`Effect of adjunctive antimicrobial photodynamic therapy on periapical healing and IL-6 modulation in apical periodontitis: a pilot randomized controlled study

Apical periodontitis (AP) is characterized by elevated IL-6 levels and periapical bone resorption. Antimicrobial photodynamic therapy (aPDT) is a promising adjunct to sodium hypochlorite (NaOCl) in root canal disinfection. This pilot randomized controlled trial evaluated the effect of adjunctive aPDT on IL-6 modulation and periapical healing in AP. This 11-month, parallel two-arm pilot randomized controlled study was conducted in a tertiary care hospital in North India (February–December 2024). Participants of AP, aged 18–40 years with single-rooted teeth, were randomized (1:1) to Group A (NaOCl disinfection) or Group B (adjunctive aPDT). The primary outcome was change in IL-6 levels (serum, GCF) from baseline to 6 months. Secondary outcomes were symptom resolution and radiographic healing (CBCT-PAI). Of 44 patients screened, 34 were randomized (17 per group). Two participants in the aPDT group were lost to follow-up. At 6 months, change in IL-6 levels was similar in serum (–0.09 ± 0.71 pg/ml vs. − 0.11 ± 0.70 pg/ml; p = 0.230) and GCF (0.01 ± 0.01 vs. − 0.01 ± 0.06 pg/ml; p = 0.551). Median CBCT-PAI scores were lower in the aPDT group [4 (3–5) vs. 3 (2–4); p = 0.014], with significance maintained on ITT analysis (p = 0.045). Both groups showed comparable symptom resolution. Adjunctive aPDT was comparable to NaOCl alone for IL-6 modulation and symptom relief but demonstrated superior radiographic healing. As a pilot trial, these findings provide preliminary evidence; larger definitive studies are warranted. Trial registration: Clinical Trials Registry-India identifier: CTRI/2024/02/062262.