Objective Our aim in this study was to examine the effect of chronotype differences and night eating syndrome on dental health parameters such as the decay-missing-filled teeth (DMFT) index, the severity of the periodontal disease and the number of endodontically treated teeth in patients admitted to the dental clinic. Methods The participants, 210 patients, filled out a package of psychological tools, including the Morningness-Eveningness Questionnaire (MEQ), the Night Eating Questionnaire (NEQ) and the Insomnia Severity Index (ISI). Afterwards, the DMFT index scores, the severity of the periodontal disease and the number of endodontically treated teeth of patients were recorded simultaneously with a routine dental examination. Results Findings show that the ISI and NEQ scores were significantly higher in the evening-type individuals (E-types) than in the morning-type individuals, and there was no significant difference between the chronotypes in terms of the number of endodontically treated teeth and the DMFT scores. In ordinal regression analyses, not brushing teeth (OR 7.94, CI 6.40-9.85), increased number of decayed teeth (OR 1.16, CI 1.13-1.19) and decreased MEQ scores (OR 0.95, CI 0.94-0.95) were statistically significant predictors for periodontal disease. Conclusion Although there was no correlation between chronotype differences and the DMFT index, and the number of endodontically treated teeth, E-types had a higher risk of periodontal disease severity.