An histologic and histomorphometric study of bone reactions to unloaded and loaded non-submerged single implants in monkeys: a pilot study.

The authors present an histologic study of bone peri-implant tissue responses to non-submerged unloaded and early-loaded titanium screw implants in monkeys. Titanium screws were placed in the maxillae of 3 Macacus rhesus monkeys. One crown for each of three implants was placed after 30 days under occlusal contact, while the other three implants were left unloaded (one pair per animal). Fifteen months later, the animals were killed, and block sections were obtained to be processed for histology. Thin ground sections were excised so that histomorphometric analyses could be performed. In all samples examined, a tight contact of new bone to the implant surfaces was observed. Moreover, around the implant necks of the early-loaded screws was observed an histologic pattern of lamellar, cortical bone, thicker than in unloaded implants. Comparison with peri-implant bone of adjacent teeth showed a similarity to the surfaces of loaded peri-implant bone.