Mechanical analysis and geometrical optimization of the restored tooth obtained by indirect method ; Analyse mécanique et optimisation géométrique de la dent restaurée par méthode indirecte

The rehabilitation of dental function following the fitting of prostheses obtained by cemented ceramic restorations is one of the major challenges of restorative dentistry. It is now well established that the ceramic/composite interface has an important significance for the longevity of the restoration and its observation using X-ray µ-CT enabled us to characterize some types of defects within the cement layer (air voids and debonding). The mechanical analysis of the restored tooth considering those defects exhibits their negative influence on the strength of the assembly. The influence of design parameters has also been studied considering a simplified 2D axisymmetric FE model in order to avoid the morphological diversity of real geometries. Results show that the design of the inner shape of the crown (editable within the CAD/CAM process) is mechanically relevant. A 3D finite element study extending to the periodontal ligament has then been realized in order to approach this problem in a more realistic perspective. Results show high stresses near from the cervical margin of the crown, coinciding with a common clinical failure mode. This 3D model was also used in a additional study allowing us to conclude that the geometrical data used in modern CAD/CAM processes are sufficient to develop a mechanical optimization of the restoration design. A reverse engineering method based on the interpolation of B-Spline surfaces on scanned data acquired during clinic procedures is therefore introduced in order to integrate a patient specific mechanical optimization within the digital chain of CAD/CAM processes. ; La réhabilitation des fonctions physiologiques dentaires à l’aide de restaurations céramiques collées est l’un des enjeux majeurs de la dentisterie conservatrice. S’il est maintenant bien établi que la jonction céramique/composite revêt une importance capitale pour la durabilité de l’assemblage, les observations par le biais d’un scanner X-µCT nous ont permis de mettre en évidence plusieurs types de défauts ...