Stress distribution on the tooth varying the ceramics restorations

The ceramic restorations have been successfully used supported by biomimetic concept. However, the data about the stress distribution at the tooth-restoration interface varying the ceramics systems are not conclusive. Objective: To evaluate the stress distribution on the tooth-restoration interface of the laminate veneer or full crown using two ceramics systems (IPS Empress and Procera) under different loadings. Methods: Six 2-dimensional finite element models of a maxillary central incisor were built varying the ceramics systems: laminate veneer (IPS Empress, IPS Empress Esthetic and Procera) and total crown (IPS Empress 2 and Procera AllCeram); and the loading condition (L): L1 – 50N in the lingual face, in 45⁰ with the tooth long axis, and L2 – 50N perpendicular to the incisal edge. The von Mises equivalent stress criteria (s_vM) and the principal stress (s_max) were used for numerical analysis (Ansys 10.0). Results: The full crown under C1 showed higher stress at the tooth-restoration interface than that for laminate veneer, increasing the s_vM in 80% for IPS Empress 2 system, and 220% for Procera AllCeram. For L2, the laminate veneers provided higher s_vM, being 24% higher for the IPS Empress and 62% higher for the Procera. Independently of the restoration and loading condition, the Procera system provided higher s_max. Conclusion: The ceramics restoration increased the s_vM in the adhesive interface, mainly with the Procera system. The total crowns showed higher stress in the adhesive interface under L1. The laminate veneers showed higher stress in L2. The IPS Empress and Procera systems might have different behavior due to their mechanical properties and loading condition. (FAPESP 2006/02336-2)