Bone contact around osseointegrated implants: a histologic study of acid-etched and machined surfaces.

Current literature reports that surface acid etching can improve bone--implant contact (BIC). The aim of this study was to evaluate the differences of BIC between acid-etched (Osseotite) and machined surface implants. Six white New Zealand mature rabbits were used in the present investigation. Each rabbit received two implants, specially made with two surfaces on it (one acid-etched and one machined) into each tibia. A total of 24 implants were inserted. Two animals each were killed at 15, 30, and 60 days after implant placement. Histomorphometry of BIC was statistically evaluated. The acid-etched surfaces showed a greater bone contact percentage than the machined ones during the early phase of healing (15 days), which was not statistically significant. On the other hand, after 30 and 60 days, the differences of BIC between acid-etched and machined surfaces were statistically significant. The acid-etched surface appears to improve BIC at a later stage of healing.