Human bone repair after mandibular symphysis block harvesting: A clinical and tomographic study

Background: There are limited data on the healing potential of osseous defects in the human mandible. Animal model studies have shown that defect fill is size dependent. Methods: Twenty patients who had autogenous block transplants harvested from the mandibular symphysis were included in the study. Computerized tomography (CT) scans were carried out at an average of 26.7 months after augmentation to assess bone healing. Subgroups were compared on the basis of bone volume harvested, healing time, incision design, symphysis midline preservation, age, and gender. Percentage bone fill was calculated by comparing the preoperative and postoperative CT scans using a computer software program. Results: CT scan analysis showed a significant percentage (74.5%±10.36%) of bone fill at an average of 26.7±22.3 months (range, 4 to 72 months). Healing time and bone volume harvested were significant variables influencing the osteogenic potential of mandibular donor-site defects. Defects <0.5 cc with a healing period of 34.2 months showed 81%±7.4% bone fill, whereas those >0.5 cc and 7.2months of healing had a repair of 63.8%±12.2% (P <0.05; 95% CI, 2.46 to 31.93). A positive trend in bone fill was observed for subgroups receiving sulcular incisions (80%) and midline preservation (77.5%). Conclusions: The osteogenic potential of human osseous repair in the mandibular symphysis is size and time dependent. The process of osteogenesis of repair in humans seems to be multifactorial. Such factors as preservation of the periosteum and symphysis cortical midline may positively influence defect fill allowing for reharvesting.