COMPARISON BETWEEN THE RIGIDITY OF BICORTICAL SCREWS AND A MINIPLATE FOR FIXATION OF A MANDIBULAR SETBACK AFTER A SIMULATED BILATERAL SAGITTAL SPLIT OSTEOTOMY

Purpose: This investigation compared the biomechanical stability of th ree bicortical screws with that of a single four-hole miniplate after 5-mm mandibular setback after a bilateral sagittal split osteotomy (BS SO) in cadaver mandibles. Materials and Methods: Thirty human cadaver hemimandibles underwent BSSO followed by two different rigid fixation techniques. AU specimens had no third molar, bony pathology, or eviden ce of mandibular fracture, and there was no history of renal disease o r hyperparathyroidism. The specimens were randomly divided into two gr oups. In group I, three bicortical screws were placed at the superior border, and in group II, one four-hole miniplate was secured on the ex ternal oblique ridge with four monocortical screws. The bony height of the mandible was recorded. Maximum resistance load (MRL), the greates t load recorded just before a sudden decrease in load level (bone or f ixation failure), was recorded when the mandibles were tested in a com pression machine. Multiple regression analysis was used to evaluate th e differences in bone height and the MRL between groups I and II. Resu lts: The mean bone height in groups I and II were 28.64 +/- 2.50 mm an d 28.72 +/- 4.08 mm, respectively. The mean MRL in group I (20.43 +/- 7.22 kg) was greater than in group II(17.41 +/- 7.81 kg). The multiple regression analysis showed no significant difference in the bone heig ht and the MRL between group I and group II (beta = 2.3492, P = .4114) . Conclusion: There was no statistically significant difference in sta bility provided the two techniques.