A Torque Removal Study on the Primary Stability of Implants with Hydroxyapatite Thin Film Grown by Pulsed Laser Deposition

Abstract

Objective: Since the hydroxyapatite film of hydroxyapatite-coated implants fabricated using plasma spraying is thick and shows low crystallinity, its in vivo fracture or detachment due to factors such as occlusal force has been reported. Therefore, these implants are not widely used at present.
Methods: To improve this situation, our research group developed implants coated with a thin hydroxyapatite film (thickness ＜1 μm) employing a laser ablation method (pulse laser deposition technique: PLD). In this study, the bone-bonding strength of implants coated with a thin hydroxyapatite film produced using PLD was evaluated in dogs.
Results: A longitudinal increase both in the removal torque of implants coated with a thin hydroxyapatite layer and titanium implants was recognized by two-way analysis of variance (ANOVA)(p＜0.01). There were significant differences between the removal torque of implants coated with a thin hydroxyapatite layer and titanium implants, and the removal torque of implants coated with a thin hydroxyapatite layer 12 weeks after placement was significantly higher than that of titanium implants (p＜0.05) .
Conclusion: The results suggest that thin-layer hydroxyapatite can contribute to the fixation after implant placement, allowing early loading.