Abstract
The automatic masticatory movement analyzing system was used to investigate the pattern of masticatory path in 78 normal subjects. After classifying the pattern, examining the frequency of each pattern, and investigating the opening and closing angle the following results were obtained.
1. 8 patterns (I-VIII) were observed.
I: smooth opening toward working side, and convex closing.
II: opening similar to I, but concave closing.
III: opening toward working side after initially toward non-working side, and convex closing.
IV: opening similar to III, but concave closing.
V: convex opening, and closing with similar path.
VI: opening more toward working side than closing. VII: crossing.
VIII: creating a line.
2. The catalog for classification was composed of 4 combinations.
3. The most frequent pattern on the habitual, non-habitual, and both side was I, followed by III, II, etc. Also I through IV constitute 85.3%, and I and III constitute 71.8% of the total.
4. The most common pattern in individual subject was I for both side, followed by III for both.
5. The opening angles for I, II or III, IV were similar. The closing angles were significantly smaller in II, IV than in I, III. Also the closing angle for I, III was 47.3±7.6°.
6. It is suggested that a normal mastication was mainly I or III, must exhibit convex closing path, with a functional anterior guidance (Iateral incisal path) of approximately 40-55° to mid plane (35-50° to horizontal plane).
