Journal of Dental Research, Vol 70, 1346-1349, Copyright © 1991 by International & American Associations for Dental Research Online Journals
Induction of calcium phosphate precipitation by titanium dioxide
J. J. Damen, J. M. Ten Cate and J. E. Ellingsen
Department of Cariology and Endodontology, Academic Centre for Dentistry Amsterdam, The Netherlands.
Titanium powder and various titanium dioxides were tested for their
capacity to reduce the induction time for calcium phosphate precipitation
from supersaturated solutions. Only after a pretreatment aimed at
increasing its oxide surface layer was titanium powder found to accelerate
the precipitation from solutions containing 2 mmol/L CaCl2, 2 mmol/L
KH2PO4, 50 mmol/L Hepes, pH 7.2, and to induce precipitation from
metastable solutions containing 1.2 mmol/L CaCl2, 1.2 mmol/L KH2PO4, 50
mmol/L Hepes, pH 7.2, at 37 degrees C. Even stronger effects were found
when suspensions of the titanium dioxides anatase or rutile (10-50
micrograms/mL) were added to these solutions. TiO2 appeared to serve as a
reactive substrate for secondary nucleation at a wide range of
calcium-to-phosphate ratios and concentrations, even in the presence of 40
mg/mL bovine serum albumin, which completely inhibited precipitation in
control incubations. These results suggest that the oxide surface layer of
titanium implants may induce calcium phosphate precipitation in the
metal-to-bone interface, which may play a role in the integration of such
implants in bone.
