Peri-implant Soft Tissue Deficiency

This randomized controlled trial compares two techniques for peri-implant soft tissue augmentation in the mandibular molar region: an autogenous connective tissue graft (CTG) and a collagen matrix. Adult patients requiring implant treatment with insufficient peri-implant soft tissue thickness will be randomly assigned to receive either CTG or a collagen matrix at the time of implant surgery. The study aims to evaluate and compare changes in peri-implant soft tissue thickness, width of keratinized tissue, and soft tissue contour over a 9-month follow-up period, as well as the occurrence of postoperative complications. The results of this study will help determine whether a collagen matrix can provide clinical outcomes comparable to those of connective tissue grafting for peri-implant soft tissue augmentation.

Peri-implant soft-tissue defects will be treated with either a volume-stable collagen matrix (VCMX; test group) or an autogenous connective tissue graft (CTG; control group) following implant placement in patients with a single missing tooth. After a mid-crestal incision and full-thickness flap elevation, the graft material will be positioned over the crest beneath the buccal flap and stabilized, followed by tension-free primary closure. Peri-implant soft-tissue thickness, echo intensity, and vascularization will be assessed non-invasively using high-resolution intraoral ultrasonography and Power Doppler imaging. Clinical periodontal parameters and patient-reported outcomes, including pain perception (visual analog scale), swelling, fatigue, analgesic consumption, and wound healing, will be recorded. These outcomes will be evaluated at baseline and on the 1st week, 1st, 3rd, and 6th months. At the 6th month, gingival biopsy samples obtained during healing abutment placement will be evaluated histologically and immunohistochemically (CD11c, CD163, COL1, COL3, MMP-1, TIMP-1) to compare the biological integration of the two graft materials.

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.