Spontaneous bone regeneration after segmental mandibular resection: a retrospective study of 13 cases.

The aim of this study was to evaluate the clinical characteristics of cases of spontaneous bone regeneration of the mandible after segmental resection. This retrospective study covered a 23-year period and used data obtained from the hospital records; patient data were entered into a pro-forma questionnaire. Overall, the cases of 636 patients with mandibular lesions treated by segmental resection were reviewed; 13 (2.0%) had spontaneous bone regeneration. The time post-surgery at which bone regeneration was first noticed ranged from 9 to 17 weeks. Seven patients were male (53.8%) and six were female (46.2%), giving a male to female ratio of 1.2:1. The patients ranged in age from 16 to 51 years (mean 26.6±3.6 years). The periosteum was completely excised after resection in eight patients (61.5%), while it was partially preserved in five (38.5%). The younger the patient, the earlier the spontaneous bone regeneration occurred in the defect (P=0.001), particularly in those who had complete excision of the periosteum. Radiographically, the new bone formed was observed to have the same appearance as the cortical bone of the mandibular stumps, but lacked height. This study suggests that bone graft reconstructions may still be necessary for this group of patients who show spontaneous bone regeneration.