Frequency and variability of nonmetric dental crown traits of primary and permanent molars in a group of orthodontic patients.

Abstract

Background: The present study aimed to assess the frequency and variation of 13 nonmetric dental crown traits (NDCT) in permanent and primary molars in German orthodontic patients.

Methods: Dental records from orthodontic patients were screened and evaluated. First and second permanent and primary upper and lower molars (from left and right sides) were assessed. Teeth with cavitated dental caries, occlusal wear, restorations and obvious dental deformities were not evaluated. The NDCT for permanent molars were identified and scored according to the odontoscopic system developed by Arizona State University Dental Anthropology System (ASUDAS). The NDCT for primary molars were identified and scored according to ASUDAS, Hanihara's method and Sciulli's method. The χ² test was used to investigate side preference and sexual dimorphism at a significance level of p ≤ 0.050.

Results: A total of 163 orthodontic patients (82 males and 81 females) aged 8-14 years were included. A sexual dimorphism was observed for the hypocone in first upper permanent molar (p = 0.041). The protostylid was observed in lower permanent molars (range 2.1-10%). Males presented more hypoconulid than females (p = 0.019). Only females presented the distal trigonid crest in lower first permanent molars (p = 0.002). The most common groove pattern in primary molars was Y; male presented more Y grade than females in the lower second primary molar (p = 0.039). Asymmetry was observed in some traits, ranging from 0 to 100%.

Conclusion: The present study showed the frequency of NDCT of molars in German orthodontic patients and demonstrated that some traits present sexual dimorphism.