The position of the neutral zone in relation to the alveolar ridge.

Included in this study are 21 edentulous patients. They were classified according to their period of edentulousness into two groups. One group was edentulous from 1/2 to 2 years. The other group was edentulous for more than 2 years. The neutral zone (NZ) was located for each patient by using record bases, and an impression compound as the occlusion rim. A 30-gauge stainless steel wire was adapted along the center of the alveolar ridge on the final cast. A 24-gauge stainless steel wire was adapted and stabilized over the center of each occlusion rim. An occlusal view radiograph was obtained of each recording base and its cast. Each film was placed in a viewing box and the relationship between the images of the two wires in the buccolingual direction was studied in the anterior, premolar, and molar regions on the left and right sides. Where the two images coincided a zero score was given. In the case of buccal location a plus scores was given, and where there was a lingual location of the (NZ), a minus score was given. All measures were taken in millimeters. Statistical analysis was performed between the two groups. The longer the period of edentulousness, the more buccally/lingually located was the NZ.