Background: The aim of this study was to investigate the factors that associate the decayed, missing due to caries, and filled teeth (DMFT) index of patients with dental anxiety during dental treatment discontinuation. Methods: A total of 110 patients who complained of fear and anxiety toward dental treatments and who re-visited following treatment discontinuation were enrolled in the study. Patient and dental data considered to be related to caries were digitally collected from medical and dental records. The decayed (D), missing (M), and filled (F) scores, and the DMFT index before and after discontinuation were compared using Wilcoxon signed-rank tests, and the associated factors were evaluated using the Poisson and multiple regression analyses. Results: The D score and DMFT index augmented significantly during the discontinuation period, and the F score reduced. There was no significant change in the M score. The change in the D score was associated by the pre-discontinuation D score and the number of experiences of intravenous sedation, and the change in the F score was associated by the duration of treat-ment discontinuation, the DMFT index before discontinuation, and the number of experiences of intravenous sedation. The upsurge in the DMFT index was associated by the experience of intravenous sedation, the D and M scores, and the DMFT index before discontinuation. Conclusion: Discontinuation of dental treatment was proven to be associated with the incidence of caries in dentally-fearful patients.