アパタイト・ブロックにより再建した下顎骨へのアパタイト・インプラントならびに骨付きアパタイト・インプラントの適用

Abstract

Applying apatite implants into apatite blocks reconstructed mandibulae was performed in dogs. Apatite implants (A.I.). 5mm in diameter and 9mm in length, and implant for bone-apatite implants (B.A.T.) 4mm in diameter and 9mm in length were used in this experiment. The sizes of block (Block) were 25mm in length and 13mm in height and the porosity rate was about 60%.After resecting bilateral alveolar parts of mandibulae, Blocks were placed into the defect areas ligated by nylon wires. At the same time implants were placed into ilia. After 3 months, implants covered with iliac bone were taken out from ilia, with A.I., placed into Blocks of the mandibulae. 3 months later, mandibulae and ilia were taken out and prepared for undecalcified specimens. The surrounding tissues of A.I. and B.A.T. were examined.A lot of neogenetic bone was formed along the macropore inside Blocks. The neogenetic bone showed different kinds of differentiation. It was higher in the mesial, distal, and bottom areas near the mandibulae and it was lower in the area toward the internal of Blocks. It was because of the distance from the mandibulae, and the placement of A.I. and B.A.T. The surrounding tissues of A.I. showed lower differentiation, as compared with B.A.I.'s.Apatite of B.A.T. was covered with grafted bone which was extensively connected with neogenetic bone inside Blocks. B.A.T. showed osseointegration between apatite and grafted bone in wide range. Grafted bone was connected the cutting surface of Blocks and neogenetic bone inside macropore, apatite was connected with the neogenetic bone formed inside Blocks through grafted bone. There was a lot of neogenetic bone found in the lingual area of B.A.I., as compared with the buccal area. Bone remodeling was shown between grafted bone and neogenetic bone.Around A.I., there was more fibrous connective tissue binding with than neogenetic bone. Fibrous connective tissue was also seen in the area where the tipper wall of mandibular canal was removed during the placement of Blocks. Fibrous connective tissue was continuous inside Blocks.From above it was implied that it was possible to apply the apatite implants into the apatite blocks reconstructed mandibulae.