A population-based survey on interarch malocclusion and background determinants.

Background: Genetics, environment, and ethnic factors are major contributors to the prevalence and variations of malocclusion.

Aim: The aim of study was to determine the prevalence of interarch problems in school-aged children, 9 - 11 years, living in Tehran; and to describe the role of ethnicity, education, and economic status on them.

Methods: The present data were part of the Comprehensive Evaluation of Skeleto-Dental Anomalies (CESDA) study conducted in 2015 among children living in Tehran, Iran. Cluster random sampling was applied among 19 districts of Tehran. A total of 38 schools were selected, and out of 1585 participants, the data of 1429 children were collected (response rate = 90%). The Chi-square test and binary logistic regression analysis were used for statistical analyses.

Results: Of all participants, 758 were boys and 671 were girls. The mean age was 121 ± 8 months. The most significant background determinants associated with molar relationship were ethnicity and place of residence. Class I right molar relationship was seen in 57.9% of the children and was generally more frequent in boys. Normal overjet was observed in 47.1%; 41.5% had an increased overjet, 16.2% had an anteroposterior cross-bite, and 11.8% had a lateral cross-bite. Midline discrepancy was seen among 61.1% of the children. Ideal anteroposterior, vertical, and horizontal relationship were observed in 31%, 53%, and 34% of the children, respectively. Only 10% of the children aged 9 - 11 years old had an ideal interarch relationship. Gender and place of residence had persistently significant association with having an ideal anteroposterior, vertical, horizontal, and interarch relationships (P < 0.002) in all four binary logistic regression models.

Conclusions: The majority of the children aged 9 - 11 years old have at least one interarch problem, although it is commonly preventable.

Relevance for patients: Early detection of children's orthodontic problems may help with effective prevention of further advanced anomalies.