Soft Tissue Augmentation Around Dental Implants Using Connective Tissue Graft, Submerged Tenting Abutment, or Sub-crestal Implant Placement

Evaluation of Peri-implant Soft Tissue Thickness Following Augmentation Using Subepithelial Connective Tissue Graft Versus Submerged Tenting Abutment Versus Sub-crestal Implant Placement: A Randomized Controlled Clinical Trial

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.

Study Overview

• Status: Recruiting
• Conditions: Partial Edentulism; Tooth Loss; Peri-implant Soft Tissue Deficiency
• Intervention / Treatment: Procedure: subepithelial connective tissue graft; Device: Submerged Tenting Abutment; Procedure: Sub-crestal Implant Placement

Detailed Description

Peri-implant soft tissue thickness is a critical factor influencing the biological stability, function, and long-term success of dental implant therapy. A thin peri-implant soft tissue phenotype has been associated with increased marginal bone remodeling, soft tissue recession, and compromised peri-implant tissue stability. Consequently, augmentation of peri-implant soft tissues has become an important component of implant treatment planning, particularly in patients with thin soft tissue phenotypes.

Subepithelial connective tissue grafting (SCTG) is widely regarded as the reference standard for peri-implant soft tissue augmentation because of its predictable ability to increase tissue volume and improve peri-implant tissue stability. Nevertheless, harvesting autogenous connective tissue from the palate increases operative time, donor-site morbidity, postoperative discomfort, and surgical complexity. These limitations have encouraged the development of less invasive techniques capable of enhancing peri-implant soft tissue dimensions while minimizing patient morbidity.

Submerged tenting abutments have recently been introduced as a minimally invasive method for maintaining soft tissue space during submerged healing following implant placement. By supporting the overlying soft tissues throughout the healing phase, these abutments may promote increased soft tissue thickness without the need for connective tissue harvesting. Although preliminary clinical reports have shown encouraging outcomes, direct comparisons with connective tissue grafting remain limited.

Subcrestal implant placement has also been proposed as an alternative method for improving peri-implant soft tissue dimensions. Positioning the implant platform approximately 2 mm below the alveolar crest may increase the vertical dimension of peri-implant soft tissues without requiring grafting procedures or additional prosthetic components. While this technique has demonstrated favorable biological behavior in previous studies, evidence directly comparing it with connective tissue grafting and submerged tenting abutments remains scarce.

Advances in digital intraoral scanning have enabled accurate, reproducible, and non-invasive three-dimensional assessment of peri-implant soft tissue changes over time. Digital volumetric analysis provides objective measurements while reducing operator-dependent variability associated with conventional clinical measurements. Combining digital assessment with clinical, radiographic, histological, and patient-reported outcomes provides a comprehensive evaluation of treatment effectiveness.

This investigator-initiated, single-center, randomized, parallel-group interventional clinical trial will enroll 33 implant sites in medically healthy adults requiring single implant placement in the posterior mandible and presenting with a thin peri-implant soft tissue phenotype (<2 mm). Implant sites will be randomly allocated in a 1:1:1 ratio to one of three intervention groups: (1) equicrestal implant placement with subepithelial connective tissue grafting, (2) equicrestal implant placement with a submerged tenting abutment, or (3) subcrestal implant placement without grafting or tenting abutment. Randomization will be performed using a computer-generated sequence with allocation concealment through opaque sealed envelopes. Outcome assessors and the biostatistician will remain blinded throughout data collection and analysis, whereas blinding of participants and the operating surgeon is not feasible because of the nature of the surgical interventions.

The primary outcome will be the change in peri-implant soft tissue thickness measured by standardized three-dimensional intraoral scanning and digital volumetric analysis. Secondary outcomes include histological characteristics of peri-implant soft tissues, clinical soft tissue thickness, width of keratinized mucosa, peri-implant crestal bone level changes assessed using standardized radiographs, postoperative pain measured using a visual analog scale (VAS), operative time, patient satisfaction measured using the Oral Health Impact Profile-14 (OHIP-14), and postoperative complications. Participants will be followed according to the predefined study schedule for 12 months after implant placement using standardized clinical, digital, radiographic, and patient-reported assessments.

The results of this study will provide high-quality comparative evidence regarding three contemporary approaches for peri-implant soft tissue augmentation. By evaluating volumetric, clinical, histological, radiographic, and patient-centered outcomes within the same randomized clinical trial, the study aims to identify treatment strategies that maximize peri-implant soft tissue stability while minimizing surgical morbidity. The findings may contribute to evidence-based decision-making for clinicians managing patients with thin peri-implant soft tissue phenotypes and support the development of less invasive treatment protocols for implant therapy.

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Baraa M Nagy, BDS; Phone Number: +201063278917; Email: baraa2480582@miuegypt.edu.eg
• Study Contact Backup: Name: Zeinab H Abd El Rahman, PhD; Email: zainab.hafez@miuegypt.edu.eg

Study Locations

• Egypt
  • Cairo, Egypt
    • Recruiting
    • Misr International University Dental Clinic Complex
    • Contact: Baraa M Nagy, BDS; Phone Number: +201063278917; Email: baraa2480582@miuegypt.edu.eg
    • Contact: Zeinab H Abd El Rahman, PhD; Email: zainab.hafez@miuegypt.edu.eg
    • Principal Investigator: Hani E elnahass, Phd
    • Sub-Investigator: zeinab h Abd El Rahman, Phd
    • Sub-Investigator: Baraa m Nagy, BDS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 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.
• Vertical bone height of at least 10-12 mm, confirmed radiographically.
• Adequate interarch restorative space for implant-supported restoration.
• Medically healthy (American Society of Anesthesiologists [ASA] Physical Status I or II).
• Good oral hygiene.
• Able and willing to provide written informed consent.

Exclusion Criteria:

• Local pathological lesions affecting the surgical site.
• Smoking.
• Pregnancy or breastfeeding.
• Alcohol abuse or parafunctional habits that may compromise implant survival or wound healing.
• Medical or local conditions that could interfere with osseointegration, soft tissue healing, or study participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Subepithelial Connective Tissue Graft (SCTG); Participants assigned to this arm will receive equi-crestal dental implant placement followed by augmentation of the peri-implant soft tissue using an autogenous subepithelial connective tissue graft harvested from the palate. The graft will be positioned over the implant site to increase peri-implant soft tissue thickness before primary flap closure.	Procedure: subepithelial connective tissue graft; Harvesting of an autogenous connective tissue graft from the palate and placement over an equicrestally positioned dental implant to augment peri-implant soft tissue thickness.; Other Names: SCTG
Experimental: Submerged Tenting Abutment; Participants assigned to this arm will receive equicrestal dental implant placement followed by placement of a submerged low-profile tenting healing abutment beneath the flap to support peri-implant soft tissue contour during healing without connective tissue grafting.	Device: Submerged Tenting Abutment; Placement of a submerged low-profile tenting healing abutment over an equicrestally positioned dental implant to support peri-implant soft tissue during healing.
Experimental: Subcrestal Implant Placement; Participants assigned to this arm will receive dental implant placement approximately 2 mm below the alveolar crest without connective tissue grafting or placement of a submerged tenting abutment.	Procedure: Sub-crestal Implant Placement; Placement of a dental implant approximately 2 mm apical to the alveolar crest without soft tissue grafting or tenting abutment placement.; Other Names: Subcrestal Implant Placement

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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).	Baseline, 3 months, 6 months, and 12 months after implant placement.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	3 months
Clinical Peri-implant Soft Tissue Thickness	Clinical measurement of peri-implant soft tissue thickness using standardized transgingival probing.	Baseline, 3 months, 6 months, and 12 months
Postoperative Pain	Participant-reported postoperative pain measured using a 10-point Visual Analog Scale (VAS).	Daily during the first 10 postoperative days
Peri-implant Crestal Bone Level Changes	Changes in peri-implant crestal bone level assessed using standardized periapical radiographs analyzed with ImageJ software.	Baseline, 3 months, 6 months, and 12 months
Width of Keratinized Tissue	Clinical measurement of peri-implant keratinized tissue width using a standardized periodontal probe.	Baseline, 3 months, 6 months, and 12 months

Collaborators and Investigators

• Sponsor: Misr International University
• Investigators: Study Chair: Hani E elnahass, Phd, Professor, Department of Oral Medicine and Periodontology, Faculty of Dentistry, Cairo University; Study Director: Zeinab E Abd El Rahman, Phd, Lecturer, Department of Oral Medicine, Faculty of Oral and Dental Medicine, Misr International University.

Publications and helpful links

General Publications

• Thoma DS, Zeltner M, Hilbe M, Hammerle CH, Husler J, Jung RE. Randomized controlled clinical study evaluating effectiveness and safety of a volume-stable collagen matrix compared to autogenous connective tissue grafts for soft tissue augmentation at implant sites. J Clin Periodontol. 2016 Oct;43(10):874-85. doi: 10.1111/jcpe.12588. Epub 2016 Aug 12.
• Thoma DS, Gasser TJW, Hammerle CHF, Strauss FJ, Jung RE. Soft tissue augmentation with a volume-stable collagen matrix or an autogenous connective tissue graft at implant sites: Five-year results of a randomized controlled trial post implant loading. J Periodontol. 2023 Feb;94(2):230-243. doi: 10.1002/JPER.22-0226. Epub 2022 Oct 28.
• Lee CT, Tran D, Tsukiboshi Y, Min S, Kim SK, Ayilavarapu S, Weltman R. Clinical efficacy of soft-tissue augmentation on tissue preservation at immediate implant sites: A randomized controlled trial. J Clin Periodontol. 2023 Jul;50(7):1010-1020. doi: 10.1111/jcpe.13816. Epub 2023 Apr 13.

Study record dates

Study Major Dates

• Study Start (Estimated): July 17, 2026
• Primary Completion (Estimated): July 15, 2027
• Study Completion (Estimated): December 15, 2027

Study Registration Dates

• First Submitted: July 15, 2026
• First Submitted That Met QC Criteria: July 15, 2026
• First Posted (Actual): July 20, 2026

Study Record Updates

• Last Update Posted (Actual): July 20, 2026
• Last Update Submitted That Met QC Criteria: July 15, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Randomized Controlled Trial; Dental Implant; Subepithelial Connective Tissue Graft; Soft Tissue Augmentation; Subcrestal Implant Placement; Posterior Mandible; Peri-implant Soft Tissue; Tenting Healing Abutment; Digital Volumetric Analysis; Submerged Tenting Abutment; Thin Peri-implant Phenotype; SCTG; Digital Intraoral Scanner
• Additional Relevant MeSH Terms: Periodontal Diseases; Mouth Diseases; Stomatognathic Diseases; Tooth Diseases; Tooth Loss
• Other Study ID Numbers: PER3253019 (Other Identifier: Misr International University); MIU-IRB-2526-025 (Other Identifier: Misr International University Institutional Review Board)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: At the time of registration, a decision regarding sharing de-identified individual participant data has not yet been finalized. Any future data sharing will be considered in accordance with institutional policies, participant informed consent, applicable regulations, and journal requirements.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No