Bone Mineral Density Analysis for Evaluation of Cervical Vertebral Maturation
Objective: The cervical vertebral maturation (CVM) method is a useful tool for detecting the status of mandibular growth. However, the current CVM method based on two dimensional cephalometric radiographs may not fully include all factors that may be involved in bone maturation. For instance, the current CVM cannot account for changes of bone mineral density (BMD), which result from active bone remodeling during growth. Thus, the objective of this study was to describe bone density changes in the cervical vertebrae occurring during the period of adolescent mandibular growth and development.Materials and methods: Cone beam computerized tomography (CBCT) images were obtained from 41 patients before and after orthodontic treatments. Patients were 14.47¿1.42 years and 16.15¿1.38 years before and after treatments, respectively. IRB approval was obtained for this retrospective CBCT analysis. Two cervical vertebrae (C2 and C3) were digitally isolated using the three dimensional CBCT. Gray level histogram of each vertebra was obtained using CT attenuation values of voxels. Mean and standard deviation (SD) of gray level histogram were obtained. Percentage (%) differences of gray level parameters between C2 and C3 ((C3-C2)/(C2+C3)/2)*100) were computed. A paired t-test was utilized to compare the % differences between before and after treatments. Results: The % difference of Mean significantly increased after treatment (3.06¿1.11%) (p<0.001) compared to before treatment (1.22¿1.76%) while the SD before treatment (-6.62¿6.27%) was significantly greater than after treatment (-1.97¿5.62%) (p<0.002). Conclusions: The Mean and variability (SD) of gray levels account for a degree of bone mineralization and active remodeling, respectively. It was found that the growth rate of C2 is about twice that of C3 at 14.5 years but the rates of both cervical vertebrae decreased to the same level at 16.5 years old. Taken together, the current results indicate that the active bone remodeling of C2 decreased while bone mineralization of C3 which undergoes less bone remodeling increased during vertebral maturation.
Dentistry, Developmental Biology, Health Care, Radiology, Cervical vertebral maturation, bone density, CBCT
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