Progress on the application of porcelain veneers in the restoration of dental fluorosis and its influencing factors / 中华地方病学杂志

Due to the cloud-like appearance of the dental surface of dental fluorosis, serious tooth defect may occur, thus affecting the overall beauty of the face. The clinical effect of dental fluorosis is not better than that of normal teeth in the application of repair, which brings some difficulties to the clinicians. The application of porcelain veneers in the restoration of dental fluorosis has been widely concerned by clinicians and researchers due to its advantages of high aesthetics, small amount of tooth tissue abrasion, and good biocompatibility. Therefore, this article comprehensively discusses the application effect and influencing factors of porcelain veneers in the restoration of dental fluorosis, in order to provide some reference for clinical application.

Comparison of porcelain veneer fracture in implant-supported fixed full-arch prostheses with a framework of either titanium, cobalt-chromium, or zirconia: An in vitro study.

OBJECTIVES: The aim of this study was to compare porcelain veneer strength on screw-retained implant-supported fixed full-arch prostheses with a framework of either milled titanium (Ti), cobalt-chromium (CoCr), and yttria-stabilized zirconia (Y-TZP) in an in vitro loading model. MATERIALS AND METHODS: Fifteen screw-retained maxillary implant-supported full-arch prostheses (FDP), five each of Ti, CoCr, and Y-TZP frameworks with porcelain veneers were included. All FDPs were subjected to thermocycling before loading until fracture of the veneer. The load was applied at the distal fossa of the occlusal area of the pontic replacing 24. Fracture loads were analyzed, and the fracture quality was assessed. Statistical analysis on the fracture load was performed using Kruskal-Wallis test. The statistical significance was set at p < .05. RESULTS: There was no statistical significance found between the groups regarding fracture load. The highest and lowest load was seen within the CoCr FDP, varying between 340 and 1484 N. Different types of fracture appearances were seen. The Y-TZP FDPs had a higher number of fractures locally in the loaded area while CoCr and Ti more often showed cracks in the anterior region, at a distance from the loaded area. CONCLUSIONS: Within the limitations of this study, the conclusion was that framework material may affect the fracture behavior of maxillary full-arch bridges; however, there were no differences in veneer fracture strength when frameworks of Ti, CoCr, or Y-TZP were compared.

Effect of core and veneer porcelain thickness and resin cement on opalescence property of glass-ceramic veneers.

OBJECTIVES: This study aimed to analyze the effect of core and veneer porcelain thickness and resin cement on the opalescence property (OP) of glass-ceramic veneers, which were used to restore discolored teeth. METHODS: IPS e.max CAD LT A3 ceramic specimens were fabricated by computer aided design and computer aided manufacturing (CAD/CAM). The thickness values of core porcelain groups were 0.25 and 0.50 mm, and those of the core/veneer porcelain groups were 0.25 mm core/0.25 mm dentin, 0.50 mm core/0.25 mm dentin, 0.50 mm core/0.50 mm dentin, and 0.50 mm core/0.25 mm dentin/0.25 mm incisal. To simulate the clinical bonding procedure of porcelain veneer, resin cement Variolink N Bleach XL was coated at the bottom of CAD/CAM porcelain veneer specimens to make composite specimens of CAD/CAM porcelain veneer and resin cement. The L*a*b* values of specimens in the reflection and transmission pattern were measured by a spectrophotometer. Then, the OP was calculated. RESULTS: The OP values of 0.25 and 0.50 mm core porcelain groups, and 0.25 mm core/0.25 mm dentin, 0.50 mm core/0.25 mm dentin, 0.50 mm core/0.50 mm dentin, and 0.50 mm core/0.25 mm dentin/0.25 mm incisal core/veneer porcelain groups were 6.10±0.50, 7.00±0.24, 6.40±0.24, 7.08±0.28, 7.16±0.21, and 7.86±0.11 respectively. With increasing thickness of core porcelain, the OP values increased significantly (P<0.05). When 0.25 mm-thick dentin porcelain was added, no significant difference was found in the OP values of specimens with the same core porcelain thickness (P>0.05). For the 0.50 mm core porcelain group, no significant difference was found between 0.25 and 0.50 mm-thick dentin porcelain groups (P>0.05), but the OP values increased significantly after increasing the 0.25 mm incisal porcelain (P<0.05). The OP values of 0.25 mm core/0.25 mm dentin, 0.50 mm core/0.25 mm dentin, 0.50 mm core/0.50 mm dentin, and 0.50 mm core/0.25 mm dentin/0.25 mm incisal CAD/CAM porcelain veneer-resin cement composite specimens were 6.29±0.31, 7.56±0.36, 7.67±0.30, and 8.65±0.53. The OP values increased with increasing thickness of the porcelain layer (P<0.05), but no statistically signi-ficant difference was found between the groups of 0.50 mm core/0.25 mm dentin and 0.50 mm core/0.50 mm dentin (P=0.733). The influence of porcelain layer thickness and resin cement on the OP value was statistically different (P<0.05), and no interaction was found between the total thickness and the presence of resin cement (P>0.05). CONCLUSIONS: When using glass-ceramic veneers for discolored teeth, the following are recommended to improve the OP and obtain a natural and realistic effect: adopt the design of direct sintering incisal porcelain with core porcelain; appropriately increase the thickness of core porcelain; and select resin cement with opaque effect.

Digital partition bonding for porcelain veneers guided by sequence 3D printing templates.

Obtaining optimal enamel bonding is a common recommendation to ensure the retention, edge closure, and clinical service life of porcelain veneers. Bonding surface is determined after tooth preparation. More or less dentin exposure often occurs due to the uneven thickness of the enamel. Identifying the enamel or dentin on the bonding surface and adopting the "selective etching" technique are useful to obtain the maximal bonding strength. Naked eye recognition in "selective etching" has uncertain results and is experience-based, whereas the proposed technique controls the preparation depth through the first target restoration space template to obtain the accurate enamel and dentin subarea. It is mapped to the second bonding template, depending on the treatment carried out on the enamel and dentin surface, to accurately predict the adhesion of porcelain veneers.

Effect of ceramic materials on the optical properties of porcelain veneers for tetracycline-stained teeth.

OBJECTIVES: To analyze the chromatic properties and translucency of porcelain veneers made from different ceramic materials against the background of tetracycline-stained teeth. METHODS: Porcelain specimens (A1, A3, B2, B4) measuring 0.50 mm in thickness were prepared by heat-press casting and layering. The L*, a*, and b* values of the specimens against simulated tetracycline tooth and black-and-white backgrounds were measured by a spectrophotometer, and color differences ΔE001 between specimens on simulated tetracycline backgrounds and the backgrounds themselves and ΔE002 between specimens on simulated tetracycline backgrounds and the white background were calculated. The translucent parameter (TP) was also evaluated. RESULTS: The ΔE001 of feldspathic specimens (IPS d.SIGN) with the opaque layer was significantly greater than that of glass ceramic specimens (IPS e.max Press LT), and the ΔE001 of group B4 was consistently greater than those of the other color groups (P<0.05). The ΔE002 values of all feldspathic specimens with the opaque layer were less than 1.25, and the ΔE002 values of the glass ceramic specimens were greater than 2.23. However, no significant difference was observed among the different color groups (P>0.05). The TP values of feldspathic specimens with the opaque layer were significantly lower than those of glass ceramic specimens(P<0.05), but no significant difference was observed among different color groups (P>0.05). CONCLUSIONS: When changing the color of tetracycline-stained teeth, 0.50 mm-thick IPS d.SIGN feldspathic veneers with an opaque layer provide better chromatic properties than IPS e.max Press LT glass ceramic veneers. However, the translucency of feldspathic veneers is generally poorer than that of glass ceramic veneers.

In-vitro efficacy of two spectrophotometer-based shade matching systems for color matching of ceramics after artificial accelerated aging / Eficácia in vitro de dois espectrofotômetros baseados em escalas de cor para avaliação de cor de cerâmicas após envelhecimento artificial acelerado

Objective: The objective of the present in-vitro study was to verify the efficacy of two spectrophotometer-based shade matching systems for color matching of ceramics after artificial accelerated aging (AAA). Material and Methods: The ceramics used were porcelain laminated veneers. Seventy standard-shaped discs (thickness x diameter: 0.5 mm x 10 mm) of B1 shades were used. Based upon the type of resin cement used, the specimens were divided into seven groups (10/group). The following light-cured cements were used: RelyX-Veneer (L-RV), Variolink-Veneer (L-VV), and Variolink-Esthetic (L-VE). The dual-cured cements were: RelyX Ultimate (D-RU), RelyX-Unicem (D-RC), and Variolink-Esthetics DC (D-VE). The control group consisted of ceramic only. All specimens were thermocycled in water for 3,500 cycles between 5 oC -55 oC, with dwell times of 30 s in each bath and a transfer time of 10 s between baths. All specimens were thermocycled in water for 3,500 cycles between 5 oC and 55 oC, and color measurement was done using the VITA Easyshade and ColorEye spectrophotometers. Baseline color reading was performed 24-hours after cementation. Differences in color (DE) of EasyShade and ColorEye before and after AAA were determined and compared statistically. Group comparisons were done using the paired t-tests. Level of significance was set at P< 0.05. Results: The mean differences in color (ΔE) values obtained from EasyShade spectrophotometer for light- and dual-cured cements, were 0.843±0.89 (L-RV ), 4.11±0.69 (L-VV) and 0.833±0.47 (L-VE); and 2.22±0.64 (D-RU), 3.37±0.83 (D-RC) and 0.38±0.92 (D-VE), respectively. The mean differences in color (ΔE) values obtained from ColorEye spectrophotometer for light- and dual-cured cements, were 0.68±0.86 (L-RV ), 4.55±0.83 (L-VV) and 2.68±0.26 (L-VE); and 2.06±0.84 (D-RU), 1.8±1.08 (D-RC) and 0.96±0.71 (D-VE), respectively. There was no significant difference in the mean DE values among the groups. Conclusion: The VITA Easyshade and ColorEye shade matching systems are comparable in terms of their efficacy for color matching of cerammics after AAA.(AU)

Objetivos: O objetivo do presente estudo in vitro foi verificar a eficácia de dois espectrofotômetros baseados em escalas de cor para avaliação de cor de cerâmicas após envelhecimento artificial acelerado (EAA). Material e Métodos: As cerâmicas utilizadas foram laminados cerâmicos. Foram usados setenta discos de formato padrão (0,5mm de espessura x 10 mm de diâmetro) de tonalidades B1. Com base no tipo de cimento resinoso utilizado, os corpos-de-prova foram divididos em sete grupos (10 / grupo). Foram utilizados os seguintes cimentos fotopolimerizáveis: RelyX-Veneer (L-RV), Variolink-Veneer (L-VV) e Variolink-Esthetic (L-VE). Os cimentos de cura dual foram: RelyX Ultimate (D-RU), RelyX-Unicem (D-RC) e Variolink-Esthetics DC (D-VE). O grupo controle consistia apenas de cerâmica. Todos os corpos-de-prova foram termociclados em água por 3.500 ciclos entre 5oC-55oC, com tempos de permanência de 30s em cada banho e um tempo de transferência de 10s entre os banhos. A medição da cor foi feita usando os espectrofotômetros VITA Easyshade e ColorEye. A leitura da cor inicial foi realizada 24 horas após a cimentação. As diferenças na cor (ΔE) do EasyShade e ColorEye antes e depois do EAA foram determinadas e comparadas estatisticamente. As comparações dos grupos foram feitas usando o teste t pareados. O nível de significância foi estabelecido em p <0,05. Resultados: os valores médios de diferenças na cor (ΔE) obtidos no espectrofotômetro EasyShade para cimentos fotopolimerizáveis e duais foram de 0,843 ± 0,89 (L-RV), 4,11 ± 0,69 (L-VV) e 0,833 ± 0,47 (L-VE ); e 2,22 ± 0,64 (D-RU), 3,37 ± 0,83 (D-RC) e 0,38 ± 0,92 (D-VE), respectivamente. os valores médios de diferenças na cor (ΔE) obtidos no espectrofotômetro ColorEye para cimentos fotopolimerizáveis e duais foram de 0,68 ± 0,86 (L-RV), 4,55 ± 0,83 (L-VV) e 2,68 ± 0,26 (L-VE); e 2,06 ± 0,84 (D-RU), 1,8 ± 1,08 (D-RC) e 0,96 ± 0,71 (D-VE), respectivamente. Não houve diferença significativa nos valores médios de ΔE entre os grupos. Conclusão: Os sistemas de combinação de cores VITA Easyshade e ColorEye são comparáveis em termos de eficácia para avaliação de cores de cerâmicas após EAA. (AU)

Effect of ceramic materials on the optical properties of porcelain veneers for tetracycline-stained teeth / 华西口腔医学杂志

OBJECTIVES@#To analyze the chromatic properties and translucency of porcelain veneers made from different ceramic materials against the background of tetracycline-stained teeth.@*METHODS@#Porcelain specimens (A1, A3, B2, B4) measuring 0.50 mm in thickness were prepared by heat-press casting and layering. The L*, a*, and b* values of the specimens against simulated tetracycline tooth and black-and-white backgrounds were measured by a spectrophotometer, and color differences ΔE@*RESULTS@#The ΔE@*CONCLUSIONS@#When changing the color of tetracycline-stained teeth, 0.50 mm-thick IPS d.SIGN feldspathic veneers with an opaque layer provide better chromatic properties than IPS e.max Press LT glass ceramic veneers. However, the translucency of feldspathic veneers is generally poorer than that of glass ceramic veneers.

Monolithic CAD/CAM laminate veneers: Reliability and failure modes.

OBJECTIVES: to evaluate the probability of survival and failure modes of lithium-disilicate, feldspathic-ceramic, and resin-nanoceramic anterior veneers cemented on dentin analog substrates after sliding-contact step-stress accelerated life testing (SSALT). METHODS: A virtual incisor tooth preparation was produced with a reduction of 1.5mm at the incisal edge and of 0.7mm buccally. A .STL file of the preparation was generated and CAD/CAM based G10 dentin-analog material was used for testing. Laminate veneers were milled in three different materials: lithium-disilicate (LDS, E.max CAD), resin-nanoceramic (RN, Lava Ultimate), and feldspathic-ceramic (FELDS, Vita Blocks). SSALT was employed where a spherical indenter contacted the veneer, slided along its interface with G10 to lift off and start a new cycle at 2Hz in water. Qualitative fractography was performed. The probability of survival (90% confidence-bounds) was calculated for several load/cycle missions. RESULTS: The probability of survival for a mission of 50,000 cycles decreased from 50 up to 150N equally for all groups and were not different between them. At 200N, the probability of survival was significantly lower for FELDS (10%) compared to RN veneers (41%), whereas LDS presented intermediate values (22%). The characteristic strength of RN (247N) was significantly higher than LDS (149N), and FELDS (151N). In FELDS and LDS, hackles, wake hackles and twist hackles indicated the direction of crack propagation. In RN, hackles were observed. CONCLUSIONS: Differences in probability of survival were observed only at 180 and 200N between groups. Failure modes were similar with veneer fracture down to the tooth-analog substrate.

Evaluation of Stress Distribution in Tooth-Supported Fixed Dental Prostheses Made of Translucent Zirconia with Variations in Framework Designs: A Three-Dimensional Finite Element Analysis.

PURPOSE: To evaluate the influence of the framework designs on the stress distribution within tooth-supported partially veneered fixed dental prostheses (FDPs) made of translucent zirconia under simulated loads using a three-dimensional finite element analysis (3D-FEA). MATERIAL AND METHODS: For a linear 3D-FEA, simplified 3D solid models of prepared abutment teeth (first premolar and first molar) with different 3-unit FDPs were created. The models with different FDP designs-monolithic zirconia (control); semi-monolithic zirconia with 0.3 mm veneer thickness (SM0.3); semi-monolithic zirconia with 0.5 mm veneer thickness (SM0.5); semi-monolithic zirconia with 0.5 mm veneer thickness supported with cap design (SMC), and semi-monolithic zirconia with 0.5 mm veneer thickness supported with wave design (SMW)-were analyzed using 3D-FEA. The elastic properties of the components (bone, dentine, cement, translucent zirconia, and veneering porcelain) were obtained from the published data for FEA. Simulated static loading forces (300 N) were applied at 10° oblique direction over six points in the occlusal surfaces of the FDPs. Maximum principal stress, shear stress, and safety factor were calculated and analyzed among the different models. RESULTS: Semi-monolithic with cap design showed the smallest maximum principal stress levels in the veneering porcelain compared to all other models (SM0.3, SM0.5, SMW). The SM0.3 had lower maximum principal stress levels in the veneering porcelain compared to SM0.5. Regarding stresses in the zirconia framework, all models had comparable results in maximum principal tensile stresses, except SMW had a lower value. Maximum principal stress levels were located in the veneer component of SM0.3, SM0.5, and SMW, whereas, such levels were observed in the cervical areas of the zirconia frameworks of SMC and control. The SM0.3 had the highest maximum shear stress levels at the zirconia-veneer interface, while SMW had the lowest shear values. The 3D-FEA models with different FDP designs showed different minimum safety factor levels. CONCLUSIONS: Framework and veneer designs play a significant role in the stress distribution of the partially veneered zirconia FDPs under loading. The FDPs with zirconia frameworks with cap design minimize the maximum principal tensile stress in the veneering porcelain. The FDPs with 0.3-mm-veneering porcelain show low maximum principal tensile stress in the veneering porcelain, but highest maximum shear stress at the zirconia-veneer interface. The FDPs with wave design of zirconia frameworks minimize the maximum shear stress considerably.

Effect of thermal and mechanical cycles on shear bond strength of zirconia core to porcelain veneer under different surface treatments.

Background. Due to the fragile nature of all-ceramic restorations, it is necessary to provide an appropriate (core) infrastructure to support the veneering porcelain. The veneer detachment and chipping are disadvantages of these restorations. Several techniques have been proposed to minimize these problems. This study evaluated the effect of thermal and mechanical cycles on the shear bond strength of zirconia core to porcelain veneer under different surface treatments. Methods. Sixty disk-like zirconium samples were randomly divided into three groups. The first group was polished and veneered with porcelain, without additional surface treatments. The two other groups were subjected to different surface treatments (modified aluminum oxide by silica and activator‒aluminum oxide and primer) and veneering with porcelain. Half of the samples in each group were subjected to 6000 thermal cycles and 20,000 masticatory cycles of 50 N to imitate the intraoral conditions; the other half were placed in distilled water at 37°C until the shear strength test. Each sample was then buried using PMMA in a mounting jig so that the gap between the core and the veneer could be placed upward. Then, they were exposed to shear stress using a universal testing machine at a rate of 1 mm/min until fracture. The maximum force leading to the fracture was recorded. Results. Comparison of the groups showed that the highest shear bond strength was related to the samples treated with aluminum oxide and primer, without applying thermal and masticatory cycles, which indicated no significant difference from the group treated with aluminum oxide and primer, with thermal and masticatory cycles. The lowest shear bond strengths were related to the polished samples without surface treatment by applying thermal and masticatory cycles (P=0.001), which indicated no significant difference from the untreated group without thermal and masticatory cycles. Conclusion. Based on the results, treatment with aluminum oxide and primer increased the shear bond strength of zirconia core to porcelain veneer. Thermocycling and masticatory cycles failed to reduce the shear bond strength in all the three groups significantly.

Clinical application of digital smile design in aesthetic restoration of porcelain veneer of anterior teeth and analysis on its repair effect / 吉林大学学报(医学版)

Objective: To analyze the postoperative satisfaction and repair effect of prosthesis of the patients who received digital smile design(DSD) combined with porcelain veneers in the anterior teeth, and to illustrate the their application in anterior teeth aesthetic restoration. Methods: A total of 91 anterior teeth of 32 patients whose clinical diagnosis conformed to the indications of porcelain veneers and aesthetic restoration because of tetracycline pigmentation teeth, dental fluorosis, color stained teeth, enamel defects and anterior teeth space were selected. DSD software was used to design the preoperative aesthetic analysis of the teeth morphology and to show the virtual effect of restoration. The preparation of tooth under the guidance of the design results was finished. The IPS e-max porcelain veneers were prepared after the conventional impression preparation. At last, the permanent restorations were manufactured and bonded to teeth. After the adhesive program was completed, the satisfaction of the patients in the shape of restorations, the degree of coordination with the adjacent teeth, color, pronunciation, smile effect and doctor-patient communication effect were evaluated by the questionnaires. The patients were required to regularly return after one month, three months, six months and twelve months, and observe the clinical effects of restoration was observed referring to the modified American Public Health Service (USPHS) standard. Results: The patients' satisfaction rates of each evaluation content were all over 90%. Among them, the satisfaction rates of the smile effect and the doctor patient communication were as high as 100%. The clinical performances of the rehabilitations in each period were as follows: One month after treatment, there were four teeth occurred mild gingivitis and three teeth appeared the postoperative sensitivity symptoms; three months after treatment, there were one tooth showed a minor fracture in the restoration without affecting the appearance and function and three teeth had mildly congestive gums reaction, at the same time one tooth showed slight discoloration of the restoration; six months after treatment, one tooth showed ceramics fracture of restoration and four teeth developed mild gingivitis; twelve months after treatment, two teeth showed ceramics fracture, the edge of three restorations had slightly crack and one tooth appeared gingivitis. The periodontal conditions of the patients with gingival inflammation after treatment were improved significantly after receiving the correct oral hygiene guidance. The above defects didn't affect the aesthetics effect and the functions of restorations, and the restorations could be used normally after intraoral adjustments. Both the doctors and the patients were satisfied with the repair effects of the restorations. Conclusion: The combination of DSD and porcelain veneer in repairing anterior aesthetic teeth is good treatment plan that can achieve high patient satisfaction and ideal clinical effect.

Effect of dentin exposure on the shear bond strength of cast porcelain veneers / 口腔疾病防治

Objective@#To explore the best indication for veneers and to improve the repair success rate by investigating the effects of different types of dentin exposure on the shear bond strength of cast porcelain veneers with two new veneer bonding systems.@*Methods@#Bonding interfaces with 0%, 25%, 50%, 75% and 100% dentin exposure were designed and fabricated. The bonding interfaces were divided into groups A, B, C, D and E. Sixty 4-mm x 4-mm x 2-mm (length x width x thickness) ceramic specimens were bonded by using two bonding systems, The VN-A, VN-B, VN-C, VN-D and VN-E groups were bonded with Variolink bonding system, and the PF-A, PF-B, PF-C, PF-D and PF-E were bonded with Panavia F bonding system (six specimens per group). The bonded specimens were stored in a distilled water bath at (37 + 1)℃ for 24 hours. The fracture load was tested by a universal testing machine, and the fracture type was observed by scanning electron microscopy.@*Results @#The VN-A (25.14 ± 3.40 MPa), VN-B (22.54 ± 4.48 MPa), VN-C (19.59 ± 2.21 MPa), PF-A (20.61 ± 2.42 MPa), PF-B (18.08 ± 4.11 MPa), PF-C (17.06 ± 2.29 MPa) groups’ shear bond strengths were above 17 MPa. The VN-A group had the highest shear bond strength value. There was no statistically significant difference in bond strength between the VN-A group and the VN-B and VN-C groups (P > 0.05) or the PF-A and PF-B groups (P > 0.05); however, the differences between VN-A and the VN-D and VN-E groups (P < 0.05) and between PF-A and the PF-C and PF-D and PF-E groups (P < 0.05) were statistically significant. The differences between the VN-A group and PF-A group (P < 0.05) were statistically significant. The fracture modes of the VN-A, PF-A, VN-B, PF-B, and VN-C groups mainly included resin cement cohesive failure and mixed failure; the VN-D, VN-E, PF-C, PF-D and PF-E groups were dominated by interface failure and mixed failure.@*Conclusion@#When the dentin exposure is greater than 50%, the shear bond strength value of the veneer was significantly affected. To obtain a better clinical effect, the dentin exposure rate should be less than 25%.

Effect of different semimonolithic designs on fracture resistance and fracture mode of translucent and high-translucent zirconia crowns.

PURPOSE: The aim of this study was to describe different designs of semimonolithic crowns made of translucent and high-translucent zirconia materials and to evaluate the effect on fracture resistance and fracture mode. METHODS: One hundred crowns with different designs were produced and divided into five groups (n=20): monolithic (M), partially veneered monolithic (semimonolithic) with 0.3 mm buccal veneer (SM0.3), semimonolithic with 0.5 mm buccal veneer (SM0.5), semimonolithic with 0.5 mm buccal veneer supported by wave design (SMW), and semimonolithic with 0.5 mm buccal veneer supported by occlusal cap design (SMC). Each group was divided into two subgroups (n=10) according to the materials used, translucent and high-translucent zirconia. All crowns underwent artificial aging before loading until fracture. Fracture mode analysis was performed. Fracture loads and fracture modes were analyzed using two-way ANOVA and Fisher's exact probability tests (P≤0.05). RESULTS: SM0.3 design showed highest fracture loads with no significant difference compared to M and SMW designs (P>0.05). SM0.5 design showed lower fracture loads compared to SMW and SWC designs. Crowns made of translucent zirconia showed higher fracture loads compared to those made of high-translucent zirconia. M, SM0.3, and all but one of the SMC crowns showed complete fractures with significant differences in fracture mode compared to SMW and SM0.5 crowns with cohesive veneer fractures (P≤0.05). CONCLUSION: Translucent and high-translucent zirconia crowns might be used in combination with 0.3 mm microcoating porcelain layer with semimonolithic design to enhance the esthetic properties of restorations without significantly decreasing fracture resistance of the crowns. If 0.5 mm porcelain layer is needed for a semimonolithic crown, wave design or cap design might be used to increase fracture resistance. In both cases, fracture resistance gained is likely to be clinically sufficient as the registered fracture loads were high in relation to expected loads under clinical use.

Fracture strength of veneered translucent zirconium dioxide crowns with different porcelain thicknesses.

Objective: To evaluate fracture strength of veneered translucent zirconium dioxide crowns designed with different porcelain layer thicknesses. Materials and Methods: Sixty crowns, divided into six groups of 10, were used in this study. Groups were divided according to different thicknesses of porcelain veneer on translucent zirconium dioxide cores of equal thickness (0.5 mm). Porcelain thicknesses were 2.5, 2.0, 1.0, 0.8, 0.5 and 0.3 mm. Crowns were artificially aged before loaded to fracture. Determination of fracture mode was performed using light microscope. Results: Group 1.0 mm showed significantly (p ≤ .05) highest fracture loads (mean 1540 N) in comparison with groups 2.5, 2.0 and 0.3 mm (mean 851, 910 and 1202 N). There was no significant difference (p>.05) in fracture loads among groups 1.0, 0.8 and 0.5 mm (mean 1540, 1313 and 1286 N). There were significantly (p ≤ .05) more complete fractures in group 0.3 mm compared to all other groups which presented mainly cohesive fractures. Conclusions: Translucent zirconium dioxide crowns can be veneered with minimal thickness layer of 0.5 mm porcelain without showing significantly reduced fracture strength compared to traditionally veneered (1.0-2.0 mm) crowns. Fracture strength of micro-veneered crowns with a layer of porcelain (0.3 mm) is lower than that of traditionally veneered crowns but still within range of what may be considered clinically sufficient. Porcelain layers of 2.0 mm or thicker should be used where expected loads are low only.

Effect of newly Developed Resin Cements and Thermocycling on the Strength of Porcelain Laminate Veneers.

AIM: The aim of this study was to determine the effect of different luting cements and accelerated artificial aging (AAA) in the fracture resistance of porcelain laminate veneers (PLVs). MATERIALS AND METHODS: A total of 80 disc-shaped specimens were prepared using computer-aided design/computer-aided milling technology from lithium disilicate glass-ceramic blocks. Specimens (0.5 mm thick, 10 mm diameter) were divided into eight groups of 10 specimens per group. The control groups consisted of specimens without cement and not subjected to AAA (CN group) and specimens prepared without cement but subjected to AAA (CW group). The experimental groups were subjected to AAA and cemented with Variolink Veneer, Variolink Esthetic LC, Variolink Esthetic DC, RelyX Unicem, RelyX Veneer, or RelyX Ultimate. Specimens were individually tested for biaxial flexure on a universal testing machine. One-way analysis of variance and the Tukey's post hoc test were used to compare the groups' significance statistically (α = 0.05). RESULTS: The loads to fracture (LTF) values in the CN group were higher than those in the CW and experimental groups. The lowest LTF value was in the CW group (31.5 ± 9.5 N) and the highest LTF value in the CN group (56.7 ± 10.6 N). Tukey's post hoc test demonstrated a statistically significant (p < 0.01) difference between the CN group and the other groups. CONCLUSION: Artificial aging had a significant effect on the LTF value of the tested specimens compared with the resin cements used. Cohesive failure within the PLVs was the most common mode of failure. CLINICAL SIGNIFICANCE: Fatigue strength of dental ceramics and moisture was shown to affect the mechanical properties of all-ceramic restorations. All-ceramic material is extremely sensitive to humidity and thermocycling.

Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create 3D crown models and evaluated using FEA. The zirconia/composite crowns subjected to static occlusal load showed comparable results to the zirconia/porcelain crowns. Zirconia/composite crowns showed higher stress on the zirconia substructure at 63.6 and 50.9 MPa on the zirconia substructure veneered with porcelain. In conclusion, zirconia/composite crowns withstood high occlusal loads similar to zirconia/porcelain crowns with no significant difference. However, the zirconia/composite crowns showed higher stress values than the zirconia/porcelain crowns at the zirconia substructure.

Influence of Different Framework Designs on the Fracture Properties of Ceria-Stabilized Tetragonal Zirconia/Alumina-Based All-Ceramic Crowns.

The aim of this study was to evaluate the fracture load and failure mode of all-ceramic crowns with different ceria-stabilized tetragonal zirconia/alumina nanocomposite (Ce-TZP/A) framework designs. Four frameworks (anatomical shape: AS, with a buccal or lingual supporting structure: BS and LS, or buccal and lingual supporting structures: BLS) were fabricated. All frameworks were veneered with porcelain to fabricate all-ceramic crowns followed by cementation to tooth analogs. The fracture load of each crown either without or with pre-loading (1.2 million cycles, 49 N) was measured. The failure mode was classified into partial or complete fracture. Differences were tested for significance (p < 0.05) by a two-way Analysis of Variance (ANOVA), followed by Tukey's test and by Fisher's exact test, respectively. Without pre-loading, supporting structures did not influence the fracture load or failure mode. Partial fractures were the most common failure mode. Pre-loading promoted the severity of the failure mode, although the fracture load among the framework designs was not influenced. In the AS group, prefailures were observed during pre-loading, and complete fractures were significantly increased after pre-loading. In contrast, the failure mode of the BLS group remained unchanged, showing only partial fracture even after pre-loading. This Ce-TZP/A framework design, comprised of an anatomical shape with additional buccal and lingual structures, has the potential to reduce the chipping of the veneering porcelain.

Comparison of the clinical efficacy between two kinds of ceramic veneer restoration / 实用口腔医学杂志

Objective:To evaluate the clinical efficacy between preparation porcelain veneer(PPV)and no-preparation porcelain veneer(NPPV).Methods:44 patients with 97 PPVs and 23 patients with 57 NPPVs were followed up for 3 years.Mental tension, postoperative dentin sensitivity and satisfaction of the patients,survival rate of the veneers,sulcus bleeding index(SBI)of preopera-tive and postoperative 3 years were evaluated.A comparative analysis was taken to examine the clinical indicators of 2 groups accord-ing to the modified CDA /Ryge criteria.Results:Survival rates of PPVs and NPPVs were 96.91 % and 96.49%(P >0.05),satisfac-tion rates of the 2 group patients were 95.45% and 95.65%(P >0.05),respectively.Mental tension and the postoperative dentin sensitivity of patients in PPV group was higher than those in NPPV group.Preoperative and postoperative SBI were not statistically dif-ferent between the 2 groups(P >0.05).Marginal adaptation in PPV group was better than that in NPPV group.Color matching, Porcelain surface and Marginal stain were not statistically different between 2 groups.Conclusion:Preparation porcelain veneers and no-preparation porcelain veneers both are effective in clinical application.

Restoration of Fluorosis Stained Teeth: A Case Study.

Dental fluorosis manifests by too much ingestion of fluoride resulting in disturbances in enamel mineralization. The result is intrinsic discolorations in the maxillary and mandibular teeth with a poor esthetic appearance. In challenging cases, an esthetic result may be achieved only by a combination of techniques. This case report demonstrates a combination of modalities used to treat a patient presenting with atypical staining as a result of high-level exposure to ingested fluoride present in the drinking water as a child. Conservative treatment consisted of a combination of in-office bleaching to reduce the discoloration and porcelain veneers to create an esthetic result.

Restorations of anterior upper teeth with partial coverage porcelain veneers / 中华医学美学美容杂志

Objective To restore the incisal angle defect of anterior upper teeth with partial cov-erage porcelain veneer, and evaluate the clinical performance of the restoration. Methods A total of 12 patients were included, and 14 anterior upper teeth with small incisal angle defect were involved in this study, after tooth reduction of 2 mm wider than the defect of every teeth, 14 partial coverage IPS-Empress Ⅱ veneers were made and binded with Variolink Ⅱ adhesive system. During the observation period of 36-48 months after insertion, prosthodontic results were evaluated, using the CDA quality e-valuation system, and marginal integrity, anatomic form, surface and color of the veneers, and sec-ondary caries were examined. Results During the period of 36-48 observation, all of the 14 restora-tions were rated satisfactory. Conclusions With strict control of indications, the partial coverage porcelain veneer could function satisfactorily as an alternative restoration for small incisal defect of an-terior upper teeth.