Peri-implant soft tissue thickness is an important determinant of the long-term stability and success of dental implants. Patients with a thin peri-implant soft tissue phenotype are at increased risk of soft tissue recession, marginal bone loss, and compromised esthetic and functional outcomes. Subepithelial connective tissue graft (SCTG) is considered the gold standard for soft tissue augmentation; however, it requires harvesting tissue from the palate, increasing surgical complexity, operative time, and postoperative morbidity. Less invasive approaches, including submerged tenting abutments and subcrestal implant placement, have been proposed as alternatives to improve peri-implant soft tissue dimensions while reducing patient morbidity, but direct comparative clinical evidence remains limited.

This investigator-initiated, single-center, randomized, parallel-group clinical trial will compare three approaches for peri-implant soft tissue augmentation in patients with a thin peri-implant soft tissue phenotype requiring a single dental implant in the posterior mandible. Eligible implant sites will be randomly assigned in a 1:1:1 allocation ratio to receive either subepithelial connective tissue grafting, submerged tenting abutment placement, or subcrestal implant placement during implant surgery.

The primary objective is to compare changes in peri-implant soft tissue thickness using three-dimensional digital intraoral scanning over a 12-month follow-up period. Secondary objectives include evaluation of keratinized tissue width, clinical soft tissue thickness, histological characteristics of peri-implant soft tissue, peri-implant crestal bone level changes, postoperative pain, operative time, patient-reported satisfaction, and postoperative complications. The results of this study are expected to provide evidence regarding whether minimally invasive treatment approaches can achieve clinical outcomes comparable to connective tissue grafting while reducing surgical morbidity and improving patient-centered outcomes.