IADR Abstract Archives
Resorption property of Carbonate Apatite Bone Graft Substitute
Objectives: Carbonate apatite bone graft substitute containing similar amounts of carbonate ion with human bone (Cytrans Granules) was developed by using phase transformation based on dissolution-precipitation reactions. In this study, we aimed to evaluate initial and long-term resorption of Cytrans Granules.
Methods: Cytrans Granules (size: 0.3-0.6 mm) and sintered hydroxyapatite granules (size: 0.3-0.5 mm) was used. Initial in vitro dissolution at pH 5.5 and pH 7.3 was evaluated by test method based on ISO 13175-3. Long-term in vivo resorption was evaluated by using rabbit femoral defect model under the protocol approved by Institutional Animal Care and Use Committee of Hamri Co., Ltd., which has been approved by AAALAC International. Each sample was implanted to bone defect (φ5 mm×8 mm) created in femoral shaft of Japanese white rabbit (over 18 weeks old, male). After healing period of 2, 4, 12, 26 weeks and 2 years, new bone area and remaining granule area were measured from histological section by using Image J (NIH).
Results: Both Cytrans Granules and sintered hydroxyapatite was stable at neutral pH resembling body fluid, and only Cytrans Granules was dissolved at weak acidic pH similar to Howship lacunae. Remaining granule area of sintered hydroxyapatite did not change among test period. Granule size of Cytrans Granules got smaller over time, and the remaining granule area was 75% at 2 weeks, 73% at 4 weeks, 51% at 12 weeks, 38% at 26 weeks and 28% at 2 years, where the area of before implantation was considered as 100%. Granules were covered with newly formed bone at 12 weeks, and trabecular structure like bone was regenerated as the granules were resorbed.
Conclusions: It is suggested that Cytrans Granules is gradually resorbed by keeping the bone volume, and completely replaced with newly formed bone in about 2 years.
Methods: Cytrans Granules (size: 0.3-0.6 mm) and sintered hydroxyapatite granules (size: 0.3-0.5 mm) was used. Initial in vitro dissolution at pH 5.5 and pH 7.3 was evaluated by test method based on ISO 13175-3. Long-term in vivo resorption was evaluated by using rabbit femoral defect model under the protocol approved by Institutional Animal Care and Use Committee of Hamri Co., Ltd., which has been approved by AAALAC International. Each sample was implanted to bone defect (φ5 mm×8 mm) created in femoral shaft of Japanese white rabbit (over 18 weeks old, male). After healing period of 2, 4, 12, 26 weeks and 2 years, new bone area and remaining granule area were measured from histological section by using Image J (NIH).
Results: Both Cytrans Granules and sintered hydroxyapatite was stable at neutral pH resembling body fluid, and only Cytrans Granules was dissolved at weak acidic pH similar to Howship lacunae. Remaining granule area of sintered hydroxyapatite did not change among test period. Granule size of Cytrans Granules got smaller over time, and the remaining granule area was 75% at 2 weeks, 73% at 4 weeks, 51% at 12 weeks, 38% at 26 weeks and 28% at 2 years, where the area of before implantation was considered as 100%. Granules were covered with newly formed bone at 12 weeks, and trabecular structure like bone was regenerated as the granules were resorbed.
Conclusions: It is suggested that Cytrans Granules is gradually resorbed by keeping the bone volume, and completely replaced with newly formed bone in about 2 years.