Comparisons of the Effects of Secondary Healing, Primary Healing and Collagen-Membrane-Based Primary Healing on Bone Level and Periodontal Status After Partially Impacted Mandibular Third Molar Surgery

The study included patients with no history of medical illness or medication that could influence the course of postoperative wound healing and patients with vertical or mesioangular partially impacted third molar teeth (3M) with healthy periodontium. Patients were excluded from randomisation if they had acute pericoronitis, a preexisting abscess or cellulitis, any restorations or carious lesions on the distal surfaces of the adjecent second molar teeth (2M), or pathological conditions associated with the third molar. Oral contraceptive users and smokers were also excluded. Patients were randomly assigned to three groups: the SC (secondary closure) group, involving partial closure of the extraction site to allow secondary healing; the PC (primary closure) group, involving total closure of the extraction site by sliding the flap to allow primary healing; and the MBPC (membrane-based primary closure) group, involving total closure of the extraction site by sliding the flap and using a collagen membrane. The examination and clinical selection of the patients was carried out by a single researcher who performed the surgical procedure. Patients were randomised by the envelope method. Postoperative measurements were performed by a third-party blinded researcher who had no information about the patients or their study groups. Surgical operations were carried out by a single surgeon with each patient under local anesthesia, which was achieved with up to 4 mL of articaine and a 1:100,000 ratio of epinephrine (Ultracaine D-S Forte, Aventis). An incision was made from the anterior border of the mandibular ramus, extending to the distal surface and the buccal gingivodental sulcus of the 2M. The incision was continuous, with a vertical incision, oblique into the mandibular vestibular fornix, aligned with the mesiobuccal cusp of the 2M. A full-thickness mucoperiosteal triangular flap was elevated. If necessary, osteotomy was performed with a bur, and tooth sectioning was performed when necessary under constant irrigation with sterile isotonic saline. After extraction, curettage and elimination of the remaining dental follicle were performed. In all cases, wound closure was carried out with atraumatic silk sutures. In the MBPC group, a resorbable collagen membrane (Evolution®, Osteobiol-Tecnoss, Italy) was positioned to extend 3–4 mm beyond the margin of the bone defect, and the area was closed in the same way as a primary closure. The patients were given standard postoperative instructions. Patients were administered antibiotics (amoxicillin + clavulanic acid), nonsteroidal anti-inflammatory drugs (dexketoprofen trometamol) and mouthwash (with 0.12% chlorhexidine). The sutures were removed after 7 days. Digital panoramic radiographs were obtained preoperatively and three months postoperatively. Cemento-enamel junction (CEJs) was used as reference points, and the distances between the CEJ and the alveolar bone crest on the distal aspect of the adjacent 2M were measured as millimeter using calibrated radiograph measurement software (MedData Medical Software, Ankara, Turkey). All radiological measurements were performed twice and independently, and mean values were recorded preoperatively (T1) and three months postoperatively (T2). The differences (positive or negative) between the pre- and postoperative radiographic measurements constituted one of the primary outcomes of this study. Another primary outcome variable was the periodontal status of the 2Ms. Periodontal measurements were performed preoperatively (T1) and three months postoperatively (T2). The pocket depths and plaque index scores of the distobuccal (DB), distolingual (DL), midbuccal (MidB) and midlingual (MidL) surfaces of the 2Ms were recorded. All periodontal pocket depth (PPD) measurements were performed as millimeter using William’s periodontal probe (Aesculap AG & Co., Tuttlingen, Germany). To assess the periodontal plaque index (PPI) scores, the Silness & Löe plaque index was registered on the distal aspects of the 2Ms, and the mean values were used.