A new calibration procedure for expectation of arch length

Abstract

Background: The aim of the current study was to determine the relationship between arch length and different archwidths, and the possibility of using different arch widths as predictors for expectation of arch length in upper andlower dental arches and in both genders. The current study is a first attempt to select the patients on the basis ofgender in regard to different dental arch widths and length.Subjects and method: The sampling procedure comprised 120 pairs of upper and lower dental casts of untreatedIraqi adult subjects (60 male and 60 females) aged 17 -27 years old. The dental study casts of both upper and lowerdental arches were scanned and digitized by special procedure, six inter-arch widths and the arch length weretraced on images of upper and lower dental arches by the digitization procedure.Results: Student′s t-test showed no marked gender differences for all measurements in both upper and lower dentalarches, regarding the inter-relation between upper and lower dental arches, there were significant correlationcoefficients at 0.01 level for the different arch widths and length, the predictability of the relationship between thearch length and the inter-central incisor width in the upper arch was found to be very strong, while in the lower archthe predictability of the relationship between the arch length and the inter-central incisor width was also found tobe very strong, but it was just found to be strong between the lower arch length and the lower inter-first premolarwidth.Conclusions: The manner of strong correlation between different arch widths and length may be due to that thedental arch variables are acting together as a single biological unit, rather than a collection of discrete entities. Fromthe stepwise multiple linear regression analysis, it can be concluded that the upper inter-central incisor width plays animportant role in the prediction of the upper dental arch length, while in the lower arch, the lower inter-centralincisor and inter-first premolar widths play the same important role in the prediction of the lower dental arch length