Volumetric assessment of the distracted human mandible

The mandibles of five patients who underwent unilateral or bilateral distraction osteogenesis were analyzed using computed tomography scans. The mandibles were reconstructed in three dimensions using General Electric computed tomography software. The total volume of each hemimandible was determined before and after distraction and compared. The mandibles were then segmented at 1-cm intervals, and the volumes of the segments were determined. The volumes of the mandibular segments before and after distraction were compared to determine the distribution of new bone through the mandible and the quantity of bone generated by distraction. The distracted hemimandibles increased in total volume by an average of 19.9% (statistically significant by the Student paired t test; P < 0.0001), whereas the nondistracted hemimandibles increased in total volume by an average of 5.2%. The segmental volumes of the distracted mandible were of similar or greater volume when compared to the preoperative mandibular segments. In addition, the distribution of regenerate bone mirrored the physiological distribution of the preoperative mandibular bone. This study indicates that distraction not only creates new bone but distributes that bone through the remodeled mandible in an anatomical pattern similar to that of the preoperative bone.