Vertical augmentation using autogenous block bone and synthetic hydroxyapatite block without fixation on rabbit calvaria

Abstract

Purpose: The preferred material for bone augmentation beyond the envelope of skeletal bone is the block bone graft, due to its dimensional stability. We evaluated the necessity of rigid fixation for the block bone graft, and compared the bone regeneration and volume maintenance associated with grafting using a synthetic hydroxyapatite block (HAB) and an autogenous block bone (ABB) without rigid fixation on rabbit calvaria over two different periods.Materials and methods: Cylinder-shaped synthetic HAB and ABB were positioned without fixation on the rabbit calvarium (n=16). The animals were sacrificed at 4 and 8 weeks postoperatively, and the grafted materials were analyzed at each healing period using microcomputed tomography and histologic evaluation.Results: Integration of the graft and the recipient bed was observed in all specimens, although minor dislocation of the graft materials from the original position was evident in some specimens (Six ABB and ten HAB samples). A tendency toward progressive bone resorption was observed in the grafted ABB but not in the grafted HAB, which maintained an intact appearance. In the HAB group, the area of new bone increased between 4 and 8 weeks postoperatively, but the difference was not statistically significant.Conclusion: All of the nonfixed HAB was integrated into the recipient bed after both healing periods in rabbit calvaria. In spite of limited bone formation activity in comparison to ABB, HAB may be a favorable substitute osteoconductive bone material.