by Xin Shu (China), Ke Zhao

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Objectives: Alveolar ridge preservation (ARP) is pre-implant surgery that minimises alveolar ridge resorption after extraction. It involves grafting a socket with bone or biomaterials with or without barrier membrane (BM). Many guidelines suggest applying a combination of bone graft and BM, but some systematic reviews point out that the available evidence is too weak to justify the use of BM. The aim of this study was to observe the outcomes of ARP without BM in the premolar and molar region. Methods: This study included five systematically healthy patients including (1 man; 4 women; mean age 55.4 years). Their premolars or molars were irrational to treat because of severe periodontitis or large tooth defects and periapical disease. Bone volumes were measured before surgery using cone beam CT (CBCT). All extractions were performed with flap formation to remove the inflamed tissue under local anesthesia. Sockets were rinsed and curetted with alveolar curettes, before grafting with deproteinised bovine bone (BioOss Collagen). Once the extraction socket was grafted, the preserved site was directly sutured without any application of barrier membrane. After 6–9 months of healing, bone volumes were re-evaluated by CBCT. Four measures were recorded for all preserved sites before and after treatment. Horizontal volumetric changes were measured at three levels (3mm, 5mm and 7mm below the most coronal aspect of the bone crest) and marked as level I, II, III respectively, while the vertical dimensional changes were assessed by measuring the palatal and buccal wall peaks (marked as level IV). Resorption rates were calculated by the formula: Resorption rate (%) = (length of alveolar bone before extraction – length of alveolar bone after alveolar ridge preservation/length of alveolar bone before extraction x 100. The resorption rate and reduction of alveolar ridge was recorded for each level . Results: No postoperative complication occurred at any site.The resorption rates and reduction of alveolar ridge for every patient in level I, II, III and IV were recorded. The mean resorption rate and amount of reduction were14.4% and 1.4mm for level I,10.6% and 1.2mm for level II,8.4% and 0.8mm for level III,and 4.6% and 0.6mm for level IV, with a mean healing time of 7.4 months. Compared with the average bone resorption rate (25–30% in the first 6 months) and amount of reduction (3.8mm horizontally, and 1.24mm vertically in the first 6 months) of natural healing, the efficacy of ARP without BM is still satisfactory in terms of maintaining bone volume after extraction. Adequate bone width and height were obtained after ARP. Radiolucent areas of periapical disease or periodontitis were also well regenerated with bone tissue. In the subsequent implant placement procedure, a wide buccolingual osseous table with commendable bone quality was observed after re-entry. Conclusion: ARP using bone substitute materials alone, without BM coverage, is effective for maintaining bone volume, but cannot stop bone resorption. Further well-designed clinical trials are needed to evaluate the efficacy of BM.
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