Response of Hard and Soft Tissue Around the Dental Implant to 2-Piece Abutment Vs Conventional Restorative Protocols

An in-vivo clinical assessment and radiologic study protocol was developed and approved by the ethics committee of the Yenepoya University in Mangalore, in accordance with the Declaration of Helsinki. All patients provided written informed consent prior to the performance of any study procedures, and only data collected after the patients had signed informed consent were considered during the study analysis. A single-center, open, randomized parallel-group trial was conducted to compare the peri-implant tissue response of the abutment base treatment (test group) to that of a conventional restorative workflow with a healing abutment (control group). Patients underwent clinical assessments for the replacement of one or more missing mandibular posterior teeth with an implant-supported crown. Pre-operative CBCT scans were taken for all the patients to assess the quality and quantity of bone at the implant recipient sites.

All the surgeries were carried out by a skilled surgeon with minimal hard and soft tissue trauma during which NobelParallel TiUnite CC Implants (Nobel Biocare AB, Göteborg, Sweden) with diameters ranging from 4.3 mm to 5 mm and lengths from 10 mm to 11.5 mm were placed in healed edentulous sites in the posterior mandible in an equicrestal position. All procedures were performed using crestal incision with a full-thickness flap raised. The implants were placed at the crest of alveolar bone; no bone mill was used during the On1 base seating. The patients received broad-spectrum antibiotics for 5 days and analgesics for 2 days. The implant placement (IP) surgery was considered the baseline and was referred to as such. The On1 base (height 1.75 mm) and the On1 healing cap (Nobel Biocare AB) were placed in the test group, while the healing abutment (Conical Connection RP ø 6 x 5 mm; Nobel Biocare AB) was placed in the control group. The soft tissue was sutured (with sutures removed after 1 week), and the site was allowed a 12-week non-submerged healing, at which point the conventional tray impression was taken. At 16 weeks, a prosthetic crown (made in the university lab) was delivered, which was designated as the definitive prosthesis delivery (DPP), The follow-up appointments took place at 1-3-6 months and 1-year post-DPP.

Inclusion criteria

• Adequate width and height of bone for the placement of appropriate size implant(s).
• Well-healed edentulous sites with a minimum of 2 mm of soft tissue thickness.
• Patients willing to participate by giving informed consent.
• Patients agreeing to attend the planned follow-up visits.

Exclusion criteria

• Medically compromised patients where surgery was contraindicated.
• Patients with poor oral hygiene and/or suffering from periodontal disease.
• Patients with insufficient quantity/quality of bone.
• Patient with edentulous sites with a lack of attached gingiva.
• Patients with edentulous sites with insufficient prosthetic space.
• Patients with a history of parafunctional occlusal habits.
• Tobacco or alcohol use or drug dependency.