ABSTRACT
To investigate the longitudinal sagittal growth changes of maxilla and mandible according to the quantitative cervical vertebral maturation (QCVM) for adolescents with normal occlusion,mixed longitudinal data were used.The samples included 87 adolescents aged from 8 to 18 y old with normal occlusion (32 males,55 females) selected from 901 candidates.Sequential lateral cephalograms and hand-wrist films were taken once a year,lasting for 6 y.The longitudinal sagittal growth changes of maxilla and mandible according to QCVM were measured.There were some significant differences between maxilla and mandible according to QCVM.The sagittal growth change of maxilla showed a trend towards high velocity→decelerating velocity→completing velocity from QCVM stage Ⅰ to stage Ⅳ.The sagittal growth change of mandible showed a trend towards accelerating velocity→high velocity→decelerating velocity→completing velocity from QCVM stage Ⅰ to stage IV.With sagittal relationship,growth magnitude was almost the same between maxilla and mandible at QCVM stage Ⅰ.At stage Ⅱ the growth of mandible exceeded that of maxilla and growth in mandible continued at stages Ⅲ and Ⅳ,while the maxilla ceased to grow.Growth magnitude was greater and the growth duration was longer with male mandible.It is concluded that the longitudinal sagittal growth changes of maxilla and mandible on the basis of QCVM is of value in the orthodontic practice.
ABSTRACT
The purpose of this study was to determine the total Bolton index (TBI) and anterior Bolton index (ABI), evaluate the clinical significance of tooth size discrepancies and the influence of gender variation of mesiodistal tooth width on Bolton Index and estimate which tooth has the greatest influence on Bolton Index. A total of 110 pairs of pretreatment dental study casts (41 male and 69female) were selected from patients treated in Department of Orthodontics of Union Hospital in Wuhan, China. A sliding dental Vernier caliper was used for the measurement of the mesiodistal tooth width. Descriptive statistical mean values, standard deviation, standard error of the mean values, coefficient of variance and the t-test were used for the statistical analysis of the data. The study found that TBI, ABI and the total sum of teeth width had no significant difference between male and female.Male group indicated that Bolton Index (BI) was mostly influenced by the width of lower right second premolar, whereas female group showed that BI was mostly influenced by the width of both the right and left maxillary lateral incisor.