Peri-implant Tissues Changes for Different Abutment Shapes and Heights

Influence of Supracrestal Soft Tissue on Peri-implant Bone Changes for Different Abutment Shapes and Heights: A Four-Arm Randomized Clinical Trial

The goal of this randomized clinical trial is to investigate the influence of supracrestal soft tissue on abutments of different heights (2-mm vs. 3-mm) and shapes (cylindrical abutment vs. concave abutment) on changes in the marginal bone level (bone loss and bone remodeling) in healthy, partially edentulous volunteer patients undergoing implant-supported rehabilitation.

The main questions it aims to answer are:

• Is there any difference in marginal bone loss for different abutment shapes and heights?
• Do the shape and height of the abutment affect implant success?

All participants will receive bone-level dental implants placed approximately 2-mm below the bone crest, each receiving a different type of abutment and researchers will see whether the shape and height of the abutment influence the success of the implant, periodontal probing depth (PPD), and bleeding on probing (BoP) comparing four groups of patients:

1. 2-mm high abutments with cylindrical shape.
2. 2-mm high abutments with concave shape.
3. 3-mm high abutments with cylindrical shape.
4. 3-mm high abutments with concave shape.

Clinical and radiographic assessments will be performed at abutment placement, at definitive prosthesis placement, and at 1, 3, 6, and 12 months after loading to measure marginal bone loss and peri-implant parameters.

Inclusion Criteria:

• Adults aged 18 years or older.
• Posterior edentulism (premolars/molars).
• Good general and oral health, with controlled plaque and bleeding indices.
• Sufficient bone height and width for implant placement without the need for bone regeneration procedures. Patients who require indirect sinus lift procedure simultaneously with implant placement may be included in the study.
• Presence of at least 2 mm of keratinized mucosa around the dental implant.
• Stable occlusion and healthy periodontium.
• Insertion torque ≥ 35 Ncm at the time of implant placement.
• Willingness to comply with study protocol and attend scheduled follow-up visits.

Exclusion Criteria:

• Presence of medical conditions that contraindicate implant surgery, such as heavy smoking (>10 cigarettes per day), severe bruxism, pregnancy or breastfeeding, bisphosphonate therapy, and patients undergoing chemotherapy or radiotherapy in the head and/or neck area.
• Active periodontal disease or peri-implant infection.
• Uncooperative patients or patients unable to complete follow- up.
• Implant failures.