Measurement of interspaces after filling bone defects with different sizes of β-tricalcium phosphate granules : Comparison between experimental animals and defect models

Following tooth loss, alveolar bone is resorbed over time. In cases with high levels of absorbed alveolar bone, bone augmentation by use of various artificial materials is often performed in combination with oral implant treatment. Beta-tricalcium phosphate (βTCP) is an artificial bone supply material used for bone augmentation. It has a high level of osteoconductivity, as it is absorbed relatively quickly and replaced with autologous bone, and has recently been applied in the fields of orthopedic medicine and dentistry. When β-TCP granules are used for filling bone defects, microvascular formation advances in the granule interspaces, which is followed by bone formation to encircle the granules. 23 Accordingly, the granule interspaces are considered important for microvascular formation and subsequent new bone formation. We used granules of different sizes in animal experiments to measure granule interspaces and investigated whether adequate space required for microvascular formation could be obtained when the granules were added in vivo. In addition, we measured the interspaces in a bone defect model and compared the results with those obtained in the animal experiments. We also analyzed the usefulness of a bone defect model as a substitute for animal experimentation from the standpoint of animal welfare.