Osteodistraction of a previously irradiated mandible with or without adjunctive hyperbaric oxygenation: an experimental study in rabbits

Abstract. The purpose of this study was to analyse the effects of irradiation and hyperbaric oxygenation (HBO) on mandibular osteodistraction (OD). Eighteen rabbits were divided into three groups: 1. Irradiation (R), 2. Irradiation+HBO (R-HO), and 3. Control group (C). Animals of groups R and R-HO received in the mandible irradiation 22.4Gy in four 5.6Gy fractions (equivalent to 50Gy/25 fractions). In addition, group R-HO was given HBO at 2.5ATA for 90min per day 18 times preoperatively. Unilateral osteotomy was made 1 month after completion of radiotherapy. After a 1 week latency period bone distraction was started at rate of 1mm per day, continued for 2 weeks, and left to consolidate for 4 weeks. Amount of new bone was measured histomorphometrically from midsagittal sections. Area of new bone was equal in all groups. Bone was more mature and bone spicules better organized in group C than in groups R and R-HO. Cartilaginous cells were found in distracted bone in all groups but larger chondroid islands were evident only in group R. It seems that despite delayed bone formation, OD can be performed after radiotherapy. HBO had a beneficial effect on bone quality of a previously irradiated mandible.