Immediate Implant Placement in the Posterior Region Combining Sealing Socket Abutment and Peri-implant Socket Filling.A Randomized Controlled Clinical Trial

Study population

Hopeless maxillary or mandibular molars with tooth anatomy and bone anchorage allowing an immediate implant procedure: apical bone height of at least 5 mm or presence of interradicular septum, socket with intact bone walls, absence a large apical periodontitis, Patients needing tooth replacement in the posterior region (molars) will be recruited from the Department of Periodontology and Oral and Implant Surgery of the University of Liège, Belgium. All the patients will meet the following inclusion criteria: good general health (ASA I/II), more than 18 years old, smoker < 10c/day, one hopeless tooth, healthy periodontal condition, the presence of at least 2 mm of keratinized gingiva, intact buccal bone wall, adequate plaque control (FMPS ≤ 25%), adequate bone quantity allowing an immediate implant procedure (apical bone height of at least 5 mm or presence of interradicular septum) and finally written consent provided. The exclusion criteria will be: auto-immune disease or immunocompromised patients, uncontrolled diabetes, use of steroids or biphosphonates, local or systemic infection (medical treatment needed prior to entrance to the study), pregnancy or breastfeeding, alcoholism or chronically drug abuse. The local exclusion criteria will be: bone availability requiring an angulated abutment, untreated local inflammation, cyst, mucosal disease or oral lesions, local irradiation therapy, oral communication with sinus after the extraction. All the patients will have to read and sign the informed consent form prior to the surgery.

Procedures

After a local anesthesia, in both groups, experienced surgeons will proceed to minimally invasive tooth extraction of the hopeless tooth. The consecutive drills for implant placement will be carried out according to the recommendation of the manufacturer while considering the future position of the crown for a screw-retained restoration and the socket anatomy. Then, implants (TLX, SLA active, Straumann Group, Basel, Switzerland) will be placed immediately in a flapless manner and an insertion torque of at least 20Ncm will be required to continue the procedure. The remaining socket will be filled with a Deproteinized Bovine Bone Mineral DBBM (Straumann Xenograft, Straumann Group, Basel, Switzerland). Once the implant placed and the socket procedure completed the patients will be allocated either to the control group or the test group. In control group, a conventional healing abutment will be placed and the remaining gap of the socket will be closed with collagen matrix (Collacone, Straumann Group, Basel, Switzerland). In the test group, an SSA will be made immediately in a chair-side manner. A Variobase (Straumann Group, Basel, Switzerland) will be placed at the implant and Teflon will be used to protect the biomaterial and implant neck. Flowable composite will be used to start shaping the form of the future SSA. On the chair-side, the finalization of the emergence profile in a tulip concave shape by additive technique will take place. Before insertion, the SSA will be polished, cleaned and disinfected in a series of ultrasonic baths (Soapy water, water and alcohol). The insertion will be made at 15 N/cm and the access hole will be obturated with teflon and Telio (Ivoclar vivadent, Schaan, Liechtenstein). A standardized parallel peri-apical radiograph using a custom-made film holder will be taken in order to record the baseline bone level. Each patient will be instructed to rinse twice daily with an aqueous solution of 0,2% Chlorhexidine (Corsodyl®, GSK, Brentford, United Kingdom) and to avoid brushing of the area until the first recall 10-12 days later. Antibiotic will be prescribed (Amoxicillin® 500mg 3x/d during 5 days) and anti-inflammatories (Ibuprofen® 600 mg) as well as additional analgesics (Paracetamol® 500 mg) will recommended according to the patient's needs. Three months after implantation, in both groups, the abutments will be removed, the osseointegration of the implants will be checked and a CAD-CAM Zirconia monolithic crown will be placed. The transmucosal design from the SSA will replicated on the final crown and in the control group the design of the crown will be determined according to the soft tissue profile.

Follow-up evaluations and data recording will be performed 7-10 days, 3 months, 6 months and 12 months after the surgery.