Confocal Laser Scanning Microscopic Observation of Newly-formed Bone Growth after Coral Filling in Dog Bone Defect

Optimal bone filling materials that act as a scaffold for the repair of bone defects should possess, histocompatibility, and afford conduction of new bone formation without toxicity or allergic factors. In addition, the materials should ultimatedly be resolved and replaced by new bone. In this study, to develop new bone filling materials that promote bone formation and bone growth, we implanted coral in bone defects and observed the newly-formed bone by confocal laser scanning microscopy (CLSM). In 3 adult male beagles, bone defects were made in the right and left femora and tibiae under general anesthesia. These defects were either filled with coral blocks or left without any filling material. After 4 weeks, calcein was administered. One week later, the animals were euthanized under general anesthesia, and the femora and tibiae were removed and fixed in formalin. The specimens were divided into two portions: one is for CLSM observation and the other for histopathological observation. The formation of bone and bone marrow was seen in holes without filling, but only slight bone growth, i.e., increase in bone mass was seen. In the holes with coral filling materials, they were resorbed by giant cells. Furthermore, new bone and bone growth were noted, while lymphocyte infiltration was slight in all holes. Since resorption of the coral inserted into the bone defect was observed, we concluded that coral could be useful for bone regeneration.