Three-dimentional finite element analysis of a mandibular premolar with reduced periodontal support under a non-axial load

Abstract

This study analyzed stress profiles of a mandibular premolar and its supporting periodontium under non-axial occlusal load as a function of the level of periodontal bone support using finite element analysis (FEA) and compared biomechanical behaviors to the profile under axial loading. A composite three-dimensional FEA model of a lower second premolar and its supporting tissue was developed using scanned image and computed tomography (CT) data. Material properties for enamel, dentin, periodontal ligament (PDL), and alveolar bone were used in this analysis. Four levels of periodontal support were simulated by varying the bone level, and a 90 N load was applied axially on the buccal cusp or 45° non-axially on inner inclines to simulate vertical or lateral forces. Finally, the von Mises stress (VMS) was calculated using FEA software. The non-axial load resulted in a peak VMS at the cervical enamel region, regardless of the bone level, and in extensive concentration of the peak VMS at the root dentin, PDL, and bone crest opposite to the loading direction, which increased with decreased periodontal bone support. The stress concentration along the root and PDL to the non-axial load shifted apically with periodontal bone support decrease. In the PDL and alveolar bone, the increase in peak VMS was significant with less than half of the bone height. Non-axial occlusal loads present asymmetric stress distribution in root dentin and PDL at the crest level, depending on the loading direction, with a significant increase in severe bone reduction (≥50%). The periodontal bone support decrease shifts the peak stress apically away and can result in apical extension of the root defect.