A new calibration procedure for expectation of arch length

Abstract EN

Background : the aim of the current study was to determine the relationship between arch length and different arch widths, and the possibility of using different arch widths as predictors for expectation of arch length in upper and lower dental arches and in both genders.

The current study is a first attempt to select the patients on the basis of gender 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 untreated Iraqi adult subjects (60 male and 60 females) aged 17-27 years old.

The dental study casts of both upper and lower dental arches were scanned and digitized by special procedure, six inter-arch widths and the arch length were traced 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 dental arches, regarding the inter-relation between upper and lower dental arches, there were significant correlation coefficients at 0.01 level for the different arch widths and length, the predictability of the relationship between the arch length and the inter-central incisor width in the upper arch was found to be very strong, while in the lower arch the predictability of the relationship between the arch length and the inter-central incisor width was also found to be very strong, but it was just found to be strong between the lower arch length and the lower inter-first premolar width.

Conclusions : the manner of strong correlation between different arch widths and length may be due to that the dental arch variables are acting together as a single biological unit, rather than a collection of discrete entities.

From the stepwise multiple linear regression analysis, it can be concluded that the upper inter-central incisor width plays an important role in the prediction of the upper dental arch length, while in the lower arch, the lower inter-central incisor and inter-first premolar widths play the same important role in the prediction of the lower dental arch length.