"Evaluation of Tooth Size Discrepancies among Different Malocclusion Groups In Sirte" -Libya

Abstract

Background: Orthodontic diagnosis and treatment planning requires the patient's history, extra and intra oral examination, analysis of diagnostic records comprising of orthodontic photographs, radiographs and study casts. Tooth-size is the sum of the mesio distal widths of the maxillary and mandibular teeth. For ideal occlusion, teeth in both arches should be proportional in size. Tooth size analysis was presented by Bolton in 1958. The ratio for anterior segment was derived to be 77.2±0.22% and 91.3±0.26% for the whole arch. Material And Methods: Cross sectional data was gathered from the study casts of patients undergoing orthodontic treatment. 115 out of 160 study casts were filtered based upon the inclusion and exclusion criteria. ANB angle and Witt's appraisal were traced on corresponding lateral cephalograms. The mesio distal widths of all maxillary and mandibular teeth from right first molar to left first molar were calibrated with the use of a manual caliper. The readings were then used to compute the anterior and total Bolton ratios. Results: Significantly higher mean anterior tooth ratios were found for Class II (p<0.01) patients. All other ratios were within close range of Bolton's norms. Conclusions: Skeletal Class II patients showed a tendency towards higher mesiodistal widths of teeth in the mandibular anterior region. Keywords: Bolton's norms, Interarch tooth size discrepancy, Skeletal Class I, II and III.