Abstract:

Objective To compare the biomechanical characteristics of small-angle rotation force versus traditional buccal-lingual force in the extraction of vertically impacted mandibular third molars with single conical roots by a three-dimensional finite element analysis. Methods A patient with a vertical mandibular third molar featuring a conical single root was selected. Spiral CT data were acquired and three-dimensional finite element analysis models were constructed using software including MIMICS, Geomagic Wrap, and Solidworks. ANSYS was utilized to simulate both the small-angle rotation and buccal-lingual forces for tooth extraction. Comparative analyses of the biomechanical characteristics of these two forces were conducted by measuring Von-Mises stress and strain distribution. Results In the small-anglerotation force, high-stress and strain areas of tooth, periodontal ligament, and alveolar bone were predominantly concentrated at the cervical region and the upper half of the root, with a more uniform distribution and a broader horizontal diffusion range compared to the vertical diffusion range. In the buccal-lingual force, high-stress and strain areas were primarily located at the cervical region and the lower half of the root, particularly at the apical area, with a broader vertical diffusion range compared to the horizontal diffusion range. The lingual cortical plate and alveolar bone experienced significantly lower stress in the small-angle rotation force than that in the buccal-lingual force. The overall stress values within the periodontal ligament were markedly higher in the small-angle rotation force, with a more uniform distribution. Conclusion The small-angle rotation force is more likely to tear the periodontal ligament and reduce trauma associated with tooth extraction compared to the buccal-lingual force in surgical extraction of vertically impacted mandibular third molars with single conical roots.

Key words: finite element analysis, mandibular third molar, biomechanics