Effects of premolar extractions on Bolton overall ratios and tooth-size discrepancies in a north Indian population

AIM: The purpose of this study was to evaluate the Bolton overall ratio in a north Indian population reporting for orthodontic treatment and to determine the effect of extractions on the Bolton ratios. Another aim of the study was to check the effects of different extraction patterns on the final Bolton ratio. MATERIALS AND METHODS: One hundred and twenty pre-treatment dental casts (60 males and 60 females) of orthodontic patients were selected randomly. Mesio-distal dimensions of the mandibular and maxillary teeth were measured before treatment, and subjected to Bolton analysis. Hypothetical tooth extraction by the following combinations: All the first premolars, all the second premolars, upper first and lower second premolars and upper second and lower first premolars were performed for each patient. The measurement results were again subjected to Bolton analysis to see whether any tooth-size discrepancy had been created. RESULTS AND CONCLUSION: The tooth material ratio of the studied north Indian population shows a mild maxillary tooth material excess. Extraction of premolars in any combination causes the maxillary tooth material to further increase. There is no significant sex difference in the tooth material ratios with or without extractions. In patients requiring extraction; all first premolar extraction or maxillary first and mandibular second premolar extraction should be preferred. For deciding a treatment plan involving extraction of teeth, we need to consider that the maxillary tooth mass may increase after extraction. Furthermore, the normal or the clinically significant tooth size discrepancies may change following extraction of teeth.