Background <p>Oral health is strongly related to diet, and pro-inflammatory dietary patterns may worsen dental diseases through systemic inflammation. This study examined the relationship between the Food-based Dietary Inflammatory Index (FDII) and dental health, assessed by the DMFT index (Decayed, Missing, and Filled Teeth index), in Iranian adults.</p> Method <p>This cross-sectional study analyzed baseline data from the Bandare-Kong cohort, a subset of the prospective PERSIAN study, including 3,630 Iranian adults aged 35–75 years. Dietary intake was assessed using a validated food frequency questionnaire, and FDII was used to assess the inflammatory potential of participants ‘dietary patterns. Participants were classified into tertiles based on their E-FDII scores. The DMFT index was calculated as the sum of decayed, missing (due to caries), and filled permanent teeth. Generalized linear regression models (GLR) were used to examine the association between FDII scores and dental health outcomes.</p> Results <p>In the total population, higher dietary inflammatory potential was suggestively associated with poorer oral health. Compared with T1, T2 and T3 of E-FDII were related to fewer teeth [β = − 0.9 (–1.2 to − 0.6) and − 1.0 (–1.5 to − 0.8)], a higher number of decayed teeth [0.3 (0.1 to 0.5) and 0.4 (0.2 to 0.8)], more missing teeth [0.9 (0.6 to 1.3) and 1.1 (0.8 to 1.4)], and higher DMFT scores [1.1 (0.6 to 1.5) and 1.5 (1.0 to 1.9), p-trend = 0.001] in the adjusted model, while the number of filled teeth showed no clear association. Stratified analyses indicated that these suggestive trends were more apparent in women and middle-aged adults.</p> Conclusion <p>Our findings indicate that higher diet-related inflammatory potential is associated with poorer dental health in a representative sample of Iranian adults. Given the small effect sizes, the clinical relevance may be limited. Longitudinal studies are warranted to clarify the temporal relationship and underlying mechanisms.</p>