Analysis of Bolton Ratios in Skeletal Class I Malocclusion and Effects of Various Four-Premolar Extraction Combinations Before and After Treatment

Abstract

This study was conducted to find whether different premolar extraction patterns lead to a change in the Overall Bolton ratio from 0.91 and the Posterior Bolton ratio from 1.05, among the Pakistani population in a skeletal class I malocclusion. This quasi-experimental study took place in Khyber College Of Dentistry, Peshawar. Dental plaster models of the patients with skeletal class 1 malocclusion were collected. A Digital Vernier Caliper was used to calculate the Bolton's ratios. The Bolton ratios were again calculated after hypothetical extractions of all the 1st premolars (4/4), all 5s, upper 4s and lower 5s, and upper 5s and lower 4s. The sample consisted of 12 males and 18 females. The change in Overall Bolton ratios was statistically significant for 4s extractions. For the Posterior Bolton ratio, the 4/4 and 4/5 extraction patterns were significant. Taking out the premolar teeth leads to a statistically significant but clinically insignificant reduction in the Posterior and Overall Bolton ratios in Skeletal class I malocclusion.