The goal of the present study was to verify the resistance to displacement of six different miniplate fixation methods after sagittal split osteotomy.

Methods: Sagittal osteotomy was performed in 30 polyurethane synthetic mandible replicas. The distal segments were advanced (4 mm) and specimens were grouped according to the fixation method: Group 1: four-hole standard miniplate; Group 2: four-hole locking miniplate; Group 3: six-hole standard miniplate; Group 4: six-hole locking miniplate; Group 5: six-hole standard sagittal plate, and Group 6: six-hole locking sagittal plate. Biomechanical evaluation was performed by applying compression loads to three points on the second molar region, using an Instron universal testing machine until a 3-mm displacement of the segments was detected. The compression loads able to produce 3-mm displacement were recorded in kN and subjected to analysis of variance ( P < 0.01) and to Tukey tests for comparison between the groups ( P < 0.05).

Results: The locking sagittal plate showed higher resistance to displacement than the regular four- and six-hole standard plates. No significant differences were observed between the locking sagittal plate and the regular sagittal or the four-hole locking plates. Two among the three groups with the best results had locking plates as the method of fixation.

Conclusions: Fixation of sagittal split osteotomy with a single miniplate is better accomplished by using six-hole locking sagittal plates, six-hole standard sagittal plates, or four-hole locking plates, since these methods are more resistant to displacement.

Conflict of interest: None declared.