Objective: This study aims to determine the relationship between the DMFT (decayed, missing, filled) index in cancer patients with variables such as cancer type and treatment type.

Material and method: Cancer patients who were examined in the Okan University Faculty of Dentistry between 2021 2023 and underwent radiotherapy/chemotherapy (RT/CT) were detected retrospectively via system. Patients with a history of cancer; demographic information, type of cancer, time spent on treatment, type of treatment (RT/CT/RT+CT), and DMFT index determined. A control group was formed, and demographic information and DMFT index were noted. All results were analyzed using IBM SPSS, and p

Results: 102 individuals (33 males 69 females) with a history of cancer, mean age 56; the control group consisted of 110 individuals (61 males 49 females) with an average age of 50 years. The most common type of cancer was breast cancer (45%). There was no significant difference in D/M/F and DMFT index of cancer treatment types. The DMFT index determined a significant difference between healthy and cancer patients (p<0.05). While the incidence of caries did not show a significant difference between healthy and cancer patients, the number of missing and filled teeth showed a significant difference. The DMFT index has a significant relationship with age and time since treatment but is insignificant with cancer types.

Conclusion: Regardless of cancer history, types, and treatment modality, it has a significant effect on the DMFT index.