Enhanced bone bonding of hydroxyapatite-coated titanium implants by electrical polarization

Hydroxyapatite (HAp) coatings are applied to orthopedic and dental implants made of titanium (Ti) and its alloys in order to increase their bioactivities and to offset the mechanical weakness of HAp. We examined the in vivo effects of electrical polarization on the bone bonding of HAp-coated Ti. Polarized samples with a negatively or positively charged HAp-coated surface (N- or P-surface, respectively) were randomly implanted in the femora and tibiae of canines. As controls, nonpolarized HAp-coated Ti substrates with 0-surfaces were implanted. Direct bonding between the newly formed bone and HAp-coated Ti was observed with the O-, N-, and P-surfaces. The results of a pullout test were consistent with the amount of newly formed bone bonded directly to the surface of HAp-coated Ti. Electrically polarized HAp-coated Ti substrates, especially those with N-surfaces, exposed to recipient bone enhance bone bonding and could enable earlier weight-bearing loads after operations.