Abstract
In a previous study, we examined a method for evaluating masticatory function in adults using a laser beam with occlusal balance as an index. It is known that the permeable laser method is easy to apply to infants. Making use of the strong point of the laser, we carried out this study to evaluate the occlusal balance in children in the primary dentition period. A total of 92 infants attending a nursery school were enrolled into this study. Those children who came under Hellman's dental age IIA were divided into group A (dft=0), group B (1≦dft≦5) and group C (6≦dft). Those in the IIC were classified as group D. Comparisons were made between these four groups for occlusal contact area, volume of coronal portion, and centroid. Especially, differences in occlusal balance were carefully studied if changes in occlusal balance could be measured by use of such new indices as the rate of displacement ratio and anterior-posterior ratio. Our findings were as follows : 1. Comparisons of mean occlusal contact area between groups revealed that the values for group D exceeded those for any group that came under the IIA. 2. Significant differences were noted between group A and group D in the rate of displacement, between group A and group C in the anterior-posterior ratio, and between group C and group D in each mean value (p<0.05). 3. Single regression analyses of values obtained for each evaluation item showed that there was a positive correlation between the rate of displacement and dft (r=0.28, p<0.05) and also between the volume of the coronal portion and the anterior-posterior ratio (r=0.60, p<0.01). From these findings, we concluded that differences in occlusal balance could also be examined by our method in infants in the primary dentition period. In terms of homeostasis during the period of growth and grasping the influence of caries on mastication, our findings suggested that observing occlusal balance would be very useful.
