Restoration of mandibular continuity defects using combinations of hydroxylapatite and autogenous bone: microscopic observations.

The purpose of this investigation was to assess by light, transmission, and scanning electron microscopy the healing of mandibular continuity defects reconstructed with varying ratios of an alloplastic hydroxylapatite implant material (HA) mixed with autogenous bone (AB). This study reports the microscopic observations of implant and control sites at 6 and 18 months postsurgery. The results confirm the biocompatibility of dense HA granules. Specimens exhibited differing degrees of osseous regeneration that appeared related to the percent composition of HA. At 18 months, 86% and 91% of the HA granules were completely surrounded by bone in those specimens reconstructed with implants consisting of 25% and 50% HA, respectively. In contrast, specimens receiving implants consisting of 75% and 100% HA features osseous encapsulation of 75% and 66% of the granules, respectively. The results of this limited study indicate that dense HA granules mixed with AB in ratios ranging from 3:1 to 1:1 (AB:HA) may be successfully used as a bone extender during reconstructive surgery.