The study was designed as a double-blinded, single-center, randomized clinical trial. Three different types of collagen membranes, ribose cross-linked (RCL) OSSIX Agile, glutaraldehyde cross-linked (GCL) - BioMend Extend, and non-cross-linked (NCL) Jason MB GmbH, were selected for the study.
During the first visit, digital intraoral impressions and clinical pictures will be taken, periodontal charts filled, and oral hygiene sessions conducted by trained hygienists. Two weeks later, during the second visit, patients will be reexamined to exclude any signs of inflammation. Membranes will be cut to a uniform size of 8\*10 mm by an assistant prior to placement. They will be placed in a randomized mesiodistal order on the buccal mucosa, apical to the gingival margins of maxillary premolar and molar teeth (the future position will be evaluated on the intraoral scanned model). To fix the membranes, a vestibular sling suture without any perforation (PTFE 3/0) will be used. A light-cured periodontal dressing (Barricaid, Dentsply Caulk, Dentsply Int. Inc., York, PA, USA) will be placed on the buccal site to fix a knot and two other points on the membrane to fix it to the suture. Standard intraoral pictures will be taken. Patients will be instructed to avoid hard foods, brushing in the area of the membrane, and excessive movements to prevent dislocation of the structure. The same oral hygiene products will be provided to all patients.
Follow-up visits will be scheduled at 3, 7 and 10 days. At the 10-day follow-up clinical evaluation will be performed to assess any perforation. A set of pictures will be taken. Membranes integrity will be analyzed by two blinded examiners using a Scale.
