Timing of Soft Tissue Grafting Following Immediate Implant Placement

Patients undergoing single immediate implant placement (IIP) in the premaxilla will be invited to participate in this randomized controlled trial (RCT). Prior to surgery, a small- field low-dose cone beam computed tomography (CBCT) is taken to verify the integrity of the facial bone wall and an adequate amount of apical and palatal bone availability for implant anchorage. In all of the patients, a connective tissue graft (CTG) will be harvested and inserted into the buccal mucosa to increase soft tissue thickness around the immediately installed implant. However, included patients will be randomly allocated to either receive the CTG immediately after implant installation (Immediate soft tissue grafting, ISG = control group) or 3 months after implant installation (Delayed soft tissue grafting, DSG = test group). Forty sealed envelopes are prepared for that purpose, of which 20 are internally labeled as "DSG" and 20 as "ISG". Following IIP, a sealed envelope will be opened to reveal the treatment concept In both groups, a cutting implant is installed in an optimal 3D position. Socket grafting is performed with deproteinized bovine bone mineral to limit buccal bone resorption and to optimize soft tissue stability. In the ISG group, a pouch is made in the buccal mucosa using microsurgical instruments. Thereupon, a free gingival graft is harvested from the palatal mucosa in the premolar area and de-epithelialized to arrive at a CTG of about 1 mm thickness. Height and length are tailored to the dimensions of the site. Then, the CTG is brought into the pouch and fixed with two single sutures onto the buccal mucosa. Finally, a healing abutment is installed, which is replaced by a provisional implant crown 2 days later. In the DSG group, implant placement, socket grafting and installation of a provisional implant crown occur as described above. In contrast, a buccal pouch is performed 3 months after implant installation. Graft harvesting, adaptation and fixation are perf