[Stress analysis of distal free-end removable partial denture]

The study of the force distribution in distal free-end removable partial denture is complicated by the great difference of biomechanical property between the supporting tissue of the distal free-end removable partial denture, abutment tooth and alveolar mucosa under the denture base. Finite element method (FEM) was used in this study to estimate the effect on the abutment tooth and alveolar mucosa under various load conditions. The model is composed of the second premolar, the first molar and the second molar in acrylic resin teeth with the first premolar serving as the abutment. The stress on the abutment tooth was found reduced by 15% on comparing the load condition 3 (222 newton vertical force on each denture acrylic tooth) with the load condition 2 (222 newton vertical force on the second premolar and the first molar), and it can be further reduced by 22% in comparison to load condition 4 (222 newton vertical force on each denture tooth but shared equally to two occlusal contact points per denture tooth). The maximum displacement of the alveolar mucosa was found adjacent to the load area, and the maximum vertical displacement of the alveolar mucosa at load condition 4 is only 0.015 mm greater than load condition 3. It is concluded that when the number of occlusal contacts in distal free-end removable partial denture is increased and evenly distributed, the load on the abutment tooth will be decreased, with only minor effect on the alveolar mucosa.