Abstract
The purpose of this clinical study was to develop the method for comparing the morphological shape of the neutral zone, recorded by a single functional oral movement.
The neutral zone during function was recorded with impression plaster. The function was such as maximum jaw opening, pronunciation of “i” and “u”: and the movement of the tip of tongue toward posterior and upward. These records were cut in frontal plane and these sections were observed in piles with computer graphics.
Findings were as follows:
1. Maximum jaw opening; The buccal an d sublingual region of neutral zone protruded in shapes.
2. Pronunciation of “i”; The buccal region of neutral zone caved in hardly, and its sublingual region protruded more than that of any other functional movement in this study.
3. Pronunciation of “u”; The neutral zone was almost same shape as that of the ma ximum jaw opening. But this shape caved in at the buccal region of first premolar.
4. The movement of the tip of tongue toward the posterior and upward; The buccal region of neutral zone protruded and the sublingual region caved in more than any othe r neutral zone of functional movement in this study. This tendency was more obvious at the molar region than at the premolar region.
From these results, it was recognized that the method which we developed in this study w as very effective to analyze shape of neutral zones.
