Purpose : This study aimed to evaluate bone remodeling at the site of bone harvesting in the mandibular symphysis radiographically.
Materials and Methods : We assessed the sites where bone was harvested from the mandibular symphysis in 10 patients who required bone augmentation, over a period of 7 years from April 2005 to March 2012. The appropriate bone volume was harvested from the mandibular symphysis using a #701 fissure or trephine bur, under abundant saline irrigation. The lingual and inferior cortex bone was maintained where possible, and the wound underwent primary closure.
Observations and Measurements : We observed the bone surface before and after bone harvesting during the surgery, and measured the bone widths from the reference point on the lingual cortex bone to the labial bone surface at 0.5-mm intervals. For cases where more than 2 years had elapsed after surgery, the condition of the bone was evaluated from cone-beam computed tomography (CT) images, mainly obtained by cross-sectional cone-beam CT of the dental arch.
Results : The CT images revealed marked bone reformation at the concave bone harvesting sites by 6 months after bone harvesting surgery. Thereafter the volume of reformed bone volume gradually decreased, and the changes plateaued by approximately 1 to 2 years. The sites where bone was harvested developed a concave surface, sloping downward from the bone margin toward the center of the site. The labio-lingual bone width measured 5.5-11.5 mm (mean : 9.6 mm) before bone harvesting, 1.5-4.5 mm (mean : 3.0 mm) immediately after bone harvesting, and 4-10 mm (mean : 7.2 mm) more than 2 years after the surgery.
Conclusion : Up to 64% of the harvested bone volume was remodeled over a period of more than 2 years after bone harvesting surgery. The remodeled area formed a sloped concave surface within the margin of the bone harvesting area.