An Investigation of Intermaxillary Tooth Mass Discrepancy: A New Approach

Abstract

This study investigated the incidence, amount, and location of intermaxillary tooth mass discrepancy in a sample of malocclusion cases. Obtaining accurate tooth measurements was a primary concern of the investigation. Interproximal separation was achieved in each case prior to the taking of a silicone rubber impression. Individual tooth dies were then produced from the impression and measured with direct reading instruments. A model of occlusion was adopted as a reference for evaluating tooth mass problems. Each case demonstrated some tooth mass discrepancy. The discrepancies in the posterior segments were generally very minor and of limited clinical significance. Larger discrepancies were found in the anterior segments. Most of these were small enough to be managed by clinical manipulation of tooth position, but approximately one-fifth were large enough to have significant effects on occlusion. The labia-lingual thickness of incisors was found to have considerable potential in affecting the anterior occlusion. Statistical analysis revealed no difference in the amount of tooth mass discrepancy between males and females. Likewise, there was no difference between Class I and Class II malocclusion groups. An anterior ratio and ''Anterior Percentage Relation" were calculated and they compared favorably with the results of the original investigators. The malocclusion cases had a wider range of values than those cases of excellent occlusion. Right-left tooth size asymmetry was investigated. The results indicated that the problem is not nearly as great as previously reported.