Assessment of stress and micromotions using finite element analysis along both the intraoral and the extraoral distractors devices used in the mandibular distraction of post temporomandibular joint ankylosis deformed mandible patients. The process of finite element analysis was carried out to assess distraction models. The first model was an extraoral mandibular distraction model and the second model was an intraoral mandibular distraction model. To analyze the stress state, 2 vertical loads were applied on the defective and normal side respectively by a 3D finite element ball model. The intraoral system observed lower stress (4.5 MPa) in the mandibular bone compared to the extra-oral system (11.5 MPa). The results revealed that the intraoral system observed higher stress on the distractor fixing points (392.21 MPa) compared to the extra-oral fixing points (12.62 MPa). The results revealed that the extra-oral system reflected higher displacement on the bone surrounding the screws of about 3720 mm compared to the intraoral system 1414.6 mm. Internal devices give better shielding to the bone and induce fewer stresses over the mandibular, so it is more advisable to be used. The external devices permit greater distraction length because the pins and the distractor main body are subjected to fewer stresses.

The study group patients have been treated with 1.6 microplates at the superior border and 2.0 miniplate at the inferior border to evaluate its efficacy in the fixation of symphyseal and parasymphyseal fractures using this technique. The control patients were treated with two 2.0 plates. The stability was assessed using computed tomography immediately performed postoperatively and after 6 months. Assessment of the change in the intercanine distance using the Student T test was statistically Non Significant (P value 0.34). The change of intercanine distance in the study was 0.04 ± 0.05 mm, compared with that of the control, which was 0.01 ± 0.03 mm. Assessment of change in intermental foramina distance was statistically NS (P value = 0.06). The average difference in intermental foramina distance in the study was 0.04 ± 0.05 mm, compared with the control, which was 0.002 ± 0.004 mm. Based on the findings of the current study, the authors recommend the use of microplates combined with miniplates in the correction of both symphyseal and parasymphyseal fractures successfully.