ABSTRACT This prospective, controlled, single-center clinical study aims to compare postoperative pain levels and analgesic consumption after nonsurgical endodontic retreatment in individuals with diabetes mellitus and systemically healthy individuals. In addition, the study aims to evaluate the relationship between HbA1c levels, type of antidiabetic medication, and postoperative pain within the diabetes mellitus group.

A total of 54 patients with single-rooted teeth requiring nonsurgical endodontic retreatment due to persistent endodontic problems following previous root canal treatment will be included. Participants will be allocated into two groups according to systemic status: a diabetes mellitus group and a systemically healthy control group, with 27 patients in each group.

All retreatment procedures will be performed by a single operator using a standardized clinical protocol. Previous root canal filling materials will be removed, root canals will be reshaped, irrigated according to a standardized irrigation protocol, and obturated using an epoxy resin-based root canal sealer and gutta-percha cones with the cold lateral condensation technique.

Postoperative pain will be assessed using a Visual Analog Scale at 6, 12, 24, and 48 hours after treatment and on postoperative days 3, 4, 5, 6, and 7. Analgesic consumption will be recorded at the same follow-up time points. Intergroup comparisons, changes in pain scores over time, and associations between HbA1c levels, antidiabetic medication type, and postoperative pain will be evaluated using appropriate statistical tests. The statistical significance level will be set at p < 0.05.

Inclusion Criteria:

Patients aged 18 to 60 years. Patients classified as medically healthy (ASA I) for the control group or as having diabetes mellitus (ASA II or ASA III) for the diabetes mellitus group.

Single-rooted, single-canal teeth with closed apices. Teeth with previous root canal treatment completed at least 4 years before enrollment.

Teeth with root canal filling ending 1 to 4 mm coronal to the radiographic apex.

Teeth diagnosed with asymptomatic apical periodontitis. Teeth with a periapical index score between 2 and 4. Teeth without pain on percussion or palpation. Teeth not requiring periodontal or prosthetic treatment. Teeth suitable for rubber dam isolation.

Exclusion Criteria:

Use of analgesics, antibiotics, or corticosteroids within the last 2 weeks before nonsurgical endodontic retreatment.

Teeth with periodontal attachment loss. Teeth with vertical root fracture, external root resorption, or perforation. Teeth with fractured prosthetic restorations. Non-restorable teeth. Patients with severe pain and/or acute apical abscess. Pregnant patients. Teeth with calcified root canals. Individuals considered unable to comply with treatment procedures because of intellectual disability, developmental delay, or advanced age.