Residual Ridge Resorption in Mandibular Kennedy Class I Denture Wearers: Proposal of a Pressure-Induced Mechanism Based on a Finite Element Analysis

Removable partial dentures (RPDs) have been considered an acceptable cost-effective solution to restore oral function in partially edentulous patients. However, in mandibular Kennedy class I patients, the RPDs present unfavourable prognosis due to the combined tooth-mucous support with no posterior elements of retention and continuous resorption of the residual ridge. This process is inevitable but highly variable from one individual to the other and modified by both uncontrollable factors and functional or prosthetic factors that determine load distribution and might be subject of modification by the professional. Using the finite element method, the present study performed a biomechanical analysis of a mandibular distal extension removable partial denture regarding prosthesis displacements, strains in the supporting bone and pressure in the mucosa. The results suggest that bone resorption in the alveolar regions is a strain-mediated process whereas in the edentulous areas it is a process induced by pressure in the mucosa.