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.
Adults aged 20 years or older.
Partially edentulous patients requiring a single dental implant in the posterior mandible.
Thin peri-implant soft tissue phenotype (<2 mm).
Horizontal alveolar ridge width of at least 6 mm.
Local pathological lesions affecting the surgical site.
Smoking.
Pregnancy or breastfeeding.
Alcohol abuse or parafunctional habits that may compromise implant survival or wound healing.
Parallel
subepithelial connective tissue graft
Procedure/SurgeryHarvesting of an autogenous connective tissue graft from the palate and placement over an equicrestally positioned dental implant to augment peri-implant soft tissue thickness.
Submerged Tenting Abutment
DevicePlacement of a submerged low-profile tenting healing abutment over an equicrestally positioned dental implant to support peri-implant soft tissue during healing.
Sub-crestal Implant Placement
Procedure/SurgeryPlacement of a dental implant approximately 2 mm apical to the alveolar crest without soft tissue grafting or tenting abutment placement.
Change in Peri-implant Soft Tissue Thickness
Change in peri-implant soft tissue thickness from baseline measured using three-dimensional digital intraoral scanning (Medit Intraoral Scanner) and digital volumetric analysis (Medit Design software). Measurements will be performed by blinded outcome assessors and expressed in millimeters (mm).
Histological Characteristics of Peri-implant Soft Tissue
Histological evaluation of peri-implant soft tissue biopsy specimens obtained during second-stage implant surgery. Tissue sections will be stained with hematoxylin and eosin and Masson's trichrome to assess epithelial thickness and collagen density.
Clinical Peri-implant Soft Tissue Thickness
Clinical measurement of peri-implant soft tissue thickness using standardized transgingival probing.
Postoperative Pain
Participant-reported postoperative pain measured using a 10-point Visual Analog Scale (VAS). The scale ranges from 0 to 10, where 0 = no pain, 1-3 = mild pain, 4-6 = moderate pain, 7-9 = severe pain, and 10 = worst pain imaginable (very severe pain). Higher scores indicate greater postoperative pain.
Peri-implant Crestal Bone Level Changes
Changes in peri-implant crestal bone level assessed using standardized periapical radiographs analyzed with ImageJ software.
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