Morphological factors of mandibular edentulous alveolar ridges influencing the movement of dentures calculated using finite element analysis

Purpose: The aim of this study was to determine the importance of each morphological factor of edentulous alveolar ridges according to its influence on the movement of complete dentures.

Methods: The shapes of casts and waxed complete dentures were digitized. The determined shapes of the ridges were uniformly divided circumferentially and radially. Principal component (PC) analysis was performed using the coordinates of the points on the grid as the variables (morphological PC). The denture movement under bilateral and unilateral loads was analyzed using a finite element (FE) model constructed from the digitized shape, following PC analysis of the displacement of representative points on the denture (displacement PC). The effects of the morphological PCs were evaluated by means of stepwise multiple regression analysis with displacement PC as a dependent variable.

Results: The ridge height, clearance between the ridge and the occlusal plane, and various inclinations, were significantly selected as independent variables where the dependent variable was the displacement PC under a bilateral load. Under a unilateral load, the displacement PC was mainly influenced by the ridge height. The influence of morphological PCs of the non-loaded side tended to be larger than that of loaded side.

Conclusion: Under a bilateral load, ridge height, clearance to the occlusal plane, and inclination of the ridge are considered to account for denture movement. To evaluate the effect of the ridge morphology on denture movement under a unilateral load, it is effective to determine the partitioned shape together with the height in general.