title: Effects of granule size on the osteoconductivity of bovine and synthetic hydroxyapatite: a histologic and histometric study in dogs.
abstract: Two bovine hydroxyapatites (BHAs), one with granule size of 150 to 200 microm and one with granule size of 300 to 329 micro, and 2 synthetic hydroxyapatites (SHAs), with granule size of 150 and 300 microm, respectively, were compared for effectiveness in repairing circumferential bone defects in dogs. The hydroxyapatites (HAs) were characterized through powder x-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Three trephined bone defects (5.0 mm wide x 4 mm long) were created in the humeruses of 8 dogs. In a random manner, the defects on each side were treated with either BHA with small granules (BHA[s]), BHA with large granules (BHA[L]), SHA with small granules (SHA[s]), SHA with large granules (SHA[L]), or left to heal unaided (bilateral control). Four dogs were sacrificed after 6 and 12 postoperative weeks, respectively. Ground sections of each defect were submitted to histologic and histomorphometric analysis (percentage of area occupied by bone, bone marrow, and biomaterial). As a rule, the HA granules exhibited direct bone contact, regardless of the origin and the size of the granules. Control sites were related and had an increased amount of connective tissue infiltration. At 12 weeks, BHA(s) exhibited improved bone formation compared with SHA(s) and SHA(L). The SHA(s) delivered reduced amounts of bone compared with the remaining groups (control included). The area of bone measured in BHA(s) sites was significantly higher at 12 weeks than 6 weeks. The XRD revealed the tested HA samples to be highly crystalline, while BHA appeared with rougher surface at SEM analysis. The BHA(s) performed better than the SHA(s) and SHA(L), as assessed by the amount of bone measured in both implantation sites at 12 weeks. The BHA's material characteristic itself rather than granules size accounted for the distinctive biological behavior. The increased roughness of the BHAs' surface, as assessed through SEM, seemed to benefit the osteoconduction process.
authors.affiliation: Department of Oral and Maxillofacial Surgery and Periodontics, Faculty of Dentistry of Ribeirão Preto, The University of São Paulo at Ribeirão Preto, SP, Brazil.
authors.forename: Alexandre L
authors.initials: AL
authors.lastname: Carvalho
authors.forename: Paulo E P
authors.initials: PE
authors.lastname: Faria
authors.forename: Marcio F M
authors.initials: MF
authors.lastname: Grisi
authors.forename: Sergio L S
authors.initials: SL
authors.lastname: Souza
authors.forename: Mario Júnior
authors.initials: MJ
authors.lastname: Taba
authors.forename: Daniela B
authors.initials: DB
authors.lastname: Palioto
authors.forename: Arthur B Júnior
authors.initials: AB
authors.lastname: Novaes
authors.forename: Alexandre F
authors.initials: AF
authors.lastname: Fraga
authors.forename: L Sevgi
authors.initials: LS
authors.lastname: Ozyegin
authors.forename: Faik N
authors.initials: FN
authors.lastname: Oktar
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Salata
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000502:physiology*; D018786:Bone Substitutes / Q000737:chemistry*; D002417:Cattle; D018360:Crystallography, X-Ray; D004285:Dogs; D006811:Humerus / Q000601:surgery; D006882:Hydroxyapatites / Q000737:chemistry*; D008297:Male; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D018709:Statistics, Nonparametric; D013499:Surface Properties
chemical_list: D018786:Bone Substitutes; D006882:Hydroxyapatites