title: The evaluation of the correlation between histomorphometric analysis and micro-computed tomography analysis in AdBMP-2 induced bone regeneration in rat calvarial defects.
abstract: OBJECTIVE
  Micro-computed tomography (micro-CT) has been widely used in the evaluation of regenerated bone tissue but the reliability of micro-CT has not yet been established. This study evaluated the correlation between histomorphometric analysis and micro-CT analysis in performing new bone formation measurement.
  
  
  METHODS
  Critical-size calvarial defects were created using a 8 mm trephine bur in a total of 24 Sprague-Dawley rats, and collagen gel mixed with autogenous rat bone marrow stromal cells (BMSCs) or autogenous rat BMSCs transduced by adenovirus containing bone morphogenic protein-2 (BMP-2) genes was loaded into the defect site. In the control group, collagen gel alone was loaded into the defect. After 2 and 4 weeks, the animals were euthanized and calvaria containing defects were harvested. Micro-CT analysis and histomorphometric analysis of each sample were accomplished and the statistical evaluation about the correlation between both analyses was performed.
  
  
  RESULTS
  New bone formation of the BMP-2 group was greater than that of the other groups at 2 and 4 weeks in both histomorphometric analysis and micro-CT analysis (P=0.026, P=0.034). Histomorphometric analysis of representative sections showed similar results to histomorphometric analysis with a mean value of 3 sections. Measurement of new bone formation was highly correlated between histomorphometric analysis and micro-CT analysis, especially at the low lower threshold level at 2 weeks (adjusted r(2)=0.907, P<0.001). New bone formation of the BMP-2 group analyzed by micro-CT tended to decline sharply with an increasing lower threshold level, and it was statistically significant (P<0.001).
  
  
  CONCLUSIONS
  Both histomorphometric analysis and micro-CT analysis were valid methods for measurement of the new bone in rat calvarial defects and the ability to detect the new bone in micro-CT analysis was highly influenced by the threshold level in the BMP-2 group at early stage.
authors.affiliation: Department of Periodontology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea.
authors.forename: Shin-Young
authors.initials: SY
authors.lastname: Park
authors.forename: Kyoung-Hwa
authors.initials: KH
authors.lastname: Kim
authors.forename: Ki-Tae
authors.initials: KT
authors.lastname: Koo
authors.forename: Kang-Woon
authors.initials: KW
authors.lastname: Lee
authors.forename: Yong-Moo
authors.initials: YM
authors.lastname: Lee
authors.forename: Chong-Pyoung
authors.initials: CP
authors.lastname: Chung
authors.forename: Yang-Jo
authors.initials: YJ
authors.lastname: Seol
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