LAUSR

Purpose The aim of this study was to investigate the effects of tooth root inclination and crown preparation angulation on the stress distribution of tilted second molars, supporting structures and adjacent implant by using the finite element analysis method. Materials and Methods 3D finite element models of tilted second molar and tooth-supporting structures, including the two designs with three different angles of root inclination and crown preparation angulations, were constructed for full-crown restoration. For all models, the stress distribution was analyzed under vertical and oblique loading conditions. Results The maximum equivalent stress (MES) increased as root inclination increased, and the highest stress value occurred in the tooth root furcation of the model with 30° root inclination under oblique loading. When root inclination was the same, the MES of each structure was approximate under the same direction load regardless of crown preparation angulation. Higher stress values were found on the tooth root, periodontal ligament, and cortical bone of all models under oblique load compared with vertical load. The highest stress value occurred in the distal adjacent area of implant. Conclusion Tooth roots with less than 30° inclination, occlusal preparation parallel to the bite plane and small oblique force loading are recommended as significant considerations for full-crown restoration of a mesial inclined mandibular second molar.