Individual anatomical variability of dental arches in the period of mixed dentition with optimal occlusal ratios

Abstract

Based on the results of a biometric study of plaster models of the jaws obtained in 84 children in the period of mixed dentition (8–12 years old) with a neutral location of the first permanent molars and optimal incisal overlap corresponding to the optimal functional occlusion of this age category, the main linear and angular parameters of the dental arches were determined with taking into account the trusive position of the incisors. Patients, taking into account the size of the inter-incisal angle, were divided into three groups. The first group (n=33) consisted of children with a mesotrusion position of the incisors (the value of the inter-incisor angle was 125–140°), the second group (n=27) consisted of children whose incisors were located protrusive (the value of the inter-incisor angle was less than 125°), the third group (n=24) – children with retrusion position of the incisors (the value of the inter-incisal angle is more than 140°). It has been established that in the period of mixed dentition, the main linear morphometric parameters of the dental arches are determined by the trusive types of the dental system and the vestibular-lingual inclination of the incisors. A diagnostically significant characteristic of the conjugation of the shape and size of the dental arches in the period of mixed dentition is the dental-diagonal coefficient, as the ratio of the length of the dental arch to the total component of the incisor-molar diagonals, the value of which for all types of dental systems is: for the upper jaw – 1.06 ± 0 .01; for the lower jaw – 1.09±0.01. It has been proven that in the period of mixed dentition the value of the incisal angle of the pentagon formed by the incisal diagonal and the width between the incisors is the smallest in children with protrusive incisors, while the parameters of the canine angle of the pentagon formed by the canine diagonal and the intercanine width are the largest in children with retrusion position of the incisors.