Coexistence of horizontal bone loss and dehiscence with the bundle and conventional fiber post: a finite element analysis.

Horizontal bone loss (HBL) and dehiscence are common supportive tissue defects. This study evaluated the stress distribution in the presence of HBL or dehiscence and two types of fiber posts. Twelve premolars that were endodontically treated (Model-E), restored with conventional (Model-C), and bundle (Model-B) post were modeled. Bone defects were created as control (Model-1), with 4 mm (Model-4) and 8 mm (Model-8) HBL, and dehiscence involving two-thirds of the root (Model-D). HBL was included in all aspects of the models, while dehiscence was confined to the buccal aspect. The models were subjected to a 200 N force, and von Mises stress was analyzed. Model-B1 showed higher stress than Model-C1 but was more homogeneous. In Model-D, the stress was limited to the area without bone and only occurred at the buccal aspect. The highest stress was observed in Model-B8. The presence of a post caused a 2-5.8 times increase in stress. When the crown-root ratio was 1:0.8, stress was in the coronal two-thirds of the root, while at a ratio of 1:0.3, stress was distributed throughout the entire root. Bundle post with 8 mm HBL increased the stress 5.8 times. HBL resulted in stress extending beyond the marginal bone, while dehiscence did not.