Purpose: Highly crystalline thin hydroxyapatite (HA) layers deposited on the surface of commercially pure titanium (cpTi) by discharge anodic oxidation and hydrothermal treatment (SA treatment) enhance the value of cpTi as endosseous implant material in clinical dentistry. The SA treatment in particular is important for the osteoconductive properties of cpTi. However, it is crucial to ascertain whether the HA layer retains its chemical stability during osseointegration. This study characterized the morphological, chemical and structural features of HA layers during in vitro bone matrix mineralization.
Materials and Methods: SA-treated cpTi disks were used in this study. Rat bone marrow stromal (RBM) cells were obtained from Wistar rats and cultured on SA-treated cpTi disks for 5, 7, 10, and 14 days. The thin HA layers of these samples were analyzed by electron probe microanalysis (EPMA), scanning electron microscopy (SEM), thin-film x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS).
Results: EPMA revealed an even distribution of P and Ca during all culturing periods. SEM and XRD analysis showed that the morphology or crystalline features of the thin HA layer were not altered during culturing. The XRD patterns showed a characteristic HA formation and peak that did not change with the length of time in the culture in comparison to the control samples. Finally, the XPS analysis indicated no change in the binding energy of P and Ca in the HA crystals among all the cultured samples and the control.
Conclusion: The thin HA layer formed on the SA-treated cpTi disks appeared to remain stable during the process of bone matrix mineralization.