Histological and histomorphometrical evaluation of porous phosphate glass as a bone graft substitute: A pilot study

Aim To overcome the disadvantages of auto-, allo-, and/or xenografts (XG), porous synthetic bone graft substitutes are considered as suitable alternatives. The aim of this animal study was to determine the bone regeneration potential of a synthetic bioactive porous phosphate glass (PPG) in comparison with a commercially available XG. Materials and methods Defects were created by making 4 mm holes in each rabbit femur and in a cavity of approximately 5 X 8 X 40 (W X D X L) mm(3) made in Beagle dog mandibles after removing the incisors. Empty cavities were used as negative controls in both the evaluation models. Cavities thus made were grafted with the bone grafts (PPG or XG) or kept empty. Histological and histomorphometrical analyses were carried out post-ex-plantation at specific time points. Results Histologically, partial to almost-complete degradation of the grafts was observed in the rabbit femur and Beagle dog mandible models. Bone regeneration was observed within the bulk of the PPG but not in XG particles. Bone regeneration by PPG and XG was histomorphometrically analyzed in Beagle dog mandible model. A higher standard deviation was observed for XG compared to PPG in histomorphometrical analyses at all the healing points. Conclusion The results indicate that PPG is a bone graft that promotes osteoconductivity and bone regeneration when compared to a commercial XG but with better predictability.