A new method for the measurement of Bolton discrepancy

Achieving a good functional occlusion with proper overjet and overbite requires that the maxillary and mandibular teeth be proportional in size. A bolton discrepancy will prevent the achievement of an ideal occlusion . Most of the orthodontists neglect to find this discrepancy before treatment because of saving time. Our aim in this study was to find which teeth create bolton discrepancy more and easier way to determine bolton discrepancy.172 pretreatment and 49 postreatment models were used in this study. Ideal Bolton Ratio(IBR) was determined from the 49 perfect occlusion identified by American Board of Orthodontics (ABO) dental grading system. The data were analyzed by Pearson correlation and paired sample t test.Ideal anterior ratio is 76,66± 2,19 and total ratio is 90,54± 1,71. The ratio between the total width of mandibuler second premolars and first molars, and the total width of maxillary central and lateral incisors showed greater correlation (r=0,73) with IBR. According to t test, there were differences between the right and left ratio, right and IBR, and left and IBR(p<0,05).Comparing the Bolton ratios calculated by cross quadrants (eg. Left lower to right upper) showed no statistical difference either with each other or IBR.Lower second premolars and molars, and upper four incisors can be used as predictors for determining Bolton discrepancy. Calculating Bolton ratio with cross quadrants may be an alternative and simpler way.