Evaluation of Cephalometric Standards for Zanjanian Population According to Downs' Analysis

 Following the morphological features of different races and ethnic groups, knowledge of standard dentofacial patterns of each ethnic group is essential. Therefore, this study aimed to explain cephalometric standards for the Zanjanian population according to Downs' analysis and compare them to Caucasian individuals.

 Seventy lateral cephalometries of Zanjanian adults (17 - 29 years old) who had been referred to a private orthodontic office in Zanjan, Iran with class I molar and canine relationship and normal overjet and overbite as well as minimum crowding/spacing/rotations were scanned and traced with the Novatech scanner and Dolphin software version 10. Next, statistical analyses were performed in order to compare the Zanjanian population to Caucasians.

 We found a significant difference between males and females in terms of interincisal angle, incisor-occlusal angle, incisor-mandibular plane angle, upper incisor proclination, facial angle, and angle of convexity.

 The analysis of six statistically significant parameters indicates that the upper and lower incisors in women of Zanjan were proclined and protruded compared with those of Caucasian subjects. Due to the statistical analysis on facial angle and angle of convexity, women also show more maxillary prognathism and skeletal class II pattern. Generally, a comparison of Zanjanian population cephalometrics based on Downs' analysis showed an increase in maxillary prognathism, maxillary and mandibular incisal protrusion and posterior rotation of the mandible.

 In conclusion, the Zanjanian population tends to have more dental and skeletal class II patterns than the Caucasians. In addition, gender comparison indicates lower and upper-incisors protrusion in women of Zanjan.