Considering the high prevalence of dental caries in adults, it is necessary to study its risk factors to prevent the disease. Gastroesophageal reflux disease (GERD) is a common chronic disease with an increasing incidence that may affect the quality and quantity of saliva. This study aimed to determine the association of gastroesophageal reflux disease (GERD) with dental caries according to the DMFT index in the Azar cohort population. This cross-sectional study was performed on data obtained from the enrollment phase of the Azar Cohort Study (ACS), conducted on 15,000 adults aged 35 to 70. Data of 905 subjects with gastroesophageal reflux disease in the ACS-without full denture-together with a control group of 1894 subjects, who were matched in terms of gender and age, were included in this study. Dental caries data and data on GERD, demographic and socioeconomic characteristics, individual and nutritional habits, BMI, and toothbrushing frequency were elicited from the databank of the ACS center. A Generalized Linear Models assuming negative binomial distribution with a log-link function was used for analytical statistics to examine the effect of possible confounding variables. The DMFT index in the group with GERD was 15.09±6.18, and for the control group was 15.00±6.07. No statistical association was seen between GERD and dental caries. Among the variables included in the regression analysis, being younger and toothbrushing one or more times per day were associated with a lower DMFT index score. According to the results, having GERD did not increase the risk of dental caries. However, due to the cross-sectional design of the study, the results should be interpreted cautiously. The results showed that oral hygiene is one of the most influential factors in reducing dental caries prevalence.