Comparative study of biomechanical stability of resorbable and titanium fixation systems after sagittal split ramus...

Sagittal split ramus osteotomy (SSRO) is one of the most popular surgical procedures for correction of mandibular deformities. Several clinical and biomechanical studies exist in the literature which, comparing the stability of different osteosynthesis materials and techniques, were performed using two or three-point biomechanical test models. The aim of this study was to compare the stability of biodegradable and titanium materials for SSRO on one-piece polyurethane mandible samples which were fixed in a novel designed 6-point testing unit.

16 polyurethane one piece replicas of human mandibles were used and bilateral SSRO were performed by the manufacturer according to Dal Pont modification. Mandibles were fixed with titanium and PLLA/PGA fixation materials. Displacement amounts were measured under loading forces using a non-contact extensometer, and strain values at the screws were recorded by strain gauges.

Bicortical titanium screws (Group 2) showed significantly lower displacement values, while bicortical PLLA/PGA screws (group 4) showed significantly higher displacement values at 40-360 N forces. (p < 0.05). The highest strain value was measured on screws that were inserted upright in a proximal segment near the osteotomy line.

To achieve more realistic results in biomechanical studies, test models should imitate jaw movements and test environments should be as similar as possible to physiological conditions. Newly designed six-point testing units will contribute to future biomechanical studies.