Abstract
Studies have presented fixed partial dentures (FPD) as a good alternative in the treatment of missing teeth in both bounded and unbounded cases. Most of the biomechanical studies on long unbounded FPDs in the distal extension area have focused on the Von-Mises stress distribution developed in bone as a result to the applied load. Another parameter, not sufficiently addressed, is the load transmission mechanism responsible for the above-mentioned stresses. The purpose of this study, therefore, is to focus on the forces transmitted from the denture to the underlying bone and their effects on the carrying teeth as well as the prostheses. Three idealized computer-aided design (CAD) for FPDs supported by one, two, and three teeth were constructed. To further investigate the effect of misfitting the bridge on the patient's jaw, three similar models were also generated in which a small gap is set between denture and mucosa. The corresponding finite element analyses were conducted and results analyzed under a 100N occluso-apical load, located at the free end of the prostheses. Results showed that the load transfer mechanism varied substantially with the number of carrying teeth. When the denture is misfitted on the patients jaw, the teeth are found to carry more load while the mucosa is slightly relieved. Results also showed a substantial upward occlusal (pull out) force on the most mesial tooth while significant apical forces and moments act on the most distal tooth. These observations are more prominent in the case of misplaced denture. The high computed forces and moments may eventually cause tooth loosening and ultimately lead to denture failure, particularly in the later case.