ANALYSIS OF OSTEOBLAST MINERAL-DEPOSITS ON ORTHOPEDIC DENTAL IMPLANT METALS

Neonatal rat calvarial osteoblasts were cultured on Ti-6Al-4V, Co-Cr-M o alloy, 316L stainless steel and polystyrene (reference substrate) in the presence of ascorbic acid and 10 mM beta-glycerophosphate for 16, 17, 18, 19, 20, 21, 24 and 28 d. Scanning electron microscopy examina tion revealed that osteoblasts cultured on these orthopaedic/dental im plant metals synthesized and deposited an extracellular matrix contain ing collagenous and non-collagenous components, as well as mineral nod ules of various morphologies. Energy dispersive spectrometry revealed that the mineral deposits consisted of three distinct chemical composi tions: calcium phosphate, calcium-sulphur-phosphorus, and calcium only . Backscattered electron imaging demonstrated that both the calcium ph osphate and calcium-only deposits were electron dense, while the calci um-sulphur-phosphorus deposits were electron translucent. X-ray diffra ction analysis indicated that the bulk of the osteoblast mineral depos its was amorphous hydroxyapatite; in addition, electron diffraction an alysis revealed small regions of crystalline hydroxyapatite.