Dental caries experience in first permanent molars and its associated factors among Iranian primary school-aged children: a cross-sectional study

Abstract

Abstract Background Dental caries in first permanent molars is a highly prevalent condition in primary school-aged children and represents a substantial oral health burden in Iran. This study aimed to assess dental caries experience, based on the decayed, missing, and filled teeth index (DMFT) and its components in the first permanent molars, and to identify its associated factors among primary school-aged children in Hamadan, Iran. Methods A cross-sectional study was conducted among 2,920 primary school students aged 7–12 years in Hamadan, Iran, between November 2019 and January 2020. Participants were selected through a three-stage cluster sampling method, in which schools and classes were randomly chosen, and all eligible students in the selected classes were included. Dental examinations were performed by a single calibrated dentist under natural light, using a World Health Organization (WHO) probe and disposable mirror, following the WHO criteria. Data on students’ age, sex, residential area, history of dental pain in the past year, parental supervision, and oral health behaviors were collected using a structured interviewer-administered questionnaire, while information on parents’ education and occupation was obtained from school records. Data were analyzed using Stata version 14.0 (StataCorp LP). Caries experience in first permanent molars was defined as a binary outcome (DMFT > 0 vs. DMFT = 0), and associations with sociodemographic and oral health behavioral factors were examined using multiple logistic regression. A p-value < 0.05 was considered statistically significant. Results The mean (SD) age of participants was 9.45 (1.71) years; 2,920 students were included (response rate 86.8%). The overall mean (SD) DMFT for first permanent molars was 1.56 (1.51), and the highest mean DMFT was observed at age 12 (mean 2.17, SD 1.50). The proportion of decayed first permanent molars decreased with age, from 90.44% at age 7 to 81.60% at age 12. In multiple logistic regression, where caries experience in first permanent molars was defined as DMFT > 0, age, sex, residential area, recent dental pain, and father’s education and occupation were independently associated with the odds of caries experience. The odds of caries experience increased with age (OR = 1.56, 95% CI [1.49–1.65], p< 0.001) and were higher in girls than in boys (OR = 1.42, 95% CI [1.21–1.67], p< 0.001). Children whose fathers had lower education had higher odds of caries experience (OR = 1.55, 95% CI [1.22–1.97], p < 0.001), and those living in lower socioeconomic residential areas also had increased odds (OR = 1.25, 95% CI [1.00–1.55], p = 0.04). Conclusion The high proportion of decayed first permanent molars reflects a considerable burden of dental caries among primary school children in Hamadan. Higher DMFT was associated with age, female sex, and lower paternal education, underscoring the need for targeted preventive programs.