Apical Flap Repositioning vs. Mucosa Excision With Free Gingival Grafts for Peri-Implant Keratinized Mucosa Augmentation

Overview

The goal of this clinical trial is to learn which surgical technique works better to increase the amount of firm gum tissue (called keratinized mucosa) around dental implants in adults. The main question it aims to answer is: -Does repositioning the gum flap upward with stitches lead to a greater gain in firm gum tissue width at 6 months compared to simply removing the extra gum tissue, when both techniques are combined with a free gum graft? Researchers will compare two techniques used during the second stage of implant surgery to see which one produces a greater gain in firm gum tissue around the implant. Participants will: * Receive a free gum graft (a small piece of tissue taken from the roof of the mouth) placed around their dental implant during a routine surgical visit * Be randomly assigned to one of the two surgical techniques * Have digital scans of their mouth taken at 5 timepoints over 6 months * Complete a pain diary and answer questions about their experience during the first week after surgery * Attend follow-up visits at 6 weeks, 3 months, and 6 months after surgery

This superiority multicenter randomized clinical trial is coordinated by the Universitat de Barcelona (UB) and includes the Universidad Complutense de Madrid (UCM) as a collaborating center. Participant selection Adults with osseointegrated implants in the posterior maxilla or mandible presenting keratinized mucosa width of 2 mm or less and/or vestibular depth less than 4 mm will be screened for eligibility. Participants must be in periodontal and peri-implant health and have a plaque index of 15% or less. Randomization Eligible participants will be randomly assigned (1:1) to one of two treatment groups using an Interactive Web Response System (IWRS) provided by Sealed Envelope Ltd. Randomization will take place intraoperatively, once the partial-thickness mucosal flap has been prepared. Interventions Group 1 (Control): Free gingival graft with apical repositioning and suturing of the vestibular mucosal flap to the periosteum Group 2 (Experimental): Free gingival graft with excision of the vestibular mucous tissue Outcome assessment Soft tissue changes will be assessed at 5 timepoints (T0, Tim, T6w, T3m, T6m) using intraoral scans (TRIOS 3®, 3Shape) analyzed with Geomagic Control X® software through three-dimensional digital superimposition. Clinical measurements will also be performed using a calibrated periodontal probe and a customized thermoplastic stent to standardize the measurement point across visits. Participants will complete a pain diary during the first 7 postoperative days recording pain intensity (100 mm visual analogue scale), analgesic consumption, and days with limited activity. Sample size A total of 46 participants (23 per group) are required, accounting for a minimum clinically relevant difference of 1 mm in KTW gain, a standard deviation of 1.3 mm, 80% statistical power, 5% significance level, an intraclass correlation coefficient of 0.30 for multiple implants per patient, and a 15% dropout rate. Statistical analysis The primary outcome will be analyzed in the intention-to-treat population using a generalized linear mixed model (GLMM), with patient as a random effect, adjusted for baseline KTW and study center.