The influence of the number of loaded teeth on the distribution of occlusal vertical forces in onesided dental bridges with one distal cantilever

Abstract

Aim: The paper aims to analyze the distribution of occlusal vertical forces on the abutment teeth in singlesided dental bridge constructions, in slightly shortened dental arches with one distal extension/cantilever, depending on the number of occlusal units. Materials and methods: In five mathematical models with a slightly shortened dental arch in the lower jaw, a single-sided dental bridge was constructed with 5 abutment teeth and one distal cantilever. A finite element method (FEM) was applied. Occlusal loading was done with simulated occlusal vertical forces of 0.5- 512N. Forces were applied on the occlusal surfaces of the teeth. The loading was done as follows: in Model 1 – on the distal cantilever, in Model 2 - on the distal cantilever and the distal abutment tooth, in Model 3 - on the distal cantilever and the two distal abutment teeth, in Model 4 - on the distal cantilever and the three distal abutment teeth, in Model 5 - on the distal cantilever and all abutment teeth. Distributed forces are measured at the level of the periodontal ligament (PDL). Results: The percentage comparison of distributed forces on the abutment teeth in the examined models 1, 2, 3, 4 and 5 indicates a different distribution of occlusal vertical forces between the models. The most even distribution of the percentage of occlusal vertical forces was observed in model 5, followed by Model 4 and Model 3, while the most unfavorable distribution was noted in model 1 and model 2. In all 5 models, the highest percentage of force is distributed on the distal abutment tooth, with the highest percentage noted in model 1. As the number of loaded teeth increases in models 2, 3, 4 and 5, the percentage of distributed force decreases with the lowest percentage of distributed forces found in model 5. There is a significant difference in the distributed forces percentage values on the distal abutment tooth in model 1 and model 5. In Model 1 it ranges from 92.39% to 148.45%, and for Model 5 from 38.09% to 48.02%. In Model 5 and model 4, the direction of the distributed force in all teeth aligns with the direction of the applied force, which means that the fixed construction in models 4 and 5 is the most stable. Conclusion: The percentage of distributed forces on the abutment teeth is in correlation with the number of teeth loaded. In order to achieve a well-balanced, single-sided dental bridge construction in slightly shortened dental arches with one distal cantilever, the occlusal load must be applied on at least three distal abutment teeth.