Abstract
This study compares, by means of the finite element method (FEM), the behaviour of the restorations done with the same material, the same adhesive system and under the action of the same force values applied to four 3-D lower premolar finite element models, representing four different cavity shapes. An extracted lower premolar which presented an abfraction lesion has been used. The restoration was achieved by using etch–and-rinse adhesive systems and Giomers. The premolar was scanned and the resulting sections were processed and converted into a 3D digital format. Thus, a model of finite elements which presented a restored wedge-shaped cavity in the cervical dental area was obtained. Then, by modifying the shape and dimensions, there were created another 3 modified-shape cavities. Forces of different magnitudes (90-150N), exerted at a 45 degree angle on buccal cusp, have been applied. If adhesive system tensile strength is about 25MPa, this limit is reached at 120N only for the third model. For Beautifil FO2 the tensile strength is not reached when maximum forces are applied (150N) and for Beautifil II, the tensile strength is reached only for model 4, when a force of 150N is applied. In order to increase the retention of the abfraction restoration, changing the shape of the cavity should be associated with the use of Giomers and adhesive system with tensile strength exceeding 25MPa.
Keywords: cavity shape; noncarious cervical lesions (NCCL); abfraction; finite element method (FEM); Giomer; adhesive system