Soft-Tissue Phenotype Modification as an Adjunct to the Treatment of Peri-Implant Mucositis-A Quasi-Randomized Clinical Trial.

Aim: This quasi-randomized clinical trial evaluated the additional benefit of soft-tissue phenotype modification via free palatal graft (FPG) as an adjunct to non-surgical therapy for peri-implant mucositis. A secondary objective was to determine whether any observed effects were mediated by improved plaque control.

Methods: Forty-three patients (55 implants) with peri-implant mucositis and keratinized tissue width (KTW) < 2 mm were enrolled. One month after oral hygiene instructions and non-surgical treatment, participants were quasi-randomly allocated to either an FPG procedure (test group, n = 22) or no additional intervention (control group, n = 21). The primary outcome was bleeding on probing (BoP) extent at 6 months (i.e., number of bleeding sites per implant). Secondary outcomes included peri-implant phenotype parameters (KTW, tissue thickness, and vestibular depth), plaque extent, and other peri-implant health measures (BoP severity, probing pocket depth [PPD], peri-implant soft-tissue dehiscence [PISTD], and treatment success). Intergroup comparisons were performed using regression analyses, and a mediation analysis assessed whether treatment effects were mediated by improved plaque control.

Results: At 6 months, FPG significantly increased KTW (mean difference [MD] = 2.36 mm; p < 0.001) and tissue thickness (MD = 0.97 mm; p < 0.001), while reducing plaque extent (MD = -1.49; p < 0.001), compared with the control group. BoP extent was significantly lower in the test group (0.75 ± 1.07) than in controls (1.83 ± 1.20) (MD = -1.06; 95% CI: -1.67 to -0.44; p = 0.001). Additionally, the test group exhibited lower BoP severity (MD = -0.50; p < 0.001) and higher treatment success (OR = 8.44; p = 0.001). No significant differences were observed in PPD and PISTD. Mediation analysis suggested that the observed benefits of FPG on peri-implant health were largely independent of improved plaque control.

Conclusion: FPG effectively modified the peri-implant soft-tissue phenotype and, as an adjunct to non-surgical therapy, provided additional benefits in managing peri-implant mucositis. The effects on peri-implant health were not attributable to improved plaque control.