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

Abstract

Aim: To 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 Methods: In 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. Results: Forty-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. Conclusion: Tested 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.