Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 10 4 2018 12 01 Evaluation of the Relationship of the Permanent First Molar Enamel Defects And Dental Caries With Delivery Type and Birth Weight In 6- to 12-Year-Old Children in Hamadan 120 124 10.34172/ajdr.2018.24 EN Rezvan Rafatjou Bahar Ahmadi https://orcid.org/0000.0001.8091.5996 Mohammadmehdi Azizzadeh Journal Article 10.34172/ajdr.2018.24 2018 07 11 2018 11 10 Background: Enamel defects can negatively affect the appearance of the teeth, increase the tooth sensitivity, disrupt the occlusal function, and make the teeth susceptible to caries. The present study was carried out to investigate if the delivery type and birth weight have any effect on the prevalence of tooth caries and enamel defects among a population of children from Hamadan, Iran. Methods: This cross-sectional study was conducted on a total number of 182 children aged 6-12 years old born from 2006 to 2012. Studied variables were birth weight, birth height, head circumference, gestational age, gender, delivery type, birth order, duration of nocturnal feeding, and nutrition type up to two years old. Developmental defects of enamel index were used to determine the prevalence of enamel defects and decayed, missing, and filled teeth (DMFT) index to study dental caries. The results of tests were analyzed by SPSS software using t test, chi-square test, Fisher exact test, Mann-Whitney test, Kruskal-Wallis test and Pearson correlation coefficient. Results: The overall prevalence of enamel defects was obtained 15.38%. The prevalence was significantly associated with delivery type (P=0.05), while no significant association was found between enamel defects and birth weight (P=0.684). DMFT index was significantly related to birth weight and delivery type, while duration of nocturnal feeding was the only variable found to be significantly related to DMFT index. Conclusions: The cesarean section and low birth weight (LBW) may be associated with the developmental defects of enamel (DDE) and dental caries. Nocturnal feeding was another factor that may be associated with dental caries and DDE.