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Hydroxyapatite (HA) [Ca10 (PO4)6 (OH)2] has a high degree of chemical similarity with the mineral composition of animal bone. Hydroxyapatite fiber scaffold (HAF) is a biological material with a highly interconnected porous structure. We aimed to study the physical and biological characteristics of HAF and compare the osteogenic effects of HAF, natural osteogenic materials (NOM), and carbonate apatite (CO3Ap-DP) in the parietal defects of a rabbit's skull. X-ray analysis and histological assessment showed that HAF followed a trend of early initial osteogenesis and bone trabecular structure formation, especially at the cortical bone portion. Compared to the other two materials, HAF was more absorptive. Results indicated that HAF had the same osteoconductive and new bone formation properties as NOM and CO3Ap-DP. These findings will provide options for future material development and novel protocols for use in surgeries, ultimately leading to better patient outcomes.

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Background : The replacement of lost natural teeth using osseointegrated implants require adequate bone volume permitting their anchorage.Many studies have shown potential advantages of stem-cell based therapies in bone tissue engineering. Periosteal cells have been suggested as a promising source for bone tissue engineering, and low-intensity pulsed ultrasound (LIPUS) has shown successful bone healing of delayed unions, non-unions and simulated fracture healing in animal models and in clinical treatments.Aim/Hypothesis : The aim of this study was to investigate the effect of LIPUS on the proliferation and the osteogenic differentiation of murine calvarial derived periosteal cells.Materials and Methods : Four-week-old SLC ICR female mice were euthanized, and then their calvarias were extracted and washed with phosphate-buffered saline (PBS). Six hundred mg gelatin was inserted inside a 60 mm culture dish and immersed in a 6 ml culture medium. The periosteum was derived from the calvarias and put it onto the gelatin. Then the gelatin was inverted upside-down and incubated at 37°C with 5% CO2. The culture medium was changed every 3 days. Cells at the passage of three were treated with LIPUS with an intensity of 30 mW cm2, frequency of 3 MHz, pulse repetition frequency (PRF) of 1 kHz and exposure time of 20 min per day up to 21 days. The cell proliferation and viability were analyzed by cell counting kit-8 (CCK-8) assay, PrestoBlue assay and Live Dead Cell Assay. Osteogenic differentiation was determined by alkaline phosphatase (ALP) staining, ALP activity assay, alizarin red staining and RT-real-time-PCR of osteogenic marker genes.Results : Cell proliferation is significantly accelerated by LIPUS more than that of the control group. Furthermore, more osteogenic differentiation was observed in LIPUS treated groups. Conclusion and Clinical Implications :The results suggested that LIPUS could enhance cell proliferation and osteogenic differentiation of murine calvarial derived periosteal cells and could be part of effective treatment methods for future clinical applications.