Quantification of bone regeneration by virtual slices using non-destructive synchrotron X-ray microtomography

This study demonstrates a non-destructive histomorphometric analysis technique that uses virtual tissue slices obtained with synchrotron radiation X-ray microtomography (SR-μCT), and compared the results to those obtained using conventional hematoxylin-eosin (H&E) photomicrography of regenerated bone in rat calvarial defects grafted with deproteinized bovine bone substitute (Bio-Oss^®). Calvarial defects (diameter, 4 mm) were created in 8 adult male Spraque-Dawley rats and filled with Bio-Oss^®. The percentage of newly formed bone (NB%) was evaluated histomorphometrically using SR-μCT images and photomicrographs (H&E) 3 weeks postoperatively. Osteoconductive new bone formation was observed in the calvarial central defect. Histomorphometric analysis revealed no NB% differences between the SR-μCT and photomicrograph (H&E) groups at 3 weeks (p=0.959). The mean new bone area fractions were 17.62% and 17.95% in the analysis using SR-μCT virtual slices and conventional H&E-stained slices, respectively. Therefore, Bio-Oss^® bone regeneration can be quantified non-destructively using SR-μCT at an accuracy comparable to that obtained using conventional photomicrography.