Determination of the Dental Arch Form in the Primary Dentition Using a Polynomial Equation Model.

Purpose: Many geometric forms and mathematical functions have been proposed as models of the dental arch; however, no such information seems to be available for the primary dentition. The purpose of this study was to develop a model for dental arch form in the primary dentition. Methods: The participants were 92 children (47 boys, 45 girls) in primary dentition. Dental casts were used to measure dental arch dimensions with digital calipers. The arch form was classified as round, long, and short. The values of A and B in the polynomial function formula Y=Axm+Bxn were calculated so that the curve would pass through all teeth in the arch. Data were analyzed and compared with the independent t-test and multiple regression analysis. Results: There was significant difference between boys and girls in dental arch widths (P=0.025) and depths at mandibular primary canines (P<0.001) but not significant at the maxillary primary canines (P>.05). The width and depth of the arches at the primary canines correlated significantly with the width and depth at the primary molars (P<0.001). Conclusions: The sixth-order polynomial function Y=Ax6+Bx² is a potentially accurate mathematical model of arch form for primary dentition. [ABSTRACT FROM AUTHOR]