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Sample records for dental veneers

  1. Advances in dental veneers: materials, applications, and techniques

    PubMed Central

    Pini, Núbia Pavesi; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite; Lovadino, José Roberto; Terada, Raquel Sano Suga; Pascotto, Renata Corrêa

    2012-01-01

    Laminate veneers are a conservative treatment of unaesthetic anterior teeth. The continued development of dental ceramics offers clinicians many options for creating highly aesthetic and functional porcelain veneers. This evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case. The current literature was reviewed to search for the most important parameters determining the long-term success, correct application, and clinical limitations of porcelain veneers. PMID:23674920

  2. Tribological behaviour of unveneered and veneered lithium disilicate dental material.

    PubMed

    Figueiredo-Pina, C G; Patas, N; Canhoto, J; Cláudio, R; Olhero, S M; Serro, A P; Ferro, A C; Guedes, M

    2016-01-01

    The friction and wear behaviour of a lithium disilicate dental ceramic against natural dental enamel is studied, including the effect of the presence of a fluorapatite veneering upon the tribological properties of the material. The tribological behaviour was assessed using reciprocating pin-on-plate test configuration, at pH 3 and pH 7. The surface energy of the plates was determined, as well as the zeta potential of fluorapatite, lithium disilicate and enamel particles in artificial saliva. It was found that the friction and wear behaviour of the tested enamel/plate material tribocouples is less severe in unveneered plates. Initial surface roughness of the plate does not affect wear results. However the topography of the resulting wear track affects the corresponding wear loss: a smoother final wear track is associated with lower wear. The surface topography of the wear track, and thus the tribological performance of the tested materials, is very sensitive to the pH of the sliding solution. This is because the dissolution trend, wettability and surface charge of the used materials are pH dependent. Overall friction and wear are higher under basic pH conditions, especially when plates are veneered. A wear model is proposed that correlates the effect of the described parameters with the observed tribological behaviour at pH 7. Attained results show that fluorapatite coating of lithium disilicate dental crowns affects tooth/crown wear behaviour, resulting in increased wear of both the artificial crown and the opposing natural teeth. Coating should therefore be avoided in occlusal crown surfaces. PMID:26342288

  3. Veneers

    MedlinePlus

    ... Risk for Early Childhood Tooth Decay? What is Dental Amalgam (Silver Filling)? How Do I Care for My Child's Baby Teeth? What is Orofacial Pain? Pacifiers Have Negative and Positive Effects Learn what ...

  4. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    NASA Astrophysics Data System (ADS)

    Wananuruksawong, R.; Jinawath, S.; Padipatvuthikul, P.; Wasanapiarnpong, T.

    2011-10-01

    Silicon nitride (Si3N4) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si3N4 ceramic as a dental core material. The white Si3N4 was prepared by pressureless sintering at relative low sintering temperature of 1650 °C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si3N4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si3N4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (<150 micrometer, Pyrex) with 5 wt% of zirconia powder (3 wt% Y2O3 - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si3N4 specimens, the firing was performed in electric tube furnace between 1000-1200°C. The veneered specimens fired at 1100°C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98×10-6 °C-1, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  5. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics.

    PubMed

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l’Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a shifts (D65 to A switch) or by the CIE b shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings. PMID:25247394

  6. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l'Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a* shifts (D65 to A switch) or by the CIE b* shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  7. Effect of metal primers and tarnish treatment on bonding between dental alloys and veneer resin

    PubMed Central

    Choo, Seung-Sik; Huh, Yoon-Hyuk; Cho, Lee-Ra

    2015-01-01

    PURPOSE The aim of this study was to evaluate the effect of metal primers on the bonding of dental alloys and veneer resin. Polyvinylpyrrolidone solution's tarnish effect on bonding strength was also investigated. MATERIALS AND METHODS Disk-shape metal specimens (diameter 8 mm, thickness 1.5 mm) were made from 3 kinds of alloy (Co-Cr, Ti and Au-Ag-Pd alloy) and divided into 4 groups per each alloy. Half specimens (n=12 per group) in tarnished group were immersed into polyvinylpyrrolidone solution for 24 hours. In Co-Cr and Ti-alloy, Alloy Primer (MDP + VBATDT) and MAC-Bond II (MAC-10) were applied, while Alloy Primer and V-Primer (VBATDT) were applied to Au-Ag-Pd alloys. After surface treatment, veneering composite resin were applied and shear bond strength test were conducted. RESULTS Alloy Primer showed higher shear bond strength than MAC-Bond II in Co-Cr alloys and Au-Ag-Pd alloy (P<.05). However, in Ti alloy, there was no significant difference between Alloy Primer and MAC-Bond II. Tarnished Co-Cr and Au-Ag-Pd alloy surfaces presented significantly decreased shear bond strength. CONCLUSION Combined use of MDP and VBATDT were effective in bonding of the resin to Co-Cr and Au-Ag-Pd alloy. Tarnish using polyvinylpyrrolidone solution negatively affected on the bonding of veneer resin to Co-Cr and Au-Ag-Pd alloys. PMID:26576256

  8. Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report

    PubMed Central

    Bissasu, Sami M; Al-houri, Nabil A

    2014-01-01

    Key Clinical Message This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient. PMID:25356269

  9. Reliability and failure modes of implant-supported zirconium-oxide fixed dental prostheses related to veneering techniques

    PubMed Central

    Baldassarri, Marta; Zhang, Yu; Thompson, Van P.; Rekow, Elizabeth D.; Stappert, Christian F. J.

    2011-01-01

    Summary Objectives To compare fatigue failure modes and reliability of hand-veneered and over-pressed implant-supported three-unit zirconium-oxide fixed-dental-prostheses(FDPs). Methods Sixty-four custom-made zirconium-oxide abutments (n=32/group) and thirty-two zirconium-oxide FDP-frameworks were CAD/CAM manufactured. Frameworks were veneered with hand-built up or over-pressed porcelain (n=16/group). Step-stress-accelerated-life-testing (SSALT) was performed in water applying a distributed contact load at the buccal cusp-pontic-area. Post failure examinations were carried out using optical (polarized-reflected-light) and scanning electron microscopy (SEM) to visualize crack propagation and failure modes. Reliability was compared using cumulative-damage step-stress analysis (Alta-7-Pro, Reliasoft). Results Crack propagation was observed in the veneering porcelain during fatigue. The majority of zirconium-oxide FDPs demonstrated porcelain chipping as the dominant failure mode. Nevertheless, fracture of the zirconium-oxide frameworks was also observed. Over-pressed FDPs failed earlier at a mean failure load of 696 ± 149 N relative to hand-veneered at 882 ± 61 N (profile I). Weibull-stress-number of cycles-unreliability-curves were generated. The reliability (2-sided at 90% confidence bounds) for a 400N load at 100K cycles indicated values of 0.84 (0.98-0.24) for the hand-veneered FDPs and 0.50 (0.82-0.09) for their over-pressed counterparts. Conclusions Both zirconium-oxide FDP systems were resistant under accelerated-life-time-testing. Over-pressed specimens were more susceptible to fatigue loading with earlier veneer chipping. PMID:21557985

  10. 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

  11. Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

    PubMed

    Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

    2016-01-01

    The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and P<0.001, respectively). This study showed that aluminosilicate sol-gel dip coating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain. PMID:27478376

  12. Sol–gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain

    PubMed Central

    Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

    2016-01-01

    The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol–gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia–porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and P<0.001, respectively). This study showed that aluminosilicate sol–gel dip coating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain. PMID:27478376

  13. Ceramic veneers with minimum preparation

    PubMed Central

    da Cunha, Leonardo Fernandes; Reis, Rachelle; Santana, Lino; Romanini, Jose Carlos; Carvalho, Ricardo Marins; Furuse, Adilson Yoshio

    2013-01-01

    The aim of this article is to describe the possibility of improving dental esthetics with low-thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative treatment also improved the function of the anterior guidance. It can be concluded that the conservative use of minimum thickness ceramic laminate veneers may provide satisfactory esthetic outcomes while preserving the dental structure. PMID:24932126

  14. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers

    PubMed Central

    Mahmood, Deyar Jallal Hadi; Linderoth, Ewa H; Wennerberg, Ann; Vult Von Steyern, Per

    2016-01-01

    Aim To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) fixed dental prostheses (FDPs) with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. Materials and methods A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1–7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8–11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. Results There was a significant difference (P<0.05) between the core designs, but not between the different types of Y-TZP materials. The split-file designs with VITABLOCS® (1,806±165 N) and e.max® ZirPress (1,854±115 N) and the state-of-the-art design with VITA VM® 9 (1,849±150 N) demonstrated the highest mean fracture values. Conclusion The shape of a split-file designed all-ceramic reconstruction calls for a different dimension protocol, compared to traditionally shaped ones, as the split-file design leads to sharp approximal indentations acting as fractural impressions, thus decreasing the overall strength. The design of a framework is a crucial factor for the load bearing capacity of an all-ceramic FDP. The state-of-the-art design is preferable since the split-file designed cores call for a cross-sectional connector area at least 42% larger, to have the same load bearing capacity as the state-of-the-art designed cores. All veneering materials and techniques tested in the study, split-file, over-press, built-up porcelains, and glass–ceramics are, with a great safety margin, sufficient for clinical use

  15. Direct Composite Laminate Veneers: Three Case Reports

    PubMed Central

    Korkut, Bora; Yanıkoğlu, Funda; Günday, Mahir

    2013-01-01

    Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolo-rations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here. PMID:23875090

  16. Porcelain laminate veneers: Clinical survey for evaluation of failure

    PubMed Central

    Alhekeir, Diemah F.; Al-Sarhan, Rana A.; Al Mashaan, Abdulmohsen F.

    2014-01-01

    Objective To investigate the association of the failure of porcelain laminate veneers with factors related to the patient, material, and operator. Methods This clinical survey involved 29 patients (19 women and 10 men) and their dentists, including undergraduate and postgraduate dental students and dental interns. Two questionnaires were distributed to collect information from participants. All patients were clinically examined. Criteria for failure of the porcelain laminate veneers included color change, cracking, fracture, and/or debonding. Results A total of 205 porcelain laminate veneers were evaluated. All of the restorations were fabricated from IPS e.max Press and cemented with Variolink Veneer (Ivoclar Vivadent, Schaan, Principality of Liechtenstein) or RelyX veneer cement (3M ESPE, St. Paul, MN, USA). The preparations were generally located in enamel (58.6%), and most veneers had an overlapped design (89.7%). Ten patients (34.48%) showed veneer failure, most often in terms of color change (60%). Overall, 82.8% of patients were satisfied with their restorations. Conclusion Insufficient clinical skills or operator experience resulted in restoration failure in one-third of patients. PMID:25408598

  17. Shear Bond Strengths between Three Different Yttria-Stabilized Zirconia Dental Materials and Veneering Ceramic and Their Susceptibility to Autoclave Induced Low-Temperature Degradation.

    PubMed

    Sehgal, Manoti; Bhargava, Akshay; Gupta, Sharad; Gupta, Prateek

    2016-01-01

    A study was undertaken to evaluate the effect of artificial aging through steam and thermal treatment as influencing the shear bond strength between three different commercially available zirconia core materials, namely, Upcera, Ziecon, and Cercon, layered with VITA VM9 veneering ceramic using Universal Testing Machine. The mode of failure between zirconia and ceramic was further analyzed as adhesive, cohesive, or mixed using stereomicroscope. X-ray diffraction and SEM (scanning electron microscope) analysis were done to estimate the phase transformation (m-phase fraction) and surface grain size of zirconia particles, respectively. The purpose of this study was to simulate the clinical environment by artificial aging through steam and thermal treatment so as the clinical function and nature of the bond between zirconia and veneering material as in a clinical trial of 15 years could be evaluated. PMID:27293439

  18. Shear Bond Strengths between Three Different Yttria-Stabilized Zirconia Dental Materials and Veneering Ceramic and Their Susceptibility to Autoclave Induced Low-Temperature Degradation

    PubMed Central

    Sehgal, Manoti; Bhargava, Akshay; Gupta, Sharad; Gupta, Prateek

    2016-01-01

    A study was undertaken to evaluate the effect of artificial aging through steam and thermal treatment as influencing the shear bond strength between three different commercially available zirconia core materials, namely, Upcera, Ziecon, and Cercon, layered with VITA VM9 veneering ceramic using Universal Testing Machine. The mode of failure between zirconia and ceramic was further analyzed as adhesive, cohesive, or mixed using stereomicroscope. X-ray diffraction and SEM (scanning electron microscope) analysis were done to estimate the phase transformation (m-phase fraction) and surface grain size of zirconia particles, respectively. The purpose of this study was to simulate the clinical environment by artificial aging through steam and thermal treatment so as the clinical function and nature of the bond between zirconia and veneering material as in a clinical trial of 15 years could be evaluated. PMID:27293439

  19. Damage Maps of Veneered Zirconia under Simulated Mastication

    PubMed Central

    Kim, Jae-Won; Kim, Joo-Hyung; Janal, Malvin N.; Zhang, Yu

    2016-01-01

    Zirconia based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesize that veneer chipping/delamination is a result of the propagation of near-contact induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, flat porcelain veneered zirconia plates were cemented to dental composites and cyclically loaded (contact–slide–liftoff) at an inclination angle as a simplified model of zirconia based restorations under occlusion. In the light of in-situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, postmortem damage evaluation of porcelain/zirconia/composite trilayers using a sectioning technique revealed that deep penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed. PMID:19029080

  20. Damage maps of veneered zirconia under simulated mastication.

    PubMed

    Kim, J-W; Kim, J-H; Janal, M N; Zhang, Y

    2008-12-01

    Zirconia-based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesized that veneer chipping/delamination is a result of the propagation of near-contact-induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, we cemented flat porcelain-veneered zirconia plates onto dental composites and cyclically loaded them (contact-slide-liftoff) at an inclination angle as a simplified model of zirconia-based restorations under occlusion. In light of in situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, post mortem damage evaluation of porcelain/zirconia/composite trilayers by a sectioning technique revealed that deep-penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed. PMID:19029080

  1. Ultimate ceramic veneer: a laboratory-guided preparation technique for minimally invasive laminate veneers.

    PubMed

    De Andrade, Oswaldo Scopin; Hirata, Ronaldo; Celestrino, Marcos; Seto, Marcio; Siqueira, Sérgio; Nahas, Rodrigo

    2012-06-01

    Clinical success of ceramic laminate veneers depends on material selection, bonding procedures, controlled laboratory steps, and enamel preservation. Enamel preservation is the most critical because excessive tooth preparation can expose dentin reducing bond strength, which is a factor that can cause a decrease in long-term clinical success. The proposed technique based on carefully treatment planning developed between clinician and dental technician helps to maximize enamel preservation, which is an important element for clinical success. PMID:22856034

  2. Residual Stresses in Porcelain-veneered Zirconia Prostheses

    PubMed Central

    Baldassarri, Marta; Stappert, Christian F. J.; Wolff, Mark S.; Thompson, Van P.; Zhang, Yu

    2012-01-01

    Objectives Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of full-contour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method. Methods Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5 s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n = 4) and porcelain specimens without zirconia cores (monolayers, n = 2). Results The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 ± 12 μm and 52 ± 8 μm for the bilayers and 64 ± 8 μm and 64 ± 7 μm for the monolayers. These results indicated a major hoop compressive stress (~40 to 50 MPa) and a moderate radial tensile stress (~10 MPa) in the bulk of the porcelain veneer. Significance Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contributed to the large clinical chip fractures observed in these prostheses. PMID:22578663

  3. Esthetic, occlusal, and periodontal rehabilitation of anterior teeth with minimum thickness porcelain laminate veneers.

    PubMed

    da Cunha, Leonardo Fernandes; Pedroche, Lorena Oliveira; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

    2014-12-01

    Ceramic veneers of minimum thickness provide satisfactory esthetic outcomes while preserving the dental structure. Dental ceramics can both improve the esthetic appearance and reestablish the strength and function of teeth. In worn anterior teeth, functional surfaces, for example, anterior and lateral guidance, can be restored effectively. The characteristics of dental ceramics, such as color stability and mechanical and optical properties, make this material a good choice for indirect restorations, especially when optimum function and esthetics are required. This clinical report presents an occlusal, periodontal, and restorative solution with minimum thickness glass ceramic veneers for worn anterior teeth with multiple diastemas. PMID:25156092

  4. Fracture mechanics analyses of ceramic/veneer interface under mixed-mode loading.

    PubMed

    Wang, Gaoqi; Zhang, Song; Bian, Cuirong; Kong, Hui

    2014-11-01

    Few studies have focused on the interface fracture performance of zirconia/veneer bilayered structure, which plays an important role in dental all-ceramic restorations. The purpose of this study was to evaluate the fracture mechanics performance of zirconia/veneer interface in a wide range of mode-mixities (at phase angles ranging from 0° to 90°), and to examine the effect of mechanical properties of the materials and the interface on the fracture initiation and crack path of an interfacial crack. A modified sandwich test configuration with an oblique interfacial crack was proposed and calibrated to choose the appropriate geometry dimensions by means of finite element analysis. The specimens with different interface inclination angles were tested to failure under three-point bending configuration. Interface fracture parameters were obtained with finite element analyses. Based on the interfacial fracture mechanics, three fracture criteria for crack kinking were used to predict crack initiation and propagation. In addition, the effects of residual stresses due to coefficient of thermal expansion mismatch between zirconia and veneer on the crack behavior were evaluated. The crack initiation and propagation were well predicted by the three fracture criteria. For specimens at phase angle of 0, the cracks propagated in the interface; whereas for all the other specimens the cracks kinked into the veneer. Compressive residual stresses in the veneer can improve the toughness of the interface structure. The results suggest that, in zirconia/veneer bilayered structure the veneer is weaker than the interface, which can be used to explain the clinical phenomenon that veneer chipping rate is larger than interface delamination rate. Consequently, a veneer material with larger fracture toughness is needed to decrease the failure rate of all-ceramic restorations. And the coefficient of thermal expansion mismatch of the substrates can be larger to produce larger compressive

  5. Planetary science: Ubiquitous late veneer

    NASA Astrophysics Data System (ADS)

    Brenan, James

    2012-09-01

    Iron-loving elements are thought to have been added to Mars, Earth and the Moon after core formation. An analysis of meteorites formed in the first two to three million years of Solar System history suggests that a similar late veneer was added elsewhere too.

  6. Clinical performance of porcelain laminate veneers: outcomes of the aesthetic pre-evaluative temporary (APT) technique.

    PubMed

    Gurel, Galip; Morimoto, Susana; Calamita, Marcelo A; Coachman, Christian; Sesma, Newton

    2012-12-01

    This article evaluates the long-term clinical performance of porcelain laminate veneers bonded to teeth prepared with the use of an additive mock-up and aesthetic pre-evaluative temporary (APT) technique over a 12-year period. Sixty-six patients were restored with 580 porcelain laminate veneers. The technique, used for diagnosis, esthetic design, tooth preparation, and provisional restoration fabrication, was based on the APT protocol. The influence of several factors on the durability of veneers was analyzed according to pre- and postoperative parameters. With utilization of the APT restoration, over 80% of tooth preparations were confined to the dental enamel. Over 12 years, 42 laminate veneers failed, but when the preparations were limited to the enamel, the failure rate resulting from debonding and microleakage decreased to 0%. Porcelain laminate veneers presented a successful clinical performance in terms of marginal adaptation, discoloration, gingival recession, secondary caries, postoperative sensitivity, and satisfaction with restoration shade at the end of 12 years. The APT technique facilitated diagnosis, communication, and preparation, providing predictability for the restorative treatment. Limiting the preparation depth to the enamel surface significantly increases the performance of porcelain laminate veneers. PMID:23057051

  7. Graded Zirconia Glass for Resistance to Veneer Fracture

    PubMed Central

    Zhang, Y.; Kim, J.-W.

    2010-01-01

    Failures of zirconia-based all-ceramic restorations appear to be predominantly chips and fractures in the porcelain veneer, from occlusally induced sliding contact damage. We hypothesized that such failure may be substantially mitigated by controlled grading of the elastic modulus at the ceramic surface. In this study, we fabricated graded structures by infiltrating glass into zirconia plates, resulting in improved aesthetics and diminished modulus at the surfaces. Individual plates were then embedded in epoxy or cemented to dental composites and subjected to single- or multi-cycle sliding contact. Plates of porcelain-veneered zirconia and monolithic zirconia served as controls. Graded zirconia-glass structures exhibited over 3 times better resistance to single-cycle sliding damage than monolithic zirconia and 25 times better than veneered zirconia, and had a fatigue sliding damage resistance comparable with that of monolithic zirconia. These zirconia-glass materials can be engineered in shades from white to yellow, and have potentially better cementation properties than homogeneous zirconia. PMID:20651092

  8. Evaluation of shear bond strength between zirconia core and ceramic veneers fabricated by pressing and layering techniques: In vitro study

    PubMed Central

    Subash, M.; Vijitha, D.; Deb, Saikat; Satish, A.; Mahendirakumar, N.

    2015-01-01

    Statement of Problem: Although ceramic veneered on to zirconia core have been in use for quite some time, information regarding the comparative evaluation of the Shear bond strength of Pressable & Layered ceramic veneered on to zirconia core is limited. Purpose of study: To evaluate the shear bond strength of zirconia core and ceramic veneer fabricated by two different techniques, Layering (Noritake CZR) and Pressing (Noritake, CZR Press). Materials and Method: 20 samples of zirconia blocks were fabricated and the samples were divided into group A & B. Group A - Ceramic Veneered over zirconia core by pressing using Noritake CZR Press. Group B - Ceramic Veneered over zirconia core by layering using Noritake CZR. The veneered specimens were mounted on to the center of a PVC tube using self-cure acrylic resin leaving 3 mm of the veneered surface exposed as cantilever. Using a Universal testing machine the blocks were loaded up to failure. Result: The results were tabulated by using independent samples t-test. The mean shear bond strength for Pressed specimens was 12.458 ± 1.63(S.D) MPa and for layered specimens was 8.458 ± 0.845(S.D) MPa. Conclusion: Pressed specimens performed significantly better than the layered specimen with a P value 0.001. Clinicians and dental laboratory technicians should consider the use of pressed ceramics as an alternative to traditional layering procedures to reduce the chances of chipping or de-lamination of ceramics PMID:26538929

  9. Modified maximum tangential stress criterion for fracture behavior of zirconia/veneer interfaces.

    PubMed

    Mirsayar, M M; Park, P

    2016-06-01

    The veneering porcelain sintered on zirconia is widely used in dental prostheses, but repeated mechanical loadings may cause a fracture such as edge chipping or delamination. In order to predict the crack initiation angle and fracture toughness of zirconia/veneer bi-layered components subjected to mixed mode loadings, the accuracy of a new and traditional fracture criteria are investigated. A modified maximum tangential stress criterion considering the effect of T-stress and critical distance theory is introduced, and compared to three traditional fracture criteria. Comparisons to the recently published fracture test data show that the traditional fracture criteria are not able to properly predict the fracture initiation conditions in zirconia/veneer bi-material joints. The modified maximum tangential stress criterion provides more accurate predictions of the experimental results than the traditional fracture criteria. PMID:26807673

  10. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains

    PubMed Central

    Min, Jie; Zhang, Qianqian; Qiu, Xiaoli; Zhu, Minhao; Yu, Haiyang; Gao, Shanshan

    2015-01-01

    Objectives The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains. Methods Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated. Results The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes. Significance Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings. PMID:26368532

  11. Esthetic Rehabilitation of the Smile with No-Prep Porcelain Laminates and Partial Veneers

    PubMed Central

    Farias-Neto, Arcelino; Gomes, Edna Maria da Cunha Ferreira; Sánchez-Ayala, Alfonso; Sánchez-Ayala, Alejandro; Vilanova, Larissa Soares Reis

    2015-01-01

    Rehabilitation of patients with anterior conoid teeth may present a challenge for the clinician, especially when trying to mimic the nature with composite resins. This clinical report exemplifies how a patient with conoid upper lateral incisors was rehabilitated with minimally invasive adhesive restorations. Following diagnostic wax-up and cosmetic mock-up, no-prep veneers and ceramic fragments (partial veneers) were constructed with feldspathic porcelain. This restorative material presents excellent reproduction of the optical properties of the dental structure, especially at minimal thicknesses. In this paper, the details about the treatment are described. A very pleasing outcome was achieved, confirming that minimally invasive adhesive restorations are an excellent option for situations in which the dental elements are healthy, and can be modified exclusively by adding material and the patient does not want to suffer any wear on the teeth. PMID:26568893

  12. 13. VIEW LOOKING NORTHEAST, SHOWING SHIPPING ROOMS AND VENEER MILL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW LOOKING NORTHEAST, SHOWING SHIPPING ROOMS AND VENEER MILL (AT RIGHT), AND ENGINE ROOM (AT LEFT) - Ichabod T. Williams & Sons Sawmill & Veneer Plant, Roosevelt Avenue at Carteret Avenue, Carteret, Middlesex County, NJ

  13. 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

  14. Rehabilitation of a patient with amelogenesis imperfecta using porcelain veneers and CAD/CAM polymer restorations: A clinical report.

    PubMed

    Saeidi Pour, Reza; Edelhoff, Daniel; Prandtner, Otto; Liebermann, Anja

    2015-01-01

    The complete dental rehabilitation of patients with a vertical dimension loss (VDL) caused by structural enamel deficits associated with amelogenesis imperfecta (AI) represents a difficult challenge for restorative teams. Accurate analysis and treatment planning that includes esthetic and functional evaluations and adequate material selection are important prerequisites for successful results. Long-term provisional restorations play an important role in exploring and elucidating the patients' esthetic demands and functional needs. Restorative treatment options can vary from requiring only oral hygiene instructions to extensive dental restorations that include composite fillings, ceramic veneers, metal-ceramic, or all-ceramic crowns. This case report describes a full-mouth rehabilitation of a patient with amelogenesis imperfecta including the case planning, bite replacement, preparation, and restoration setting steps with an experimental CAD/CAM polymer and porcelain veneers. PMID:26345104

  15. Er:YAG laser debonding of porcelain veneers

    NASA Astrophysics Data System (ADS)

    Buu, Natalie; Morford, Cynthia; Finzen, Frederick; Sharma, Arun; Rechmann, Peter

    2010-02-01

    The removal of porcelain veneers using Er:YAG lasers has not been previously described in the scientific literature. This study was designed to systematically investigate the efficacy of an Er:YAG laser on veneer debonding without damaging the underlying tooth structure, as well as preserving a new or misplaced veneer. Initially, Fourier Transform Infrared Spectroscopy (FTIR) was used on flat porcelain veneer samples (IPS Empress Esthetic; Ivoclar Vivadent, Amherst, NY) to assess which infrared laser wavelengths are transmitted through the veneer. Additionally, FTIR spectra from a veneer bonding cement (RelyX Veneer Cement A1; 3M ESPE, St. Paul, MN) were obtained. While the veneer material showed no characteristic water absorption bands in the FTIR, the bonding cement has a broad H2O/OH absorption band coinciding with the ER:YAG laser emission wavelength. Consequently Er:YAG laser energy transmission through different veneer thicknesses was measured. The porcelain veneers transmitted 11 - 18 % of the incident Er:YAG laser energy depending on their thicknesses (Er:YAG laser: LiteTouch by Syneron; wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 μs at 133 mJ/pulse; straight sapphire tip 1,100 μm diameter; Syneron, Yokneam, Israel). Initial signs of cement ablation occurred at approximately 1.8 - 4.0 J/cm2. This can be achieved by irradiating through the veneer with the fiber tip positioned at a distance of 3-6 mm from the veneer surface, and operating the Er:YAG laser with 133 mJ output energy. All eleven veneers bonded on extracted anterior incisor teeth were easily removed using the Er:YAG laser. The removal occurred without damaging underlying tooth structure as verified by light microscopic investigation (Incident Light Microscope Olympus B 50, Micropublisher RTV 3.3 MP, Image Pro software, Olympus). The debonding mainly occurred at the cement/veneer interface. When the samples were stored in saline solution for 5 days and/or an air-waterspray was

  16. Indirect laminate veneer: a conservative novel approach.

    PubMed

    Prajapati, Paranjay; Sethuraman, Rajesh; Naveen, Y G; Patel, Jayanti R

    2013-01-01

    Various treatment options and materials are available for restoration of an endodontically treated tooth. Laminate veneer is conservative treatment usually employed for aesthetic correction or improvement. The indirect composite is available in a wide range of shades and specific characterisation is easily performed chair side in the operatory area, which makes it a quick procedure and time saving for both the patient and the dentist. The physical properties and optical properties are good enough to use it as indirect restorative material, so in this particular case it was the material of choice for fabrication of laminate veneer on anterior tooth. In this case, the endodontically treated tooth with a fractured incisal edge was restored with indirect composite material. PMID:23975914

  17. Minimally invasive veneers: current state of the art

    PubMed Central

    Vanlıoğlu, Burçin Akoğlu; Kulak-Özkan, Yasemin

    2014-01-01

    Ceramic veneers are considered a conservative solution for patients requiring improvement of the shape, color, or position of their anterior teeth. Ceramic veneers have been extensively and successfully used to mask intrinsic staining, to give the appearance of straightening, and to correct minor malformations of anterior teeth without the removal of substantial amounts of sound tooth substance. The current literature was reviewed to search for the most important parameters determining the long-term success and correct application of ceramic veneers. PMID:25506248

  18. Minimally invasive veneers: current state of the art.

    PubMed

    Vanlıoğlu, Burçin Akoğlu; Kulak-Özkan, Yasemin

    2014-01-01

    Ceramic veneers are considered a conservative solution for patients requiring improvement of the shape, color, or position of their anterior teeth. Ceramic veneers have been extensively and successfully used to mask intrinsic staining, to give the appearance of straightening, and to correct minor malformations of anterior teeth without the removal of substantial amounts of sound tooth substance. The current literature was reviewed to search for the most important parameters determining the long-term success and correct application of ceramic veneers. PMID:25506248

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

    PubMed Central

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

    2013-01-01

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

  20. Stress distribution in bone: single-unit implant prostheses veneered with porcelain or a new composite material.

    PubMed

    Juodzbalys, Gintaras; Kubilius, Ricardas; Eidukynas, Valdas; Raustia, Aune M

    2005-06-01

    The purpose of this study was to simulate dynamic and static occlusal loading on one unit fixed, implant-supported prostheses veneered with porcelain and with GRADIA in a 3-dimensional finite element model of the human mandible to analyze and compare the resultant stresses in the superstructures and in the supporting bone. Calculation and visualization of stress, deformation, and displacement of complex structures under simulated forces were evaluated by finite element analysis (FEA) using ANSYS. The device employed was from the OSTEOFIX Dental Implant System (Oulu, Finland), and the veneering materials used were standard dental porcelain and GC GRADIA (Tokyo, Japan), a new composite material. Two different loading conditions were considered: static and transitional or impact, each delivered in three different directions: horizontal (Fh) at 0 degrees , vertical (Fv) at 90 degrees , and oblique (Fo) at 120 degrees . The proportion of the force: magnitude was fh:fv:fo = 1:3.5:7. A vertical load of 500 N, a horizontal load of 143 N, and an oblique load of 1000 N were applied. The results showed that the highest stresses in the bone-implant interface occurred in the region of cortical bone adjacent to the first thread of implants in all models and varied within 6.5%. Maximum stresses and displacements were higher (7%) in those models with statically loaded implants as compared with those that had been dynamically loading. The direction of loading played a major role in determining stress levels and they varied at up to 85%. It was shown that with dynamic loads, the peak of 1.568 mm was registered in the model with the GRADIA veneering material. This displacement was 6.5% higher than that found with the Vita VMK 68 veneers. These results suggest that the implant superstructure-fixed single crown veneering materials-porcelain and GRADIA played minor influences to the displacements and stresses in the implant supported bone with a 1% variance. One of the reasons for this

  1. Porcelain veneering of titanium--clinical and technical aspects.

    PubMed

    Haag, Per

    2011-01-01

    Gold and other alloys have long been used for the production of crowns and bridges as replacements for damaged or lost teeth. However, doubts have arisen on the suitability of using these materials for dental restorations, as gold has also shown a capacity to cause side-effects such as allergic reactions. This is especially valid for alloys, which during the last decades have been used as porcelain-fused-to metal restorations. This fact has led to an interest in using titanium instead of these alloys. Trials to use titanium for this purpose were initiated in Japan in the early 1980s. Titanium as an unalloyed metal differs in two aspects from the above named alloys: it has a phase transformation at 882 degrees C, which changes its outer and inner properties, and it has an expansion that lies between that of the porcelain types available on the market at the time. In Japan a technique for casting titanium was developed, where the after-treatment of the casting was elaborate, to re-establish the original properties of titanium. The porcelain developed for veneering had shortcomings as the rendering produced a rough surface and non satisfactory esthetics. In Sweden a new concept was introduced in 1989. Here the processing of titanium was performed by industrial methods such as milling, spark erosion and laser welding. The idea behind this was to avoid phase transformation. During the 1990s a number of porcelain products were launched and a vast number of both laboratory and clinical studies were performed and published, with varying results. In the first study of this thesis a prospective clinical trial was performed at a public dental health clinic in Sweden. Twenty-five patients were provided with 40 copings of pure titanium, which were veneered with porcelain. After 2 years 36 of these crowns were evaluated and the patients were also interviewed regarding problems such as shooting pains or difficulties in cleaning around the teeth that were crowned. This evaluation

  2. Biaxial flexural strength of bilayered zirconia using various veneering ceramics

    PubMed Central

    Chantranikul, Natravee

    2015-01-01

    PURPOSE The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics. MATERIALS AND METHODS Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (α=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM. RESULTS It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results. CONCLUSION From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young's modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength. PMID:26576251

  3. Feldspathic veneers: what are their indications?

    PubMed

    McLaren, Edward A; LeSage, Brian

    2011-04-01

    Many different materials and treatment options are available in esthetic and restorative dentistry. Various newer products, such as pressed ceramics, offer enhanced functionality; however, in thinner dimensions, they lack the inherent esthetic beauty of traditional materials such as feldspathic porcelain. As patient demands for better esthetics have increased in recent years, so too has the need for restorative materials that closely mimic the patient's natural dentition. Initially used for the creation of porcelain dentures, feldspathic porcelain has emerged as the premier esthetic material for custom veneer restorations. In recent years, the use of hand-layered powder/liquid feldspathic porcelain has been revived based on its highly esthetic values and little-to-no preparation requirements. By keeping preparation to a minimum, less tooth structure is lost and procedures are much less invasive, which is exactly what patients desire. PMID:21560742

  4. Splinted Porcelain Laminate Veneers With a Natural Tooth Pontic: A Provisional Approach for Conservative and Esthetic Treatment of a Challenging Case.

    PubMed

    Jang, J-H; Lee, S-H; Paek, J; Kim, S-Y

    2015-01-01

    Esthetic rehabilitation of discolored anterior teeth is always a great challenge, especially in the presence of pathology. Fortunately, conservative management in the esthetic zone has become more feasible in compromised cases because of the development of restorative materials and advances in dental adhesives. This report presents a complicated case of a patient with tetracycline-related discoloration, multiple root resorption, and a periapical lesion. Treatment was conservative and used a natural tooth pontic and splinted porcelain laminate veneers. PMID:26332738

  5. Influence of cooling rate on zirconia/veneer interfacial adhesion.

    PubMed

    Göstemeyer, Gerd; Jendras, Michael; Dittmer, Marc P; Bach, Friedrich-Wilhelm; Stiesch, Meike; Kohorst, Philipp

    2010-12-01

    Slow cooling firing schedules have recently been introduced by some manufacturers to reduce chipping complications in zirconia-based core/veneer composites. The aim of this study was to test the hypothesis that these firing schedules may influence the bond strength between the zirconia core and veneering ceramic. Four different veneering ceramics recommended for zirconia (Lava Ceram, Triceram, VM9 and Zirox) were fired onto rectangular shaped Y-TZP specimens (Lava Frame) and cooled using a rapid or a slow cooling rate. The resulting bilayer specimens were notched, loaded in a four-point bending test and load-displacement curves were recorded. The critical load to induce stable crack extension at the core/veneer interface was determined, in order to calculate the strain energy release rate (G, Jm⁻²). Additionally, dilatometric measurements of the veneering ceramics were performed to determine the coefficient of thermal expansion (α, ppm.K⁻¹) between 50 and 450°C (α₁) and in the temperature region above the glass transition temperature (α₂). Discrepancies between α₂ and α₁ (Δα) were calculated. For all core/veneer compositions G values were lower for the slowly cooled specimens than for the rapidly cooled specimens. Significant differences with respect to the firing schedule were found in the Triceram and VM9 groups (P<0.05). The reductions in G values correlated with Δα. The bond strength between the zirconia core and the veneer decreased with the slow cooling rate. These results indicate that slow cooling of zirconia restorations may increase the risk of adhesive delamination failures between the core and veneer. PMID:20601242

  6. Review on antibacterial biocomposites of structural laminated veneer lumber

    PubMed Central

    Chen, Zi-xiang; Lei, Qiong; He, Rui-lin; Zhang, Zhong-feng; Chowdhury, Ahmed Jalal Khan

    2015-01-01

    In this review, the characteristics and applications of structural laminated veneer lumber made from planted forest wood is introduced, and its preparation is explained, including various tree species and slab qualities, treatments for multiple effects and reinforced composites. The relevant factors in the bonding technology and pressing processes as well as the mechanical properties, research direction and application prospects of structural laminated veneer lumber made from planted forest wood are discussed. PMID:26858559

  7. Aesthetic Management of Fluoresced Teeth with Ceramic Veneers and Direct Composite Bonding – An Overview and A Case Presentation

    PubMed Central

    Jhajharia, Kapil; Shah, Harsh Haren; Paliwal, Ashutosh; Parikh, Viral

    2015-01-01

    Tooth discolouration is a common problem and affects people of all ages. Apart from the conventional treatment modalities for the same, newer options are available today with better techniques and materials. The present case report describes a 17-year-old girl who had stained and pitted teeth, attributable to dental fluorosis and she desired aesthetic treatment for the same. The pros and cons of all treatment options were carefully weighed and a multistep treatment process involving ceramic veneers and direct bonding were planned. The execution of the planned treatment yielded a good aesthetic and functional outcome. PMID:26266231

  8. Effect of surface roughness on flexural strength of veneer ceramics.

    PubMed

    Fischer, H; Schäfer, M; Marx, R

    2003-12-01

    The strength of ceramic restorations depends on the occlusal surface roughness of the veneering porcelain, which is influenced by the final preparation. The hypothesis of the study was that roughnesses below a critical microscopic defect size--based only on fracture mechanics considerations--also affect flexural strength. The bending failure stress was evaluated on standard specimens of 4 veneer ceramics with 4 different surfaces of defined roughnesses, respectively. A linear correlation was found between roughness and failure stress. A "roughness-free" failure stress value was predicted for each tested material. This theoretical value can represent the "true" strength of the respective ceramic material. We conclude from our results that the final preparation of a ceramic restoration is critical to the strength of the material, and that ceramic veneering materials can be compared more objectively with respect to their strength by means of roughness-free strength values. PMID:14630897

  9. Lunar tungsten isotopic evidence for the late veneer.

    PubMed

    Kruijer, Thomas S; Kleine, Thorsten; Fischer-Gödde, Mario; Sprung, Peter

    2015-04-23

    According to the most widely accepted theory of lunar origin, a giant impact on the Earth led to the formation of the Moon, and also initiated the final stage of the formation of the Earth's core. Core formation should have removed the highly siderophile elements (HSE) from Earth's primitive mantle (that is, the bulk silicate Earth), yet HSE abundances are higher than expected. One explanation for this overabundance is that a 'late veneer' of primitive material was added to the bulk silicate Earth after the core formed. To test this hypothesis, tungsten isotopes are useful for two reasons: first, because the late veneer material had a different (182)W/(184)W ratio to that of the bulk silicate Earth, and second, proportionally more material was added to the Earth than to the Moon. Thus, if a late veneer did occur, the bulk silicate Earth and the Moon must have different (182)W/(184)W ratios. Moreover, the Moon-forming impact would also have created (182)W differences because the mantle and core material of the impactor with distinct (182)W/(184)W would have mixed with the proto-Earth during the giant impact. However the (182)W/(184)W of the Moon has not been determined precisely enough to identify signatures of a late veneer or the giant impact. Here, using more-precise measurement techniques, we show that the Moon exhibits a (182)W excess of 27 ± 4 parts per million over the present-day bulk silicate Earth. This excess is consistent with the expected (182)W difference resulting from a late veneer with a total mass and composition inferred from HSE systematics. Thus, our data independently show that HSE abundances in the bulk silicate Earth were established after the giant impact and core formation, as predicted by the late veneer hypothesis. But, unexpectedly, we find that before the late veneer, no (182)W anomaly existed between the bulk silicate Earth and the Moon, even though one should have arisen through the giant impact. The origin of the homogeneous (182

  10. Effects of core characters and veneering technique on biaxial flexural strength in porcelain fused to metal and porcelain veneered zirconia

    PubMed Central

    Oh, Ju-Won; Song, Kwang-Yeob; Ahn, Seung-Geun; Park, Ju-Mi; Lee, Min-Ho

    2015-01-01

    PURPOSE The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia. MATERIALS AND METHODS Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgroups with two different veneering methods (conventional powder/liquid layering technique and the heat-pressing technique). Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted. Factors influencing fracture strength were analyzed through three-way ANOVA (α≤.05) and the influence of core thickness and veneering method in each core materials was assessed using two-way ANOVA (α≤.05). RESULTS The biaxial flexural strength test showed that the fabrication method of veneering porcelain has the largest impact on the fracture strength followed by the core thickness and the core material. In the metal groups, both the core thickness and the fabrication method of the veneering porcelain significantly influenced on the fracture strength, while only the fabrication method affected the fracture strength in the zirconia groups. CONCLUSION The fabrication method is more influential to the strength of a prosthesis compared to the core character determined by material and thickness of the core. PMID:26576250

  11. Endo-restorative treatment of a severly discolored upper incisor: resolution of the “aesthetic” problem through Componeer veneering System

    PubMed Central

    Migliau, Guido; Besharat, Laith Konstantinos; Sofan, Afrah Ali Abdullah; Sofan, Eshrak Ali Abdullah; Romeo, Umberto

    2015-01-01

    Summary Aim Re-establishing a patient’s lost dental aesthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct or indirect veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. The aim of the study is to evaluate clinically the effectiveness of a direct composite veneering system in resolving aesthetic problem of an upper incisor with a multidisciplinary treatment approach. Methods Patient with a severe discolored upper incisor came to our attention; at the X-ray exam there was an evidence of a past not good root canal treatment and also old and incongruent composite obturation. After removing all the material inside the root canal was performed a new correct endodontic filling, then Authors tried to bleach the tooth trough “walking-bleach” technique with a hydrogen peroxide (30 volumes) and sodium perborate solution without excellent results. So it was decided to insert a glass-fiber post and than to perform a direct composite veneer with Componeer System (Coltene). Componeer System is a system of prefabricated composite veneers that are abled to be applied directly in the first appointment: after a conservative preparation of the tooth, it must be used an adhesive agent (for example a “three steps”) and then with composite stratification it’s possible to apply the componeer veneer (choosing the right measure, modified as necessary) as the last covering aesthetic layer. Result The evaluation of result of this multidisciplinary treatment was essentially clinical and radiological; in fact it’s possible to observe, from a clinical point of view, the good aesthetic aspect of the direct composite restoration with componeer veneer that offers also some advantages: conservative preparation with

  12. Influence of bruxism on survival of porcelain laminate veneers

    PubMed Central

    Agustín-Panadero, Rubén; Fons-Font, Antonio; Román-Rodríguez, Juan L.; Solá-Ruíz, María F.

    2014-01-01

    Objectives: This study aims to determine whether bruxism and the use of occlusal splints affect the survival of porcelain laminate veneers in patients treated with this technique. Material and Methods: Restorations were made in 70 patients, including 30 patients with some type of parafunctional habit. A total of 323 veneers were placed, 170 in patients with bruxism activity, and the remaining 153 in patients without it. A clinical examination determined the presence or absence of ceramic failure (cracks, fractures and debonding) of the restorations; these incidents were analyzed for association with bruxism and the use of splints. Results: Analysis of the ceramic failures showed that of the 13 fractures and 29 debonding that were present in our study, 8 fractures and 22 debonding were related to the presence of bruxism. Conclusions: Porcelain laminate veneers are a predictable treatment option that provides excellent results, recognizing a higher risk of failure in patients with bruxism activity. The use of occlusal splints reduces the risk of fractures. Key words:Veneer, fracture, debonding, bruxism, occlusal splint. PMID:23986018

  13. Wet-preserved hemp fibreboard properties improvement with veneering

    NASA Astrophysics Data System (ADS)

    Kirilovs, E.; Kukle, S.; Gusovius, H.-J.

    2015-03-01

    The initial research describes a new type of fiber boards for the furniture interior design, developed in cooperation with ATB (Leibniz-Institute for Agricultural Engineering) by using a new method of raw materials preparation and specific production technologies of ATB. The main raw materials are aerobically aged hemp stalks. The samples are made of hemp chips with a long preservation time and fastened together with the UF glue. Specimens are 8 mm thick and correspond to a medium-density fiberboard, fitting standard EN622. Due to the fact that non-veneered material can be used only in non-load-bearing constructions, material improving technologies were studied, such as increase of board density, increase of glue percentage, partially substitution of wet-preserved hemp chips with a dry hemp and/or wooden chips to equalize moisture content of obtained mixture. The particular article describes how the new material is veneered with the oak veneer obtaining three-ply composite board with the improved mechanical properties that allows to use these boards in a load-bearing constructions. Tests are performed with the veneered material to determine such parameters as static bending strength (MOR), modulus of elasticity in static bending (MOE), swelling in thickness and hardness.

  14. Tensile strength of bilayered ceramics and corresponding glass veneers

    PubMed Central

    Champirat, Tharee; Jirajariyavej, Bundhit

    2014-01-01

    PURPOSE To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. MATERIALS AND METHODS Blocks of core ceramics (IPS e.max® Press and Lava™ Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm2 in cross-sectional area (n = 30/group). Additionally, monolithic microbars of these two veneers (IPS e.max® Ceram and Lava™ Ceram; n = 30/group) were also prepared. The obtained microbars were tested in tension until fracture, and the fracture surfaces of the microbars were examined with fluorescent black light and scanning electron microscope (SEM) to identify the mode of failure. One-way ANOVA and the Dunnett's T3 test were performed to determine significant differences of the mean microtensile bond strength at a significance level of 0.05. RESULTS The mean microtensile bond strength of IPS e.max® Press/IPS e.max® Ceram (43.40 ± 5.51 MPa) was significantly greater than that of Lava™ Frame/Lava™ Ceram (31.71 ± 7.03 MPa)(P<.001). Fluorescent black light and SEM analysis showed that most of the tested microbars failed cohesively in the veneer layer. Furthermore, the bond strength of Lava™ Frame/Lava™ Ceram was comparable to the tensile strength of monolithic glass veneer of Lava™ Ceram, while the bond strength of bilayered IPS e.max® Press/IPS e.max® Ceram was significantly greater than tensile strength of monolithic IPS e.max® Ceram. CONCLUSION Because fracture site occurred mostly in the glass veneer and most failures were away from the interfacial zone, microtensile bond test may not be a suitable test for bonding integrity. Fracture mechanics approach such as fracture toughness of the interface may be more appropriate to represent the bonding quality between two materials. PMID:25006377

  15. Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

    PubMed

    Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

    2016-01-01

    The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

  16. The effect of various veneering techniques on the marginal fit of zirconia copings

    PubMed Central

    Torabi, Kianoosh; Vojdani, Mahroo; Giti, Rashin; Pardis, Soheil

    2015-01-01

    PURPOSE This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). MATERIALS AND METHODS Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measured before and after veneering process at 18 sites on the master die using a digital microscope. Paired t-test was used to evaluate mean marginal gap changes. One-way ANOVA and post hoc tests were also employed for comparison among 3 groups (α=.05). RESULTS Marginal gap of 3 groups was increased after porcelain veneering. The mean marginal gap values after veneering in the layering group (63.06 µm) was higher than press-over (50.64 µm) and CAD-on (51.50 µm) veneered groups (P<.001). CONCLUSION Three veneering methods altered the marginal fit of zirconia copings. Conventional layering technique increased the marginal gap of zirconia framework more than pressing and CAD-on techniques. All ceramic crowns made through three different veneering methods revealed clinically acceptable marginal fit. PMID:26140175

  17. Dental Amalgam

    MedlinePlus

    ... Products and Medical Procedures Dental Devices Dental Amalgam Dental Amalgam Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Dental amalgam is a dental filling material which is ...

  18. Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers

    PubMed Central

    Riva, Giancarlo

    2014-01-01

    No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients' restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with laminate nanohybrid resin composite veneers. A step-by-step protocol is proposed for diagnostic evaluation, mock-up fabrication and trial, teeth preparation and impression, and adhesive cementation. The resolution of initial esthetic issues, patient satisfaction, and nice integration of indirect restorations confirmed the success of this anterior dentition rehabilitation. PMID:25013730

  19. Veneer vs. core failure in adhesively bonded all-ceramic crown layers.

    PubMed

    Lee, J J-W; Kwon, J-Y; Bhowmick, S; Lloyd, I K; Rekow, E D; Lawn, B R

    2008-04-01

    Joining a brittle veneer to a strong ceramic core with an adhesive offers potential benefits over current fabrication methods for all-ceramic crowns. We tested the hypothesis that such joining can withstand subsurface radial cracking in the veneer, from enhanced flexure in occlusal loading, as well as in the core. Critical conditions to initiate fractures were investigated in model crown-like layer structures consisting of glass veneers epoxy-joined onto alumina or zirconia cores, all bonded to a dentin-like polymer base. The results showed a competition between critical loads for radial crack initiation in the veneers and cores. Core radial cracking was relatively independent of adhesive thickness. Zirconia cores were much less susceptible to fracture than alumina, attributable to a relatively high strength and low modulus. Veneer cracking did depend on adhesive thickness. However, no significant differences in critical loads for veneer cracking were observed for specimens containing alumina or zirconia cores. PMID:18362320

  20. Bonding a veneered zirconia anterior fixed partial denture.

    PubMed

    Lawson, Nathaniel C; Chavali, Ramakiran; Burgess, John O

    2015-01-01

    This case report documents the rationale and procedure for bonding a veneered zirconia restoration. A three-unit zirconia fixed partial denture (FPD) was fabricated with facial and incisal porcelain veneering. The intaglio surface of the prosthesis was abraded with 50-μm aluminum oxide (Al2O3) particles and coated with one layer of a 10-methacryloxydecyl dihydrogen phosphate (MDP) primer. The FPD was tried into the mouth and occlusal adjustment was performed with a fine grit diamond, and then it was polished with zirconia polishing points. The intaglio surfaces of the abutment crowns were cleaned with 37% phosphoric acid and rinsed. A self-etch adhesive was applied to the tooth preparations and light-cured, and the crowns were filled with cement and seated. Excess cement was immediately wiped away with a brush, followed by spot-curing of the margins. The case demonstrates that, when properly designed, veneered zirconia restorations offer acceptable esthetic and mechanical properties for anterior FPDs. PMID:25822406

  1. Joining Dental Ceramic Layers With Glass

    PubMed Central

    Saied, MA; Lloyd, IK; Haller, WK; Lawn, BR

    2011-01-01

    Objective Test the hypothesis that glass-bonding of free-form veneer and core ceramic layers can produce robust interfaces, chemically durable and aesthetic in appearance and, above all, resistant to delamination. Methods Layers of independently produced porcelains (NobelRondo™ Press porcelain, Nobel BioCare AB and Sagkura Interaction porcelain, Elephant Dental) and matching alumina or zirconia core ceramics (Procera alumina, Nobel BioCare AB, BioZyram yttria stabilized tetragonal zirconia polycrystal, Cyrtina Dental) were joined with designed glasses, tailored to match thermal expansion coefficients of the components and free of toxic elements. Scanning electron microprobe analysis was used to characterize the chemistry of the joined interfaces, specifically to confirm interdiffusion of ions. Vickers indentations were used to drive controlled corner cracks into the glass interlayers to evaluate the toughness of the interfaces. Results The glass-bonded interfaces were found to have robust integrity relative to interfaces fused without glass, or those fused with a resin-based adhesive. Significance The structural integrity of the interfaces between porcelain veneers and alumina or zirconia cores is a critical factor in the longevity of all-ceramic dental crowns and fixed dental prostheses. PMID:21802131

  2. Effect of Provisional Cements on Shear Bond Strength of Porcelain Laminate Veneers

    PubMed Central

    Altintas, Subutay Han; Tak, Onjen; Secilmis, Asli; Usumez, Aslihan

    2011-01-01

    Objectives: The purpose of this study was to evaluate the effect of three provisional cements and two cleaning techniques on the final bond strength of porcelain laminate veneers. Methods: The occlusal third of the crowns of forty molar teeth were sectioned and embedded in autopolymerizing acrylic resin. Dentin surfaces were polished and specimens were randomly divided into four groups (n=10). Provisional restorations were fabricated and two provisional restorations were cemented onto each tooth. Restorations were fixed with one of three different provisional cements: eugenol-free provisional cement (Cavex), calcium hydroxide (Dycal), and light-cured provisional cement (Tempond Clear). Provisional restorations were removed with either a dental explorer and air-water spray, or a cleaning bur (Opticlean). In the control group, provisional restorations were not used on the surfaces of specimens. IPS Empress 2 ceramic discs were luted with a dual-cured resin cement (Panavia F). Shear bond strength was measured using a universal testing machine. Data were statistically analyzed by ANOVA, Tukey’s HSD and Dunnett tests. Surfaces were examined by scanning electronic microscopy. Results: Significant differences were found between the control group and both the light-cured provisional cement groups and the eugenol-free provisional cement-cleaning bur group (P<.05). Groups that had received light-cured provisional cement showed the lowest bond strength values. Conclusions: Selection of the provisional cement is an important factor in the ultimate bond strength of the final restoration. Calcium hydroxide provisional cement and cleaning with a dental explorer are advisable. PMID:21912495

  3. Application of Monolithic Zirconia Ceramics in Dental Practice: A Case History Report.

    PubMed

    Kim, Hee-Kyung; Kim, Sung-Hun; Lee, Jai-Bong; Han, Jung-Suk; Yeo, In-Sung

    2016-01-01

    Monolithic zirconia restorations increasingly have been used in dental practice in recent years and demonstrate superior mechanical performance compared with porcelain-veneered zirconia restorations. Recent advances in manufacturing technology have made possible the fabrication of translucent monolithic zirconia ceramics. This case report describes three clinical examples of monolithic zirconia fixed dental prostheses being used in the anterior and posterior regions and exhibiting acceptable esthetic results. PMID:27611758

  4. 40 CFR 63.2265 - Initial compliance demonstration for a softwood veneer dryer.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Initial compliance demonstration for a softwood veneer dryer. 63.2265 Section 63.2265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... you operate a softwood veneer dryer, you must develop a plan for review and approval for...

  5. 40 CFR 63.2265 - Initial compliance demonstration for a softwood veneer dryer.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 12 2011-07-01 2009-07-01 true Initial compliance demonstration for a softwood veneer dryer. 63.2265 Section 63.2265 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... you operate a softwood veneer dryer, you must develop a plan for review and approval for...

  6. A photoelastic assessment of residual stresses in zirconia-veneer crowns.

    PubMed

    Belli, R; Monteiro, S; Baratieri, L N; Katte, H; Petschelt, A; Lohbauer, U

    2012-03-01

    Residual stresses within the veneer are linked to the high prevalence of veneer chipping observed in clinical trials of zirconia prostheses. We hypothesized that the thermal mismatch between the zirconia infrastructure and the veneer porcelain, as well as the rate used for cooling zirconia-veneer crowns, would be directly proportional to the magnitude of residual stresses built within the veneer layer. Two porcelains with different coefficients of thermal expansion were used to veneer zirconia copings, to create high or low thermal mismatches. The crowns were cooled according to a fast- or a slow-cooling protocol. The retardation of polarized light waves was used to calculate the residual stress magnitude and distribution across the veneer, according to the photoelasticity principle, in 1.0-mm-thick crown sections. While thermal mismatch was an important factor influencing the maximum stress development in the veneer, cooling rate had a minor role. Curved surfaces were preferential sites for stress concentration regardless of thermal mismatch or cooling rate. PMID:22262632

  7. Origin and mixing timescale of Earth's late veneer

    NASA Astrophysics Data System (ADS)

    Prescher, C.; Allu Peddinti, D.; Bell, E. A.; Bello, L.; Cernok, A.; Ghosh, N.; Tucker, J.; Wielicki, M. M.; Zahnle, K. J.

    2012-12-01

    Experimental studies on the partitioning behavior of highly siderophile elements (HSE) between silicate and metallic melts imply that the Earth's mantle should have been highly depleted in these elements by core formation in an early magma ocean. However, present HSE contents of the Earth's mantle are ~3 orders of magnitude higher than that expected by experiments. The apparent over-abundance of HSE has commonly been explained by the addition of meteoritic material in the "late veneer" which describes the exogenous mass addition following the moon forming impact and concluding with the late heavy bombardment at ~3.8-3.9 Ga. The strongest evidence for this theory is that the platinum group element (PGE) contents in today's mantle are present in chondritic relative abundances, as opposed to a fractionated pattern expected with metal-silicate partitioning. Archean komatiites indicate that the PGE content of the Earth's mantle increased from about half their present abundances at 3.5 Ga to their present abundances at 2.9 Ga. This secular increase in PGE content suggests a progressive mixing of the late veneer material into the Earth's mantle. However, this time scale also implies that the whole mantle was relatively well mixed by 2.9 Ga. We use a compilation of existing isotopic and trace element data in order to constrain the origin and composition of the late veneer. We use PGE abundances, W abundances and W isotopic compositions in chondritic meteorites and the primitive upper mantle to compute the amount of mass delivered during the late veneer and find the late veneer mass to be ~0.6 % the mass of the bulk silicate Earth (consistent with earlier estimates). We also use the 187Re-187Os and 190Pt-186Os systems to constrain the composition and timing of delivery of the impacting population. We model the efficiency of mantle mixing in this time frame by using 3-dimensional numerical geodynamical simulations and geochemical constraints. Initial parameters include the

  8. Reliability and fatigue failure modes of implant-supported aluminum-oxide fixed dental prostheses

    PubMed Central

    Stappert, Christian F. J.; Baldassarri, Marta; Zhang, Yu; Hänssler, Felix; Rekow, Elizabeth D.; Thompson, Van P.

    2012-01-01

    Objectives To investigate failure modes and reliability of implant-supported aluminum-oxide three-unit fixed-dental-prostheses (FDPs) using two different veneering porcelains. Material and methods Thirty-six aluminum-oxide FDP-frameworks were CAD/CAM fabricated and either hand-veneered(n=18) or over-pressed(n=18). All FDPs were adhesively luted to custom-made zirconium-oxide-abutments attached to dental implant fixtures (RP-4×13mm). Specimens were stored in water prior to mechanical testing. A Step-Stress-Accelerated-Life-Test (SSALT) with three load/cycles varying profiles was developed based on initial single-load-to-failure testing. Failure was defined by veneer chipping or chipping in combination with framework fracture. SSALT was performed on each FDP inclined 30° with respect to the applied load direction. For all specimens, failure modes were analyzed using polarized-reflected-light-microscopy and scanning-electron-microscopy (SEM). Reliability was computed using Weibull analysis software (Reliasoft). Results The dominant failure mode for the over-pressed FDPs was buccal chipping of the porcelain in the loading area of the pontic, while hand-veneered specimens failed mainly by combined failure modes in the veneering porcelain, framework and abutments. Chipping of the porcelain occurred earlier in the over-pressed specimens (350 N/85k, load/cycles) than in the hand-veneered (600 N/110k)(profile I). Given a mission at 300 N load and 100k or 200 K cycles the computed Weibull reliability (2-sided at 90.0 % confidence bounds) was 0.99(1/0.98) and 0.99(1/0.98) for hand-veneered FDPs, and 0.45(0.76/0.10) and 0.05(0.63/0) for over-pressed FDPs, respectively. Conclusions In the range of average clinical loads (300–700 N), hand-veneered aluminum-oxide FDPs showed significantly less failure by chipping of the veneer than the over-pressed. Hand-veneered FDPs under fatigue loading failed at loads ≥ 600N. PMID:22093019

  9. [Different types of tooth preparation for placement of ceramic veneers].

    PubMed

    Fernández Bodereau, E

    1989-09-01

    Lately the porcelain laminate veneer in the fore-upper sector of the mouth, has gained popularity due to the multiple advantages that it has shown, therefrom the purpose of describing the different reduction techniques according to the function of the laminate restauration. We describe the instruments that will be used and the sequence that should be carried on during the different types of reduction, classifying them in three large groups according to the anomaly presented by the elements to be restored. PMID:2639346

  10. Predictable Outcomes with Porcelain Laminate Veneers: A Clinical Report.

    PubMed

    Pimentel, Welson; Teixeira, Marcelo Lucchesi; Costa, Priscila Paganini; Jorge, Mônica Zacharias; Tiossi, Rodrigo

    2016-06-01

    This clinical report describes how to achieve predictable outcomes for anterior teeth esthetic restorations with porcelain laminate veneers by associating the digital planning and design of the restoration with interim restorations. The previous digital smile design of the restoration eliminates the communication barrier with the patient and assists the clinician throughout patient treatment. Interim restorations (diagnostic mock-ups) further enhance communication with the patient and prevent unnecessary tooth reduction for conservative tooth preparation. Adequate communication between patient and clinician contributes to successful definitive restorations and patient satisfaction with the final esthetic outcome. PMID:26633080

  11. Interfacial adhesion of zirconia/veneer bilayers with different thermal characteristics.

    PubMed

    Freifrau Von Maltzahn, Nadine; Kleibe, Martin; Stiesch, Meike; Hübsch, Christoph; Kohorst, Philipp

    2014-01-01

    The aim of this study was to investigate how changes in the thermal characteristics of veneer ceramics with almost identical chemical and mechanical properties but with different coefficients of thermal expansion (CTE) can modify their interfacial adhesion to zirconia. 48 bilayers made of one Y-TZP ceramic and four veneer ceramics were fabricated (n=12). Thermal residual stresses were calculated on the basis of the CTE and glass transition temperatures. After defined notching all specimens were loaded in a four-point bending test and the critical loads were recorded which induced stable crack extension at the adhesion interface. The strain energy release rate (G, J/m(2)) was calculated and was taken as a measure of interfacial adhesion. The CTE of the veneer ceramics were significantly correlated with their adhesion to Y-TZP (p<0.001). Interfacial adhesion in zirconia/veneer bilayers is predominantly affected by the thermal characteristics of the veneer ceramic. PMID:24786347

  12. Influence of surface treatment on bond strength of veneering ceramics fused to zirconia.

    PubMed

    Tada, Kouki; Sato, Toru; Yoshinari, Masao

    2012-01-01

    In all-ceramic restorations involving a zirconia framework, surface treatment of the zirconia surface is required to enhance bonding strength with the veneering ceramics and thus prevent chipping. The purpose of the present study was to investigate the influence of surface roughness and heat treatment of the zirconia and use of liner porcelain on bond strength between veneering ceramics and a zirconia framework. Debonding/crack-initiation strength (τb) was determined according to ISO 9693. No significant difference was observed among conditions, except with use of a liner under heat treatment, which yielded a τb of 26.0±2.9-28.9±1.7 MPa. Electron probe microanalysis revealed that components of the veneering ceramics remained on the zirconia surface after debonding, suggesting that fractures occur in the veneering ceramics and that improving the strength of the veneering ceramics themselves might increase bond strength. PMID:22447064

  13. Influence of silane surface modification of veneer on interfacial adhesion of wood-plastic plywood

    NASA Astrophysics Data System (ADS)

    Fang, Lu; Chang, Liang; Guo, Wen-jing; Chen, Yongping; Wang, Zheng

    2014-01-01

    In this study, wood-plastic plywood was fabricated with high density polyethylene (HDPE) film and poplar veneer by hot-pressing. To improve the interfacial adhesion between the wood veneer and HDPE film, silane A-171 (vinyltrimethoxysilane) was used to treat the surface of poplar veneer by spraying. The effects of silane agent on the veneer surface properties as well as the physical-mechanical performance of wood-plastic plywood were evaluated. The adsorption of several prehydrolyzed alkoxysilanes onto the veneer surface and the existence of a covalent bonding between the wood veneer and silane agent were confirmed using FTIR, XPS and contact angle. Silane surface treatment resulted in enhancement of shear strength and water resistance. When one layer HDPE film was used as adhesive, it caused 293.2% increase in shear strength, 34.6% and 40.8% reduction in water absorption and thickness swelling, respectively. In addition, the wood failure also increased from 5% to 100% due to the silane modification. Dynamic mechanical analysis (DMA) results showed that treated plywood have higher storage modulus, lower tan δ peak value and lagged temperature for tan δ peak value with respect to untreated plywood. Experimental results of interfacial morphology by SEM further revealed better interaction between silane A-171 treated veneer and HDPE film.

  14. Experimental Design on Laminated Veneer Lumber Fiber Composite: Surface Enhancement

    NASA Astrophysics Data System (ADS)

    Meekum, U.; Mingmongkol, Y.

    2010-06-01

    Thick laminate veneer lumber(LVL) fibre reinforced composites were constructed from the alternated perpendicularly arrayed of peeled rubber woods. Glass woven was laid in between the layers. Native golden teak veneers were used as faces. In house formulae epoxy was employed as wood adhesive. The hand lay-up laminate was cured at 150° C for 45 mins. The cut specimen was post cured at 80° C for at least 5 hours. The 2k factorial design of experimental(DOE) was used to verify the parameters. Three parameters by mean of silane content in epoxy formulation(A), smoke treatment of rubber wood surface(B) and anti-termite application(C) on the wood surface were analysed. Both low and high levels were further subcategorised into 2 sub-levels. Flexural properties were the main respond obtained. ANOVA analysis of the Pareto chart was engaged. The main effect plot was also testified. The results showed that the interaction between silane quantity and termite treatment is negative effect at high level(AC+). Vice versa, the interaction between silane and smoke treatment was positive significant effect at high level(AB+). According to this research work, the optimal setting to improve the surface adhesion and hence flexural properties enhancement were high level of silane quantity, 15% by weight, high level of smoked wood layers, 8 out of 14 layers, and low anti termite applied wood. The further testes also revealed that the LVL composite had superior properties that the solid woods but slightly inferior in flexibility. The screw withdrawn strength of LVL showed the higher figure than solid wood. It is also better resistance to moisture and termite attack than the rubber wood.

  15. Dental Sealants

    MedlinePlus

    ... Data & Statistics > Find Data by Topic > Dental Sealants Dental Sealants Main Content Dental sealants are thin plastic coatings that protect the chewing surfaces of children’s back teeth from tooth decay. Overall, the prevalence of sealants ...

  16. 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

  17. 40 CFR 429.30 - Applicability; description of the veneer subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to waters of the United States and to the introduction of process wastewater pollutants into publicly owned treatment works from any plant which manufactures veneer and does not store or hold raw...

  18. Comparison of edge chipping resistance of PFM and veneered zirconia specimens

    PubMed Central

    Quinn, Janet B.; Sundar, Veeraraghavan; Parry, Edward E.; Quinn, George D.

    2011-01-01

    Objectives To investigate the chipping resistance of veneered zirconia specimens and compare it to the chipping resistance of porcelain fused to metal (PFM) specimens. Methods Veneered zirconia and PFM bar specimens were prepared in clinically relevant thicknesses. The specimen edges were chipped with different magnitude forces, producing chips of various sizes. The range of sizes included small chips that did not penetrate all the way through the veneers to the substrates, and also chips that were very large and reached the zirconia or metal substrates. The relationship between force magnitude and chip size (edge distance) was graphed. The resulting curves were compared for the veneered zirconia and PFM specimens. Knoop hardness vs. force graphs for the veneers and substrates were also obtained. Results The zirconia and PFM veneer chipping data followed a power law (coefficient of determination, R2 > 0.93) as expected from the literature. The curves overlapped within the combined data scatter, indicating similar resistance to chipping. The chips made in both types of specimens detached and did not penetrate into the substrate when they reached the veneer/substrate intersections. The hardness–load curves for the veneers and substrates all exhibited an indentation size effect (ISE) at low loads. The Knoop hardness values with uncertainties of ±one standard deviation at 4 N loads for the metal, zirconia, and the metal and zirconia veneers are: (2.02 ± 0.08, 12.01 ± 0.39, 4.24 ± 0.16 and 4.36 ± 0.02 GPa), respectively, with no statistically significant difference between the veneers (Tukey pairwise comparison at 0.95 family confidence). Significance This work indicates that a similar resistance to chipping might be expected for veneered zirconia and PFM restorations, in spite of the large difference in substrate hardness. Differences in susceptibility to chip spalling were not detected, but the chips in both specimen types detached off the sides in a similar

  19. Dental Procedures.

    PubMed

    Ramponi, Denise R

    2016-01-01

    Dental problems are a common complaint in emergency departments in the United States. There are a wide variety of dental issues addressed in emergency department visits such as dental caries, loose teeth, dental trauma, gingival infections, and dry socket syndrome. Review of the most common dental blocks and dental procedures will allow the practitioner the opportunity to make the patient more comfortable and reduce the amount of analgesia the patient will need upon discharge. Familiarity with the dental equipment, tooth, and mouth anatomy will help prepare the practitioner for to perform these dental procedures. PMID:27482994

  20. In vitro evaluation of fracture strength of zirconia restoration veneered with various ceramic materials

    PubMed Central

    Choi, Yu-Sung; Lee, Jai-Bong; Han, Jung-Suk; Yeo, In-Sung

    2012-01-01

    PURPOSE Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques. MATERIALS AND METHODS A 1.2 mm, 360° chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely X™ Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (α=0.05). Scanning electron microscope was used to investigate the fractured interface. RESULTS Mean fracture load and standard deviation was 4263.8±1110.8 N for Group LT, 5070.8±1016.4 for Group HT and 6242.0±1759.5 N for Group ST. The values of Group ST were significantly higher than those of the other groups. CONCLUSION Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength. PMID:22977725

  1. Comparative evaluation of shear bond strengths of veneering porcelain to base metal alloy and zirconia substructures before and after aging – An in vitro study

    PubMed Central

    Sreekala, Laju; Narayanan, Mahesh; Eerali, Sunil M.; Eerali, Susil M.; Varghese, Joju; Zainaba Fathima, A. l.

    2015-01-01

    Objective: The aim of this study was to evaluate and compare the shear bond strength of veneering porcelain to base metal alloy and zirconia substructures before and after aging. Scanning electron microscopy (SEM) was used to determine the failure pattern. Materials and Methods: Twenty rectangular blocks (9 mm length × 4 mm height × 4 mm width) of base metal alloy (Bellabond plus, Bego, Germany) and zirconia (Will ceramZ zirconia K block) were fabricated for shear bond strength test. Surface of the base metal alloy block (4 mm × 4 mm area) was veneered with corresponding veneering porcelain (Ivoclar, IPS classic, vivadent). Similarly, surface of the zirconia rectangular block (4 mm × 4 mm) was veneered with corresponding veneering ceramic (Cercon ceram kiss, Degudent). Out of forty rectangular porcelain veneered core specimen, ten porcelain veneered base metal alloy specimen and ten porcelain veneered zirconia specimen were immersed in water at 37°C for one month to simulate the oral environment. Results: On comparison, the highest shear bond strength value was obtained in porcelain veneered base metal alloy before aging group followed by porcelain veneered base metal alloy after aging group, Porcelain veneered zirconia before aging group, porcelain veneered zirconia after aging group. SEM analysis revealed predominantly cohesive failure of veneering ceramic in all groups. Conclusion: Porcelain veneered base metal alloy samples showed highest shear bond strength than porcelain veneered zirconia samples. Study concluded that aging had an influence on shear bond strength. Shear bond strength was found to be decreasing after aging. SEM analysis revealed cohesive failure of veneering ceramic in all groups suggestive of higher bond strength of the interface than cohesive strength of ceramic. Hence, it was concluded that veneering ceramic was the weakest link. PMID:26942121

  2. Influence of Heat Treatment and Veneering on the Storage Modulus and Surface of Zirconia Ceramic

    PubMed Central

    Siavikis, Georgius; Behr, Michael; van der Zel, Jef M; Feilzer, Albert J; Rosentritt, Martin

    2011-01-01

    Objectives: Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of zirconia. Methods: Zirconia bars (Cercon, DeguDent, G; 0.5x2x20 mm) were fabricated and treated according to veneering conditions. Besides heating regimes between 680°C and 1000°C (liner bake and annealing), sandblasting (Al2O3) or steam cleaning were used. The bars were investigated after 90 days storage in water and acid. For investigating the influence of veneering, the bars were veneered in press- or layer technique. Dynamic mechanical analysis (DMA) in a three-point-bending design was performed to determine the storage modulus between 25°C and 200°C at a frequency of 1.66 Hz. All specimens were loaded on top and bottom (treatment on pressure or tensile stress side). Scanning electron microscopy (SEM) was used for evaluating the superficial changes of the zirconia surface due to treatment. Statistical analysis was performed using Mann Whitney U-test (α=0.05). Results: Sintered zirconia provided a storage modulus E’ of 215 (203/219) GPa and tan δ of 0.04 at 110°C. A 10%-decrease of E’ was found up to 180°C. The superficial appearance changed due to heating regime. Sandblasting reduced E’ to 213 GPa, heating influenced E’ between 205 GPa (liner bake 1) and 222 GPa (dentin bake 1). Steam cleaning, annealing and storage changed E’ between 4 GPa and 22 GPa, depending on the side of loading. After veneering, strong E’-reduction was found down to 84 GPa and 125 GPa. Conclusions: Veneering of zirconia with glass-ceramic in contrast to heat treating during veneering procedure had a strong influence on the modulus. The application of the glass-ceramic caused a stronger decrease of the storage modulus. PMID:21494388

  3. Treatment of natural wood veneers with nano-oxides to improve their fire behaviour

    NASA Astrophysics Data System (ADS)

    Francés Bueno, A. B.; Navarro Bañón, M. V.; Martínez de Morentín, L.; Moratalla García, J.

    2014-08-01

    Conventional flame retardants used to improve fire behaviour of wood based materials are commonly based on halogenated and/or nitrogenated chemicals. These chemicals are toxic and can harm the environment and human health. Some works describe the incorporation of nanomaterials to the polymeric systems to improve their fire behaviour. The aim of this work was to analyze the effect of several treatments based on the use of nanomaterials on the properties of natural wood veneers and mainly on their fire behaviour. Firstly, several modes for treating pine veneers (immersion, spraying and impregnation) were evaluated using a commercial flame retardant to select the most effective treatment. The treatment selected as the most effective was immersion in a bath of flame retarding agent for 30 minutes at standard conditions. Afterward, pine veneers were treated by immersion in aqueous dispersions which contained 3wt% of the following nanoparticles: SiO2, TiO2 and ZrO2, respectively. The effect of each treatment on the properties of veneers was analyzed. The results obtained showed that the treatment based on the use of 3wt% SiO2 aqueous dispersion was the most effective to improve the fire behaviour of pine veneers.

  4. Critical appraisal: clinical considerations for restoring mandibular incisors with porcelain laminate veneers.

    PubMed

    Walter, Robert D; Raigrodski, Ariel J

    2008-01-01

    Porcelain laminate veneers have been proven to be a successful treatment modality for maxillary incisors in clinical practice and in controlled clinical studies. However, the data in clinical studies on the success of veneers for restoring mandibular incisors are limited. Clinically, the successful restoration of mandibular incisors with porcelain laminate veneers is one of the more challenging procedures in all of esthetic restorative dentistry. Limited coronal dimensions, the small amount of enamel available for bonding (particularly in the cervical areas), materials and techniques for the bonding procedures, and the response of the tooth-veneer complex to forces generated during the incisal loading in both functional as well as parafunctional contacts must be considered as potential sources of success or failure. This Critical Appraisal reviews three recent scientific articles to shed some light on these issues and, as in all research endeavors, leads the reader to identify additional areas of concern that might stimulate further scientific inquiry. The first publication studied predictors for enamel thickness for mandibular incisors. The second examined bonding protocols for exposed dentin and suggested immediate dentin sealing. The third paper addressed fracture behavior of mandibular incisors restored with porcelain laminate veneers in vitro. PMID:18768002

  5. Marginal adaptation of Spinell InCeram and feldspathic porcelain laminate veneers

    PubMed Central

    Ghaffari, Tahereh; Hamedi-Rad, Fahimeh; Fakhrzadeh, Vahid

    2016-01-01

    Background: This in vitro study investigated the marginal fit of two porcelain laminate veneers to help the selection of more accurate veneers in discolored teeth. Materials and Methods: Thirty impressions of metal master die created from the prepared labial surface of an acrylic maxillary central incisor were made and poured with Type IV stone. The dies were distributed into test groups (n = 15) for the construction of DuCeram and InCeram laminate veneers. An image-analysis program was used to measure the gap between the veneers and the master die at the labial, lingual, and proximal margins. Statistical analysis was performed with repeated measures ANOVA. Independent t-test was used to compare the mean values between the two groups. Values of P < 0.05 were judged to be significant. Results: Differences between marginal fit of two groups were significant (P < 0.001). The overall mean marginal gap values (μm) for InCeram and DuCeram were, respectively, 114.4 ± 40.81 and 282.3 ± 82.82. Independent t-test revealed significant differences between the marginal gaps of two materials at different predetermined points. Conclusion: Within the limitations of this study, the marginal gap in InCeram laminate veneer was within the clinically acceptable standard set at 120 μm. PMID:27274344

  6. Cyclic testing of porcelain laminiate veneers on superficial enamel and dentin: Pressed vs. conventional layered porcelain

    NASA Astrophysics Data System (ADS)

    Tawde, Shweta

    Statement of Problem: Clinicians are inclined towards more aggressive teeth preparations to accommodate the thickness of the veneering material. The principle of conservative tooth preparation is compromised. Purpose: By using a conservative approach to treatment with porcelain veneers, long-lasting, esthetic and functional results may be achieved. Sacrificing as little tooth structure as possible and conserving the supporting tissues will facilitate prospective patients. Materials and Methods: Forty extracted human maxillary and mandibular canines were selected. The teeth were divided into one of two groups (pressable and stackable) and further subdivided according to tooth substrate (all-enamel or mixed enamel-dentin exposure). Twenty canine teeth were allotted to the pressable veneer group and 20 were allotted to the stackable veneer group. Of the 20 teeth in the pressable group, all were pressed with a lithium disilicate ceramic system (IPS e.max Press), 10 with labial tooth reduction of 0.3-0.5 mm maintaining superficial enamel (PEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (PDN). Of the 20 teeth in the stackable group, all were stacked/ layered with conventional feldspathic porcelain (Fortune; Williams/ Ivoclar); with labial veneer reduction of 0.3-0.5 mm maintaining superficial enamel (SEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (SDN). Silicon putty matrix was fabricated prior to teeth preparation to estimate the teeth reduction. The prepared facial reduction was limited to the incisal edge. No incisal or palatal/lingual reduction was performed. Impressions of the prepared teeth were taken in medium/light-bodied PVS. Master casts were made in Resin Rock. The stackable group specimens were made with fabricating refractory dies and after following the recommended steps of laboratory procedure, stackable veneers were processed. The pressable group

  7. [Assessment of the amount of palladium-silver alloy used for cast posts and veneer crowns].

    PubMed

    Catović, A; Baucić, I

    1988-01-01

    Average amounts of palladium-silver alloy were assessed in a sample of 966 veneer crowns and 667 casted posts. The mean weight values of the samples under study were compared in relation to particular types of anterior teeth. The specimens cast in Auropal SE were weight by the precise balance, Tehtnica, type 6215. Results were analyzed by weight according to the type of the sample under study, and classified according to age, and to the anterior teeth of the upper and lower jaws. On an average, the heaviest posts and veneer crowns were measured on upper canines, whereas the lighest were those on lower incisors. A cast post was found to be by about 40% heavier than a veneer crown on the same tooth. PMID:3076349

  8. Dental Hygienists

    MedlinePlus

    ... anatomy, patient management, and periodontics, which is the study of gum disease. High school students interested in becoming dental hygienists should take courses in biology, chemistry, and math. Most dental hygiene programs also require applicants to have completed at ...

  9. Dental sealants

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000779.htm Dental sealants To use the sharing features on this ... case a sealant needs to be replaced. How Dental Sealants Are Applied Your dentist applies sealants on ...

  10. How will surface treatments affect the translucency of porcelain laminate veneers?

    PubMed Central

    Turgut, Sedanur; Ayaz, Elif Aydogan; Korkmaz, Fatih Mehmet; Ulusoy, Kıvanç Utku; Bagis, Yildirim Hakan

    2014-01-01

    PURPOSE The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. MATERIALS AND METHODS A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 50-µm Al2O3; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (α=0.05). RESULTS There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). CONCLUSION The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values. PMID:24605200

  11. Some important physical properties of laminated veneer lumber (Lvl) made from oriental beech and Lombardy poplar

    NASA Astrophysics Data System (ADS)

    Kılıç, Murat

    2012-09-01

    This study examined some physical characteristics of laminated veneer lumber (LVL) obtained in different compositions from cut veneers of Oriental beech (Fagus Orientalis Lipsky) and Lombardy poplar (Populus nigra) with thicknesses of 4 mm and 5 mm. Five each beech and poplar trees were felled with this objective. The PVAc (Kleiberit 303) and PU (Bizon Timber PU-Max Express) types of adhesive were used in lamination. The air-dry and oven dry densities, cell wall density and porosity, the value of volume density, shrinkage in a tangential and radial direction and volume swelling amounts were determined by preparing the specimens in accordance with the standards.

  12. Spectrophotometric Study of the Effect of Luting Agents on the Resultant Shade of Ceramic Veneers: An Invitro Study

    PubMed Central

    Kale, Yogesh; Pustake, Swati; Bijjaragi, Shobha; Pustake, Bhushan

    2015-01-01

    Introduction Dentistry has found practically the best available aesthetic answer, is ceramic restoration. There are various factors that contribute to the success of ceramic veneers, like colour of underlying tooth, thickness if ceramics and the type of underlying luting cement. Shade selection and matching remains still challenge, however the shade of luting agent used for cementation of veneers produces a change in resultant shade of veneers. Aim To compare and analyze the spectrophotometric effect of opaque and transparent luting agent on resultant shade of ceramic veneers made of 2L1.5 shade (Vitapan 3D-Masters) and B2 shade (Vitapan Classic). Materials and Methods Out of 15 ceramic veneers of 2L1.5 shade (VITAPAN 3D- Master), seven teeth cemented with opaque cement and eight teeth with transparent cement shade of dual cure resin cement (Variolink IITM). Out of 10 ceramic veneers of B2 shade (VITAPAN Classic), five teeth were cemented with opaque cement and other five teeth with transparent cement shade of dual cure resin cement (Variolink IITM). Spectrophotometric (Macbeth U.S.A.) analysis of all ceramic veneer crowns done with optiview software and readings were recorded in Commission Internationale de I’ Eclairge {CIELAB} system and dE value was calculated. Statistical Analysis Statistical analysis was done by using Paired t-test. Results Spectrophotometric analysis of all the veneers cemented with opaque luting agent were lighter in shade due to significant change in dL value. Veneers cemented with transparent luting agent were darker in shade due to significant change in the dL value. Conclusion Opaque luting agent gives lighter shade and transparent luting agent gives darker shade to ceramic veneers fabricated with 2L1.5 and B2 shades. PMID:26501014

  13. Fracture resistance and failure mode of posterior fixed dental prostheses fabricated with two zirconia CAD/CAM systems

    PubMed Central

    López-Suárez, Carlos; Gonzalo, Esther; Peláez, Jesús; Rodríguez, Verónica

    2015-01-01

    Background In recent years there has been an improvement of zirconia ceramic materials to replace posterior missing teeth. To date little in vitro studies has been carried out on the fracture resistance of zirconia veneered posterior fixed dental prostheses. This study investigated the fracture resistance and the failure mode of 3-unit zirconia-based posterior fixed dental prostheses fabricated with two CAD/CAM systems. Material and Methods Twenty posterior fixed dental prostheses were studied. Samples were randomly divided into two groups (n=10 each) according to the zirconia ceramic analyzed: Lava and Procera. Specimens were loaded until fracture under static load. Data were analyzed using Wilcoxon´s rank sum test and Wilcoxon´s signed-rank test (P<0.05). Results Partial fracture of the veneering porcelain occurred in 100% of the samples. Within each group, significant differences were shown between the veneering and the framework fracture resistance (P=0.002). The failure occurred in the connector cervical area in 80% of the cases. Conclusions All fracture load values of the zirconia frameworks could be considered clinically acceptable. The connector area is the weak point of the restorations. Key words:Fixed dental prostheses, zirconium-dioxide, zirconia, fracture resistance, failure mode. PMID:26155341

  14. 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.

  15. The Effect of Veneer Layers on the Bending Shear Strength and Delamination of Laminated Veneer Lumber (LVL) from Oil Palm Trunk (OPT)

    NASA Astrophysics Data System (ADS)

    Jamaludin, M. A.; Nordin, K.; Bahari, S. A.; Ahmad, M.

    2010-03-01

    The aim of this study was to evaluate the effects of the number of veneer layers on the bending shear strength and delamination of Laminated Veneer Lumber (LVL) from oil palm trunk (OPT). Five (5), Six (6) and Seven (7) veneer layers of OPT LVL were manufactured. The dimension of the boards was 45 cm by 45 cm by 1.9 cm. The boards were hot pressed for 13 minutes at a pressure of 31 kgf per m2. Urea formaldehyde (UF) supplied by a local adhesive manufacturer was used as the binder for the boards. The bending shear tests consisted of the edgewise and flatwise tests, whereas the delamination test consisted of the cold and hot water boil tests. The preparation of the test specimens and tests set-up was in accordance to the Japanese Standards, JAS-1991 [1]. Six replications were used for each test. The results were analyzed by Analysis of Variance (ANOVA) using the Duncan's Multiple Range Test to test for significant differences. The results indicated that as the number of layers increased the strength also increased. All the boards passed the standard. The difference in strength between the different types of samples was significant at 95 percent confidence level. Bending shear failures were primarily in the veneers. It is possible to use the boards as light weight interior building and furniture components. Over the years, the supply of quality timber resources from the natural forest has decrease as the wood-based industry experienced rapid growth. The supply of rubberwood for the furniture industry is also decreasing as a result of increase latex price. Accordingly, OPT LVL can be an alternative or supplementary raw material for the wood-based industry.

  16. Enamel microabrasion for aesthetic management of dental fluorosis

    PubMed Central

    Pandey, Pallavi; Ansari, Afroz Alam; Moda, Preeti; Yadav, Madhulika

    2013-01-01

    Fluorosis has increased in recent times due to fluoridation of drinking water and addition of fluoride to various edible items, which leads to unaesthetic appearance of teeth visible at close quarters. The enamel microabrasion technique is a conservative method that improves the appearance of the teeth by restoring bright and superficial smoothness, without causing significant structural loss. The aim of this article is to describe an easy technique for managing mild to moderate dental fluorosis using Opalustre (Ultradent Products) microabrasion slurry. This conservative approach may be considered an interesting alternative to more invasive prosthetic techniques like composite resin restorations, ceramic veneers or crown fabrications. PMID:24121810

  17. Enamel microabrasion for aesthetic management of dental fluorosis.

    PubMed

    Pandey, Pallavi; Ansari, Afroz Alam; Moda, Preeti; Yadav, Madhulika

    2013-01-01

    Fluorosis has increased in recent times due to fluoridation of drinking water and addition of fluoride to various edible items, which leads to unaesthetic appearance of teeth visible at close quarters. The enamel microabrasion technique is a conservative method that improves the appearance of the teeth by restoring bright and superficial smoothness, without causing significant structural loss. The aim of this article is to describe an easy technique for managing mild to moderate dental fluorosis using Opalustre (Ultradent Products) microabrasion slurry. This conservative approach may be considered an interesting alternative to more invasive prosthetic techniques like composite resin restorations, ceramic veneers or crown fabrications. PMID:24121810

  18. Complete mouth reconstruction with implant-supported fixed partial dental prostheses fabricated with zirconia frameworks: a 4-year clinical follow-up.

    PubMed

    Puri, Shweta; Parciak, Ewa C; Kattadiyil, Mathew T

    2014-09-01

    Few scientific reports regarding the success of complete mouth partial fixed dental prostheses frameworks fabricated with zirconia are available, especially when dental implants serve as the abutments. A complete mouth reconstruction with zirconia frameworks veneered with feldspathic porcelain is reported involving a 65-year-old white woman who presented with partial edentulism and an unrestorable remaining dentition. After examination, 14 implants were planned (8 in the maxillary arch and 6 in the mandibular arch), and implant-supported zirconia framework screw-retained partial fixed dental prostheses (ISZPFDPs) were fabricated and made in sections for easier retrievability and management. No major complications were encountered during follow-up appointments at 6-month intervals for 4 years. However, minor fractures of the veneering ceramic were noted 4 years after placement. The ISZPFDPs were well accepted by the patient and had a favorable outcome in terms of patient acceptability and success, despite some complications. PMID:24674806

  19. 46 CFR 32.56-50 - Combustible veneers-T/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... REQUIREMENTS Structural Fire Protection for Tank Ships With a Keel Laying Date On or After January 1, 1975 § 32... veneers on bulkheads, linings, and ceilings within accommodation, service, or control spaces must be 2... spaces, corridors, stairway enclosures, or control spaces must be an approved interior finish material...

  20. Role of core support material in veneer failure of brittle layer structures.

    PubMed

    Hermann, Ilja; Bhowmick, Sanjit; Lawn, Brian R

    2007-07-01

    A study is made of veneer failure by cracking in all-ceramic crown-like layer structures. Model trilayers consisting of a 1 mm thick external glass layer (veneer) joined to a 0.5 mm thick inner stiff and hard ceramic support layer (core) by epoxy bonding or by fusion are fabricated for testing. The resulting bilayers are then glued to a thick compliant polycarbonate slab to simulate a dentin base. The specimens are subjected to cyclic contact (occlusal) loading with spherical indenters in an aqueous environment. Video cameras are used to record the fracture evolution in the transparent glass layer in situ during testing. The dominant failure mode is cone cracking in the glass veneer by traditional outer (Hertzian) cone cracks at higher contact loads and by inner (hydraulically pumped) cone cracks at lower loads. Failure is deemed to occur when one of these cracks reaches the veneer/core interface. The advantages and disadvantages of the alumina and zirconia core materials are discussed in terms of mechanical properties-strength and toughness, as well as stiffness. Consideration is also given to the roles of interface strength and residual thermal expansion mismatch stresses in relation to the different joining methods. PMID:17078086

  1. ESTIMATING THE SIZE OF LATE VENEER IMPACTORS FROM IMPACT-INDUCED MIXING ON MERCURY

    SciTech Connect

    Rivera-Valentin, E. G.; Barr, A. C.

    2014-02-10

    Late accretion of a ''veneer'' of compositionally diverse planetesimals may introduce chemical heterogeneity in the mantles of the terrestrial planets. The size of the late veneer objects is an important control on the angular momenta, eccentricities, and inclinations of the terrestrial planets, but current estimates range from meter-scale bodies to objects with diameters of thousands of kilometers. We use a three-dimensional global Monte Carlo model of impact cratering, excavation, and ejecta blanket formation to show that evidence of mantle heterogeneity can be preserved within ejecta blankets of mantle-exhuming impacts on terrestrial planets. Compositionally distinct provinces implanted at the time of the late veneer are most likely to be preserved in bodies whose subsequent geodynamical evolution is limited. Mercury may have avoided intensive mixing by solid-state convection during much of its history. Its subsequent bombardment may have then excavated evidence of primordial mantle heterogeneity introduced by the late veneer. Simple geometric arguments can predict the amount of mantle material in the ejecta blanket of mantle-exhuming impacts, and deviations in composition relative to geometric predictions can constrain the length-scale of chemical heterogeneities in the subsurface. A marked change in the relationship between mantle and ejecta composition occurs when chemically distinct provinces are ∼250 km in diameter; thus, evidence of bombardment by thousand-kilometer-sized objects should be readily apparent from the variation in compositions of ejecta blankets in Mercury's ancient cratered terrains.

  2. Effect of Er:YAG laser on debonding strength of laminate veneers

    PubMed Central

    Iseri, Ufuk; Oztoprak, Mehmet Oguz; Ozkurt, Zeynep; Kazazoglu, Ender; Arun, Tulin

    2014-01-01

    Objective: The purpose of this study was to evaluate the debonding strength of laminate veneers after using erbium-doped: yttrium aluminium garnet (Er:YAG) laser. Materials and Methods: A total of 60 bovine mandibular incisor teeth were divided into two groups (n = 30). Cylindrical specimens (0.7 mm × 5 mm) were fabricated from Empress II ceramic. Then, they were cemented to incisors using dual-cured resin cement (Variolink II). In the first group, no laser application was performed. The Er:YAG laser was applied on each laminate veneer at the test group for 9 s by using the scanning method. Shear force to remove the laminate veneers were applied with universal testing machine at a crosshead speed of 1 mm/min. Results: Results of this study exhibited significant differences between the control (27.28 ± 2.24 MPa) and test group (3.44 ± 0.69 MPa) (P < 0.05). Conclusion: This study shows that application of Er:YAG laser decreased the bond strength of laminate veneers. PMID:24966747

  3. Veneers, rinds, and fracture fills: Relatively late alteration of sedimentary rocks at Meridiani Planum, Mars

    USGS Publications Warehouse

    Knoll, A.H.; Jolliff, B.L.; Farrand, W. H.; Bell, J.F., III; Clark, B. C.; Gellert, Ralf; Golombek, M.P.; Grotzinger, J.P.; Herkenhoff, K. E.; Johson, J.R.; McLennam, S.M.; Morris, R.; Squyres, S. W.; Sullivan, R.; Tosca, N.J.; Yen, A.; Learner, Z.

    2008-01-01

    Veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at Meridiani Planum, Mars. The chemistry of submillimeter thick, buff-colored veneers reflects multiple processes at work since the establishment of the current plains surface. Veneer composition is dominated by the mixing of silicate-rich dust and sulfate-rich outcrop surface, but it has also been influenced by mineral precipitation, including NaCl, and possibly by limited physical or chemical weathering of sulfate minerals. Competing processes of chemical alteration (perhaps mediated by thin films of water or water vapor beneath blanketing soils) and sandblasting of exposed outcrop surfaces determine the current distribution of veneers. Dark-toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture, halite precipitation, and possible minor sulfate removal. Cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact. These appear to reflect limited groundwater activity along the margins of fractures, cementing mechanically introduced fill derived principally from outcrop rocks. The limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping Meridiani strata were exposed on the plains surface. Copyright 2008 by the American Geophysical Union.

  4. Fracture resistance of porcelain veneered zirconia crowns with exposed lingual zirconia for anterior teeth after thermal cycling: An in vitro study

    PubMed Central

    Amir Rad, Fatemeh A.; Succaria, Faysal G.; Morgano, Steven M.

    2015-01-01

    Statement of problem In some clinical conditions minimally invasive complete crown tooth preparations are indicated. This is especially true when gross removal of tooth structure would weaken the remaining tooth or violate the vitality of the dental pulp. Objective The purpose of this study was to investigate the influence of (1) exposed lingual zirconia with veneered zirconia crowns, and (2) reduced lingual thickness of monolithic lithium disilicate crowns on the fracture resistance of the crowns after cyclic loading. Metal-ceramic crowns with exposed lingual metal served as controls. Materials and methods Twenty-four maxillary central incisor crowns were fabricated in identical shape on metal testing dies in 3 groups: metal-ceramic crowns (MC, n = 8), veneered zirconia crowns (VZ, n = 8), and monolithic lithium disilicate crowns (MO, n = 8). A conservative preparation design with 0.75 mm lingual clearance was used for each crown system. All crowns were cemented to their corresponding crown preparations with self-adhesive resin cement (Multilink Automix). The crowns were subjected to 1000 cycles of thermal cycling, then cyclic loading of 111 N by means of a stainless steel ball, and 50,000 cycles of loading were applied for the fatigue test. Fatigue loading was followed by a continuously increasing compressive load, at a crosshead speed of 1 mm/min until failure. The compressive load (N) required to cause failure was recorded. Means were calculated and analyzed with one-way ANOVA and the Tukey HSD test (α = .05). Results There was a significant difference between MO vs. MC (P = .0001), MO vs. VZ (P = .0001), and VZ vs. MC (P = .012). Conclusions There was a significant difference in the mean fracture resistance of MC, VZ, and MO crowns in this in vitro study. The MC group recorded the highest mean fracture strength. PMID:26082571

  5. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients

    PubMed Central

    Aktas, Guliz; Sahin, Erdal; Vallittu, Pekka; Özcan, Mutlu; Lassila, Lippo

    2013-01-01

    This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core–veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min−1). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)−(39.7±4.7) and (27.4±5.6)−(35.9±4.7) MPa with and without colouring, respectively) (P<0.001). While in zirconia–veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering <1/3 of the substrate surface, in the metal–ceramic group, veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core–veneer adhesion. Metal–ceramic adhesion was more reliable than all zirconia–veneer ceramics tested. PMID:24158142

  6. Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients.

    PubMed

    Aktas, Guliz; Sahin, Erdal; Vallittu, Pekka; Ozcan, Mutlu; Lassila, Lippo

    2013-12-01

    This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min(-1)). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)-(39.7±4.7) and (27.4±5.6)-(35.9±4.7) MPa with and without colouring, respectively) (P<0.001). While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering <1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested. PMID:24158142

  7. Zirconia-based dental crown to support a removable partial denture: a three-dimensional finite element analysis using contact elements and micro-CT data.

    PubMed

    Rocha, Eduardo Passos; Anchieta, Rodolfo Bruniera; de Almeida, Erika Oliveira; Freitas, Amilcar Chagas; Martini, Ana Paula; Sotto-Maior, Bruno Sales; Luersen, Marco Antonio; Ko, Ching Chang

    2015-01-01

    Veneer fracture is the most common complication in zirconia-based restorations. The aim of this study was to evaluate the mechanical behavior of a zirconia-based crown in a lower canine tooth supporting removable partial denture (RPD) prosthesis, varying the bond quality of the veneer/coping interface. Microtomography (μCT) data of an extracted left lower canine were used to build the finite element model (M) varying the core material (gold core - MAu; zirconia core - MZi) and the quality of the veneer/core interface (complete bonded - MZi; incomplete bonded - MZi-NL). The incomplete bonding condition was only applied for zirconia coping by using contact elements (Target/Contact) with 0.3 frictional coefficients. Stress fields were obtained using Ansys Workbench 10.0. The loading condition (L = 1 N) was vertically applied at the base of the RPD prosthesis metallic support towards the dental apex. Maximum principal (σmax) and von Mises equivalent (σvM) stresses were obtained. The σmax (MPa) for the bonded condition was similar between gold and zirconia cores (MAu, 0.42; MZi, 0.40). The incomplete bonded condition (MZi-NL) raised σmax in the veneer up to 800% (3.23 MPa) in contrast to the bonded condition. The peak of σvM increased up to 270% in the MZi-NL. The incomplete bond condition increasing the stress in the veneer/zirconia interface. PMID:25331825

  8. Comminution process to produce engineered wood particles of uniform size and shape with disrupted grain structure from veneer

    DOEpatents

    Dooley, James H; Lanning, David N

    2013-07-30

    Comminution process of wood veneer to produce wood particles, by feeding wood veneer in a direction of travel substantially normal to grain through a counter rotating pair of intermeshing arrays of cutting discs arrayed axially perpendicular to the direction of veneer travel, wherein the cutting discs have a uniform thickness (Td), to produce wood particles characterized by a length dimension (L) substantially equal to the Td and aligned substantially parallel to grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) substantially equal to the veneer thickness (Tv) and aligned normal to W and L, wherein the W.times.H dimensions define a pair of substantially parallel end surfaces with end checking between crosscut fibers.

  9. Dental Hygienist.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of dental hygienist, lists technical competencies and competency builders for 13 units pertinent to the health technologies cluster in general and 9 units specific to the occupation of dental hygienist. The following skill areas are covered in…

  10. Dental radiology.

    PubMed

    Woodward, Tony M

    2009-02-01

    Dental radiology is the core diagnostic modality of veterinary dentistry. Dental radiographs assist in detecting hidden painful pathology, estimating the severity of dental conditions, assessing treatment options, providing intraoperative guidance, and also serve to monitor success of prior treatments. Unfortunately, most professional veterinary training programs provide little or no training in veterinary dentistry in general or dental radiology in particular. Although a technical learning curve does exist, the techniques required for producing diagnostic films are not difficult to master. Regular use of dental x-rays will increase the amount of pathology detected, leading to healthier patients and happier clients who notice a difference in how their pet feels. This article covers equipment and materials needed to produce diagnostic intraoral dental films. A simplified guide for positioning will be presented, including a positioning "cheat sheet" to be placed next to the dental x-ray machine in the operatory. Additionally, digital dental radiograph systems will be described and trends for their future discussed. PMID:19410234

  11. Fractographic Analysis of a Dental Zirconia Framework: a Case Study on Design Issues

    PubMed Central

    Lohbauer, Ulrich; Amberger, Gudrun; Quinn, George D.; Scherrer, Susanne S.

    2011-01-01

    Fractographic analysis of clinically failed dental ceramics can provide insights as to the failure origin and related mechanisms. One anterior 6-unit all-ceramic zirconia fixed partial denture (FPD) (Cercon®) has been clinically recovered and examined using qualitative fractography. The purpose was to identify the fracture origin and to state the reasons for failure. The recovered parts of the zirconia FPD were microscopically examined to identify classic fractographic patterns such as arrest lines, hackle, twist hackle and wake hackle. The direction of crack propagation was mapped and interpreted back to the origin of failure at the interface of the occlusalpalatal tip of the core and the veneering ceramic. An inappropriate core drop design favoring localized stress concentration combined with a pore cluster in the veneering ceramic at the core tip interface were the reasons for this premature through-the-core thickness failure. PMID:20826369

  12. Composite laminate veneers with a continuous inorganic phase comprising microporous sintered glass fiber networks.

    PubMed

    Ehrnford, L

    1983-10-01

    Veneers were made from sheets consisting of a three-dimensional network of sintered ultrafine glass fibers. The sheets were molded by a vacuum-pressure technique and then impregnated with a liquid resin. Impregnation was performed with a method that enabled the depth of penetration to be monitored. The resin was cured with UV radiation under N2 protection. By the use of TiO2-containing resins the veneer achieved an enamel-like appearance. An in vitro toothbrush dentifrice abrasion test showed a high wear resistance and persisting surface luster. Scanning electron and light microscopy showed fairly smooth and flat light-reflecting glass structures in the surface. PMID:6362318

  13. Indirect porcelain veneers in periodontally compromised teeth. The hybrid technique: a case report.

    PubMed

    Garcia-Baeza, David; Saavedra, Carlos; Garcia-Adámez, Ramón

    2015-01-01

    The loss of periodontal structure causes an esthetic problem for many patients, especially when the esthetic zone is compromised. Among the various types of solutions is the use of composite resins. While this procedure is not aggressive towards tooth structure, it does require the clinician to have a precise technique, and demands strict longterm maintenance. 1 Another way of treating the compromised teeth is with porcelain veneers. This procedure is especially difficult, however, if carried out on periodontal teeth, as it requires preparation along the roots. 2 The intention of the hybrid technique described in this article is to combine both of these procedures in order to obtain a less aggressive treatment with precise management of the soft tissue and an adequate esthetic outcome. The hybrid technique consists of enlarging the root portion of the teeth with composite resin to obtain a less aggressive tooth preparation, and thereafter placing porcelain veneers. PMID:26171444

  14. Furnace veneering systems of special design help achieve energy reduction goals at Armco

    SciTech Connect

    Caspersen, L.J.

    1982-12-01

    A steel company conserves energy by veneering reheat furnaces with a ceramic fiber modular system. The furnace lining system incorporates several grades of veneering materials (modules, cements, coatings) whose application is matched to the exact conditions in the furnace. Zoned linings utilize a combination of grades of alumina-silica modules to achieve thermally efficient yet durable performance. High temperature cements exhibit good tackiness, easy module penetration and high strength retention after firing. A protective coating is sprayed in a thin layer over the modules and can be easily reapplied at a later date should it be necessary. Benefits include greater thermal control (temperature responsiveness and heating uniformity), less over-firing, less fuel use, and less heat loss. Fuel efficiency is increased by 20 to 50%.

  15. Comparison of shear bond strength of two veneering ceramics to zirconia

    PubMed Central

    Rismanchian, Mansour; Shafiei, Soufia; Askari, Navid; Khodaeian, Niloufar

    2012-01-01

    Background: Chip-off fracture of veneering porcelain has been described as the most frequent reason for the failure of zirconia-based fixed partial dentures. The purpose of this study was to evaluate the shear bond strength (SBS) of two commercial zirconia core ceramics to their corresponding veneering ceramics. Materials and Methods: Zirconia disks with 7-mm diameter and 3-mm height were prepared (Cercon and Biodenta systems) and veneered with recommended layering ceramics (Cercon ceram and 2 in 1 ceramic, respectively) (n = 10). The disks were polished with diamond paste and airborne-particle abraded before layering. The specimens were mounted in a T-shaped metal holder using autopolymerized acrylic resin and stored in 37°C distilled water for one week, after which they were subjected to thermal cycling. SBS of zirconia core to veneering ceramic was measured using a universal testing machine and failure modes were determined microscopically. Data were analyzed using t test (α < 0.05). Results: Mean (±SD) SBS values were 27.19(±3.43) and 28.22(±4.08) MPa for Cercon and Biodenta systems, respectively, with no significant difference. Biodenta system showed more adhesive failure compared to more combined (adhesive and cohesive) failures in Cercon system. Conclusion: Within the limitations of this study it can be concluded that SBS of Biodenta and Cercon specimens were nearly the same, but the fracture mode of these two systems were different. Since Biodenta fracture pattern was predominantly adhesive, it seems that maybe Biodenta porcelain was stronger than Cercon porcelain where as its adhesive bond was weaker. PMID:23559931

  16. Influence of surface modification techniques on shear bond strength between different zirconia cores and veneering ceramics

    PubMed Central

    Rismanchian, Mansour; Savabi, Omid; Ashtiani, Alireza Hashemi

    2011-01-01

    PURPOSE Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain. MATERIALS AND METHODS Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with 110 µm Al2O3 particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey's HSD Past hoc, and T-test were selected to analyzed the data (α=0.05). RESULTS In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups. CONCLUSION Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia-porcelain. PMID:22259706

  17. 46 CFR 32.56-50 - Combustible veneers-T/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Combustible veneers-T/ALL. 32.56-50 Section 32.56-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Structural Fire Protection for Tank Ships With a Keel Laying Date On or After January 1, 1975 § 32.56-50 Combustible veneers—T/ALL....

  18. 46 CFR 32.56-50 - Combustible veneers-T/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Combustible veneers-T/ALL. 32.56-50 Section 32.56-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Structural Fire Protection for Tank Ships With a Keel Laying Date On or After January 1, 1975 § 32.56-50 Combustible veneers—T/ALL....

  19. 46 CFR 32.56-50 - Combustible veneers-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Combustible veneers-T/ALL. 32.56-50 Section 32.56-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Structural Fire Protection for Tank Ships With a Keel Laying Date On or After January 1, 1975 § 32.56-50 Combustible veneers—T/ALL....

  20. 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.

  1. Veneering technique for a Ti-6Al-7Nb framework used in a resin-bonded fixed partial denture with a highly filled indirect composite.

    PubMed

    Matsumura, Hideo; Yoneyama, Takayuki; Shimoe, Saiji

    2002-12-01

    This article presents a veneering technique for fixed partial denture frameworks made from a Ti-6Al-7Nb alloy. The fixed partial denture framework was prepared with a magnesia-based mold material and a centrifugal casting machine. An esthetic veneer was fabricated with a highly filled dual-polymerized composite material and a metal-conditioning agent. This technique can be applied as a standardized veneering procedure for the titanium alloy, for which porcelain fusing is currently difficult. PMID:12488858

  2. Effects of coloring procedures on zirconia/veneer ceramics bond strength

    PubMed Central

    Özat, Pelin; Eroğlu, Erdal

    2014-01-01

    PURPOSE The most common failure seen in restorations with a zirconia core is total or layered delamination of the ceramic veneer. In the present study, the shear bond strengths between veneering ceramics and colored zirconia oxide core materials were evaluated. MATERIALS AND METHODS Zirconia discs (15 × 12 × 1.6 mm) were divided into 11 groups of 12 discs each. Groups were colored according to the Vita Classic scale: A3, B1, C4, D2, and D4. Each group was treated with the recommended shading time for 3 s, or with prolonged shading for 60 s, except for the control group. Samples were veneered with 3 mm thick and 3.5 mm in diameter translucent ceramic and subjected to shear test in a universal testing machine with a crosshead speed of 1 mm/min. One-way analysis of variance (ANOVA) and Tukey's HSD tests were used for comparisons of the groups having the same shading times. A paired t-test was used for groups of the same color (3 s/60 s). RESULTS Among the 11 groups investigated C4 (3 s) had the highest bond strength with a value of 36.40 MPa, while A3 (3 s) showed the lowest bond strength with a value of 29.47 MPa. CONCLUSION Coloring procedures can affect zirconia/ceramic bond strength. However, the results also showed that bond strengths of all the investigated groups were clinically acceptable. PMID:25551004

  3. Development of partial rock veneers by root throw in a subalpine setting

    USGS Publications Warehouse

    Osterkamp, W.R.; Toy, T.J.; Lenart, M.T.

    2006-01-01

    Rock veneers stabilize hillslope surfaces, occur especially in areas of immature soil, and form through a variety of process sets that includes root throw. Near Westcliffe, Colorado, USA, data were collected from a 20 ?? 500 m transect on the east slope of the Sangre de Cristo Mountains. Ages of pit/mound complexes with rock fragments exposed at the surface by root throw ranged from recent (freshly toppled tree) to unknown (complete tree decay). Calculations based on dimensions of the pit/mound complexes, estimated time of free topppling, sizes of exposed rock fragments, and percentage rock covers at pit/mound complexes, as well as within the transect area, indicate that recent rates of root throw have resulted in only partial rock veneering since late Pleistocene deglaciation. Weathering of rock fragments prevent development of an extensive rock veneer and causes a balance, achieved within an estimated 700 years, between the rates of rock-fragment exposure by root throw and clast disintegration by chemical reduction. The estimated rate of rock-fragment reduction accounts for part of the fluvial sediment yields observed for forested subalpine areas of western North America. Copyright ?? 2005 John Wiley & Sons, Ltd.

  4. Microspectral analysis with laser in microleakage evaluation between infrastructure and veneer materials in fixed partial dentures

    NASA Astrophysics Data System (ADS)

    Negrutiu, Meda L.; Sinescu, Cosmin; Draganescu, Gheorghe; Todea, Carmen; Dodenciu, Dorin; Rominu, Roxana

    2008-02-01

    The microleakage at the interface between the metal infrastructure and the veneering part of the fixed partial dentures are a common problem of aesthetic dentistry. It is possible to use the method of laser microspectral analysis for investigations of microleakage at the metal-veneering material interfaces in fixed partial prostheses. The laser microspectral analysis device LMA-10 (Carl Zeiss, Jena) was used equipped with a diffraction spectrometer PGS-2 (Carl Zeiss, Jena). Different fixed partial dentures were used to determine the microleakage between the metal infrastructure and the veneering material. The distribution of chemical elements at interface infiltration was investigated, making a series of craters and establishing the spectra of the vapours emitted from the craters. Data was gathered in various tables of chemical elements showing the quality and the quantity of microleakage. The laser microspectral analysis is a punctual method of analysis, which allows to investigate small quantities of materials of around 0.1 μg. This method allows to establish the content of atoms and molecules and to perform semi-quantitative and quantitative analysis. By this method it is possible to establish trace elements, i. e. with concentration of ppm (parts per million).

  5. Effect of surface treatment and liner material on the adhesion between veneering ceramic and zirconia.

    PubMed

    Yoon, Hyung-in; Yeo, In-sung; Yi, Yang-jin; Kim, Sung-hun; Lee, Jai-bong; Han, Jung-suk

    2014-12-01

    Fully sintered zirconia blocks, each with one polished surface, were treated with one of the followings: 1) no treatment, 2) airborne-particle abrasion with 50μm alumina, and 3) airborne-particle abrasion with 125μm alumina. Before veneering with glass ceramic, either liner Α or liner B were applied on the treated surfaces. All veneered blocks were subjected to shear force in a universal testing machine. For the groups with liner A, irrespective of the particle size, air abrasion on Y-TZP surfaces provided greater bond strength than polishing. Application of liner B on an abraded zirconia surface yielded no significant influence on the adhesion. In addition, specimens with liner A showed higher bond strength than those with liner B, if applied on roughened surfaces. Fractured surfaces were observed as mixed patterns in all groups. For the liner A, surface treatment was helpful in bonding with veneering ceramic, while it was ineffective for the liner B. PMID:25282467

  6. Activation of wood surfaces for glue bonds by mechanical pre-treatment and its effects on some properties of veneer surfaces and plywood panels

    NASA Astrophysics Data System (ADS)

    Aydin, İsmail

    2004-06-01

    Some chemical pre-treatments with chemical reagents are widely applied to wood surfaces in order to improve bonding ability, wettability and reactivate wood surfaces for glue-wood bonds. Besides these chemical treatments, some mechanical pre-treatments such as sanding and planing can be applied to get a fresh surface which eliminates bonding problems and improves glue bonding of wood. In this study, 2 mm thick rotary cut veneers obtained from steamed beech ( Fagus orientalis) logs were used as material. Both air-drying and oven-drying methods were used for drying veneer. After drying, the surfaces of some veneers were sanded with 100 and 180 grit sandpapers. Three-layer-plywood panels were produced from sanded and non-sanded veneers by using urea formaldehyde and phenol formaldehyde glue resins to evaluate the effects of sanding some mechanical properties of plywood. Changes in pH, surface roughness and adhesive wettability of veneers were evaluated. Wettability of veneers was assessed with contact angle measurements according to the sessile drop method. Both veneer and plywood properties investigated in this study improved clearly after the sanding process. Shear and bending strength values of plywood panels manufactured from sanded and non-sanded veneers were vary depending on glue types and veneer drying methods.

  7. Dental Implants

    MedlinePlus Videos and Cool Tools

    ... facts so you can make an informed decision as to whether dental implants are right for your ... the jaw bone. It’s obviously not the same as the original connection , but functions just the same. ...

  8. Dental Fluorosis

    MedlinePlus

    ... when children regularly consume fluoride during the teeth-forming years, age 8 and younger. Most dental fluorosis ... over a long period when the teeth are forming under the gums. Only children aged 8 years ...

  9. Dental Caries (Tooth Decay)

    MedlinePlus

    ... Find Data by Topic > Dental Caries (Tooth Decay) Dental Caries (Tooth Decay) Main Content Dental caries (tooth decay) remains the most prevalent chronic ... important source of information on oral health and dental care in the United States since the early ...

  10. Post-fatigue fracture resistance of metal core crowns: press-on metal ceramic versus a conventional veneering system

    PubMed Central

    Agustín-Panadero, Rubén; Campos-Estellés, Carlos; Labaig-Rueda, Carlos

    2015-01-01

    Background The aim of this in vitro study was to compare the mechanical failure behavior and to analyze fracture characteristics of metal ceramic crowns with two veneering systems – press-on metal (PoM) ceramic versus a conventional veneering system – subjected to static compressive loading. Material and Methods Forty-six crowns were constructed and divided into two groups according to porcelain veneer manufacture. Group A: 23 metal copings with porcelain IPS-InLine veneering (conventional metal ceramic). Group B: 23 metal copings with IPS-InLine PoM veneering porcelain. After 120,000 fatigue cycles, the crowns were axially loaded to the moment of fracture with a universal testing machine. The fractured specimens were examined under optical stereomicroscopy and scanning electron microscope. Results Fracture resistance values showed statistically significant differences (Student’s t-test) regarding the type of ceramic veneering technique (p=0.001): Group A (conventional metal ceramics) obtained a mean fracture resistance of 1933.17 N, and Group B 1325.74N (Press-on metal ceramics). The most common type of fracture was adhesive failure (with metal exposure) (p=0.000). Veneer porcelain fractured on the occlusal surface following a radial pattern. Conclusions Metal ceramic crowns made of IPS InLine or IPS InLine PoM ceramics with different laboratory techniques all achieved above-average values for clinical survival in the oral environment according to ISO 6872. Crowns made with IPS InLine by conventional technique resisted fracture an average of 45% more than IPS InLine PoM fabricated with the press-on technique. Key words:Mechanical failure, conventional feldspathic, pressable ceramic, chewing simulator, thermocycling, compressive testing, fracture types, scanning electron microscope. PMID:26155346

  11. Influence of porcelain veneering on the marginal fit of Digident and Lava CAD/CAM zirconia ceramic crowns

    PubMed Central

    Pak, Hyun-Soon; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun

    2010-01-01

    PURPOSE Marginal fit is a very important factor considering the restoration's long-term success. However, adding porcelain to copings can cause distortion and lead to an inadequate fit which exposes more luting material to the oral environment and causes secondary caries. The purpose of this study was to compare the marginal fit of 2 different all-ceramic crown systems before and after porcelain veneering. This study was also intended to verify the marginal fit of crowns originated from green machining of partially sintered blocks of zirconia (Lava CAD/CAM system) and that of crowns obtained through machining of fully sintered blocks of zirconia (Digident CAD/CAM system). MATERIALS AND METHODS 20 crowns were made per each system and the marginal fit was evaluated through a light microscope with image processing (Accura 2000) at 50 points that were randomly selected. Each crown was measured twice: the first measurement was done after obtaining a 0.5 mm coping and the second measurement was done after porcelain veneering. The means and standard deviations were calculated and statistical inferences among the 2 groups were made using independent t-test and within the same group through paired t-test. RESULTS The means and standard deviations of the marginal fit were 61.52 ± 2.88 µm for the Digident CAD/CAM zirconia ceramic crowns before porcelain veneering and 83.15 ± 3.51 µm after porcelain veneering. Lava CAD/CAM zirconia ceramic crowns showed means and standard deviations of 62.22 ± 1.78 µm before porcelain veneering and 82.03 ± 1.85 µm after porcelain veneering. Both groups showed significant differences when analyzing the marginal gaps before and after porcelain veneering within each group. However, no significant differences were found when comparing the marginal gaps of each group before porcelain veneering and after porcelain veneering as well. CONCLUSION The 2 all-ceramic crown systems showed marginal gaps that were within a reported clinically

  12. Spectrophotometric evaluation of the influence of different backgrounds on the color of glass-infiltrated ceramic veneers.

    PubMed

    Charisis, Dimitrios; Koutayas, Spiridon-Oumvertos; Kamposiora, Photini; Doukoudakis, Asterios

    2006-08-01

    The purpose of this spectrophotometric study was to evaluate the influence of different color backgrounds on Vita In-Ceram (Vident) glass-infiltrated ceramic veneers. A total of 50 color background disks were fabricated from Vitadur Alpha 2M2 (n=30) and 5M1 (n=20) dentin porcelain (Vi-dent). Ceramic veneer disks were fabricated from In-Ceram Spinell (n=20) or In-Ceram Alumina (n=20) glass-infiltrated core veneered using Vitadur Alpha 2M2 dentin porcelain. In addition, 10 ceramic veneer disks were fabricated from feldspathic dentin porcelain Vitadur Alpha 2M2. The ceramic veneer specimens were bonded onto the color background specimens using dual-curing luting composite cement, creating the following groups (each n=10): S2M2 (Spinell/2M2), S5M1 (Spinell/5M1), A2M2 (Alumina/2M2), A5M1 (Alumina/5M1), and control (Vitadur Alpha/2M2). L*a*b* color coordinates were measured five times for each specimen using a Vita Easyshade (Vident) spectrophotometer. Mean color differences (deltaE) between each study group and the control group were: 3.79 for S2M2; 7.24 for S5M1; 5.86 for A2M2, and 7.32 for A5M1. Two-way ANOVA showed statistically significant differences in deltaE between all groups. However, a t test revealed that the statistically significant differences only existed between groups S2M2/S5M1, A2M2/A5M1, and S2M2/A2M2. The results suggest that vacuum infiltration with a translucent glass provides the Spinell and Alumina ceramic veneers with increased semi-translucency, which makes them highly influenced by discolored backgrounds. In-Ceram Spinell glass-infiltrated ceramic veneers could be considered as an alternative to conventional feldspathic veneers for the restoration of nondiscolored teeth. Although Spinell and Alumina ceramic veneers could enhance the final color establishment of discolored teeth, the results would not be clinically acceptable. PMID:19655483

  13. Influence of Different Types of Resin Luting Agents on Color Stability of Ceramic Laminate Veneers Subjected to Accelerated Artificial Aging.

    PubMed

    Silami, Francisca Daniele Jardilino; Tonani, Rafaella; Alandia-Román, Carla Cecilia; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2016-01-01

    The aim of this study was to evaluate the influence of accelerated aging (AAA) on the color stability of resin cements for bonding ceramic laminate veneers of different thicknesses. The occlusal surfaces of 80 healthy human molars were flattened. Ceramic laminate veneers (IPS e-max Ceram) of two thicknesses (0.5 and 1.0 mm) were bonded with three types of luting agents: light-cured, conventional dual and self-adhesive dual cement. Teeth without restorations and cement samples (0.5 mm) were used as control. After initial color evaluations, the samples were subjected to AAA for 580 h. After this, new color readouts were made, and the color stability (ΔE) and luminosity (ΔL) data were analyzed. The greatest color changes (p<0.05) occurred when 0.5 mm veneers were fixed with light-cured cement and the lowest when 1.0 mm veneers were fixed with conventional dual cement. There was no influence of the restoration thickness when the self-adhesive dual cement was used. When veneers were compared with the control groups, it was verified that the cement samples presented the greatest alterations (p<0.05) in comparison with both substrates and restored teeth. Therefore, it was concluded that the thickness of the restoration influences color and luminosity changes for conventional dual and light-cured cements. The changes in self-adhesive cement do not depend on restoration thickness. PMID:27007354

  14. Resin-bonded fixed dental prosthesis with a modified treatment surface in a zirconia framework: a case report.

    PubMed

    Viana, Pedro Couto; Portugal, Jaime; Kovacs, Zsolt; Lopes, Ivo; Correia, André

    2016-01-01

    Although resin-bonded fixed dental prostheses (RBFDPs) were developed almost 40 years ago, their implementation in clinical practice did not achieve success due to biomechanical failures of the restorative materials. Nowadays, the evolution of ceramic materials and bonding procedures has allowed for the revival of the dental prosthesis. Zirconia is the dental ceramic with the highest flexural strength under compression. However, there are still some concerns regarding the bonding strength of zirconia to enamel that require further research. In this article, through the presentation of three clinical cases, the authors show how modifying the surface of zirconia frameworks by applying a feldspathic veneering on the retainer's buccal surface allows for a bonding procedure to dental structures. The goal of this treatment method is to simultaneously improve structural strength, esthetic integration, and bonding optimization to enamel. In a 3-year prospective evaluation, this framework modification shows promising results, with a survival rate of 100% and no biological or mechanical complications. PMID:27433551

  15. Dental Calculus Arrest of Dental Caries

    PubMed Central

    Keyes, Paul H.; Rams, Thomas E.

    2016-01-01

    Background An inverse relationship between dental calculus mineralization and dental caries demineralization on teeth has been noted in some studies. Dental calculus may even form superficial layers over existing dental caries and arrest their progression, but this phenomenon has been only rarely documented and infrequently considered in the field of Cariology. To further assess the occurrence of dental calculus arrest of dental caries, this study evaluated a large number of extracted human teeth for the presence and location of dental caries, dental calculus, and dental plaque biofilms. Materials and methods A total of 1,200 teeth were preserved in 10% buffered formal saline, and viewed while moist by a single experienced examiner using a research stereomicroscope at 15-25× magnification. Representative teeth were sectioned and photographed, and their dental plaque biofilms subjected to gram-stain examination with light microscopy at 100× magnification. Results Dental calculus was observed on 1,140 (95%) of the extracted human teeth, and no dental carious lesions were found underlying dental calculus-covered surfaces on 1,139 of these teeth. However, dental calculus arrest of dental caries was found on one (0.54%) of 187 evaluated teeth that presented with unrestored proximal enamel caries. On the distal surface of a maxillary premolar tooth, dental calculus mineralization filled the outer surface cavitation of an incipient dental caries lesion. The dental calculus-covered carious lesion extended only slightly into enamel, and exhibited a brown pigmentation characteristic of inactive or arrested dental caries. In contrast, the tooth's mesial surface, without a superficial layer of dental calculus, had a large carious lesion going through enamel and deep into dentin. Conclusions These observations further document the potential protective effects of dental calculus mineralization against dental caries.

  16. Dental Caries

    PubMed Central

    Burgess, Ralph C.

    1988-01-01

    Dental caries is one of the most prevalent diseases afflicting mankind. It reached a peak in the 1950s but has been declining drastically in recent years in children and young adults. This article describes the three contributing factors in dental caries: microbial plaque, tooth susceptibility, and diet, and discusses practical preventive measures which help to reduce caries incidence. Some of these, such as vaccines and antimicrobial varnishes, are still in the research stages, while others, such as sucrose substitutes, low-calorie sweeteners, and limitation of frequency of sugar snacks are well established and can be promoted by family physicians. PMID:21253193

  17. Evaluation of the color reproducibility of all-ceramic restorations fabricated by the digital veneering method

    PubMed Central

    Kim, Jae-Hong; Kim, Ki-Baek; Kim, Woong-Chul; Kim, Hae-Young

    2014-01-01

    PURPOSE The objective of this study was to evaluate the clinical acceptability of all-ceramic crowns fabricated by the digital veneering method vis-à-vis the traditional method. MATERIALS AND METHODS Zirconia specimens manufactures by two different manufacturing method, conventional vs digital veneering, with three different thickness (0.3 mm, 0.5 mm, 0.7 mm) were prepared for analysis. Color measurement was performed using a spectrophotometer for the prepared specimens. The differences in shade in relation to the build-up method were calculated by quantifying ΔE* (mean color difference), with the use of color difference equations representing the distance from the measured values L*, a*, and b*, to the three-dimensional space of two colors. Two-way analysis of variance (ANOVA) combined with a Tukey multiple-range test was used to analyze the data (α=0.05). RESULTS In comparing means and standard deviations of L*, a*, and b* color values there was no significant difference by the manufacturing method and zirconia core thickness according to a two-way ANOVA. The color differences between two manufacturing methods were in a clinically acceptable range less than or equal to 3.7 in all the specimens. CONCLUSION Based on the results of this study, a carefully consideration is necessary while selecting upper porcelain materials, even if it is performed on a small scale. However, because the color reproducibility of the digital veneering system was within the clinically acceptable range when comparing with conventional layering system, it was possible to estimate the possibility of successful aesthetic prostheses in the latest technology. PMID:24843390

  18. Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks

    PubMed Central

    Turk, Ayse Gozde; Ulusoy, Mubin; Yuce, Mert

    2015-01-01

    PURPOSE To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled (5-55℃, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks. PMID:26816575

  19. Porcelain laminate veneer conditioning for orthodontic bonding: SEM-EDX analysis.

    PubMed

    Aksakalli, Sertac; Ileri, Zehra; Yavuz, Tevfik; Malkoc, Meral Arslan; Ozturk, Nilgun

    2015-09-01

    The purpose of this in vitro study was to evaluate and compare the effects of different surface treatments and laser irradiation on the bond strength of brackets bonded to porcelain laminate veneer. Porcelain laminate veneer specimens were embedded in the centers of acrylic resin blocks. Thirty-nine teeth were used for shear bond strength testing and the remaining three (one tooth for each group) were used for evaluation of the debonded bracket interface. Specimens were randomly divided into three groups, each containing 13 specimens. The details of the groups are as follows: Group SB, sandblasting with alumina particles (50 μm); Group HFA, 9.6 % hydrofluoric acid etching; Group ER, erbium-doped yttrium-aluminum-garnet (Er: YAG) irradiation (from 1 mm distance, 2 W, 10 Hz for 10 s). After conditioning, the upper central brackets were bonded to the porcelain surfaces. Porcelain laminate veneers were examined under stereomicroscope for adhesive remnant index and surface damage after debonding. The highest shear bond strength values were obtained with Group HFA (10.8 ± 3.8 MPa) and Group ER (9.3 ± 1.5 MPa), whereas Group SB revealed the lowest values. Scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis revealed that the silicon level in the porcelain decreased after debonding in all groups. The sandblasting method did not demonstrate any ideal bond strength values; however, the 9.6 % hydrofluoric acid etching and Er: YAG laser did. There were no significant differences among all groups in terms of laminate surface damages. The Er: YAG laser therefore can be selected for ideal bond strength and minimal damage to porcelain laminates. PMID:25344891

  20. [Effect of erosion on strength of dental infiltrated Al2O3 ceramics].

    PubMed

    Xiong, Fang; Yu, Haiyang A; Liao, Yunmao; Zhu, Zhimin; Zhou, Zhongrong; Zhu, Minhao

    2005-12-01

    The objective of the research is to investigate the elements of routine sandblast technique on the evolution of bending strength of dental infiltrated Al2O3 ceramics and the underlying erosion mechanism. The plane specimens of an infiltrated ceramic were manufactured, polished and then tested under the modified pen-like sandblasting apparatus (90 degrees erosive angle and 10 mm sandblasting distance), with different grit sizes, working pressure and disposing time. Half of samples were selected randomly and sintered subsequently with Vitadur alpha veneering porcelain. Before and after sintering, the three-point-bending strengths was measured, and the surfaces of dental porcelain were observed with SEM and LCSM. The bending strength of ceramics decreased significantly after sandblast as compared with that of empty control group. After the procedure of sintering the veneering porcelain, the descending evolution of bending strength slowed down. Under the present manufacturing conditions, grit size effect is prominent among those correlative elements of sand grit size, working pressure and disposing time. And fatigue cracking characterizes the mechanism of erosion of dental infiltrated Al2O3 ceramics. PMID:16422096

  1. THE LAST STAGES OF TERRESTRIAL PLANET FORMATION: DYNAMICAL FRICTION AND THE LATE VENEER

    SciTech Connect

    Schlichting, Hilke E.; Warren, Paul H.; Yin Qingzhu

    2012-06-10

    The final stage of terrestrial planet formation consists of the clean-up of residual planetesimals after the giant impact phase. Dynamically, a residual planetesimal population is needed to damp the high eccentricities and inclinations of the terrestrial planets to circular and coplanar orbits after the giant impact stage. Geochemically, highly siderophile element (HSE) abundance patterns inferred for the terrestrial planets and the Moon suggest that a total of about 0.01 M{sub Circled-Plus} of chondritic material was delivered as 'late veneer' by planetesimals to the terrestrial planets after the end of giant impacts. Here, we combine these two independent lines of evidence for a leftover population of planetesimals and show that: (1) a residual population of small planetesimals containing 0.01 M{sub Circled-Plus} is able to damp the high eccentricities and inclinations of the terrestrial planets after giant impacts to their observed values. (2) At the same time, this planetesimal population can account for the observed relative amounts of late veneer added to the Earth, Moon, and Mars provided that the majority of the accreted late veneer was delivered by small planetesimals with radii {approx}< 10 m. These small planetesimal sizes are required to ensure efficient damping of the planetesimal's velocity dispersion by mutual collisions, which in turn ensures sufficiently low relative velocities between the terrestrial planets and the planetesimals such that the planets' accretion cross sections are significantly enhanced by gravitational focusing above their geometric values. Specifically, we find that, in the limit that the relative velocity between the terrestrial planets and the planetesimals is significantly less than the terrestrial planets' escape velocities, gravitational focusing yields a mass accretion ratio of Earth/Mars {approx}({rho}{sub Circled-Plus }/{rho}{sub mars})(R{sub Circled-Plus }/R{sub mars}){sup 4} {approx} 17, which agrees well with the mass

  2. Rehabilitation of the dominance of maxillary central incisors with refractory porcelain veneers requiring minimal tooth preparation.

    PubMed

    da Cunha, Leonardo Fernandes; Gonzaga, Carla Castiglia; Saab, Rafaella; Mushashe, Amanda Mahammad; Correr, Gisele Maria

    2015-01-01

    Central dominance is an important element of an esthetic smile. Color, form, and size have been suggested as tools for assessing the dominance of maxillary teeth. A spectrophotometer can be used to determine the value, hue, and chroma. Correct sizing of restorations according to the central incisor dominance principle improves not only esthetics but also aspects of occlusion, such as anterior guidance. Refractory porcelain systems can effectively restore the color, shape, emergence profile, and incisal translucency. This report illustrates the esthetic and occlusal rehabilitation of the dominance of maxillary central incisors using fabricated minimal thickness refractory porcelain veneers. PMID:26345102

  3. Dental crowns

    MedlinePlus

    ... cover a tooth Replace a misshapen tooth or dental implant Correct a misaligned tooth Talk to your dentist ... the tooth pulled and replaced with a tooth implant. Your crown could chip or crack: If you grind your teeth or clench your jaw, you may need to ...

  4. Dental Assistant.

    ERIC Educational Resources Information Center

    Michigan State Univ., East Lansing. Coll. of Agriculture and Natural Resources Education Inst.

    This curriculum guide, developed for use in dental assistant education programs in Michigan, describes a task-based curriculum that can help a teacher to develop a classroom management system where students learn by doing. It is based on task analysis and reflects the skills, knowledge, and attitudes that employers expect entry-level dental…

  5. Dental Training Films.

    ERIC Educational Resources Information Center

    Veterans Administration Medical Center, Washington, DC.

    This dental training films catalog is organized into two sections. Section I is a category listing of the films by number and title, indexed according to generalized headings; categories are as follow: anatomy, articulator systems, complete dentures, dental assisting, dental laboratory technology, dental materials, dental office emergencies,…

  6. What I wish I'd learned at dental school.

    PubMed

    Oliver, G R; Lynch, C D; Chadwick, B L; Santini, A; Wilson, N H F

    2016-08-26

    Background Much concern appears to exist as to the scope and content of contemporary dental school programmes, with the oft-cited criticism being made that dental graduates are 'no longer as good as they used to be'.Aim The aim of this project was to survey the views of dentists - both new graduates and more established practitioners - on aspects of their own dental school training they felt had been deficient as well as commenting on what aspects of dental school education they would like to see improved/enhanced in current times.Methods An invitation to complete an Internet-based questionnaire was emailed to the Fellows and Members of the Faculty of General Dental Practice (UK). Topics in the questionnaire included the respondent's own dental education history, how well they felt their dental school training had covered certain clinical and non-clinical topics; and their opinions on areas they felt should be included in contemporary dental school programmes.Results Six hundred and forty-nine responses were received from 3,348 emailed invitations (response rate = 19.4%). Sixty-one percent (395) of respondents were qualified for 10 years or more. Among clinical skills and techniques, a majority of respondents reported they felt they had not had sufficient teaching/training in dental school in surgical endodontics (76%), conscious sedation (72%), root surface debridement (71%), fixed orthodontic appliances (68%), porcelain veneers (63%), implants (56%) and posterior composites (53%). If designing a new dental school programme, the most common topics respondents would seek to include/increase were business and practice management (21%), communication skills (including patient management and leadership skills) (10%), and increased clinical time and experience (8%).Conclusions The findings of this project are of interest and relevance to those working with student dentists and young dental practitioners. A greater emphasis is needed on the teaching of certain non

  7. Dental education and dental practice.

    PubMed Central

    Moore, J R

    1984-01-01

    This paper relates recent modes of dental practice to changes that the public and government are likely to ask the health care professions to make in the future. As usual they are asking for the best of all worlds. First, that we maintain the clinical model to the highest standards of personal dental care based and tested against the best research at our disposal, whilst we ensure there is no reduction in the high technical standards for which british dentists have a reputation. Second, that the profession is required to consider ways of providing care on the medicosocial model for the whole community at an economic level the country will afford. The broad changes in dental education have been reviewed, from the technical apprenticeship to the establishment of strong university departments in teaching hospitals. The importance of a sound biomedical foundation and of research both to education and the credibility of dental practice as a primary health care profession is stressed if the profession is to retain its position as a sister to medicine and not slide down to that of a technical ancillary. PMID:6374141

  8. Tribocorrosion behavior of veneering biomedical PEEK to Ti6Al4V structures.

    PubMed

    Sampaio, Miguel; Buciumeanu, Mihaela; Henriques, Bruno; Silva, Filipe S; Souza, Júlio C M; Gomes, José R

    2016-02-01

    In dentistry, prosthetic structures must be able to support masticatory loads combined with a high biocompatibility and wear resistance in the presence of a corrosive environment. In order to improve the simultaneous wear and corrosion response of highly biocompatible prosthetic structures, a veneering poly-ether-ether-ketone (PEEK) to Ti6Al4V substrate was assessed by tribocorrosion analyses under conditions mimicking the oral environment. Samples were synthesized by hot pressing the PEEK veneer onto Ti6Al4V cylinders. The tribocorrosion tests on Ti6Al4V or PEEK/Ti6Al4V samples were performed on a reciprocating ball-on-plate tribometer at 30N normal load, 1Hz and stroke length of 3mm. The tests were carried out in artificial saliva at 37°C. Open circuit potential (OCP) was measured before, during and after reciprocating sliding tests. The worn surfaces were characterized by scanning electron microscopy. The results revealed a lower wear rate on PEEK combined with a lower coefficient of friction (COF), when compared to Ti6Al4V. In fact, PEEK protected Ti6Al4V substrate against the corrosive environment and wear avoiding the release of metallic ions to the surrounding environment. PMID:26454136

  9. Electroless nickel plating on APTHS modified wood veneer for EMI shielding

    NASA Astrophysics Data System (ADS)

    Liu, Haibing; Li, Jian; Wang, Lijuan

    2010-12-01

    A new activation process was developed for electroless plating to prepare wood-based EMI shielding material. Pd(II) was adsorbed on a wood surface modified with γ-aminopropyltrihydroxysilane (APTHS) formed by the hydrolysis of γ-aminopropyltriethoxysilane (APTES). After reduction of Pd(II), electroless plating was successfully initiated and an Ni-P coating was deposited on the wood veneer. The activation process and resulting coating were characterized by XPS, SEM-EDS and XRD. The metal deposition, surface resistivity and electromagnetic shielding effectiveness were measured. XPS analysis proved that Pd(II) was bonded to the amino group of APTHS and was reduced to Pd(0). The Ni-P coating was uniform, compact and continuous, and consisted of 3.39 wt.% phosphorus and 96.61 wt.% nickel. XRD analysis indicated that the coating was crystalline, which is thought to be related to the low phosphorus content. The plated birch veneers exhibited electromagnetic shielding effectiveness greater than 60 dB in the frequency range 10 MHz-1.5 GHz.

  10. Compatibility of Ce-TZP/Al2O3 nanocomposite frameworks and veneering porcelains.

    PubMed

    Terui, Yuichi; Sato, Kotaro; Goto, Daisuke; Hotta, Yasuhiro; Tamaki, Yukimichi; Miyazaki, Takashi

    2013-01-01

    The aim of this study was to examine the compatibility of Ce-TZP/Al2O3 nanocomposite (CTA) frameworks and veneering porcelains using the Schwickerath crack initiation test and clarify the effects on debonding/crack initiation strength (DIS) of both surface pretreatment (include heat treatment) of the frameworks, type of veneering porcelain varying the coefficient of thermal expansion (CTE), and surface roughness of the frameworks. The surfaces of Ce-TZP/Al2O3 plates were mechanically treated and followed by post-heat treatment. The liner and body porcelains were built up and fired according to the manufacturer's instructions. Surface analyses of the fractured plates showed compatibility with liner porcelains. Since no statistically difference in the DIS was found amongst the different surface treatments, post-heat treatments don't be mandatory. Whereas, since differences in DIS were found when different porcelains with different CTE were used, we concluded the matching of CTE of the porcelain with that of Ce-TZP/Al2O3 was important for successful all-ceramic restorations using Ce-TZP/Al2O3 frameworks. PMID:24088843

  11. Reliability of reduced-thickness and thinly veneered lithium disilicate crowns.

    PubMed

    Silva, N R F A; Bonfante, E A; Martins, L M; Valverde, G B; Thompson, V P; Ferencz, J L; Coelho, P G

    2012-03-01

    The present investigation hypothesized that the reliability of reduced-thickness monolithic lithium disilicate crowns is high relative to that of veneered zirconia (Y-TZP) and comparable with that of metal ceramic (MCR) systems. CAD/CAM first mandibular molar full-crown preparations were produced with uniform thicknesses of either 1.0-mm or 2.0-mm occlusal and axial reduction, then replicated in composite for standard crown dies. Monolithic 1.0-mm (MON) and 2.0-mm CAD/CAM lithium disilicate crowns, the latter with a buccal thin veneer (BTV) of 0.5 mm, were fabricated and then sliding-contact-fatigued (step-stress method) until failure or suspension (n = 18/group). Crack evolution was followed, and fractography of post mortem specimens was performed and compared with that of clinical specimens. Use level probability Weibull calculation (use load = 1,200 N) showed interval overlaps between MON and BTV. There was no significant difference between the Weibull characteristic failure loads of MON and BTV (1,535 N [90% CI 1,354-1,740] and 1,609 N [90% CI 1,512-1,712], respectively), which were significantly higher than that of Y-TZP (370 N [90% CI 322-427]) and comparable with that of MCR (1,304 N [90% CI 1,203-1,414]), validating the study hypothesis. PMID:22205635

  12. Reliability of Reduced-thickness and Thinly Veneered Lithium Disilicate Crowns

    PubMed Central

    Silva, N.R.F.A.; Bonfante, E.A.; Martins, L.M.; Valverde, G.B.; Thompson, V.P.; Ferencz, J.L.; Coelho, P.G.

    2012-01-01

    The present investigation hypothesized that the reliability of reduced-thickness monolithic lithium disilicate crowns is high relative to that of veneered zirconia (Y-TZP) and comparable with that of metal ceramic (MCR) systems. CAD/CAM first mandibular molar full-crown preparations were produced with uniform thicknesses of either 1.0-mm or 2.0-mm occlusal and axial reduction, then replicated in composite for standard crown dies. Monolithic 1.0-mm (MON) and 2.0-mm CAD/CAM lithium disilicate crowns, the latter with a buccal thin veneer (BTV) of 0.5 mm, were fabricated and then sliding-contact-fatigued (step-stress method) until failure or suspension (n = 18/group). Crack evolution was followed, and fractography of post mortem specimens was performed and compared with that of clinical specimens. Use level probability Weibull calculation (use load = 1,200 N) showed interval overlaps between MON and BTV. There was no significant difference between the Weibull characteristic failure loads of MON and BTV (1,535 N [90% CI 1,354–1,740] and 1,609 N [90% CI 1,512–1,712], respectively), which were significantly higher than that of Y-TZP (370 N [90% CI 322–427]) and comparable with that of MCR (1,304 N [90% CI 1,203–1,414]), validating the study hypothesis. PMID:22205635

  13. Dental x-rays

    MedlinePlus

    ... or impacted teeth The presence and extent of dental caries (cavities) Bone damage (such as from periodontitis ) Abscessed ... Dental x-rays can reveal dental cavities (tooth decay) before they ... take yearly bitewings for the early development of cavities.

  14. Comparative study between laser sintering and casting for retention of resin composite veneers to cobalt-chromium alloy.

    PubMed

    Muratomi, Ryuta; Kamada, Kohji; Taira, Yohsuke; Higuchi, Shizuo; Watanabe, Ikuya; Sawase, Takashi

    2013-01-01

    The purpose of this study was to evaluate and compare the bond strengths between resin composite veneer and laser-sintered cobalt-chromium (Co-Cr) alloy with and without retention devices (Laser-R and Laser-N respectively). Cast Co-Cr alloy with and without retention devices (Cast-R and Cast-N respectively) were also prepared for fabrication technique comparison. Disk-shaped Co-Cr alloy specimens were air-abraded with alumina and veneered with a veneering system, Estenia C&B (ES) or Ceramage (CE). After 20,000 thermocycles, tensile testing was performed. Data were analyzed by ANOVA and multiple comparison test. When no retention devices were present, no significant differences were observed between Laser-N/ES and Cast-N/ES, or between Laser- N/CE and Cast-N/CE, but ES exhibited significantly higher bond strength than CE. With retention devices, Laser-R/ES, Cast- R/ES and Laser-R/CE showed no significant differences, and their retention strengths were significantly higher than that of Cast- R/CE. Compared to cast Co-Cr alloy, laser-sintered Co-Cr alloy with retention devices provided better retention durability for resin composite-veneered prostheses. PMID:24240892

  15. 75 FR 28661 - Ceda-Pine Veneer, Inc., a Subsidiary of Excaliber, Inc., Sandpoint, ID; Notice of Negative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-21

    ... FR 7034). Pursuant to 29 CFR 90.18(c,) reconsideration may be granted under the following... determination regarding eligibility to apply for Trade Adjustment Assistance (TAA), applicable to workers and... negative determination of the TAA petition filed on behalf of workers at Ceda-Pine Veneer, Inc.,...

  16. Dental Holography

    NASA Astrophysics Data System (ADS)

    Dirtoft, Ingegerd

    1983-12-01

    Ten years have passed since the first articles appeared in this new field. The qualities of the laser light together with the need of contactless 3-D measurements for different dental purposes seemed to be extremely promising, but still just a few scientists have used the method and mostly for laboratory studies. For some reason there has been a preponderance for orthodontic measurements. This seems to be a bit peculiar from holographic view compared with measurements for engineering purposes, which usually are made on metals. So naturally holography can become a clinical tool for measurements in the field of fixed bridges, removable partial dentures and implants. One of the problems is that the need for holography in dental research must be fulfilled in collaboration with physicists. Only a two-way communication during an entire experiment can balance both technical and odontological demands and thus give practical and clinical important results. The need for an easy way of handling the evaluation to get all required information is another problem and of course the holographic equipment must be converted to a box easy to handle for everyone. At last the position of dental holography today is going to be carefully examined together with an attempt to look into the hopefully exciting and not to utopic future for this research field.

  17. Dental Fear among Medical and Dental Undergraduates

    PubMed Central

    Hakim, H.; Razak, I. A.

    2014-01-01

    Objective. To assess the prevalence and level of dental fear among health related undergraduates and to identify factors causing such fear using Kleinknecht's Dental Fear Survey (DFS) questionnaire. Methods. Kleinknecht's DFS questionnaire was used to assess dental fear and anxiety among the entire enrollment of the medical and dental undergraduates' of the University of Malaya. Results. Overall response rate was 82.2%. Dental students reported higher prevalence of dental fear (96.0% versus 90.4%). However, most of the fear encountered among dental students was in the low fear category as compared to their medical counterpart (69.2 versus 51.2%). Significantly more medical students cancelled dental appointment due to fear compared to dental students (P = 0.004). “Heart beats faster” and “muscle being tensed” were the top two physiological responses experienced by the respondents. “Drill” and “anesthetic needle” were the most fear provoking objects among respondents of both faculties. Conclusion. Dental fear and anxiety are a common problem encountered among medical and dental undergraduates who represent future health care professionals. Also, high level of dental fear and anxiety leads to the avoidance of the dental services. PMID:25386615

  18. Comparative evaluation of fracture resistance of Ceramic Veneer with three different incisal design preparations - An In-vitro Study

    PubMed Central

    Jankar, Ajit S; Kale, Yogesh; Kangane, Suresh; Ambekar, Anand; Sinha, Manish; Chaware, Sachin

    2014-01-01

    Background: Ceramic veneer fracture has occurred mainly at the incisal edge of the veneer because of greater stress. This study compares and evaluates the fracture resistance ceramic veneers with three different incisal preparations. Materials & Methods: 15 human permanent maxillary central incisor extracted were selected which were divided into three groups of 5 each having a different Incial design Preparation. Group 1: No Incisal reduction with facio- incisal bevel, Group 2 : 1 mm incisal reduction with butt joint, Group 3 : 1 mm incisal reduction with 1 mm height of Palatal chamfer. It was found that Group III had greater fracture resistance as compared to Group I and Group II. Group I had least fracture resistance as compared to Group II and III. Group II had greater fracture resistance as compared to Group I but less than Group III. Results: Ceramic veneer with 1mm incisal reduction with 1mm height of palatal chamfer showed highest fracture resistance as compared to 1mm incisal reduction with butt joint and no incisal reduction with facial-incisal bevel, in order to achieve better esthetic and functional results. Conclusion: The palatal chamfer margin results in preservation of some peripheral enamel layer, which eliminates the micro leakage at the palatal margin-restoration interface and also effectively counteracting shear stress. This design provides a definite seat for cementation. How to cite the article: Jankar AS, Kale Y, Kangane S, Ambekar A, Sinha M, Chaware S. Comparative evaluation of fracture resistance of Ceramic Veneer with three different incisal design preparations - An In-vitro Study. J Int Oral Health 2014;6(1):48-54. PMID:24653603

  19. Occupational Health and Safety Issues in Ontario Sawmills and Veneer/Plywood Plants: A Pilot Study

    PubMed Central

    Verma, Dave K.; Demers, Cecil; Shaw, Don; Verma, Paul; Kurtz, Lawrence; Finkelstein, Murray; des Tombe, Karen; Welton, Tom

    2010-01-01

    A pilot study was conducted within the Ontario sawmill and veneer/plywood manufacturing industry. Information was collected by postal questionnaire and observational walk-through surveys. Industrial hygiene walk-through surveys were conducted at 22 work sites, and measurements for wood dust, noise, and bioaerosol were taken. The aim of the study was to obtain data on the current status regarding health and safety characteristics and an estimate of wood dust, noise, and bioaerosol exposures. The occupational exposure to wood dust and noise are similar to what has been reported in this industry in Canada and elsewhere. Airborne wood dust concentration ranged between 0.001 mg/m3 and 4.87 mg/m3 as total dust and noise exposure ranged between 55 and 117 dB(A). The study indicates the need for a more comprehensive industry-wide study of wood dust, noise, and bioaersols. PMID:21253473

  20. Occupational health and safety issues in Ontario sawmills and veneer/plywood plants: a pilot study.

    PubMed

    Verma, Dave K; Demers, Cecil; Shaw, Don; Verma, Paul; Kurtz, Lawrence; Finkelstein, Murray; des Tombe, Karen; Welton, Tom

    2010-01-01

    A pilot study was conducted within the Ontario sawmill and veneer/plywood manufacturing industry. Information was collected by postal questionnaire and observational walk-through surveys. Industrial hygiene walk-through surveys were conducted at 22 work sites, and measurements for wood dust, noise, and bioaerosol were taken. The aim of the study was to obtain data on the current status regarding health and safety characteristics and an estimate of wood dust, noise, and bioaerosol exposures. The occupational exposure to wood dust and noise are similar to what has been reported in this industry in Canada and elsewhere. Airborne wood dust concentration ranged between 0.001 mg/m³ and 4.87 mg/m³ as total dust and noise exposure ranged between 55 and 117 dB(A). The study indicates the need for a more comprehensive industry-wide study of wood dust, noise, and bioaersols. PMID:21253473

  1. Clinical performance of novel-design porcelain veneers for the recovery of coronal volume and length.

    PubMed

    Magne, P; Perroud, R; Hodges, J S; Belser, U C

    2000-10-01

    The present study evaluated the clinical performance of bonded porcelain veneers (PV) restoring substantial coronal volume and length in the anterior dentition. Forty-eight PVs were placed in 16 patients, with systematic coverage and reconstitution of the incisal edge, including well-defined anterior guidance. A standardized protocol comprising diagnostic steps that integrate additive waxups and acrylic mockups was used. PVs were fabricated using feldspathic and low-fusing porcelains in a refractory die technique. Incisal overlaps featured freestanding porcelain spans ranging from 1.5 to 5.5 mm. After a mean clinical service of 4.5 years, 13 clinical parameters for each tooth and 4 parameters that applied to persons were recorded. Permutation tests evaluated the effects of margin location, incisal edge span of porcelain, overbite, opposing contact location, and restoration age on ceramic failure and clinical marginal adaptation and seal. At recall, 100% of the veneers were satisfactory with minor interventions. The effect of slight marginal defects and porcelain cracking was negligible. Biologic, periodontal, and esthetic parameters showed excellent results, which were supported by 100% patient-reported satisfaction. All patients felt comfortable with the newly defined anterior guidance. Aging was negligible, and there were no significant effects of margin location (P > 0.08), incisal edge span of the ceramic, or overbite (P > 0.22) on ceramic failure and marginal performance. Minor alterations of the palatal margin, however, tended to be more frequent compared to facial locations, and were found especially when the opposing tooth contact in centric occlusion was located on the palatal margin (P = 0.028). Bonded ceramic restorations represent a reliable, effective procedure to restore extensive coronal volume and length in the anterior dentition. PMID:11203582

  2. Three years in vivo wear: core-ceramic, veneers, and enamel antagonists

    PubMed Central

    Esquivel-Upshaw, Josephine F.; Rose, William F.; Barrett, Allyson A.; Oliveira, Erica R.; Yang, Mark C.K.; Clark, Arthur E.; Anusavice, Kenneth J.

    2012-01-01

    Objectives Test the hypotheses that there are equivalent wear rates for enamel-versus-enamel and ceramic-versus-enamel, analyzing the in vivo wear of crown ceramics, their natural enamel antagonists, and the corresponding two contralateral teeth; and, that bite force does not correlate with the wear. Methods A controlled, clinical trial was conducted involving patients needing full coverage crowns opposing enamel antagonists. Bite forces were measured using a bilateral gnathodynamometer. Single-unit restorations of metal/ceramic (Argedent 62, Argen Corp/IPS d.SIGN veneer); or, core-ceramic/veneer from either, Empress2/Eris, or e.maxPress core/e.maxCeram glaze (ceramics: Ivoclar Vivadent, USA) were randomly assigned, fabricated and cemented. Impressions were made of the ceramic crowns, as well as each maxillary and mandibular quadrant at one week (baseline) and one, two and three years. Resulting models were scanned (3D laser scanner). Maximum wear was calculated by superimposing baseline with annual images. Results There were a total of thirty-six crowns required for thirty-one patients. Each restoration had three associated enamel teeth; 1) crown, 2) antagonist, 3) contralateral, and 4) contralateral-antagonist. SAS PROC MIXED (α=0.05) indicated no statistical significance for mean maximum wear among crown ceramics, enamel antagonists and contralaterals. However, enamel wear was statistically significant in relation to intraoral location (p=0.04) and among years (p<0.02). Analyzed alone, the enamel contralateral-antagonist exhibited significantly greater wear (p<0.001). Considering all wear sites, there was no correlation with bite force (p=0.15). Significance The ceramics and their antagonists exhibited in vivo wear rates within the range of normal enamel. Future studies should examine the wear implications of the contralateral-antagonist enamel. PMID:22410113

  3. Infant dental care (image)

    MedlinePlus

    ... child to bed with a bottle of milk, juice, or sugar water. As the child grows, establishing proper dental hygiene will promote healthy teeth and gums which are essential to overall good health. Poor dental development, dental disease, and dental trauma ...

  4. Evidence for an extracellular zinc-veneer in rodent brains from experiments with Zn-ionophores and ZnT3 knockouts.

    PubMed

    Nydegger, Irma; Rumschik, Sean M; Zhao, Jinfu; Kay, Alan R

    2012-10-17

    Ionic zinc is found at a high concentration in some glutamatergic vesicles of the mammalian brain. Ionic zinc is also found chelated to macromolecules in the extracellular space, constituting what has been called the "zinc veneer". In this communication we show that the zinc ionophore, pyrithione, can be used to demonstrate the presence of the veneer. Application of pyrithione without added ionic zinc to rodent hippocampal slices mobilizes extracellular zinc, which can be detected intracellularly by the zinc probe FluoZin-3. In addition, we show that ZnT3 null mice, which lack the transporter responsible for stocking synaptic vesicles, nevertheless do have a zinc veneer, albeit diminished compared to wild type animals. The presence of the zinc veneer in ZnT3 null mice may account for the absence of any marked deficit in these animals. PMID:23077720

  5. Dental education in Colombia

    PubMed Central

    Jaramillo, Jorge A.; Pulido, Jairo H. Ternera; Núñez, Jaime A. Castro; Bird, William F.; Komabayashi, Takashi

    2014-01-01

    This article describes Colombia's development of formal dentistry, its dental school system, curriculum, and dental licensure, and current issues in oral health care. In 1969, there were only 4 dental schools in Colombia; at this writing there are 21. Five dental schools are public and the other 16 are private. Nearly all classes are conducted in Spanish. Undergraduate pre-dental coursework is not a prerequisite for dental school in Colombia. To obtain licensure, Colombian dental students must complete 5 years of study in dental school, earn a diploma, and work for the government for 1 year. There are approximately 41,400 dentists in Colombia, and the number is increasing quickly. However, the unemployment rate among dentists is very high, even though graduation from dental school is extremely difficult. Although the 1,100:1 ratio of citizens to dentists is considered satisfactory, access to dental care is limited due to the high rate of poverty. PMID:20339245

  6. A 10-Year Clinical Evaluation of Resin-Bonded Fixed Dental Prostheses on Non-Prepared Teeth.

    PubMed

    Piemjai, Morakot; Özcan, Mutlu; Garcia-Godoy, Franklin; Nakabayashi, Nobuo

    2016-06-01

    This study evaluated the conditions of the non-invasive resin-bonded fixed dental prostheses (FDP) and patient satisfaction up to 10 years of clinical function. A total of 23 patients who required fixed prostheses in the areas of mandibular anterior and premolar, and maxillary anterior region received resin-bonded restorations between 1999-2003. In 13 patients with 14 edentulous areas were restored with an adhesive pontic (natural tooth, acrylic and porcelain). Two indirect proximal veneers using resin composite were placed in each space in 10 patients having 13 edentulous spaces. All prostheses were bonded to the proximal surface of adjacent teeth using resin cement based on 4-META/MMA-TBB. No debonding of proximal veneers but 4 pontic debonding was observed which were rebonded and remained functional until final follow up. The abutments in pontic and proximal veneer groups were free of caries and hypersensitivity. Periodontal health was improved after treatment and was maintained for 10 years except for 4 abutments that still showed some bleeding on probing. Non-invasive resin-bonded FDPs are simple, pain-free, less costly treatment procedures that could provide acceptable clinical longevity with high patient satisfaction. PMID:27424337

  7. Dental stem cell patents.

    PubMed

    Morsczeck, Christian; Frerich, Bernhard; Driemel, Oliver

    2009-01-01

    A complex human tissue harbors stem cells that are responsible for its maintenance or repair. These stem cells have been isolated also from dental tissues such as the periodontal ligament, dental papilla or dental follicle and they may offer novel applications in dentistry. This following review summarizes patents about dental stem cells for dental tissue engineering and considers their value for regenerative dentistry. PMID:19149737

  8. Atypical Forensic Dental Identifications.

    PubMed

    Cardoza, Anthony R; Wood, James D

    2015-06-01

    Forensic dental identification specialists are typically the last conventional option for postmortem identification. Forensic dental identification is most often accomplished by comparing radiographs of the decedent's teeth with the dental radiographs obtained from the dentist of the suspected victim. Unfortunately, antemortem dental radiographs are not always available. When presented with this challenge, the authors of this article have been successful in completing identifications using means other than dental radiographic comparison. PMID:26126345

  9. The effects of residual stress, viscoelastic and thermodynamic parameters on apparent fracture toughness of dental bilayer ceramic composites

    NASA Astrophysics Data System (ADS)

    Taskonak, Burak

    Bilayer dental ceramic composites used for fixed partial dentures are becoming more widely used in dental practices because of their biocompatibility, aesthetic properties, and chemical durability. However, large statistical variations in the strength of ceramics are associated with the structural flaws as a result of processing and complex stress states within the surfaces of the materials because of thermal properties of each layer. In addition, partial delaminations of the veneer layer and connector fractures of bilayer ceramic fixed partial dentures (FPDs) have been observed in a clinical study which is a part of this dissertation. Analysis of fracture surfaces of failed FPDs reveals that such fractures of the veneering ceramic are most likely caused by lateral crack growth. Global residual stresses associated with the coefficient of thermal expansion differences between core and veneering ceramics can cause lateral crack initiation. Also, rapid cooling of bilayer ceramics from the sintering temperature of the glass veneer may not allow the interfacial stresses in the viscoelastic glass to relax to equilibrium values. This can further contribute to the propagation of lateral cracks. Furthermore, local residual stresses that develop in the plastic deformation zone below sharp contact areas on the occlusal surface are another contributor to lateral crack growth. Superposition of global residual stresses and a Boussinesq stress field can incrementally increase the possibility of lateral crack growth. The long-range goals of this study are to critically analyze the lateral crack growth mechanisms associated with residual stresses, to modify residual tensile stress distributions by controlled heat treatment, and to minimize the probability of veneering ceramic fractures. Four approaches were used to accomplish these goals: (1) clinical evaluation of a bilayer ceramic fixed partial denture system; (2) fracture surface analysis of clinically failed FPDs; (3

  10. Dental hyponatraemia.

    PubMed

    Simpson, R M

    2011-08-01

    A 14-year-old girl developed dental pain and was treated for acute infected pulpitis of her right upper lateral incisor with drilling and filling. The pain continued and was helped by analgesia, sucking ice cubes and drinking cold water. Forty-eight hours later, she became confused and disoriented. She started to vomit and complained of headache. Investigations revealed hyponatraemia with normal serum potassium levels and initially normal urinary sodium excretion. Over the next 24 hours, she passed 5.45 L of urine and her serum sodium rose from 125 to 143 mmol/L. Self-induced water intoxication has been described during drinking games and initiation ceremonies, but this would appear to an unusual cause. Conservative management proved successful in allowing this girl to recover without sequelae. PMID:21873727

  11. Ratios of S, Se and Te in the silicate Earth require a volatile-rich late veneer.

    PubMed

    Wang, Zaicong; Becker, Harry

    2013-07-18

    The excess of highly siderophile (iron-loving) elements (HSEs) and the chondritic ratios of most HSEs in the bulk silicate Earth (BSE) may reflect the accretion of a chondritic 'late veneer' of about 0.5 per cent of Earth's mass after core formation. The amount of volatiles contained in the late veneer is a key constraint on the budget and the origin of the volatiles in Earth. At high pressures and temperatures, the moderately volatile chalcogen elements sulphur (S), selenium (Se) and tellurium (Te) are moderately to highly siderophile; thus, if depleted by core formation their mantle abundances should reflect the volatile composition of the late veneer. Here we report ratios and abundances of S, Se and Te in the mantle determined from new isotope dilution data for post-Archaean mantle peridotites. The mean S/Se and Se/Te ratios of mantle lherzolites overlap with CI (Ivuna-type) carbonaceous chondrite values. The Se/Te ratios of ordinary and enstatite chondrites are significantly different. The chalcogen/HSE ratio of the BSE is similar to that of CM (Mighei-type) carbonaceous chondrites, consistent with the view that the HSE signature of the BSE reflects a predominance of slightly volatile-depleted, carbonaceous-chondrite-like material, possibly with a minor proportion of non-chondritic material. Depending on the estimates for the abundances of water and carbon in the BSE, the late veneer may have supplied 20 to 100 per cent of the budget of hydrogen and carbon in the BSE. PMID:23868263

  12. Redistribution of Lunar Polar Water to Mid-latitudes and its Role in Forming an OH veneer - Revisited

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Killen, R. M.; Hurley, D. M.; Hodges, R. R.; Halekas, J. S.; Delory, G. T.

    2012-01-01

    We suggest that energization processes like ion sputtering and impact vaporization can eject/release polar water molecules residing within lunar cold trapped regions with sufficient velocity to allow their redistribution to mid-latitudes. We consider the possibility that these polar-ejected molecules can be an additional (but not dominant) contribution to the water/OH veneer observed as a 3 micron absorption feature at mid-latitudes by Chandrayaan-I, Cassini, and EPOXI. Taking the conservative case that polar water is ejected only from the floor of polar craters with an 0.1 % icy regolith then overall source rates are near 10(exp 18) H20s/s. This outflow amounts to approx 10(exp -7) kg/s of water to be ejected from each pole and is a water source rate that is 10(exp .5 lower than the overall exospheric source rate for all species. Hence, the out-flowing polar water is a perturbation in the overall exosphere composition & dynamics. This polar water 'fountain' model may not fully account for the relatively high concentrations in the mid-latitude water veneer observed in the IR (approx 10-1000 ppm). However, it may account for some part of the veneer. We note that the polar water fountain source rates scale linearly with ice concentration, and larger mass fractions of polar crater water should provide correspondingly larger fractions of water emission out of the poles which then 'spills' on to mid-latitude surfaces.

  13. Effect of intermediate fiber layer on the fracture load and failure mode of maxillary incisors restored with laminate veneers.

    PubMed

    Turkaslan, Suha; Tezvergil-Mutluay, Arzu; Bagis, Bora; Shinya, Akikazu; Vallittu, Pekka K; Lassila, Lippo V

    2008-01-01

    This study evaluated the fracture load and failure mode of various veneer materials cemented with or without the addition of a fiber-reinforced composite (FRC) layer at the adhesive interface. Sixty intact incisors were randomly divided into three groups. Group 1 was fabricated with the heat-press technique (IPS Empress 2); Group 2 with the copy milling technique (ZirkonZahn); and Group 3 with the direct or indirect composite technique (Z250)--and specimens were cemented either with or without FRC at the adhesive interface. The specimens were thermocycled and tested with a universal testing machine. No significant differences in fracture load (p>0.05) were found among the various veneer materials. The addition of FRC at the adhesive layer did not lead to significant differences in the fracture load (p>0.05) but resulted in differences in the failure mode. Laminate veneers made of composite, zirconia, and Empress 2 showed comparable mean fracture loads. However, the use of FRC at the interface changed their failure modes. PMID:18309613

  14. Achievable Convergence Angle and the Effect of Preparation Design on the Clinical Outcome of Full Veneer Crowns in Dogs

    PubMed Central

    Soukup, Jason W.; Snyder, Christopher J.; Karls, Tina L.; Riehl, Jessica

    2012-01-01

    Summary It is widely accepted that the convergence angle of a full veneer crown preparation should be as close to parallel as possible to attain adequate retention/resistance. The shape of the dog’s canine tooth limits the veterinary dentists’ ability to achieve the recommended convergence angle. However, the clinically achievable convergence angle of the canine tooth in dogs has not been evaluated. In addition, the convergence angle and other physical properties of a preparation, such as height and base diameter, have been shown to affect the retention/resistance of full veneer crowns, in vitro. This effect has not been evaluated clinically in the dog. Physical properties of 32 stone dies from full veneer crowns of canine teeth were studied to evaluate the clinically achievable convergence angle and the potential effect physical properties of the preparation had on the clinical outcome of the restoration. The clinically achievable convergence angle was much higher than the current recommendation. There was an association, albeit not statistically significant, between physical properties of a preparation (convergence angle, height, base diameter) and the clinical outcome of the restoration. PMID:21916370

  15. [Dental records and responsibility].

    PubMed

    Brands, W G

    2006-03-01

    Dental records are more than a small part of the bookkeeping. In most dental practises, keeping records is the task of a dental assistant. In civil court, the dentist is in most countries liable for the mistakes of his employees. In disciplinary court however there may be doubt whether the dentist is responsible for the mistakes of his assistant. Contrary to their American colleagues, Dutch dental assistants and dental hygienists cannot be summoned before a disciplinary court. As these para-medics perform more and more dental treatment, independently or after delegation, they should be assigned there own disciplinary responsibility. PMID:16566401

  16. Bond strength of veneer ceramic and zirconia cores with different surface modifications after microwave sintering

    PubMed Central

    Saka, Muhammet

    2013-01-01

    PURPOSE To evaluate the effects of surface treatments on shear bond strength (SBS) between microwave and conventionally sintered zirconia core/veneers. MATERIALS AND METHODS 96 disc shaped Noritake Alliance zirconia specimens were fabricated using YenaDent CAM unit and were divided in 2 groups with respect to microwave or conventional methods (n=48/group). Surface roughness (Ra) evaluation was made with a profilometer on randomly selected microwave (n=10) and conventionally sintered (n=10) cores. Specimens were then assessed into 4 subgroups according to surface treatments applied (n=12/group). Groups for microwave (M) and conventionally (C) sintered core specimens were as follows; MC,CC: untreated (control group), M1,C1:Al2O3 sandblasting, M2,C2:liner, M3,C3:Al2O3 sandblasting followed by liner. Veneer ceramic was fired on zirconia cores and specimens were thermocycled (6000 cycles between 5°-55℃). All specimens were subjected to SBS test using a universal testing machine at 0.5 mm/min, failure were evaluated under an optical microscope. Data were statistically analyzed using Shapiro Wilk, Levene, Post-hoc Tukey HSD and Student's t tests, Two-Way-Variance-Analysis and One-Way-Variance-Analysis (α=.05). RESULTS Conventionally sintered specimens (1.06 ± 0.32 µm) showed rougher surfaces compared to microwave sintered ones (0.76 ± 0.32 µm)(P=.046), however, no correlation was found between SBS and surface roughness (r=-0.109, P=.658). The statistical comparison of the shear bond strengths of C3 and C1 group (P=.015); CC and MC group (P=.004) and C3 and M3 group presented statistically higher (P=.005) values. While adhesive failure was not seen in any of the groups, cohesive and combined patterns were seen in all groups. CONCLUSION Based on the results of this in-vitro study, Al2O3- sandblasting followed by liner application on conventionally sintered zirconia cores may be preferred to enhance bond strength. PMID:24353890

  17. Dental Auxiliary Occupations. Interim Report.

    ERIC Educational Resources Information Center

    Kingston, Richard D.

    As part of a dental auxiliaries project, a Dental Auxiliary National Technical Advisory Committee was established, and its major undertaking was to assist in the development of a functional inventory for each of the three dental auxiliary occupations (dental assisting, dental hygiene, and dental laboratory technology). The analysis consisted of…

  18. Dental education in Malaysia.

    PubMed

    Komabayashi, Takashi; Razak, Abdul Aziz Abdul; Bird, William F

    2007-12-01

    There was only one dental school in Malaysia until 1997 but five new schools have been established since 1998. This review provides information about dental education in Malaysia including; the history of dental education, the current dental school system and curriculum, and dental licensure. There are four public and two private dental schools in Malaysia. High school graduates are required to take the nationwide matriculation entrance examination or the Higher School Certificate (HSC) to apply for a dental degree programme. A five-year dental programme leads to the BDS or the DDS degree. National or state examinations are not required to practise dentistry. Currently, there are approximately 2,500 dentists, with a ratio of 1 dentist for every 10,000 people. PMID:18265775

  19. Dental x-rays

    MedlinePlus

    X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film ... dentist's office. There are many types of dental x-rays. Some are: Bitewing Periapical Palatal (also called occlusal) ...

  20. Dental education in Mexico.

    PubMed

    Masuoka, David; Komabayashi, Takashi; Reyes-Vela, Enrique

    2014-06-01

    The aim of this article is to provide information about dental education in Mexico, including its history, the dental school system, curriculum and dental licensure. In 1977, there were only 59 Mexican dental schools; however, there were 83 schools registered in the last official national count in 2007. Forty-one dental schools are public, and the other 42 are private. Every year the number of private dental schools increases. Admission to dental schools in Mexico requires a high school diploma. All classes are conducted in Spanish. To obtain licensure in Mexico, dental students must complete a 3 to 5-year program plus a year of community service. No formal nationwide standard clinical/didactic curriculum exists in Mexico. There are approximately 153,000 dentists in Mexico, a number that increases each year. The dentist-patient ratio is approximately 1:700. However, the high percentage of inactive licensed dentists in Mexico points to a serious problem. PMID:24984634

  1. American Dental Education Association

    MedlinePlus

    ... work hard to help your students fulfill their dreams, and play a crucial... Learn more Dental School ... Terms of Use | Website Feedback | Website Help ©2016 American Dental Education Association® (ADEA), 655 K Street, NW, ...

  2. Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework

    PubMed Central

    GRANDO, Antônio Francisco; REZENDE, Carlos Eduardo Edwards; SOUSA, Edson Antônio Capello; RUBO, José Henrique

    2014-01-01

    Knowing how stresses are dissipated on the fixed implant-supported complex allows adequate treatment planning and better choice of the materials used for prosthesis fabrication. Objectives The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant. PMID:25025562

  3. DENTAL SCHOOL PLANNING.

    ERIC Educational Resources Information Center

    GALAGAN, DONALD J.

    THIS DISCUSSION PRESENTS A COMPLETE PICTURE OF THE CURRENT STATE OF DENTAL EDUCATION WITH SUGGESTIONS FOR MEETING THE DEMANDS FOR DENTAL STAFF AND FACILITIES. THE AREAS INVESTIGATED ARE (1) OBJECTIVES IN DENTAL EDUCATION--COURSES, TEACHING MODES, INNOVATIONS IN CURRICULUM, COORDINATION OF BASIC AND CLINICAL INSTRUCTION, (2) FACILITY…

  4. Dental Laboratory Technology.

    ERIC Educational Resources Information Center

    Department of the Air Force, Washington, DC.

    The Air Force dental laboratory technology manual is designed as a basic training text as well as a reference source for dental laboratory technicians, a specialty occupation concerned with the design, fabrication, and repair of dental prostheses. Numerous instructive diagrams and photographs are included throughout the manual. The comprehensive…

  5. Perspectives from Dental Research.

    ERIC Educational Resources Information Center

    Baum, Bruce J.

    1996-01-01

    This paper responds to the Institute of Medicine's 1995 report concerning the present status and future needs of dental education in the United States. It examines whether real reform is occurring at the National Institute of Dental Research, within the academic dental community, and within the practicing profession. It concludes that very little…

  6. Dental Manpower Fact Book.

    ERIC Educational Resources Information Center

    Ake, James N.; Johnson, Donald W.

    Statistical data on many aspects of dental and allied dental personnel supply, distribution, characteristics, and education and on certain other aspects of dental services are presented and discussed. The data on dentist supply show the national trend in the supply of active dentists since 1950 and the concurrent changes in dentist-to-population…

  7. Weaker dental enamel explains dental decay.

    PubMed

    Vieira, Alexandre R; Gibson, Carolyn W; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution. PMID:25885796

  8. Description and Documentation of the Dental School Dental Delivery System.

    ERIC Educational Resources Information Center

    Chase, Rosen and Wallace, Inc., Alexandria, VA.

    A study was undertaken to describe and document the dental school dental delivery system using an integrated systems approach. In late 1976 and early 1977, a team of systems analysts and dental consultants visited three dental schools to observe the delivery of dental services and patient flow and to interview administrative staff and faculty.…

  9. An Evaluation of Frangible Materials as Veneers on Vented Structural Member Designs

    SciTech Connect

    Jameson, Kevin Jay

    2015-10-01

    Literature shows there has been extensive research and testing done in the area of wall panels and frangible materials. There is evidence from past research that shows it is possible to vent a structure that has had an accidental internal explosion [1]. The reviewed literature shows that most designs vent the entire wall panel versus a frangible material attached to the wall panel. The frangible material attachment points are important to determine the overall loading of the wall panel structure [2]. The materials used in the reviewed literature were securely attached as well as strong enough to remain intact during the pressure loading to move the entire wall panel. Since the vented wall panel was the weakest part of the overall structure, the other walls of the structure were substantially larger. The structure was usually built from concrete and large amounts of steel with dirt and sand over the top of the structure.The study will be conducted at Sandia National Laboratories located in Albuquerque New Mexico. The skeletal structural design for evaluation is a rectangular frame with a square grid pattern constructed from steel. The skeletal structure has been given to the researcher as a design requirement. The grid pattern will be evaluated strictly on plastic deformation and the loading that is applied from the frangible material. The frangible material tested will either fit into the grid or will be a veneer lightly attached to the structure frame. The frangible material may be required on both sides of the structure to adequately represent the application.

  10. Platinum partitioning between metal and silicate melts: Core formation, late veneer and the nanonuggets issue

    NASA Astrophysics Data System (ADS)

    Médard, Etienne; Schmidt, Max W.; Wälle, Markus; Keller, Nicole S.; Günther, Detlef

    2015-08-01

    High-pressure, high-temperature experiments have been performed at ∼1.2 GPa and 1360-2100 °C to investigate the partitioning of Pt between a silicate melt and a metallic melt. Our experiments indicate that nanonuggets encountered in previous experiments are experimental artifacts, formed at high temperature by oversaturation caused by high oxygen fugacity during the initial stages of an experiment. Experiments at high-acceleration using a centrifuging piston-cylinder show that nanonuggets can be removed by gravity during the experiment. Formation of nanonuggets can also be avoided by using initially reduced starting materials. The presence of iron is also a key element in reducing the formation of nanonuggets. Our nanonugget-free data are broadly consistent with previous nanonuggets-filtered data, and suggest that Pt partitioning becomes independent of oxygen fugacity below an oxygen fugacity of at least IW+2. Pt is thus possibly dissolved as a neutral species (or even an anionic species) at low fO2, instead of the more common Pt2+ species present at higher fO2. Due to low concentration, the nature of this species cannot be determined, but atomic Pt or Pt- are possible options. Under core-formation conditions, Pt partitioning between metal and silicate is mostly independent of oxygen fugacity, silicate melt composition, and pressure. Partition coefficient during core formation can be expressed by the following equation: log DPtMmetal/silicate = 1.0348 + 14698 / T (in weight units). Calculations indicate that the Pt content (and by extension the Highly Siderophile Elements content) of the Earth's mantle cannot be explained by equilibrium partitioning during core formation, requiring further addition of HSE to the mantle. The mass of this late veneer is approximately 0.4% of the total mass of the Earth (or 0.6% of the mass of the mantle).

  11. Influence of Full Veneer Restoration on Fracture Resistance of Three Different Core Materials: An Invitro Study

    PubMed Central

    Manoharan, P.S; Shekhawat, Kuldeep Singh; Deb, Saikat; Chidambaram, S.; Konchada, Jagadish; Venugopal, Nirupa; Vadivel, Harish

    2015-01-01

    Aims and Objectives One of the factor which affects the strength of the tooth restored with core material is the property of the material. In clinical situation all such restored teeth are protected by crowns. This study evaluated the strength of different core materials on a compromised tooth structure after restoration with a crown. Materials and Methods Seventy extracted intact human premolars were collected and mounted within a mould using auto-polymerizing resin. The teeth were divided in-to four groups - A, B, C and D. Each group contained 20 teeth except group A with 10 teeth. All the teeth were prepared for full veneer cast crown. Except for the teeth in group: A) extensive class-I cavities were prepared in the teeth of all the groups and restored with; B) composite resin, 3M EPSE Filtek P60; C) Silver reinforced glass ionomer, SHOFU Hi Dense XP and; (D) Resin reinforced glass ionomer, GC Gold Label light cure GIC. All the teeth were restored with cast-metal alloy and exposed to 1.2 million cycles of cyclic loading in a chewing simulator. Subsequently, the teeth that survived were loaded till fracture in the universal testing machine. Fracture loads and type of fractures were recorded. Results All the specimens survived cyclic loading. The mean fracture strength of the silver reinforced glass ionomer was greater with and without crown (p<0.001). Statistical analysis for the mean fracture load of each specimen showed significant difference between the groups. Conclusion Under the condition of this study, core materials when restored with artificial crown had a significant increase in fracture resistance. PMID:26501004

  12. Influence of resin cement shade on the color and translucency of ceramic veneers

    PubMed Central

    HERNANDES, Daiana Kelly Lopes; ARRAIS, Cesar Augusto Galvão; de LIMA, Erick; CESAR, Paulo Francisco; RODRIGUES, José Augusto

    2016-01-01

    ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C* ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable. PMID:27556211

  13. SEM evaluation of human gingival fibroblasts growth onto CAD/CAM zirconia and veneering ceramic for zirconia

    PubMed Central

    Zizzari, Vincenzo; Borelli, Bruna; De Colli, Marianna; Tumedei, Margherita; Di Iorio, Donato; Zara, Susi; Sorrentino, Roberto; Cataldi, Amelia; Gherlone, Enrico Felice; Zarone, Fernando; Tetè, Stefano

    2013-01-01

    Summary Aim To evaluate the growth of Human Gingival Fibroblasts (HGFs) cultured onto sample discs of CAD/CAM zirconia and veneering ceramic for zirconia by means of Scanning Electron Microscope (SEM) analysis at different experimental times. Methods A total of 26 experimental discs, divided into 2 groups, were used: Group A) CAD/CAM zirconia (3Y-TZP) discs (n=13); Group B) veneering ceramic for zirconia discs (n=13). HGFs were obtained from human gingival biopsies, isolated and placed in culture plates. Subsequently, cells were seeded on experimental discs at 7,5×103/cm2 concentration and cultured for a total of 7 days. Discs were processed for SEM observation at 3h, 24h, 72h and 7 days. Results In Group A, after 3h, HGFs were adherent to the surface and showed a flattened profile. The disc surface covered by HGFs resulted to be wider in Group A than in Group B samples. At SEM observation, after 24h and 72h, differences in cell attachment were slightly noticeable between the groups, with an evident flattening of HGFs on both surfaces. All differences between Group A and group B became less significant after 7 days of culture in vitro. Conclusions SEM analysis of HGFs showed differences in terms of cell adhesion and proliferation, especially in the early hours of culture. Results showed a better adhesion and cell growth in Group A than in Group B, especially up to 72h in vitro. Differences decreased after 7 days, probably because of the rougher surface of CAD/CAM zirconia, promoting better cell adhesion, compared to the smoother surface of veneering ceramic. PMID:24611089

  14. Chemical Compositional Indications of Aqueous Alteration for Whitewater Lake Boxworks, Veneers and Veins at Cape York, Mars

    NASA Astrophysics Data System (ADS)

    Clark, Benton; Gellert, R.; Squyres, S.; Arvidson, R.; Yen, A.; Rice, J.; Athena Science Team

    2013-10-01

    An area of partially-veneered, flat-lying rocks which also includes boxwork and linear veins contains a variety of compositions which are each indicative of minor to major aqueous alteration processes in the Cape York rim of Endeavour Crater. As analyzed by APXS x-ray fluorescence spectroscopy, the sets of unique elemental compositions correspond variously to Al-Si rich clays in boxwork veins, with Fe- and Cl-enriched salt veneers (Esperance samples); swarms of Ca sulfate veins (Ortiz samples); and, as indicated by remote sensing, mafic smectite alteration products in veneers (Chelmsford covering Azilda samples). Multiple offset analyses by APXS reveal clear trends and associations of certain elements, allowing inferences of mineralogies. In contrast to the acidic environment deduced for the genesis of the multiple-sulfate Burns formation sediments and shallow ferric-rich sulfate deposits beneath soils, these alteration products formed at more near-neutral pH, often with major chemical segregations and requiring high water-rock ratios comparable to a wide range of eminently habitable terrestrial environments. Several of these compositions are also rated high with respect to their potential for preservation of organic materials and biomarkers. Within distances of just tens of meters inside this so-called Whitewater Lake unit, this broad diversity exemplifies the tantalizing opportunities as well as challenges for future sample return missions to the red planet, which in this case could also be expanded to include nearby samples of Burns Fm sandstones, hematite concretions, light-toned spherules (Kirkwood), large gypsum veins (Homestake), martian global soils and surface dust.

  15. Randomized Clinical Trial of Implant-Supported Ceramic-Ceramic and Metal-Ceramic Fixed Dental Prostheses: Preliminary Results

    PubMed Central

    Esquivel-Upshaw, Josephine F.; Clark, Arthur E.; Shuster, Jonathan J.; Anusavice, Kenneth J.

    2013-01-01

    Purpose The aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52–75 years) were recruited for the study to receive a 3-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A. Material: ceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality. Results Recall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher’s exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure

  16. Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements

    PubMed Central

    Cho, Seok-Hwan; Lopez, Arnaldo; Berzins, David W.; Prasad, Soni; Ahn, Kwang Woo

    2015-01-01

    Aim This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements. Materials and Methods A total of 80 ceramic veneer discs were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These discs were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into 4 subgroups, based on ceramic disc thickness (0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm2) with respect to microhardness and degree of conversion was statistically evaluated by using ANOVA. Results For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (P<.05). For the MH values between LC and DC resin cement groups, there was statistically significant difference (P<.05); overall, the MH values of LC resin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (P<.05). However, among the LC subgroups, there was no statistically significant difference among them (P >.05). Conclusion The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup. Clinical Significance While clinically adequate polymerization of LC resin cement can be achieved

  17. Redistribution of Lunar Polar Water to Mid-latitudes and Its Role in Forming an OH Veneer

    NASA Technical Reports Server (NTRS)

    Farrell, William M.; Hurley, D. M.; Hodges, R. R.; Killen, R. M.; Halekas, J. S.; Zimmerman, M. I.; Delory, G. T.

    2013-01-01

    We suggest that energization processes like ion sputtering and impact vaporization can eject/release polar water molecules residing within cold trapped regions with sufficient velocity to allow their redistribution to mid-latitudes. We consider the possibility that these polar-ejected molecules can contribution to the water/OH veneer observed as a 3 micrometer IR absorption feature at mid-latitudes by Chandrayaan-1, Cassini, and EPOXI. We find this source cannot fully account for the observed IR feature, but could be a low intensity additional source.

  18. Digital Smile Design concept delineates the final potential result of crown lengthening and porcelain veneers to correct a gummy smile.

    PubMed

    Trushkowsky, Richard; Arias, David Montalvo; David, Steven

    2016-01-01

    Prior to initiating any treatment, it is necessary to visualize the desired outcomes. It then becomes possible to formulate the steps required to achieve this result. Digital Smile Design (DSD) utilizes patient input and information gathered through diagnostic procedures to create an esthetic treatment scheme. In the case presented here, the NYUCD Esthetic Evaluation Form, intraoral and extraoral photographs, mounted diagnostic casts, physical examination, and radiographs were the diagnostic modalities. The gathered information served as a starting point for a wax-up and intraoral mock-up. This case report demonstrates how the DSD served as a template for crown lengthening procedures and design of the final porcelain veneer restorations. PMID:27433549

  19. Employment of Dental Hygienists as Dental Educators.

    ERIC Educational Resources Information Center

    Fong, Cynthia; Odrich, Johanna

    1987-01-01

    A study of the use of dental hygienists to teach periodontics, preventive dentistry, community dentistry, and public health courses looked at employment patterns and practices and the qualifications of the teachers. (MSE)

  20. Meeting Dental Health Needs Through Dental Education

    ERIC Educational Resources Information Center

    Morris, Alvin L.

    1972-01-01

    Dental health needs of the country cannot be met through education of more dentists. Rather, we must educate auxiliaries to perform many of the intraoral procedures now regarded the sole responsibility of dentists. (SB)

  1. Influence of the fabrication process on the in vitro performance of fixed dental prostheses with zirconia substructures.

    PubMed

    Rosentritt, Martin; Kolbeck, Carola; Handel, Gerhard; Schneider-Feyrer, Sibylle; Behr, Michael

    2011-12-01

    Chipping of the applied veneering ceramic is reported to be a main clinical failure type of computer-aided design/computer-aided manufacturing- or manually copy-milled zirconia restorations. The aim of this in vitro study was to investigate whether different substructure designs and veneering processes done by different dental technicians do significantly influence chipping in zirconia-based all-ceramic fixed dental prostheses during simulated oral service. Five groups (n = 8 per group) of three-unit zirconia substructures were fabricated in three different laboratories using copy-milling technique. Three series were veneered with identical porcelain (groups 1-3) and one with a second different porcelain (group 4). The fifth group was milled to final contour design without veneering. Dimensions of the connector areas were determined. All fixed partial dentures (FPDs) were adhesively boned on human teeth and thermally cycled and mechanically loaded (1.2 × 10(6) × 50 N; 6,000 × 5°C/55°C) using human antagonists. Restorations were monitored during thermal cycling and mechanical loading (TCML). FPDs which survived were loaded to fracture. FPDs which failed during TCML were investigated with fractographic means. During TCML, chipping took place in groups 1 (two times), 2 (four times) and 3 (five times) (Table 1). Chipping areas varied between 2.3 mm(2) (group 3) and 58.7 mm(2) (group 2). Groups 4 and 5 provided no failures during TCML. Failure in all cases started from contact points, where superficial wear and disruption of the porcelain were found. No significant correlation could be determined between connector thickness and number of failures. Median fracture results varied between 1,011 N (group 3) and 2,126 N (group 2). The results show the necessity of considering individual design and manufacturing of restorations as well as contact situation. Advanced technical training on zirconia-based restorations is recommended. PMID:20922439

  2. Dental Implant Systems

    PubMed Central

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  3. Fractographic study of the behavior of different ceramic veneers on full coverage crowns in relation to supporting core materials

    PubMed Central

    Agustín-Panadero, Rubén; Román-Rodriguez, Juan L.; Solá-Ruíz, María F.; Granell-Ruíz, María; Fons-Font, Antonio

    2013-01-01

    Objectives: To observe porcelain veneer behavior of zirconia and metal-ceramic full coverage crowns when subjected to compression testing, comparing zirconia cores to metal cores. Study Design: The porcelain fracture surfaces of 120 full coverage crowns (60 with a metal core and 60 with a zirconia core) subjected to static load (compression) testing were analyzed. Image analysis was performed using macroscopic processing with 8x and 12x enlargement. Five samples from each group were prepared and underwent scanning electron microscope (SEM) analysis in order to make a fractographic study of fracture propagation in the contact area and composition analysis in the most significant areas of the specimen. Results: Statistically significant differences in fracture type (cohesive or adhesive) were found between the metal-ceramic and zirconia groups: the incidence of adhesive fracture was seen to be greater in metal-ceramic groups (92%) and cohesive fracture was more frequent in zirconium oxide groups (72%). The fracture propagation pattern was on the periphery of the contact area in the full coverage crown restorations selected for fractographic study. Conclusions: The greater frequency of cohesive fracture in restorations with zirconia cores indicates that their behavior is inadequate compared to metal-ceramic restorations and that further research is needed to improve their clinical performance. Key words:Zirconia, zirconium oxide, fractography, composition, porcelain veneers, fracture, cohesive, adhesive. PMID:24455092

  4. Widespread evidence for a late veneer on the terrestrial planets and planetisimals

    NASA Astrophysics Data System (ADS)

    Dale, C. W.; Burton, K.; Pearson, G.; Greenwood, R. C.

    2010-12-01

    Growth of the Earth from smaller planetisimals resulted in substantial partitioning of the iron-loving (siderophile) into the metallic core. However, some of the most highly siderophile elements in Earth’s silicate mantle are present in much greater concentrations than expected, even for high-pressure equilibration in a deep ‘magma ocean’ [1], and in broadly chondritic proportions. Consequently, it is often assumed that the highly siderophile elements require the late addition of extraterrestrial material (the so called ‘late veneer’) to the mantle after core formation was complete. Core formation on smaller asteroidal bodies cannot have been affected by high-pressure equilibration, and Hf-W chronology suggests that core formation was rapid [2] and, during global scale melting, was likely highly efficient [3]. This study presents new HSE abundance and 187Os/188Os isotope data for basaltic meteorites, the HEDs (Howardites, Eucrites and Diogenites thought to sample the asteroid 4 Vesta), anomalous Eucrites and Angrites (considered to be from distinct parent bodies) and SNCs (thought to be from Mars). The results show that these igneous meteorites all formed from mantle sources that possessed broadly chondritic (i.e. primitive solar system) inter-element ratios and Os isotope compositions, inconsistent with equilibrium partitioning of the PGE. Furthermore, there is a simple relationship where predicted mantle HSE concentrations are linked to the size of the parent body, and so Vesta (like the Moon [4]) has much lower HSE concentrations than Earth or Mars. These data can be most readily explained by the late addition of a chondritic meteorite flux to the silicate mantles of all these bodies, after core formation was complete, and suggests that the addition of a late veneer is a general feature of planetary accretion in the inner solar system, rather than being a unique temporal event that only affected the Earth. [1] Wood, B.J., Walter, M.J. & Wade, J. (2006

  5. A modified technique on the reattachment of permanent tooth fragments following dental trauma. Case report.

    PubMed

    Arapostathis, Konstantinos; Arhakis, Aristidis; Kalfas, Sotiris

    2005-01-01

    Fractured anterior teeth can be restored by adhesive bonding of the fractured fragment to the remaining tooth structure. One of the major challenges for the practitioner treating traumatized anterior teeth with immediate fragment reattachment is disguising the fracture line, through the correct use of masking and restorative resins to make the restorations imperceptible to the eye as well as improve the retention of the restoration. This paper discusses a modified technique for reattaching a permanent tooth fragment following dental trauma. The initial procedure involved simple reattachment using light cured composite resin between the fragment and the remnant part of the tooth, without additional preparation. The surplus resin was spread across it in an attempt to optimize marginal seal and improve the aesthetics of the restoration. Finally, after taking into account the occlusion, the lingual surfaces of the teeth were veneered with microfilled composite to improve the retention of the reattached fragments. PMID:16302596

  6. 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.

  7. Education About Dental Hygienists' Roles in Public Dental Prevention Programs: Dental and Dental Hygiene Students' and Faculty Members' and Dental Hygienists' Perspectives.

    PubMed

    Pervez, Anushey; Kinney, Janet S; Gwozdek, Anne; Farrell, Christine M; Inglehart, Marita R

    2016-09-01

    In 2005, Public Act No. 161 (PA 161) was passed in Michigan, allowing dental hygienists to practice in approved public dental prevention programs to provide services for underserved populations while utilizing a collaborative agreement with a supervising dentist. The aims of this study were to assess how well dental and dental hygiene students and faculty members and practicing dental hygienists have been educated about PA 161, what attitudes and knowledge about the act they have, and how interested they are in additional education about it. University of Michigan dental and dental hygiene students and faculty members, students in other Michigan dental hygiene programs, and dental hygienists in the state were surveyed. Respondents (response rate) were 160 dental students (50%), 63 dental hygiene students (82%), 30 dental faculty members (26%), and 12 dental hygiene faculty members (52%) at the University of Michigan; 143 dental hygiene students in other programs (20%); and 95 members of the Michigan Dental Hygienists' Association (10%). The results showed that the dental students were less educated about PA 161 than the dental hygiene students, and the dental faculty members were less informed than the dental hygiene faculty members and dental hygienists. Responding dental hygiene faculty members and dental hygienists had more positive attitudes about PA 161 than did the students and dental faculty members. Most of the dental hygiene faculty members and dental hygienists knew a person providing services in a PA 161 program. Most dental hygiene students, faculty members, and dental hygienists wanted more education about PA 161. Overall, the better educated about the program the respondents were, the more positive their attitudes, and the more interested they were in learning more. PMID:27587574

  8. Special cluster issue on tribocorrosion of dental materials

    NASA Astrophysics Data System (ADS)

    Mathew, Mathew T.; Stack, Margaret M.

    2013-10-01

    Tribocorrosion affects all walks of life from oil and gas conversion to biomedical materials. Wear can interact with corrosion to enhance it or impede it; conversely, corrosion can enhance or impede wear. The understanding of the interactions between physical and chemical phenomena has been greatly assisted by electrochemical and microscopic techniques. In dentistry, it is well recognized that erosion due to dissolution (a term physicists use to denote wear) of enamel can result in tooth decay; however, the effects of the oral environment, i.e. pH levels, electrochemical potential and any interactions due to the forces involved in chewing are not well understood. This special cluster issue includes investigations on the fundamentals of wear-corrosion interactions involved in simulated oral environments, including candidate dental implant and veneer materials. The issue commences with a fundamental study of titanium implants and this is followed by an analysis of the behaviour of commonly used temporomandibular devices in a synovial fluid-like environment. The analysis of tribocorrosion mechanisms of Ti6Al4V biomedical alloys in artificial saliva with different pHs is addressed and is followed by a paper on fretting wear, on hydroxyapatite-titanium composites in simulated body fluid, supplemented with protein (bovine serum albumin). The effects of acid treatments on tooth enamel, and as a surface engineering technique for dental implants, are investigated in two further contributions. An analysis of the physiological parameters of intraoral wear is addressed; this is followed by a study of candidate dental materials in common beverages such as tea and coffee with varying acidity and viscosity and the use of wear maps to identify the safety zones for prediction of material degradation in such conditions. Hence, the special cluster issue consists of a range of tribocorrosion contributions involving many aspects of dental tribocorrosion, from analysis of physiological

  9. In vitro evaluation of the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with composite fillings after cyclic loading

    PubMed Central

    Sadighpour, Leyla; Fallahi Sichani, Babak; Kharazi Fard, Mohamd Javad

    2014-01-01

    PURPOSE There is insufficient data regarding the durability of porcelain laminate veneers bonded to existing composite fillings. The aim of the present study was to evaluate the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with existing composite fillings. MATERIALS AND METHODS Thirty maxillary central incisors were divided into three groups (for each group, n=10): intact teeth (NP), teeth with class III composite fillings (C3) and teeth with class IV cavities (C4). Porcelain laminate veneers were made using IPS-Empress ceramic and bonded with Panavia F2 resin cement. The microleakage of all of the specimens was tested before and after cyclic loading (1 × 106 cycles, 1.2 Hz). The fracture resistance values (N) were measured using a universal testing machine, and the mode of failure was also examined. The statistical analyses were performed using one-way ANOVA and Tukey post hoc tests (α=.05). RESULTS There was a significant difference in the mean microleakage of group C4 compared with group NT (P=.013). There was no significant difference in the fracture loads among the groups. CONCLUSION The microleakage and failure loads of porcelain laminate veneers bonded to intact teeth and teeth with standard class III composite fillings were not significantly different. PMID:25177471

  10. Dental Charting. Student's Manual.

    ERIC Educational Resources Information Center

    Weaver, Trudy Karlene; Apfel, Maura

    This manual is part of a series dealing with skills and information needed by students in dental assisting. The individualized student materials are suitable for classroom, laboratory, or cooperative training programs. This student manual contains four units covering the following topics: dental anatomical terminology; tooth numbering systems;…

  11. Dental Laboratory Technician.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of dental laboratory technician, lists technical competencies and competency builders for 13 units pertinent to the health technologies cluster in general and 8 units to the occupation of dental laboratory technician. The following skill areas…

  12. Dental Assisting Program Guide.

    ERIC Educational Resources Information Center

    Georgia Univ., Athens. Dept. of Vocational Education.

    This program guide contains the standard dental assisting curriculum for technical institutes in Georgia. The curriculum encompasses the minimum competencies required for entry-level dental assistants, and includes job skills in the technical areas of preventive dentistry; four-handed dentistry; chairside assisting with emphasis in diagnostics,…

  13. Dental Fear Among University Employees: Implications for Dental Education.

    ERIC Educational Resources Information Center

    Kaakko, Tarja; Milgrom, Peter; Coldwell, Susan E.; Getz, Tracy; Weinstein, Philip; Ramsay, Douglas S.

    1998-01-01

    A survey of 270 University of Washington permanent employees who were potential candidates for teaching clinics, found dental anxiety prevalent, correlating with poorer perceived dental health, longer intervals between dental appointments, higher frequency of past fear behaviors, more physical symptoms during last dental injection, and more…

  14. The future dental workforce?

    PubMed

    Gallagher, J E; Wilson, N H F

    2009-02-28

    The Editor-in-Chief of the BDJ has previously raised important questions about dental workforce planning and the implications for dental graduates of recent changes and pressures. It is now time to revisit this issue. Much has changed since the last workforce review in England and Wales, and the rate of change is in all probability set to increase. First, at the time of writing this paper the momentous step of including dental care professionals (DCPs) on General Dental Council (GDC) registers in the United Kingdom has recently been completed. Second, the Scope of Practice of all dental professionals has been under consultation by the General Dental Council, and research evidence suggests that greater use should be made of skill-mix in the dental team. Third, within England, Lord Darzi has just published the 'Final Report of the NHS Next Stage Review', which emphasises 'quality care' and 'team-working' as key features of healthcare; this report was accompanied by an important document entitled 'A High Quality Workforce', in which plans for local workforce planning within the NHS are outlined, placing responsibilities at national, local and regional levels. Fourth, policy makers across the UK are wrestling with addressing oral health needs, promoting health and facilitating access to dental care, all of which have implications for the nature and shape of the dental workforce. Fifth, with the impact of globalisation and European policies we are net gainers of dentists as well as having more in training. Sixth, although there have been reviews and policy initiatives by regulatory, professional and other bodies in support of shaping the dental workforce, there has been little serious consideration of skill-mix and funding mechanisms to encourage team-working. Together, these events demand that we enter a fresh debate on the future dental workforce which should extend beyond professional and national boundaries and inform workforce planning. This debate is of great

  15. Minimally invasive prosthetic procedures in the rehabilitation of a bulimic patient affected by dental erosion

    PubMed Central

    Derchi, Giacomo; Peñarrocha, David; Barone, Antonio; Covani, Ugo

    2015-01-01

    The population affected by dental erosion due to bulimia is generally very young. This population group has a high aesthetic requirement; the dentition in these patients is severely damaged, especially in the anterior maxillary quadrant. In terms of treatment, it is still controversial whether an adhesive rehabilitation is preferable to a longer-lasting but more aggressive conventional treatment, such as full-crown coverage of the majority of teeth. This case report describes the prosthetic rehabilitation of a young female patient previously affected by bulimia nervosa and presenting erosion of the maxillary teeth. The prosthetic rehabilitation was performed through indirect adhesive restorations of the anterior teeth and direct restorations of the posterior teeth. A clinical follow-up after 4 years showed that the occlusion remained satisfactorily restored. Posterior direct composite resin restorations and anterior indirect adhesive composite restorations proved to be an effective time and money-saving procedure to rehabilitate patients affected by dental erosion. Adhesive rehabilitation provides a functional and good aesthetic result while preserving tooth structure. Key words:Bulimia, dental erosion, composite resin, veneers. PMID:25810832

  16. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly

    PubMed Central

    Lu, Xiaoli; Xia, Yang; Liu, Mei; Qian, Yunzhu; Zhou, Xuefeng; Gu, Ning; Zhang, Feimin

    2012-01-01

    To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride)] and anionic [poly(sodium 4-styrenesulfonate)] polymers to improve the dispersion and adsorption of positively charged nano-ZrO2 (zirconia) as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO2. To determine the optimum addition levels for nano-ZrO2, ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO2 were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO2 resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P < 0.05). Our results show that diatomite-based nanocomposite ceramics are good potential candidates for ceramic-based dental materials. PMID:22619551

  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. Health Instruction Packages: Permanent Teeth, Dental Deposits, and Dental Instruments. Dientes Permanentes, Depositos Dentales y Instrumentos Dentales.

    ERIC Educational Resources Information Center

    Lind, Patricia; Germano, Catherine

    These five learning modules use text interspersed with illustrations and reinforcement exercises to instruct dental aide and dental hygiene students about jaw bones and gums, dental deposits, and dental instruments. The first four modules were prepared by Patricia Lind in both Spanish and English. "The Gum and Bone of Permanent Teeth" ("La Encia y…

  19. Effect of veneer side wettability on bonding quality of Eucalyptus globulus plywoods prepared using a tannin-phenol-formaldehyde adhesive.

    PubMed

    Vázquez, G; González-Alvarez, J; López-Suevos, F; Antorrena, G

    2003-05-01

    The influence of rotary peeling on the different behaviour of tight and loose sides of Eucalyptus globulus veneers has been studied. The presence of lathe checks on the loose sides favours wettability, the contact angle decreasing more rapidly on these sides than on tight sides. Additionally, pine bark tannins improved wettability due to their surfactant character. Bonding quality tests carried out on plywoods prepared using a tannin-phenol-formaldehyde adhesive showed that fracture almost invariably occurred in a glue line with at least one loose side, where wood failure appeared. This behaviour, confirmed by analysing the glue lines by means of fluorescence microscopy, was due to the large surface alterations of the loose sides which reduced mechanical strength but allowed greater penetration of the adhesive giving rise to high wood failure. PMID:12507878

  20. 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

  1. Comparative study of the shear bond strength of various veneering materials on grade II commercially pure titanium

    PubMed Central

    Lee, Eun-Young; Jun, Sul-Gi; Wright, Robert F.

    2015-01-01

    PURPOSE To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti). MATERIALS AND METHODS Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in 5-55℃ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test. RESULTS The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 (12.11 ± 4.44 MPa); Ti-Triceram (11.09 ± 1.66 MPa); Ti-Sinfony (4.32 ± 0.64 MPa). All of these experimental groups showed lower shear bond strength than the control group (16.14 ± 1.89 MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures. CONCLUSION The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy. PMID:25722841

  2. Fracture analysis of randomized implant-supported fixed dental prostheses

    PubMed Central

    Esquivel-Upshaw, Josephine F.; Mehler, Alex; Clark, Arthur E.; Neal, Dan; Anusavice, Kenneth J.

    2014-01-01

    Objective Fractures of posterior fixed dental all-ceramic prostheses can be caused by one or more factors including prosthesis design, flaw distribution, direction and magnitude of occlusal loading, and nature of supporting infrastructure (tooth root/implant), and presence of adjacent teeth. This clinical study of implant-supported, all-ceramic fixed dental prostheses, determined the effects of (1) presence of a tooth distal to the most distal retainer; (2) prosthesis loading either along the non-load bearing or load bearing areas; (3) presence of excursive contacts or maximum intercuspation contacts in the prosthesis; and (4) magnitude of bite force on the occurrence of veneer ceramic fracture. Methods 89 implant-supported FDPs were randomized as either a three-unit posterior metal-ceramic (Au-Pd-Ag alloy and InLine POM, Ivoclar, Vivadent) FDP or a ceramic-ceramic (ZirCAD and ZirPress, Ivoclar, Vivadent) FDP. Two implants (Osseospeed, Dentsply) and custom abutments (Atlantis, Dentsply) supported these FDPs, which were cemented with resin cement (RelyX Universal Cement). Baseline photographs were made with markings of teeth from maximum intercuspation (MI) and excursive function. Patients were recalled at 6 months and 1 to 3 years. Fractures were observed, their locations recorded, and images compared with baseline photographs of occlusal contacts. Conclusion No significant relationship exists between the occurrence of fracture and: (1) the magnitude of bite force; (2) a tooth distal to the most distal retainer; and (3) contacts in load-bearing or non-load-bearing areas. However, there was a significantly higher likelihood of fracture in areas with MI contacts only. Clinical Significance This clinical study demonstrates that there is a need to evaluate occlusion differently with implant-supported prostheses than with natural tooth supported prostheses because of the absence of a periodontal ligament. Implant supported prostheses should have minimal occlusion and

  3. American Dental Association

    MedlinePlus

    ... Oral Health Topics ADVERTISEMENT Advocacy Advocacy Advocacy Issues Health Care Reform ADA Positions, Policies and Statements Legal Advocacy and ... Children's Dental Health Month ADA Seal of Acceptance Fluoride in Water Advocating for the Public Prevention Summit ...

  4. Dental care - child

    MedlinePlus

    ... dental exams, and getting necessary treatments such as fluoride, extractions, fillings, or braces and other orthodontics. ... provider if your infant needs to take oral fluoride . THE FIRST TRIP TO THE DENTIST Your child's ...

  5. Complications of dental surgery.

    PubMed

    Lillich, J D

    1998-08-01

    Both retrospective data and clinical experience indicate that complications of dental surgery are occasionally encountered and, to some extent, are inevitable. Many of the reported complications related to dental surgery such as incomplete removal of diseased teeth or removal of the wrong tooth can be avoided with sound preoperative planning and intraoperative technique. Diseased teeth should be properly identified prior to and during surgery. In addition, complete removal of the diseased tooth must be performed. Use of intraoperative radiographic examination to confirm the location of the diseased tooth and to document its removal cannot be overemphasized. Iatrogenic fracture of the maxillary or mandibular alveolar walls or palatine bone can be avoided by proper placement of the dental punch. The chances of developing incisional drainage or secondary sinusitis can be reduced by use of appropriate systemic antibiotics. These factors should guide the surgical approach to dental surgery to reduce the likelihood of developing common complications. PMID:9742671

  6. Infant dental care (image)

    MedlinePlus

    Even though newborns and infants do not have teeth, care of the mouth and gums is important. ... sugar water. As the child grows, establishing proper dental hygiene will promote healthy teeth and gums which ...

  7. Dental mesenchymal stem cells.

    PubMed

    Sharpe, Paul T

    2016-07-01

    Mammalian teeth harbour mesenchymal stem cells (MSCs), which contribute to tooth growth and repair. These dental MSCs possess many in vitro features of bone marrow-derived MSCs, including clonogenicity, expression of certain markers, and following stimulation, differentiation into cells that have the characteristics of osteoblasts, chondrocytes and adipocytes. Teeth and their support tissues provide not only an easily accessible source of MSCs but also a tractable model system to study their function and properties in vivo In addition, the accessibility of teeth together with their clinical relevance provides a valuable opportunity to test stem cell-based treatments for dental disorders. This Review outlines some recent discoveries in dental MSC function and behaviour and discusses how these and other advances are paving the way for the development of new biologically based dental therapies. PMID:27381225

  8. Glossary of Dental Terms

    MedlinePlus

    ... geta poker friv Home InfoBites Find an AGD Dentist Your Family's Oral Health About the AGD Dental ... and shape of teeth performed by a general dentist | More Edentulous having lost most or all of ...

  9. Dental care - child

    MedlinePlus

    ... Cantor A, Zakher B, et al. Preventing dental caries in children <5 years: systematic review updating USPSTF ... nih.gov/pubmed/15606059 . Ng MW. Early childhood caries: risk-based disease prevention and management. Dent Clin ...

  10. Dental Care in Pregnancy

    MedlinePlus

    ... for you and your baby and contain less sugar that can damage your teeth. Water or low-fat milk hydrates you and contains little or no sugar. For More Information American Dental Association: Pregnancy http : / / ...

  11. Portable Dental System

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Portable dental system provides dental care in isolated communities. System includes a patient's chair and a dentist's stool, an X-ray machine and a power unit, all of which fold into compact packages. A large yellow "pumpkin" is a collapsible compressed air tank. Portable system has been used successfully in South America in out of the way communities with this back-packable system, and in American nursing homes. This product is no longer manufactured.

  12. Dental (Odontogenic) Pain

    PubMed Central

    Renton, Tara

    2011-01-01

    This article provides a simple overview of acute trigeminal pain for the non dentist. This article does not cover oral mucosal diseases (vesiculobullous disorders) that may cause acute pain. Dental pain is the most common in this group and it can present in several different ways. Of particular interest for is that dental pain can mimic both trigeminal neuralgia and other chronic trigeminal pain disorders. It is crucial to exclude these disorders whilst managing patients with chronic trigeminal pain. PMID:26527224

  13. Saliva and dental erosion

    PubMed Central

    BUZALAF, Marília Afonso Rabelo; HANNAS, Angélicas Reis; KATO, Melissa Thiemi

    2012-01-01

    Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear. Objective This review discusses the role of salivary factors on the development of dental erosion. Material and Methods A search was undertaken on MEDLINE website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party. Results Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion. Conclusions Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects. PMID:23138733

  14. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following...

  15. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following...

  16. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following...

  17. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following...

  18. 42 CFR Appendix G to Part 75 - Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography G Appendix G to Part 75 Public Health PUBLIC HEALTH SERVICE...—Standards for Licensing Dental Hygienists and Dental Assistants in Dental Radiography The following...

  19. Dental fitness classification in the Canadian forces.

    PubMed

    Groves, Richard R

    2008-01-01

    The Canadian Forces Dental Services utilizes a dental classification system to identify those military members dentally fit for an overseas deployment where dental resources may be limited. Although the Canadian Forces Dental Services dental classification system is based on NATO standards, it differs slightly from the dental classification systems of other NATO country dental services. Data collected by dental teams on overseas deployments indicate a low rate of emergency dental visits by Canadian Forces members who were screened as dentally fit to deploy. PMID:18277717

  20. Influence of dental materials on dental MRI

    PubMed Central

    Tymofiyeva, O; Vaegler, S; Rottner, K; Boldt, J; Hopfgartner, AJ; Proff, PC; Richter, E-J; Jakob, PM

    2013-01-01

    Objectives: To investigate the potential influence of standard dental materials on dental MRI (dMRI) by estimating the magnetic susceptibility with the help of the MRI-based geometric distortion method and to classify the materials from the standpoint of dMRI. Methods: A series of standard dental materials was studied on a 1.5 T MRI system using spin echo and gradient echo pulse sequences and their magnetic susceptibility was estimated using the geometric method. Measurements on samples of dental materials were supported by in vivo examples obtained in dedicated dMRI procedures. Results: The tested materials showed a range of distortion degrees. The following materials were classified as fully compatible materials that can be present even in the tooth of interest: the resin-based sealer AH Plus® (Dentsply, Maillefer, Germany), glass ionomer cement, gutta-percha, zirconium dioxide and composites from one of the tested manufacturers. Interestingly, composites provided by the other manufacturer caused relatively strong distortions and were therefore classified as compatible I, along with amalgam, gold alloy, gold–ceramic crowns, titanium alloy and NiTi orthodontic wires. Materials, the magnetic susceptibility of which differed from that of water by more than 200 ppm, were classified as non-compatible materials that should not be present in the patient’s mouth for any dMRI applications. They included stainless steel orthodontic appliances and CoCr. Conclusions: A classification of the materials that complies with the standard grouping of materials according to their magnetic susceptibility was proposed and adopted for the purposes of dMRI. The proposed classification can serve as a guideline in future dMRI research. PMID:23610088

  1. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A dental... and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam...

  2. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A dental... and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam...

  3. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A dental... and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam...

  4. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A dental... and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam...

  5. 21 CFR 872.3100 - Dental amalgamator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental amalgamator. 872.3100 Section 872.3100 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3100 Dental amalgamator. (a) Identification. A dental... and dental alloy particles, such as silver, tin, zinc, and copper. The mixed dental amalgam...

  6. Influence of a thin veneer of low-hydraulic-conductivity sediment on modelled exchange between river water and groundwater in response to induced infiltration

    USGS Publications Warehouse

    Rosenberry, D.O.; Healy, R.W.

    2012-01-01

    A thin layer of fine-grained sediment commonly is deposited at the sediment-water interface of streams and rivers during low-flow conditions, and may hinder exchange at the sediment-water interface similar to that observed at many riverbank-filtration (RBF) sites. Results from a numerical groundwater-flow model indicate that a low-permeability veneer reduces the contribution of river water to a pumping well in a riparian aquifer to various degrees, depending on simulated hydraulic gradients, hydrogeological properties, and pumping conditions. Seepage of river water is reduced by 5-10% when a 2-cm thick, low-permeability veneer is present on the bed surface. Increasing thickness of the low-permeability layer to 0??1 m has little effect on distribution of seepage or percentage contribution from the river to the pumping well. A three-orders-of-magnitude reduction in hydraulic conductivity of the veneer is required to reduce seepage from the river to the extent typically associated with clogging at RBF sites. This degree of reduction is much larger than field-measured values that were on the order of a factor of 20-25. Over 90% of seepage occurs within 12 m of the shoreline closest to the pumping well for most simulations. Virtually no seepage occurs through the thalweg near the shoreline opposite the pumping well, although no low-permeability sediment was simulated for the thalweg. These results are relevant to natural settings that favour formation of a substantial, low-permeability sediment veneer, as well as central-pivot irrigation systems, and municipal water supplies where river seepage is induced via pumping wells. Published in 2011 by John Wiley & Sons, Ltd.

  7. Dental Implantology in U.S. Dental Schools.

    ERIC Educational Resources Information Center

    Bavitz, J. Bruce

    1990-01-01

    The results of a survey of 44 dental schools corroborate the belief that dental implantology is gaining widespread acceptance in U.S. dental schools. Currently, predoctoral students have limited clinical participation. Most programs have taken the position that clinical techniques are best taught within the existing specialties at a graduate…

  8. Bulimia and Anorexia Nervosa in Dental and Dental Hygiene Curricula.

    ERIC Educational Resources Information Center

    Gross, Karen B. W.; And Others

    1990-01-01

    Dentists and dental hygienists are in a unique position to identify an eating disorder patient from observed oral manifestations and to refer the patient for psychological therapy. The inclusion of information on general and oral complications of bulimia and anorexia nervosa in dental and dental hygiene curriculum was examined. (MLW)

  9. Dental practice network of U.S. dental schools.

    PubMed

    Fisher, Monica A; Beeson, Dennis C; Hans, Mark G

    2009-12-01

    As dental schools incorporate training in evidence-based dentistry (EBD) into their curricula, students must learn how to critically evaluate systematic reviews and meta-analyses. It is important that dental education in the United States support the American Dental Association's position statement on EBD, which defines "best evidence" as data obtained from all study designs. Given that much evidence is missing when EBD is derived from Cochrane Systematic Reviews' randomized clinical trials, we propose the creation of a dental practice network of U.S. dental schools. We developed an electronic clinical dentistry research database for EBD using Epi-Info (available at www.cdc.gov/epiinfo/downloads.htm). As a free, public use software, Epi-Info provides the foundation for the development of clinical research databases that can increase the research capacity through multisite studies designed to generate outcomes data on the effectiveness of dental treatment. The creation of a dental practice network of dental schools with their large number of patients would expand the research capacity for EBD practice and advance the EBD science regarding the effectiveness of dental treatment. The next step is to link clinical dental researchers/educators at multiple dental schools through a collaborative clinical research network, so that the findings can be applied to the EBD component of problem-based learning curricula of dental education. PMID:20007494

  10. Dental Health and Orthodontic Problems

    MedlinePlus

    ... Text Size Email Print Share Dental Health and Orthodontic Problems Page Content Article Body Dental Health Twin ... color can be tinted to match the teeth. Orthodontic Problems Crooked teeth, overbites and underbites are best ...