ABSTRACT
PURPOSE: To evaluate the effect of light-curing on the immediate and delayed micro-shear bond strength (microSBS) between yttria-tetragonal zirconia polycrystal (Y-TZP) ceramics and RelyX Ultimate when using Single Bond Universal (SBU). MATERIALS AND METHODS: Y-TZP ceramic specimens were ground with #600-grit SiC paper. SBU was applied and RelyX Ultimate was mixed and placed on the Y-TZP surface. The specimens were divided into three groups depending on whether light curing was done after adhesive (SBU) and resin cement application: uncured after adhesive and uncured after resin cement application (UU); uncured after adhesive, but light cured after resin cement (UC); and light cured after adhesive and light cured resin cement (CC). The three groups were further divided depending on the timing of microSBS testing: immediate at 24 hours (UUI, UCI, CCI) and delayed at 4 weeks (UUD, UCD, CCD). microSBS was statistically analyzed using one-way ANOVA and Student-Newman-Keuls multiple comparison test (P0.05). At 4 weeks, microSBS of UUD group (24.43+/-2.88 MPa) had significantly increased over time compared to UUI group (P<0.05). The SEM results showed mixed failure in UCI and CCI group, while UUI group showed adhesive failure. CONCLUSION: Light-curing of universal adhesive before or after application of RelyX Ultimate resin cement significantly improved the immediate microSBS of resin cement to air-abrasion treated Y-TZP surface. After 4 weeks, the delayed microSBS of the non-light curing group significantly improved to the level of light-cured groups.
Subject(s)
Adhesives , Ceramics , Resin CementsABSTRACT
Purpose: To analyze the stress distribution on a cantilever-fixed partial denture after simulation of maximum mastication loads in order to optimize its design. Methods: A cantilever-fixed partial denture framework was designed in the CAD-CAM system Everest®Kavo v2.0 using two materials, titanium and zirconium, with connectors of 5.28 mm² and 9.05 mm², respectively. A finite element model was built for stress analysis using simulations of mastication load. Results: For zirconia, only the molar cantilever with the smaller connector area and a 0.5-mm fillet exceeded the considered threshold resistance value of 575 MPa. All the other designs yielded resistances below this value. For titanium, only cantilevers with 9.05 mm² connector area and fillets of 1 or 1.4 mm presented stress values inferior to titanium yield strengh. Conclusion: Within the limitations of this study, it can be concluded that titanium cantilever-fixed partial denture frameworks with a 5.28 mm² connector area cannot support maximum mastication loads; frameworks of this material require larger connectors with fillets introduced in the gingival embrasure. Zirconia, however, supports maximum bite forces in most situations with both molar and premolar design cantilevers. Precaution should be taken when dealing with smaller connectors of 5.28 mm².
Objetivo: Analisar a distribuição de tensões em próteses parciais fixas em cantilever após aplicação de cargas simuladoras da mastigação, de forma a otimizar o seu desenho. Metodologia: Obteve-se a infra-estrutura de uma prótese parcial fixa em cantilever no sistema CAD-CAM Everest®Kavo v2.0, considerando dois materiais: titânio e zircônia, com conectores de 5,28 mm² e 9,05 mm², respectivamente. Gerou-se um modelo de elementos finitos, onde foram efetuadas análises de tensões com cargas simuladoras da mastigação. Resultados: Para zircônia, apenas o cantilever molar com área de conector mais reduzida, e concordância de 0,5 mm, excedeu o valor de resistência 575 MPa. Para o titânio, apenas o cantilever de 9,05 mm², com concordâncias de 1 e 1,4 mm, apresentou valores inferiores à tensão do titânio. Conclusão: Dentro das limitações deste estudo pode-se concluir que as infra-estruturas de titânio em cantilever não suportam cargas mastigatórias máximas com uma área de conector de 5,28 mm² e requerem conectores de áreas superiores, com concordâncias introduzidas na embrasura gengival. A zircônia geralmente suporta forças mastigatórias máximas com cantilever molar ou pré-molar. Deve-se ter precaução quando a área dos conectores é reduzida para 5,28 mm².
Subject(s)
Denture, Partial, Fixed , Titanium , Zirconium , Tensile StrengthABSTRACT
Purpose: To present a case report of a patient with amelogenesis imperfecta rehabilitated with 26 CAD-CAM all-ceramic fully sintered zirconia crowns.Case description: A male subject, 28 year-old, sought dental treatment presenting a clinical condition compatible with amelogenesis imperfecta. All teeth had yellow, brown, and white areas of weak enamel. Composite restorations were present on teeth 14, 16, 24, 25, 26, 27, and 46; dental caries were shown on teeth 36, 37, and 47. Hipersensitivity was reported. The treatment included fully sintered zirconia crowns for all teeth, using a CAD-CAM system. No problems of marginal adaptation of the crowns were detected, and the final results were satisfactory for both the patient and the clinician. Conclusion: The clinical rehabilitation of an amelogenesis imperfecta case is a challenge, and a multidisciplinary approach is required. Zirconia all-ceramics crowns are an excellent option to restore dental aesthetics as the opaque zirconia coping can mask dischromic abutments, and the crowns have biocompatibility and improved physical properties.
Objetivo: Apresentar o caso clínico de um paciente com amelogenesis imperfecta, que foi reabilitado com 26 coroas CAD-CAM de zircônia totalmente sinterizada. Descrição do caso: Um sujeito do sexo masculino, 28 anos, procurou tratamento odontológico apresentando uma condição clínica compatível com amelogenesis imperfecta. Todos os dentes tinham áreas amarelas, marrons e brancas de esmalte enfraquecido. Havia restaurações de resina composta nos dentes 14, 16, 24, 25, 26, 27 e 46; cárie dentária estava presente nos dentes 36, 37 e 47. Relatou-se hipersensibilidade dentária. O tratamento incluiu coroas de zircônia totalmente sinterizada para todos os dentes, usando um sistema CAD-CAM. Nenhum problema de adaptação marginal das coroas foi detectado e os resultados finais foram satisfatórios para ambos o paciente e o clínico. Conclusão: A reabilitação clínica de amelogenesis imperfecta é um desafio e a abordagem multidisciplinar deve ser mandatória. As coroas de zircônia são uma excelente opção para a reabilitação de pacientes com esta anomalia, pois o opaco dos copings de zircônia pode mascarar as diferentes cores dos pilares e o resultado final é esteticamente aceitável, com biocompatibilidade e propriedades físicas superiores.