Representative images of bone internal structure of the bone surrounding the IC. In (A-D), the 3D image constructions of dentulous maxilla and edentulous maxilla were cut in the labiopalatal direction and differences in properties pertaining to the structure of bone were observed. In (B) and (D), the samples were further sliced and observed in detail. (A, B) Relatively thick cortical bone; the cancellous bone travels in a direction parallel to the longitudinal axis of the tooth, and the density is low. (C, D) Cortical bone is especially thin in edentulous maxilla, and the cancellous bone travels with irregular arraying of fine trabecular bone. The density is very high.