Determination the most appropriate stress distribution in fixation of mandible with resorbable plates and screws after BSSRO surgery-FEA study

Due to the complications associated with fixation by titanium screws and plates in BSSRO surgery, the use of resorbable polymers have been increasingly recommended. Since there is not enough studies on this issue through the literature, this study aimed to assess the most appropriate stress distribution in fixation with resorbable plates after BSSRO surgery by FEA This experimental study was performed on simulated human mandible using Ansys and CATIA softwares. The osteotomy line was applied to the simulated model and experimental loads of 75, 135 and 600 N were respectively exerted according to the natural direction of occlusal force. The distribution pattern of stress was assessed and compared for fixation with four-hole resorbable miniplate, two-hole resorbable miniplate and parallel miniplate using Ansys software. Among the four simulated fixations, parallel miniplates showed the highest primary stability. Four-hole resorbable plates were also associated with sufficient primary stability and less trauma and cost for patients. Two-hole resorbable plates did not provide enough stability under 600 N. Polymer-based resorbable plates and screws (polyglycolic acid and D, L polylactide acid) in every three patterns, on masticatory loads after surgery, provides satisfactory primary stability in BSSRO surgery and the displacement of the osteotomy site fixed with this system was inconsiderable. the plates should at least have four holes and adjust in appropriate position (neutral zone) to provide sufficient primary stability. Therefore resorbabale fixation can be a good alternative for titanium fixation in BSSRO surgery.