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

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

Inclusion Criteria: * Men or women aged 18 years or older who voluntarily agree to sign the informed consent form before any study-related procedure is performed. * Single or multiple edentulous spaces (≤3 units) located in the posterior maxilla or mandible, presenting osseointegrated implants in first-stage surgery with a -healing period of more than 8 weeks. * ASA classification I or II. * Periodontal and peri-implant health. * O'Leary plaque index ≤15%. * Keratinized mucosa width ≤2 mm and/or vestibular depth \ 8% or per clinical judgment), immunodeficiencies or immunosuppressive treatment, uncontrolled hematological diseases or coagulation disorders, anticoagulant or antiplatelet treatment that cannot be adjusted according to standard clinical practice, active neoplasms under treatment, severe renal or hepatic insufficiency, decompensated cardiovascular diseases, and any other medical condition that, in the investigator's judgment, could compromise participant safety or proper tissue healing. * Any contraindication to oral surgical procedures. * Periodontal and peri-implant health as defined by the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. * Patients who smoke tobacco or equivalent products, as well as former smokers with an abstinence period ≤12 months. * History of substance abuse (drugs or alcohol) or any other factor (e.g., severe psychiatric illness) that, in the investigator's opinion, could interfere with the patient's ability to cooperate and comply with the study. * Patients who have participated in a clinical trial within the last 30 days. * Pregnant or breastfeeding women.