Surgical Treatment of Peri‐Implantitis Combined With Keratinized Mucosa Augmentation: Results of a Dual‐Center 3‐Year RCT

AimTo evaluate the medium‐term efficacy of using a xenogeneic collagen matrix to augment the width of the peri‐implant keratinized mucosa (PIKM) as an adjunct to the surgical treatment of peri‐implantitis.Material and MethodsIn this 36‐month parallel‐arm randomized controlled clinical trial, patients with peri‐implantitis were randomly assigned to a combined protocol of resective peri‐implantitis surgery and a PIKM augmentation procedure, either with an autologous free gingival graft (FGG) or a collagen matrix (CM). Primary outcomes were the increase in the width of PIKM and probing pocket depth (PPD) reduction at 36 months. As secondary outcomes, radiographic and patient‐reported outcomes were assessed.ResultsForty‐one patients (20 in the CM group and 21 in the FGG group) completed the three‐year follow‐up. PIKM increased in both groups, but the increase was significantly higher in the APF (apically positioned flap) + FGG group compared to the APF + CM group [2.0 (95% CI: 1.3, 2.7) mm in the FGG group compared to 1.0 (95% CI: 0.5, 1.5) mm in the CM group; p = 0.048]. PPDs were reduced by 1.5 mm (95% CI: 1.1, 1.9) and 1.4 mm (95% CI: 0.6, 2.2), respectively. Disease resolution (maximum one site with bleeding on probing, no suppuration, no further bone loss > 0.5 mm, and PD ≤ 5 mm) was 47.6% in the FGG group and 35.0% in the CM group.ConclusionTested surgical modalities resulted in similar improvements in the clinical parameters. Both FGG and CM increased the PIKM, but PIKM was greater at the 36‐month examination in the FGG group.