Re-use of implant coverscrews changes their surface properties but not clinical outcome

This study examined the effect of re-using coverscrews for dental implants (Branemark) and the influence of re-use on clinical outcome. Nine patients, each receiving 3 implants in either the maxilla or the mandible, received 1 new coverscrew, 1 re-used coverscrew, and a third coverscrew that had bee n used multiple times. In all cases, the re-used coverscrews had been washe d, mechanically cleaned, and steam-sterilized prior to re-implantation. Cli nical outcome was assessed by X-ray analysis of the mandible/ maxilla and l ight microscopy of histologically prepared sections of the overlying tissue . The surfaces of the coverscrews were characterized by profilometry, scann ing electron microscopy (SEM), Auger electron spectroscopy (AES), and atomi c force microscopy (AFM). There was no difference in clinical outcome wheth er the coverscrews were new or re-used multiple times. Histological evaluat ion showed no influence of re-use on the overlying epithelial and connectiv e tissues at the time the coverscrew was removed. Surface topography and ro ughness changed with increasing number of uses, but surface chemistry was v irtually unchanged. SEM and AFM analyses revealed the presence of machining marks, as well as deep scratches, across the surface of the re-used covers crews. This study shows that coverscrews can be cleaned and re-used without any apparent adverse affect on clinical outcome. However, the cleaning pro cedures, as well as the surgical procedure, change the surface characterist ics. If this approach were applied to the implant itself, it might affect o sseointegration.