Finite element method analysis of the stress distribution to supporting tissues in a Class IV Aramany removable partial denture (Part I: the teeth and periodontal ligament).

Objective: Special care is required in the fabrication of a Class IV Aramany removable partial denture (RPD) in order to minimize the stress distribution to supporting tissues. Using the finite element method, the aim of this study was to analyze the distribution stress to supporting tissues when a Class IV Aramany RPD is worn.

Methods: Three RPD designs with circumferential cast retainers were examined in this study. These varied in retainer configuration which included: buccal retention and palatal reciprocation (P1); palatal retention and buccal reciprocation (P2); and buccal and palatal retention (P3). The stress distribution in models using the Von Mises criteria was analyzed for each RPD design when placed under a 53N load from three different directions that included: vertical to the posterior teeth of the RPD (F1); at a 33 masculine angle to the posterior teeth of the RPD (F2); and vertically on the anterior teeth of the RPD (F3).

Results: The maximum stress in teeth (91.3 Mpa) was generated when a 53N force was applied vertically from anterior teeth of RPD (F3) using buccal and palatal retention (P3). The maximum stress (0.494 Mpa) in the periodontal ligament (PDL) was also generated under the same conditions using the F3 load on the P3 design.

Conclusions: In all three directions of force application RPDs with buccal and palatal retention induced more stress in the tooth and the PDL with the maximum stress generated when the force was applied vertically to the anterior teeth. The axis of rotation can be changed by altering the RPD design as well as the direction and amount of force applied to the teeth.