Histomorphometric study of bone reactions with different hydroxyapatite coating thickness on dental implants in dogs

The purpose of this study was to evaluate the effects of different hydroxyapatite (HA) coating thicknesses on osseointegration after dental implantation in dogs. Six dogs, weighing 10–15 kg, were used in this study. The fixtures, with HA coatings of different thicknesses and made by Dentis, were implanted for 12 weeks in right iliac crestal bone sites and for 6 weeks in left iliac crestal bone sites. Implants in the control group were coated with resorbable blast medium, whereas those in the experimental group were coated with HA of different thicknesses (1, 5, and 15 μm). All dogs were sacrificed at 12 weeks after implant placement, and histological and histomorphometric analyses were performed. The implants were all successful, and a significant difference between the control and experiment groups was observed at 6 weeks, although no significant difference between the control and experimental groups was seen at 12 weeks. These results suggested that HA implant coating may positively affect early osseointegration, but coating thickness had no significant effect on ultimate osseointegration.