Patterns of bone induction by coral-derived vs highly sintered crystalline hydroxyapatite constructs

Abstract

Aim: To evaluate the morphological patterns of bone induction by coral-derived vs highly sintered hydroxyapatite constructs. Methods: Twenty-eight (28) histological slides of harvested tissue samples from the rectus abdominis muscle of adult baboons of both coral-derived and highly sintered hydroxyapatite specimens were histologically examined to describe the induction of bone formation along the macroporous spaces of the hydroxyapatite (HA) substrata and the development of osteoblast-like cells within the mesenchymal condensations. Results: Two specific tissues characterized the tissue invasion within the macroporous spaces of the coral-derived hydroxyapatite constructs, namely, 1: cellular connective tissue matrix penetrated by sprouting capillaries and 2: mesenchymal collagenous condensations that differentiated and attached to the surface of the coral-derived substratum. To the contrary, in the highly sintered constructs, the mesenchymal cellular condensations could not be detected. Fibrovascular tissue was richly invaded by blood vessels almost in direct contact with the sintered hydroxyapatite interface. Elongated spindle-shaped-like cells localised within the mesenchymal collagenous condensation. The main histological feature that characterised the induction of bone formation by coral-derived hydroxyapatite implant was the induction of mesenchymal collagenous condensation.

In all harvested specimens of highly sintered hydroxyapatite, the initiation of bone formation formed directly against the hydroxyapatite interface without formation of mesenchymal collagenous condensations at the sintered hydroxyapatite interface. Conclusion: The results obtained from this study further support the concept of construction of solid geometric calcium phosphate osteogenic devices in controlling the induction of bone formation for the treatment of multiple periodontal osseous defects in human patients.