Anatomical features of the teeth should be accounted for dental treatment plans. The need for constant monitoring of changes in the dentition system determines the relevance of this research. The study aimed to establish the size of anterior teeth with the help of odontometry. We made bi-layer single stage impressions and cast diagnostic models of the anterior teeth of 50 male and 50 female participants aged 18–24 years. The absolute sizes of crowns of incisors and canines were established. To assess the reduction of lateral incisors, we calculated the interincisor index (Ii) of teeth 22 and 21; sexual dimorphism was determined using the Garn–Lewis formula. It was discovered that there are no differences in the mesiodistal widths of crowns of contralateral teeth on the right and left sides (p > 0.05). The mesiodistal width of crowns of anterior teeth decreases (significant changes) in the following order: maxillary central incisors → maxillary canines → mandibular canines and maxillary lateral incisors → mandibular lateral incisors → mandibular central incisors. The degree of reduction of lateral incisors is low (Ii = 74.9) and more prominent in males than in females. In the examined patients, the greatest mean length of crowns of anterior teeth is that of upper central incisors and lower canines, while upper canines are shorter in length and upper lateral incisors, lower central and lateral incisors have the shortest mean crown length. Males have longer (mean length) crowns of lower canines, upper incisors and canines than females, the difference being significant (p < 0.001). The parameters of the crowns determined in this study showed that they have sufficient height and mesiodistal width, which, together with the low degree of reduction of the lateral incisors, justifies the possibility of direct fabrication of orthodontic fixed retainers. The data can also be used at the stage of dental treatment planning.