Two-dimensional study of the neutral zone at different occlusal vertical heights.

A new technique was developed to locate the neutral zone. The neutral zone was studied on two groups of patients with prominent or flat residual alveolar ridges. The neutral zone was determined for each patient at three vertical heights. It was studied both vertically and horizontally. The width of the neutral zone was measured at different regions with these conclusions: 1. The width of the neutral zone is minimum at the level of the occlusal plane and increases gradually as it goes up and down. 2. The width of the neutral zone is also minimum at the posterior (molar) region and increases gradually toward the anterior. 3. There is no significant difference in the width of the neutral zone in patients with prominent or flat alveolar ridges. 4. The width of the neutral zone increases as the vertical dimension of occlusion increases and decreases as the vertical dimension of occlusion decreases.