Evaluation of Osseointegration Between Two Different Modalities of Hydroxyapatite Implant Surface Coatings: Plasma Sprayed HA Coated Implants and Electrophoresis Deposited Nano HA Coated Implants

Abstract

Purpose: The objective of this study was to evaluate the osseointegration between plasma sprayed (PS) hydroxyapatite (HA) coated implants and electrophoresis deposited (EPD) nano hydroxyapatite coated implants in an animal model. The quantity of osseointegration was inferred by interfacial strength and percent tissue-contact length.Materials and Methods: Thirty-six cylindrical implants (18 PS and 18 EPD) were placed into dog mandibles. Nine implants from each group were evaluated with pull out testing and histological studies at 12 weeks after implantation. The remaining implants were occlusally loaded for 9 months and then evaluated by pull out testing and histological studies.Results: Twelve weeks after implantation, no statistical difference in pull out strength was observed between PS HA (70.43 ± 16.65 lbf) and EPD nano HA (86.35 ± 28.07 lbf) coated implants . After loading for 9 months, it was observed that the interfacial strength of implants coated by EPD nano HA (199.9 ± 35.1 lbf) was statistically higher (P \u3c0.028) than the PS HA coated implants (121.14 ± 38.45 lbf). At 12 weeks implantation, no statistical significant difference in bone contact length was observed between EPD nano HA (97.6 ± 3.2%) and PS HA coated implants (95.6 ± 4.6%). No statistical significant difference in tissue-contact length was observed between EPD nano HA(91.8 ± 8.2%) and PS HA coated implants (84.3 ± 7.2%) after loading for 9 months.Discussion: The advantages of PS HA coatings are widely recognized, but little data exists on rate and quantity of osseointegration relative to newer coating methodologies such as electrophoresis deposition. EPD nano HA shows promise as a HA implant coating process, achieving higher interfacial strength than the PS HA coating after 1 year in this study. Conclusion: Histological data and interfacial strength suggest that PS and EPD nano HA coated implants achieve similar bone responses short term. However, EPD nano HA coated implants attained a higher interfacial strength after 9 months of loading, even though histological data was not statistically different from that of PS HA coated implants