title: Histological and histomorphometrical comparative study of the degradation and osteoconductive characteristics of alpha- and beta-tricalcium phosphate in block grafts.
abstract: The purpose of the present study was to compare alpha- and beta-tricalcium phosphate (TCP) as bone graft material for augmenting highly resorbed alveolar ridges. The cranial bones of 15 rabbits were used. Three titanium chambers filled with porous blocks of alpha-TCP, beta-TCP, or blood clots were placed in each slit. The two TCP blocks had similar inner/outer structures and purities. Animals were sacrificed after 2, 4, and 8 weeks. Specimens were embedded in polyester resin as nondecalcified specimens, and evaluated both histologically and histomorphometrically. In both TCP groups, blocks had hardly degraded at 2 weeks while in the alpha-TCP group, the block had notably started degrading after 4 weeks. In the beta-TCP group, degradation began at 4 weeks and this degradation had increased just slightly after 8 weeks. The alpha-TCP block degraded significantly more than the beta-TCP block. Residual alpha-TCP particles surrounded by newly formed bone decreased over time, and both particles and newly formed bone were simultaneously absorbed by osteoclast-like cells. These observations suggest that residual alpha-TCP particles surrounded by newly formed bone may disappear progressively from bone and could be incorporated into the bone remodeling cycle in combination with newly formed bone.
authors.affiliation: Oral Implantology and Regenerative Dental Medicine, Tokyo Medical and Dental University,1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Ornette-coleman.impl@tmd.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamada
authors.forename: Makoto
authors.initials: M
authors.lastname: Shiota
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Shohei
authors.initials: S
authors.lastname: Kasugai
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D016723:Bone Remodeling / Q000187:drug effects*; D018786:Bone Substitutes / Q000378:metabolism* / Q000494:pharmacology; D001842:Bone and Bones / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002130:Calcium Phosphates / Q000378:metabolism* / Q000494:pharmacology; D011817:Rabbits; D014025:Titanium / Q000737:chemistry; D019737:Transplants
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485817:beta-tricalcium phosphate; D014025:Titanium