Oral and maxillofacial surgeryOnline only articleAccounting for cranial vault growth in experimental design

ObjectiveEarlier studies have not accounted for continued growth when using the rat calvarial defect model to evaluate bone healing in vivo. The purpose of this study was: 1) to calculate rat cranial vault growth over time; and 2) to determine the effects of accounting for growth on defect healing.Study DesignBilateral parietal defects were created in 10 adult Wistar rats. Serial microscopic computerized tomography scans were performed. Bone mineral content (BMC) measured according to standard technique and repeated accounting for cranial growth over time was compared with the use of parametric and nonparametric tests.ResultsCranial vault growth continued through 22 weeks of age, increasing 7.5% in width and 9.1% in length, and calvarial defects expanded proportionately. BMC was greater within defects accounting for growth 2-12 weeks postoperatively (P < .003).ConclusionsBMC was underestimated through standard analysis, which demonstrates the importance of accounting for cranial growth given advances in serial imaging techniques.