Histomorphometric Analysis of Bone Regeneration Using a Dual Layer of Membranes (dPTFE Placed Over Collagen) in Fresh Extraction Sites: A Canine Model
In untreated extraction sockets, buccal bone remodeling compromises the alveolar ridge width. The aim of this study was to histologically assess the efficacy of using a dual layer of membranes (high-density polytetrafluoroethylene [dPTFE] placed over collagen) for ridge preservation in fresh extraction sites. Eight beagle dogs were used. After endodontic treatment of mandibular bilateral second (P2), third (P3), and fourth (P4) premolars, mandibular bilateral first premolars and distal roots of P2, P3, and P4 were extracted atraumatically. Animals were randomly divided into 4 treatment groups. group 1, the control group, received no treatment; in group 2, allograft was placed in the alveolum and the socket covered with dPTFE membrane; in group 3, allograft was placed in the alveolum, the buccal plate was overbuilt with allograft, and the socket was covered with dPTFE membrane; in group 4, allograft was placed in the alveolum and covered with dual layer of membranes (dPTFE placed over collagen). No intent of primary closure was performed for all groups. After 16 weeks, the animals were sacrificed and mandibular blocks were assessed histologically for buccolingual width of alveolar ridge, percentage of bone formation and bone marrow spaces, and the remaining bone particles. The buccolingual width of the alveolar ridge was significantly higher among sockets in group 4 than in group 1 (P < .05). the amount of newly formed bone in each socket was higher in extraction sockets in group 4 than in groups 1, 2, and 3 (P < .001). A significant difference was found in the percentage of bone marrow spaces among all groups (P < .001). No significant difference was found in the number of nonresorbed bone particles among the groups. Using a dual layer of membrane was more effective in ridge preservation than conventional socket augmentation protocols.
Clinical and radiographic pictures of the treatment protocol. (a) Preoperative clinical photograph. (b) The distal roots were hemisectioned and extracted with no dehiscence. (c) A measuring surgical stent was fabricated to ensure repeat measurements over time. (d) The different sites with application of membrane alone, membrane and bone graft, dual-layer membrane, and bone graft material. (e) Primary closure was achieved. (f) Radiograph showing endodontically treated distal roots filled with gutta percha.
Histologic evaluation of extraction sockets in group 1 (no treatment group) using toluidine blue acid fuchsin. (a) Mandibular cortical bone surrounded by oral mucosa in the area of the first premolar tooth. The apex of the canine root surrounded by periodontal ligament can also be seen at 10× magnification. (b) At ×40 magnification, mature compact bone with osteons tissue can be seen (arrow) as well as fibrous connective tissue of the oral mucosa (arrow head).
Histologic evaluation of extraction sockets in group 2 (particulate graft placed in alveolum and socket covered with a high-density polytetrafluoroethylene membrane) using toluidine blue acid fuchsin. (a) At ×10 magnification, cortical bone with mature compact bone can be seen. Inside the section, trabecular bone can also be observed. (b) At ×40 magnification, cortical, compact, mature bone belonging to the external portion of the jaw (arrow). At ×40 magnification, particulate graft surrounded by connective tissue are located outside the defect (arrow head). (c) At ×100 magnification, newly formed bone with small bone marrow spaces and cement lines can be observed between preexisting bone and newly formed bone (arrow). At ×100 magnification, connective tissue is seen in close proximity to newly formed bone (arrow head). (d) At ×40 magnification, mature bone tissue can be observed (arrow) with no residual particles of particulate graft inside the bone defect. At ×40 magnification, newly formed bone in tight contact to preexisting bone can be observed (arrow heads).
Histologic evaluation using toluidine blue acid fuchsin of extraction sockets in group 3 (particulate graft placed in alveolum, buccal plate overbuilt with particulate graft, and socket covered with a high-density polytetrafluoroethylene membrane). (a) At ×10 magnification, cortical, compact, and mature bone can be observed with fibrointegrated residual particulate graft particles next to oral mucosa. In the central portion of the sample, trabecular bone can be observed in the central portion. (b) At ×40 magnification, a small bone marrow space can be observed inside the cortical bone (arrow) with particulate graft particles surrounded by fibrous tissue (arrow head). (c) At ×40 magnification, preexisting bone (arrow) and newly formed bone (arrow head) can be observed. (d) At ×40 magnification, cortical bone (arrow) and fibrointegrated residual particulate graft particles can be observed outside the defect (arrow head). (e) At ×100 magnification, fibrointegrated particulate graft particles (arrow head) can be observed with dense connective tissue in tight contact with particulate graft. (f) At ×100 magnification, dense connective tissue (arrow) and particulate graft particles (arrow head) can be seen.
Histologic evaluation using toluidine blue acid fuchsin of extraction sockets in group 4n (particulate graft placed in alveolum and covered with a dual layer of membrane [high-density polytetrafluoroethylene membrane placed over a collagen membrane]). (a) At ×10 magnification, Trabecular bone can be observed in the area where defect was induced. (b) At ×10 magnification, bone trabeculae in the medullary portion of the section can be observed. (c) At ×100 magnification, particulate graft particles surrounded by connective tissue can be seen. (d) At ×40 magnification, newly formed bone in tight contact to preexisting bone (arrow) with fibrointegrated particulate graft can be observed (arrow Head). (e) At ×40 magnification, mature bone with areas of remodeling can be observed (arrow) with fibrointegrated particulate graft particles inside the defect (arrow head). (f) Bonding between the newly formed bone and native bone.
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