The Stress Concentration and Biomechanical Properties of the Intraoral Distractors and the Extraoral Distractors Used in Treatment of Hemifacial Microsomia Patients: A Simulation Finite Element Analysis Study.

The Aim Of The Study: Finite element analysis of the stresses subjected to both the intraoral and the extraoral distractors devices used in the mandibular distraction of hemifacial microsomia patients.

Methodology: Two models were included in the current study. The first model was an extraoral distractor and the second model was an intraoral distractor model. To generate the results in the simulated models; 2 vertical loads were applied (222.7 and 137.78 N) on the defective and normal side, respectively.

Results: The intraoral system observed lower stress (6.85 MPa) in the mandibular bone compared to the extraoral system (13.21 MPa). The intraoral distractor had a higher stress concentration on the distractor fixing screws (352 MPa) compared to the extraoral distractor fixing pins (15 MPa). The extraoral distractor had a higher displacement effect on the mandibular bone around the pins of 263.35 μm in comparison to the intraoral distractor effect which was 77.87 μm.

Conclusions: Internal oral distractor provides a sort of stress shielding to the distracted bone and less displacement, so it is more advisable to be used in general. The external devices are advised only in extralong distraction distance because the distractor is subjected to lower stresses compared to intraoral counterparts.