The role of hydrated silica, titania, and alumina in inducing apatite on implants

Abstract

Pure soluble silica prepared by a sol-gel method induced bone-like hydroxyapatite formation onto its surface when the silica was immersed in a simulated body fluid (SBF), whereas silica glass and quartz did not. This finding directly supports the hypothesis that hydrated silica plays an important role in biologically active hydroxyapatite formation on the surfaces of bioactive glasses and glass-ceramics, which leads to bone-bonding. Gel-derived titania is also a hydroxyapatite inducer because of its abundant TiOH groups. These results provide further insight into the unique osseointegration of titanium and its alloys. It is suspected that gel-derived titania develops an apatite layer by taking calcium and phosphate from the body fluid, thus producing bone-bonding. Although sufficient AlOH groups may remain in the alumina gel, they do not serve to initiate apatite generation when immersed in SBF. This phenomenon explains the fact that an intermediate fibrous tissue is usually found to separate the alumina implant from bone. One may infer that both abundant OH groups and negatively charged surfaces of gel-derived silica and titania are important for hydroxyapatite induction. material which possesses and/or develops both a negatively charged surface and abundant OH groups in a physiologically-related fluid is most likely to be an efficient apatite inducer. Such materials are suitable candidates to serve as bone-bonding biomaterials.

Biomimetic Coating of Precalcified Ti-6Al-4V Alloy

“…A peak centered at 622 cm -1 , is assigned for OH -bending vibration: liberation mode of HA. It has been claimed that abundant hydroxyl groups on the titanium surfaces are essential to the bioactivity of titanium [31].…”

Effect of Hydroxyapatite on Reaction of Dicalcium Phosphate Dihydrate DCPD) and Fluoride Ion

“…The HA was mixed with DCPD or coated on the DCPD particle. Simulated body fluid (SBF, Kokubo Solution) [9] was selected for the method of the coating of HA.…”

Tensile bond between bone and titanium: A reappraisal of osseointegration

“…An oxide layer on the surface of the titanium implant grows slowly and a titania hydrogel is formed on the surface of the passive layer , Kitsugi et al 1996. Titania gel has many properties in common with, e.g., a silica gel, which forms on bioactive glass and is known to induce epitaxial growth of hydroxyapatite (Bagambisa et al 1993, Li et al 1994.…”