Biomechanical Effects of mandibular symphyseal distraction: A Three-Dimensional FEM-Analysis

Objectives: The aim of this study was to evaluate the biomechanical effects of mandibular symphyseal distraction by bone anchored intraoral device using a 3-dimensional FEM-model, whose construction was based on spiral computed tomographic (CT) scans of a 21-year-old woman. During surgically assisted mandibular expansion a transverse widening of the maxilla is intending between the mandibular incisors.

Methods: Finite Element Analysis (FEA) was performed to depict the physiological changes and stress distribution in mandibular structures and device materials. The final mesh consisted of 3000 solid elements. The distraction was performed on the middle intersection point of the vertical and horizontal planes on the mandibular symphysis. The mechanical response in terms of displacement and von Mises stresses was determined by widening the mandible up to 3mm on both sides. The bordering conditions for FEM analysis were set up dynamically depends from osteotomy and diameter of distraction.

Results: The results indicate parallel mandibular widening with decreased effects from anterior to posterior and a mandibular bone displacement forward and downward. Highest stress levels were observed bilaterally in condylar areas and in ramal region of mandible.

Conclusion: With 3D analyzing of CT-data there is a valid possibility to recognize individual stress distributions in mandibular widening patients using bone borne distraction device. The finite element model therefore represents an individual simulation model to evaluate stress and force distribution in mandubular bone structures.