An In Vitro Comparison Study of the Use of a Drill or a Saw in the Hunsuck-Dal Pont Modification of the Obwegeser Sagittal Split Osteotomy in Pig Mandibles

Purpose: Fracture lines in unfavorable locations are referred to as "bad splits" in a mandibular sagittal split osteotomy (SSO). Several modifications of the technique by Obwegeser have been introduced to minimize this risk. This in vitro study was performed to determine whether the shape of the osteotomy cut affects the torque and the fracture pattern of an SSO in pig mandibles.

Materials and methods: In a split-mouth model, 16 mandibles were split according to the Hunsuck-Dal Pont modification of the Obwegeser technique. Using an oscillating saw, sharp-edged osteotomies were created on one side of the mandible and round-edged osteotomies were created on the contralateral side using a Lindemann bur. Torque forces were measured during the splitting, and the lingual fracture pattern of each split was classified.

Results: Torque forces were significantly (P < .05 by paired t test) decreased by 0.77 N-m (15.6%) when a saw was used for the osteotomy. In the 2 groups, fractures were produced along the mandibular canal. The mandible was more often completely fractured, including the lower mandibular border, when the fracture was created with an oscillating saw (P = .06 by Pearson χ² test). No correlation was found between the torque used and the fracture pattern.

Conclusion: Compared with round-edged osteotomies, sharp-edged osteotomies in pig mandibles facilitated the Hunsuck-Dal Pont modification of the Obwegeser sagittal splitting procedure and produced predictable results with decreased torque.