The longitudinal growth changes of craniofacial structure in Korean adult (during the age of 24 to 31) / 대한치과교정학회지

Recently, according to the increase of adult patient, it is neccessory to understand the growth changes of adult after cessation of active pubertal growth in clinical orthodontics. The purpose of this study was to investigate the growth changes of craniofacial structure after active growth period(afult) in order to use reference in clinical orthodontics. Authors followed the 40 sample(male 25, female 15) from 24 to 31 years of age. By analyzing the serial cephalograms, authors could get the following findings. ? The mandible rotated clockwise in female, but not in male, and no incremental growth change in both genders. ? The anterior facial height and lower anterior facial height were increased in both genders, the increase of lower anterior facial height exceed the posterior facial height increase in famale. ? The cranial base was stable throughout observation period. ? The upper incisors uprighted slightly in female. ? There were quite great the individual variation in the growth change of ceaniofacial structure in adult.

The effects of mechanical stress on alkaline phosphatase activity of MC3T3-E1 cells / 대한치과교정학회지

Orthodontic force is a mechanical stress controlling both of tooth movement and skeletal growth. The mechanical stress stimulate bone cells that may exert some influence on bone remodeling. The purpose of this study was to evaluate the difference in cellular activity depending on mechanical stresses such as compressive and tensile force by determining the alkaline phosphatase(ALP) activity. A clonal osteogenic cell line MC3T3-E1 was seeded into a 24-well plate(2x 10(4)/well). At the confluent phase, a continuous compressive hydrostatic pressure(25g/cm2, 300g/cm2) and continuous tensile hydrostatic pressure( -25g/cm2, -300g/cm2) were applied for 4, 6, 10, 14, 18, 20 days respectively by a diaphgragm pump. At the end of the stimulation period, cell layers were prepared for ALP activity assay. The ALP activity of the compressive group increased more than that of the tensile group at same force magnitude, whereas the cells responded to a similar pattern regardless of the type of mechanical stress. The ALP activity of the compressive and tensile group turned into the level of the control group as the length of time increased. These results indicated that a mechanical stress may be more effective on cellular activity during active cellular proliferation and differentiation periods. The time to achieve maximum ALP activity was delayed as the mechanical stress increased in both the compressive and the tensile group. Accordingly, the magnitude of the stress rather than the type of mechanical stress may have more influence on cellular activity.