Mechanical characterization of soft-tissue stiffness during mandibular distraction

The purpose of this study was to determine the stiffness of mandibular soft tissues during mandibular distraction, from the perspective of improving distraction devices such as automated continuous distractors. Uncompleted osteotomy was performed on 11 fresh human hemimandibles via a greenstick fracture, to preserve the uplift of the internal periosteum of the mandibular corpus. In order to replicate continuous distraction, direct measurements were performed through a uniaxial quasi-static tensile test. For all specimens, linear regression was applied to the force-displacement curve for a force region of 10-20 N, and the slope extracted. The mean stiffness was estimated to be 9.12 ± 3.56 N/mm. This study is the first to measure directly the stiffness of the surrounding tissues of the human mandibular corpus, and paves the way to the design of a new generation of distractor devices.