Biomechanical impact during protrusion loading on an incisor restored with a ceramic crown

The fracture resistance of all-ceramic restorations is one of the major concerns in clinical applications of these materials. Finite element analysis is usually applied in the studies of this area without considering changes in contacts with the antagonists teeth during the occlusal movements. A 3D model of a incisor was created: intact teeth, unrestored teeth; the same teeth restored with full ceramic crown. A virtual analysis of the protrusion was carried out and a trajectory path was designed and divided in 6 areas. The contact areas were visualized and loaded separately. Stress distribution of the restored incisor during protrusion stages was analyzed. These were exported in Ansys finite element analysis software for structural simulations. In the crowns the stresses were distributed around the contact areas with the antagonists and in the cervical areas. Regarding the stress distribution in the prepared teeth, the areas were larger around the marginal line, especially under the line. The biggest disadvantage is that high stresses are present around the marginal areas. During protrusion and moving of the contact area incisaly, the maximal values of the stresses increase and also the stress areas become grater in the oral part of the crown. Considering changes in contacts with the antagonists teeth during the occlusal movements is very important for a biomechanical analysis. Key-Words: ceramic crown, incisor, protrusion, finite element analysis, stresses.