A multi-center study comparing dual acid-etched and machined-surfaced implants in various bone qualities

Background: A major reason for the success of modern dental implant systems has been the development of implant designs that enhance direct bone-implant interface. Surface roughness has been a factor in this success and different systems have utilized very different implant surface roughness. The major purpose of this study was to evaluate 2 similar implants with different surface roughness characteristics. Methods: Two similarly designed, screw-type, commercially pure titanium implants, one dual acid-etched (DAE) and the other machined-surfaced (MS), were compared in this prospective, randomized-controlled, multi-center study, in which a total of 97 patients were enrolled at a private dental practice or a university dental clinic. Both implant types were placed in each patient using a 2-stage approach with a conventional 4- to 6-month healing period. Implants supported fixed prostheses, hybrid prostheses, and overdentures as dictated by the individual patient's need. All of the cases were followed using clinical and radiographic examinations. Criteria of success were the absence of peri-implant radiolucency, mobility, and persistent signs or symptoms of pain or infection. Results: Of the 432 implants (247 dual acid-etched, 185 machined-surfaced), 36 implants (12 dual acid-etched and 24 machined-surfaced) have failed. The pre-loading integration success rate of the dual acid-etched implants (95.0%) was statistically higher (P <0.01) than the success rate of the machined-surfaced implants (86.7%). At 36 months, the cumulative success rates (CSR) are 95.0% for the dual acid-etched implants and 86.7% for the machined-surfaced implants. Conclusions: The difference in success rates is most likely attributed to the acid-etched surface characteristics. The greatest performance difference is observed in the conditions of poor quality or soft bone where the 3-year post-loading CSR are 96.8% (dual acid-etched) and 84.8% (machined-surfaced).