Changes in the shape and ultrastructure of the articular disk of rat following postural hyperpropulsor / 대한치과교정학회지

This study was conducted to examine the changes in the shape of the Sprague-Dawley rats' articular disk following postural hyperpropulsion by observing their articular specimens through light and electronic microscopes after following 2-week and 4-week postural hyperpropulsion from their four weeks of age. The findings of this study are summarized as follows, It was shown that as compared with the control group, the experimental group indicated a significant increase in thickness of the 2-week groups' anterior and postreior portion of the articular disc. The experimental group showed statistically more significant increase in thickness of the 4-week groups' anterior portion of the articular disc than the control group. Light micrograph showed that the experimental group had more fibroblast in the anterior portion of the 2-week and 4-week groups than the comparing group. The 2-week groups showed in the findings through the electronic microscope that there were found the well developed and dilated HER which seems to actively synthesize the extracellular matrix including collagen, the cells with the well developed RER without distention which seems to actively synthesize the intracellular microfilaments due to the well developed free ribosome, and the typical chondroid cells. In addition, there was more fibroblast cell with the distended and well developed RER in the anterior area of the experimental group than that of the control group. The 4 week experimental group's anterior area of the disk had more cells than that of the control group while fibroblast with the well developed RER and free ribosome was quite abundant. Based on the above result of this study, it was shown that the functional hyperpropulsion of the mandible causes the changes in the nature of the mechanical load to the certain portion of the articular disk. As a result, it seems that there may be occurred some changes in morphology of the disc by adaptation or confrontation with these changes at the cellular level.

A longitudinal study on the soft tissue facial profile change: Study report from 9 to 13 years of age / 대한치과교정학회지

This investigation was undertaken to know how soft tissue facial profile could be changed with age. The 3 serial lateral cephalometric roentgenograms of the twenty nine boys and twenty six girls between 9 and 13 years of age were studied and the findings seemed to warrant the following conclusions. 1. The author made the tables of means, standard deviations in each item, sex, age. 2. Soft tissue facial angle, soft tissue facial convexity including the nose tended to increase, but others tended to remain relatively stable. 3. Facial soft tissue thickness increased with age and the growth of facial soft tissue in the middle region (point A, LS, LI) was greater than others in the facial region. 4. In the soft tissue vertical proportions, G1'-Sn/Sn-Me' was 1.1, Sn-St/St-Me' was 0.51:1, Sn-LI/LI-Me' was 0.82:1 and those were stable with age.