title: Cranial bone regeneration according to different particle sizes and densities of demineralized dentin matrix in the rabbit model.
abstract: BACKGROUND
  The objective of this study was to place bone graft materials in cranial defects in a rabbit model and compare their bone regenerating ability according to the size and density of demineralized dentin matrix (DDM).
  
  
  METHODS
  We selected nine healthy male rabbits that were raised under the same conditions and that weighed about 3 kg. Two circular defects 8 mm in diameter were created in each side of the cranium. The defects were grafted with DDM using four different particle sizes and densities: 0.1 mL of 0.25- to 1.0-mm particles (group 1); 0.2 mL of 0.25- to 1.0-mm particles (group 2); 0.1 mL of 1.0- to 2.0-mm particles (group 3); and 0.2 mL of 1.0- to 2.0-mm particles (group 4). After 2, 4, and 8 weeks, the rabbits were sacrificed, and bone samples were evaluated by means of histologic, histomorphometric, and quantitative RT-PCR analysis.
  
  
  RESULTS
  In group 1, osteoblast activity and bone formation were greater than in the other three groups on histological examination. In groups 2, 3, and 4, dense connective tissue was seen around original bone even after 8 weeks. Histomorphometric analysis of representative sections in group 1 showed a higher rate of new bone formation, but the difference from the other groups was not statistically significant. RT-PCR analysis indicated a correlation between bone formation and protein (osteonectin and osteopontin) expression.
  
  
  CONCLUSIONS
  DDM with a space between particles of 200 μm was effective in bone formation, suggesting that materials with a small particle size could reasonably be used for bone grafting.
authors.affiliation: Department of Oral and Maxillofacial Surgery, College of Dentistry, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, Chungnam South Korea.
authors.forename: Jin-Woo
authors.initials: JW
authors.lastname: Nam
authors.affiliation: Department of Oral and Maxillofacial Surgery, College of Dentistry, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, Chungnam South Korea.
authors.forename: Moon-Young
authors.initials: MY
authors.lastname: Kim
authors.affiliation: Department of Oral and Maxillofacial Surgery, College of Dentistry, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan, Chungnam South Korea.
authors.forename: Se-Jin
authors.initials: SJ
authors.lastname: Han
keywords: Bone regeneration; Demineralized dentin matrix; Osteoinduction; Particle size