IntroductionTo evaluate the adjunctive effect of glycine‐powder air‐polishing (GPAP) to full‐mouth ultrasonic debridement (Fm‐UD) in the treatment of peri‐implant mucositis, and to determine the impact of implant and patient‐level variables for disease resolution.MethodsIndividuals with a diagnosis of peri‐implant mucositis were consecutively included in this randomized parallel arm clinical study. All the participants received a session of Fm‐UD. Only implants allocated to the test group were additionally treated with GPAP. Clinical assessments were recorded at baseline, at 3 and at 12 months following intervention. The primary outcomes were complete disease resolution (DR1), defined as absence of bleeding sites at probing per implants, and partial disease resolution (DR2), measured as the presence of less than two bleeding sites at probing per implant. A final logistic multivariate regression model was built to evaluate the predictive role of implant and patient‐level variables on DR.ResultsFifty two patients and 157 implants were included. Both groups displayed significant reduction in the extent of bleeding on probing and plaque levels. At 12 months, DR1 was achieved in 16% and 27% of participants for the test and the control group respectively. IDR1 was best predicted by the number of bleeding sites (OR = 2.7, p = 0.04) and the greatest PPD value (OR = 2.7, p = 0.05), while IDR2 by the prosthetic connection (OR = 2.59, p = 0.02), the mean PPD (OR = 2.23, p = 0.04), the FMBS (OR = 4.09, p = 0.04), and number of implants (OR = 4.59, p = 0.02).ConclusionsDespite significant improvements of clinical signs of peri‐implant inflammation, the use of GPAP appears to have no adjunctive effect as compared with Fm‐UD alone in the achievement of DR. Elevated initial levels of bleeding and PD predicted inferior likelihood of reaching disease resolution. The present randomized parallel arm clinical study was registered on Clinicaltrials.gov and received the following registration number: NCT05801315. This clinical trial was not registered prior to participant recruitment and randomization (https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0009965&selectaction=Edit&uid=U0004FXM&ts=2&cx=fje7l8).