Modified Technique of Porcelain Laminate Veneer in Premolars with Abfraction Lesions: Three-Dimensional Finite Element Analysis (FEA)

The incidence of non-carious cervical lesions (NCCLs) has increased as populations are aging, and teeth are increasingly retained for life. Several materials are available to treat these lesions. This study aimed to evaluate the stress distribution of maxillary premolars with NCCLs using three-dimensional (3D) finite element analysis (FEA) according to different restorative techniques. A 3D FEA mathematical model simulating a sound premolar was initially modeled and replicated in 6 more models simulating a tooth with abfraction: G.1 tooth with abfraction; G.2 tooth with abfraction + composite resin restoration; G.3 tooth with abfraction + glass-ionomer cement restoration; G.4 tooth with abfraction + resin composite restoration + porcelain laminate veneers; G.5 tooth with abfraction + glass-ionomer cement + porcelain laminate veneers; and G.6 modified porcelain laminate veneers filling the lesion. All materials and structures were considered linear, elastic, homogeneous and isotropic and the results were expressed as maximum principal stress. Lower stress concentration in dentin was calculated when the tooth was restored with composite resin and glass-ionomer cement. Regarding the veneer techniques, no difference was found to dentin stress among the groups, but the modified veneer concentrated less stress in the restoration than other the techniques. The control group had the highest concentration of stress in the lesion. All techniques decreased the stress concentration inside the NCCLs and the indirect veneer filling the lesion presented better biomechanical behavior than the veneer cemented above direct restorations.  Keywords: Finite Element Analysis. Dental Veneers. Ceramics. Bicuspid. Resumo A incidencia de lesoes cervicais nao-cariosas (LCNC) tem aumentado, uma vez que a populacao tem envelhecido com uma menor perda de elementos dentarios. Diferentes materiais estao disponiveis para tratar dessas lesoes. Este estudo objetivou avaliar a distribuicao de tensao de pre-molares superiores com LCNC por meio da analise tridimensional (3D) de elementos finitos (FEA) de acordo com diferentes tecnicas restauradoras. Um modelo matematico 3D FEA simulando um pre-molar integro foi modelado e replicado em mais 6 modelos simulando um dente com abfracao: G.1 dente com abfracao; G.2 dente com abfracao + resina composta; G.3 dente com abfracao + cimento de ionomero de vidro; G.4 dente com abfracao + resina composta + faceta; G.5 dente com abfracao + cimento de ionomero de vidro + faceta cerâmica e G.6 com faceta cerâmica modificada, preenchendo a lesao. Todos os materiais e estruturas foram considerados lineares, elasticos, homogeneos e isotropicos e os resultados foram expressos como maxima tensao principal. Menor concentracao de tensao na dentina foi calculada quando o dente foi restaurado com resina composta ou cimento de ionomero de vidro. Dentre os grupos com laminados, nao houve diferenca para a dentina, entretanto a faceta modificada apresentou menor concentracao de tensao na restauracao. O grupo controle apresentou a maior concentracao de tensao na lesao. Todas as tecnicas restauradoras diminuiram a concentracao de tensao no interior das LCNCs e dentre as tecnicas com laminados a faceta modificada apresentou o melhor comportamento biomecânico. Palavras-chave: Analise de Elementos Finitos. Facetas Dentarias. Cerâmica. Dente Pre-Molar.