Abstract
The main goal in comprehensive orthodontic treatment is to obtain an optimal functional occlusion, overbite and overjet. Tooth size discrepancies of the maxillary and the mandibular arches are an important factor for achieving this goal. Inadequate relationships between the maxillary and the mandibular teeth can pose problems in achieving the ideal occlusion. Early treatment planning and proper diagnosis of tooth size discrepancy minimizes problems attained at finishing stage. Bolton’s ratios set an ideal relationship of maxillary tooth width to mandibular tooth width. This article shows the significance, validity as a diagnostic tool and the methods of measuring tooth size discrepancy.