Implant Abutment Cleaning by Plasma of Argon: 5-Year Follow-Up of a Randomized Controlled Trial

Background: Contamination of implant abutments could potentially influence the peri-implant tissue inflammatory response. The aim of the present study is to assess the radiographic bone changes around customized, platform-switched abutments placed according to the one-abutment-one-time'' protocol, with and without plasma of argon cleaning treatment. Methods: Thirty healthy patients with thin gingival biotype (< 1 mm) and history of periodontal disease received one maxillary implant each. Immediately before abutment connection, patients were randomly assigned to control group (cleaning protocol by steaming) or test group (plasma of argon treatment). Outcome measures were: 1) success rate of implants and prostheses; 2) biologic and prosthetic complications; 3) peri-implant marginal bone loss (MBL); 4) esthetic and periodontal parameters; and 5) patient satisfaction. Results: Neither implants nor prostheses were lost in either group at the 5-year follow-up examination. Overall, both groups showed a slight amount of peri-implant bone loss from baseline to 5 years. A statistically higher mean MBL was found in the control group compared with the test group at 6, 24, and 60 months after crown connection. Nevertheless, during the entire follow-up period, intragroup comparison demonstrated statistically significant mean MBL in the control group, but not in the test group. The test group showed a higher mean gain at the soft tissue margin, but not for the papilla. All implants showed good periodontal parameters, with no significant differences between groups. Conclusion: Plasma of argon could be used to disinfect implant abutments before insertion to minimize future peri-implant bone resorption.