinforcement mechanisms appeared to be crack deflection and bridging by the whiskers. Whisker filler level had significant effects on the flexural strength, compressive strength, elastic modulus, and hardness of composites. PMID:11033564

  9. Composite restorations: influence of flowable and self-curing resin composite linings on microleakage in vitro.

    PubMed

    Peutzfeldt, Anne; Asmussen, Erik

    2002-01-01

    This in vitro study evaluated the microleakage at enamel (occlusal) and dentin (gingival) margins of MOD resin composite restorations made with different incremental insertion techniques. MOD cavities were prepared on 60 extracted human molars with the proximal margins placed 1 mm below the cemento-enamel junction. All teeth were acid-etched and treated with One-Step adhesive, then restored with a hybrid resin composite (Renew) with and without a flowable composite (AEliteflo) or a self-curing composite (Bisfil 2B) as the first increment in the proximal boxes. The time of placement of the second increment in relation to curing of the first increment was also varied. After polishing, the teeth were soaked in 0.5% basic fuchsin for 24 hours, sectioned and evaluated for dye penetration. None of the restorative techniques prevented microleakage at the enamel and dentin margins. However, microleakage at dentin margins were significantly reduced by the use of a flowable composite as the first increment in the proximal boxes. Time of placement in relation to curing had no influence on microleakage. Microleakage was lower at enamel margins than at dentin margins; however, besides microleakage at the enamel-restoration interface, 37 of the 60 restored teeth (62%) displayed at least one white line in enamel adjacent to the composite restoration. PMID:12413221

  10. Advances in dental materials.

    PubMed

    Vaderhobli, Ram M

    2011-07-01

    The use of materials to rehabilitate tooth structures is constantly changing. Over the past decade, newer material processing techniques and technologies have significantly improved the dependability and predictability of dental material for clinicians. The greatest obstacle, however, is in choosing the right combination for continued success. Finding predictable approaches for successful restorative procedures has been the goal of clinical and material scientists. This article provides a broad perspective on the advances made in various classes of dental restorative materials in terms of their functionality with respect to pit and fissure sealants, glass ionomers, and dental composites. PMID:21726695

  11. Margin designs and fracture resistance of incisal resin composite restorations.

    PubMed

    Tan, D E; Tjan, A H

    1992-02-01

    This study measured the resistance to fracture of Class IV resin composite restorations prepared with either butt joints, bevels, or chamfer margins. Seventy extracted intact, non-carious maxillary central incisors, of approximately the same size, were collected and randomly divided into the following seven groups: 90 degrees butt joint (control)), 1 and 2 mm 45 degrees bevels, 1 and 2 mm 60 degrees bevels, and 1 and 2 mm chamfer margins. The teeth were restored with a hybrid resin composite and tested in an Instron Universal testing machine in a compressive mode at 45 degrees to the long axis. Statistical analysis indicated that there were no significant differences between the control group and any of the 1 mm bevel or chamfer margins and that the 2 mm bevel and chamfer margins yielded the highest fracture resistance. PMID:1524737

  12. Effects of the Nd:YAG laser on amalgam dental restorative material: a preliminary study

    NASA Astrophysics Data System (ADS)

    Cernavin, Igor; Hogan, Sean P.

    1996-09-01

    The Nd:YAG laser has been marketed as an instrument for use on both hard and soft dental tissues. Its potential for use on hard tissues is limited but it may be the instrument of choice for use in certain soft tissue procedures. The aim of this study was to examine the effects of the Nd:YAG laser on amalgam restorations which frequently occur on tooth surfaces adjacent to areas of soft tissue which may be subjected to the laser. The amalgam used was Tytin. The laser firing was controlled by a computer and a constant repetition rate of 40 Hz was used. Energy per pulse was altered as follows, 30 mJ, 40 mJ, 60 mJ, 80 mJ, 120 mJ and 140 mJ. Exposure times of 0.05 sec, 0.125 sec, 0.25 sec, 0.5 sec, 1 sec, 2 sec, 3 sec, 4 sec, and 5 sec were used. The width of defect was measured using a Nikon measurescope with 10x magnification and it was established that the damage threshold lies between 0.125 sec and 0.25 sec for 30 mJ per pulse. The data was analyzed using a one way ANOVA statistical test. There was a significant correlation between the width of the defect and energy per pulse setting as well as exposure time. The findings indicate that amalgam restorations are prone to damage from inadvertent laser exposure and clinicians must take measures to protect such restorations during lasing of soft tissues.

  13. Microleakage in class V gingiva-shaded composite resin restorations

    PubMed Central

    Poggio, Claudio; Chiesa, Marco; Dagna, Alberto; Colombo, Marco; Scribante, Andrea

    2012-01-01

    Summary The purpose of this study was to evaluate the microleakage in Class V cavities restored with a new gingiva-shaded microhybrid composite resin and with a conventional microhybrid composite resin using three different dentin bonding systems (DBS). Class V cavities were prepared in sixty freshly extracted human teeth with the incisal margin in enamel and the apical margin in dentin/cementum. Restored specimens, after thermocycling, were placed in 2% methylene blue solution for 24 hours. Longitudinal sections were obtained and studied with a stereomicroscope for assessment of the microleakage according to degree of dye penetration (scale 0–3). Data were analyzed with Kruskal-Wallis test and with Mann-Whitney U-test. In this study there was no leakage in enamel: all the cavities showed no dye penetration at the incisal margins (located in enamel). None of the DBS used eliminated microleakage in apical margins (located in dentin or cementum): three-step total-etch and single-step self-etch were more effective in reducing microleakage in dentin margins when compared with two-step total-etch. This in vitro study concluded that microleakage in Class V cavities restored with the composite resins tested is similar. PMID:22783451

  14. 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

    2016-05-01

    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. PMID:26374655

  15. Improving flexural strength of dental restorative ceramics using laser interference direct structuring

    SciTech Connect

    Daniel, Claus; Drummond, James; Giordano, Russell A.

    2008-01-01

    Zirconia and alumina ceramics restorative materials were treated with laser interference direct structuring using the third harmonic of a short pulse Nd:YAG and tested in a three-point bending test to measure the flexural strength. The surface was restructured in a periodic line like pattern with controlled surface porosity and a surface composite pattern. The composite consist of two different defect states rather than different phase compositions. The resulting mechanical properties are a function of the number of laser pulses, laser energy, and angle in between the laser beams defining the periodic feature distance. This composite effect is comparable with a laminate showing increasing stiffness with decreasing layer thickness. The material s fracture strength could be controlled through the three mentioned laser parameters and in an initial study significantly improved by up to 50% from initial 422 MPa to 630 MPa for alumina and 833 MPa to 1250 MPa for zirconia.

  16. Microleakage of Four Dental Cements in Metal Ceramic Restorations With Open Margins

    PubMed Central

    Eftekhar Ashtiani, Reza; Farzaneh, Babak; Azarsina, Mohadese; Aghdashi, Farzad; Dehghani, Nima; Afshari, Aisooda; Mahshid, Minu

    2015-01-01

    Background: Fixed prosthodontics is a routine dental treatment and microleakage is a major cause of its failure. Objectives: The aim of this study was to assess the marginal microleakage of four cements in metal ceramic restorations with adapted and open margins. Materials and Methods: Sixty sound human premolars were selected for this experimental study performed in Tehran, Iran and prepared for full-crown restorations. Wax patterns were formed leaving a 300 µm gap on one of the proximal margins. The crowns were cast and the samples were randomly divided into four groups based on the cement used. Copings were cemented using zinc phosphate cement (Fleck), Fuji Plus resin-modified glass ionomer, Panavia F2.0 resin cement, or G-Cem resin cement, according to the manufacturers’ instructions. Samples were immersed in 2% methylene blue solution. After 24 hours, dye penetration was assessed under a stereomicroscope and analyzed using the respective software. Data were analyzed using ANOVA, paired t-tests, and Kruskal-Wallis, Wilcoxon, and Mann-Whitney tests. Results: The least microleakage occurred in the Panavia F2.0 group (closed margin, 0.18 mm; open margin, 0.64 mm) and the maximum was observed in the Fleck group (closed margin, 1.92 mm; open margin, 3.32 mm). The Fleck group displayed significantly more microleakage compared to the Fuji Plus and Panavia F2.0 groups (P < 0.001) in both closed and open margins. In open margins, differences in microleakage between the Fuji Plus and G-Cem as well as between the G-Cem and Panavia F2.0 groups were significant (P < 0.001). In closed margins, only the G-Cem group displayed significantly more microleakage as compared to the Panavia F2.0 group (P < 0.05). Paired t-test results showed significantly more microleakage in open margins compared to closed margins, except in the Fuji Plus group (P = 0.539). Conclusions: Fuji Plus cement exhibited better sealing ability in closed and open margins compared to G-Cem and Fleck

  17. Modeling of viscoelastic behavior of dental chemically activated resin composites during curing.

    PubMed

    Dauvillier, B S; Hübsch, P F; Aarnts, M P; Feilzer, A J

    2001-01-01

    Shrinkage stresses generated in dental resin composites during curing are among the major problems in adhesive dentistry, because they interfere with the integrity of the restored tooth. The aim of this study was to find a mechanical model to describe the viscoelastic behavior of a two-paste resin composite during curing, to aid our understanding of the process of shrinkage stress development. In this study, stress-strain data on Clearfil F2 during curing were obtained by a dynamic test method and analyzed using three mechanical models (Maxwell, Kelvin, and the Standard Linear Solid model). With a modeling procedure, the model's stress response was compared with the experimental stress data, and the material parameters were calculated. On the basis of the modeling and evaluation results, a model for describing the viscoelastic behavior of the shrinking resin composite was selected. The validation results showed that the modeling procedure is free of error, and that it was capable of finding material parameters associated with a two-parametric model with a high degree of accuracy. The viscoelastic behavior of the shrinking resin composite, as excited by the conditions of the test method, cannot be described by a single mechanical model. In the early stage of curing, the most accurate prediction was achieved by the Maxwell model, while during the remainder of the curing process the Kelvin model can be used to describe the viscoelastic behavior of the two-paste resin composite. PMID:11152993

  18. Wear of nanofilled dental composites at varying filler concentrations.

    PubMed

    Lawson, Nathaniel C; Burgess, John O

    2015-02-01

    The aim of this study is to examine the effects of nanofiller concentration on the mechanisms of wear of a dental composite. Nanofilled composites were fabricated with a bisphenol A glycidyl methacrylate polymer and 40 nm SiO2 filler particles at three filler loads (25, 50, and 65 wt %). The elastic modulus, flexural strength, and hardness of the composites and the unfilled resin were measured. The materials (n = 8) were tested in the modified wear testing device at 50,000, 100,000, and 200,000 cycles with 20N force at 1 Hz. A 33% glycerine lubricant and stainless steel antagonist were used. The worn composite and antagonist surfaces were analyzed with noncontact profilometry and SEM. The volumetric wear data indicated that there are significant differences between filler concentrations and cycles (p < 0.05). A trend was noted that increasing filler content beyond 25% decreased the wear resistance of the composites. Increasing filler content increased hardness and modulus and increased flexural strength up to 50% fill. SEM evaluation of the worn specimens indicated that the resin and 25% filled materials exhibited cracking and failed by fatigue and the 50 and 65% filled materials exhibited microcutting and failed by abrasive wear. Based on the results of this study, composite manufacturers are recommended to use a filler concentration between 25 and 50% when using nanosized filler particles. PMID:24909664

  19. Electrospun nanofiber reinforcement of dental composites with electromagnetic alignment approach.

    PubMed

    Uyar, Tansel; Çökeliler, Dilek; Doğan, Mustafa; Koçum, Ismail Cengiz; Karatay, Okan; Denkbaş, Emir Baki

    2016-05-01

    Polymethylmethacrylate (PMMA) is commonly used as a base acrylic denture material with benefits of rapid and easy handling, however, when it is used in prosthetic dentistry, fracturing or cracking problems can be seen due to the relatively low strength issues. Besides, acrylic resin is the still prominent material for denture fabrication due to its handy and low cost features. Numerous proposed fillers that are used to produce PMMA composites, however electrospun polyvinylalcohol (PVA) nanofiber fillers for production of PMMA composite resins are not studied as much as the others. The other focus of the practice is to compare both mechanical properties and efficiency of aligned fibers versus non-aligned PVA nanofibers in PMMA based dental composites. Field-controlled electrospinning system is manufactured and provided good alignment in lab scale as one of contributions. Some novel auxiliary electrodes in controlled structure are augmented to obtain different patterns of alignment with a certain range of fiber diameters. Scanning electron microscopy is used for physical characterization to determine the range of fiber diameters. Non-woven fiber has no unique pattern due to chaotic nature of electrospinning process, but aligned fibers have round pattern or crossed lines. These produced fibers are structured as layer-by-layer form with different features, and these features are used in producing PMMA dental composites with different volume ratios. The maximum flexural strength figure shows that fiber load by weight of 0.25% w/w and above improves in the maximum level. As a result, mechanical properties of PMMA dental composites are improved by using PVA nanofibers as a filler, however the improvement was higher when aligned PVA nanofibers are used. The maximum values were 5.1 MPa (flexural strength), 0.8 GPa (elastic modulus), and 170 kJ/m(3) (toughness) in three-point bending test. In addition to the positive results of aligned and non-aligned nanofibers it was found

  20. Measurement for natural dental neck data of normal adults and its clinical significance on guiding implant restoration

    PubMed Central

    Sun, Mingxu; Gu, Fang; Wang, Junjun; Zhou, Chengyuan; Xia, Junnan; Qin, Hongwei; Yang, Jianjun

    2015-01-01

    Objective: Provide reference basis for the clinical implant restoration to select implant diameter through measuring each data of 7 teeth in the dental neck of bilateral upper and lower jaws of the young volunteers with normal dentition. Methods: Select 30 healthy young volunteers with complete dentition but no malocclusion, take cone beam CT (CBCT), measure the mesiodistal and buccolingual distance of the tooth root at 1.5 mm from 14 teeth (bilateral upper and lower jaws) to alveolar crest, trace out the outline of each tooth neck in this layer, calculate the cross sectional area and roundness of each tooth neck according to pixel value calibration, and then carry out statistical processing. Results: Complete the data collection and processing of mesiodistal length, buccolingual width, cross sectional area, and cross sectional roundness of the dental neck at 1.5 mm from these seven teeth of the bilateral upper and lower jaws to the alveolar crest of 30 volunteers, and calculate the mean value, variance, and reference value range of medical science of each index. Conclusion: CBCT can effectively obtain the image information of the dental neck. Through mimics 10.0 and Photoshop CS3, it is possible to accurately calculate the dental neck length and width, and cross sectional area of each tooth according to CBCT image information. This result can provide reference basis for the implant restoration of the clinical teeth. PMID:26628955

  1. Tooth Retrospective Dosimetry Using Electron Paramagnetic Resonance: Influence of Irradiated Dental Composites

    PubMed Central

    Desmet, Céline M.; Djurkin, Andrej; Dos Santos-Goncalvez, Ana Maria; Dong, Ruhong; Kmiec, Maciej M.; Kobayashi, Kyo; Rychert, Kevin; Beun, Sébastien; Leprince, Julian G.; Leloup, Gaëtane; Levêque, Philippe; Gallez, Bernard

    2015-01-01

    In the aftermath of a major radiological accident, the medical management of overexposed individuals will rely on the determination of the dose of ionizing radiations absorbed by the victims. Because people in the general population do not possess conventional dosimeters, after the fact dose reconstruction methods are needed. Free radicals are induced by radiations in the tooth enamel of victims, in direct proportion to dose, and can be quantified using Electron Paramagnetic Resonance (EPR) spectrometry, a technique that was demonstrated to be very appropriate for mass triage. The presence of dimethacrylate based restorations on teeth can interfere with the dosimetric signal from the enamel, as free radicals could also be induced in the various composites used. The aim of the present study was to screen irradiated composites for a possible radiation-induced EPR signal, to characterize it, and evaluate a possible interference with the dosimetric signal of the enamel. We investigated the most common commercial composites, and experimental compositions, for a possible class effect. The effect of the dose was studied between 10 Gy and 100 Gy using high sensitivity X-band spectrometer. The influence of this radiation-induced signal from the composite on the dosimetric signal of the enamel was also investigated using a clinical L-Band EPR spectrometer, specifically developed in the EPR center at Dartmouth College. In X-band, a radiation-induced signal was observed for high doses (25-100 Gy); it was rapidly decaying, and not detected after only 24h post irradiation. At 10 Gy, the signal was in most cases not measurable in the commercial composites tested, with the exception of 3 composites showing a significant intensity. In L-band study, only one irradiated commercial composite influenced significantly the dosimetric signal of the tooth, with an overestimation about 30%. In conclusion, the presence of the radiation-induced signal from dental composites should not

  2. Effects of mercury release from amalgam dental restorations during cremation on soil mercury levels of three New Zealand crematoria

    SciTech Connect

    Nieschmidt, A.K.; Kim, N.D.

    1997-05-01

    A vast amount of research has been undertaken in the last 15-20 years on the corrosion reactions occurring in dental amalgam, release of mercury from amalgam restorations, and the toxic effects of this released mercury on the human body. However, one environmental aspect of amalgam dental restorations that has not received a great deal of attention is the release of mercury during cremation. Mercury is liberated during cremation both because dental amalgams are unstable at cremation temperatures (650-700{degrees}C) and because the free mercury metal is highly volatile. In New Zealand, 58% of deaths are followed by cremation and this figure is likely to rise in the future. This increasing use of cremation as the method of corpse disposal, coupled with the fact that each amalgam restoration is approximately 50% mercury, implies that a significant amount of mercury may be emitted into the environment every year. This study examines mercury released from crematoria in New Zealand. 20 refs., 2 figs., 5 tabs.

  3. Clinical Evaluation of Reasons for Replacement of Amalgam Restorations in Patients Referring to a Dental School in Iran

    PubMed Central

    Pouralibaba, Firoz; Joulaei, Mohammad; Kashefimehr, Atabak; Pakdel, Farzaneh; Jamali, Zahra; Esmaeili, Ali

    2010-01-01

    Background and aims The present study evaluated the most common reasons for replacing amalgam restorations in a university clinic. Materials and methods A total of 217 restorations which needed to be replaced were clinically and radiographically evaluated in a period of 4 months. The frequencies of reasons for replacing amalgam restorations were calculated: The assessed items included recurrent caries, tooth structure fracture (functional or non-functional cusps), amalgam bulk fracture, amalgam marginal fracture, proximal overhangs, and esthetics. Data were analyzed using Fischer’s exact test. Results Both in vital teeth and teeth which had undergone root canal therapy, the most common reason for amalgam replacement was cusp fracture, with the fracture of non-functional cusps being statistically significant. Recurrent caries was the second most common reason for amalgam replacement. In Class I restorations, the most common reasons were recurrent caries and esthetics, with no statistical significance. The most frequent problem in Class II restorations was fracture of non-functional cusps, with a statistical significance in three-surface restorations. Conclusion According to the results, failing to reduce undermined cusps and neglectful caries removal are the reasons for majority of amalgam restoration replacements. These issues should be emphasized in the curriculum for dental students and continuing education courses. PMID:22991598

  4. Modeling the Residual Stresses in Reactive Resins-Based Materials: a Case Study of Photo-Sensitive Composites for Dental Applications

    NASA Astrophysics Data System (ADS)

    Grassia, Luigi; D'Amore, Alberto

    2010-06-01

    Residual stresses in reactive resins-based composites are associated to the net volumetric contraction (shrinkage) arising during the cross-linking reactions. Depending on the restoration geometry (the ratio of the free surface area to the volume of the cavity) the frozen-in stresses can be as high as the strength of the dental composites. This is the main reason why the effectiveness and then the durability of restorations with composites remains quite lower than those realized with metal alloys based materials. In this paper we first explore the possibility to circumvent the mathematical complexity arising from the determination of residual stresses in reactive systems three-dimensionally constrained. Then, the results of our modeling approach are applied to a series of commercially available composites showing that almost all samples develop residual stresses such that the restoration undergoes failure as soon as it is realized.

  5. Modeling the Residual Stresses in Reactive Resins-Based Materials: a Case Study of Photo-Sensitive Composites for Dental Applications

    SciTech Connect

    Grassia, Luigi; D'Amore, Alberto

    2010-06-02

    Residual stresses in reactive resins-based composites are associated to the net volumetric contraction (shrinkage) arising during the cross-linking reactions. Depending on the restoration geometry (the ratio of the free surface area to the volume of the cavity) the frozen-in stresses can be as high as the strength of the dental composites. This is the main reason why the effectiveness and then the durability of restorations with composites remains quite lower than those realized with metal alloys based materials. In this paper we first explore the possibility to circumvent the mathematical complexity arising from the determination of residual stresses in reactive systems three-dimensionally constrained. Then, the results of our modeling approach are applied to a series of commercially available composites showing that almost all samples develop residual stresses such that the restoration undergoes failure as soon as it is realized.

  6. Mathematical modeling of cross-linking monomer elution from resin-based dental composites.

    PubMed

    Manojlovic, Dragica; Radisic, Marina; Lausevic, Mila; Zivkovic, Slavoljub; Miletic, Vesna

    2013-01-01

    Elution of potentially toxic substances, including monomers, from resin-based dental composites may affect the biocompatibility of these materials in clinical conditions. In addition to the amounts of eluted monomers, mathematical modeling of elution kinetics reveals composite restorations as potential chronic sources of leachable monomers. The aim of this work was to experimentally quantify elution of main cross-linking monomers from four commercial composites and offer a mathematical model of elution kinetics. Composite samples (n = 7 per group) of Filtek Supreme XT (3M ESPE), Tetric EvoCeram (Ivoclar Vivadent), Admira (Voco), and Filtek Z250 (3M ESPE) were prepared in 2-mm thick Teflon moulds and cured with halogen or light-emitting diode light. Monomer elution in ethanol and water was analyzed using high-performance liquid chromatography up to 28 days postimmersion. The mathematical model was expressed as a sum of two exponential regression functions representing the first-order kinetics law. Elution kinetics in all cases followed the same mathematical model though differences in rate constants as well as the extent of monomer elution were material-, LCU-, medium-dependent. The proposed mechanisms of elution indicate fast elution from surface and subsurface layers and up to 100 times slower monomer extraction from the bulk polymer. PMID:22997145

  7. Teaching atraumatic restorative treatment in U.S. dental schools: a survey of predoctoral pediatric dentistry program directors.

    PubMed

    Kateeb, Elham T; Warren, John J; Damiano, Peter; Momany, Elizabeth; Kanellis, Michael; Weber-Gasparoni, Karin; Ansley, Tim

    2013-10-01

    The International Dental Federation and World Health Organization have promoted the use of Atraumatic Restorative Treatment (ART) in modern clinical settings worldwide. In the United States, the practice of ART is not believed to be widely used, which may be a result of little attention given to ART training in predoctoral pediatric dentistry curricula in U.S. dental schools. This study investigated the extent of clinical and didactic instruction on ART provided in U.S. dental schools by surveying the predoctoral pediatric dentistry programs in 2010. Of the fifty-seven directors asked to complete the survey, forty-four responded for a response rate of 77 percent. Of these forty-four programs, 66 percent reported providing clinical training on ART, though only 14 percent provide this training often or very often. The types of ART training provided often or very often included interim treatment (18 percent) and single-surface cavities (14 percent) in primary teeth. However, ART was said to be rarely taught as a definitive treatment in permanent teeth (2 percent). Attitude was a major predictor, for clinical training provided and using professional guidelines in treatment decisions were associated with a positive attitude towards ART. These predoctoral pediatric dentistry programs used ART mainly in primary, anterior, and single-surface cavities and as interim treatment. As ART increases access of children to dental care, the incorporation of the ART approach into the curricula of U.S. dental schools should be facilitated by professional organizations. PMID:24098034

  8. Wear of nanofilled dental composites in a newly-developed in vitro testing device

    NASA Astrophysics Data System (ADS)

    Lawson, Nathaniel C.

    Purpose. In vivo wear of dental composites can lead to loss of individual tooth function and the need to replace a composite restoration. To evaluate the wear performance of new and existing dental composites, we developed a novel system for measuring in vitro wear and we used this system to analyze the mechanisms of wear of nanofilled composite materials. Methods. A modified wear testing device was designed based on the Alabama wear testing machine. The new device consists of: (1) an antagonist which is lowered to and raised from the composite specimen by weight loading, (2) a motorized stage to cause the antagonist to slide 2mm on the composite surface, and (3) pumps for applying lubricant to the specimens. Various testing parameters of the device were examined before testing, including the impulse force, the third-body medium, the lubricant and antagonist. The parameters chosen for this study were 20N at 1Hz with a 33% glycerine lubricant and stainless steel antagonist. Three nano-composites were fabricated with a BisGMA polymer matrix and 40nm SiO2 filler particles at three filler loads (25%, 50% and 65%). The mechanical properties of the composites were measured. The materials were then tested in the modified wear testing device under impact wear, sliding wear and a combination of impact and sliding wear. The worn surfaces were then analyzed with a non-contact profilometer and SEM. Results. The volumetric wear data indicated that increasing filler content beyond 25% decreased the wear resistance of the composites. Increasing filler content increased hardness and decreased toughness. SEM evaluation of the worn specimens indicated that the 25% filled materials failed by fatigue and the 50% and 65% filled materials failed by abrasive wear. Impact wear produced fretting in this device and sliding wear is more aggressive than impact wear. Conclusion. Based on the results of this study and previous studies on this topic, manufacturers are recommended to use a filler

  9. Finite element modeling of dental restoration through multi-material laser densification

    NASA Astrophysics Data System (ADS)

    Dai, Kun

    To provide guidance for intelligent selection of various parameters in the Multi-Material Laser Densification (MMLD) process for dental restorations, finite element modeling (FEM) has been carried out to investigate the MMLD process. These modeling investigations include the thermal analysis of the nominal surface temperature that should be adopted during experiments in order to achieve the desired microstructure; the effects of the volume shrinkage due to transformation from a powder compact to dense liquid on the temperature distribution and the size of the transformation zone; the evolution of transient temperature, transient stresses, residual stresses and distortions; and the effects of laser processing conditions, such as fabrication sequences, laser scanning patterns, component sizes, preheating temperatures, laser scanning rates, initial porosities, and thicknesses of each powder layer, on the final quality of the component fabricated via the MMLD process. The simulation results are compared with the experiments. It is found that the predicted temperature distribution matches the experiments very well. The nominal surface temperature applied on the dental porcelain body should be below 1273 K to prevent the forming of the un-desired microstructure (i.e., a leucite-free glassy phase). The simplified models that do not include the volume shrinkage effect provide good estimations of the temperature field and the size of the laser-densified body, although the shape of the laser-densified body predicted is different from that obtained in the experiment. It is also fount that warping and residual thermal stresses of the laser-densified component are more sensitive to the chamber preheating temperature and the thickness of each powder layer than to the laser scanning rate and the initial porosity of the powder layer. The major mechanism responsible for these phenomena is identified to be related to the change of the temperature gradient induced by these laser

  10. Probing the origins and control of shrinkage stress in dental resin-composites: I. Shrinkage stress characterization technique.

    PubMed

    Lu, H; Stansbury, J W; Dickens, S H; Eichmiller, F C; Bowman, C N

    2004-10-01

    The accurate and reliable characterization of the polymerization shrinkage stress is becoming increasingly important, as the shrinkage stress still is a major drawback of current dimethacrylate-based dental materials and restricts its range of applications. The purpose of this research is to develop a novel shrinkage stress measurement device to elucidate the shrinkage stress evolution of dental restorative composites while allowing for controlled sample deformation during the polymerization. Furthermore, the device is designed to mimic the clinically relevant cusp-to-cusp displacement by systematically adjusting the instrument compliance, the bonded surface area/unbonded area by sample geometry, and the total bonded area by sample diameter. The stress measurement device based on the cantilever beam deflection theory has been successfully developed and characterized using a commercial dental composite. It was shown that this device is a highly effective, practical and reliable shrinkage stress measurement tool, which enables its facile applications to the investigation of shrinkage stress kinetics of both commercial and experimental composites, as well as for probing various aspects that dictate shrinkage stress development. PMID:15516870

  11. Optical coherence tomography based imaging of dental demineralisation and cavity restoration in 840 nm and 1310 nm wavelength regions

    NASA Astrophysics Data System (ADS)

    Damodaran, Vani; Rao, Suresh Ranga; Vasa, Nilesh J.

    2016-08-01

    In this paper, a study of in-house built optical coherence tomography (OCT) system with a wavelength of 840 nm for imaging of dental caries, progress in demineralisation and cavity restoration is presented. The caries when imaged with the 840 nm OCT system showed minute demineralisation in the order of 5 μm. The OCT system was also proposed to study the growth of lesion and this was demonstrated by artificially inducing caries with a demineralisation solution of pH 4.8. The progress of carious lesion to a depth of about 50-60 μm after 60 hours of demineralisation was clearly observed with the 840 nm OCT system. The tooth samples were subjected to accelerated demineralisation condition at pH of approximately 2.3 to study the adverse effects and the onset of cavity formation was clearly observed. The restoration of cavity was also studied by employing different restorative materials (filled and unfilled). In the case of restoration without filler material (unfilled), the restoration boundaries were clearly observed. Overall, results were comparable with that of the widely used 1310 nm OCT system. In the case of restoration with filler material, the 1310 nm OCT imaging displayed better imaging capacity due to lower scattering than 840 nm imaging.

  12. BisGMA/TEGDMA dental composite containing high aspect-ratio hydroxyapatite nanofibers

    PubMed Central

    Chen, Liang; Yu, Qingsong; Wang, Yong; Li, Hao

    2011-01-01

    Objectives The objectives of this study are to investigate the properties of high aspect-ratio hydroxyapatite (HAP) nanofibers and the reinforcing effect of such fibers on bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental resins (without silica microparticle filler) and dental composites (with silica microparticle filler) with various mass fractions (loading rates). Methods HAP nanofibers were synthesized using a wet-chemical method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal gravimetric analysis (TGA). Biaxial flexural strength (BFS) of the HAP nanofibers reinforced dental resins without any microsized filler and dental composites with silica microparticle filler was tested and analysis of variance (ANOVA) was used for the statistically analysis of acquired data. The morphology of fracture surface of tested dental composite samples was examined by SEM. Results The HAP nanofibers with aspect-ratios of 600 to 800 can be successfully fabricated with a simple wet-chemical method in aqueous solution. Impregnation of small mass fractions of the HAP nanofibers (5 wt% or 10 wt%) into the BisGMA/TEGDMA dental resins or impregnation of small mass fractions of the HAP nanofibers (2 wt% or 3 wt%) into the dental composites can substantially improve the biaxial flexural strength of the resulting dental resins and composites. A percolation threshold of HAP nanofibers, beyond which more nanofibers will no longer further increase the mechanical properties of dental composites containing HAP nanofibers, was observed for the dental composites with or without silica microparticle filler. Our mechanical testing and fractographic analysis indicated that the relatively good dispersion of HAP nanofibers at low mass fraction is the key reason for the significantly improved biaxial flexural strength, while higher mass fraction of HAP nanofibers tends to lead to bundles that cannot effectively

  13. Biomechanical Stress Analysis of Mandibular First Permanent Molar; Restored with Amalgam and Composite Resin: A Computerized Finite Element Study

    PubMed Central

    Prabhakar, AR

    2010-01-01

    Normal mastication with its varying magnitude and direction generates considerable reactionary stresses in teeth and their supporting tissues. The structure of the human tooth and its supporting tissues is a complex assemblage of materials of varied mechanical properties. The finite element method (FEM), a modern technique of numerical stress analysis, has the great advantage of being applicable to solids of irregular geometry and heterogeneous material properties and therefore ideally suited to the examination of structural behavior of teeth. The mandibular first permanent molar is one of the earliest permanent teeth to erupt in the oral cavity and hence most prone to caries. The purpose of the present study was to construct a two-dimensional FE model of the mandibular first permanent molar and its supporting structures, using a FE software called NISA II-Display III, EMRC, USA to study the following: • To compare stress distributions patterns when a modeled Class I Cavity was restored with dental amalgam and composite resin. • To compare the stress distributions pattern when the load was applied to different to locations, i.e.: At the mesial cusp tip, and at the center of the occlusal surface. Both amalgam and composite resin showed similar stress distribution pattern, however, the magnitudes of stresses generated in the tooth restored with composite resin were higher. Thus, amalgam is a better restorative material in distributing stresses.

  14. Selected mechanical and physical properties and clinical application of a new low-shrinkage composite restoration.

    PubMed

    Duarte, Sillas; Botta, Ana Carolina; Phark, Jin-Ho; Sadan, Avishai

    2009-09-01

    Polymerization shrinkage is a major concern for bonded direct posterior restorations. Recently, a new low-shrinkage composite resin restorative material was developed. However, few data are available regarding clinical manipulation of this composite. Silorane-based composites represent an alternative to conventional methacrylate-based composites for direct posterior restorations. This article critically discusses the latest peer-reviewed reports related to polymerization, bonding, polishing, and color stability of silorane composite, focusing on its clinical application. Initial evaluation of this new category of composite material shows acceptable mechanical and physical properties. PMID:19639087

  15. Effect of a CO2 Laser on the Inhibition of Root Surface Caries Adjacent to Restorations of Glass Ionomer Cement or Composite Resin: An In Vitro Study

    PubMed Central

    Daniel, L. C.; Araújo, F. C.; Zancopé, B. R.; Hanashiro, F. S.; Nobre-dos-Santos, M.; Youssef, M. N.; Souza-Zaroni, W. C.

    2015-01-01

    This study investigated the effect of CO2 laser irradiation on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement (GIC) or composite resin (CR) restorations. 40 dental blocks were divided into 4 groups: G1 (negative control): cavity preparation + adhesive restoration with CR; G2: (positive control) cavity preparation + GIC restoration; G3: equal to group 1 + CO2 laser with 6 J/cm2; G4: equal to group 2 + CO2 laser. The blocks were submitted to thermal and pH cycling. Dental demineralization around restorations was quantified using microhardness analyses and Light-Induced Fluorescence (QLF). The groups showed no significant differences in mineral loss at depths between 20 μm and 40 μm. At 60 μm, G2 and G3 ≠ G1, but G4 = G1, G2 and G3. At 80 μm, G4 ≠ G1, and at 100 μm, G4 = G2 = G1. At 140 and 220 μm, G2, G3, and G4 = G1. The averages obtained using QFL in groups 1, 2, 3, and 4 were 0.637, 0.162, 0.095, and 0.048, respectively. QLF and microhardness analyses showed that CO2 laser irradiation reduced mineral loss around the CR restorations but that it did not increase the anticariogenic effect of GIC restorations. PMID:26347900

  16. The Efficacy of Noncontingent Escape for Decreasing Children's Disruptive Behavior during Restorative Dental Treatment

    ERIC Educational Resources Information Center

    O'Callaghan, Patrick M.; Allen, Keith D.; Powell, Shawn; Salama, Fouad

    2006-01-01

    We evaluated the effectiveness of a dentist-implemented behavioral intervention in which brief escape from dental treatment was provided on a regular basis, independent of the child's behavior. Within a multiple baseline design across subjects, 5 children, ages 4 to 7 years, were provided with temporary escape from dental treatment on a fixed-time…

  17. Fracture resistance of endodontically treated teeth restored with indirect composite inlay and onlay restorations – An in vitro study

    PubMed Central

    Alshiddi, Ibraheem F.; Aljinbaz, Amjad

    2015-01-01

    Objective The purpose of this in vitro study was to evaluate and compare the fracture resistance and fracture mode of extensive indirect inlay and onlay composite resin restorations performed for endodontically treated premolars. Materials and methods A total of 55 extracted maxillary premolars were randomly divided into four groups. The first group (n = 15) remained untreated to serve as a positive control; the second group (n = 15) was endodontically treated with inlay cavities prepared and restored with indirect composite inlay restorations; the third group (n = 15) was also endodontically treated with onlay cavities prepared and restored with indirect composite onlay restorations; and the fourth group (n = 10) was endodontically treated with mesio-occlusodistal (MOD) cavities prepared and left unrestored to serve as negative controls. Dual cure indirect composite resin was used to fabricate the inlay and onlay restorations performed for the second and third groups, respectively. All teeth were subjected to compressive axial loading test using a metal ball (6 mm in diameter) in a universal testing machine (Instron 1195) with a cross-head speed of 0.5 mm/min until a fracture occurred. Statistical analysis of fracture resistance and fracture mode were performed with analysis of variance (ANOVA) (α = 0.05) and Kruskal–Wallis (α = 0.05) tests, respectively. Results For the four treatment groups, the mean fracture resistance values were 1326.9 N, 1500.1 N, 1006.1 N, and 702.7 N, respectively. Statistical analyses showed no significant differences between the mean fracture resistance of the intact tooth group and the inlay restoration group (p > 0.05), while significant differences were observed between the mean fracture resistance of all the other groups (p < 0.05). The Kruskal–Wallis test showed statistically significant differences between the fracture modes of the four groups. Conclusion Within the limitations of this study

  18. Achieving optimal aesthetics for direct and indirect restorations with microhybrid composite resins.

    PubMed

    Okuda, Wynn H

    2005-04-01

    In aesthetic dentistry, material science has played a key role in the development of natural-appearing restorations. Despite the progress, there have been challenges in achieving a harmonious integration of direct and indirect posterior restorations. Although porcelain restorations provide natural aesthetics, ceramics cannot be applied via direct techniques. Consequently, composite resins are valuable alternatives for conservative posterior restorations. In addition, because of their differing physical and optical properties, optimal aesthetic blending with porcelain and resin cannot be routinely achieved. This article explores the potential of composite resins as a direct and indirect restorative option in achieving the most favorable natural blend in the posterior region. PMID:15974036

  19. In vitro performance of Class I and II composite restorations: a literature review on nondestructive laboratory trials--part I.

    PubMed

    Dietschi, D; Argente, A; Krejci, I; Mandikos, M

    2013-01-01

    Posterior adhesive restorations are a basic procedure in general dental practices, but their application remains poorly standardized as a result of the number of available options. An abundant number of study hypotheses corresponding to almost unlimited combinations of preparation techniques, adhesive procedures, restorative options, and materials have been described in the literature and submitted to various evaluation protocols. A literature review was thus conducted on adhesive Class I and II restorations and nondestructive in vitro tests using the PubMed/Medline database for the 1995-2010 period. The first part of this review discusses the selected literature related to photoelasticity, finite element analysis (FEM), and microleakage protocols. Based on the aforementioned evaluation methods, the following parameters proved influential: cavity dimensions and design, activation mode (light or chemical), type of curing light, layering technique, and composite structure or physical characteristics. Photoelasticity has various limitations and has been largely (and advantageously) replaced by the FEM technique. The results of microleakage studies proved to be highly inconsistent, and the further use of this technique should be strictly limited. Other study protocols for adhesive Class II restorations were also reviewed and will be addressed in part II of this article, together with a tentative relevance hierarchy of selected in vitro methods. PMID:23738673

  20. Relief hologram replication using a dental composite as an embossing tool

    NASA Astrophysics Data System (ADS)

    Savić Šević, Svetlana; Pantelić, Dejan

    2005-04-01

    A simplified method for holographic embossing tool production is presented. Surface relief diffraction gratings are holographically recorded in pullulan sensitized with ammonium dichromate (DCP). The surface structure is copied into dental photopolymer composite by direct contact and subsequent photo-polymerization. It was found that arbitrary surface micropattern can be replicated. Due to its excellent mechanical and thermal properties, micro-patterned dental composite can be further used as an embossing tool for mass production of holograms.

  1. Application of color image processing and low-coherent optical computer tomography in evaluation of adhesive interfaces of dental restorations

    NASA Astrophysics Data System (ADS)

    Bessudnova, Nadezda O.; Shlyapnikova, Olga A.; Venig, Sergey B.; Genina, Elina A.; Sadovnikov, Alexandr V.

    2015-03-01

    Durability of bonded interfaces between dentin and a polymer material in resin-based composite restorations remains a clinical dentistry challenge. In the present study the evolution of bonded interfaces in biological active environment is estimated in vivo. A novel in vivo method of visual diagnostics that involves digital processing of color images of composite restorations and allows the evaluation of adhesive interface quality over time, has been developed and tested on a group of volunteers. However, the application of the method is limited to the analysis of superficial adhesive interfaces. Low-coherent optical computer tomography (OCT) has been tested as a powerful non-invasive tool for in vivo, in situ clinical diagnostics of adhesive interfaces over time. In the long-term perspective adhesive interface monitoring using standard methods of clinical diagnostics along with colour image analysis and OCT could make it possible to objectivise and prognosticate the clinical longevity of composite resin-based restorations with adhesive interfaces.

  2. Whisker-reinforced heat-cured dental resin composites: effects of filler level and heat-cure temperature and time.

    PubMed

    Xu, H H

    2000-06-01

    Currently available dental resin composites are inadequate for use in large stress-bearing crown and multiple-unit restorations. The aim of this study was to reinforce heat-cured composites with ceramic whiskers. It was hypothesized that whiskers substantially strengthen heat-cured composites. It was further hypothesized that whisker filler level and heat-cure temperature and time significantly influence composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers for improved retention in the matrix. The whisker filler mass fraction was varied from 0% to 79%, the heat-cure temperature from 80 degrees C to 180 degrees C, and cure time from 10 min to 24 hrs. Flexural strength, work-of-fracture, and fracture toughness of the composites were measured, and specimen fracture surfaces were examined with scanning electron microscopy. Filler level had a significant effect on composite properties. The whisker composite with 70% filler level had a flexural strength in MPa (mean +/- SD; n = 6) of 248 +/- 23, significantly higher than 120 +/- 16 of an inlay/onlay composite control and 123 +/- 21 of a prosthetic composite control (Tukey's multiple comparison test; family confidence coefficient = 0.95). Heat-cure time also played a significant role. At 120 degrees C, the strength of composite cured for 10 min was 178 +/- 17, lower than 236 +/- 14 of composite cured for 3 hrs. The strength of whisker composite did not degrade after water-aging for 100 d. In conclusion, heat-cured composites were substantially reinforced with whiskers. The reinforcement mechanisms appeared to be whiskers bridging and resisting cracks. The strength and fracture toughness of whisker composite were nearly twice those of currently available inlay/onlay and prosthetic composites. PMID:10890718

  3. Quantification of organic eluates from polymerized resin-based dental restorative materials by use of GC/MS.

    PubMed

    Michelsen, Vibeke Barman; Moe, Grete; Skålevik, Rita; Jensen, Einar; Lygre, Henning

    2007-05-01

    Residual monomers, additives and degradation products from resin-based dental restorative materials eluted into the oral cavity may influence the biocompatibility of these materials. Emphasis has been placed on studies addressing cytotoxic, genotoxic and estrogenic potential of these substances. A prerequisite for analyzing the potential of exposure to eluted compounds from dental materials is reliable quantification methods, both real time and accelerated measurements. The purpose of the present study was to quantify nine eluates; 2-hydroxyethyl methacrylate (HEMA), hydroquinone monomethyl ether (MEHQ), camphorquinone (CQ), butylated hydroxytoluene (BHT), ethyl 4-(dimethylamino)benzoate (DMABEE), triethylene glycoldimethacrylate (TEGDMA), trimethylolpropane trimethacrylate (TMPTMA), oxybenzone (HMBP) and drometrizole (TIN P) leaching from specimens of four commonly used resin-based dental materials in ethanol and an aqueous solution. All analyses were performed by use of GC/MS, each component was quantified separately and the results presented in microg mm(-2). This study has shown that elution from various materials differs significantly, not only in the types of eluates, but also regarding amounts of total and of single components. A high amount of HMBP, a UV stabilizer with potential estrogenic activity, was detected from one material in both solutions. PMID:17127109

  4. Microleakage in Class II composite restorations with margins below the CEJ: In vitro evaluation of different restorative techniques

    PubMed Central

    Chiesa, Marco; Scribante, Andrea; Mekler, Jenia; Colombo, Marco

    2013-01-01

    Objectives: The purpose of this in vitro study was to evaluate the microleakage in “deep” Class II composite restorations with gingival cavosurface margin below the CEJ (cemento-enamel junction) and restored with different techniques. Study Design: Fifty human teeth were used. In each tooth two standardized Class II slot cavities (on mesial and on distal surfaces) were prepared: the buccolingual extension of the cavities was 4 mm; the gingival wall was located in dentin/cementum (2 mm beyond the CEJ). The prepared teeth were randomly assigned to 5 experimental groups (of 10 specimens and 20 cavities each) and restored. Group 1: Filtek TM Supreme XTE Flowable (3MESPE) + Universal Filtek Supreme XTE (3MESPE), Group 2: GrandioSO Heavy Flow (Voco) + GrandioSo (Voco), Group 3: SDR™ (Dentsply Caulk) + Esthet-X® HD (Dentsply Caulk), Group 4: SonicFill (Kerr), Group 5: Grandio (Voco). After thermocycling, the specimens were immersed in a 0.5% basic fuchsine dye solution and incubated at 37°C for 24 hours. The teeth were subsequently sectioned mesiodistally. All specimens were examined at 25× in a stereomicroscope and standardized digital images were obtained. Dye penetration was measured from gingival margins. Results: The results demonstrated no significant leakage differences between Group 4 and Group 5, that both showed significantly higher frequency distribution of Score 0. Group 2 and Group 3 showed a significant prevalence of Score 1, whereas Group 1 showed significantly higher frequency of Score 2. Conclusions: None of the restorative techniques tested completely eliminated microleakage dye penetration in dentin margins; marginal adaptation in Class II composite restorations with gingival wall below the CEJ varied in both substrates and from different restorative techniques used. Key words:Microleakage, Class II composite restorations, CEJ. PMID:23722121

  5. Calculation of optical properties of dental composites as a basis for determining color impression and penetration depth of laser light

    NASA Astrophysics Data System (ADS)

    Weniger, Kirsten K.; Muller, Gerhard J.

    2005-03-01

    In order to achieve esthetic dental restorations, there should be no visible difference between restorative material and treated teeth. This requires a match of the optical properties of both restorative material and natural teeth. These optical properties are determined by absorption and scattering of light emerging not only on the surface but also inside the material. Investigating different dental composites in several shades, a method has been developed to calculate the optical parameters absorption coefficient μa, scattering coefficient μs, anisotropy factor g and reduced scattering coefficient μs'. The method includes sample preparation and measurements of transmittance and reflectance in an integrating sphere spectrometer, followed by inverse Monte Carlo simulations. Determination of optical properties is more precise and comprehensive than with the previously used Kubelka Munk theory because scattering can be looked at separated into pure scattering with the scattering coefficient μs and its direction with the anisotropy factor g. Moreover the use of the inverse Monte Carlo simulation not only minimizes systematic errors and considers the scattering phase function, but also takes into account the measuring geometry. The compilation of a data pool of optical parameters now enables the application of further calculation models as a basis for optimization of the composition of new materials. For example, a prediction of the general color impression for multiple layers can be carried out as well as the calculation of the wavelength dependent penetration depths of light with regard to photo polymerization. Further applications are possible in the area of laser ablation.

  6. Marginal bacterial leakage and pulp reactions in Class II composite resin restorations in vivo.

    PubMed

    Lundin, S A; Norén, J G; Warfvinge, J

    1990-01-01

    The presence of stainable bacteria under restorations and pulp reactions in 36 teeth restored in vivo with a modified Class II composite resin restoration with two different dentine treatment techniques were studied on three separate follow-up occasions (1-3, 7-10 and 28-32 days). Half of the cavities showed stainable bacteria at the cavity margins and bottoms. Teeth restored with method A (Gluma/Occlusin) showed significantly fewer restorations with stainable bacteria then teeth restored with method B (Life/Occlusin) (p less than 0.05). Significantly more restorations with detectable bacteria were found after 28-32 days and restorative method B (p less than 0.05). There were no differences in occurrence and grade of pulp inflammation for the different dentine treatment techniques and time periods. PMID:2124006

  7. Forensic or archaeological issue: is chemical analysis of dental restorations helpful in assessing time since death and identification of skeletonized human remains?

    PubMed

    Zelic, Ksenija; Djonic, Danijela; Neskovic, Olivera; Stoiljkovic, Milovan; Nikolic, Slobodan; Zivkovic, Vladimir; Djuric, Marija

    2013-09-01

    In 2011, small mass grave with completely skeletonized remains was discovered in Belgrade suburb. An eyewitness claimed that skeletons belonged to German soldiers killed in WWII. Anthropologists were engaged to investigate whether the skeletal remains correspond to the indicated German group or represent more recent case requiring court trial. Numerous dental restorations were noticed. Owing to the fact that different dental materials were used in dental practice at certain times, the aim of this study was to explore whether analysis of dental restorations could help in identification and estimation of time since death. Inductively coupled plasma optical emission spectrometry revealed that dental fillings corresponded to copper amalgam, conventional silver amalgam, silicophosphate cement, and zinc phosphate cement. Chemical results combined with anthropological and historical facts suggest that the individuals lived before the 1960s in country with well-developed dental service at that time. Therefore, chemical analysis of dental fillings was useful to distinguish between skeletal remains that are too old to be of forensic interest and the remains relevant to legal investigations. PMID:23866008

  8. Measurement of J-integral in CAD/CAM dental ceramics and composite resin by digital image correlation.

    PubMed

    Jiang, Yanxia; Akkus, Anna; Roperto, Renato; Akkus, Ozan; Li, Bo; Lang, Lisa; Teich, Sorin

    2016-09-01

    Ceramic and composite resin blocks for CAD/CAM machining of dental restorations are becoming more common. The sample sizes affordable by these blocks are smaller than ideal for stress intensity factor (SIF) based tests. The J-integral measurement calls for full field strain measurement, making it challenging to conduct. Accordingly, the J-integral values of dental restoration materials used in CAD/CAM restorations have not been reported to date. Digital image correlation (DIC) provides full field strain maps, making it possible to calculate the J-integral value. The aim of this study was to measure the J-integral value for CAD/CAM restorative materials. Four types of materials (sintered IPS E-MAX CAD, non-sintered IPS E-MAX CAD, Vita Mark II and Paradigm MZ100) were used to prepare beam samples for three-point bending tests. J-integrals were calculated for different integral path size and locations with respect to the crack tip. J-integral at path 1 for each material was 1.26±0.31×10(-4)MPam for MZ 100, 0.59±0.28×10(-4)MPam for sintered E-MAX, 0.19±0.07×10(-4)MPam for VM II, and 0.21±0.05×10(-4)MPam for non-sintered E-MAX. There were no significant differences between different integral path size, except for the non-sintered E-MAX group. J-integral paths of non-sintered E-MAX located within 42% of the height of the sample provided consistent values whereas outside this range resulted in lower J-integral values. Moreover, no significant difference was found among different integral path locations. The critical SIF was calculated from J-integral (KJ) along with geometry derived SIF values (KI). KI values were comparable with KJ and geometry based SIF values obtained from literature. Therefore, DIC derived J-integral is a reliable way to assess the fracture toughness of small sized specimens for dental CAD/CAM restorative materials; however, with caution applied to the selection of J-integral path. PMID:27232827

  9. Failure Rate of Direct High-Viscosity Glass-Ionomer Versus Hybrid Resin Composite Restorations in Posterior Permanent Teeth - a Systematic Review

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Purpose Traditionally, resin composite restorations are claimed by reviews of the dental literature as being superior to glass-ionomer fillings in terms of restoration failures in posterior permanent teeth. The aim of this systematic review is to answer the clinical question, whether conventional high-viscosity glass-ionomer restorations, in patients with single and/or multi-surface cavities in posterior permanent teeth, have indeed a higher failure rate than direct hybrid resin composite restorations. Methods Eight databases were searched until December 02, 2013. Trials were assessed for bias risks, in-between datasets heterogeneity and statistical sample size power. Effects sizes were computed and statistically compared. A total of 55 citations were identified through systematic literature search. From these, 46 were excluded. No trials related to high-viscosity glass-ionomers versus resin composite restorations for direct head-to-head comparison were found. Three trials related to high-viscosity glass-ionomers versus amalgam and three trials related to resin composite versus amalgam restorations could be included for adjusted indirect comparison, only. Results The available evidence suggests no difference in the failure rates between both types of restoration beyond the play of chance, is limited by lack of head-to-head comparisons and an insufficient number of trials, as well as by high bias and in-between-dataset heterogeneity risk. The current clinical evidence needs to be regarded as too poor in order to justify superiority claims regarding the failure rates of both restoration types. Sufficiently large-sized, parallel-group, randomised control trials with high internal validity are needed, in order to justify any clinically meaningful judgment to this topic. PMID:26962372

  10. A mechanism on why slower polymerization of a dental composite produces lower contraction stress.

    PubMed

    Feng, L; Suh, B I

    2006-07-01

    It has been well documented that the rate of polymerization of a dental composite often affects its polymerization contraction stress. In most cases, a slower cure produces a lower stress. To investigate the mechanism behind this, we prepared an unfilled dimethacrylate resin sample and photocured it using two light irradiances, both with the same total irradiation energy. We measured the polymerization-induced shrinkage from the unbonded surface of a class I restoration, contraction stress, extent of polymerization, and flexural modulus. The resin specimens cured under the two irradiances achieved the same extent of polymerization and developed an identical amount of shrinkage from the unbonded surface. But those cured under the lower irradiance possessed a lower contraction stress and a lower flexural modulus than those cured under the higher irradiance. We demonstrated that the stress level did not respond to the extent of viscous flow of the curing resin because the slower polymerization did not produce more shrinkage from the unbonded surface. Instead, the lower stress is likely due to a lower modulus of the cured resin. To explain why the cured resin with an identical extent of polymerization can have different moduli, we proposed that slower polymerization produces a higher level of structural inhomogeneity, which reduces the rigidity of the cured resin. PMID:16470813

  11. The efficacy of noncontingent escape for decreasing children's disruptive behavior during restorative dental treatment.

    PubMed

    O'Callaghan, Patrick M; Allen, Keith D; Powell, Shawn; Salama, Fouad

    2006-01-01

    We evaluated the effectiveness of a dentist-implemented behavioral intervention in which brief escape from dental treatment was provided on a regular basis, independent of the child's behavior. Within a multiple baseline design across subjects, 5 children, ages 4 to 7 years, were provided with temporary escape from dental treatment on a fixed-time schedule. The intervals were signaled by an electronic timer worn by the dentist. Clinically significant reductions were observed in physically disruptive behavior across all 5 children with the introduction of noncontingent escape, and verbally disruptive behavior was markedly reduced in 4 of the 5 children. In addition, the dental staff s use of physical restraint was reduced to near zero across all 5 children. The research extends the literature in both clinical dentistry and in applied behavior analysis by demonstrating that a dentist can easily and effectively implement noncontingent reinforcement to produce clinically significant and socially important changes in children's health behavior. PMID:16813038

  12. Repair bond strength of restorative resin composite applied to fiber-reinforced composite substrate.

    PubMed

    Tezvergil, Arzu; Lassila, Lippo V J; Yli-Urpo, Antti; Vallittu, Pekka K

    2004-02-01

    Delamination or fracture of composite veneers can occur as a result of improper design of the fiber-reinforced composite (FRC) framework. This in vitro study tested the repair bond strength of restorative composite to aged FRC. The substrate was multiphase polymer matrix FRC (everStick) aged by boiling for 8 h and storing at 37 degrees C in water for 6 weeks. The aged substrate surfaces were wet-ground flat with 1200-grit silicon carbide paper and subjected randomly to 5 different surface treatments: 1) An adhesion primer (Composite Activator) and resin (CA), 2) Silane (EspeSil) and resin (SIL-MP), 3) Silane, adhesive primer, and resin (Clearfil Repair) (CF), 4) Air particle-abrading (CoJet), silane, and resin (CJ-SIL-MP), 5) Resin (Scotchbond Multipurpose Resin) only as control (MP). Restorative composite resin (Z250) was added to the substrate in 2 mm layer increments and light-cured. Subsequently, every surface treatment group was divided into 2 subgroups of 12 specimens each. The specimens were either 48 h water-stored or thermocycled (6000 x 5-55 degrees C). The shear bond strengths of composite resin to FRC were measured at a crosshead speed of 1.0 mm/min. The data were analyzed by ANOVA for factors 'treatment type' and 'storage condition'; Tukey's post-hoc tests and Weibull analysis were performed. ANOVA showed a significant difference as a function of surface treatment (P<0.05) and storage condition (P<0.05). The CJ-SIL-MP group showed highest bond strength and Weibull modulus after thermocycling. Repair of multiphase polymer matrix FRC may show reliable bond strength when silane treatment is used along with air-particle abrading. PMID:15124783

  13. Cervical enamel crazings associated with occluso-proximal composite restorations in posterior teeth.

    PubMed

    Marzouk, M A; Ross, J A

    1989-12-01

    Cervical enamel crazing lines were counted after preparing MODBL preparations in freshly extracted maxillary premolars. The teeth were restored with composite onlays. One-third of the restored teeth were left as is. In the second third MD intra-composite staples were prepared. The staples were prepared at 10, 20 and 30 minutes and 24-hour intervals. The craze lines were counted pre- and post-restoratively. Intra-composite staples reduced craze lines substantially. There were no statistical differences between MD and MD-BL staples. Thirty minutes proved to be the maximum time to prepare these staples to have a reducing effect on the number of craze lines. PMID:2700640

  14. Use of a compact fiber optic spectrometer for spectral feedback during the laser ablation of dental hard tissues and restorative materials

    NASA Astrophysics Data System (ADS)

    Cheng, Joyce Y.; Fan, Kenneth; Fried, Daniel

    2006-02-01

    One perceived disadvantage of caries removal using lasers is the loss of the tactile feedback associated with the handpiece. However, alternative methods of acoustic and optical feedback become available with the laser that can be exploited to provide information about the chemical composition of the material ablated, the ablation efficiency and rate, the depth of the incision, and the surface and plume temperature during ablation. Such information can be used to increase the selectivity of ablation, avoid peripheral thermal damage and excessive heat deposition in the tooth, and provide a mechanism of robotic automation. The objective of this study was to test the hypothesis that a compact fiberoptic spectrometer could be used to differentiate between the ablation of sound and carious enamel and dentin and between dental hard tissues and composite. Sound and carious tooth surfaces along with composite restorative materials were scanned with λ=0.355, 2.79 and 9.3 μm laser pulses at irradiation intensities ranging from 0.5-100 J/cm2 and spectra were acquired from λ=250-900-nm using a compact fiber-optic spectrometer. Emission spectra varied markedly with the laser wavelength and pulse duration. Optical feedback was not successful in differentiating between sound and carious enamel and dentin even with the addition of various chromophores to carious lesion areas. However, the spectral feedback was successfully used to differentiate between composites and sound enamel and dentin enabling the selective removal of composite from tooth surfaces using a computer controlled λ=9.3-μm pulsed CO II laser and scanning system.

  15. A 3-year randomized clinical trial evaluating two different bonded posterior restorations: Amalgam versus resin composite

    PubMed Central

    Kemaloglu, Hande; Pamir, Tijen; Tezel, Huseyin

    2016-01-01

    Objective: To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam. Materials and Methods: This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months. Results: Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3rd year, overall “Bravo” rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3rd year evaluation (P < 0.05). Conclusions: Within the limitation of this study, both resin composite and bonded amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities. PMID:27011734

  16. Longevity of posterior composite restorations: a systematic review and meta-analysis.

    PubMed

    Opdam, N J M; van de Sande, F H; Bronkhorst, E; Cenci, M S; Bottenberg, P; Pallesen, U; Gaengler, P; Lindberg, A; Huysmans, M C D N J M; van Dijken, J W

    2014-10-01

    The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years' follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces. PMID:25048250

  17. Measurement of the fluorescence of restorative dental materials using a 655-nm diode laser

    NASA Astrophysics Data System (ADS)

    Zanin, Fatima A. A.; Souza-Campos, Dilma H.; Zanin, Sissi; Brugnera, Aldo, Jr.; Pecora, Jesus D.; Pinheiro, Antonio L. B.; Harari, Sonia

    2001-04-01

    The aim of this study was to determine the level of fluorescence of seven restorative materials using 655 nm diode laser. The laser fluorescence system has ben used as an auxiliary method for the detection of carious lesions. This new diagnostic method increases information which are important for the choice of treatment by the Dentist. The characteristic of restorative materials and sealers interferes in the values obtained by the apparatus during the detection of secondary carious lesions. The optical properties of each biological tissue or material are related to the interaction with the laser beam. Aware of that, the fluorescence of healthy dentin and enamel is 0-15, the authors determined the fluorescence of seven restorative materials with 10 teeth in each group. The laser reading scale differed according to the materia, ranging from 1 to 22 with several materials, for example the sealer without inorganic filler and the glass ionomer, showing fluorescence values similar to carious enamel which interferes with the readings around the restorations resulting in a false positive. Knowledge of restoration material fluorescence can aid in the detection of secondary carious lesions around the restorations.

  18. Knowledge and Awareness among Parents and General Dental Practitioners regarding Rehabilitation with Full Coverage Restoration in Children: A Multi-centric Trial

    PubMed Central

    Saroj, Gyanendra; Sharma, Swati; Gupta, Basant

    2016-01-01

    ABSTRACT Aims: The aim of this study was to evaluate the knowledge and awareness among parents and general dental practitioners regarding rehabilitation with full coverage restoration in children following pulp therapy. Materials and methods: A multiple choice questionnaire was given to 1,000 parents and 400 general practitioners in this multicentric trial. The questionnaire assessed their beliefs, knowledge regarding care of primary teeth, assessment of treating children, and knowledge regarding importance of primary teeth. All the questionnaires were then compiled and statistically analyzed using Statistical Package for Social Sciences (SPSS) software. Results and discussion: 53% parents did not know the importance of primary teeth and 73% parents also thought that no treatment is possible for pulpally involved primary teeth. 20% parents believed that root canal treatment can be possible for children and only 10% knew about full coverage restorations. 40% of the general dentists felt that the best treatment in the case of primary necrotic teeth is extraction and only 13% knew about stainless steel crowns. 62% of general dental practitioners pointed out patients’ noninterest in providing crowns whereas 68% parents reported non-information by dentists. Conclusion: Both parents and general dental practitioners have incomplete and inadequate knowledge regarding full coverage restorations, and we need to improve the knowledge and dental awareness of the parents and the general dental practitioners. How to cite this article: Moda A, Saroj G, Sharma S, Gupta B. Knowledge and Awareness among Parents and General Dental Practitioners regarding Rehabilitation with Full Coverage Restoration in Children: A Multi-centric Trial. Int J Clin Pediatr Dent 2016;9(2):177-180. PMID:27365944

  19. Development of dental composites with reactive fillers that promote precipitation of antibacterial-hydroxyapatite layers.

    PubMed

    Aljabo, Anas; Abou Neel, Ensanya A; Knowles, Jonathan C; Young, Anne M

    2016-03-01

    The study aim was to develop light-curable, high strength dental composites that would release calcium phosphate and chlorhexidine (CHX) but additionally promote surface hydroxyapatite/CHX co-precipitation in simulated body fluid (SBF). 80 wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10 wt.% CHX and 0, 10, 20 or 40 wt.% reactive mono- and tricalcium phosphate (CaP). Surface hydroxyapatite layer thickness/coverage from SEM images, Ca/Si ratio from EDX and hydroxyapatite Raman peak intensities were all proportional to both time in SBF and CaP wt.% in the filler. Hydroxyapatite was, however, difficult to detect by XRD until 4 weeks. XRD peak width and SEM images suggested this was due to the very small size (~10 nm) of the hydroxyapatite crystallites. Precipitate mass at 12 weeks was 22 wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7 wt.% of the specimen. Early diffusion controlled CHX release, assessed by UV spectrometry, was proportional to CaP and twice as fast in water compared with SBF. After 1 week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12 weeks CHX formed 5 to 15% of the HA layer with 10 to 40 wt.% CaP respectively. Despite linear decline of strength and modulus in 4 weeks from 160 to 101 MPa and 4 to 2.4 GPa, respectively, upon raising CaP content, all values were still within the range expected for commercial composites. The high strength, hydroxyapatite precipitation and surface antibacterial accumulation should reduce tooth restoration failure due to fracture, aid demineralised dentine repair and prevent subsurface carious disease respectively. PMID:26706532

  20. Direct Restorative Treatment of Missing Maxillary Laterals with Composite Laminate Veneer: A Case Report

    PubMed Central

    Bagis, Bora; Aydoğan, Elif; Bagis, Yildirim H.

    2008-01-01

    This clinical report describes a direct composite laminate veneer restoration of the maxillary anterior teeth in one chair time to produce a better esthetic appearance in a patient with diastemata and missing laterals. PMID:19088889

  1. Effect of diamond burs on process and damage involving in vitro dental resurfacing of a restorative porcelain

    NASA Astrophysics Data System (ADS)

    Yin, Ling; Han, Yi-Gang; Song, Xiao-Fei; Wang, Hui

    2007-09-01

    This work reports on the effect of diamond burs with coarse, medium and fine grit sizes and nickel or chromium coatings on in vitro dental resurfacing of a restorative porcelain. Process parameters such as tangential and normal forces, surface roughness, surface damage and morphology were studied as a function of removal rate using the different burs. At the lower removal rate, the differences for both the tangential and the normal forces were not significant among the coarse, medium and fine burs. However, when the porcelain was removed at the higher removal rate, both the tangential and the normal forces were markedly higher using the fine bur than those using the medium and coarse burs. Surface roughness values in terms of arithmetic mean and maximum roughness decreased significantly with a decrease in diamond grit size. The scale of surface damage in the form of brittle fracture decreased, and more transitions from brittle removal to ductile flow were observed when using finer grit diamond burs. In a comparison of the diamond bur topographies before and after dental finishing, it was found that minimal wear occurred on the nickel-coated coarse diamond bur, while minor abrasive wear occurred on the nickel-coated medium and chromium-coated fine burs.

  2. Quantitative evaluation of proximal contacts in posterior composite restorations. Part I. Methodology.

    PubMed

    Wang, J C; Hong, J M

    1989-07-01

    An in vivo method of quantitative measuring intertooth distance before and after placement of a Class 2 composite resin restoration has been developed. A Kaman Sciences KD-2611 non-contact displacement measuring system with a 1 U unshield sensor, based upon the variable resistance of eddy current, was used for the intraoral measurement. Quantitative evaluation of proximal wear, therefore, can be made preoperatively, postoperatively, and at subsequent recall interval for posterior composite resin restorations. PMID:2810447

  3. Fracture resistance of endodontically treated teeth restored with a bulkfill flowable material and a resin composite

    PubMed Central

    Isufi, Almira; Plotino, Gianluca; Grande, Nicola Maria; Ioppolo, Pietro; Testarelli, Luca; Bedini, Rossella; Al-Sudani, Dina; Gambarini, Gianluca

    2016-01-01

    Summary Aim To determine and compare the fracture resistance of endodontically treated teeth restored with a bulk fill flowable material (SDR) and a traditional resin composite. Methods Thirty maxillary and 30 mandibular first molars were selected based on similar dimensions. After cleaning, shaping and filling of the root canals and adhesive procedures, specimens were assigned to 3 subgroups for each tooth type (n=10): Group A: control group, including intact teeth; Group B: access cavities were restored with a traditional resin composite (EsthetX; Dentsply-Italy, Rome, Italy); Group C: access cavities were restored with a bulk fill flowable composite (SDR; Dentsply-Italy), except 1.5 mm layer of the occlusal surface that was restored with the same resin composite as Group B. The specimens were subjected to compressive force in a material static-testing machine until fracture occurred, the maximum fracture load of the specimens was measured (N) and the type of fracture was recorded as favorable or unfavorable. Data were statistically analyzed with one-way analysis of variance (ANOVA) and Bonferroni tests (P<0.05). Results No statistically significant differences were found among groups (P<0.05). Fracture resistance of endodontically treated teeth restored with a traditional resin composite and with a bulk fill flowable composite (SDR) was similar in both maxillary and mandibular molars and showed no significant decrease in fracture resistance compared to intact specimens. Conclusions No significant difference was observed in the mechanical fracture resistance of endodontically treated molars restored with traditional resin composite restorations compared to bulk fill flowable composite restorations. PMID:27486505

  4. Multilevel modelling of clustered grouped survival data using Cox regression model: an application to ART dental restorations.

    PubMed

    Wong, May C M; Lam, K F; Lo, Edward C M

    2006-02-15

    In some controlled clinical trials in dental research, multiple failure time data from the same patient are frequently observed that result in clustered multiple failure time. Moreover, the treatments are often delivered by more than one operator and thus the multiple failure times are clustered according to a multilevel structure when the operator effects are assumed to be random. In practice, it is often too expensive or even impossible to monitor the study subjects continuously, but they are examined periodically at some regular pre-scheduled visits. Hence, discrete or grouped clustered failure time data are collected. The aim of this paper is to illustrate the use of the Monte Carlo Markov chain (MCMC) approach and non-informative prior in a Bayesian framework to mimic the maximum likelihood (ML) estimation in a frequentist approach in multilevel modelling of clustered grouped survival data. A three-level model with additive variance components model for the random effects is considered in this paper. Both the grouped proportional hazards model and the dynamic logistic regression model are used. The approximate intra-cluster correlation of the log failure times can be estimated when the grouped proportional hazards model is used. The statistical package WinBUGS is adopted to estimate the parameter of interest based on the MCMC method. The models and method are applied to a data set obtained from a prospective clinical study on a cohort of Chinese school children that atraumatic restorative treatment (ART) restorations were placed on permanent teeth with carious lesions. Altogether 284 ART restorations were placed by five dentists and clinical status of the ART restorations was evaluated annually for 6 years after placement, thus clustered grouped failure times of the restorations were recorded. Results based on the grouped proportional hazards model revealed that clustering effect among the log failure times of the different restorations from the same child was

  5. Recent advances in dental optics - Part I: 3D intraoral scanners for restorative dentistry

    NASA Astrophysics Data System (ADS)

    Logozzo, Silvia; Zanetti, Elisabetta M.; Franceschini, Giordano; Kilpelä, Ari; Mäkynen, Anssi

    2014-03-01

    Intra-oral scanning technology is a very fast-growing field in dentistry since it responds to the need of an accurate three-dimensional mapping of the mouth, as required in a large number of procedures such as restorative dentistry and orthodontics. Nowadays, more than 10 intra-oral scanning devices for restorative dentistry have been developed all over the world even if only some of those devices are currently available on the market. All the existing intraoral scanners try to face with problems and disadvantages of traditional impression fabrication process and are based on different non-contact optical technologies and principles. The aim of this publication is to provide an extensive review of existing intraoral scanners for restorative dentistry evaluating their working principles, features and performances.

  6. 56-month clinical performance of Class I and II resin composite restorations

    PubMed Central

    PAZINATTO, Flavia Bittencourt; GIONORDOLI NETO, Ranulfo; WANG, Linda; MONDELLI, José; MONDELLI, Rafael Francisco Lia; NAVARRO, Maria Fidela de Lima

    2012-01-01

    Objective This study evaluated the 56-month clinical performance of Class I and II resin composite restorations. Filtek P60 was compared with Filtek Z250, which are both indicated for posterior restorations but differ in terms of handling characteristics. The null hypothesis tested was that there is no difference in the clinical performance of the two resin composites in posterior teeth. Material and Methods Thirty-three patients were treated by the same operator, who prepared 48 Class I and 42 Class II cavities, which were restored with Single Bond/Filtek Z250 or Single Bond/Filtek P60 restorative systems. Restorations were evaluated by two independent examiners at baseline and after 56 months, using the modified USPHS criteria. Data were analyzed statistically using Chi-square and Fisher's Exact tests (a=0.05). Results After 56 months, 25 patients (31 Class I and 36 Class II) were analyzed. A 3% failure rate occurred due to secondary caries and excessive loss of anatomic form for P60. For both restorative systems, there were no significant differences in secondary caries and postoperative sensitivity. However, significant changes were observed with respect to anatomic form, marginal discoloration, and marginal adaptation. Significant decreases in surface texture were observed exclusively for the Z250 restorations. Conclusions Both restorative systems can be used for posterior restorations and can be expected to perform well in the oral environment. PMID:22858698

  7. Dental composite resins: measuring the polymerization shrinkage using optical fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Ottevaere, H.; Tabak, M.; Chah, K.; Mégret, P.; Thienpont, H.

    2012-04-01

    Polymerization shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. As an alternative to conventional measurement methods, we propose optical fiber Bragg grating (FBG) based sensors to perform real-time strain and shrinkage measurements during the curing process of dental resin cements. We introduce a fully automated set-up to measure the Bragg wavelength shift of the FBG strain sensors and to accurately monitor the linear strain and shrinkage of dental resins during curing. Three different dental resin materials were studied in this work: matrix-filled BisGMA-based resins, glass ionomers and organic modified ceramics.

  8. Effects of Fiber-reinforced Composite Bases on Microleakage of Composite Restorations in Proximal Locations

    PubMed Central

    A, Tezvergil-Mutluay; P.K, Vallittu

    2014-01-01

    Objectives: The aim of this study was to evaluate the microleakage of direct restorative composite resin upon the addition of an intermediate glass fiber-reinforced composite (GFRC) layer of various fiber orientations between tooth and particulate filler composite resin (PFRC). Materials and Methods: Cavities were prepared both on the mesial and distal surfaces of sixty extracted human molars with one margin placed below and the other above the cementoenamel junction (CEJ). Teeth were assigned to five different groups. Four of the groups received a layer of semi-interpenetrating polymer network (semi-IPN) resin system impregnated E-glass GFRC at the bottom of the cavity: Group 1; unidirectional continuous GFRC (EVS) in buccolingual direction (EVS-BL), Group 2; EVS in mesiodistal direction (EVS-MD), Group 3; bidirectional woven GFRC (EVN), Group 4; multidirectional short GFRC (EXP-MLT), Group 5; PRFC only (control). After acid etching and priming of the cavities and insertion of GFRC layer with the adhesive resin (Scotchbond Multipurpose 3M-ESPE), the cavities were filled incrementally with PRFC (Filtek Z250, 3M-ESPE) and each layer was light cured for 20 s. After finishing and polishing, the restored teeth were water-stored for 24 h at 37 °C and then thermocycled for 6000 cycles between 5-55 °C, before immersion in 0.5 % basic fuchsin dye for 24 h. After sectioning by 3-5 sagittal cuts, each sequential section was imaged and digitally analyzed to determine the stain depth. Results: All GFRC groups in dentin revealed significantly lower microleakage compared to control (p<0.05). The orientation of FRC intermediate layer did not reveal significant differences in microleakage (p>0.05). The microleakeage in enamel was not different between the groups (p>0.05). Conclusion: Use of intermediate GFRC layer between tooth and PFRC could provide alternative method to minimize microleakage. Clinical Relevance: Use of GFRC intermediate layer underneath the particulate filler

  9. Evaluation of Marginal Integrity of Four Bulk-Fill Dental Composite Materials: In Vitro Study

    PubMed Central

    Orłowski, Mirosław; Tarczydło, Bożena; Chałas, Renata

    2015-01-01

    Objective. The aim of the study was to compare under in vitro conditions marginal sealing of 4 different bulk-fill materials composite restorations of class II. Methods. Comparative evaluation concerned 4 composites of a bulk-fill type: SonicFill, Tetric EvoCeram Bulk Fill, Filtek Bulk Fill, and SDR. The study used 30 third molars without caries. In each tooth 4 cavities of class II were prepared. The prepared tooth samples were placed in a 1% methylene blue solution for 24 h, and after that in each restoration the depth of dye penetration along the side walls was evaluated. Results. The highest rating (score 0, no dye penetration) was achieved by 93.33% of the restorations made of the SDR material, 90% of restorations of SonicFill system, 86.66% of restorations of the composite Filtek Bulk Fill, and 73.33% of restorations of the Tetric EvoCeram Bulk Fill. Conclusion. The performed study showed that bulk-fill flowable or sonic-activated flowable composite restorations have better marginal sealing (lack of discoloration) in comparison with bulk-fill paste-like composite. PMID:25874254

  10. Optical approach in characterizing dental biomaterials

    NASA Astrophysics Data System (ADS)

    Demoli, Nazif; Vučić, Zlatko; Milat, Ognjen; Gladić, Jadranko; Lovrić, Davorin; Pandurić, Vlatko; Marović, Danijela; Moguš-Milanković, Andrea; Ristić, Mira; Čalogović, Marina; Tarle, Zrinka

    2013-04-01

    The purpose of this paper is to present the current activities of a research collaborative program between three institutions from Zagreb (School of Dental Medicine, Institute of Physics, and Institute Ruđer Bo\\vsković). Within the scope of this program, it is planned to investigate and find guidelines for the refinement of the properties of dental biomaterials (DBs) and of procedures in restorative dental medicine. It is also planned to identify and model the dominant mechanisms which control polymerization of DBs. The materials to be investigated include methacrylate based composite resins, new composite materials with amorphous calcium phosphate, silorane based composite resins, glass-ionomer cements, and giomer.

  11. Rapid and non-destructive analysis of metallic dental restorations using X-ray fluorescence spectra and light-element sampling tools

    NASA Astrophysics Data System (ADS)

    Furuhashi, K.; Uo, M.; Kitagawa, Y.; Watari, F.

    2012-12-01

    IntroductionRecently, allergic diseases caused by dental metals have been increasing. Therefore, rapid and accurate analytical methods for the metal restorations in the oral cavities of patients are required. The purpose of this study was to develop a non-destructive extraction method for dental alloys, along with a subsequent, rapid and accurate elemental analysis. Materials and methodSamples were obtained by polishing the surfaces of metal restorations using a dental rotating tool with disposable buffs and polishing pastes. As materials for the analysis, three dental alloys were used. To compare the sampling and analysis efficiencies, two buffs and seven pastes were used. After polishing the surface of a metal restoration, the buff was analyzed using X-ray scanning analytical microscopy (XSAM). ResultsThe efficiency of the analysis was judged based on the sampling rate achieved and the absence of disturbing elements in the background in fluorescence X-ray spectra. The best results were obtained for the combination of TexMet as a buff with diamond as a paste. This combination produced a good collection efficiency and a plain background in the fluorescence X-ray spectra, resulting in a high precision of the analysis.

  12. Evaluation of surface roughness of different restorative composites after polishing using atomic force microscopy

    PubMed Central

    Kumari, C Meena; Bhat, K Manohar; Bansal, Rahul

    2016-01-01

    Introduction: Resin based composites are widely used aesthetic restorative materials in clinical restorative dentistry. The filler size and the percentage of fillers affects smooth surface, clinical durability, aesthetics, better optical properties, compatibility with natural enamel tissue, surface gloss, and preventing the discoloration of the restoration. The finishing and polishing of tooth-coloured restorations are necessary clinical steps for better aesthetics and longevity of restored teeth. Aim: In this study nano composites were chosen, because these contain nano particles which provide better overall composites features, including the quality of polished surface. The aim of this study was to evaluate the surface roughness of different newer posterior composites. Material and Method: Five commercially available posterior restorative composite were tested in this study. All the specimens were polished with shofu multi step polishing system. After polishing the samples were all analyzed by atomic force microscopy which is used to study surface topography and surface morphology of materials. Results: The values of surface roughness of each specimen were statistically analyzed using Kruskal Wallis ANOVA, and Pair wise comparisons by Mann-Whitney U test setting the statistical significance at p ≤ 0.05. Conclusion: Tetric Evo Ceram, Z350 exhibited less surface roughness compared to Ever X, Clearfil Majesty and Sure fil SDR. There was no statistical difference between groups regarding surface rough ness between groups. PMID:26957795

  13. Comparison of acceptance, preference and efficacy between pressure anesthesia and classical needle infiltration anesthesia for dental restorative procedures in adult patients

    PubMed Central

    Makade, Chetana Sachin; Shenoi, Pratima R; Gunwal, Mohit K

    2014-01-01

    Introduction: Intraoral local anesthesia is essential for delivering dental care. Needless devices have been developed to provide anesthesia without injections. Little controlled research is available on its use in dental restorative procedures in adult patients. The aims of this study were to compare adult patients acceptability and preference for needleless jet injection with classical local infiltration as well as to evaluate the efficacy of the needleless anesthesia. Materials and Methods: Twenty non fearful adults with no previous experience of dental anesthesia were studied using split-mouth design. The first procedure was performed with classical needle infiltration anesthesia. The same amount of anesthetic solution was administered using MADA jet needleless device in a second session one week later, during which a second dental restorative procedure was performed. Patients acceptance was assessed using Universal pain assessment tool while effectiveness was recorded using soft tissue anesthesia and pulpal anesthesia. Patients reported their preference for the anesthetic method at the third visit. The data was evaluated using chi square test and student's t-test. Results: Pressure anesthesia was more accepted and preferred by 70% of the patients than traditional needle anesthesia (20%). Both needle and pressure anesthesia was equally effective for carrying out the dental procedures. Conclusion: Patients experienced significantly less pain and fear (p<0.01) during anesthetic procedure with pressure anesthesia. However, for more invasive procedures needle anesthesia will be more effective. PMID:24778516

  14. Dentist and practice characteristics associated with restorative treatment of enamel caries in permanent teeth: multiple-regression modeling of observational clinical data from The National Dental PBRN

    PubMed Central

    Fellows, Jeffrey L; Gordan, Valeria V.; Gilbert, Gregg H.; Rindal, D. Brad; Qvist, Vibeke; Litaker, Mark S.; Benjamin, Paul; Flink, Håkan; Pihlstrom, Daniel J.; Johnson, Neil

    2014-01-01

    Purpose Current evidence in dentistry recommends non-surgical treatment to manage enamel caries lesions. However, surveyed practitioners report they would restore enamel lesions that are confined to the enamel. We used actual clinical data to evaluate patient, dentist, and practice characteristics associated with restoration of enamel caries, while accounting for other factors. Methods We combined data from a National Dental Practice-Based Research Network observational study of consecutive restorations placed in previously unrestored permanent tooth surfaces and practice/demographic data from 229 participating network dentists. Analysis of variance and logistic regression, using generalized estimating equations (GEE) and variable selection within blocks, were used to test the hypothesis that patient, dentist, and practice characteristics were associated with variations in enamel restorations of occlusal and proximal caries compared to dentin lesions, accounting for dentist and patient clustering. Results Network dentists from 5 regions placed 6,891 restorations involving occlusal and/or proximal caries lesions. Enamel restorations accounted for 16% of enrolled occlusal caries lesions and 6% of enrolled proximal caries lesions. Enamel occlusal restorations varied significantly (p<0.05) by patient age and race/ethnicity, dentist use of caries risk assessment, network region, and practice type. Enamel proximal restorations varied significantly (p<0.05) by dentist race/ethnicity, network region, and practice type. CLINICAL SIGNIFICANCE Identifying patient, dentist, and practice characteristics associated with enamel caries restorations can guide strategies to improve provider adherence to evidence-based clinical recommendations. PMID:25000667

  15. Effect of different adhesive strategies on the post-operative sensitivity of class I composite restorations

    PubMed Central

    Sancakli, Hande Sar; Yildiz, Esra; Bayrak, Isil; Ozel, Sevda

    2014-01-01

    Objective: To evaluate the post-operative sensitivity of occlusal restorations using different dentin adhesives performed by an undergraduate and a post-doctorate dentist. Materials and Methods: One hundred and eighty-eight molar occlusal restorations were placed in 39 patients (ages between 18 and 30) using 3 different kind of adhesive systems; Optibond FL (OBF), Clearfil Protect Bond (CPB), and iBond (IB) by a post-doctorate dentist or a fifth-year dental student according to the manufacturers’ instructions. Post-operative sensitivity to cold and air was evaluated using a Visual Analog Scale (VAS) after 24 hours, 30, 90, and 180 days. Data were analyzed using the Mann-Whitney U and Friedman tests (P < 0.05). Results: Post-operative sensitivity scores for OBF and CPB were higher for the dental student (P < 0.05), while IB scores did not differ statistical significantly according to the operator (P > 0.05). Conclusion: Operator skill and experience appears to play a role in determining the outcome of post-operative sensitivity of multi-step adhesive systems although the post-operative sensitivity was low. It is suggested that the less experienced clinicians (rather than experienced clinicians) should better use the self-etching dentin bonding systems with reduced application steps to minimize the potential risk of post-operative sensitivity of dental adhesives. PMID:24966741

  16. Sealing of adhesive systems in ferric sulfate-contaminated dentinal margins in class V composite resin restorations.

    PubMed

    Shadman, Niloofar; Farzin Ebrahimi, Shahram; Mollaie, Najmeh

    2016-01-01

    Background. Hemostatic agents are applied to prepare an isolated bleeding-free condition during dental treatments and can influence adhesive restorations. This study evaluated the effect of a hemostatic agent (ViscoStat) on microleakage of contaminated dentinal margin of class V composite resin restorations with three adhesives. Methods. Sixty freshly extracted human molars were selected and class V cavities (3×3×1.5 mm) were prepared on buccal and lingual surfaces. Gingival margins of the cavities were placed below the cementoenamel junction. The teeth were divided into six groups randomly. The adhesives were Excite, AdheSE and AdheSE One. In three groups, the gingival walls of the cavities were contaminated with ViscoStat and then rinsed. The cavities were restored with composite resin and light-cured. After storage in distilled water (37°C) for 24 hours and polishing, the samples were thermocycled and sealed with nail varnish. Then they were stored in 1% basic fuchsin for 24 hours, rinsed and mounted in self-cured acryl resin, followed by sectioning buccolingually. Dye penetration was observed under a stereomicroscope and scored. Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests. P<0.05 was set as the level of significance. Results. Only in the Excite group, contamination did not have adverse effects on dentin microleakage (P > 0.05). In the contaminated groups, Excite had significantly less microleakage than the others (P = 0.003). AdheSE and AdheSE One did not exhibit significant difference in microleakage (P > 0.05). Conclusion. ViscoStat hemostatic agent increased dentinal microleakage in AdheSE and AdheSE One adhesives with no effect on Excite. PMID:27092210

  17. Sealing of adhesive systems in ferric sulfate-contaminated dentinal margins in class V composite resin restorations

    PubMed Central

    Shadman, Niloofar; Farzin Ebrahimi, Shahram; Mollaie, Najmeh

    2016-01-01

    Background. Hemostatic agents are applied to prepare an isolated bleeding-free condition during dental treatments and can influence adhesive restorations. This study evaluated the effect of a hemostatic agent (ViscoStat) on microleakage of contaminated dentinal margin of class V composite resin restorations with three adhesives. Methods. Sixty freshly extracted human molars were selected and class V cavities (3×3×1.5 mm) were prepared on buccal and lingual surfaces. Gingival margins of the cavities were placed below the cementoenamel junction. The teeth were divided into six groups randomly. The adhesives were Excite, AdheSE and AdheSE One. In three groups, the gingival walls of the cavities were contaminated with ViscoStat and then rinsed. The cavities were restored with composite resin and light-cured. After storage in distilled water (37°C) for 24 hours and polishing, the samples were thermocycled and sealed with nail varnish. Then they were stored in 1% basic fuchsin for 24 hours, rinsed and mounted in self-cured acryl resin, followed by sectioning buccolingually. Dye penetration was observed under a stereomicroscope and scored. Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests. P<0.05 was set as the level of significance. Results. Only in the Excite group, contamination did not have adverse effects on dentin microleakage (P > 0.05). In the contaminated groups, Excite had significantly less microleakage than the others (P = 0.003). AdheSE and AdheSE One did not exhibit significant difference in microleakage (P > 0.05). Conclusion. ViscoStat hemostatic agent increased dentinal microleakage in AdheSE and AdheSE One adhesives with no effect on Excite. PMID:27092210

  18. Bonding performance and interfacial characteristics of short fiber-reinforced resin composite in comparison with other composite restoratives.

    PubMed

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2016-06-01

    The purpose of this study was to investigate the shear bond strength (SBS) and surface free-energy (SFE) of short fiber-reinforced resin composite (SFRC), using different adhesive systems, in comparison with other composite restoratives. The resin composites used were everX Posterior (EP), Clearfil AP-X (CA), and Filtek Supreme Ultra Universal Restorative (FS). The adhesive systems used were Scotchbond Multi-Purpose (SM), Clearfil SE Bond (CS), and G-Premio Bond (GB). Resin composite was bonded to dentin, and SBS was determined after 24 h of storage in distilled water and after 10,000 thermal cycles (TCs). The SFEs of the resin composites and the adhesives were determined by measuring the contact angles of three test liquids. The SFE values and SFE characteristics were not influenced by the type of resin composite, but were influenced by the type of adhesive system. The results of this study suggest that the bonding performance and interfacial characteristics of SFRC are the same as for other composite restoratives, but that these parameters are affected by the type of adhesive system. The bonding performance of SFRC was enhanced by thermal cycling in a manner similar to that for other composite restoratives. PMID:26954878

  19. X-ray diffraction analysis of residual stress in zirconia dental composites

    NASA Astrophysics Data System (ADS)

    Allahkarami, Masoud

    Dental restoration ceramic is a complex system to be characterized. Beside its essential biocompatibility, and pleasant appearance, it requires being mechanically strong in a catastrophic loading environment. Any design is restricted with geometry boundary and material property limits. Inspired by natural teeth, a multilayer ceramic is a smart way of achieving an enhanced restoration. Bi-layers of zirconia core covered by porcelain are known as one of the best multilayer restorations. Residual stresses may be introduced into a bi-layer dental ceramic restoration during its entire manufacturing process due to thermal expansion and elastic property mismatch. It is impossible to achieve a free of residual stresses bi-layer zirconia-porcelain restoration. The idea is to take the advantage of residual stress in design in such a way to prevent the crack initiation and progression. The hypothesis is a compressive residual stress at external contact surface would be enabling the restoration to endure a greater tensile stress. Optimizing the layers thickness, manufacturing process, and validating 3D simulations require development of new techniques of thickness, residual stresses and phase transformation measurement. In the present work, a combined mirco-tomography and finite element based method were adapted for thickness measurement. Two new 2D X-ray diffraction based techniques were adapted for phase transformation area mapping and combined phase transformation and residual stress measurement. Concerning the complex geometry of crown, an efficient method for X-ray diffraction data collection mapping on a given curved surface was developed. Finally a novel method for 3D dimensional x-ray diffraction data collection and visualization were introduced.

  20. Fracture Toughness of Veneering Ceramics for Fused to Metal (PFM) and Zirconia Dental Restorative Materials

    PubMed Central

    Quinn, Janet B.; Quinn, George D.; Sundar, Veeraraghaven

    2010-01-01

    Veneering ceramics designed to be used with modern zirconia framework restorations have been reported to fracture occasionally in vivo. The fracture toughness of such veneering ceramics was measured and compared to that of conventional feldspathic porcelain veneering ceramics for metal framework restorations. The fracture toughness of the leucite free veneer was measured to be 0.73 MPa m ± 0.02 MPa m, which is less than that for the porcelain fused to metal (PFM) veneering ceramic: 1.10 MPa ± 0.2 MPa. (Uncertainties are one standard deviation unless otherwise noted.) The surface crack in flexure (SCF) method was suitable for both materials, but precrack identification was difficult for the leucite containing feldspathic porcelain PFM veneer. PMID:21833158

  1. Clinical challenges and the relevance of materials testing for posterior composite restorations.

    PubMed

    Sarrett, David C

    2005-01-01

    Posterior composite restorations have been in use for approximately 30 years. The early experiences with this treatment indicated there were more clinical challenges and higher failure rates than amalgam restorations. Since the early days of posterior composites, many improvements in materials, techniques, and instruments for placing these restorations have occurred. This paper reviews what is known regarding current clinical challenges with posterior composite restorations and reviews the primary method for collecting clinical performance data. This review categorizes the challenges as those related to the restorative materials, those related to the dentist, and those related to the patient. The clinical relevance of laboratory tests is discussed from the perspective of solving the remaining clinical challenges of current materials and of screening new materials. The clinical problems related to early composite materials are no longer serious clinical challenges. Clinical data indicate that secondary caries and restoration fracture are the most common clinical problems and merit further investigation. The effect of the dentist and patient on performance of posterior composite restorations is unclear and more clinical data from hypothesis-driven clinical trials are needed to understand these factors. Improvements in handling properties to ensure void-free placement and complete cure should be investigated to improve clinical outcomes. There is a general lack of data that correlates clinical performance with laboratory materials testing. A proposed list of materials tests that may predict performance in a variety of clinical factors is presented. Polymerization shrinkage and the problems that have been attributed to this property of composite are reviewed. There is a lack of evidence that indicates polymerization shrinkage is the primary cause of secondary caries. It is recommended that composite materials be developed with antibacterial properties as a way of

  2. Restoration of divergent implants with a 2-piece screw-retained fixed, complete dental implant prostheses.

    PubMed

    Pelekanos, Stavros; Pozidi, Georgia; Kourtis, Stefanos

    2016-04-01

    Restoring a severely resorbed maxilla is challenging because of poor bone quality and the resorptive pattern that follows tooth loss. When bone augmentation is not possible, implants are placed in suboptimal positions, making the prosthetic rehabilitation more complex. This report presents the steps used to rehabilitate a severely resorbed maxilla with divergent implants, using an implant-supported 2-piece screw-retained prosthesis. PMID:26597464

  3. Endodontic complications in teeth with vital pulps restored with composite resins: a systematic review.

    PubMed

    Dawson, V S; Amjad, S; Fransson, H

    2015-07-01

    Composite resin is used extensively for restoration of teeth with vital pulps. Although cell culture studies have disclosed harmful effects on pulpal cells, any untoward clinical effects, manifest as adverse pulpal responses, have yet to be determined. This study comprises a systematic review, designed to address the question of whether the risk of endodontic complications is greater with composite resin restorations than with other restorative materials, such as amalgam. The study methodology involved (i) formulation of the research question, (ii) construction and conduct of an extensive literature search with (iii) interpretation and assessment of the retrieved literature. A search of the medical database PubMed was complemented with a search of the Controlled Trials Register (CENTRAL). The initial search yielded 1043 publications, the abstracts of which were read independently by the authors. After additional searches, 10 studies were included in the review. In all the included studies, the level of evidence was assessed as low. No conclusions could therefore be drawn. The included studies reported few, if any, endodontic complications. Little or no differences emerged between teeth restored with composite resins and those restored with amalgam. To determine whether composite resin restorations of teeth with vital pulps are associated with an increased risk for development of endodontic complications such as apical periodontitis, further evidence is needed, from well-constructed studies with a large number of participants. PMID:25100025

  4. Leached components from dental composites in oral simulating fluids and the resultant composite strengths.

    PubMed

    Lee, S Y; Huang, H M; Lin, C Y; Shih, Y H

    1998-08-01

    The aim of this study was to analyse the leached moieties of dental composites after storage in ethanol and organic acids of plaque and further evaluate the resultant effect on the diametral tensile strength (DTS) of the composites. Three commercial composites were used: Bis-GMA-based Z100, Bis-GMA/UDMA-based Heliomolar, and Bis-MPEPP-based Marathon One. The solutions used were: 99.9% acetic acid, 99% propionic acid and 75% ethanol. Specimens (4 mm diam. x 2 mm thick) were stored at 37 degrees C in 3 mL of solution for up to 30 days. Gas chromatography/mass spectrometry was used to characterize the leached moieties and DTS of the specimens after immersion was evaluated. Data were analysed using ANOVA and Tukey LSD test. The eluted substances were not all the same in different solutions and composites but mostly increased with immersion time, and included diluents (TEGDMA and decamethacrylate) and some additives, such as an ultra-violet stabilizer (TINUVINP), plasticizers (dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate), initiator (triphenyl stibine), coupling agent (gamma-methacryloxypropyl trimethoxysilane), and phenyl benzoate. The chief polymerizing monomers were not found. More kinds of components were found in the acetic acid and ethanol groups studied. The fewest kinds and quantities of leached moieties were found for Bis-GMA specimens and then Bis-GMA/UDMA ones, most of which are diluent agents. Bis-MPEPP specimens leached the most substances, which were composed mostly of a short phenyl group chain structure. The BisGMA composite showed the highest DTS (54.8 +/- 5.7 MPa), which was not greatly affected by the length of storage. Bis-GMA/UDMA (36.2 +/- 6.8 MPa) and Bis-MPEPP (26.1 +/- 4.5 MPa) composites were significantly reduced (P < 0.05) after 30 days storage in the ethanol (35-50%), in the propionic acid (25-30%), and in the acetic acid (40-60%). Irreversible processes such as the leaching of components occur in fluids simulating an oral

  5. Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

    NASA Astrophysics Data System (ADS)

    Astrath, F. B. G.; Astrath, N. G. C.; Baesso, M. L.; Bento, A. C.; Moraes, J. C. S.; Santos, A. D.

    2012-01-01

    Thermal diffusivity and conductivity of dental cements have been studied using open photoacoustic cell (OPC). The samples consisted of fast hardening cement named CER, developed to be a root-end filling material. Thermal characterization was performed in samples with different gel/powder ratio and particle sizes and the results were compared to the ones from commercial cements. Complementary measurements of specific heat and mass density were also performed. The results showed that the thermal diffusivity of CER tends to increase smoothly with gel volume and rapidly against particle size. This behavior was linked to the pores size and their distribution in the samples. The OPC method was shown to be a valuable way in deriving thermal properties of porous material.

  6. Long-term clinical evaluation of fracture and pulp injury following glass-ionomer cement or composite resin applied as a base filling in teeth restored with amalgam.

    PubMed

    De C Luz, M A; Ciaramicoli-Rodrigues, M T; Garone Netto, N; De Lima, A C

    2001-07-01

    The aim of this research was to analyse the long-term clinical behaviour of two dental materials applied as filling under silver amalgam restorations: glass-ionomer cement (GIC) and composite resin with adhesive system (CR). In this study, 117 posterior teeth (29 premolars and 88 molars) were selected with carious lesions which resulted in great loss of dentin and cusps with unsupported enamel. After caries removal, cavities were prepared and totally filled with GIC or with CR. In a following visit, new cavities were prepared, leaving the employed filling material as a base and support for the enamel, which were then restored with silver amalgam. Restorations were evaluated periodically after 6 months and up to 5 years. Both fracture and pulpal involvement rates were low. Although differences could be observed in the behaviour of the materials, statistical survival estimation showed that the performances of GIC and CR as filling material were similar. There was a significant association both between kind of tooth (molar or premolar) and long-term survival of the restorations; and between degree of unsupported enamel and the same long-term survival. Our results confirmed that the technique in which GIC or CR are used as filling under silver amalgam restorations is clinically acceptable. PMID:11422695

  7. Dental OCT

    NASA Astrophysics Data System (ADS)

    Colston, Bill W.; Sathyam, Ujwal S.; Dasilva, Luiz B.; Everett, Matthew J.; Stroeve, Pieter; Otis, L. L.

    1998-09-01

    We present here the first in vivo optical coherence tomography (OCT) images of human dental tissue. A novel dental optical coherence tomography system has been developed. This system incorporates the interferometer sample arm and transverse scanning optics into a handpiece that can be used intraorally to image human dental tissues. The average imaging depth of this system varied from 3 mm in hard tissues to 1.5 mm in soft tissues. We discuss the application of this imaging system for dentistry and illustrate the potential of our dental OCT system for diagnosis of periodontal disease, detection of caries, and evaluation of dental restorations.

  8. Microleakage of Dual-Cured Adhesive Systems in Class V Composite Resin Restorations

    PubMed Central

    Kasraie, S.; Azarsina, M.; Khamverdi, Z.; Shokraneh, F.

    2012-01-01

    Objective: Microleakage is a major factor affecting longevity of composite restorations. This study evaluated the effect of polymerization mode of bonding agent on microleakage of composite restorations. Materials and Methods: Forty-eight Class V cavities were prepared on buccal and lingual surfaces of 24 extracted human premolars. Occlusal and gingival margins were placed in the enamel and dentin, respectively. Teeth were divided into four groups as follows: Group I: Optibond Solo Plus (light-cured); Group II: Optibond Solo Plus (dual-cured); Group III: Prime & Bond NT (light-cured), Group IV: Prime & Bond NT (dual-cured). Teeth were restored using Z250 composite in three increments. After polishing the restorations, samples were thermocycled for 1000 cycles and stored in distilled water for 3 months. Then they were placed in 2% fuchsine solution for 48 hours. The samples were sectioned longitudinally and evaluated for microleakage under a stereomicroscope at ×40 magnification. Dye penetration was scored on a 0–3 ordinal scale. Data were analyzed using Kruskal-Wallis, Bonferroni and Wilcoxon signed ranks test. Results: Microleakage was significantly lower in enamel margins compared to dentin margins (P<0.05); multiple comparisons by Bonferroni tests revealed that the only factor with significant effect on leakage of the restoration is location of the restoration margin. Mode of adhesive polymerization had no significant influence on microleakage (P>0.05). Prime & Bond NT had less microleakage compared to Optibond SoloPlus, but the difference was not significant (P>0.05). Conclusion: There was no difference in the amount of microleakage in Class V composite restorations using light-cured and dual-cured bonding systems. Dentinal margins of restorations exhibited more microleakage than enamel margins. PMID:23066474

  9. Biomechanical behavior of restored and unrestored mandible with shortened dental arch under vertical loading condition.

    PubMed

    Tanasić, Ivan; Tihaček-Šojić, Ljiljana; Milić-Lemić, Aleksandra

    2012-01-01

    The aim of this in vitro study was to investigate the strain distribution of the compressed mandible bone under the applied restoration- removable partial denture and to compare with the same but unrestored mandible under vertical (occlusal) load and to find out whether removable partial denture-restored or unrestored mandible causes greater strain effect on supporting tissue. Four mandible models were tested during loading for the purpose of strain measuring. Digital image correlation system (GOM - German Optical Measuring, Braunschweig, Germany), used for measuring strain consists of two digital cameras and software ARAMIS (6.2.0, Braunschweig, Germany). Remaining teeth suffer from greater strain in the mandible model without removable partial denture (7.5-10%). On the contrary, mandible with removable partial denture shows the maximum strain below the denture saddle (3.5%). However, it can be noticed that the marginal bone of the second lower praemolar in both experimental models is deformed whether the mandible model has (2.8%) or has not (10%) replacement. Within the limitations of this study the higher strain is observed in mandible model without replacement and the strain is limited locally, in the bone region that surrounds remaining teeth and mental foramen. PMID:23394230

  10. The assessment of surface roughness and microleakage of eroded tooth-colored dental restorative materials

    PubMed Central

    Hussein, Thulfiqar Ali; Bakar, Wan Zaripah Wan; Ghani, Zuryati Ab; Mohamad, Dasmawati

    2014-01-01

    Objectives: To investigate the effect of acidic solution on surface roughness and microleakage of tooth-colored restorative materials. Materials and Methods: A 160 box-shaped cavities were prepared on the buccal surfaces of 160 human molars, and assigned to four groups: Group A restored with Ketac™ Molar Easymix, Group B with Fuji II™ LC, Group C with Ketac™ N100, and Group D with Filtek™ Z250, and subdivided into study and control groups (n = 20). Study groups were immersed in lemon juice (pH = 2.79) for 24 h, whilst controlgroups in deionized distilled water. All samples were immersed in 2% methylene blue dye, sectioned into two equal halves for surface roughness, and microleakage tests. Data were analyzed using Mann–Whitney and Kruskal–Wallis tests at P < 0.05. Results: There was a significant difference in surface roughness of Ketac™ Molar, Fuji II™ LC, and Ketac™ N100. No significant difference was found in microleakage of Ketac™ Molar and Fuji II™ LC; however, there were significant differences in the gingival margin of Ketac™ N100, and the occlusal margin of Filtek™ Z250. Conclusions: All glass ionomer cements were eroded after exposure to the acidic drink. Filtek™ Z250 and Ketac™ Molar Easymix showed more microleakage. All materials showed more microleakage at the gingival margins. PMID:25506139

  11. Microleakage of Posterior Composite Restorations with Fiber Inserts Using two Adhesives after ging

    PubMed Central

    Sharafeddin, F; Yousefi, H; Modiri, Sh; Tondari, A; Safaee Jahromi, SR

    2013-01-01

    Statement of Problem: Microleakage is one of the most frequent problems associated with resin composites, especially at the gingival margin of posterior restorations. Insertion of fibers in composite restorations can reduce the total amount of composite and help to decrease the shrinkage. Purpose: The aim of this study was to evaluate the effect of polyethylene fiber inserts on gingival microleakage of class II composite restorations using two different adhesive systems. Materials and Method: In this experimental study, class II cavities were prepared on 60 premolars. The gingival floor was located 1.0 mm below the CEJ. Dimension of each cavity were 3 mm buccolingually and 1.5 mm in axial depth. The specimens were divided into 4 groups according to the adhesive type and fiber insert (n=4). Single bond and Clearfill SE bond and Filtek p60 were used to restore the cavities. In groups without fiber inserts composite was adapted onto cavities using layering technique. For cavities with fiber inserts, 3 mm piece of fiber insert was placed onto the composite increment and cured. The specimens were stored in distilled water at 37oC for 6 months. All specimens were subjected to 3000 thermo-cycling. The tooth surfaces except for 1 mm around the restoration margins covered with two layers of nail varnish .The teeth were immersed in 2% Basic Fuchsin for 24 hours, then rinsed and sectioned mesiodistally. The microleakage was determined under a stereomicroscope (40X). Data were statistically analyzed by Kruskal-wallis and Mann-Whitney U tests (p< 0.05). Results: The Kruskal-Wallis test revealed no significant differences in mean microleakage scores among all groups (p= 0.281). Conclusion: Use of polyethylene fiber inserts and etch-and-rinse and self-etch adhesives had no effect on microleakage in class II resin composite restorations with gingival margins below the CEJ after 6- month water storage. PMID:24724129

  12. Short Fiber Reinforced Composite: a New Alternative for Direct Onlay Restorations

    PubMed Central

    Garoushi, Sufyan; Mangoush, Enas; Vallittu, Mangoush; Lassila, Lippo

    2013-01-01

    Objectives: To determine the static load-bearing capacity of direct composite onlay restorations made of novel filling composite resin system which combines short fiber-reinforced composite resin (FC) and conventional particulate filler composite resin (PFC). Methods: Three groups of onlay restorations were fabricated (n = 8/group); Group A: made from conventional particulate filler composite resin (Z250, 3M-ESPE, USA, control), Group B: made from short fiber-reinforced composite resin (EverX posterior, StickTeck Ltd, member of GC group, Turku, Finland) as substructure with 1 mm surface layer of PFC, Group C: made from FC composite resin. The specimens were incrementally polymerized with a hand-light curing unit for 80 s before they were statically loaded with two different sizes (3 & 6 mm) of steel ball until fracture. Failure modes were visually examined. Data were analyzed using ANOVA (p = 0.05). Results: ANOVA revealed that onlay restorations made from FC composite resin had statistically significantly higher load-bearing capacity (1733 N) ( p < 0.05) than the control PFC composite resin (1081 N). Onlays made of FC composite resin with a surface layer of PFC gave force values of 1405 N which was statistically higher than control group ( p < 0.05). No statistically significant difference was found in the load-bearing capacity between groups loaded by different ball sizes Significance: Onlay restorations combining base of short fiber reinforced composite resin as substructure and surface layer of conventional composite resin displayed promising performance in high load bearing areas. PMID:24511331

  13. Composition of enamel pellicle from dental erosion patients.

    PubMed

    Carpenter, G; Cotroneo, E; Moazzez, R; Rojas-Serrano, M; Donaldson, N; Austin, R; Zaidel, L; Bartlett, D; Proctor, G

    2014-01-01

    Oral health is dependent upon a thin mobile film of saliva on soft and hard tissues. Salivary proteins adhere to teeth to form the acquired enamel pellicle which is believed to protect teeth from acid erosion. This study investigated whether patients suffering diet-induced dental erosion had altered enamel pellicles. Thirty patients suffering erosion were compared to healthy age-matched controls. Subjects wore a maxillary splint holding hydroxyapatite and human enamel blocks for 1 h. The acquired enamel pellicle was removed from the blocks and compared to the natural incisor pellicle. Basic Erosive Wear Examination scores confirmed that dental erosion was present in erosion patients and absent from healthy age-matched controls. Erosion patients had half the amount of proteins (BCA assay) within the acquired pellicle forming on splint blocks compared to normal controls (p < 0.05). In particular, statherin, a calcium-binding protein, was 35% less abundant (p < 0.05). Calcium concentration within the acquired pellicle was also reduced by 50% in erosion patients (p < 0.001). In contrast, the natural pellicle on the incisor had similar amounts of total protein in erosion patients and healthy controls. In summary, the formation of new acquired pellicles on surfaces was reduced in erosion patients, which may explain their greater susceptibility to acid erosion of teeth. PMID:24603346

  14. Composite titanium dental implant fabricated by electro-discharge compaction.

    PubMed

    Qiu, J; Dominici, J T; Lifland, M I; Okazaki, K

    1997-01-01

    An electro-discharge compaction (EDC) fabrication window was established for producing commercially pure porous titanium dental implants of 4 mm diameter and 7 mm length with a solid titanium cap. The optimum input energy was in the range of 0.58-0.87 kJ g-1 for a powder column of 0.500 g. Input energy greater than 0.58 kJ g-1 resulted in an implant torque strength exceeding 30 N-cm (the retaining screw tightening torque), while input energy greater than 0.72 kJ g-1 exceeded 46.7 N-cm torque strength (at this level the retaining screw failed prior to the implant). The integrity of the internally threaded hole and hexagonal head of the cap were maintained throughout the EDC process. The EDC process did not after the strength and/or microstructure of the components, and the bead-cap interface was stronger than the bead-bead interface. EDC implants produced within the aforementioned window have sufficient compressive strengths and other physical properties to meet the requirement for titanium dental implants. PMID:9022963

  15. Dental applications of nanostructured bioactive glass and its composites

    PubMed Central

    Polini, Alessandro; Bai, Hao; Tomsia, Antoni P.

    2013-01-01

    To improve treatments for bone or dental trauma, and for diseases such as osteoporosis, cancer, and infections, scientists who perform basic research are collaborating with clinicians to design and test new biomaterials for the regeneration of lost or injured tissue. Developed some 40 years ago, bioactive glass (BG) has recently become one of the most promising biomaterials, a consequence of discoveries that its unusual properties elicit specific biological responses inside the body. Among these important properties are the capability of BG to form strong interfaces with both hard and soft tissues, and its release of ions upon dissolution. Recent developments in nanotechnology have introduced opportunities for materials sciences to advance dental and bone therapies. For example, the applications for BG expand as it becomes possible to finely control structures and physicochemical properties of materials at the molecular level. Here we review how the properties of these materials have been enhanced by the advent of nanotechnology; and how these developments are producing promising results in hard-tissue regeneration and development of innovative BG-based drug-delivery systems. PMID:23606653

  16. Evaluation of cuspal deflection in premolar teeth restored with low shrinkable resin composite (in vitro study)

    PubMed Central

    Labib, Labib Mohamed; Nabih, Sameh Mahmoud; Baroudi, Kusai

    2015-01-01

    Objectives: This study evaluated cuspal deflection in premolar teeth restored with low shrinkable resin composite. Materials and Methods: A total of 40 human premolars were used for cuspal deflection evaluation in this study. Each group was divided into four equal groups according to the type of resin composite and the adhesive used as follows: group A: Using low shrinkable resin composite (silorane) with its adhesive system; group B: Using low shrinkable composite (silorane) with G-bond; group C: Using Filtek Z350 composite with G-bond; and group D: Using Filtek Z350 composite with AdheSE. Cusp deflection was detected using Universal measuring microscope and laser horizontal metroscope. Results: This study was done to investigate the effect of polymerization shrinkage stresses of two resin composite materials (Filtek Z350 and Filtek P90) on cuspal deflection of mesio-occluso-distal restoration. For this study, the extracted non-carious maxillary second premolars were selected. Forty teeth that showed no more than 5% variation in their dimensions were used. A significant increase in cuspal deflection of cavities restored with the methacrylate-based (Filtek Z350) compared with the silorane (P90) resin-based composites was obtained. Conclusion: The change in the organic matrix or materials formulation of the resin composite using silorane has a positive effect on controlling the cusp deflection. PMID:26759800

  17. Chipping fracture resistance of dental CAD/CAM restorative materials: Part 2. Phenomenological model and the effect of indenter type

    PubMed Central

    Quinn, G.D.; Giuseppetti, A.A.; Hoffman, K.H.

    2014-01-01

    The edge chipping resistances of six CAD/CAM dental restoration materials are analyzed and correlated to other mechanical properties. A new quadratic relationship that is based on a phenomenological model is presented. Objective The purpose of this study was to further analyze the edge chipping resistance of the brittle materials evaluated in Part 1. One objective was to determine why some force-distance trends were linear and others were nonlinear. A second objective was to account for differences in chipping resistance with indenter type. Methods Edge chipping experiments were conducted with different indenters, including some custom-made sharp conical indenters. A new force – distance quadratic expression was correlated to the data and compared to the linear and power law trends. Results The new quadratic function was an excellent fit in every instance. It can account for why some materials can be fit by a linear trend, while others can be fit by the power law trend. The effects of indenter type are accounted for variations in crack initiation and by the wedging stresses once an indentation hole is created. Significance The new quadratic force – edge distance function can be used with edge chipping data for all brittle materials, not just those evaluated in this study. The data trends vary from linear to nonlinear depending upon the material’s hardness, fracture toughness, and elastic modulus. PMID:24685179

  18. Highly-translucent, strong and aging-resistant 3Y-TZP ceramics for dental restoration by grain boundary segregation.

    PubMed

    Zhang, Fei; Vanmeensel, Kim; Batuk, Maria; Hadermann, Joke; Inokoshi, Masanao; Van Meerbeek, Bart; Naert, Ignace; Vleugels, Jef

    2015-04-01

    Latest trends in dental restorative ceramics involve the development of full-contour 3Y-TZP ceramics which can avoid chipping of veneering porcelains. Among the challenges are the low translucency and the hydrothermal stability of 3Y-TZP ceramics. In this work, different trivalent oxides (Al2O3, Sc2O3, Nd2O3 and La2O3) were selected to dope 3Y-TZP ceramics. Results show that dopant segregation was a key factor to design hydrothermally stable and high-translucent 3Y-TZP ceramics and the cation dopant radius could be used as a controlling parameter. A large trivalent dopant, oversized as compared to Zr(4+), exhibiting strong segregation at the ZrO2 grain boundary was preferred. The introduction of 0.2 mol% La2O3 in conventional 0.1-0.25 wt.% Al2O3-doped 3Y-TZP resulted in an excellent combination of high translucency and superior hydrothermal stability, while retaining excellent mechanical properties. PMID:25662163

  19. Study of the surface wear resistance and biological properties of the Ti-Zr-Nb-Sn alloy for dental restoration.

    PubMed

    Hu, Xin; Wei, Qiang; Li, Chang-Yi; Deng, Jia-Yin; Liu, Shuang; Zhang, Lian-Yun

    2010-10-01

    A new titanium alloy (Ti-12.5Zr-3Nb-2.5Sn) was developed to meet the needs of clinical requirements for medical titanium alloys and improve the properties of existing titanium alloys. The as-prepared alloy was solution treated at 500 °C for 3 h in vacuum followed by water quenching. Tensile, wear and hardness tests were carried out to examine the mechanical properties of the Ti-Zr-Nb-Sn alloy. Oral mucous membrane irritation test was performed to evaluate the surface biological properties of the Ti-Zr-Nb-Sn alloy. The results suggested that the surface hardness and wear-resistant properties of the Ti-12.5Zr-3Nb-2.5Sn alloy were superior to commercially pure Ti. The oral mucous irritation test showed that all samples had no mucous membrane irritation. It indicates that Ti-12.5Zr-3Nb-2.5Sn has large potential to be used as dental restoration material. PMID:20876964

  20. Influence of dental resin material composition on cross-polarization-optical coherence tomography imaging

    PubMed Central

    Lammeier, Carmen; Li, YuPing; Lunos, Scott; Fok, Alex; Rudney, Joel

    2012-01-01

    Abstract. The purpose of this study was to investigate cross-polarization-optical coherence tomography (CP-OCT) signal attenuation through different resin material compositions. Four distinct composite systems were used: Filtek supreme ultra (FSU) (3M ESPE), IPS empress direct (EMD) (Ivoclar Vivadent), estelite sigma quick (SQK) (Tokuyama Dental), and Z100 (3M ESPE). Cross-sectional images of different composite-demineralized phantoms (n=108) were collected using a 1310-nm intraoral cross-polarization swept source OCT (CP-OCT) imaging system. %T quantified the CP-OCT signal attenuation. Scanning electron microscopy, transmission electron microscopy, and energy-dispersive x-ray spectrometer chemical analysis was utilized to determine how different matrix/filler compositions affected attenuation of the near infrared (NIR) signal. CP-OCT imaging of dental resin composites showed enormous variation in signal attenuation. For each of our composite systems, there was not a consistent attenuation difference in the NIR signal for A to D shades. The four composites had similar measured backscattering values but attenuated the overall signal to different degrees. When comparing the A2 shades between the four different composite systems, the order of highest to lowest of %T was EMD>Z100, FSU>SQK (ANOVA, Tukey, p<0.0001). As a result, we demonstrate the importance of understanding how the constituents of composite materials affect CP-OCT signal attenuation. PMID:23224001

  1. Bis-GMA/TEGDMA Dental Composites Reinforced with Electrospun Nylon 6 Nanocomposite Nanofibers Containing Highly Aligned Fibrillar Silicate Single Crystals

    PubMed Central

    Tian, Ming; Gao, Yi; Liu, Yi; Liao, Yiliang; Xu, Riwei; Hedin, Nyle E.; Fong, Hao

    2007-01-01

    The objective of this research was to study the reinforcement of electrospun nylon 6/fibrillar silicate nanocomposite nanofibers on Bis-GMA/TEGDMA dental composites. The hypothesis was that the uniform distribution of nano-scaled and highly aligned fibrillar silicate single crystals into electrospun nylon 6 nanofibers would improve the mechanical properties of the resulting nanocomposite nanofibers, and would lead to the effective reinforcement of dental composites. The nylon 6/fibrillar silicate nanocomposite nanofibers were crystalline, structurally oriented and had an average diameter of approximately 250 nm. To relatively well distribute nanofibers in dental composites, the nanofiber containing composite powders with a particle structure similar to that in interpenetration networks were prepared first, and then used to make the dental composites. The results indicated that small mass fractions (1 % and 2 %) of nanofiber impregnation improved the mechanical properties substantially, while larger mass factions (4 % and 8 %) of nanofiber impregnation resulted in less desired mechanical properties. PMID:17940586

  2. Enhancement of mechanical properties of experimental composite by Fuller's earth nanofibers for cervical restoration.

    PubMed

    Houshyar, Aydin; Khavandi, Ali Reza; Javadpour, Jafar; Samani, Saeed; Naimi-Jamal, Mohammad Reza; Atai, Mohammad

    2013-08-01

    In this research, we studied improvement of mechanical properties of dimethacrylate-silica based dental composites by addition of Fuller's Earth (FE) clay. Three composites were made as base compounds consisting of 68, 58, and 48 wt % resin and 31, 41, and 51 wt % silica, respectively. Afterward, the composites were modified by adding FE. Mechanical properties including flexural strength, flexural modulus, work-of-fracture, fracture toughness, and microhardness were measured. Clay particles and fracture surface of composites consisting of 51 wt % silica (with and without FE) were examined by SEM. Measured results showed that flexural strength, work-of-fracture, flexural modulus, and microhardness of all composites increased by including FE nanofibers. Fracture toughness except for composite including 51 wt % silica had similar variations. It seems that locating FE nanofibers in weak resin region among silica particles leads to strengthening mechanisms, such as bridging and crack deflection, which cause improvement in mechanical properties. PMID:23401393

  3. Effect of 38% carbamide peroxide on the microleakage of silorane-based versus methacrylate-based composite restorations

    PubMed Central

    Ghavam, Maryam; Mahinfar, Nazanin; Pourhashemi, Seyed Jalal

    2014-01-01

    Objectives This study aimed to assess the effect of 38% carbamide peroxide on the microleakage of class V cavities restored with either a silorane-based composite or two methacrylate-based composites. Materials and Methods A total of 96 class V cavities were prepared on the buccal surface of extracted human teeth with both enamel and dentin margins and were randomly assigned into three groups of Filtek P90 (3M-ESPE) + P90 system adhesive (3M-ESPE)(group A), Filtek Z250 (3M-ESPE) + Adper Prompt L-Pop (3M-ESPE)(group B) and Filtek Z350XT (3M-ESPE) + Adper Prompt L-Pop (group C). Half of the teeth were randomly underwent bleaching (38% carbamide peroxide, Day White, Discus Dental, applying for 15 min, twice a day for 14 day) while the remaining half (control) were not bleached. Dye penetration was measured following immersion in basic fuchsine. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at a level of 0.05. Results No significant differences were found between composites in the control groups in enamel (p = 0.171) or dentin (p = 0.094) margins. After bleaching, microleakage of Z250 (in enamel [p = 0.867] or dentin [p = 0.590] margins) and Z350 (in enamel [p = 0.445] or dentin [p = 0.591] margins) did not change significantly, but the microleakage of P90 significantly increased in both enamel (p = 0.042) and dentin (p = 0.002) margins. Conclusions No significant differences were noted between the bleached and control subgroups of two methacrylate-based composites in enamel or dentin margins. Microleakage of silorane-based composite significantly increased after bleaching. PMID:25110640

  4. Indirect composite restorations luted with two different procedures: A ten years follow up clinical trial

    PubMed Central

    Preti, Alessandro; Vano, Michele; Derchi, Giacomo; Mangani, Francesco; Cerutti, Antonio

    2015-01-01

    Objectives: The aim of this clinical trial was to evaluate posterior indirect composite resin restoration ten years after placement luted with two different procedures. Study Design: In 23 patients 22 inlays/onlays (Group A) were luted using a dual-cured resin composite cement and 26 inlays/onlays (Group B) were luted using a light cured resin composite for a total of 48 Class I and Class II indirect composite resin inlays and onlays. The restorations were evaluated at 2 time points: 1) one week after placement (baseline evaluation) and 2) ten years after placement using the modified USPHS criteria. The Mann-Whitney and the Wilcoxon tests were used to examine the difference between the results of the baseline and 10 years evaluation for each criteria. Results: Numerical but not statistically significant differences were noted on any of the recorded clinical parameters (p>0.05) between the inlay/onlays of Group A and Group B. 91% and 94 % of Group A and B respectively were rated as clinically acceptable in all the evaluated criteria ten years after clinical function. Conclusions: Within the limits of the study the results showed after ten years of function a comparable clinical performance of indirect composite resin inlays/onlays placed with a light cure or dual cure luting procedures. Key words:Light curing composite, dual curing composite, indirect composite restoration, inlays/onlays, clinical trial. PMID:25810842

  5. Fracture resistance of teeth restored with class II bonded composite resin.

    PubMed

    Eakle, W S

    1986-02-01

    The purpose of this study was to determine whether composite resin bonded to enamel or to both enamel and dentin can increase the fracture resistance of teeth with Class II cavity preparations. Extracted maxillary pre-molars with MOD slot preparations were restored with composite resin bonded to enamel (P-30 and Enamel Bond) or composite resin bonded to enamel and dentin (P-30 and Scotch-bond). Teeth in a control group were prepared but left unrestored. All teeth were loaded occlusally in a universal testing machine until they fractured. Means of forces required to fracture teeth in each of the three groups were statistically compared (one-way ANOVA and Bonferroni t test). Teeth restored with combined enamel- and dentin-bonded composite resins were significantly more resistant to fracture than were similarly prepared but unrestored teeth and also than teeth restored with enamel-bonded composite resin (p less than 0.05). A significant difference was not demonstrated between the enamel-bonded group and the unrestored group. Further testing is needed to determine the durability of the bonds between tooth and restoration in the clinical setting. PMID:3511111

  6. Considerations regarding the optical properties of the composite resin restorative materials.

    PubMed

    Manolea, H; Râcă, R; Coleş, Evantia; Preotu, Gabriela; Mărăşescu, P

    2011-07-01

    The purpose of this study has been to investigate the effects of certain substances frequently used in alimentation on the color stability of the composite resin restorative materials. The research hypothesis was that color stability of the composite resin is affected by the type of composite material used and by the polishing procedure. 14 samples of 5X15X2mm have been prepared from seven universal light curing restorative composite resins. The materials have manipulated and cured using LA 500 Blue Light lamp. A first color determination was done before the introduction of the samples in the dyeing agent with the help of an Easy Shade device. The samples have been splited into two lots each with seven samples. The samples from the first lot have been sectioned into three equal segments. The samples from the second lot have also been sectioned into three equal segments, and in addition to the previous group, their exterior surfaces were processed with a diamond burr. For each type of composite we have introduced a sample in one of the three chosen dyes: red alimentary colorant, coffee and red wine. The color of the samples has been determined again using the Vita Easy Shade device. From clinical point of view the results of this study shows that there are three important factors that matter when we talk about durable aesthetic results: the type of composite resin used for the restoration, the finishing and polishing procedures and the pacients' alimentation habits. The composite resins with a good representation of the anorganic structure are easier to be polished, therefore they have only slight color modifications. Using plastic matrixes for shaping the exterior surface of the restoration is the best solution for obtaining a very smooth surface. The most significant color modifications have been done by the red wine. Coffee and to a smaller extent the red alimentary colorant have modified the color of the restoration material in a smaller degree. PMID:24778835

  7. [Surface modification and microstructure of single-walled carbon nanotubes for dental composite resin].

    PubMed

    Xia, Yang; Zhang, Feimin; Xu, Li'na; Gu, Ning

    2006-12-01

    In order to improve its dispersion condition in dental composite resin and enhance its interaction with the matrix, single-walled carbon nanotubes(SWNTs) were refluxed and oxidized, then treated by APTE. Their outer surface were coated by nano-SiO2 particles using sol-gel process, then further treated by organosilanes ATES. IR and TEM were used to analyze modification results. TEM pictures showed nano-particles were on the surface of SWNTs; IR showed characteristic adsorbing bands of SiO2. Composite resin specimen with modified SWNTs was prepared and examined by TEM. SWNTs were detected in composite resin matrix among other inorganic fillers. PMID:17228726

  8. The incorporation of nanoparticles into conventional glass-ionomer dental restorative cements.

    PubMed

    Gjorgievska, Elizabeta; Van Tendeloo, Gustaaf; Nicholson, John W; Coleman, Nichola J; Slipper, Ian J; Booth, Samantha

    2015-04-01

    Conventional glass-ionomer cements (GICs) are popular restorative materials, but their use is limited by their relatively low mechanical strength. This paper reports an attempt to improve these materials by incorporation of 10 wt% of three different types of nanoparticles, aluminum oxide, zirconium oxide, and titanium dioxide, into two commercial GICs (ChemFil® Rock and EQUIA™ Fil). The results indicate that the nanoparticles readily dispersed into the cement matrix by hand mixing and reduced the porosity of set cements by filling the empty spaces between the glass particles. Both cements showed no significant difference in compressive strength with added alumina, and ChemFil® Rock also showed no significant difference with zirconia. By contrast, ChemFil® Rock showed significantly higher compressive strength with added titania, and EQUIA™ Fil showed significantly higher compressive strength with both zirconia and titania. Fewer air voids were observed in all nanoparticle-containing cements and this, in turn, reduced the development of cracks within the matrix of the cements. These changes in microstructure provide a likely reason for the observed increases in compressive strength, and overall the addition of nanoparticles appears to be a promising strategy for improving the physical properties of GICs. PMID:25691120

  9. Substance P incorporation in calcium phosphate cement for dental alveolar bone defect restoration.

    PubMed

    Wang, Tianjue; Wu, Di; Li, Yuan; Li, Wantao; Zhang, Shuyin; Hu, Kaijin; Zhou, Hongzhi

    2016-12-01

    A combination of osteoinductive neuropeptide substance P (SP) and osteoconductive bone cement of calcium phosphate (CPC) might provide an effective and lower-cost solution for complex alveolar bone defects restoration. The present study aims to investigate the key design considerations of SP delivery in CPC. In this study, CPC-based modular scaffolds were developed, where collagen type I was used as accessory organic ingredient to modulate the physical and biological characters. SP was directly mixed in the cement as free peptides, or was covalently immobilized with collagen component. The structural and mechanical properties of the scaffolds were assessed in vitro, and their osteogenic ability was observed in a rabbit model with alveolar bone defect. The results showed that SP could enhance the osteo-conductivity/inductivity of CPC. Collagen solution optimized biocompatibility of CPC, and meanwhile exhibited additive effects on the functions of SP. Nevertheless, immobilization of SP with collagen blocked their bioactivity in CPC. Collagen sponges created macro-porosity in CPC and achieved maximum bone ingrowth with the aid of SP. In conclusion, the present study primarily demonstrated that CPC scaffold can be functionalized by synthetic SP, and the biocompatibility and porosity of the scaffold are adaptable key factors determining their final osteogenic activities. PMID:27612746

  10. Ablation by-products of dental materials from the Er:YAG laser and the dental handpiece

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-05-01

    Recently there has been much interest in lasers and their potential use to replace the dental drill. The research has been directed towards vital dental tissues. It must be understood that any laser to be used in dentistry which will replace the dental drill must also ablate and remove existing dental materials. Some concern exists about the ablation products when the Er:YAG laser is used to ablate dental materials. It is incumbent on the professionals using these lasers to understand the materials being produced by these lasers and protect themselves and their patients from possible toxic products. It is the intent of this paper to evaluate the products produced by the ablation of both dental amalgam and composite dental restorative materials and compare them with those produced by the traditional dental handpiece (drill).

  11. Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography

    PubMed Central

    TÜRK, Ayşe Gözde; SABUNCU, Metin; ÜNAL, Sena; ÖNAL, Banu; ULUSOY, Mübin

    2016-01-01

    ABSTRACT Objective The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT) to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. Material and Methods Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany) after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs), allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply), and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (p<0.05), before and after cementation. Results Direct inlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442) and after (p=0.00001466) cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively). The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. Conclusions Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after cementation

  12. [Tooth color matching systems and communication with dental laboratory in indirect restorations: 2011 update].

    PubMed

    Ginzburg, M; Gilboa, I

    2012-01-01

    There has been many technological developments in the last decade. Today's shade-matching technologies have been developed in an effort to increase the success of color matching, communication, reproduction and verification in clinical dentistry and, ultimately, to increase the efficiency of esthetic restorative work within any practice. In general, the output of the color measurements can be classified and specified in several ways. The most common systems for describing color are Munsell's System and the international Commission on Illumination (CIE) L a b color system. Albert Munsell described color as a three-dimensional phenomenon. He described the three dimensions as hue, value (brightness), and chroma (saturation). Visual colour determination by comparison of teeth and shade guides is the most frequently applied method in dentistry. Vitapan Classical (Vita Zahnfabrik, Germany) and its derivations(evidence-based Vitapan 3D-Master shade guide and Linearguide) are the most commonly used shade guides. However, several factors can influence consistency of visual colour selection and specification: individual colour matching ability may vary, the colour perception of any individual may show temporal variation, the range of shades available is inadequate and does not cover the complete colour space of natural teeth, the shade guide tabs are not systematically distributed in their colour space, and changes in lighting conditions can cause alterations in perceived colour. instruments for clinical shade-matching encompass spectrophotometers, colorimeters and digital imaging systems. It can be concluded that different devices have different accuracy and precision. Colorimeters are significantly less reliable than spectrophotometers and digital cameras. Benefits and limitations exist, and the clinician must consider how the technology relates to expectations and needs. Combination of visual colour determination (Vitapan 3D-Master shade guide and Linearguide) with

  13. The effects of glass ionomer and flowable composite liners on the fracture resistance of open-sandwich class II restorations.

    PubMed

    Güray Efes, Begüm; Yaman, Batu Can; Gümüştaş, Burak; Tıryakı, Murat

    2013-01-01

    This in vitro study aimed to investigate the effects of glass-ionomer and flowable composite liners on the fracture resistance of Class II amalgam and composite restorations. Group 1 cavities were restored with amalgam and Group 4 cavities with nanofill composite after the application of a dentin-bonding agent. For the remaining groups, light-cured-glass-ionomer liner was used in a gingival floor proximal box (Groups 2, 5) or flowable composite was used as a liner (Groups 3, 6), the remainder of the cavity was restored with amalgam (Groups 2, 3) or composite (Groups 5, 6). The restorations were loaded in compression to failure. The data was analyzed using Tukey's multiple comparison test. The fracture resistance was significantly higher (p<0.05) in Group 3 than in all other groups, except Group 2 (p>0.05). Flowable composite, glass-ionomer liners increased the fracture resistance of open-sandwich Class II amalgam restorations. PMID:24240900

  14. Effect of Bleaching Agents on the Nanohardness of Tooth Enamel, Composite Resin, and the Tooth-Restoration Interface.

    PubMed

    Abe, A T; Youssef, M N; Turbino, M L

    2016-01-01

    This in vitro study aimed to evaluate the nanohardness of tooth enamel, composite resin, dental adhesive, and enamel hybrid layer exposed to 35% hydrogen peroxide-based bleaching agents and analyze the tooth-restoration interface using scanning electron microscopy (SEM). This study used 40 crowns of bovine incisors, which were embedded in epoxy resin. A 2 × 2 × 2-mm cavity was prepared in the medial third of the flattened buccal surface of each tooth and restored (two-step etch-and-rinse Adper Single Bond 2 + nanocomposite resin Filtek Z350 XT). The specimens were polished and divided into four groups (n=10), corresponding to each bleaching agent used (TB: Total Blanc Office, pH=7.22-6.33; HPB: Whiteness HP Blue, pH=8.89-8.85; HP: Whiteness HP, pH=6.65-6.04; PO: Pola Office, pH=3.56-3.8), applied in accordance with manufacturer protocols. The nanohardness of the substrates was measured before and immediately after the bleaching procedure and after 7-day storage in artificial saliva with an Ultra-Microhardness Tester (DUH-211S, Shimadzu). Loads used were 100 mN for tooth enamel and composite resin and 10 mN for adhesive and enamel hybrid layer. For SEM analysis, epoxy replicas were prepared through high-precision impressions of the specimens. For nanohardness, the statistical tests two-way analysis of variance and Tukey (p<0.05) revealed that the agent with the lowest pH value (PO) was the only one to decrease the nanohardness of enamel and the enamel hybrid layer immediately after its application; however, after 7-day storage in artificial saliva, the nanohardness levels of these substrates returned to their original values. SEM analysis revealed small gaps between tooth enamel and adhesive after the exposure to all bleaching agents; however, the most evident gap in the tooth-restoration interface was observed immediately after application of agent PO. No bleaching agent used changed the nanohardness of the composite resin and adhesive layer. PMID:26266649

  15. REE compositions in fossil vertebrate dental tissues indicate biomineral preservation

    NASA Astrophysics Data System (ADS)

    Žigaite, Ž.; Kear, B.; Pérez-Huerta, A.; Jeffries, T.; Blom, H.

    2012-04-01

    Rare earth element (REE) abundances have been measured in a number of Palaeozoic and Mesozoic dental tissues using Laser Ablation Inductively Coupled Plasma Mass-spectrometry (LA-ICP-MS). Fossil vertebrates analysed comprise scales and tesserae of Silurian and Devonian acanthodians, chondrichthyans, galeaspids, mongolepids, thelodonts, as well as teeth of Cretaceous lungfish and marine reptiles. The evaluation of fossil preservation level has been made by semi-quantitative spot geochemistry analyses on fine polished teeth and scale thin sections, using Energy Dispersive X-ray Spectroscopy (EDS). Fossil teeth and scales with significant structure and colour alteration have shown elevated heavy element concentrations, and the silicification of bioapatite has been common in their tissues. Stable oxygen isotope measurements (δ18O) of bulk biomineral have been conducted in parallel, and showed comparatively lower heavy oxygen values in the same fossil tissues with stronger visible alteration. Significant difference in REE concentrations has been observed between the dentine and enamel of Cretaceous plesiosaurs, suggesting the enamel to be more geochemically resistant to diagenetic overprint.

  16. Marginal and internal fit of nano-composite CAD/CAM restorations

    PubMed Central

    Park, So-Hyun; Shin, Yoo-Jin

    2016-01-01

    Objectives The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations. Materials and Methods A full veneer crown and an mesio-occluso-distal (MOD) inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU) and experimental nano-composite CAD/CAM blocks (EB) under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis. Results Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000). In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001). Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000). Conclusions The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations. PMID:26877989

  17. Analysis of composites for restorative dentistry by PIXE, XRF and ERDA

    NASA Astrophysics Data System (ADS)

    Preoteasa, E. A.; Ciortea, C.; Constantinescu, B.; Fluerasu, D.; Enescu, S.-E.; Pantelica, D.; Negoita, F.; Preoteasa, E.

    2002-04-01

    Composites used in dentistry bring into the organism elements that may induce adverse biological effects. We applied 3 MeV proton particle-induced X-ray emission (PIXE) and photon-excited X-ray fluorescence (XRF) in the qualitative analysis of 10 dental composites and we tested copper-beam elastic recoil detection analysis (ERDA) on one material. PIXE, and partly XRF, evidenced Si, K, Ca, Ti, V, Cr, Fe, Mn, Ni, Cu, Zn, Sr, Ag, Zr, Cd, In, Ba, Yb, Y, Ho, Hf and Pb, many of them at trace levels, while ERDA detected H, B, C, N, O, F, Na, Al and Si.

  18. Predictive algorithms for determination of reflectance data from quantity of pigments within experimental dental resin composites

    PubMed Central

    2015-01-01

    Background Being able to estimate (predict) the final spectrum of reflectance of a biomaterial, especially when the final color and appearance are fundamental for their clinical success (as is the case of dental resin composites), could be a very useful tool for the industrial development of these type of materials. The main objective of this study was the development of predictive models which enable the determination of the reflectance spectrum of experimental dental resin composites based on type and quantity of pigments used in their chemical formulation. Methods 49 types of experimental dental resin composites were formulated as a mixture of organic matrix, inorganic filler, photo activator and other components in minor quantities (accelerator, inhibitor, fluorescent agent and 4 types of pigments). Spectral reflectance of all samples were measured, before and after artificial chromatic aging, using a spectroradiometer. A Multiple Nonlinear Regression Model (MNLR) was used to predict the values of the Reflectance Factors values in the visible range (380 nm-780 nm), before and after aging, from % Pigment (%P1, %P2, %P3 and %P4) within the formulation. Results The average value of the prediction error of the model was 3.46% (SD: 1.82) across all wavelengths for samples before aging and 3.54% (SD: 1.17) for samples after aging. The differences found between the predicted and measured values of the chromatic coordinates are smaller than the acceptability threshold and, in some cases, are even below the perceptibility threshold. Conclusions Within the framework of this pilot study, the nonlinear predictive models developed allow the prediction, with a high degree of accuracy, of the reflectance spectrum of the experimental dental resin composites. PMID:26329369

  19. Effect of resealing on microleakage of resin composite restorations in relationship to margin design and composite type

    PubMed Central

    Antonson, Sibel A.; Yazici, A. Ruya; Okte, Zeynep; Villalta, Patricia; Antonson, Donald E.; Hardigan, Patrick C.

    2012-01-01

    Objective: To determine the relationship between margin preparation design and resin-composite type on microleakage with or without re-application of surface-penetrating sealant. Methods: Class-I resin-composite restorations were completed for 128 extracted human molars. Half of the margins were beveled, the other half, butt-joint. Half of each group was restored with Filtek-Supreme (FS), the other half with Esthet-X (EX) using their respective adhesive systems. Margins were etched and sealed with a surface-penetrating sealant, Fortify. The samples were stored in water 24h, and thermocycled (5,000 cycles, 5°C–55°C). Then, samples were abraded using a toothbrush machine (6,000 strokes). Half of the restorations from each sealant group (n=16) were resealed, and the other half had no further treatment. Thermocycling and tooth brushing were repeated. The samples were sealed with nail polish, immersed in methylene-blue for 8h, sectioned, and magnified digital photographs were taken. Three examiners assessed dye penetration. A 2×2×2 multi-layered Chi-Square analysis, using Cochran-Mantel-Haenszel test was conducted for statistical analysis. Results: No difference was observed between sealed and resealed FS and EX restorations with butt-joint margins. In beveled margins, resealing caused significantly less microleakage (P<.01). No differences were found between restorations either sealed or resealed with bevel margins. In butt-joint margins, at the leakage level deeper than 2/3 of the preparation depth, resealed FS showed less microleakage than EX resealed restorations (P<.01). Conclusion: Resealing reduced microleakage in bevel margins, however, in butt-joint margins resealing did not affect the leakage. A significant statistical relationship exists between and within resealing, margin preparation design, type of composite, and microleakage. PMID:23077418

  20. Shear test of composite bonded to dentin: Er:YAG laser versus dental handpiece preparations

    NASA Astrophysics Data System (ADS)

    Visuri, Steven R.; Gilbert, Jeremy L.; Walsh, Joseph T., Jr.; Wigdor, Harvey A.

    1995-05-01

    The erbium:YAG laser coupled with a cooling stream of water appears to be an effective means of removing dental hard tissues. However, before the procedure is deemed clinically viable, there are several important issues of safety and efficacy that need to be explored. In this study we investigated the surface that remains following laser ablation of dentin and compared the results to the use of a dental handpiece. Specifically, we studied the effect the laser radiation had on the bonding of composite to dentin. The crowns of extracted human molars were removed revealing the underlying dentin. An additional thickness of material was removed with either a dental handpiece or an Er:YAG laser by raster scanning the samples under a fixed handpiece or laser. Comparable surface roughnesses were achieved. A cylinder of composite was bonded onto the prepared surfaces following the manufacturer's directions. The dentin-composite bond was then shear stressed to failure on a universal testing apparatus and the maximum load recorded. Preliminary results indicated that laser irradiated samples had improved bond strengths. SEM photographs of the surfaces were also taken to compare the two methods of tooth preparation.

  1. Effect of immersion in various media on the sorption, solubility, elution of unreacted monomers, and flexural properties of two model dental composite compositions.

    PubMed

    Zhang, Yujie; Xu, Jingwei

    2008-06-01

    Immersion in various media has different effect on the properties of dental composites, such as sorption, solubility, elution of unreacted monomers, flexural strength, and flexural elastic modulus. In the present work, the effect of immersion in various media and the relationship between the variation of these properties and the components of dental composite were investigated. Two model dental composites were immersed in three different media-distilled water, artificial saliva, and ethanol/water, respectively, for a certain time. Their sorption, solubility, flexural strength, and flexural elastic modulus were tested according to the international standard. Elution of unreacted monomers was analyzed by using high performance liquid chromatography (HPLC) and the surface morphology of samples after immersion was observed using scanning electron microscope (SEM). The results showed that the effect on properties depended on the immersion media where ethanol/water had the most significant effect and these properties were related to the components of dental composite. PMID:18253815

  2. Dental composite polymerization: a three different sources comparison

    NASA Astrophysics Data System (ADS)

    Sozzi, Michele; Fornaini, Carlo; Lagori, Giuseppe; Merigo, Elisabetta; Cucinotta, Annamaria; Vescovi, Paolo; Selleri, Stefano

    2015-02-01

    The introduction of photo-activators, with absorption spectra in the violet region, in composite resins raised interest in the use of 405 nm diode lasers for polymerization. The purpose of this research is the evaluation of the resins polymerization by means of violet diode laser compared to traditional lamps. Two different resins have been used for the experiments: Filtek Supreme XT flow (3M ESPE, USA) and Tetric Evo flow (Ivoclar, Vivadent). The photo-activator used is Camphoroquinone, alone, or in combination with Lucirin TPO. The resins have been cured with an halogen lamp (Heliolux DXL, Vivadent Ivoclar, Austria), a broadband LED curing light (Valo Ultradent, USA) and a 405 nm laser (Euphoton, Italy). The measure of cure depth, of the volumetric shrinkage, and the conversion degree (DC%) of the double bond during the curing process have been evaluated. A composite layer of 3 mm was cured in Filtek Supreme resin (Camphoroquinone activator), lower if compared to the use of the other two light sources. Tests on Tetric Evo (Camphoroquinone + Lucirin) didn't show any improvement of the use of laser compared to the halogen lamp and the broadband LED. By measuring the volumetric shrinkage the laser induced the lower change with both the composites. In terms of DC% the lower performance was obtained with the laser. Considering that the polymerization process strongly depends on the kind of composite used the effectiveness of 405 nm laser proved to be lower than halogen lamps and broadband LEDs.

  3. The effect of CO2 laser irradiation plus fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement or composite resin restorations

    NASA Astrophysics Data System (ADS)

    Rodrigues, S. R.; Moraes, M.; Hanashiro, F. S.; Youssef, M. N.; Brugnera Junior, A.; Nobre-dos-Santos, M.; de Souza-Zaroni, W. C.

    2016-02-01

    Although the cariostatic effects of CO2 laser on the root surface have been shown, there is scarce information regarding its effects on root secondary caries. The objective of this research was to investigate the effect of the association of CO2 laser and a fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to composite-resin or glass-ionomer-cement restorations. Dental blocks of human roots were divided into two groups: composite resin (CR) or glass ionomer cement (GIC). Subsequently, the blocks were divided into four subgroups (n  =  10): C, non-fluoride dentifrice; FD, fluoride dentifrice; L, CO2 laser with an energy density of 6.0 J cm-2  +  non-fluoride dentifrice; and L  +  FD, CO2 laser  +  fluoride dentifrice. The blocks were subjected to pH cycling to simulate a high cariogenic challenge. Dental demineralization around the restorations was quantified by microhardness analysis. The results were subjected to analysis of variance (ANOVA) and the Tukey-Kramer test (p  ⩽  0.05). As for mineral loss, it can be observed that all the groups that were treated with a fluoride dentifrice and laser, used alone or not, were statistically similar and superior to the RC-C group. It was concluded that CO2 laser irradiation and a fluoride dentifrice used alone or combined with each other are efficient surface treatments for preventing secondary root caries, regardless of the restorative material used.

  4. Fatigue of restorative materials.

    PubMed

    Baran, G; Boberick, K; McCool, J

    2001-01-01

    Failure due to fatigue manifests itself in dental prostheses and restorations as wear, fractured margins, delaminated coatings, and bulk fracture. Mechanisms responsible for fatigue-induced failure depend on material ductility: Brittle materials are susceptible to catastrophic failure, while ductile materials utilize their plasticity to reduce stress concentrations at the crack tip. Because of the expense associated with the replacement of failed restorations, there is a strong desire on the part of basic scientists and clinicians to evaluate the resistance of materials to fatigue in laboratory tests. Test variables include fatigue-loading mode and test environment, such as soaking in water. The outcome variable is typically fracture strength, and these data typically fit the Weibull distribution. Analysis of fatigue data permits predictive inferences to be made concerning the survival of structures fabricated from restorative materials under specified loading conditions. Although many dental-restorative materials are routinely evaluated, only limited use has been made of fatigue data collected in vitro: Wear of materials and the survival of porcelain restorations has been modeled by both fracture mechanics and probabilistic approaches. A need still exists for a clinical failure database and for the development of valid test methods for the evaluation of composite materials. PMID:11603506

  5. The Evaluation of Various Restoration Techniques on Internal Adaptation of Composites in Class V Cavities

    PubMed Central

    Dionysopoulos, D.; Papadopoulos, C.; Koliniotou-Koumpia, E.

    2014-01-01

    Aim. The aim of this study was to evaluate the effect of different restoration techniques on the formation of internal microgaps between materials and dentin in class V restorations. Materials and Methods. Twenty-five extracted human premolars were prepared with standardized class V cavity outlines (3 mm × 2 mm × 2 mm). The cavities were randomly divided into 5 groups of 10 cavities each and restored according to manufacturer's instructions: Group 1: preheating (55°C) conventional composite (Filtek Z250), Group 2: flowable composite (Filtek Flow), Group 3: Filtek Flow + Filtek Z250 light-cured separately, Group 4: Filtek Flow + Filtek Z250 light-cured simultaneously, and Group 5 (control): Filtek Z250 at room temperature (23°C). The specimens were then thermocycled and cross-sectioned through the center of the restoration. Subsequently, impressions were taken, and epoxy resin replicas were made. The internal adaptation of the materials to the axial wall was analyzed under SEM. Results. The preheated Filtek Z250 (Group 1) showed better internal adaptation than the room temperature groups (P < 0.05). The combination of Filtek Flow with Filtek Z250 which was light-cured separately (Group 3) exhibited better internal adaptation than control group (P < 0.05). Conclusion. Different restoration techniques exhibit different behavior regarding internal adaptation to dentin after photopolymerization. PMID:25349611

  6. Influence of adhesive system and bevel preparation on fracture strength of teeth restored with composite resin.

    PubMed

    Coelho-de-Souza, Fábio Herrmann; Rocha, Analice da Cunha; Rubini, Alessandro; Klein-Júnior, Celso Afonso; Demarco, Flávio Fernando

    2010-01-01

    The aim of this study was to evaluate the fracture strength of teeth with different cavosurface margin cavity preparations and restored with composite resin and different adhesive systems. Eighty premolars were randomly divided in 8 groups, as follow: G1- sound teeth; G2- MOD preparation (no restoration); G3- Adper Single Bond without bevel preparation (butt joint); G4- Adper Single Bond with bevel preparation; G5- Adper Single Bond with chamfer preparation; G6- Clearfil SE Bond without bevel (butt joint); G7- Clearfil SE Bond with bevel preparation; G8- Clearfil SE Bond with chamfer preparation. The adhesive systems were applied according to manufacturers' instructions. Composite resin (Filtek Z250) was incrementally placed in all cavities. After 24 h, the specimens were tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test (fracture strength) and Fisher's exact test (fracture pattern). The confidence level was set at 95% for all tests. Prepared and non-restored teeth showed the worst performance and G4 exhibited the highest fracture strength among all groups (p<0.05). In conclusion, all restorative treatments were able to recover the fracture strength of non-restored teeth to levels similar to those of sound teeth. Using a total-etch adhesive system with bevel preparation significantly improved the resistance to fracture. PMID:20976383

  7. Marginal leakage of class II glass ionomer-composite resin restorations: an in vitro study.

    PubMed

    Hirschfeld, Z; Frenkel, A; Zyskind, D; Fuks, A

    1992-02-01

    This in vitro study assessed the sealing properties of two metal-reinforced glass ionomer cements, used as "extended bases" in glass ionomer-composite resin restorations. Two class II cavities were prepared in the proximal surfaces of 30 molars. The gingival margin of one was prepared in enamel and the other in cementum/dentin. Fifteen teeth (30 cavities) were restored with Ketac Silver material used as an extended base (group A). In the remaining 15 teeth (30 cavities), the extended base was in Miracle Mix material (group B). All occlusal surfaces were restored with Estilux Posterior Material. The restored teeth were thermocycled, immersed in fuchsin, washed in water, embedded, sectioned, and examined under a dissecting microscope. All restorations with margins in cementum/dentin of group A (Ketac Silver) leaked. No microleakage occurred in 12 of the 30 restorations with margins in cementum/dentin of group B (Miracle Mix). In addition, severe microleakage was present in 24 teeth of group A, as opposed to three in group B. It was concluded that the sealing properties of Miracle Mix material are superior to those of Ketac Silver material, in vitro. PMID:1538319

  8. Microcomputed tomographic comparison of posterior composite resin restorative techniques: sonicated bulk fill versus incremental fill.

    PubMed

    Jarisch, Justin; Lien, Wen; Guevara, Peter H; Greenwood, William J; Dunn, William J

    2016-01-01

    Sonication technology has recently been touted to decrease composite viscosity during delivery and may allow better cavity preparation adaptation and minimize voids. The purpose of this investigation was to evaluate the difference between conventional, hand-placed, incremental application of a standard hybrid resin-based composite (RBC) and sonicated application of a bulk-fill RBC in box-type and cylindrical cavity preparations. Experimental restorations were fabricated using molds of box-type or cylindrical preparations. For bulk-filled specimens, a single compule of bulk-fill composite was dispensed with a sonic handpiece. The conventional hybrid material was placed in 3 increments (2 mm, 2 mm, and 1 mm). Microfocus x-ray computed tomography was used to analyze voids for percentage and total volume porosity as well as number of actual pores. An analysis of variance indicated that RBC restorations that were applied to cylindrical cavities using a sonicated bulk-filled application method exhibited significantly less porosity (1.42%; P < 0.001) than incrementally placed cylindrical restorations (2.87%); sonicated bulk-filled, cube-shaped restorations (3.12%); and incrementally placed cube-shaped restorations (5.16%). When the groups were subcategorized into the specific characteristics of shape (cube vs cylinder) and application method (bulk vs incremental), the cylindrical group, which included both bulk-filled and incrementally placed specimens, demonstrated significantly less porosity (2.00%; P < 0.001) than other groups. Restorations that were incrementally placed into cube-shaped cavities produced the largest amount of porosity. PMID:27599276

  9. Cyclic mechanical loading promotes bacterial penetration along composite restoration marginal gaps

    PubMed Central

    Khvostenko, D.; Salehi, S.; Naleway, S. E.; Hilton, T. J.; Ferracane, J. L.; Mitchell, J. C.; Kruzic, J. J.

    2015-01-01

    Objectives Secondary caries is the most common reason for composite restoration replacement and usually forms between dentin and the filling. The objective of this study was to investigate the combined effect of cyclic loading and bacterial exposure on bacterial penetration into gaps at the interface between dentin and resin composite restorative material using a novel bioreactor system and test specimen design. Methods Human molars were machined into 3 mm thick disks with 2 mm deep × 5 mm diameter cavity preparations into which composite restorations were placed. A ∼15-30 micrometer (small) or ∼300 micrometer wide (large) dentin-restoration gap was introduced along half of the interface between the dentin and restoration. Streptococcus mutans UA 159 biofilms were grown on each sample prior to testing in a bioreactor both with and without cyclic loading. Both groups of samples were tested for 2 weeks and post-test biofilm viability was confirmed with a live-dead assay. Samples were fixed, mounted and cross-sectioned to reveal the gaps and observe the depth of bacterial penetration. Results It was shown that for large gap samples the bacteria easily penetrated to the full depth of the gap independent of loading or non-loading conditions. The results for all cyclically loaded small gap samples show a consistently deep bacterial penetration down 100% of the gap while the average penetration depth was only 67% for the non-loaded samples with only two of six samples reaching 100%. Significance A new bioreactor was developed that allows combining cyclic mechanical loading and bacterial exposure of restored teeth for bacterial biofilm and demineralization studies. Cyclic loading was shown to aid bacterial penetration into narrow marginal gaps, which could ultimately promote secondary caries formation. PMID:25900624

  10. Quantitative evaluation of approximal contacts in Class 2 composite resin restorations: a clinical study.

    PubMed

    Wang, J C; Charbeneau, G T; Gregory, W A; Dennison, J B

    1989-01-01

    The purpose of this study was to develop an accurate and reproducible intraoral method of measuring the distance between two teeth, and to conduct a clinical pilot study of the effect of placement of a class 2 posterior resin restoration upon this intertooth dimension. A Kaman Sciences KD-2611 noncontact displacement measuring system with a 1U unshielding sensor, based upon the variable resistance of eddy current, was used for the intraoral measurement. Seven patients requiring conservative interproximal restorations (initial placements or replacements) on the premolars were selected. Addition silicone impressions were taken of the posterior quadrants from which low-fusing metal (Cerrolow-136) casts were made. Composite resin copings constructed on modified rubber dam clamps were fabricated for the restoration and adjacent teeth upon these metal casts. Aluminum targets and Plexiglas holders for the sensor were attached to the bow of the rubber dam clamp with light-activated composite resin. Quantitative measurements of intertooth distance were made preoperatively, postoperatively, and at one-week and 4 1/2-month recalls after placement of class 2 composite resin restorations for 11 teeth. Four unrestored premolars served as a control. The data were tabulated and analyzed using one-way analysis of variance. The results indicated that the mean postoperative intercoping distance for restored teeth increased after a multiple wedging technique had been applied during restorative procedure. At the one-week recall, these distances had decreased. The 4 1/2-month measurements showed a further decrease with an average loss of 15 microns from the preoperative baseline. PMID:2639320

  11. Dynamic measurement of local displacements within curing resin-based dental composite using optical coherence elastography

    NASA Astrophysics Data System (ADS)

    Tomlins, Peter H.; Rahman, Mohammed Wahidur; Donnan, Robert S.

    2016-04-01

    This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ˜1 to 2 μm, enabling submicrometer time-varying displacements to be detected.

  12. Effects of pulp capping materials on fracture resistance of Class II composite restorations

    PubMed Central

    Kucukyilmaz, Ebru; Yasa, Bilal; Akcay, Merve; Savas, Selcuk; Kavrik, Fevzi

    2015-01-01

    Objective: The aim of this study was to investigate the effect of cavity design and the type of pulp capping materials on the fracture resistance of Class II composite restorations. Materials and Methods: Sixty freshly extracted, sound molar teeth were selected for the study. A dovetail cavity on the mesio-occlusal and a slot cavity on disto-occlusal surfaces of each tooth were prepared, and the teeth were divided 4 groups which one of them as a control group. The pulp capping materials (TheraCal LC, Calcimol LC, Dycal) applied on pulpo-axial wall of each cavity, and the restoration was completed with composite resin. The teeth were subjected to a compressive load in a universal mechanical testing machine. The surfaces of the tooth and restoration were examined under a stereomicroscope. The data were analyzed using factorial analysis of variance and Tukey's test. Results: For pulp capping materials, the highest fracture load (931.15 ± 203.81 N) and the lowest fracture load (832.28 ± 245.75 N) were calculated for Control and Dycal group, respectively. However, there were no statistically significant differences among all groups (P > 0.05). The fracture load of the dovetail groups was significantly higher than those of the slot cavity groups (P < 0.05). Conclusion: Dovetail cavity design shows better fracture resistance in Class II composite restorations, independent of used or not used pulp capping materials. PMID:26038653

  13. Influence of cavity design on the biomechanics of direct composite resin restorations in Class IV preparations.

    PubMed

    Xu, Haiping; Jiang, Zhe; Xiao, Ximei; Fu, Jing; Su, Qin

    2012-04-01

    This study evaluated the effect of cavity design on stress distribution and fracture resistance of direct composite resin restorations in Class IV preparations. A finite element analysis (FEA) model of the maxillary central incisor with a Class IV cavity was established. Five model variations were studied: (i) a 1-mm bevel (ii) a 2-mm bevel, (iii) a plain chamfer, (iv) a stair-step chamfer, and (v) butt joints (a control configuration). All FEA variations modeled a tooth restored with composite resin loaded under 100 N at an angle of 45° to the longitudinal axis. The interfacial von Mises stress was evaluated. The FEA was complemented with an in vitro assessment. Fracture resistance of direct composite resin restorations was tested with a universal testing machine and fracture patterns were observed. Finite element analysis showed that stress in chamfer and stair-step chamfer models was more homogenously distributed, while stress in bevel models was relatively concentrated at lingual regions. Fracture resistance of a 1-mm bevel preparation was lower than for the 2-mm bevel, plain chamfer, and stair-step chamfer preparations, but was higher than for butt joints. The stair-step chamfer group presented the most favorable failure pattern. Considering biomechanics and esthetics, the present study indicates that the stair-step chamfer and 2-mm bevel should be recommended for clinical restoration. PMID:22409223

  14. The effect of retention grooves on gingival marginal leakage in Class II posterior composite resin restorations.

    PubMed

    Ben-Amar, A; Liberman, R; Nordenberg, D; Metzger, Z

    1988-07-01

    In this laboratory study, the effect of retention grooves in the proximal portion of class II cavities on the marginal microleakage using light-cured composite resin was examined. The retention grooves were placed at the axio-facial and axio-lingual line angles and in the gingival floor of the cavities. The teeth were restored with Herculite composite resin with etching and dentine bonding and polymerized in two different ways: (i) a single mass of restorative material was polymerized all at once; and (ii) incrementally placed amounts of restorative material were each polymerized separately until the cavity was completely filled. Marginal microleakage was evaluated by the degree of dye penetration at the gingival margin of the restorations after suitable thermocycling procedures. It was concluded that marginal microleakage was significantly reduced when the composite resin was placed and polymerized incrementally, and that no advantage was gained from retention grooves with this incremental technique. However, when polymerizing in one single mass of material, retention grooves were found to be necessary in order to reduce marginal microleakage at the gingival wall. PMID:3171754

  15. Biologic restoration: the effects of composite inlays on patient treatment plans.

    PubMed

    Bottacchiari, Stefano; De Paoli, Sergio; Bottacchiari, Paul A

    2011-04-01

    A technique for restoration of decayed and fractured teeth with composite inlays or onlays is presented. This approach conserves the tooth structure, requires less preprosthetic periodontal surgical intervention, and provides excellent functional results, while minimizing the incidence of post-therapeutic endodontic involvement. Two thousand seven teeth were restored using this technique over a period of 120 months, with a mean time of 59.6 months in function. The technique is described, and the advantages of this treatment modality are discussed. PMID:21491010

  16. Finite element analysis of weakened roots restored with composite resin and posts.

    PubMed

    Coelho, Carla Santina de Miranda; Biffi, João Carlos Gabrielli; Silva, Gisele Rodrigues da; Abrahão, Anthony; Campos, Roberto Elias; Soares, Carlos José

    2009-11-01

    Finite element analysis (FEA) was used to investigate the influence of different post systems on the stress distribution of weakened teeth under oblique-load application. A maxillary central incisor root obtained from a sound tooth was weakened by partial removal of dentin inside the root canal. Seven two-dimensional numerical models, one from the sound tooth and six from the weakened root restored with composite resin and post systems were created as follows - ST: sound tooth; CPC: cast CuAl post and core; SSP: stainless steel post + composite core; GP: fiberglass + composite core; CP: carbon fiber + composite core; ZP: zirconium dioxide post + composite core; TP: titanium post + composite core. The numerical models were considered to be restored with a leucite-reinforced all-ceramic crown and received a 45 masculine occlusal load (10 N) on the lingual surface.All the materials and structures were considered linear elastic, homogeneous, and isotropic, with the exception of fiberglass and carbon fiber posts which assumed orthotropic behavior. The numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using von Mises and Sy stress criteria. When compared with the sound tooth, FEA revealed differences in stress distribution when post systems were used. Among the restored teeth, the use of CPC, SSP, ZP, and TP resulted in higher stress concentration in the post itself when compared to GP and CP. Therefore, results from the FEA images suggested that the use of non-metallic post systems could result in improved mechanical behavior for the weakened restored teeth. PMID:20019417

  17. An in vitro microleakage study of class V cavities restored with a new self-adhesive flowable composite resin versus different flowable materials

    PubMed Central

    Sadeghi, Mostafa

    2012-01-01

    Background: Regarding the importance of sealing ability of restorative dental materials, this study was done to assess the microleakage of class V cavities restored with a new self-adhesive flowable composite resin and compare to different flowable materials. Materials and Methods: Seventy standardized class V cavities were prepared on the buccal surface of maxillary premolars teeth. The occlusal and the gingival margins of the cavities were located on the enamel and cementum/dentin, respectively. Teeth were randomly assigned into five groups (n = 14) and restored with different flowable materials following the manufacturer's instructions: groups I and II: EMBRACE WetBond flowable composite resin with and without acid etching and bonding agent, respectively; group III: flowable compomer (Dyract Flow); and IV and V: microhybrid (Tetric Flow) and nanofilled (Premise Flowable) flowable composite resins, respectively. After finishing and polishing, the teeth were stored in distilled water at 37°C, thermocycled, coated with nail varnish, and immersed in a basic fuchsin, and then longitudinally sectioned. Dye penetration was examined with a stereomicroscope and scored separately for occlusal and gingival on a 0-3 ordinal scale. Data were analyzed with Kruskal-Wallis, Mann-Whitney and Wilcoxon tests (α=0.05). Results: EMBRACE WetBond with acid etching and bonding agent had significantly less microleakage at the occlusal margins than those without, but not at cervical margins. Also cavities restored with EMBRACE WetBond without acid etching and bonding agent showed significantly greater microleakage scores than other groups at occlusal margin, but there was no significant difference at the cervical margin. Conclusion: The application of acid etching and bonding agent with EMBRACE WetBond provided better occlusal marginal sealing than those without at class V cavities. PMID:23162589

  18. Acoustic emissions generated in aged dental composites using a laser thermoacoustic technique.

    PubMed

    Lee, S Y; Lin, C T; Dong, D R; Huang, H M; Shih, Y H

    2000-09-01

    The heating up of dental composites by laser will produce acoustic emissions (AEs) that may be related to fracture mechanisms in the composites. It has been proved that the mechanical properties of dental composites are affected by storage in food simulating liquids, i.e. 75% ethanol, which has a solubility parameter approximating to that of bisphenol glycidyl dimethacrylate (BisGMA) resin. A new method was innovated to evaluate the laser-induced AEs in dental composites aged by 75% ethanol solution. Model systems (50/50 BisGMA/TEGDMA resin filled with 0% and 75 wt.% 5-10 microm silanized BaSiO6) as well as three commercial composites (Marathon One, Z100 and Herculite XRV) were used in this study. Nine samples acting as the control group were tested to establish the correlation of AEs to laser power. The effect of ageing by immersion in 75% ethanol on AEs and diametral tensile strength (DTS) was then evaluated. A quasi-continuous wave CO2 laser was used to heat up the composites. AEs of frequency 100-200 kHz were collected, filtered, recorded and processed using a 4610 Smart Acoustic Monitor. Burst patterns, which formally were assumed to be correlated to fracture mechanisms, were also identified from the data obtained at laser power > or = 5 W for commercial composites and > or = 4 W for model systems. Higher laser powers cause the AE to increase for all composites except unfilled model resin. AEs as a function of power for all aged systems were flat (< 100 events) below 4 W. Emissions then rose sharply to > 1000 events at 7.1 W. Statistically significant differences were found between the AEs obtained at 5 W (commercial composites) and those at 4.3 W (model systems) for material systems and storage times. Marathon One was less affected by the laser and an abrupt change in AE was found between days 0 and 7 of storage for all commercial composites. The AE value from the unfilled model resin was found to be significantly different from that of the model composites

  19. N-vinylpyrrolidone modified glass-ionomer resins for improved dental restoratives

    NASA Astrophysics Data System (ADS)

    Xie, Dong

    :IA:NVP) was considered as the best molar ratio for these copolymers, based on the DTS and CS tests. The fifth study formulated the NVP-containing RM GICs using a statistical design of experiment. The results indicated that the best graft ratio for 2-isocyanatoethyl methacrylate (IEM) in this system was 15% of the terpolymer by a molar ratio. The optimal formulation was found to be at the weight ratio of 55:15:30 (RM NVP-containing terpolymer: 2-hydroxyethyl methacrylate (HEMA): Hsb2O). Stress-strain curves showed that a relatively high amount of water in the formulation led to higher elastic modulus and proportional limit and lower malleability, whereas a relatively high amount of HEMA gave the opposite results. The sixth study evaluated the NVP modified GICs (NVPM GICs) with the best molar ratios and optimal formulations in the mechanical, thermal and working properties. The results showed that the effect of molecular weight on mechanical properties of the NVPM GICs were evident. Different glass powders exhibited different effects on properties of the NVPM GICs, due to different compositions, size and affinity. Powder/liquid ratios had significant effects on the mechanical properties of NVPM GICs, especially on FS. P/W ratios are only beneficial to the NVPM GICs mixed with the Fuji II glass powders. The NVPM GICs showed a higher WT than the models, due to water retention of the NVP ring. Thermal expansion coefficients for the NVPM GICs were close to those for the natural tooth. Mismatch between the glass powders used and the polymer matrix was a big concern in this study and should be solved in the future.

  20. Chemistry of Silanes: Interfaces in Dental Polymers and Composites1

    PubMed Central

    Antonucci, Joseph M.; Dickens, Sabine H.; Fowler, Bruce O.; Xu, Hockin H. K.; McDonough, Walter G.

    2005-01-01

    The performance and service life of glass-or ceramic-filled polymeric composites depend on the nature of their resin, filler and interfacial phases as well as the efficacy of the polymerization process. The synergy that exists between the organic polymer matrix and the usually inorganic reinforcing filler phase is principally mediated by the interfacial/interphasial phase. This latter phase develops as a result of the dual reactivity of a silane coupling agent, (YRSiX3), a bifunctional molecule capable of reacting with the silanol groups of glass or ceramic fillers via its silane functional group (–SiX3) to form Si-O-Si- bonds to filler surfaces, and also with the resin phase by graft copolymerization via its Y functional group, usually a methacrylic vinyl group. In this paper, we explore some of the chemistry of organosilanes, especially that of functional organosilanes (or silane coupling agents as they are commonly known) that are used to mediate interfacial bonding in mineral reinforced polymeric composites. The chemistry of organosilanes can be quite complex involving hydrolytically initiated self-condensation reactions in solvents (including monomers) that can culminate in polymeric silsesquioxane structures, exchange reactions with hydroxylated or carboxylated monomers to form silyl ethers and esters, as well as the formation of silane derived interfaces by adhesive coupling with siliceous mineral surfaces. PMID:27308178

  1. An in vitro evaluation of microleakage in class V preparations restored with Hybrid versus Silorane composites

    PubMed Central

    Umer, Fahad; Naz, Farah; Khan, Farhan Raza

    2011-01-01

    Aim: To compare the difference in microleakage values using conventional and new low-shrink Silorane composites using the dye penetration method. Background: With improvement in adhesive technology, problems associated with composites have been largely overcome. However, microleakage due to polymerization shrinkage still remains a challenge. New Silorane-based composites are alleged to have less than 1% polymerization shrinkage, which would potentially decrease the microleakage, and hence, resolve this longstanding issue. Materials and Methods: The teeth were randomly divided into three groups (A,B, and C). Group A was restored with conventional composite (Valux™ Plus), with a total-etch protocol, Group B was restored with conventional composite, with a self-etch protocol, and group C were restored with a silorane-based composite (Filtek TMP90). Thermocycling at 200 cycles between 5 and 55°C ± 2°C with a dwell time of 60 seconds was conducted. The teeth were stained with methylene blue dye and then sectioned and viewed under a dissection microscope, afer which the microleakage was evaluated. Results: The interexaminer reliability was evaluated using the kappa score, which was acceptable (61 – 78%). The total-etch group performed statistically and significantly better (P < 0.001) at the occlusal margin and was marginally and statistically significant (P = 0.05) at the gingival margin compared to the self-etch conventional and Silorane groups. Conclusions: The Silorane composite did not perform better than the conventional composites, however, it may have its uses and requires further research. PMID:21814346

  2. Mechanochemically synthesized kalsilite based bioactive glass-ceramic composite for dental vaneering

    NASA Astrophysics Data System (ADS)

    Kumar, Pattem Hemanth; Singh, Vinay Kumar; Kumar, Pradeep

    2015-08-01

    Kalsilite glass-ceramic composites have been prepared by a mechanochemical synthesis process for dental veneering application. The aim of the present study is to prepare bioactive kalsilite composite material for application in tissue attachment and sealing of the marginal gap between fixed prosthesis and tooth. Mechanochemical synthesis is used for the preparation of microfine kalsilite glass-ceramic. Low temperature frit and bioglass have been prepared using the traditional quench method. Thermal, microstructural and bioactive properties of the composite material have been examined. The feasibility of the kalsilite to be coated on the base commercial opaque as well as the bioactive behavior of the coated specimen has been confirmed. This study indicates that the prepared kalsilite-based composites show similar structural, morphological and bioactive behavior to that of commercial VITA VMK95 Dentin 1M2.

  3. Dynamic cure measurement of dental polymer composites using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tomlins, Peter H.; Palin, Will M.; Shortall, Adrian C.

    2008-02-01

    Dental amalgam is being increasingly replaced by Light-activated resin-based dental composites. However, these materials are limited by inefficient setting reactions as a function of depth, constraining the maximum extent of cure and reducing biocompatibility. In this paper we demonstrate a novel metrological tool for dynamic monitoring of refractive index and thickness change through curing resins using spectral-domain optical coherence tomography. We present real-time measurements from pre- to post-cure of a series of un-filled bisphenol-A diglycidyl ether dimethacrylate (bisGMA) and triethylene glycol dimethacrylate (TEGDMA) resins with different inhibitor concentrations. Our results demonstrate that refractive index measurements are sensitive to the extent of cure of such resins and that the inhibitor concentration strongly affects the cure dynamics and final extent of cure.

  4. Quantitative determination of TEGDMA, BHT, and DMABEE in eluates from polymerized resin-based dental restorative materials by use of GC/MS.

    PubMed

    Seiss, Mario; Langer, Christopher; Hickel, Reinhard; Reichl, Franz-Xaver

    2009-12-01

    This study investigated the leaching of ingredients from several commercial dental composite resins cured with LED, and immersed in methanol or water for 24 h, respectively. The composites used were: Admira Dentin (VOCO), Artemis Schmelz (Enamel) (Ivoclar Vivadent), Els extra low shrinkage (Saremco Dental), Filtek Supreme XT Dentin (3 M ESPE), Gradia Direct (GC), Venus & Venus flow (Heraeus Kulzer), and XRV Herculite Prodigy Enamel (Kerr). From each dental composite four specimens with defined structure and 100-mg net weight were made. After the polymerization process, according to manufacturer's instructions, the specimens were immersed in either 1 ml water or 1 ml methanol and incubated at 37 degrees C for 24 h. Eluted ingredients triethyleneglycoldimethacrylate (TEGDMA), 2,6-di-tert-butyl-4-methylphenol (BHT), and 4-N,N-dimethylaminobenzoicacidethylester (DMABEE) were detected and quantified using gas chromatography-mass spectrometry (GC-MS). The amounts of the detected analytes from 100 mg polymerized composites ranged between the following values: TEGDMA: 0-0.5 mg (water), 0-1.6 mg (methanol); BHT: 0-0.03 μg (water), 0-0.11 mg (methanol); and DMABEE: 0-0.11 mg (water), 0-1.4 mg (methanol). We conclude from the results that the elution rates into methanol and water differ significantly. Furthermore, it is concluded that all the determined amounts eluting from the composites are far below toxic-relevant concentrations. PMID:19771414

  5. Effect of CO2 laser on root caries inhibition around composite restorations: an in vitro study.

    PubMed

    de Melo, Jociana Bandeira; Hanashiro, Fernando Seishim; Steagall, Washington; Turbino, Miriam Lacalle; Nobre-dos-Santos, Marinês; Youssef, Michel Nicolau; de Souza-Zaroni, Wanessa Christine

    2014-03-01

    The aim of the present study was to investigate the in vitro effect of CO2 laser on the inhibition of root surface demineralization around composite resin restorations. For this purpose, 30 blocks obtained from human molar roots were divided into three groups: group 1 (negative control), cavity prepared with cylindrical diamond bur + acid etching + adhesive + composite resin restoration; group 2, cavity prepared with cylindrical diamond bur + CO2 laser (5.0 J/cm(2)) + acid etching + adhesive + composite resin; and group 3, cavity prepared with cylindrical diamond bur + CO2 laser (6.0 J/cm(2)) + acid etching + adhesive + composite resin. After this procedure, the blocks were submitted to thermal and pH cycling. Root surface demineralization around the restorations was measured by microhardness analysis. The hardness results of the longitudinally sectioned root surface were converted into percentage of mineral volume, which was used to calculate the mineral loss delta Z (ΔZ). The percentage of mineral volume, ΔZ, and the percentage of demineralization inhibition of the groups were statistically analyzed by using analysis of variance and Tukey-Kramer test. The percentage of mineral volume was higher in the irradiated groups up to 80 μm deep. The ΔZ was significantly lower in the irradiated groups than in the control group. The percentage of reduction in demineralization ranged from 19.73 to 29.21 in position 1 (50 μm), and from 24.76 to 26.73 in position 2 (100 μm), when using 6 and 5 J/cm(2), respectively. The CO2 laser was effective in inhibiting root demineralization around composite resin restorations. PMID:23291879

  6. Material and clinical considerations for full-coverage indirect restorations.

    PubMed

    Martin, Margaret P

    2012-11-01

    Because dental ceramics have been used for decades and continuously improved over the years, there is a plethora of information regarding their material characteristics, applications, and contraindications. Each restorative ceramic material demonstrates benefits and disadvantages, making it difficult for dentists to research, retain, and apply the ideal material for individual restorations and/or combination cases. This article outlines the applications and benefits of dental ceramics in general and examines and reviews the current ceramic alternatives available for restorative dentistry today. It also discusses the material composition and properties of a recently introduced new classification of indirect material: resin nano-ceramic. PMID:23577553

  7. A comparative study of sliding wear of nonmetallic dental restorative materials with emphasis on micromechanical wear mechanisms.

    PubMed

    Dupriez, Nataliya Deyneka; von Koeckritz, Ann-Kristin; Kunzelmann, Karl-Heinz

    2015-05-01

    The purpose of this study is to investigate the in vitro tribological behavior of modern nonmetallic restorative materials. Specimen prepared of IPS e.max Press lithium disilicate glass ceramic, IPS Empress Esthetic leucite-reinforced glass ceramic, Everest ZS Blanks yttria-stabilized zirconia and Lava Ultimate composite were subjected to wear using a wear machine designed to simulate occlusal loads. The wear of the investigated materials and antagonists were evaluated by a three-dimensional surface scanner. The quantitative wear test results were used to compare and rank the materials. Specimens were divided into two groups with steatite and alumina antagonists. For each antagonist material an analysis of variance was applied. As a post hoc test of the significant differences, Tukey's honest significant difference test was used. With steatite antagonist: wear of zirconia < wear of leucite-reinforced ceramic < wear of lithium disilicate ceramic < wear of Lava Ultimate composite. No significant wear difference was found for steatite antagonist. The wear of IPS e.max Press and Lava Ultimate against hard alumina was found to be twice lower as compared to their wear when opposing to steatite. The differences were associated with materials mechanical properties (hardness and fracture toughness) and with materials microstructure. Wear mechanisms are discussed. PMID:25303041

  8. Reduction of bacterial adhesion on dental composite resins by silicon-oxygen thin film coatings.

    PubMed

    Mandracci, Pietro; Mussano, Federico; Ceruti, Paola; Pirri, Candido F; Carossa, Stefano

    2015-02-01

    Adhesion of bacteria on dental materials can be reduced by modifying the physical and chemical characteristics of their surfaces, either through the application of specific surface treatments or by the deposition of thin film coatings. Since this approach does not rely on the use of drugs or antimicrobial agents embedded in the materials, its duration is not limited by their possible depletion. Moreover it avoids the risks related to possible cytotoxic effects elicited by antibacterial substances released from the surface and diffused in the surrounding tissues. In this work, the adhesion of Streptococcus mutans and Streptococcus mitis was studied on four composite resins, commonly used for manufacturing dental prostheses. The surfaces of dental materials were modified through the deposition of a-SiO(x) thin films by plasma enhanced chemical vapor deposition. The chemical bonding structure of the coatings was analyzed by Fourier-transform infrared spectroscopy. The morphology of the dental materials before and after the coating deposition was assessed by means of optical microscopy and high-resolution mechanical profilometry, while their wettability was investigated by contact angle measurements. The sample roughness was not altered after coating deposition, while a noticeable increase of wettability was detected for all the samples. Also, the adhesion of S. mitis decreased in a statistically significant way on the coated samples, when compared to the uncoated ones, which did not occur for S. mutans. Within the limitations of this study, a-SiO(x) coatings may affect the adhesion of bacteria such as S. mitis, possibly by changing the wettability of the composite resins investigated. PMID:25634298

  9. Adherence of Streptococcus mutans to Fiber-Reinforced Filling Composite and Conventional Restorative Materials

    PubMed Central

    Lassila, Lippo V.J; Garoushi, Sufyan; Tanner, Johanna; Vallittu, Pekka K; Söderling, Eva

    2009-01-01

    Objectives. The aim was to investigate the adhesion of Streptococcus mutans (S. mutans) to a short glass fibers reinforced semi-IPN polymer matrix composite resin. The effect of surface roughness on adhesion was also studied. For comparison, different commercial restorative materials were also evaluated. Materials and Methods. Experimental composite FC resin was prepared by mixing 22.5 wt% of short E-glass fibers, 22.5 wt% of IPN-resin and 55 wt% of silane treated silica fillers using high speed mixing machine. Three direct composite resins (Z250, Grandio and Nulite), resin-modified glass ionomers (Fuji II LC), amalgam (ANA 2000), fiber-reinforced composite (FRC) (everStick and Ribbond), and pre-fabricated ceramic filling insert (Cerana class 1) were tested in this study. Enamel and dentin were used as controls. The specimens (n=3/group) with or without saliva were incubated in a suspension of S. mutans allowing initial adhesion to occur. For the enumeration of cells on the disc surfaces as colony forming units (CFU) the vials with the microbe samples were thoroughly Vortex-treated and after serial dilutions grown anaerobically for 2 days at +37°C on Mitis salivarius agars (Difco) containing bacitracin. Bacterial adhesion was also evaluated by using scanning electron microscopy. Surface roughness (Ra) of the materials was also determined using a surface profilometer. All results were statistically analyzed with one-way analysis of variance (ANOVA). Results. Composite FC resin and other commercial restorative materials showed similar adhesion of S. mutans, while adhesion to dentin and enamel was significantly higher (p<0.05). Surface roughness had no effect on bacterial adhesion. Saliva coating significantly decreased the adhesion for all materials (p<0.05). Composite FC resin had a significantly higher Ra value than control groups (p<0.05). Conclusions. Short fiber-reinforced composite with semi-IPN polymer matrix revealed similar S. mutans adhesion than

  10. Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS)

    PubMed Central

    CORREA, Luciano Ribeiro; BORGES, Alexandre Luiz Souto; GUIMARÃES, Heloisa Bailly; ALMEIDA, Elis Regina Nunes; POSKUS, Laiza Tatiana; SILVA, Eduardo Moreira

    2015-01-01

    Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations. Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS). Material and Methods A base composite (B) was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25). The composites P90 and TPH3 (TP3) were used as positive and negative controls, respectively. Marginal integrity (%MI) was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS) and the polymerization shrinkage stress (Pss - MPa) were also evaluated. Results The values for %MI were as follows: P90 (100%) = TP3 (98.3%) = B (96.9%) > P25 (93.2%), (p<0.05). The %VS ranged from 1.4% (P90) to 4.9% (P25), while Pss ranged from 2.3 MPa (P90) to 3.9 MPa (B). For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa). Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97), whereas the correlation between Pss and %MI was found to be moderate (r=0.76). Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite. PMID:26537714

  11. Adherence of Streptococcus mutans to Fiber-Reinforced Filling Composite and Conventional Restorative Materials.

    PubMed

    Lassila, Lippo V J; Garoushi, Sufyan; Tanner, Johanna; Vallittu, Pekka K; Söderling, Eva

    2009-01-01

    OBJECTIVES.: The aim was to investigate the adhesion of Streptococcus mutans (S. mutans) to a short glass fibers reinforced semi-IPN polymer matrix composite resin. The effect of surface roughness on adhesion was also studied. For comparison, different commercial restorative materials were also evaluated. MATERIALS AND METHODS.: Experimental composite FC resin was prepared by mixing 22.5 wt% of short E-glass fibers, 22.5 wt% of IPN-resin and 55 wt% of silane treated silica fillers using high speed mixing machine. Three direct composite resins (Z250, Grandio and Nulite), resin-modified glass ionomers (Fuji II LC), amalgam (ANA 2000), fiber-reinforced composite (FRC) (everStick and Ribbond), and pre-fabricated ceramic filling insert (Cerana class 1) were tested in this study. Enamel and dentin were used as controls. The specimens (n=3/group) with or without saliva were incubated in a suspension of S. mutans allowing initial adhesion to occur. For the enumeration of cells on the disc surfaces as colony forming units (CFU) the vials with the microbe samples were thoroughly Vortex-treated and after serial dilutions grown anaerobically for 2 days at +37 degrees C on Mitis salivarius agars (Difco) containing bacitracin. Bacterial adhesion was also evaluated by using scanning electron microscopy. Surface roughness (Ra) of the materials was also determined using a surface profilometer. All results were statistically analyzed with one-way analysis of variance (ANOVA). RESULTS.: Composite FC resin and other commercial restorative materials showed similar adhesion of S. mutans, while adhesion to dentin and enamel was significantly higher (p<0.05). Surface roughness had no effect on bacterial adhesion. Saliva coating significantly decreased the adhesion for all materials (p<0.05). Composite FC resin had a significantly higher Ra value than control groups (p<0.05). CONCLUSIONS.: Short fiber-reinforced composite with semi-IPN polymer matrix revealed similar S. mutans adhesion

  12. Effect of three surface sealants on marginal sealing of Class V composite resin restorations.

    PubMed

    Ramos, R P; Chimello, D T; Chinelatti, M A; Dibb, R G; Mondelli, J

    2000-01-01

    This study evaluated in vitro the effectiveness of three different surface sealants (Fortify, Protect-it! and Optiguard) on the marginal sealing of Class V light-activated composite resin restorations (Prodigy). For this purpose, 20 sound noncarious human premolars extracted within a six-month period were selected. Class V cavities with the occlusal margin in enamel and cervical margin in cementum were prepared in both buccal and lingual surfaces. The teeth, randomly assigned in four groups with 10 cavities in each group, were restored with composite resin after applying an adhesive system (Optibond FL). After the finishing and polishing procedures, the restorations were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and immersed in a 50% silver nitrate solution (tracer agent) for eight hours, sectioned longitudinally and analyzed for leakage using an optical microscope in a blind study with three examiners. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the four groups using the Kruskall-Wallis and the Wilcoxon Tests. There was better sealing at the occlusal margin, and in this region, there were no statistically significant differences among the materials (p > 0.05). In the cervical region, Fortify and Protect-it! showed improved results over the Control Group, and Optiguard showed similar results to the Control Group (without sealing). PMID:11203855

  13. Effect of amine activators on the properties of chemical cured dental composites.

    PubMed

    Mathew, L; Joseph, R; Krishnan, V K

    1997-01-01

    The purpose of this study was to evaluate the reactivity and the effect of concentration of three tertiary amines upon the mechanical properties of a chemical curing dental composite. Chemical cured composite pastes were prepared by keeping peroxide concentration constant at 1 wt% (by weight of resin mixture) and by varying the amine/peroxide molar ratio from 0.25 to 1.5. Composite samples were prepared for all three amine pastes aged for 1, 15, 30, 45, and 60 d stored at 8, 22, and 37 degrees C. The loss in activity of the tertiary amine with time was measured. Changes in compressive strength, diametral tensile strength, and microhardness were also measured. A sharp decrease in working and setting times corresponding to increased activity was noticed with an increased amine content. The activity was found to vary in the order N,N-dimethyl p-toluidine (DMPT) > 2-(4-dimethylaminophenyl)ethanol (DMAPEA) > N,Ndiethanol p-toluidine (DEPT). DMPT is found to be more temperature sensitive than DMAPEA and DEPT. However, DEPT is found to provide better storage stability out of all three amines tested. Each amine was found to possess optimum concentrations at which the mechanical properties showed maximum values. DEPT is preferred for long-term storage stability in chemical-cured dental composites where aging tends to reduce the activity of the amine. PMID:9067811

  14. Effect of Different Polymerization Methods on the Cytotoxicity of Dental Composites

    PubMed Central

    Beriat, Nilufer Celebi; Ertan, Ahmet Atila; Canay, Senay; Gurpinar, Aylin; Onur, Mehmet Ali

    2010-01-01

    Objectives: The aim of this study was to compare the cytotoxic effects of various dental composites polymerized with two different curing units. Methods: Disc-shaped test samples of composites Filtek Z250, Filtek A110, Filtek P60, Filtek Supreme, and SDI Rok were polymerized using one quartz tungsten halogen (QTH) and one light emitting diode (LED) light curing unit (LCU), namely Optilux 501 (QTH) and Elipar Freelight 2 (LED). L-929 mouse fibroblast cultures (3x104 cells/ml) were incubated with the samples in 96 well culture plates for evaluation after 8, 24, 48, 72 h. At the end of each period, the cells were counted and examined under a light microscope, and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay was performed. The degree of cytotoxicity for each sample was determined according to the reference value represented by the cells in a control group (a culture without sample). Results: A significant 3 factor interaction occurred among LCUs, composites, and time factors (P<.005). In general, the test materials cured with the LED LCU demonstrated higher cell survival rates when compared with those cured with halogen LCUs. Conclusions: This study shows that polymerization of dental composites with a light emitting diode LCU positively influences the L-929 mouse fibroblast cell viability. PMID:20613917

  15. 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. PMID:22456018

  16. 75 FR 16511 - Pentron Clinical Technologies, a Wholly-Owned Subsidiary of Kerr Dental/Sybron Dental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ... the Federal Register on February 16, 2010 (75 FR 7037). At the request of the State Agency, the... such as dental prosthetics, dental composites, dental impressions, dental adhesives, and other dental... prosthetics, dental composites, dental impressions, dental adhesives, and other dental materials to...

  17. Evaluation of the effect of tooth and dental restoration material on electron dose distribution and production of photon contamination in electron beam radiotherapy.

    PubMed

    Bahreyni Toossi, Mohammad Taghi; Ghorbani, Mahdi; Akbari, Fatemeh; Mehrpouyan, Mohammad; Sobhkhiz Sabet, Leila

    2016-03-01

    The aim of this study is to evaluate the effect of tooth and dental restoration materials on electron dose distribution and photon contamination production in electron beams of a medical linac. This evaluation was performed on 8, 12 and 14 MeV electron beams of a Siemens Primus linac. MCNPX Monte Carlo code was utilized and a 10 × 10 cm(2) applicator was simulated in the cases of tooth and combinations of tooth and Ceramco C3 ceramic veneer, tooth and Eclipse alloy and tooth and amalgam restoration materials in a soft tissue phantom. The relative electron and photon contamination doses were calculated for these materials. The presence of tooth and dental restoration material changed the electron dose distribution and photon contamination in phantom, depending on the type of the restoration material and electron beam's energy. The maximum relative electron dose was 1.07 in the presence of tooth including amalgam for 14 MeV electron beam. When 100.00 cGy was prescribed for the reference point, the maximum absolute electron dose was 105.10 cGy in the presence of amalgam for 12 MeV electron beam and the maximum absolute photon contamination dose was 376.67 μGy for tooth in 14 MeV electron beam. The change in electron dose distribution should be considered in treatment planning, when teeth are irradiated in electron beam radiotherapy. If treatment planning can be performed in such a way that the teeth are excluded from primary irradiation, the potential errors in dose delivery to the tumour and normal tissues can be avoided. PMID:26581762

  18. Long-Term Provisional Bonded Composite Restorations Make Full-Mouth Rehabilitation Possible.

    PubMed

    Wilkins, Ronald G

    2016-05-01

    Full-mouth rehabilitation cases frequently require an extended period to complete. In this case involving a patient who presented with a significant amount of lost tooth structure, treatment featured laboratory-fabricated composite provisional restorations aimed at stabilizing the dentition and enabling definitive treatment to be completed in segments. The approach taken allowed occlusal and esthetic issues to be resolved through use of the provisionals while minimizing tooth preparation. The technique provided immediate improvement in esthetics, function, and comfort. PMID:27213778

  19. The application of indirect composite onlays in the restoration of severely broken down posterior teeth.

    PubMed

    McCarthy, Ray

    2015-12-01

    Increasing interest has developed among dentists regarding alternatives to traditional full-coverage crowns for the restoration of extensively broken-down teeth that are both aesthetic and less destructive of remaining tooth structure. Indirectly fabricated resin composite onlays may offer a viable and cost-effective treatment option in such cases. This paper describes the clinical rationale for resin-based onlays, and includes a case report illustrating the author's experience with the technique to date. PMID:26902075

  20. Sealing capacity of a resin-modified glass-ionomer and resin composite placed in vivo in Class 5 restorations.

    PubMed

    Ferrari, M; Davidson, C L

    1996-01-01

    A 2% methylene blue dye was used to assess the leakage resistance of class 5 resin-modified glass-ionomer and resin composite restorations placed in 17 adults. The teeth were extracted 75 to 90 days after placement of the restorations and immersed for 24 hours in the dye solution. Within 7 days after extraction the teeth were sectioned inciso-apically through the center of the restoration and inspected under a stereomicroscope at X20 to determine the depth of dye penetration. No significant differences between the resin-modified glass-ionomer and resin composite restorations at the incisal or cervical margins were found. Although no more than 30% of the restorations of either group exhibited microleakage, neither of the restorative systems was able to completely prevent leakage at either incisal or cervical margins. PMID:8957921

  1. Effect of In-Office Carbamide Peroxide-Based Tooth Bleaching System on Wear Resistance of Silorane-Based and Methacrylate-Based Dental Composites

    PubMed Central

    Hasani Tabatabaei, Masoumeh; Sheikhzadeh, Sedigheh; Ghasemi Monfared Rad, Hamidreza; Beygi, Ahmad

    2015-01-01

    Objectives: Several studies have assessed the characteristics and properties of silorane-based composites and adhesive systems. Considering the extensive application of tooth-whitening agents, possible deteriorative effects of tooth bleaching agents on these restorative materials must be studied. The aim of this study was to evaluate the effect of an in-office carbamide peroxide-based tooth bleaching agent on the wear resistance of a silorane-based and a conventional microhybrid dimethyl methacrylate-based dental composite with two different application times. Materials and Methods: Thirty cylindrical specimens were made of Z250 and P90 dental composite resins (n=15 for each composite). Samples made of each composite were divided into three groups (n=5) for immersion in an in-office bleaching agent (Opalescence® Quick 45%) for either three or eight hours or saline solution (control). Wear tests were conducted after bleaching using a pin-on disk apparatus under the load of 40N at a constant sliding speed of 0.5 ms−1 for a sliding distance of 300 m. The samples were weighed before and after the wear test. Repeated measures ANOVA was used to statistically analyze the obtained data (α=0.05). Results: There was a significant decrease in the weight of samples after the wear test (P<0.001). However, no significant difference was found among groups in the mean weight of samples before and after the wear test (P>0.05). Conclusion: Bleaching for three or eight hours using 45% carbamide peroxide had no deteriorative effect on the wear resistance of Z250 and P90 composites. PMID:27123014

  2. Effect of Different Prophylaxis Methods on Microleakage of Microfilled Composite Restorations

    PubMed Central

    Kimyai, Soodabeh; Mohammadi, Narmin; Alizadeh Oskoee, Parnian; Pournaghi-Azar, Fatemeh; Ebrahimi Chaharom, Mohammad Esmaeel; Amini, Melina

    2012-01-01

    Background and aims This study was aimed at evaluating the effect of different prophylaxis methods on microleak-age of microfilled composite restorations. Materials and methods In this in vitro study, class V cavities were prepared on buccal surfaces of 84 bovine teeth. The teeth were restored with Tetric N-Bond adhesive and Heliomolar composite resin. Subsequent to a thermocycling procedure and three months of storage in distilled water, the teeth were randomly assigned to four groups (n=21): (1) prophylaxis with a rubber cup and pumice; (2) prophylaxis with a brush and pumice; (3) prophylaxis with air/powder polishing device; and (4) no prophylaxis (the control group). Then the teeth were immersed in 2% basic fuchsin for 24 hours and sectioned for microleakage evaluation under a stereomicroscope. Data were analyzed using Kruskal-Wallis and Wilcoxon Signed Rankstests. Statistical significance was defined at p<0.05. Results There were no statistically significant differences in occlusal and gingival microleakage between the groups (p=0.996 and p=0.860, respectively). In all the groups gingival margins exhibited significantly higher microleakage values compared to occlusal margins (p<0.0005). Conclusion Prophylaxis methods had no adverse effect on marginal leakage of microfilled composite resin restorations. PMID:22991639

  3. Effect of filling technique on the bond strength of methacrylate and silorane-based composite restorations.

    PubMed

    Machado, Fernanda Weingartner; Borges, Fernanda Blos; Cenci, Maximiliano Sérgio; Moraes, Rafael Ratto de; Boscato, Noéli

    2016-01-01

    The bond strength of methacrylate (Z350, 3M ESPE) and silorane (P90, 3M ESPE) restorations, using different cavity filling techniques, was investigated. Cavities (6 × 3 × 3) in bovine teeth were filled using bulk, oblique, or horizontal increments. A push-out test was carried out after 24 h. Data were statistically analyzed (α = 5%). Methacrylate-based composites and the horizontal filling technique showed the highest bond strength values (10.2 ± 3.9, p < 0.05). Silorane-based composites showed no statistically significant differences regarding the filling techniques (p > 0.05). PMID:27050940

  4. Effect of material properties of composite restoration on the strength of the restoration-dentine interface due to polymerization shrinkage, thermal and occlusal loading.

    PubMed

    Borkowski, Krzysztof; Kotousov, Andrei; Kahler, Bill

    2007-07-01

    The purpose of this investigation was to adopt an analytical approach to analyse stresses at the restoration-dentine interface caused by polymerization shrinkage, occlusal and thermal loading with the primary focus on evaluating the effect of the material properties of the composite restoration on the strength of the interface. Some essential simplifications were employed to derive an explicit analytical solution. The results confirm previous findings that interfacial stresses due to polymerization shrinkage are increased with the higher modulus of elasticity of the restoration, while Poisson's ratio of the restorative material has a very small influence on these stresses. Occlusal loading resulted in much lower interfacial stresses when compared to shrinkage and thermal loads. The obtained results were in a good agreement with other numerical and clinical studies. From the modelling analysis it was found that the majority of commercially available composite restorative materials are expected to create significant interfacial stresses when subjected to cold temperatures. In addition, it was shown that there is a considerable potential for interfacial stresses to be minimised by an appropriate selection of thermo-mechanical properties of the restorative material especially with the new finding on the negative temperature variation effect. PMID:17000129

  5. Annual review of selected dental literature: report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry.

    PubMed

    Jendresen, M D; Allen, E P; Bayne, S C; Donovan, T E; Hansson, T L; Klooster, J; Preston, J D

    1993-07-01

    The annual review of selected dental literature this year cites 384 published papers and reports. This year's review contains more editorial comment than reviews of years passed. New data on the biological responses to materials is emphasized in several sections. Observations on new compounds able to prevent plaque formation are presented. Clinically relevant advances in knowledge concerning the etching of different tooth structures are reported along with the effect of etching procedures on the dental pulp. Evaluation of periodontal diseases in all age groups is a topic. Limitations of current diagnostic techniques in periodontal disease, temporomandibular disorders, and implant therapy are included. There are new views on the use of dental amalgam. The future use of dental mercury is predicted. Interest in new ceramic systems is indicated as the demand for esthetics continues. Clinical information is emphasized over scientific information throughout this year's review. PMID:8366458

  6. A new fluorinated urethane dimethacrylate with carboxylic groups for use in dental adhesive compositions.

    PubMed

    Buruiana, Tinca; Melinte, Violeta; Aldea, Horia; Pelin, Irina M; Buruiana, Emil C

    2016-05-01

    A urethane macromer containing hexafluoroisopropylidene, poly(ethylene oxide) and carboxylic moieties (UF-DMA) was synthesized and used in proportions varying between 15 and 35 wt.% (F1-F3) in dental adhesive formulations besides BisGMA, triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The FTIR and (1)H ((13)C) NMR spectra confirmed the chemical structure of the UF-DMA. The experimental adhesives were characterized with regard to the degree of conversion, water sorption/solubility, contact angle, diffusion coefficient, Vickers hardness, and morphology of the crosslinked networks and compared with the specimens containing 10 wt.% hydroxyapatite (HAP) or calcium phosphate (CaP). The conversion degree (after 180 s of irradiation with visible light) ranged from 59.5% (F1) to 74.8% (F3), whereas the water sorption was between 23.15 μg mm(-3) (F1) and 40.52 μg mm(-3) (F3). Upon the addition of HAP or CaP this parameter attained values of 37.82-49.14 μg mm(-3) (F1-F3-HAP) and 34.58-45.56 μg mm(-3), respectively. Also, the formation of resin tags through the infiltration of a dental composition (F3) was visualized by SEM analysis. The results suggest that UF-DMA taken as co-monomer in dental adhesives of acrylic type may provide improved properties in the moist environment of the mouth. PMID:26952402

  7. Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans.

    PubMed

    Beyth, Nurit; Yudovin-Farber, Ira; Bahir, Ran; Domb, Abraham J; Weiss, Ervin I

    2006-07-01

    The antibacterial activity of quaternary ammonium polyethylenimine (PEI) nanoparticles embedded at 1%w/w with clinically used bonding, flowable and hybrid dental composite resins and cured by light polymerization was studied. The antibacterial activity was tested with Streptoccocus mutans by: (i) the agar diffusion test (ADT); (ii) the direct contact test; (iii) bacterial growth in the materials elute; (iv) and scanning electron microscope (SEM). Using the direct contact test, antibacterial activity (p<0.001) was found in all three types of composite resins incorporated with the synthesized nanoparticles. The effect lasted for at least 1 month. SEM demonstrated bacterial debris and no streptococcal chains at 24h of bacterial contact. The addition of 1%w/w of nanoparticles did not affect the flexural modulus and the flexural strength of the dental composite materials. The results indicate that quaternary ammonium PEI nanoparticles immobilized in resin-based materials have a strong antibacterial activity upon contact without leach-out of the nanoparticles and without compromise in mechanical properties. PMID:16564083

  8. Characterization of a Low Shrinkage Dental Composite Containing Bismethylene Spiroorthocarbonate Expanding Monomer

    PubMed Central

    Fu, Jing; Liu, Wenjia; Hao, Zhichao; Wu, Xiangnan; Yin, Jian; Panjiyar, Anil; Liu, Xiaoqing; Shen, Jiefei; Wang, Hang

    2014-01-01

    In this study, a novel dental composite based on the unsaturated bismethylene spiroorthocarbonate expanding monomer 3,9-dimethylene-1,3,5,7-tetraoxa-spiro[5,5]undecane (BMSOC) and bisphenol-S-bis(3-meth acrylate-2-hydroxypropyl)ether (BisS-GMA) was prepared. CQ (camphorquinone) of 1 wt % and DMAEMA (2-(dimethylamino)ethyl methacrylate) of 2 wt % were used in a photoinitiation system to initiate the copolymerization of the matrix resins. Distilled water contact angle measurements were performed for the wettability measurement. Degree of conversion, volumetric shrinkage, contraction stress and compressive strength were measured using Fourier Transformation Infrared-FTIR spectroscopy, the AccuVol and a universal testing machine, respectively. Within the limitations of this study, it can be concluded that the resin composites modified by bismethylene spiroorthocarbonate and BisS-GMA showed a low volumetric shrinkage at 1.25% and a higher contact angle. The lower contraction stress, higher degree of conversion and compressive strength of the novel dental composites were also observed. PMID:24518683

  9. Characterization of a low shrinkage dental composite containing bismethylene spiroorthocarbonate expanding monomer.

    PubMed

    Fu, Jing; Liu, Wenjia; Hao, Zhichao; Wu, Xiangnan; Yin, Jian; Panjiyar, Anil; Liu, Xiaoqing; Shen, Jiefei; Wang, Hang

    2014-01-01

    In this study, a novel dental composite based on the unsaturated bismethylene spiroorthocarbonate expanding monomer 3,9-dimethylene-1,3,5,7-tetraoxa-spiro[5,5]undecane (BMSOC) and bisphenol-S-bis(3-meth acrylate-2-hydroxypropyl)ether (BisS-GMA) was prepared. CQ (camphorquinone) of 1 wt % and DMAEMA (2-(dimethylamino)ethyl methacrylate) of 2 wt % were used in a photoinitiation system to initiate the copolymerization of the matrix resins. Distilled water contact angle measurements were performed for the wettability measurement. Degree of conversion, volumetric shrinkage, contraction stress and compressive strength were measured using Fourier Transformation Infrared-FTIR spectroscopy, the AccuVol and a universal testing machine, respectively. Within the limitations of this study, it can be concluded that the resin composites modified by bismethylene spiroorthocarbonate and BisS-GMA showed a low volumetric shrinkage at 1.25% and a higher contact angle. The lower contraction stress, higher degree of conversion and compressive strength of the novel dental composites were also observed. PMID:24518683

  10. Deposition of lead and cadmium released by cigarette smoke in dental structures and resin composite.

    PubMed

    Takeuchi, Cristina Yoshie Garcia; Corrêa-Afonso, Alessandra Marques; Pedrazzi, Hamilton; Dinelli, Welingtom; Palma-Dibb, Regina Guenka

    2011-03-01

    Cigarette smoke is a significant source of cadmium, lead, and toxic elements, which are absorbed into the human organism. In this context, the aim of this study was to investigate in vitro the presence of toxic elements, cadmium, and lead deriving from cigarette smoke in the resin composite, dentine, and dental enamel. Eight cylindrical specimens were fabricated from resin composite, bovine enamel, and root dentin fragments that were wet ground and polished with abrasive paper to obtain sections with 6-mm diameter and 2-mm thickness. All specimens were exposed to the smoke of 10 cigarettes/day during 8 days. After the simulation of the cigarette smoke, the specimens were examined with scanning electron microscopy (SEM) and the energy-dispersive X-ray analysis. In the photomicrographic analysis in SEM, no morphological alterations were found; however, the microanalysis identified the presence of cadmium, arsenic, and lead in the different specimens. These findings suggest that the deposition of these elements derived from cigarette smoke could be favored by dental structures and resin composite. PMID:20687130

  11. Differences in microbiological composition of saliva and dental plaque in subjects with different drinking habits.

    PubMed

    Signoretto, Caterina; Burlacchini, Gloria; Bianchi, Franco; Cavalleri, Giacomo; Canepari, Pietro

    2006-10-01

    Several foods have been shown to contain natural components (especially polyphenols) which display anti-adhesive properties against Streptococcus mutans, the aetiological agent responsible for dental crown caries, as well as inhibition of glucosyltransferases, which are the S. mutans enzymes involved in the synthesis of an adherent, water-insoluble glucan from sucrose. Other studies have demonstrated an in vitro action on oral plaque biofilm formation and desorption. This study evaluated whether the activity displayed in vitro by food compounds could affect the microbiological composition of saliva and dental plaque of subjects with a diet rich in these foods, comparing the results with those obtained from subjects with a different diet. The foods considered were: coffee, barley coffee, tea and wine. A total of 93 subjects were recruited into the study. Six samples of both plaque and saliva were collected from each subject at roughly one-monthly intervals. Total bacteria, total streptococci, S. mutans and lactobacilli counts were determined by culture in both saliva and dental plaque. The highest bacterial titres were recorded for the control population, while each drinking habit subgroup showed counts roughly one log lower than the controls. These differences in bacterial counts proved statistically significant (P<0.05). As far as dental plaque was concerned, while total counts did not significantly vary per mg of plaque in the subjects belonging to the different drinking habit subgroups, a significant decrease (P<0.05) was observed in those subjects drinking coffee, tea, barley coffee and wine when mutans streptococci and lactobacilli were evaluated. In several cases a more than one log decrease was observed. Plaque indices were also determined, and a significant (P<0.05) reduction in values was recorded in the subjects belonging the specific drinking habit subgroups compared to the control group. This study indicates that there is a correlation between

  12. Resin composite restoration in primary anterior teeth using short-post technique and strip crowns: a case report.

    PubMed

    Mendes, Fausto Medeiros; De Benedetto, Monique Saveriano; del Conte Zardetto, Cristina Giovannetti; Wanderley, Marcia Turolla; Correa, Maria Salete Nahás Pires

    2004-10-01

    A case report describing a technique for the restoration of endodontically treated primary maxillary incisors with resin composite short posts and celluloid strip crowns in a 3-year-old boy is presented. The technique offers the advantages of using one restorative material, improving esthetics, and reducing chairtime and costs. PMID:15470991

  13. Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

    PubMed Central

    CASSELLI, Denise Sá Maia; FARIA-E-SILVA, André Luis; CASSELLI, Henrique; MARTINS, Luis Roberto Marcondes

    2013-01-01

    Objective: This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations. Material and Methods: Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5ºC±2ºC followed by 55ºC±2ºC - T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz - T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (a=0.05). Results: The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition. Conclusions: The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations. PMID:23559115

  14. Effect of surface pretreatment with two desensitizer techniques on the microleakage of resin composite restorations.

    PubMed

    Shafiei, Fereshteh; Memarpour, Mahtab

    2013-01-01

    This study evaluated the effect of two desensitizing procedures on the marginal microleakage of composite restorations bonded by a two-step etch-and-rinse adhesive. Class V cavities were prepared on the buccal surfaces of 42 extracted premolars at the cementoenamel junction and randomly divided into three groups of 14 each. In group 1 (control), an adhesive (Excite) was applied according to manufacturer's instructions. In group 2, after the application of oxalate desensitizer (BisBlock) to the cavities, the specimens were etched, and Excite was applied and light cured. In group 3, the cavities were treated with CO(2) laser irradiation (1 W power output in a continuous wave mode, 10 s), and then, the specimens were etched and bonded by Excite. All the cavities were restored with a resin composite. After water storage and thermocycling, the specimens were placed in 1 % basic fuchsin blue dye solution. The dye penetration was evaluated using a stereomicroscope. The data were analyzed by using Kruskal-Wallis and Mann-Whitney statistical tests (α = 0.05). There was a significant difference among three groups at the gingival and occlusal margins (P < 0.05). The specimens treated with BisBlock exhibited higher microleakage at both margins than those of the control and laser-treated groups (P < 0.001). There was no significant difference between the control group and group treated with CO(2) laser at both margins (P > 0.05). CO(2) laser did not show a detrimental effect on the marginal sealing ability of the adhesive system used in resin composite restorations. However, oxalate desensitizer adversely influenced the sealing ability of the restorations. PMID:22696076

  15. Cervical Interfacial Bonding Effectiveness of Class II Bulk Versus Incremental Fill Resin Composite Restorations.

    PubMed

    Al-Harbi, F; Kaisarly, D; Michna, A; ArRejaie, A; Bader, D; El Gezawi, M

    2015-01-01

    Cervical interfacial bonding quality has been a matter of deep concern. The purpose of this study was to analyze microtensile bond strength (MTBS) and cervical interfacial gap distance (IGD) of bulk-fill vs incremental-fill Class II composite restorations. Box-only Class II cavities were prepared in 91 maxillary premolars (n = 7) with gingival margin placement 1 mm above the cementoenamel junction at one side and 1 mm below it on the other side. Eighty-four maxillary premolars were divided into self-etch and total-etch groups and further subdivided into six restorative material subgroups used incrementally and with an open-sandwich technique: group 1, Tetric Ceram HB (TC) as a control; group 2, Tetric EvoFlow (EF); group 3, SDR Smart Dentin Replacement (SDR); group 4, SonicFill (SF); group 5, Tetric N-Ceram Bulk Fill (TN); and group 6, Tetric EvoCeram Bulk Fill (TE). Groups 2-6 were bulk-fill restoratives. Tetric N-Bond Self-Etch (se) and Tetric N-Bond total-etch (te) adhesive were used in subgroups 1-5, whereas AdheSE (se) and ExciTE F (te) were used in subgroup 6. In an additional group, Filtek P90 Low Shrink Restorative (P90) was used only with its corresponding self-etch bond. The materials were manipulated, light-cured (1600 mW/cm(2)), artificially aged (thermal and occlusal load-cycling), and sectioned. Two microrods/restoration (n = 14/group) were tested for MTBS at a crosshead-speed of 0.5 mm/min (Instron testing machine). Fracture loads were recorded (Newtons), and MTSBs were calculated (Megapascals). Means were statistically analyzed by the Kruskal-Wallis test, Conover-Inman post hoc analysis for MTBS (multiple comparisons), and Mann-Whitney U test for IGD. The ends of the fractures were examined for failure mode. One microrod/restoration (n = 7/group) was investigated by scanning electron microscopy (×1200) for IGD. MTBS values for SF/te, P90 in enamel, and TC+SDR/te in enamel and cementum were significantly higher compared with those for the control TC

  16. Evaluation of Microleakage of Dental Composites Using Bonding Agents with Different Placement Techniques: An Invitro Study

    PubMed Central

    Kaur, Jasvir; Garg, Deepanshu; Sunil, MK; Sawhney, Anshul; Malaviya, Neha; Tripathi, Shashank; Arora, Saloni

    2015-01-01

    Background The rapid progress of adhesive dentistry over the past decade has been attributed to the significant advances in dentin bonding technology. Requirements of an ideal bonding agent are quite similar to those indicated by Buonocore despite of many improvements. As we enter the new millennium, it is important for us to examine the past. Objective To evaluate the microleakage of three bonding agents namely Single Bond, Prime & Bond NT and Excite using different composite materials namely Z100, Spectrum TPH, Tetric with three different placement techniques. Materials and Methods Fifty four extracted human premolars were taken & divided into 9 groups depending upon application of bonding agents followed by composite restorations. Specimens were subjected to thermal cycling at 60C, 370C, 540C and again at 370C & then placed in 10 ml each of freshly prepared 50% silver nitrate solution for 2 hour in darkness, washed & placed under sun light for 24 hours. The sectioned specimens were then observed under stereomicroscope to detect microleakage. Results On comparing the mean microleakage scores among the three groups, maximum microleakage scores have been obtained when no bonding agent was used, while least microleakage scores were obtained with double coat of bonding agent. Conclusion The present study suggests that the placement of bonding agent technique before composite restoration can be effective to limit the microleakage at the tooth restoration interface. PMID:26501015

  17. Fracture Resistance of Premolars Restored by Various Types and Placement Techniques of Resin Composites

    PubMed Central

    Moosavi, Horieh; Zeynali, Mahsa; Pour, Zahra Hosseini

    2012-01-01

    To verify the fracture resistance of premolars with mesioocclusodistal preparations restored by different resin composites and placement techniques. Sixty premolars were randomly divided into two groups based on type of composite resin: Filtek P60 or Nulite F, and then each group was separated into three subgroups: bulk, centripetal, and fiber insert according to the type of placement method (n = 10). Single-bond adhesive system was used as composite bonding according to the manufacturer's instructions. Specimens were restored in Groups 1, 2, and 3 with Filtek P60 and in Groups 4, 5, and 6 with Nulite F. After being stored 24 hours at 37°C, a 4 mm diameter steel sphere in a universal testing machine was applied on tooth buccal and lingual cusps at a cross-head speed of 5 mm/min until fracture occurred. Groups 3 and 6 showed higher fracture resistance than Groups 1, 2, 4, and 5. Among the placement techniques, the fiber insert method had a significant effect, but the type of composite was ineffective. The insertion technique in contrast to the type of material had a significant influence on the fracture resistance of premolar teeth. PMID:22666255

  18. Effect of curing unit and adhesive system on marginal adaptation of composite restorations.

    PubMed

    Casselli, Denise Sa Maia; Faria-e-Silva, Andre Luis; Casselli, Henrique; Martins, Luis Roberto Marcondes

    2012-01-01

    This study sought to evaluate how a curing unit and adhesive system affected the marginal adaptation of resin composite restorations. Class V cavities were prepared in bovine teeth with a gingival margin in dentin and an incisal margin in enamel. The cavities were restored with a micro-hybrid resin composite using one of four adhesives: Single Bond 2, Prime & Bond NT, Clearfil SE Bond, Xeno IV. The light-activations were performed using a quartz-tungsten-halogen (QTH) lamp or a second-generation light-emitting diode (LED). Restorations were finished and polished and epoxy replicas were prepared. Marginal adaptation was analyzed by using scanning electronic microscopy (magnification 500X). The widest gaps in each margin were recorded, and data were submitted to Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests (α = 0.05). Differences between the adhesives were observed only when the dentin margins were evaluated: Clearfil SE Bond demonstrated better marginal adaptation than Prime & Bond NT or Single Bond 2 (which demonstrated the widest gaps in the dentin margin). The type of curing unit only affected the results for Xeno IV when the enamel margin was analyzed; the LED lamp promoted smaller gaps than the QTH lamp. PMID:23220321

  19. In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases and interface treatments. "Post-fatigue adaptation of indirect composite restorations".

    PubMed

    Rocca, Giovanni Tommaso; Gregor, Ladislav; Sandoval, Maria Jose; Krejci, Ivo; Dietschi, Didier

    2012-10-01

    The present study evaluated the influence of different composite bases and surface treatments on marginal and internal adaptation of class II indirect composite restorations, after simulated occlusal loading. Thirty-two class II inlay cavities were prepared on human third molars, with margins located in cementum. A 1-mm composite base extending up to the cervical margins was applied on all dentin surfaces in the experimental groups; impressions were made and composite inlays fabricated. The following experimental conditions were tested: no liner (control group), flowable composite treated with soft air abrasion (experiment 1), flowable composite sandblasted (experiment 2) and restorative composite sandblasted (experiment 3). All specimens were submitted to 1,000,000 cycles with a 100-N eccentric load. Tooth-restoration margins were analysed semi-quantitatively by scanning electron microscopy before and after loading; internal adaptation was also evaluated after test completion. The percentage of perfect adaptation in enamel was 79.5% to 92.7% before loading and 73.3% to 81.9% after loading. Perfect adaptation to dentin was reduced before loading (54.8% to 77.6%) and after loading (41.9% to 63%), but no difference was found among groups for pre- and post-loading conditions. No debonding occurred between the base and composite luting. A significant, negative influence of cyclic loading was observed. The results of the present study support the use of flowable or restorative composites as base/liner underneath large class II restorations. Soft air abrasion represents a potential alternative to airborne particle abrasion for treating cavities before cementation. The application of a composite base underneath indirect composite restorations represents a feasible non-invasive alternative to surgical crown lengthening to relocate cavity margins from an intra-crevicular to supra-gingival position. PMID:22065245

  20. Effect of prosthetic restoration on oral health-related quality of life in patients with shortened dental arches: a multicentre study.

    PubMed

    Fueki, K; Igarashi, Y; Maeda, Y; Baba, K; Koyano, K; Sasaki, K; Akagawa, Y; Kuboki, T; Kasugai, S; Garrett, N R

    2015-09-01

    The aim of this multicentre prospective study was to investigate the effect of prosthetic restoration for missing posterior teeth in patients with shortened dental arches (SDAs). SDA patients with 2-12 missing occlusal units (a pair of occluding premolars corresponds to one unit, and a pair of occluding molars corresponds to two units) were consecutively recruited from seven university-based dental hospitals in Japan. Patients chose no replacement of missing teeth or prosthetic treatment with removable partial dentures (RPDs) or implant-supported fixed partial dentures (IFPDs). Oral health-related quality of life (OHRQoL) was measured using the oral health impact profile (Japanese version - OHIP-J) at baseline and follow-up/post-treatment evaluation. Of the 169 subjects who completed baseline evaluation, 125 subjects (mean age; 63.0 years) received follow-up/post-treatment evaluation. No-treatment was chosen by 42% (53/125) of the subjects, and 58% (72/125) chose treatment with a RPD (n = 53) or an IFPD (n = 19). In the no-treatment (NT) group, the mean OHIP summary score at baseline was similar to that at follow-up evaluation (P = 0.69). In the treatment (TRT) group, the mean OHIP summary score decreased significantly after the RPD treatment (P = 0.002), and it tended to decrease, though not statistically significant (P = 0.18), after the IFPD treatment. The restoration of one occlusal unit was associated with a 1.2-point decrease in OHIP summary score (P = 0.034). These results suggest that the replacement of missing posterior teeth with RPDs or IFPDs improved OHRQoL. Prosthetic restoration for SDAs may benefit OHRQoL in patients needing replacement of missing posterior teeth. PMID:25818656

  1. Dental OCT

    NASA Astrophysics Data System (ADS)

    Wilder-Smith, Petra; Otis, Linda; Zhang, Jun; Chen, Zhongping

    This chapter describes the applications of OCT for imaging in vivo dental and oral tissue. The oral cavity is a diverse environment that includes oral mucosa, gingival tissues, teeth and their supporting structures. Because OCT can image both hard and soft tissues of the oral cavity at high resolution, it offers the unique capacity to identity dental disease before destructive changes have progressed. OCT images depict clinically important anatomical features such as the location of soft tissue attachments, morphological changes in gingival tissue, tooth decay, enamel thickness and decay, as well as the structural integrity of dental restorations. OCT imaging allows for earlier intervention than is possible with current diagnostic modalities.

  2. Microleakage in facial and lingual Class 5 composite restorations: a comparison.

    PubMed

    Barnes, D M; McDonald, N J; Thompson, V P; Blank, L W; Shires, P J

    1994-01-01

    The purpose of this in vitro study was to determine if there is a difference in microleakage between facial and lingual enamel and cementum using two different evaluation techniques. Class 5 preparations were made in 50 teeth on the facial and lingual tooth surfaces and restored using dentin bonding and composite resin. The teeth were thermocycled, silver nitrate stained, and longitudinally sectioned into mesial and distal halves through each restoration. The mesial half was scored using a rank order system. A Kruskal-Wallis one-way ANOVA was performed. The distal half was scored by measurement, and a two-sample t-test was performed. There were no statistically significant differences (P > or = 0.05) in microleakage between facial and lingual tooth enamel or cementum surfaces using either measurement technique. PMID:9028232

  3. Push-Out Bond Strength of Restorations with Bulk-Fill, Flow, and Conventional Resin Composites

    PubMed Central

    Caixeta, Rodrigo Vieira; Guiraldo, Ricardo Danil; Kaneshima, Edmilson Nobumitu; Barbosa, Aline Silvestre; Picolotto, Cassiana Pedrotti; Lima, Ana Eliza de Souza; Gonini Júnior, Alcides; Berger, Sandrine Bittencourt

    2015-01-01

    The aim of this study was to evaluate the bond strengths of composite restorations made with different filler amounts and resin composites that were photoactivated using a light-emitting diode (LED). Thirty bovine incisors were selected, and a conical cavity was prepared in the facial surface of each tooth. All preparations were etched with Scotchbond Etching Gel, the Adper Scotchbond Multipurpose Plus adhesive system was applied followed by photoactivation, and the cavities were filled with a single increment of Filtek Z350 XT, Filtek Z350 XT Flow, or bulk-fill X-tra fil resin composite (n = 10) followed by photoactivation. A push-out test to determine bond strength was conducted using a universal testing machine. Data (MPa) were submitted to Student's t-test at a 5% significance level. After the test, the fractured specimens were examined using an optical microscope under magnification (10x). Although all three composites demonstrated a high prevalence of adhesive failures, the bond strength values of the different resin composites photoactivated by LED showed that the X-tra fil resin composite had a lower bond strength than the Filtek Z350 XT and Filtek Z350 XT Flow resin composites. PMID:26457322

  4. Acceleration and novelty: community restoration speeds recovery and transforms species composition in Andean cloud forest.

    PubMed

    Wilson, Sarah Jane; Rhemtulla, Jeanine M

    2016-01-01

    Community-based tropical forest restoration projects, often promoted as a win-win solution for local communities and the environment, have increased dramatically in number in the past decade. Many such projects are underway in Andean cloud forests, which, given their extremely high biodiversity and history of extensive clearing, are understudied. This study investigates the efficacy of community-based tree-planting projects to accelerate cloud forest recovery, as compared to unassisted natural regeneration. This study takes place in northwest Andean Ecuador, where the majority of the original, highly diverse cloud forests have been cleared, in five communities that initiated tree-planting projects to restore forests in 2003. In 2011, we identified tree species along transects in planted forests (n = 5), naturally regenerating forests (n = 5), and primary forests (n = 5). We also surveyed 120 households about their restoration methods, tree preferences, and forest uses. We found that tree diversity was higher in planted than in unplanted secondary forest, but both were less diverse than primary forests. Ordination analysis showed that all three forests had distinct species compositions, although planted forests shared more species with primary forests than did unplanted forests. Planted forests also contained more animal-dispersed species in both the planted canopy and in the unplanted, regenerating understory than unplanted forests, and contained the highest proportion of species with use value for local people. While restoring forest increased biodiversity and accelerated forest recovery, restored forests may also represent novel ecosystems that are distinct from the region's previous ecosystems and, given their usefulness to people, are likely to be more common in the future. PMID:27039520

  5. Diagnostic value of DIAGNOdent in detecting caries under composite restorations of primary molars

    PubMed Central

    Sichani, Ava Vali; Javadinejad, Shahrzad; Ghafari, Roshanak

    2016-01-01

    Background: Direct observation cannot detect caries under restorations; therefore, the aim of this study was to compare the accuracy of radiographs and DIAGNOdent in detecting caries under restorations in primary teeth using histologic evaluation. Materials and Methods: A total of 74 previously extracted primary molars (37 with occlusal caries and 37 without caries) were used. Class 1 cavity preparations were made on each tooth by a single clinician and then the preparations were filled with composite resin. The accuracy of radiographs and DIAGNOdent in detecting caries was compared using histologic evaluation. The data were analyzed by SPSS version 21 using Chi-square, Mc Namara statistical tests and receiver operating characteristic curve. The significance was set at 0.05. Results: The sensitivity and specificity for DIAGNOdent were 70.97 and 83.72, respectively. Few false negative results were observed, and the positive predictive value was high (+PV = 75.9) and the area under curve was more than 0.70 therefore making DIAGNOdenta great method for detecting caries (P = 0.0001). Two observers evaluated the radiographs and both observers had low sensitivity ( first observer: 48.39) (second observer: 51.61) and high specificity (both observers: 79.07). The +PV was lower than DIAGNOdent and the area under curve for both observers was less than 0.70. However, the difference between the two methods was not significant. Conclusion: DIAGNOdent showed a greater accuracy in detecting secondary caries under primary molar restorations, compared to radiographs. Although DIAGNOdent is an effective method for detecting caries under composite restorations, it is better to be used as an adjunctive method alongside other detecting procedures. PMID:27605990

  6. Effect of alcoholic beverages on surface roughness and microhardness of dental composites.

    PubMed

    DA Silva, Marcos Aurélio Bomfim; Vitti, Rafael Pino; Sinhoreti, Mário Alexandre Coelho; Consani, Rafael Leonardo Xediek; Silva-Júnior, José Ginaldo da; Tonholo, Josealdo

    2016-01-01

    The aim of this study was to evaluate the microhardness and surface roughness of composite resins immersed in alcoholic beverages. Three composite resins were used: Durafill (Heraeus Kulzer), Z250 (3M-ESPE) and Z350 XT (3M-ESPE). The inital surface roughness and microhardness were measured. The samples were divided into four groups (n=30): G1-artificial saliva; G2-beer; G3-vodka; G4-whisky. The samples were immersed in the beverages 3× a day for 15 min and 30 days. The surface roughness and microhardness assays were repeated after immersion period. The data were statistically analyzed by two-way ANOVA and Tukey-HSD test (p<0.05). Surface roughness increased for all composite resins immersed in beer and whisky. Microhardness of all groups decreased after immersion in alcoholic beverages. The effect of these beverages on dental composites is depended upon the chemical composition, immersion time, alcohol content and pH of solutions. PMID:27477228

  7. Selective removal of dental composite with a diode-pumped Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Fried, William A.; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel

    2016-02-01

    Selective removal of dental composite with high precision is best accomplished using lasers operating at high pulse repetition rates focused to a small spot size. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to compare the ablation rates and selectivity of enamel and composite for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 30-50-μs and evaluate it's suitability for the selective removal of composite from tooth surfaces. The depth of ablation and changes in surface morphology were assessed using digital microscopy. The fluence range of 30-50 J/cm2 appeared optimal for the removal of composite, and damage to sound enamel was limited to less than 100-μm after the removal of composite as thick as 700-800-μm. Future studies will focus on the use of methods of feedback to further increase selectivity.

  8. Selective removal of dental composite with a diode-pumped Er:YAG laser

    PubMed Central

    Fried, William A.; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel

    2016-01-01

    Selective removal of dental composite with high precision is best accomplished using lasers operating at high pulse repetition rates focused to a small spot size. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to compare the ablation rates and selectivity of enamel and composite for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 30–50-μs and evaluate it’s suitability for the selective removal of composite from tooth surfaces. The depth of ablation and changes in surface morphology were assessed using digital microscopy. The fluence range of 30–50 J/cm2 appeared optimal for the removal of composite, and damage to sound enamel was limited to less than 100-μm after the removal of composite as thick as 700–800-μm. Future studies will focus on the use of methods of feedback to further increase selectivity. PMID:26997741

  9. Marginal adaptation of class II resin composite restorations using incremental and bulk placement techniques: an ESEM study.

    PubMed

    Idriss, S; Habib, C; Abduljabbar, T; Omar, R

    2003-10-01

    This in vitro study compared marginal gap formation in class II resin composite restorations. Forty caries-free extracted molars were prepared in a standardized manner for class II restoration by one of four methods: bulk- or incrementally-placed light-activated resin composite (Amelogen), and bulk- or incrementally-placed chemically activated composite (Rapidfill). The restored teeth, after finishing and polishing, and thermocycling, were examined using environmental scanning electron microscopy. Marginal gap measurements at predetermined facial and lingual margin sites showed no significant differences between the two sites within any of the groups. Both the light- and the chemically-activated restorations showed no significant differences in mean marginal gap sizes whether they were placed by incremental or bulk techniques. Amelogen restorations placed by both methods had significantly larger margin gaps than those of each of the Rapidfill groups (P<0.05). Thus, although method of placement of a given material had no significant effect on the quality of marginal adaptation, both of the chemically activated resin composite restorations produced significantly smaller marginal gaps than both the bulk- and incrementally-placed light-activated composites. PMID:12974860

  10. Fracture Load of Tooth Restored with Fiber Post and Experimental Short Fiber Composite

    PubMed Central

    Bijelic, Jasmina; Garoushi, Sufyan; Vallittu, Pekka K; Lassila, Lippo V.J

    2011-01-01

    Purpose: This study evaluated the load bearing capacity of anatomically designed canines restored with FRC posts and experimental short fiber composite resin (FC). The effect of using three different types of tooth preparation and woven net on the fracture load was also investigated. Further aim was to evaluate the failure mode of each restoration. Material and methods: 80 maxillary frasaco-canines were divided into 10 groups (n=8). The anatomic crowns were cut perpendicular at CEJ of the tooth. Group 1 was composed of teeth with flattened surface. Groups 2, 3 & 4 were prepared of teeth with 2 mm ferrule. In the third group, everStick Net was applied above the ferrule. Group 5 was composed of teeth with large box type preparation. The root canals were enlarged, sandblasted and then surface treated with Stick resin for 5 min. Two types of FRC root canal posts were used. The crowns were prepared either with composite resin or with FC. A static load until failure was applied to the crowns at a 45 degrees angle. Failure modes were visually examined. Results: ANOVA revealed that use of FRC-post and tooth preparation (p<0.001) had significant effect on fracture load of FRC-crown. The crowns made from only FC gave comparable fracture load to groups with FRC-post. No significant difference was found in load-bearing capacity between restorations reinforced with FRC net-substructure and those without (p>0.001). Chi-square test revealed that both, crown design and existence of FRC-post effected significantly fracture types (p<0.001). Conclusion: FC demonstrated similar load bearing capacity with restorations reinforced with FRC post. The presence of ferrule around the tooth increased the load bearing capacity significantly. Abbreviations: EET – endodontically treated teeth; FRC – fiber-reinforced composite; semi-IPN – semi-interpenetrating network; CEJ – cementoenamel junction; FC – experimental short fiber composite; SiC – silicon carbide abrasive paper; N

  11. The significance of cone beam computed tomography for the visualization of anatomical variations and lesions in the maxillary sinus for patients hoping to have dental implant-supported maxillary restorations in a private dental office in Japan

    PubMed Central

    2014-01-01

    Objectives The purpose of the present study was to elucidate the significance of cone bean computed tomography (CBCT) for patients hoping to undergo implant-supported restorations of the maxilla. Therefore, two studies were planned. One was to compare the prevalence of anatomic variations and lesions in the maxillary sinus on CBCT of patients hoping to undergo implant-supported restorations of the maxilla with that in patients with other chief complaints in a private dental office in Japan. The other study was to elucidate the limitations of panoramic radiographs in the detection of anatomic variations and lesions in the maxillary sinus. Study design Sixty-one pairs of panoramic radiographs and CBCT were retrospectively analyzed in two groups of patients, those who hoped to undergo implant-supported restorations in the maxilla (Implant group) and those who did not (Non-implant group). The presence of anatomic variations and lesions in the maxillary sinus were analyzed. Results The detection rate of mucosal thickening was significantly higher in the Implant group than in the Non-implant group. The detection rates for the features analyzed were significantly lower on panoramic radiographs. In particular, the detection rates of internal and anterior locations of some features were noticeably lower on panoramic radiographs. A significant relationship was found between the change in the detection rate on panoramic radiographs and the widths of mucosal thickening or the lengths of the major axis of SOLs in the maxillary sinus. If the width of mucosal thickening or the length of the major axis of SOLs was <3 mm or <4 mm, respectively, the detection rate on panoramic radiographs was significantly decreased. Conclusion CBCT is important for patients hoping to undergo implant-supported restorations of the maxilla because of the mucosal thickening in the maxillary sinus in such patients and their lower detection rates on panoramic radiographs. PMID:24884983

  12. Bacterial Viability and Physical Properties of Antibacterially Modified Experimental Dental Resin Composites

    PubMed Central

    Rüttermann, Stefan; Trellenkamp, Taina; Bergmann, Nora; Beikler, Thomas; Ritter, Helmut; Janda, Ralf

    2013-01-01

    Purpose To investigate the antibacterial effect and the effect on the material properties of a novel delivery system with Irgasan as active agent and methacrylated polymerizable Irgasan when added to experimental dental resin composites. Materials and Methods A delivery system based on novel polymeric hollow beads, loaded with Irgasan and methacrylated polymerizable Irgasan as active agents were used to manufacture three commonly formulated experimental resin composites. The non-modified resin was used as standard (ST). Material A contained the delivery system providing 4 % (m/m) Irgasan, material B contained 4 % (m/m) methacrylated Irgasan and material C 8 % (m/m) methacrylated Irgasan. Flexural strength (FS), flexural modulus (FM), water sorption (WS), solubility (SL), surface roughness Ra, polymerization shrinkage, contact angle Θ, total surface free energy γS and its apolar γSLW, polar γSAB, Lewis acid γS+and base γS- term as well as bacterial viability were determined. Significance was p < 0.05. Results The materials A to C were not unacceptably influenced by the modifications and achieved the minimum values for FS, WS and SL as requested by EN ISO 4049 and did not differ from ST what was also found for Ra. Only A had lower FM than ST. Θ of A and C was higher and γSAB of A and B was lower than of ST. Materials A to C had higher γS+ than ST. The antibacterial effect of materials A to C was significantly increased when compared with ST meaning that significantly less vital cells were found. Conclusion Dental resin composites with small quantities of a novel antibacterially doped delivery system or with an antibacterial monomer provided acceptable physical properties and good antibacterial effectiveness. The sorption material being part of the delivery system can be used as a vehicle for any other active agent. PMID:24223890

  13. A randomized double-blind clinical trial of posterior composite restorations with or without bevel: 1-year follow-up

    PubMed Central

    COELHO-DE-SOUZA, Fábio Herrmann; CAMARGO, Junara Cristina; BESKOW, Tiago; BALESTRIN, Matheus Dalmolin; KLEIN-JÚNIOR, Celso Afonso; DEMARCO, Flávio Fernando

    2012-01-01

    Objective This randomized double-blind clinical trial compared the performance of posterior composite restorations with or without bevel, after 1-year follow-up. Material and Methods Thirteen volunteers requiring at least two posterior composite restorations were selected. Twenty-nine cavities were performed, comprising 14 without bevel (butt joint) and 15 with bevel preparation of the enamel cavosurface angle. All cavities were restored with simplified adhesive system (Adper Single Bond) and composite resin (Filtek P60). A halogen light curing unit was used through the study. Restorations were polished immediately. Analysis was carried out at baseline, after 6 months and after 1 year by a calibrated evaluator (Kappa), according to the FDI criteria. Data were statistically analyzed by Mann-Whitney test (p<0.05). Results Beveled and non-beveled cavities performed similarly after 1 year follow-up, regarding to fractures and retention, marginal adaptation, postoperative hypersensitivity, recurrence of caries, surface luster and anatomic form. However, for surface and marginal staining, beveled cavities showed significantly better performance (p<0.05) than butt joint restorations. Conclusions It was concluded that the restorations were acceptable after 1 year, but restorations placed in cavities with marginal beveling showed less marginal staining than those placed in non-beveled cavities. PMID:22666833

  14. Compressive strength of dental composites photo-activated with different light tips

    NASA Astrophysics Data System (ADS)

    Galvão, M. R.; Caldas, S. G. F. R.; Calabrez-Filho, S.; Campos, E. A.; Bagnato, V. S.; Rastelli, A. N. S.; Andrade, M. F.

    2013-04-01

    The aim of this study was to evaluate the compressive strength of microhybrid (Filtek™ Z250) and nanofilled (Filtek™ Supreme XT) composite resins photo-activated with two different light guide tips, fiber optic and polymer, coupled with one LED. The power density was 653 mW cm-2 when using the fiber optic light tip and 596 mW cm-2 with the polymer. After storage in distilled water at 37 ± 2 °C for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5 mm min-1. The statistical analysis was performed using ANOVA with a confidence interval of 95% and Tamhane’s test. The results showed that the mean values of compressive strength were not influenced by the different light tips (p > 0.05). However, a statistical difference was observed (p < 0.001) between the microhybrid composite resin photo-activated with the fiber optic light tip and the nanofilled composite resin. Based on these results, it can be concluded that microhybrid composite resin photo-activated with the fiber optic light tip showed better results than nanofilled, regardless of the tip used, and the type of the light tip did not influence the compressive strength of either composite. Thus, the presented results suggest that both the fiber optic and polymer light guide tips provide adequate compressive strength to be used to make restorations. However, the fiber optic light tip associated with microhybrid composite resin may be an interesting option for restorations mainly in posterior teeth.

  15. Evaluation of polymerization shrinkage of dental composites by an optical method.

    PubMed

    Weig, K M; Magalhães Filho, T R; Costa Neto, C A; Costa, M F

    2015-02-01

    This study proposes an alternative methodology for evaluating polymerization shrinkage of dental composites using an advanced video extensometer (AVE) system. This equipment measures the displacement between two points drawn on a tooth's wall without requiring physical contact with the tooth. By doing so, the polymerization process was monitored by the cusp deflection. This technique was used in human and bovine teeth, where the cavities were prepared under controlled conditions so that the volume of the composite used was the same in both types of teeth. After the cavity preparation, the specimens were acid etched, washed and dried, and then the adhesive was applied and polymerized. The composite was then inserted into the cavity. Polymerization was performed with two different light polymerizing units (LD Max and Optilight Max - Gnatus do Brasil), and the displacement curve of the tooth cusp was recorded for a period of 400 s. After a statistical analysis, it was concluded that the technique was capable of evaluating shrinkage by the deflection from the cusps and that the human and bovine teeth do not react in a similar manner towards the polymerization shrinkage of composites. PMID:25492174

  16. An alumina toughened zirconia composite for dental implant application: in vivo animal results.

    PubMed

    Schierano, Gianmario; Mussano, Federico; Faga, Maria Giulia; Menicucci, Giulio; Manzella, Carlo; Sabione, Cristian; Genova, Tullio; von Degerfeld, Mitzy Mauthe; Peirone, Bruno; Cassenti, Adele; Cassoni, Paola; Carossa, Stefano

    2015-01-01

    Ceramic materials are widely used for biomedical applications because of their remarkable biological and mechanical properties. Composites made of alumina and zirconia are particularly interesting owing to their higher toughness with respect to the monolithic materials. On this basis, the present study is focused on the in vivo behavior of alumina toughened zirconia (ATZ) dental implants treated with a hydrothermal process. A minipig model was implemented to assess the bone healing through histology and mRNA expression at different time points (8, 14, 28, and 56 days). The novel ATZ implant was compared to a titanium clinical standard. The implants were analyzed in terms of microstructure and surface roughness before in vivo tests. The most interesting result deals with a statistically significant higher digital histology index for ATZ implants with respect to titanium standard at 56 days, which is an unprecedented finding, to the authors' knowledge. Even if further investigations are needed before proposing the clinical use in humans, the tested material proved to be a promising candidate among the possible ceramic dental implants. PMID:25945324

  17. An Alumina Toughened Zirconia Composite for Dental Implant Application: In Vivo Animal Results

    PubMed Central

    Schierano, Gianmario; Faga, Maria Giulia; Menicucci, Giulio; Sabione, Cristian; Genova, Tullio; von Degerfeld, Mitzy Mauthe; Peirone, Bruno; Cassenti, Adele; Cassoni, Paola; Carossa, Stefano

    2015-01-01

    Ceramic materials are widely used for biomedical applications because of their remarkable biological and mechanical properties. Composites made of alumina and zirconia are particularly interesting owing to their higher toughness with respect to the monolithic materials. On this basis, the present study is focused on the in vivo behavior of alumina toughened zirconia (ATZ) dental implants treated with a hydrothermal process. A minipig model was implemented to assess the bone healing through histology and mRNA expression at different time points (8, 14, 28, and 56 days). The novel ATZ implant was compared to a titanium clinical standard. The implants were analyzed in terms of microstructure and surface roughness before in vivo tests. The most interesting result deals with a statistically significant higher digital histology index for ATZ implants with respect to titanium standard at 56 days, which is an unprecedented finding, to the authors' knowledge. Even if further investigations are needed before proposing the clinical use in humans, the tested material proved to be a promising candidate among the possible ceramic dental implants. PMID:25945324

  18. Effect of In-Office Bleaching on Color and Surface Roughness of Composite Restoratives

    PubMed Central

    Hafez, Randa; Ahmed, Doa; Yousry, Mai; El-Badrawy, Wafa; El-Mowafy, Omar

    2010-01-01

    Objectives: The purpose of this study was to determine color changes and surface roughness of composites when they were subjected to in-office bleaching. Methods: 12 discs 15 mm in diameter and 2 mm thick were prepared from two shades (A2 & A4) of two composites, Durafil VS (DF) and TPH3 (TPH). Specimens were polished and stored in distilled water for 24 hours at 37°C before being subjected to bleaching, staining, and re-bleaching. Each of the groups of specimens (DF-A2, DF-A4, TPH-A2 and TPH-A4) were subdivided into three subgroups (n=4) and bleached with Beyond, LumaWhite-Plus, and Opalescence-Boost. Specimens were then stained by immersing them in a coffee solution for 48 hours at 37°C, and then they were re-bleached. Colorimetric measurements were performed at baseline, after bleaching, after staining, and after re-bleaching. Surface roughness was determined with environmental SEM before and after bleaching. Data were statistically-analyzed. Results: None of the bleaching systems notably changed the color of composites (delta-E<2). Coffee staining affected DF specimens more than TPH. Stained specimens showed variable responses to whitening with no significant color change observed with TPH (delta-E<2) and significant changes observed with DF. Surface roughness significantly changed with bleaching, but the degree varied according to composite shade and bleaching agent. Conclusions: Three in-office bleaching agents had no significant color changes on two composites. DF showed more color change than TPH when immersed in coffee. Stained composites showed different degrees of whitening, with DF showing more response. Bleaching may adversely affect the surface texture of composites. Dentists should take into consideration that composite restorations may not respond to bleaching in the same way that natural teeth do. PMID:20396441

  19. Nanoleakage Evaluation of Posterior Teeth Restored with Low Shrinkable Resin Composite- An invitro Study

    PubMed Central

    Labib, Labib Mohamed; Nabih, Sameh Mahmoud

    2016-01-01

    Introduction The effect of nanoleakage on the integrity of resin–dentin bond has been in interest for long-term adhesion. Aim This study evaluated the nanoleakage in premolar teeth restored with low shrinkable resin composite. Materials and Methods A total of 40 human premolars were used for nanoleakage evaluation in this study. Each group was divided into four equal groups; Group A: using silorane with its adhesive system. Group B: using silorane with G-bond. Group C: using Filtek supreme composite with G-bond. Group D: using Filtek supreme composite with AdheSE adhesive. Nanoleakage analysed using Scaning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectrometery (EDX). Results The amount of silver present in hybrid layer depend on the adhesive used; this indicated different nanoleakage expressions in different adhesive systems. Filtek Z350 composite with G-bond showed clear silver uptake in both the adhesive and hybrid layer. Low shrinkable resin composite (silorane) with its adhesive system showed less silver penetration and slight silver peak on the elemental energy spectroscopy of energy dispersive X-Ray spectrometry (EDS) as compared to other samples. Conclusion Adhesives used between different groups, influence the location and degree of nanoleakage. There is difference in nanoleakage patterns between two-step and one-step adhesives and also among the one-step adhesives themselves.

  20. Extractable nitrogen and microbial community structure respond to grassland restoration regardless of historical context and soil composition

    PubMed Central

    Dickens, Sara Jo M.; Allen, Edith B.; Santiago, Louis S.; Crowley, David

    2015-01-01

    Grasslands have a long history of invasion by exotic annuals, which may alter microbial communities and nutrient cycling through changes in litter quality and biomass turnover rates. We compared plant community composition, soil chemical and microbial community composition, potential soil respiration and nitrogen (N) turnover rates between invaded and restored plots in inland and coastal grasslands. Restoration increased microbial biomass and fungal : bacterial (F : B) ratios, but sampling season had a greater influence on the F : B ratio than did restoration. Microbial community composition assessed by phospholipid fatty acid was altered by restoration, but also varied by season and by site. Total soil carbon (C) and N and potential soil respiration did not differ between treatments, but N mineralization decreased while extractable nitrate and nitrification and N immobilization rate increased in restored compared with unrestored sites. The differences in soil chemistry and microbial community composition between unrestored and restored sites indicate that these soils are responsive, and therefore not resistant to feedbacks caused by changes in vegetation type. The resilience, or recovery, of these soils is difficult to assess in the absence of uninvaded control grasslands. However, the rapid changes in microbial and N cycling characteristics following removal of invasives in both grassland sites suggest that the soils are resilient to invasion. The lack of change in total C and N pools may provide a buffer that promotes resilience of labile pools and microbial community structure. PMID:25555522

  1. Three-year randomised clinical trial to evaluate the clinical performance, quantitative and qualitative wear patterns of hybrid composite restorations

    PubMed Central

    Palaniappan, Senthamaraiselvi; Elsen, Liesbeth; Lijnen, Inge; Peumans, Marleen; Van Meerbeek, Bart

    2009-01-01

    The aim of the study was to compare the clinical performance, quantitative and qualitative wear patterns of conventional hybrid (Tetric Ceram), micro-filled hybrid (Gradia Direct Posterior) and nano-hybrid (Tetric EvoCeram, TEC) posterior composite restorations in a 3-year randomised clinical trial. Sixteen Tetric Ceram, 17 TEC and 16 Gradia Direct Posterior restorations were placed in human molars and evaluated at baseline, 6, 12, 24 and 36 months of clinical service according to US Public Health Service criteria. The gypsum replicas at each recall were used for 3D laser scanning to quantify wear, and the epoxy resin replicas were observed under scanning electron microscope to study the qualitative wear patterns. After 3 years of clinical service, the three hybrid restorative materials performed clinically well in posterior cavities. Within the observation period, the nano-hybrid and micro-hybrid restorations evolved better in polishability with improved surface gloss retention than the conventional hybrid counterpart. The three hybrid composites showed enamel-like vertical wear and cavity-size dependant volume loss magnitude. Qualitatively, while the micro-filled and nano-hybrid composite restorations exhibited signs of fatigue similar to the conventional hybrid composite restorations at heavy occlusal contact area, their light occlusal contact areas showed less surface pitting after 3 years of clinical service. PMID:19669176

  2. Extractable nitrogen and microbial community structure respond to grassland restoration regardless of historical context and soil composition.

    PubMed

    Dickens, Sara Jo M; Allen, Edith B; Santiago, Louis S; Crowley, David

    2015-01-01

    Grasslands have a long history of invasion by exotic annuals, which may alter microbial communities and nutrient cycling through changes in litter quality and biomass turnover rates. We compared plant community composition, soil chemical and microbial community composition, potential soil respiration and nitrogen (N) turnover rates between invaded and restored plots in inland and coastal grasslands. Restoration increased microbial biomass and fungal : bacterial (F : B) ratios, but sampling season had a greater influence on the F : B ratio than did restoration. Microbial community composition assessed by phospholipid fatty acid was altered by restoration, but also varied by season and by site. Total soil carbon (C) and N and potential soil respiration did not differ between treatments, but N mineralization decreased while extractable nitrate and nitrification and N immobilization rate increased in restored compared with unrestored sites. The differences in soil chemistry and microbial community composition between unrestored and restored sites indicate that these soils are responsive, and therefore not resistant to feedbacks caused by changes in vegetation type. The resilience, or recovery, of these soils is difficult to assess in the absence of uninvaded control grasslands. However, the rapid changes in microbial and N cycling characteristics following removal of invasives in both grassland sites suggest that the soils are resilient to invasion. The lack of change in total C and N pools may provide a buffer that promotes resilience of labile pools and microbial community structure. PMID:25555522

  3. Modulated photoactivation of composite restoration: measurement of cuspal movement using holographic interferometry.

    PubMed

    Blažić, Larisa; Pantelić, Dejan; Savić-Šević, Svetlana; Murić, Branka; Belić, Ilija; Panić, Bratimir

    2011-03-01

    The purpose of this research was to investigate the influence of modulated photoactivation on cuspal movement. Eight class II MOD composite restorations were analyzed under various photoactivation protocols in a real-time manner using holographic interferometry. During the first photoactivation protocol, the composite restoration was illuminated for 200 s continuously. In the second protocol, the polymerization lamp was first turned on for 5 s, then turned off for 120 s, and again turned on for a final 195 s. In both protocols, radiant exposure was the same. A significant decrease (p < 0.05) in cuspal deflection was found for two-step irradiation (average value of total cuspal deflection was 5.03 ± 0.62 µm) compared to continuous irradiation (average value of total cuspal deflection was 5.95 ± 0.65 µm). The two-step photoactivation protocol was found preferable, since it resulted in a significantly lower cuspal deflection (11% lower, compared to the continuous illumination). PMID:20309595

  4. Composite resin in medicine and dentistry.

    PubMed

    Stein, Pamela S; Sullivan, Jennifer; Haubenreich, James E; Osborne, Paul B

    2005-01-01

    Composite resin has been used for nearly 50 years as a restorative material in dentistry. Use of this material has recently increased as a result of consumer demands for esthetic restorations, coupled with the public's concern with mercury-containing dental amalgam. Composite is now used in over 95% of all anterior teeth direct restorations and in 50% of all posterior teeth direct restorations. Carbon fiber reinforced composites have been developed for use as dental implants. In medicine, fiber-reinforced composites have been used in orthopedics as implants, osseous screws, and bearing surfaces. In addition, hydroxyapatite composite resin has become a promising alternative to acrylic cement in stabilizing fractures and cancellous screw fixation in elderly and osteoporotic patients. The use of composite resin in dentistry and medicine will be the focus of this review, with particular attention paid to its physical properties, chemical composition, clinical applications, and biocompatibility. PMID:16393132

  5. Pulsed laser-induced micro-and nanosized morphology and composition of titanium dental implants

    NASA Astrophysics Data System (ADS)

    Joób-Fancsaly, Á.; Divinyi, T.; Fazekas, Á.; Daroczi, Cs; Karacs, A.; Petõ, G.

    2002-10-01

    The surface morphology of machined screw-shaped titanium dental implants was modified by pulsed irradiation with an Nd glass laser. This method supplied very different surface elements in nanometer and micrometer ranges identified with scanning electron microscopy and atomic force microscopy as well. The surface composition was unchanged during these treatments. A rabbit experiment was carried out to investigate the direct bone contact (osseointegration) which was characterized by the removal torque of the implants. The 50 nm and 10-50 µm sized droplike elements were formed from the machined flat surface by the laser irradiation depending on the laser intensity. The osseointegration was enhanced by the increase of the density of nanosized elements and by the size of the microsized elements, showing the importance of this surface morphology in the direct bone-implant contact.

  6. Computed-tomography scan-based finite element analysis of stress distribution in premolars restored with composite resin

    NASA Astrophysics Data System (ADS)

    Kantardžić, I.; Vasiljević, D.; Blažić, L.; Puškar, T.; Tasić, M.

    2012-05-01

    Mechanical properties of restorative material have an effect on stress distribution in the tooth structure and the restorative material during mastication. The aim of this study was to investigate the influence of restorative materials with different moduli of elasticity on stress distribution in the three-dimensional (3D) solid tooth model. Computed tomography scan data of human maxillary second premolars were used for 3D solid model generation. Four composite resins with a modulus of elasticity of 6700, 9500, 14 100 and 21 000 MPa were considered to simulate four different clinical direct restoration types. Each model was subjected to a resulting force of 200 N directed to the occlusal surface, and stress distribution and maximal von Mises stresses were calculated using finite-element analysis. We found that the von Mises stress values and stress distribution in tooth structures did not vary considerably with changing the modulus of elasticity of restorative material.

  7. Principles of restorative dentistry.

    PubMed

    Banker, T

    1993-08-01

    A great deal of information regarding materials, instrumentation, and techniques used for restorative dentistry can be borrowed from the human dental field. Veterinary restorative dentistry is in its infancy. A thorough knowledge of the commonly used materials and how they can be effectively applied is important. Treatment planning is probably one of the most critical phases of restorative dentistry as is painstaking attention to detail. If the guidelines for restorative dental techniques are followed, failures will be minimal. However, one of the most important points to remember is that the success of a restoration is not determined at the completion of the procedure. A restoration, if properly planned and performed, should last the lifetime of the animal patient. It is very important that veterinary dentists continue to evaluate and assess their restorative work at regular intervals so that restorative failures can be detected early, and so that restorative techniques and materials can be critically evaluated in veterinary patients. PMID:8210800

  8. Effects of resin luting agents and 1% NaOCl on the marginal fit of indirect composite restorations in primary teeth

    PubMed Central

    BORGES, Ana Flávia Sanches; SIMONATO, Luciana Estevam; PASCON, Fernanda Miori; KANTOWITZ, Kamila Rosamiglia; RONTANI, Regina Maria Puppin

    2011-01-01

    Objective The purpose of this study was to provide information regarding the marginal adaptation of composite resin onlays in primary teeth previously treated with 1% sodium hypochlorite (NaOCl) (pulp irrigant) using two different resin luting agents. Material and Methods Forty extracted sound primary molars had their crowns prepared in a standardized machine and were randomly divided into 4 groups (n=10): G1 (1% NaOCl irrigation+EnForce); G2 (EnForce); G3 (1% NaOCl irrigation+Rely X); G4 (Rely X). The onlays were made with Z250 composite resin on plaster models. After luting, the tooth/restoration set was stored in 100% relative humidity at 37ºC for 24 h and finished with Soflex discs. Caries Detector solution was applied at the tooth/restoration interface for 5 s. The specimens were washed and four digital photos of each tooth were then taken. The extents of the gaps were measured with Image Tool 3.0 software. The percentage data were submitted to a Kruskal-Wallis test (α=0.05). The Relative Risk test analyzed the chance of a gap presence correlated to each group. Results There were no statistically significant differences (p>0.05) among the groups. The relative risk test revealed that some groups were more apt to have a presence of gaps than others. Conclusion Neither the 1% NaOCl treatment nor the resin luting agents caused any alterations in the dental substrate that could have influenced the marginal adaptation of composite onlays in primary teeth. PMID:21986649

  9. The Use of Quaternary Ammonium to Combat Dental Caries

    PubMed Central

    Ge, Yang; Wang, Suping; Zhou, Xuedong; Wang, Haohao; Xu, Hockin H. K.; Cheng, Lei

    2015-01-01

    Resin composites and adhesives are increasingly popular in dental restorations, but secondary caries is one of the main reasons for restoration failure. Quaternary ammonium monomers (QAMs) have an anti-microbial effect and are widely used in many fields. Since the concept of the immobilized antibacterial effect was put forward, dental restorations containing QAMs have been studied to reduce secondary caries. Previous studies have been struggling to develop novel anti-caries materials which might have triple benefits: good mechanical properties, antibacterial effects and remineralization potentials. Different kinds of QAMs have been proven to be effective in inhibiting the growth and metabolism of biofilms. Combination of QAMs and other nanoparticles in resin composites and adhesives could enhance their anti-caries capability. Therefore, QAMs are promising to show significant impact on the future of restorative and preventive dentistry. PMID:26635932

  10. Antimicrobial Susceptibility and Composition of Microcosm Dental Plaques Supplemented with Sucrose

    PubMed Central

    Pratten, J.; Wilson, M.

    1999-01-01

    The aims of this study were to evaluate the effects of repeated chlorhexidine gluconate (CHG) pulsing on the viability and bacterial composition of microcosm dental plaques derived from human saliva. The biofilms were grown on bovine enamel discs in a constant-depth film fermentor fed with an artificial saliva which was supplemented thrice daily with sucrose. The microcosm plaques had total viable anaerobic counts of 5 × 108 CFU per mm2 and consisted of 12% Actinomyces spp., 85% streptococci, and 0.2% Veillonella spp. When pulsed twice daily with 0.2% CHG, there was an immediate 1.3-log10 reduction in the total viable (anaerobic) count. However, as pulsing continued, the viable counts recovered, and after 4 days, the anaerobic count reached its pre-CHG-pulsing level, although the bacterial composition of the biofilms had changed. The results of this study show that twice-daily pulsing with 0.2% CHG over a 4-day period was ineffective at reducing the total anaerobic viable count of the biofilms but did alter their bacterial composition. PMID:10390209

  11. Effect of the Purple Corn Beverage “Chicha Morada” in Composite Resin during Dental Bleaching

    PubMed Central

    Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio

    2016-01-01

    During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3). PMID:27034897

  12. Effect of the Purple Corn Beverage "Chicha Morada" in Composite Resin during Dental Bleaching.

    PubMed

    Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio; Tay, Lidia Yileng

    2016-01-01

    During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3). PMID:27034897

  13. Effect of hydroxyapatite whisker surface graft polymerization on water sorption, solubility and bioactivity of the dental resin composite.

    PubMed

    Liu, Fengwei; Jiang, Xiaoze; Bao, Shuang; Wang, Ruili; Sun, Bin; Zhu, Meifang

    2015-08-01

    The aim of this study was to investigate the effect of poly bisphenol A glycidyl methacrylate (poly(Bis-GMA)) grafted hydroxyapatite whisker (PGHW) on water sorption, solubility and bioactivity of the dental resin composite. PGHW with different graft ratios was synthesized, by controlling grafting time, and filled into a dental resin matrix respectively. Fracture surface of the resin composites showed that PGHW-matrix interfacial compatibility and bonding were enhanced, and lower amounts of poly(Bis-GMA) on PGHW-1h (graft ratio: 8.5 wt.%) could facilitate the dispersion of PGHW-1 h in the composite. The PGHW-1h filled resin composite absorbed the lowest amount of water (27.16 μg/mm(3), 7 d), whereas the untreated hydroxyapatite whisker (HW) filled resin composite absorbed the highest. PGHW with higher graft ratios induced the decrease of the monomer conversion in the resulting composite, therefore, the PGHW-18 h (graft ratio: 32.8 wt.%) filled resin composite had the highest solubility. In vitro bioactivity of the studied resin composites in simulated body fluid (SBF) showed that a dense and continuous apatite layer was formed on the surface of the resin composite, and the surface graft polymerization on the whisker did not significantly affect the apatite forming ability of the resin composite. It was revealed that graft polymerization of an appropriate amount of Bis-GMA onto HW could be an effective method to improve the interfacial properties and stability in water of the dental resin composite without compromising the bioactivity. PMID:26042702

  14. Evaluation of Microleakage in Class II Cavities using Packable Composite Restorations with and without use of Liners.

    PubMed

    Arora, Rajesh; Kapur, Ravi; Sibal, Nikhil; Juneja, Sumit

    2012-09-01

    The advent of the esthetic era and advances in adhesive technology saw the emergence of resin composite materials. But the problem of polymerization shrinkage remained. This was due to the contraction of the resin during curing inducing internal and interfacial stresses at the tooth restoration interface, leading to gap formation and subsequent micro-leakage. A number of techniques and modifications in the material have been proposed to minimize polymerization shrinkage and microleakage. In this study, the hypothesis that the placement of resin-modified glass ionomer cement (RMGIC) or flowable composite, as liner, beneath the packable composite, on the gingival surface of the tooth [coronal or apical to cementoenamel junction (CEJ)], could reduce the microleakage in class II composite restorations, was tested. Sixty recently extracted noncarious human mandibular molars were used. The teeth were randomly divided into three groups (20 specimens each): Group I (Filtek P60 with RMGIC liner), group II (Filtek P60 with Filtek Z350 liner) and Group III (Filtek P60 without liner). The teeth of each group were further subdivided into two subgroups (equal number of cavities). Subgroup A gingival seat 1 mm occlusal to CEJ on mesial side. Subgroup B gingival seat 1 mm apical to CEJ on distal side. It was concluded that in class II composite restorations gingival microleakage is more at the dentinal surface than on enamel. The use of a flowable composite and RMGIC, as liners, beneath the packable composite, in class II composite restorations, significantly reduces the microleakage when margins are in dentin, but the reverse is true, when the margins are in enamel. How to cite this article: Arora R, Kapur R, Sibal N, Juneja S. Evaluation of Microleakage in Class II Cavities using Packable Composite Restorations with and without use of Liners. Int J Clin Pediatr Dent 2012;5(3):178-184. PMID:25206164

  15. Replacement of Anterior Composite Resin Restorations Using Conservative Ceramics for Occlusal and Periodontal Rehabilitation: An 18-Month Clinical Follow-Up.

    PubMed

    da Cunha, Leonardo Fernandes; Prochnow, Rayane Alexandra; Costacurta, Adriana Osten; Gonzaga, Carla Castiglia; Correr, Gisele Maria

    2016-01-01

    This case report describes a patient with discolored and fractured composite resin restorations on the anterior teeth in whom substitution was indicated. After wax-up and mock-up, the composite was removed and replaced with minimally invasive ceramic laminates. An established and predictable protocol was performed using resin cement. Minimally invasive ceramic restorations are increasingly being used to replace composite restorations. This treatment improves the occlusal and periodontal aspects during the planning and restorative phases, such as anterior guides, and laterality can be restored easily with ceramic laminates. In addition, the surface smoothness and contour of ceramic restorations do not affect the health of the surrounding periodontal tissues. Here we present the outcome after 18 months of clinical follow-up in a patient in whom composite resin restorations in the anterior teeth were replaced with minimally invasive ceramic laminates. PMID:27555970

  16. Replacement of Anterior Composite Resin Restorations Using Conservative Ceramics for Occlusal and Periodontal Rehabilitation: An 18-Month Clinical Follow-Up

    PubMed Central

    Prochnow, Rayane Alexandra; Costacurta, Adriana Osten; Correr, Gisele Maria

    2016-01-01

    This case report describes a patient with discolored and fractured composite resin restorations on the anterior teeth in whom substitution was indicated. After wax-up and mock-up, the composite was removed and replaced with minimally invasive ceramic laminates. An established and predictable protocol was performed using resin cement. Minimally invasive ceramic restorations are increasingly being used to replace composite restorations. This treatment improves the occlusal and periodontal aspects during the planning and restorative phases, such as anterior guides, and laterality can be restored easily with ceramic laminates. In addition, the surface smoothness and contour of ceramic restorations do not affect the health of the surrounding periodontal tissues. Here we present the outcome after 18 months of clinical follow-up in a patient in whom composite resin restorations in the anterior teeth were replaced with minimally invasive ceramic laminates. PMID:27555970

  17. Influence of eugenol-containing temporary restorations on bond strength of composite to dentin.

    PubMed

    Yap, A U; Shah, K C; Loh, E T; Sim, S S; Tan, C C

    2001-01-01

    This study investigated the influence of eugenol-containing temporary restorations on bond strength of composite to dentin. Thirty-two freshly extracted human molars were embedded and horizontally sectioned at a level 2 mm from the central fossa to obtain a flat dentin surface. The teeth were randomly divided into four groups of eight teeth. Specimens in Group 1 (control) received no pre-treatment with any temporary restorations. Group 2 and 3 specimens were covered with IRM (eugenol-containing) mixed at powder: liquid (P:L) ratio of 10 g: 1 g and 10 g: 2 g, respectively. Specimens in Group 4 were covered with polycarboxylate cement (eugenol-free) mixed at a P:L ratio of 2.85 g: 1 g. The temporary restorations were mechanically removed with an ultrasonic scaler after one-week storage in distilled water at 37 degrees C. The dentin surfaces were cleaned with pumice-water slurry and treated with Scotchbond Multi-Purpose Plus bonding system according to manufacturer's instructions. Composite (Z100) columns (3 mm diameter, 2 mm high) were applied and shear bond testing was carried out after 24 hours storage in distilled water at 37 degrees C using an Instron Universal testing machine with a cross-head speed of 0.5 mm/minute. The mode of failure was examined using a stereomicroscope at X40 magnification. Results were analyzed using one-way ANOVA/Scheffes's post-hoc test at significance level 0.05. Ranking of bond strengths was as follows: Group 1 (22.58 MPa) > Group 2 (21.14 MPa) > Group 4 (15.35 MPa) > Group 3 (13.02 MPa). Group 3 had significantly lower bond strength than Groups 1 and 2. No significant difference in dentin bond strength was observed between the Group 1 (control) and Groups 2 and 4. Although the predominant mode of failure for Groups 1, 2 and 4 was cohesive in dentin, all specimens in Group 3 exhibited adhesive failure. Pre-treatment with polycarboxylate cement or IRM mixed at P:L ratio of 10 g: 1 g did not affect shear bond strength of composite to

  18. Effect of cyclic loading on marginal adaptation and bond strength in direct vs. indirect class II MO composite restorations.

    PubMed

    Aggarwal, Vivek; Logani, Ajay; Jain, Veena; Shah, Naseem

    2008-01-01

    This study evaluated the effect of cyclic loading on the marginal adaptation and microtensile bond strength of direct vs indirect Class II composite restorations in an in-vitro model. Forty Class II cavities were prepared on the mesial surface of extracted human maxillary first premolars and divided into two groups: Group I--direct composite restorations and Group II--indirect composite restorations. Groups I and II were further divided into subgroups: A (without cyclic loading) and B (with cyclic loading of 150,000 cycles at 60N). The gingival margin of the proximal box was evaluated at 200x magnification for marginal adaptation in a low vacuum scanning electron microscope. The restorations were sectioned perpendicular to the bonded surface into 1 mm thickslabs. The slabswere further trimmed at the interface to produce a cross-sectional surface area of approximately 1 mm2. All specimens were subjected to microtensile bond strength testing. The marginal adaptation was analyzed using descriptive studies and bond strength data were analyzed by one-way ANOVA test. The indirect composite restorations performed better under cyclic loading. PMID:18833866

  19. Thermal expansion characteristics of light-cured dental resins and resin composites.

    PubMed

    Sideridou, Irini; Achilias, Dimitris S; Kyrikou, Eleni

    2004-07-01

    The thermal expansion characteristics of dental resins prepared by light-curing of Bis-GMA, TEGDMA, UDMA, Bis-EMA(4) or PCDMA dimethacrylate monomers and of commercial light-cured resin composites (Z-100 MP, Filtek Z-250, Sculpt-It and Alert), the organic matrix resin of which is based on different combinations of the above monomers, were studied by thermomechanical analysis (TMA). This study showed the existence of a glass transition temperature at around 35-47 degrees C for the resins and 40-45 degrees C for the composites; then the coefficient of linear thermal expansion (CLTE) was calculated at the temperature intervals 0-60 degrees C, 0-T(g) and T(g)-60 degrees C. The CLTE values of Bis-GMA, TEGDMA and UDMA resins are similar and lower than those of Bis-EMA (4) and PCDMA resins. The CLTE values of the composites indicated that the major factor that affects the CLTE of a composite is the filler content, but it also seems to be affected by the chemical structure of the matrix resin. TMA on water-saturated samples showed that water desorption takes place during the measurement and that the residual water acts as a plasticizer decreasing the T(g) and increasing the CLTE values. Furthermore, TMA on post-heated samples for 1, 3 or 6h showed, only for the resins, an initial decrease of CLTE and increase of the T(g) after 1h that was not significantly changed after 6h of heating. PMID:14967543

  20. Microleakage and Micrographic Evaluation of Composite Restorations with Various Bases over ZOE Layer in Pulpotomized Primary Molars

    PubMed Central

    Bargrizan, M.; Mirkarimi, M.; Rezamand, M.; Eskandarion, S.

    2011-01-01

    Objective Zinc oxide eugenol (ZOE) under composite restorations should be covered with a suitable material in order to prevent the harmful effect of ZOE on the composite. The aim of this in vitro study was to evaluate microleakage of composite restorations in pulpotomized primary molars with different bases for covering the ZOE layer and to assess the distance between different layers. Materials and Methods Proximo-occlusal cavities were prepared in 78 extracted second primary molars. Carious lesions were removed and pulpotomy was carried out. Zinc oxide eugenol paste was placed in 2-mm thickness. The teeth were randomly divided in 6 groups and restored as follows: 1. Light-cured composite; 2. Resin-modified glass-ionomer and composite resin; 3. Glass-ionomer and composite resin; 4. Light-cured calcium hydroxide and composite resin; 5. Calcium hydroxide and composite resin; 6. Amalgam and composite resin. The restored specimens were thermocycled for 500 cycles (5°C/55°C) and microleakage was assessed by dye penetration technique. Three specimens from each group were processed for scanning electron microscope evaluation to determine the distance between the layers. The results were analyzed by Kruskal-Wallis and Dunn tests. Results Microleakage assessment revealed significant differences between the groups (P=0.04), with the amalgam group exhibiting the lowest microleakage values. In SEM micrographs no significant differences were observed in the distance between ZOE base layers (P=0.94) and base-composite layers (P=0.47); however, the amalgam group had the lowest distances. Conclusion The use of amalgam over zinc oxide eugenol layer in pulpotomized primary molars decreases microleakage. PMID:22509457

  1. Do resin cements influence the cuspal deflection of teeth restored with composite resin inlays?

    PubMed

    da Rosa, Helen C V; Marcondes, Maurem L; de Souza, Niélli C; Weber, João B B; Spohr, Ana M

    2015-04-01

    The aim of this study was to evaluate the influence of different resin cements on the cuspal deflection of endodontically treated teeth restored with composite resin inlays. Sixty upper premolars were randomly divided into five groups (n=12): 1 - sound teeth; 2 - cavity; 3 - Rely X ARC; 4 - RelyX Unicem; 5 - SeT. The teeth from groups 2, 3, 4 and 5 received a MOD preparation and endodontic treatment. Impressions were made with vinyl polysiloxane and poured using type IV die stone in groups 3, 4 and 5. Inlays with composite resin were built over each cast and luted with the resin cements. A 200 N load was applied on the occlusal surface, and cuspal deflection was measured using a micrometer. After 24 h, cuspal deflection was measured again using a 300 N load. The Student t-test showed that there was no statistically significant difference between the 200 N and 300 N occlusal loads only for the sound teeth group (p = 0.389) and the RelyX ARC group (p = 0.188). ANOVA and Tukey'test showed that the sound teeth had the lowest mean cuspal deflection, differing statistically from the other groups (p<0.05). The highest cuspal deflections were obtained in the SeT group and the cavity group, with no statistical difference between them. Intermediate values were obtained in RelyX ARC group and RelyX Unicem group, which differed statistically. The self-adhesive resin cements RelyX Unicem and SeT showed less capacity to maintain the stiffness of the tooth/restoration complex than the conventional resin cement RelyX ARC. PMID:25950160

  2. Restorative Treatment Thresholds for Occlusal Primary Caries by Dentists in “The Dental Practice-Based Research Network”

    PubMed Central

    Gordan, Valeria V; Bader, James D; Garvan, Cynthia W; Richman, Joshua S; Qvist, Vibeke; Fellows, Jeffrey L; Rindal, D. Brad; Gilbert, Gregg H

    2010-01-01

    Objectives (1) Quantify at which carious lesion depths dentists intervene surgically for cases of varying caries penetration and caries risk; (2) Identify characteristics that are associated with surgical intervention. Methods Dentists in a practice-based research network who reported doing at least some restorative dentistry were surveyed. Dentists were asked to indicate whether they would surgically intervene in a series of cases depicting occlusal caries. Each case included a photograph of an occlusal surface displaying typical characteristics of caries penetration, and a written description of a patient at a specific level of caries risk. Using logistic regression, we analyzed associations of surgical treatment with dentist and practice characteristics, and patient caries risk levels. Results 519 DPBRN practitioner-investigators responded, of whom 63% indicated that they would surgically restore lesions located on inner enamel surfaces, and 90% of lesions located in outer dentin surfaces in a low caries risk individual. Regarding individuals at high caries risk, 77% reported that they would surgically restore inner enamel lesions and 94% reported restoring lesions located on the outer dentin surface. Dentists who did not assess caries risk were more likely to intervene on dentin lesions (p=.004). Practitioner-investigators who were in private practice were significantly more likely to intervene surgically on enamel lesions, compared to dentists from large group practices (p<.001). Conclusion Most dentists chose to provide some treatment to lesions that were within the enamel surface. Decisions to intervene surgically in the caries process differ by caries lesion depth, patient caries risk, assessment of caries risk, type of practice model, and percent of patients who self-pay. PMID:20123876

  3. Evaluation of Gingival Microleakage in Class II Composite Restorations with Different Lining Techniques: An In Vitro Study.

    PubMed

    Bore Gowda, Vedavathi; Sreenivasa Murthy, B V; Hegde, Swaroop; Venkataramanaswamy, Swapna Devarasanahalli; Pai, Veena Suresh; Krishna, Rashmi

    2015-01-01

    Aim. To compare the microleakage in class II composite restorations without a liner/with resin modified glass ionomer and flowable composite liner. Method. Forty standardized MO cavities were prepared on human permanent mandibular molars extracted for periodontal reasons and then divided into 4 groups of ten specimens. The cavity preparations were etched, rinsed, blot dried, and light cured and Adper Single Bond 2 is applied. Group 1 is restored with Filtek P60 packable composite in 2 mm oblique increments. Group 2 is precure group where 1 mm Filtek Z350 flowable liner is applied and light cured for 20 sec. Group 3 is the same as Group 2, but the liner was cocured with packable composite. In Group 4, 1 mm RMGIC, Fuji Lining LC is applied and cured for 20 sec. All the teeth were restored as in Group 1. The specimens were coated with nail varnish leaving 1 mm around the restoration, subjected to thermocycling, basic fuchsin dye penetration, sectioned mesiodistally, and observed under a stereomicroscope. Results. The mean leakage scores of the individual study groups were Group 1 (33.40), Group 2 (7.85), Group 3 (16.40), and Group 4 (24.35). Group 1 without a liner showed maximum leakage. Flowable composite liner precured was the best. PMID:26759730

  4. Evaluation of Gingival Microleakage in Class II Composite Restorations with Different Lining Techniques: An In Vitro Study

    PubMed Central

    Bore Gowda, Vedavathi; Sreenivasa Murthy, B. V.; Hegde, Swaroop; Venkataramanaswamy, Swapna Devarasanahalli; Pai, Veena Suresh; Krishna, Rashmi

    2015-01-01

    Aim. To compare the microleakage in class II composite restorations without a liner/with resin modified glass ionomer and flowable composite liner. Method. Forty standardized MO cavities were prepared on human permanent mandibular molars extracted for periodontal reasons and then divided into 4 groups of ten specimens. The cavity preparations were etched, rinsed, blot dried, and light cured and Adper Single Bond 2 is applied. Group 1 is restored with Filtek P60 packable composite in 2 mm oblique increments. Group 2 is precure group where 1 mm Filtek Z350 flowable liner is applied and light cured for 20 sec. Group 3 is the same as Group 2, but the liner was cocured with packable composite. In Group 4, 1 mm RMGIC, Fuji Lining LC is applied and cured for 20 sec. All the teeth were restored as in Group 1. The specimens were coated with nail varnish leaving 1 mm around the restoration, subjected to thermocycling, basic fuchsin dye penetration, sectioned mesiodistally, and observed under a stereomicroscope. Results. The mean leakage scores of the individual study groups were Group 1 (33.40), Group 2 (7.85), Group 3 (16.40), and Group 4 (24.35). Group 1 without a liner showed maximum leakage. Flowable composite liner precured was the best. PMID:26759730

  5. Planning extensive esthetic restorations for anterior teeth: use of waxed-up study casts and composite resin mock-ups.

    PubMed

    Furuse, Adilson Yoshio; Baratto, Samantha Schaffer Pugsley; Spina, Denis Roberto Falcão; Correr, Gisele Maria; da Cunha, Leonardo Fernandes; Gonzaga, Carla Castiglia

    2016-01-01

    The aim of this case report is to highlight the importance of appropriate planning protocols when direct composite resin restorations are used to solve extensive esthetic problems. A 30-year-old patient complained about her small maxillary anterior teeth and short upper lip. All teeth were healthy and light colored, and the patient exhibited good oral hygiene. The anterior teeth were relatively short, resulting in a compromised esthetic relationship between height and width. The maxillary and mandibular right central incisors were in an edge-to-edge relationship. After diagnostic casts and waxed-up study casts were obtained, occlusal adjustment and recontouring of the incisal and labial surfaces of the mandibular right central incisor were performed to increase overjet. To increase the volume of the upper lip, composite resin restorations were planned for the maxillary anterior teeth. To confirm that the contours and color of the new smile were acceptable to the patient, composite resin esthetic mock-ups were made directly in the mouth before the definitive procedure. After definitive restoration of the anterior teeth, additional occlusal adjustments were performed. At the 36-month follow-up, no fracturing or severe wear of the restorations was observed. The restored anterior guidance provided excellent function after 3 years of clinical service. PMID:26742179

  6. Temperature change, dentinal fluid flow and cuspal displacement during resin composite restoration.

    PubMed

    Ratih, D N; Palamara, J E A; Messer, H H

    2007-09-01

    Dentin-bonding agents and resin composite materials typically require light activation for polymerization. Light curing generates heat, which may influence dentinal fluid flow (DFF) and cuspal displacement. This study investigated the relationship among temperature increase, DFF and cuspal displacement in extracted human maxillary premolars with a mesial occlusal distal (MOD) cavity preparation. Two types of curing light were compared. Temperature changes were measured using thermocouples located on the occlusal cavity floor and at the pulp-dentine junction, during polymerization of bonding agent and resin composite material. DFF and cuspal displacement were measured simultaneously using automated flow measurement apparatus and direct current differential transformers respectively. Temperature increases of up to 15 degrees C were recorded during the restoration procedures. A quartz tungsten halogen (QTH) unit produced a significantly greater temperature increase than a light-emitting diode unit and curing of the bonding agent generated less temperature increase than curing of the resin composite. Heating due to exothermic reaction during polymerization of bonding agent and resin was not significantly different between light sources or between bonding and curing (P > 0.05). The QTH unit produced both greater inward fluid flow and cuspal displacement during the irradiation of bonding agent and resin composite than the light-emitting diode unit. There was not a simple relationship between temperature increase, fluid movement and cuspal displacement. From a clinical point of view, the light-emitting diode unit can be considered preferable to the QTH light, because it caused significantly smaller temperature increase, fluid shift and cuspal displacement. PMID:17716269

  7. Composite resin restorations of non-carious cervical lesions in patients with diabetes mellitus and periodontal disease: pilot study.

    PubMed

    Nassar, Carlos A; Nassar, Patrícia O; Secundes, Mayron B; Busato, Priscilla do Monte Ribeiro; Camilotti, Veridiana

    2012-01-01

    Diabetes mellitus is a set of metabolic diseases characterized by hyperglycemia resulting from absolute or relative deficiency in insulin secretion by the pancreas and/or impaired insulin action in target tissues. Oral health maintenance through health care, as well as metabolic control are important measures for the overall health of diabetic patients. The objective of this study was to determine the relationship between biocompatibility of composite resin restorations with different nanoparticles, polishing in abfraction lesions in anterior and posterior teeth with periodontal tissues in patients with diabetes mellitus. We selected 20 patients--10 patients with diabetes mellitus and 10 patients without diabetes mellitus-, but with a total of 30 restorations in each group receiving composite resin restorations, who were evaluated for periodontal purposes: Plaque Index, Gingival Index; Probing Depth, Clinical Attachment Level and Bleeding on Probing. In addition, the restorations will receive assessments according to criteria for Marginal Adaptation, Anatomical Shape, Marginal Discoloration, ormation of caries, Post-operative Sensitivity and Retention. The total period was 90 days. The results showed a significant improvement in periodontal parameters assessed (p < 0.05) in both groups. With regard to assessments of the restorations, it was observed that there was no statistically significant difference (p > 0.05) among all criteria evaluated within the 90-day period. Thus, we conclude that in a short period (90 days) there is clinical biocompatibility of composite resin with nanoparticles restorations in abfraction lesions and periodontal tissues of patients with diabetes mellitus, regardless the type of polish these restorations receive. PMID:23798074

  8. In Situ Response of Nanostructured Hybrid Fluoridated Restorative Composites on Enamel Demineralization, Surface Roughness and Ion Release.

    PubMed

    Melo, Mary A S; Codes, Bruna M; Passos, Vanara F; Lima, Juliana P M; Rodrigues, Lidiany K A

    2014-12-01

    Recurrent caries at the tooth-restoration margins is the main reason for composite failure. Fluoride-releasing nanohybrid composite resin may reduce the recurrent caries rates. A fluoride-releasing resin (FCR) and non-fluoride-releasing resin (CR) were tested using an in situ model. Demineralization (ΔS), ion release and surface roughness of composite specimens were determined. The F concentration in the group FCR was higher than the CR group. ΔS (Mean ± SD) was 2579 ± 1582 and 1705 ± 1292, respectively, for FCR and CR. Surfaces roughness was altered by biofilm accumulation. The hybrid fluorated restorative composites containing nanoparticles have a slight anticaries action without alteration of surface smoothness of the material. PMID:26466443

  9. Five year evaluation of class III composite resin restorations in cavities pre-treated with an oxalic- or a phosphoric acid conditioner.

    PubMed

    van Dijken, J W; Olofsson, A L; Holm, C

    1999-05-01

    An oxalic acid solution has been proposed as a conditioning agent for resin composite restorations in two commercial adhesive systems. The durability of 163 class III restorations, including 12 class IV restorations, in cavities pre-treated with an oxalic acid total etch technique or an enamel etch with phosphoric acid was studied. Each of 52 patients received at least one of each of three experimental restorations. The restorations were evaluated yearly with slightly modified United States Public Health Service (USPHS) criteria. After 5 years 95% of the restorations were evaluated as acceptable. Reasons for failure were the fracture of four fillings, including three class IV, secondary caries contiguous to two fillings and a non-acceptable colour match for one restoration. For eight class III restorations a fracture of the incisal tooth structure was registered. No differences were seen between the three experimental restorations. PMID:10373082

  10. Comparison of microleakage in Class II cavities restored with silorane-based and methacrylate-based composite resins using different restorative techniques over time

    PubMed Central

    Khosravi, Kazem; Mousavinasab, Seyed-Mostafa; Samani, Mahsa Sahraneshin

    2015-01-01

    Background: Despite the growing tendency toward tooth-colored restorations in dentistry, polymerization shrinkage and subsequent marginal microleakage remains a problem. The aim of this in vitro study was to compare microleakage between silorane-based and methacrylate-based composite resins at different time intervals and with different restorative techniques. Materials and Methods: In this in vitro study, 108 sound extracted human molar teeth were used. Mesial and distal proximal class II boxes with dimensions of 1.5 mm depth and 4 mm width were prepared. The gingival margins of all cavities were 1 mm below the cement enamel junction. The teeth were randomly divided into three groups based on test materials. In the first group, the teeth were restored by a nanocomposite (Filtek Z350XT, 3MESPE) and SE Bond adhesive (Kuraray, Japan), in the second group, the teeth were restored with a silorane-based (Filtek P90, 3MESPE) and Filtek P90 Adhesive (3M ESPE, USA) and in the third group, the teeth were restored with a microhybrid posterior composite resin (Filtek P60, 3MESPE) and SE Bond adhesive (Kuraray, Japan). Half of the proximal cavities in each of these three groups were restored in two horizontal layers and the other half in four horizontal layers. After a period of aging (24-h, 3-month and 6-month) in water and then application of 500 thermal cycles, the teeth were immersed for 24-h in 0.5% fuchsin and evaluated under a stereomicroscope at ×36 magnification to evaluate leakage in gingival margin. Data was statistically analyzed using Kruskal-Wallis and Mann-Whitney U-tests. P ≤ 0.05 was considered as significant. Results: In Z350XT statistically significant differences were observed in microleakage in comparison of 24-h and 6-month intervals (P = 0.01) that was higher in 6-month. Comparison of microleakage in P90 and P60 composite resins was also statistically significant and was less in P90. Microleakage was not significantly different between P90 and Z350XT

  11. Further study of restored and un-restored teeth subjected to high temperatures.

    PubMed

    Merlati, G; Savlo, C; Danesino, P; Fassina, G; Menghini, P

    2004-12-01

    Forensic dentistry has been shown to be of fundamental importance in medico-legal investigations aimed at identifying human remains involving high temperature incidents because dental remains and prosthetic devices are resistant to quite high thermal change. In this project we studied teeth containing class I and V amalgam and composite fillings and compared them to un-restored teeth when exposed to high temperatures. Twenty five un-restored teeth, 25 teeth with class I amalgam restorations, 25 teeth with class V amalgam restorations and 25 teeth with class I composite fillings were placed in a furnace and heated at a rate of 30 degrees C/min. The effects at the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined macroscopically and then observed microscopically by means of a stereomicroscope. Our observations showed that the class I amalgam restorations at the different temperature levels remained in place, maintaining their shape despite disintegration of the crowns, whilst the class I composite restorations remained in place but in an altered shape. Comparing restored with un-restored teeth we observed different responses in crown disintegration at the different temperature levels. PMID:16223018

  12. Characterization of morphology and composition of inorganic fillers in dental alginates.

    PubMed

    Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

    2014-01-01

    Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450(°)C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C-81.59%, H-79.89%, O-78.87%, H5-77.95%, JP-66.88%, wt). The filler fractions in volume (vt) were as follows: H5-84.85%, JP-74.76%, H-70.03%, O-68.31%, and C-56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

  13. Inconsistency in the strength testing of dental resin-based composites among researchers

    PubMed Central

    Kumar, Naresh

    2013-01-01

    The aims of this paper were to review the current strength testing methods of the dental resin-based composites (RBCs) and to explore the inconsistencies with regard to strength testing among researchers. Data selection/extraction: An outline of the most relevant aspects of RBCs was created, and a subsequent literature search for articles published during last four decades (1970-2010) was conducted using the databases, namely PubMed, Science Direct and ISI Web of Knowledge. Conclusion: The literature review highlighted a lack of consensus among researchers regarding the reliability of ISO recommended three-point flexure strength testing method. Several investigators have used Weibull statistics for the analysis of RBCs strength data, however their applicability might be questioned as many RBCs contain greater resin content and may exhibit sufficient viscous deformation prior to brittle failure. In addition, variability in the selection of cross-head speed and mould material for strength testing was evident which may lead to variation in the strength data and render the interpretation difficult among researchers. PMID:24353541

  14. Characterization of Morphology and Composition of Inorganic Fillers in Dental Alginates

    PubMed Central

    Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

    2014-01-01

    Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450°C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C—81.59%, H—79.89%, O—78.87%, H5—77.95%, JP—66.88%, wt). The filler fractions in volume (vt) were as follows: H5—84.85%, JP—74.76%, H—70.03%, O—68.31%, and C—56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

  15. Restoration of the immune functions in aged mice by supplementation with a new herbal composition, HemoHIM.

    PubMed

    Park, Hae-Ran; Jo, Sung-Kee; Jung, Uhee; Yee, Sung-Tae

    2008-01-01

    The effect of a new herbal composition, HemoHIM, on immune functions was examined in aged mice, in which various immune responses had been impaired. The composition HemoHIM was prepared by adding the ethanol-insoluble fraction to the total water extract of a mixture of three edible herbs, Angelica Radix, Cnidium Rhizoma and Paeonia Radix. Supplementation to the aged mice with HemoHIM restored the proliferative response and cytokine production of splenocytes with a response to ConA. Also, HemoHIM recovered the NK cell activity which had been impaired in the aged mice. Meanwhile aging is known to reduce the Th1-like function, but not the Th2-like function, resulting in a Th1/Th2 imbalance. HemoHIM restored the Th1/Th2 balance in the aged mice through enhanced IFN-gamma and IgG2a production, and conversely a reduced IL-4 and IgG1 production. It was found that one factor for the Th1/Th2 imbalance in the aged mice was a lower production of IL-12p70. However, HemoHIM restored the IL-12p70 production in the aged mice. These results suggested that HemoHIM was effective for the restoration of impaired immune functions of the aged mice and therefore could be a good recommendation for immune restoration in elderly humans. PMID:17705143

  16. Improved performance of Bis-GMA/TEGDMA dental composites by net-like structures formed from SiO2 nanofiber fillers.

    PubMed

    Wang, Xiaoyan; Cai, Qing; Zhang, Xuehui; Wei, Yan; Xu, Mingming; Yang, Xiaoping; Ma, Qi; Cheng, Yali; Deng, Xuliang

    2016-02-01

    The major objective of this study was to explore the effects of silicon dioxide (SiO2) nanofibers on the performance of 2, 2-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA)/tri-(ethyleneglycol) dimethacrylate (TEGDMA) dental composites. At first, the mechanical properties of Bis-GMA/TEGDMA (50/50, w/w) resins containing different contents of SiO2 nanofibers were evaluated to identify the appropriate composition to achieve the significant reinforcing effect. Secondly, optimized contents (5 or 10wt.%) of SiO2 nanofibers were mixed into resins together with SiO2 microparticles, which was 60wt.% of the resin. Controls for comparison were Bis-GMA/TEGDMA resins containing only SiO2 microparticles (60wt.%) or with additional SiO2 nanoparticles (5 or 10wt.%). Properties including abrasion, polymerization shrinkage and mechanical properties were evaluated to determine the contribution of SiO2 nanofibers. In comparison with SiO2 nanoparticles, SiO2 nanofibers improved the overall performance of Bis-GMA/TEGDMA composite resins, especially in improving abrasion resistance and decreasing polymerization shrinkage. The explanations were that one-dimensional SiO2 nanofibers were able to shield particular fillers from being abraded off, and able to form a kind of overlapped fibrous network to resist polymerization shrinkage. With these approaches, SiO2 nanofiber-containing Bis-GMA composite resins were envisioned a promising choice to achieve long-term durable restorations in clinical therapies. PMID:26652397

  17. Effects of elevated temperatures on different restorative materials: An aid to forensic identification processes

    PubMed Central

    Pol, Chetan A.; Ghige, Suvarna K.; Gosavi, Suchitra R.; Hazarey, Vinay K.

    2015-01-01

    Background: Heat-induced alterations to dental and restorative materials can be of great interest to forensic dentistry. Knowing the specific optical behavior of dental materials can be of high importance as recognition of changes induced by high temperatures can lead to the determination of material which was used in a dental restoration, facilitating identification of burned human remains. Aim: To observe the effects of predetermined temperatures (200°C–400°C–600°C–800°C–1000°C) on unrestored teeth and different restorative materials macroscopically and then examine them under a stereomicroscope for the purpose of identification. Materials and Methods: The study was conducted on 375 extracted teeth which were divided into five groups of 75 teeth each as follows: group 1- unrestored teeth, group 2- teeth restored with all-ceramic crowns, Group 3- with class I silver amalgam filling, group 4- with class I composite restoration, and group 5- with class I glass ionomer cement restoration. Results: Unrestored and restored teeth display a series of specific macroscopic & stereomicroscopic structural changes for each range of temperature. Conclusion: Dental tissues and restorative materials undergo a series of changes which correlate well with the various temperatures to which they were exposed. These changes are a consequence of the nature of the materials and their physicochemical characteristics. PMID:26005305

  18. Influence of mouth rinses on the surface hardness of dental resin nano-composite

    PubMed Central

    Khan, Aftab Ahmed; Siddiqui, Adel Zia; Mohsin, Syed Fareed; Al-Kheraif, Abdulaziz A.

    2015-01-01

    Objective: The aim of this research was to assess the effect of mouth rinses with and without alcohol on the hardness of dental nano-filled composite. Methods: The micro-hardness of fifty circular disk shaped specimens of 7 mm x 2 mm were measured after 14 days. Specimens were immersed into alcohol containing (Listerine and Colgate Perioguard) and alcohol-free (Prodent and Sensodyne Oral antiseptic) mouth rinse solutions. Artificial saliva served as the control. Vickers Micro-hardness was measured with a 30gram load for 30 seconds dwell time by using a diamond indenter. Significant differences were represented by p<0.05, whereas highly significant difference represented by p<0.01. The level of significance (p) was calculated with the help of repeated measure ANOVA. For multiple comparisons, Tukey’s multiple comparison test was used. Results: Statistical analysis revealed highly significant difference between specimens immersed in artificial saliva (control) and Listerine (p<0.01). Whereas significant difference were observed between control and Colgate Periogard (p<0.05). However, no significant difference was observed on comparing Prodent and Sensodyne Oral antiseptic mouth rinses with control group(p>0.05). Control specimens depicted highest value of micro-hardness(60.5746 ± 3.2703) compared to the lowest value seen in specimens immersed in Listerine solvent(54.4687 ± 1.0937). Conclusion: Alcohol containing mouth rinsing solutions have more deleterious effect on hardness of nano composites as compared to alcohol-free mouth rinses. PMID:26870121

  19. Fracture toughness determination of ceramic and resin-based dental composites.

    PubMed

    Kvam, K

    1992-01-01

    A new method has been developed for Klc determinations of brittle materials with precracks introduced by indentations. A reference glass, five ceramic materials, and one resin-based composite were tested. Knoop hardness indentations were made with a load of 49 N in a line from edge to edge vertical to the long axis on one surface of four-point flexure bars, to make a continuous crack under the indentations. Five specimens of each material were fractured in a four-point bend test with the line of indentations placed in the zone of constant and maximum tensile stress. Separate unfractured specimens were ground and polished to expose and measure the preformed continuous crack. The mean of six crack-depth measurements was used together with the fracture load and the dimensions of the bend specimens to calculate the fracture toughness, Klc of each material. The determined Klc value (x +/- SD) for the reference glass was 0.81 +/- .24 MPa m1/2 and corresponds to previous studies. The resin-based composite material, Silux Plus, had a value of 1.04 +/- 0.14 MPa m1/2. The Klc values (MPa m1/2) were 0.94 +/- 0.31 for Dicor, 1.41 +/- 0.18 for Cerestore, 1.50 +/- 0.29 for NBK-1000, 1.60 +/- 0.17 for Vitadur-N and 2.14 +/- 0.14 for Hi-Ceram. Hi-Ceram had significantly higher Klc values than the other materials. The new method seemed to be of value in determining the fracture toughness of non-metallic dental materials. PMID:1550892

  20. Erosive potential of commonly used beverages, medicated syrup, and their effects on dental enamel with and without restoration: An in vitro study

    PubMed Central

    Trivedi, Krishna; Bhaskar, Vijay; Ganesh, Mahadevan; Venkataraghavan, Karthik; Choudhary, Prashant; Shah, Shalin; Krishnan, Ramesh

    2015-01-01

    Aim: This study evaluates erosive potential of commonly used beverages, medicated syrup, and their effects on dental enamel with and without restoration in vitro. Materials and Methods: Test medias used in this study included carbonated beverage, noncarbonated beverage, high-energy sports drink medicated cough syrup, distilled water as the control. A total of 110 previously extracted human premolar teeth were selected for the study. Teeth were randomly divided into two groups. Test specimens were randomly distributed to five beverages groups and comprised 12 specimens per group. Surface roughness (profilometer) readings were performed at baseline and again, following immersion for 14 days (24 h/day). Microleakage was evaluated. The results obtained were analyzed for statistical significance using SPSS-PC package using the multiple factor ANOVA at a significance level of P < 0.05. Paired t-test, Friedman test ranks, and Wilcoxon signed ranks test. Results: For surface roughness high-energy sports drink and noncarbonated beverage showed the highly significant difference with P values of 0.000 and 0.000, respectively compared to other test media. For microleakage high-energy sports drink had significant difference in comparison to noncarbonated beverage (P = 0.002), medicated syrup (P = 0.000), and distilled water (P = 0.000). Conclusion: High-energy sports drink showed highest surface roughness value and microleakage score among all test media and thus greater erosive potential to enamel while medicated syrup showed least surface roughness value and microleakage among all test media. PMID:26538901

  1. The effect of various sandblasting conditions on surface changes of dental zirconia and shear bond strength between zirconia core and indirect composite resin

    PubMed Central

    Su, Naichuan; Yue, Li; Liao, Yunmao; Liu, Wenjia; Zhang, Hai; Li, Xin

    2015-01-01

    PURPOSE To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and 110 µm. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (α=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from 50 µm to 110 µm. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 µm is recommended for dental applications to improve the bonding between zirconia core and ICR. PMID:26140173

  2. Comparison of fracture resistance of endodontically treated teeth restored with nanohybrid, silorane, and fiber reinforced composite: An in vitro study

    PubMed Central

    Bilgi, Priyanka Shripad; Shah, Nimisha Chinmay; Patel, Parth Pinakinbhai; Vaid, Deepa S

    2016-01-01

    Background: The present study was undertaken to evaluate the most suitable restorative for badly mutilated endodontically treated teeth. Aims: To evaluate and compare the fracture resistance of endodontically treated premolars restored with conventional nanohybrid, silorane composite with glass fibers and newer fiber-reinforced composite in mesio-occluso-distal (MOD) cavities. Materials and Methods: Sixty extracted human maxillary premolars were selected. Fifteen intact teeth served as positive controls (Group 1). Endodontic therapy was done in the remaining 45 teeth. MOD cavities were prepared in all the teeth with standardized dimensions and were randomly divided into three groups (Group 2 - nanohybrid + glass fibers, Group 3 - silorane + glass fibers, and Group 4 – fiber-reinforced composite). Restorations were done for all groups. Fracture resistance was measured by Instron universal testing machine. Statistical Analysis Used: One-way anova test and Tukey's post hoc test. Results: Highest fracture resistance was shown by intact teeth group followed by fiber-reinforced composite, nanohybrid, and silorane, respectively. Statistically Significant difference was revealed by anova test (P < 0.0001) and Tukey's post hoc test (P < 0.0001). Conclusions: Among the experimental groups, fiber-reinforced composite showed the highest fracture resistance. Statistically significant difference was observed for all the groups. PMID:27563188

  3. Effect of Cavity Design on the Strength of Direct Posterior Composite Restorations: An Empirical and FEM Analysis

    PubMed Central

    Anand, V. Susila; Kavitha, C.; Subbarao, C. V.

    2011-01-01

    The aim of the present study was to verify the hypothesis that cavity design does not affect the strength of direct composite restorations as do material properties. Finite element modeling (FEM) and empirical testing were done for two cavity designs: a box shape (cube) and a concave shape (U). Two microhybrid composites were used to prepare the samples with the help of split stainless steel moulds. Compressive strength was tested. The results were statistically analyzed. Both FEA and empirical testing were complementary to each other in that the concave shape showed a significantly higher strength than box. Material properties affected the values only when box shape was used. The null hypothesis is thus rejected, and it is concluded that design significantly affects the strength of direct composite restorations. PMID:22216030

  4. Effect of Cavity Design on the Strength of Direct Posterior Composite Restorations: An Empirical and FEM Analysis.

    PubMed

    Anand, V Susila; Kavitha, C; Subbarao, C V

    2011-01-01

    The aim of the present study was to verify the hypothesis that cavity design does not affect the strength of direct composite restorations as do material properties. Finite element modeling (FEM) and empirical testing were done for two cavity designs: a box shape (cube) and a concave shape (U). Two microhybrid composites were used to prepare the samples with the help of split stainless steel moulds. Compressive strength was tested. The results were statistically analyzed. Both FEA and empirical testing were complementary to each other in that the concave shape showed a significantly higher strength than box. Material properties affected the values only when box shape was used. The null hypothesis is thus rejected, and it is concluded that design significantly affects the strength of direct composite restorations. PMID:22216030

  5. A comparative in vitro study of microleakage by a radioactive isotope and compressive strength of three nanofilled composite resin restorations

    PubMed Central

    Gogna, Rupika; Jagadis, S; Shashikal, K

    2011-01-01

    Aim: This study compares the compressive strength and microleakage of three nanofilled composites using radioactive isotope Ca45. Materials and Methods: Thirty-six freshly extracted human premolars were used in this study. Standardized Class I preparation was carried out and then randomly divided into three different groups: A, B, and C with 12 teeth in each group which were restored with nanofilled composite restoration and then subjected to thermocycling. Microleakage was tested using radioactive isotope Ca45. Kruskal–Wallis and Mann–Whitney tests were used to compare the microleakage scores of the three groups. For measuring the compressive strength of three nanofilled composite resin restorations, 12 specimens of each material were prepared in customized stainless steel cylindrical moulds of 6 mm ×4 mm. The compressive test was performed using the Universal Testing Machine. The values were analyzed with ANOVA and Bonferroni's test. Results: The findings of this study indicate that the synergy has the least microleakage and highest compressive strength followed by the Grandio and Filtek Z-350. Conclusions: Introduction of nanocomposites (packable) appears to have improved the performance of both anterior and posterior restorations with regard to mechanical properties, marginal integrity, and esthetics. PMID:21814351

  6. Effect of Er,Cr:YSGG laser on the surface of composite restoratives during in-office tooth bleaching.

    PubMed

    Dionysopoulos, Dimitrios; Strakas, Dimitrios; Tsitrou, Effrosyni; Tolidis, Kosmas; Koumpia, Effimia

    2016-07-01

    The aim of this in vitro study was to investigate the effect of Er,Cr:YSGG laser on the surface roughness and microhardness of various composite restoratives during in-office tooth bleaching. Five highly viscous composite restoratives and three flowable composite restoratives were investigated. Thirty cylindrical specimens of each material were made using Teflon molds. The specimens of each composite were randomly divided into three groups (n = 10). Group 1 specimens did not receive bleaching treatment, group 2 received a conventional in-office bleaching treatment, and group 3 received a laser-assisted in-office bleaching treatment using an Er,Cr:YSGG laser. Two-way ANOVA was used to determine significant interactions between materials and bleaching methods. One-way ANOVA and Tukey's post hoc test were used to compare the mean surface microhardness and roughness between materials for each treatment group (a = 0.05). Τhere were no significant differences in surface microhardness between the two bleached experimental groups for all the tested composites (p > 0.05). The reduction of surface microhardness after bleaching procedures ranged from 0.72 to 16.93 % for the specimens received conventional treatment and from 1.30 to 11.51 % for those received laser-assisted treatment. Moreover, there were no significant differences in Ra values between the experimental groups (p > 0.05) in all cases. The increase of surface roughness after the bleaching treatments was negligible and was between 0.43 and 4.78 %. The use of Er,Cr:YSGG laser during in-office tooth bleaching treatment did not affect the surface microhardness and roughness of the tested composite restorative materials. PMID:27056698

  7. Dental erosion in children: a literature review.

    PubMed

    Linnett, V; Seow, W K

    2001-01-01

    Epidemiological studies have shown that the prevalence of dental erosion in children varies widely between 2 and 57%. Changes seen in dental erosion range from removal of surface characteristics to extensive loss of tooth tissue with pulp exposure and abscess formation. Symptoms of dental erosion range from sensitivity to severe pain associated with pulp exposure. The etiology of dental erosion is dependent on the presence of extrinsic or intrinsic acid in the oral environment. Extrinsic sources of acids in children include frequent consumption of acidic foods and drinks, and acidic medications. Regurgitation of gastric contents into the mouth, as occurs in gastroesophageal reflux, is the most common source of intrinsic acid in children. A multitude of factors may modify the erosion process, such as saliva, oral hygiene practices, and presence or absence of fluoride. When dental erosion is diagnosed, it is important to investigate and identify the acid source, and to determine if the process is ongoing. The aim of treatment is to eliminate the cause of acid exposure, and to minimize the effects of acid exposure where it is not possible to remove the acid source. Restoration of the dentition involves stainless steel crowns to restore lost vertical dimension, and composite resin for esthetics. PMID:11242729

  8. Critical appraisal: dental amalgam update--part II: biological effects.

    PubMed

    Wahl, Michael J; Swift, Edward J

    2013-12-01

    Dental amalgam restorations have been controversial for over 150 years. In Part I of this Critical Appraisal, the clinical efficacy of dental amalgam was updated. Here in Part II, the biological effects of dental amalgam are addressed. PMID:24320063

  9. Polymer grafted hydroxyapatite whisker as a filler for dental composite resin with enhanced physical and mechanical properties.

    PubMed

    Liu, Fengwei; Wang, Ruili; Cheng, Yanhua; Jiang, Xiaoze; Zhang, Qinghong; Zhu, Meifang

    2013-12-01

    The objective of this study was to investigate the effect of surface graft polymerization of hydroxyapatite whisker (HW) on physical and mechanical properties of dental composite resin. Poly bisphenol A glycidyl methacrylate (Poly(Bis-GMA)) was grafted onto silanized hydroxyapatite whisker (SHW) via solution polymerization and the amount of the Poly(Bis-GMA) on the surface was effectively controlled by polymerization time. The obtained poly(Bis-GMA) grafted hydroxyapatite whisker (PGHW) with different polymer contents was filled into a resin matrix respectively, meanwhile the composites with HW and with SHW served as controls. Monomer conversion was characterized by Fourier transform infrared spectroscopy (FTIR) and volume shrinkage of the composite resin was measured with a density tester. Mechanical properties were tested with a universal testing machine. The results indicated that the composite filled with PGHW-1h (graft ratio of poly(Bis-GMA): 8.5 wt.%) showed lower shrinkage and better mechanical properties, improving flexural strength by 6.5% and 11.9% compared with SHW filled composite and HW filled composite, respectively. However, PGHW with higher graft ratios aggregated seriously and formed defects in the composite, leading to deterioration of mechanical properties. It was revealed that the poly(Bis-GMA) on the surface of PGHW acted as a functional transition layer and enhanced interfacial compatibility and interaction between whisker and resin matrix, which facilitated the dispersion of PGHW in the composite and decreased the composite shrinkage. Thus, the graft polymerization of Bis-GMA on the surface of filler might be a promising modification method for the fabrication of dental materials. PMID:24094216

  10. Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

    SciTech Connect

    Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; Vaudin, Mark D.; Skrtic, Drago; Antonucci, Joseph M.; Hoffman, Kathleen M.; Giuseppetti, Anthony A.; Ilavsky, Jan

    2014-07-28

    Our objective was to investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials. Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to local structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significantly, for the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.

  11. Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

    DOE PAGESBeta

    Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; Vaudin, Mark D.; Skrtic, Drago; Antonucci, Joseph M.; Hoffman, Kathleen M.; Giuseppetti, Anthony A.; Ilavsky, Jan

    2014-07-28

    Our objective was to investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials. Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to localmore » structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significantly, for the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.« less