EVALUATION OF TOOTH SIZE DISCREPANCY IN DIFFERENT MALOCCLUSION GROUPS

Abstract

Background: Orthodontic diagnosis and treatment planning requires the patient’s thorough history,extra and intra oral examination, analysis of diagnostic records comprising of orthodontic photographs,necessary radiographs and properly trimmed study casts. Tooth-size is the sum of mesio distal widths ofthe maxillary and mandibular teeth. For ideal occlusion, teeth in both arches should be proportional insize. If larger teeth in one jaw are occluded with smaller teeth in the other jaw, ideal occlusion is notachieved. Tooth size analysis was presented by Bolton in 1958. The ratio for anterior segment wasderived to be 77.2±0.22% and 91.3±0.26% for the whole arch. Methods: A quantitative study wascarried out at the Armed Forces Institute of Dentistry (AFID), Rawalpindi, Pakistan, a tertiary carefacility. Cross sectional data was gathered from the study casts of patients undergoing orthodontictreatment at AFID, after obtaining informed written consent from them. 135 out of 200 study casts werefiltered based upon the inclusion and exclusion criteria. ANB angle and witt’s appraisal were traced oncorresponding lateral cephalograms. The mesio distal widths of all maxillary and mandibular teeth fromright first molar to left first molar were calibrated with the use of a manual caliper. The readings werethen used to compute the anterior and total Bolton ratios. Results: Significantly higher mean anteriortooth ratios were found for Class II (p<0.01) patients. All other ratios were within close range ofBolton’s norms. Conclusions: Skeletal Class II patients showed a tendency towards higher mesiodistalwidths of teeth in the mandibular anterior region.Keywords: Interarch tooth size discrepancy, Bolton’s norms, Skeletal Class I, II and III