1996 Volume 2 Issue 2 Pages 173-178
The purpose of this study was to examine whether there is any correlation between tooth guidance and masticatory movements in different chewing patterns. Masticatory movements and lateral movements were measured on 33 normal young adults using the 3-dimensional Mandibular Movement Analyzing System in six-degrees of freedom. The tooth guidance (TG) was evaluated as the inclination of the incisal path during the lateral movements. The shapes of the incisal masticatory paths were divided into four types of masticatory patterns, which were normal type (Type I ), reverse type (Type II ), and two cross types (Type III and IV) . The pattern of Type III was the envelope that had the closing path in working-side area relative to the opening path within the intercuspal range, and that of Type IV the one that had the opening path in working-side area relative to the closing path. The variables to analyze the masticatory movements were closing angle of the incisal path (MA) at 0.5 mm and 5.0 mm closing level below the inter-cuspal position. The mean value of MA in each pattern was calculated on each subject. The results were as follows:
1. There were significant conelations between TG and MA at 0.5mm closing level (r=0.46, p<0.01) and no significant correlation at 5.0mm closing level in Type I.
2. There were no significant correlations at 0.5mm and 5.0mm closing level in Type II.
3. There were no significant correlations at 0.5mm and 5.0mm closing level in Type III.
4. There were significant correlations at 0.5mm and 5.0mm closing level in Type IV. (0.5mm level, r=0.85, p<0.05, 5.0mm level, r=0.93, p<0.01)
It is suggested that the relation between tooth guidance and masticatory movements varies according to the type of masticatory pattern.
