Study on Masticatory System Development, by Observing Growth, Function and Eating Behavior as Indicators.

本研究试图从形态、功能和行为三个方面建立一个定量的咀嚼系统发育量表。1995年，对前人的研究进行了综述，并选取了几项指标来评价婴幼儿和儿童期咀嚼系统的形态、功能和行为发育。几乎没有指数来衡量儿童的进食行为或能力。由此，建立了评价进食行为进步的标准量表--进食指数。1996年，对横断面数据进行了分析，以考虑指数的特征并检验指数之间的相关性。1997年，对形态数据(牙齿检查和测量)、功能数据(咬肌肌电活动、咀嚼效率和咬合力)、行为数据(进食指数和进食行为观察)进行纵向分析。随着年龄的增长，牙弓变大，发育空间变大，咬肌活动幅度增大，咀嚼节律趋于稳定，咀嚼效率、咬合力和进食指数增加。这些指标之间存在显著的相关性。通过主成分分析将这些指标组合成发育变量。在出生后两年内，观察到个体内存在较大的差异。特别是在出生后18个月内，功能指标并不可靠。然而，有人认为，这个变量(发育变量)在2岁或3岁时可以预测5岁或6岁时的进一步发展。

It was attempted in this study to establish a quantitative developmental scale of masticatory system approaching from morphological, functional and behavioral aspects. In 1995, the previous studies were reviewed and several indices were selected to evaluate morphological, functional and behavioral development of the masticatory system in infanthood and childhood. There were few indices to scale eating behavior or ability for children. Thus, a standard scale for evaluating the progress of eating behavior, 'Eating food index' was established. In 1996, the crosssectional data was analyzed to consider characters of index and test correlation among indices. In 1997, morphological data (dental examination and measurement), functional data (EMG of masseter muscle activity, chewing efficiency, and bite force), behavioral data (eating food index and observing eating behavior) was analyzed longitudinally. Dental arch size became bigger, developmental space become prominent, amplitude of masseter muscle activity increased, chewing rhythm became stable, chewing efficiency, bite force and Eating food index increased with ages. These indices were related each other significantly. Developmental variable was composed from these indices by principal component analysis. During two years after birth, large variance within individuals were observed. Specially, during eighteen months after birth, functional indices were not reliable. However, it was suggested that this variable (developmental variable) in two or three years old could predict further development in five or six years old.