Background
Clinical research has shown that hydroxyapatite coated implants can improve the outcome of this procedure by enhancing the osseointegration process, decreasing healing time, and increasing the 5-year success rates post procedure.

Aim/Hypothesis 
We conducted a retrospective descriptive study to evaluate the clinical outcomes of two hydroxyapatite (HA) coated implants, OT (Osstem TS III-HA, Osstem implant Co., Busan, Korea) and ZM (Zimmer TSV-HA, Zimmer dental, Carlsbad, USA.

Materials and Methods 
We evaluated 303 implants that were surgically placed by one oral and maxillofacial surgeon at Seoul National University Bundang Hospital, Section of Dentistry from 2010 to 2012, comparing four outcome standards: success rates, survival rates, annual marginal bone loss, and implant stability quotients. The samples were classified into immediate, early, conventional, and delayed groups according to the loading time. They were also classified into 1 and 2-stage groups according to the surgical procedures.

Results 
Overall, there were no significant differences between OT and ZM when comparing success rates, survival rates, and annual marginal bone loss; however, there was a difference in late stability (ISQ). Specifically, ISQ, which occurs after healing, was slightly higher in the in the OT implants (77.83±8.23 vs. 76.09±6.90, P<.05). When analyzing the healing periods between the two implant types, only immediate loading showed a statistically significant difference (P<.05). The OT implants performed better than the ZM implants when comparing annual marginal bone loss (-0.17±0.58 mm/year vs -0.45±0.80 mm/year) and late stability (84.36±3.80 ISQ vs 82.48±3.69 ISQ, P<.05).There were no statistically significant differences in the remaining indices, which were early, conventional, and delayed loading (P>.05). Finally, OT appeared to have slightly better bone loss and late stability than ZM in 1-stage surgery.

Conclusions and Clinical implications 
Both OT and ZM implants had favorable survival rates (97.75 vs 98.5%, respectively). Although OT performed slightly better than ZM in the immediate loading and 1-stage surgery, there were not many statistically significant differences between the two implant types when comparing most of the indices.

Two-types of Hydroxyapatite Coating Implant - A Retrospective Clinical Study