The Prevalence of Intermaxillary Tooth Size Discrepancies

Abstract

The purpose of this study was to determine the percentage of patients with malocclusions who have intermaxillary tooth size discrepancies. After a range of acceptable anterior and first molar to first molar intermaxillary tooth size ratios was obtained from an analysis of 30 excellent occlusions, the mesiodistal tooth size from first molar to first molar of 100 patients with malocclusions (43 class I, 42 class II, 15 class III) was measured. Of the total sample, 43% had an anterior intermaxillary discrepancy and 12% had a first molar to first molar intermaxillary tooth size discrepancy. Regarding the anterior ratio, 81% of patients with discrepancies (35% of the total sample) had maxillary teeth which were too small or mandibular teeth which were too large and 19% of those with discrepancies (8% of the sample) had maxillary teeth which were too large or mandibular teeth which were too small. Regarding the first molar to first molar ratio, 75% of patients with discrepancies (9% of the total sample) had maxillary teeth which were too small or mandibular teeth which were too large and 25% of those with discrepancies (3% of the total sample) had maxillary teeth which were too large or mandibular teeth which were too small. Separate calculations for patients with class I, class II and class III malocclusions showed discrepancies in anterior intermaxillary tooth size ratio in 49% of class I patients, 29% of class II, and 53% of class III. There were 14% of both class I and class II groups, and 7% of class III. Since many patients who seek orthodontic correction of their malocclusion will have intermaxillary tooth size discrepancies, orthodontists should routinely investigate the possibility of such discrepancies.