Marginal Bone Stability Using 3 Different Flap Approaches for Alveolar Split Expansion for Dental Implants—A 1-Year Clinical Study

Abstract

Width augmentation for the alveolar process using alveolar split procedures has not been studied in a comparative study with regard to marginal bone stability. Most research in this regard has used implant osseointegration as an endpoint for the success of the bone grafting procedure. The purpose of the present clinical trial was to retrospectively evaluate the stability of the buccal crestal bone around dental implants placed into alveolar split graft sites using 3 different approaches: a minimal flap, a partial-thickness flap, and a full mucoperiosteal flap. Implants were placed simultaneously or delayed to alveolar split grafting. The aim of the present study was to do a comparative analysis of these 3 techniques by clinical detection for the presence or absence of marginal bone using a periodontal probe 1 year after implant restoration. The working hypothesis was that detachment or disturbance of the blood supply of the buccal plate would be influenced by the flap procedure used and would therefore affect the late marginal bone stability around the implants. A total of 40 consecutive patients were treated in 2 different practice locations (20 at each office) with alveolar split procedures and simultaneous implant placement, using 3 different flap approaches and were seen again after 1 year at the 2 private office locations. The patients were in general good health, without active periodontal disease. All patients were nonsmokers. Patients with diabetes mellitus were excluded from the study. The aim of the present study was to establish the stability of the mobilized buccal bone plate, which could only be observed indirectly. The method used to detect the presence or absence of buccal marginal bone was a blunt periodontal probe used in the sulcus on the facial surface of the restored implant or a sharp explorer used transgingivally to detect marginal bone presence. However, the bone thickness could not be established using either of these methods. This was done in both practice locations by the surgeon who had performed the procedure (in a few cases, open flap procedures were done up to 1 year after grafting, which permitted direct observation of the original treatment site). The 3 different flap approaches studied were full-thickness flap reflection, partial-thickness flap reflection, and minimal flap reflection of the osteoperiosteal flap approach to crestally split and then widen the alveolus. A total of 40 consecutive patients treated with 65 alveolar split expansion procedures done in 2 practice locations during a 2-year period were statistically analyzed retrospectively for buccal bone augmentation presence and implant restorability after 1 year of healing. Facial bone loss of 2 mm or more was seen in 11 sites, 10 of which were full flap reflections and 1 an osteoperiosteal flap site. Implant osseointegration was 92.5% for the osteoperiosteal flaps, 93.3% for the partial-thickness flaps, and 94.4% for the full-thickness flaps. The 3 flap approaches to alveolar widening by crest splitting with implant placement had a sustained increased alveolar width after 1 year. However, most full flap alveolar split cases had facial bone loss and gingival recession. The osteoperiosteal flaps (book flap) and partial-thickness flaps showed stable buccal bone patterns. The results of the present clinical study of relatively early osseous remodeling suggest that full mucoperiosteal flaps should not be reflected when an alveolar split is done. However, to further elucidate the marginal bone vitality, a longer study period must be undertaken to more fully validate the alveolar split procedure and verify the best flap approach.