title: 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/cm3) and representative of only cortical bone; and (3) the highest mineralized cortical bone (>1250 mg/cm3). 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.
authors.affiliation: Department of Orthodontics, Showa University, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Maki
authors.forename: A
authors.initials: A
authors.lastname: Miller
authors.forename: T
authors.initials: T
authors.lastname: Okano
authors.forename: Y
authors.initials: Y
authors.lastname: Shibasaki
mesh_terms: D000293:Adolescent; D000328:Adult; D015519:Bone Density; D002113:Calcification, Physiologic / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000254:growth & development / Q000502:physiology*; D011859:Radiography; D015898:Tomography Scanners, X-Ray Computed