Healing of donor defect after mandibular parasymphyseal block harvesting: a 6-year computerized tomographic follow-up.

Objectives: A long-term survey on the healing potential of large-sized parasymphyseal osseous defects.

Patients And Methods: Ten patients, subjected to 14 bilateral and 3 unilateral parasymphyseal bone harvesting for alveolar ridge augmentation, were selected for the retrospective chart review. CT scans were performed immediately before bone grafting, before implant insertion, and then once annually for 6 years, and the volumes of the bone defects at the buccal aspect in the healing process were measured using a software program. Volumes from the yearly measurements were then compared statistically.

Results: Volumes of both the intrasurgical defects, 0.77 (0.20) cc and of those in the one-year group, 0.60 (0.26) cc were statistically different from volumes of all the other time intervals (from 24 to 72 months) with all p-values less than 0.002 and 0.004, respectively. The healing of osseous defects in the long-term radiographic survey (6 years) resulted in bony infill of 63%.

Conclusion: For parasymphyseal defects of 0.7 cc, a maximum possible healing of two-thirds can be expected; a re-harvesting procedure could be performed 24 months after early surgery, due to both the formation of a new buccal cortical plate and the achievement of a steady state of osseous remodelling.