Abstract: PURPOSE: To evaluate the equivalent stress and displacement of maxillary sinus floor mucosa by three-dimensional finite element analysis under different types of maxillary sinus floor. METHODS: Three-dimensional finite element models of three different maxillary sinus floor shapes (shallow concave, deep concave and convex) were established by three-dimensional reconstruction of maxillary sinus bones and mucosa. The process of applying dynamic impact load to the maxillary sinus floor was simulated by using the ejector during maxillary sinus lifting operation, and the biomechanical characteristics of different maxillary sinus floor mucosa during ejection was analyzed. RESULTS: The equivalent stress and displacement of maxillary sinus floor mucosa were deep concave (0.518 90 MPa/0.002 955 mm), shallow concave (0.590 25 MPa/0.003 515 mm) and convex (0.623 56 MPa/0.003 660 mm). In the process of axial displacement of the ejector from 1-10 mm, the stress of the mucosa at the bottom of maxillary sinus increased uniformly. CONCLUSIONS: The equivalent stress level of mucosa is related to the morphology of sinus floor. Under the same load condition, the tension on mucosa increases obviously during internal lifting of convex maxillary sinus floor, which has an adverse effect during internal lifting operation.

Key words: Internal maxillary sinus lift, Base wall fractionation, Three-dimensional finite element analysis, Equivalent force, Equivalent displacement