Changes in Cortical Bone Mineralization in the Developing Mandible: A Three-Dimensional Quantitative Computed Tomography Study

Abstract

Quantitative computed tomography (QCT) was completed in 34 subjects between the ages of 9 and 33 years with symmetrical mandibles in order to investigate the three-dimensional cortical bone mineral density (BMD) distribution in the mandible. The number and distribution of the pixels were determined at three levels: (1) representing the entire mandibular bone; (2) the cortical bone at 60% above the baseline defined as the segmentation level (around 1050 mg/cm 3 ) and representative of only cortical bone; and (3) the highest mineralized cortical bone (>1250 mg/cm 3 ). The geometrical distribution of the highest mineralized areas was evaluated by three-dimensional reconstruction of the images. The total number of pixels for the entire mandible increased significantly at each time point represented at four increasing ages groups (9 -11 years of age, 12-14 years of age, 15-17 years of age, and >18 years of age). The male and female subjects had a similar total number of pixels for the entire mandible before the age of 11, but the male subjects showed a significantly larger total number of mandibular pixels after that age. Comparison of the number of pixels for pure cortical bone (60% segmentation level) and the highest mineralized cortical bone indicated a significant increase with maturation with the greatest change occurring between the 13-year and 16-year age groups. However, the ratio of cortical bone/total bone increased at a more rapid rate in the male subjects and reached a plateau by the 16-year age group, showing distinct differences in mineralization of the mandible between the sexes. (J Bone Miner Res 2000;15:700 -709)

Changes in cortical bone mineralization in the mouse mandible with regenerated condyle

“…This is consistent with the finding of M aki et al. (9) who showed that cortical bone mineralization in the mandible increased with age in the growing individual. These results are also in agreement with those of our previous study, which demonstrated that mandibular advancement enables regeneration of cartilaginous tissues on injured condyles and recovery of the reduced mandibular growth, leading to correction of the lateral shift of the mandible (8).…”

“…The present study has revealed that by using a functional appliance to reposition the mandible forward, the growth capability of the condylar head can be activated and the cortical bone mineral content, area and density, as measured by pQCT in the damaged mandible, is brought to control values. This is consistent with the finding of Maki et al (9) who showed that cortical bone mineralization in the mandible increased with age in the growing individual. These results are also in agreement with those of our previous study, which demonstrated that mandibular advancement enables regeneration of cartilaginous tissues on injured condyles and recovery of the reduced mandibular growth, leading to correction of the lateral shift of the mandible (8).…”

Material property variation of mandibular symphyseal bone in colobine monkeys

“…Among our small sample this is quite clearly not the case, as the lone C. polykomos female is the largest representative among the three individuals of this species. A hormonal factor for influencing the sex differences is also possible, although known sex discrepancies in mineralization (Hannan et al, 1992;Cerroni et al, 2000;Maki et al, 2000) are opposite of those observed here; that is, females are typically distinguished by lower bone mineral density which likely results in decreased bone stiffness.…”

Accuracy of Quantitative Computed Tomography Bone Mineral Density Measurements in Mandibles: A Cadaveric Study

“…22 In this way, in order to avoid failures in QCT, BMD should be calculated by measuring HU and relating the values obtained to a calibration bone phantom with a predetermined mineral density (MD). 23 Different calibration standards containing CaCO 3 24 or calcium hydroxyapatite (HA) in either polyurethane 25,26 or water-equivalent base materials have been used. Use of the actual bone mineral with calcium HA will minimize the dependence of BMD on CT scanning conditions.…”