Dentin stresses from simulated functional loads to post-reinforced tooth models with four levels of periodontal support were calculated using finite element analysis. As bone levels diminished, stresses were found to increase dramatically and to concentrate in the small amount of dentin remaining near the post apex.

A theoretical investigation has utilized the finite element technique to analyze mechanical stress patterns in a reconstructed maxillary central incisor. A series of designs for endodontic dowel posts incorporated into prosthesis has been comparatively evaluated. For the load condition considered, the results show that minor changes in the stress patterns are produced by the post diameter, length, and taper variations considered. 1. In general, larger post diameters decrease the maximum stresses for both the cylindrical and tapered designs. Variation of diameters over a 15% range produced stress variations of about 8%. 2. The effect of post length on the highest stresses in bending was less than the diameter changes. The real effect of the length changes was to change the location of the stress concentrations that occurred at the post apex in all cases. 3. The effect of taper was found to be slight if the local tapered-post diameter was comparable to the cylindrical post diameter in the high-stress region. 4. For the load considered in this study, the tapered-post design experienced slightly higher tensile and slightly lower shear stresses than the cylindrical post. 5. Using the peak stresses in the dentin and at the dentin-post interface as a criterion, the cylindrical post with the largest diameter is the best design among those examined.

No abstract

Mechanical stresses in the periodontal ligament which help initiate the lesion of occlusal trauma have been difficult to evaluate. The purpose of this study was to use a mathematical system (finite element analysis) to calculate principal periodontal ligament stresses in primary and secondary occlusal trauma. Maxillary central incisors were modeled in periodontal tissues representing four levels of bone support. Models were partitioned and subjected to three simulated functional loads. Stresses were calculated at multiple nodes in the periodontal ligament adjacent to root and bone. Results showed areas of greatest compressive stress near the alveolar crest and in the apical one‐half of the root for all loads at all bone levels. Stress curves correlated well with the histologic lesion of occlusal trauma. Centric contact loads (P3) consistently produced less ligament stress than protrusive contact (P1). Reduction of alveolar bone height had little effect on the degree of periodontal ligament stress until six millimeters (60%) of bone support had been lost. Finite element analysis provides a convenient model for the study of the mechanical component of occlusal traumatism.