Biomechanical Behavior of Premolar with Different Configurations: 3D-Finite Element Analysis

Objective: The aim of this study was to evaluate the influence of sequential dental structure reduction and root morphology on stress distribution of maxillary-premolar by 3D finite element analysis.

Methods: Intact maxillary-premolar was selected and the enamel/root boundaries were scanned using contact-scanner (MDX-20, Roland, USA) obtaining 3D-stereolithography files were obtained. The enamel and dentin were sequentially revomed by HCl-2% acid solution. The dentin/pulp boundaries were scanned. All 3D-stereolithography files were exported to Bio-CAD software (Rhino3D, Rhinoceros, USA). The volumes of each structure were obtained by NURBS surfaces association. In this software, the periodontal-ligament and polymer-cylinder were created simulating the experimental tests. All volumes were exported to FE software packages (NeiNastran, Noran Engineering, USA and FEMAP, Siemens, USA). The mechanical properties were obtained by literature review. Twenty-eight linear-static-isotropic models were created. The root was designed into four different configurations: single-root, bifurcated in apical, middle and cervical thirds. The coronal portion was design into six configurations: intact (In), occlusal (Oc), disto-occlusal (DO), mesio-occluso-distal (MOD) cavities, endodontic access (EA) and composite resin restoration (CR). A 200N-loading was applied on buccal and lingual cupids. The stress distribution was analyzed by von Mises criterious.

Results: Stress levels were higher on internal angles of DO, MOD and EA models: 26MPa, 40MPa and 44MPa, respectively. The model Oc presented 5MPa in these angles. The model In presented similar behavior to CR model, with high stress level at 30MPa on cervical region. The bifurcated models produced high stress concentration on angle between roots. The highest stress concentration was found in MOD preparation of tooth with cervical bifurcation (40MPa on cervical region).

Conclusion: The reduction of dental structure promoted high stress concentration inside the dental structure, mainly in lingual cupids. The proximity of bifurcation with coronal portion increases the stress concentration. Root morphology influenced on biomechanical behavior of maxillary-premolar.