Periosteal expansion osteogenesis using a tubular dynamic frame device: An experimental study in rats.

Periosteal expansion osteogenesis (PEO) is a technique for augmenting bone by creating a gradual separation between the bone and periosteum. This study assessed PEO-induced bone formation around the femurs of rats using a dynamic frame device (DFD), consisting of a shape memory membrane made of polyethylene terephthalate (PET) formed into a tubular shape. The DFDs, consisting of a PET membrane coated with hydroxyapatite (HA)/gelatin on the bone-contact surface, were inserted between the periosteum and bone of the femurs of rats. In the experimental group, DFDs were suture-fixed to the femur with 4-0 Vicryl Rapid; in the control group, 4-0 silk thread was used for fixation. Five rats per group were euthanized at intervals of 3, 5, and 8 weeks postoperatively. Bone formation was evaluated via micro-CT imaging, histomorphometry, and histological analysis. Morphological analysis revealed new bone between the femur and the periosteum, expanded by the DFD, in all groups. The mean values of new bone were 0.30 mm2 proximally, 0.18 mm2 centrally, and 0.82 mm2 distally in the control group, compared to 1.05 mm2 proximally, 0.27 mm2 centrally, and 0.84 mm2 distally in the experimental group. A significant difference in new bone was observed in the proximal region of the experimental group. Histological examination showed that a single layer of newly formed neoplastic bone was noted on the cortical bone surface across all sites. The proximal portion displayed a bone marrow cavity at the center, encircled by a thick bone cortex with a layered structure. New bone formation was notable between existing cortical bone and the periosteum, particularly at both ends of the DFD. The use of PET in PEO was a viable option for achieving ideal bone morphology.

Static and dynamic guided bone regeneration using a shape-memory polyethylene terephthalate membrane: An experimental study in rabbit mandible.

BACKGROUND: Periosteal expansion (PEO) results in the formation of new bone in the space created between existing bone by expanding the periosteum. PEO has already been performed on rabbit parietal bone and effective new bone formation has been demonstrated. In this study, the utility of a polyethylene terephthalate (PET) membrane as an activator was evaluated in the more complex morphology of the mandible. METHODS: A PET membrane coated with hydroxyapatite (HA)/gelatine was placed in the rabbit mandibular bone at lower margin of mandibular molar region underneath periosteum, and screw-fixed. In the experimental group, the membrane was bent and screw-fixed along the lateral surface of the bone, with removal of the outer screw after 7 days followed by activation of the membrane. The experimental group was divided into two subgroups: with and without a waiting period for activation. Three animals were euthanized at 3 weeks and another three at 5 weeks postoperatively. Bone formation was assessed using micro-CT as well as histomorphometric and histological methods. RESULTS: No PET membrane-related complications were observed. The area of newly formed bone and the percentage of new bone in the space created by the stretched periosteum did not significantly differ between the control and experimental groups. However, in the experimental group a greater volume was present after 5 weeks than after 3 weeks. Histologically, bone formation occurred close to the site of cortical bone perforation, with many sinusoidal vessels extending through the perforations in the new bone into the overlying fibrous tissue. Inflammatory cells were not seen in the bone.