Effect of pontic width on stress distribution in abutment teeth and their supporting structures by finite element analysis

Fixed partial dentures and single restorations reveal differences in the pattern and quantity of stress. The most important factors affecting stress distribution in abutments are occluso-gingival height and bucco-lingual width. In this in vitro study a finite element analysis was performed to evaluate changes in the pattern and quantity of stress in pontics with different widths. Three PFM models were created, one with a conventional width and the other two demonstrating 20% and 40% width-reduction. The models were fabricated to replace a mandibular first molar. A load of 700 N was applied vertically to the center of the pontic and the stress patterns were examined by finite element analysis. Maximum stress concentration was observed in the supporting bone of the abutment teeth mesial to the premolars, distal to the molars and in the apical portions of the premolars. The 20% and 40% width-reduction of the pontics caused a similar amount of stress reduction in the supporting tissues of the abutment teeth. Stress concentration sites were also observed at the furcation area and the cervical regions of the distal aspect of the premolars and mesial aspect of the molars. The reduction in stress values within tooth structure was proportional but less than the 20% and 40% width-reduction of the pontics. Reduction of pontic width caused a considerable amount of stress reduction in the supporting bone and a smaller amount in tooth structure.