Purpose: The influence of surface modifications on osseointegration in newly formed bone is not well established. The purpose of this study was to compare osseointegration at acid-etched versus turned implants in newly formed and native bone. Methods: Supra-alveolar peri-implant defects were created in 8 hound/Labrador mongrel dogs. Titanium implants 10 mm long (2 turned and 1 dual acid-etched) were placed 5 mm into the surgically reduced alveolar crest, creating 5-mm supra-alveolar peri-implant defects. Recombinant human bone morphogenetic protein-2 (rhBMP-2; 0.4 mg) in a collagen carrier was used to induce new bone formation. A macroporous, expanded polytetrafluoroethylene device was used to delineate new bone formation. The animals were euthanized at 8 weeks for histometric analysis of the experimental sites. Results: There were no significant differences in rhBMP-2induced bone density (mean plusmn SD) at acid-etched versus turned implants (20.6% plusmn 5.3% vs 23.8% plusmn 4.7%; P = .232). However, there was a significant difference in bone-implant contact in favor of the acid-etched implants (12.3% plusmn 6.8% vs 7.9% plusmn 3.1%; P = .05). Native bone density averaged 63.9% plusmn 7.5% and 64.5 plusmn 9.0% for acid-etched and turned implants, respectively (P = .641). Nevertheless, bone-implant contact was significantly enhanced at acid-etched versus turned implants (59.7% plusmn 11.3% vs 40.7% plusmn 21.2%; P = .005). Conclusions: Surface dual acid-etching of titanium implants has a positive effect on osseointegration in newly formed and native bone. Significant differences in bone density do not appear to influence this effect. Keywords: bone, e-PTFE, osseointegration, rhBMP-2, tissue engineering, titanium implants