Effects of non-carious cervical lesions and coronary structure loss association on biomechanical behavior of maxillary premolars

Introduction: Dental lesions and cavity preparations can impact the biomechanical behavior of teeth due to tooth structure loss. Objective: Analyze the influence of tooth structure loss associated to non-carious cervical lesions (NCCLs) and coronary preparations on biomechanical behavior of maxillary premolars, restored or not, using finite element analysis (FEA). Material and methods: Virtual models were generated using a longitudinal cut image of a maxillary premolar, exported to a finite element software (Ansys 12.0) and analyzed as follows: sound tooth (S); MOD preparation (P); MOD preparation restored with composite resin (PR); cervical lesion (L); cervical lesion restored with composite resin (LR); and combinations, PR+LR; P+L; PR+L; P+LR. The areas corresponding to each structure were plotted and then meshed with eight-node isoparametric plane elements (PLANE183) in accordance to mechanical properties of each structure and materials. The materials and structures were assumed elastic, isotropic, homogeneous and linear, except for enamel and dentin, considered orthotropic. Oblique load (45N) was applied on buccal and palatal cusps, simulating an experimental tooth-sphere contact. Von Mises (VM) and maximum principal stress (S1) criteria were applied for analyzing the results. Results: FEA using VM criterion revealed similar stress distribution patterns for groups S, PR, LR and PR+LR. Models L, P+L, P+LR and PR+L presented the highest stress at the center of NCCLs, with S1 levels of 0.22, 0.2, 0.25 and 0.31 MPa, respectively. For groups P and P+LR, Von Mises stress concentration was observed at internal angles of preparation and at base of cusps. Conclusion: NCCLs and intracoronal structure loss associated promoted high stress concentration in dental structure and at center of lesion. The load application influenced the stress distribution, and the models of groups restored with composite resin tend to mimic the biomechanical behavior of sound tooth model.