Effect of Vehicles and Irrigation Solutions and Methods on Removal of Double Antibiotic Paste from Root Canals: Insights from High-performance Liquid Chromatography Analysis

Introduction: In regenerative endodontics, eradicating antibiotic residues from root canals is imperative, given their detrimental effects on human apical papilla stem cells. Previous antibiotic removal studies lacked precision in identifying types and quantities of residual antibiotics. High-performance liquid chromatography (HPLC) enhances sensitivity and specificity, enabling accurate detection and quantification of residual drugs. Using HPLC analysis, this study explored the influence of vehicles and irrigation solutions and methods on double antibiotic paste (DAP) removal from root canals. Methods: Two DAP formulations, each containing 5 mg/mL ciprofloxacin and metronidazole, were created using distinct vehicles: macrogol and propylene glycol (MP) or hydroxypropyl methylcellulose (HPMC). Subsequently, 5 mL of DAP was applied to 200 simulated immature teeth with open apices (n n = 100 per formulation) and cultured for 28 days at 37 degrees C. Samples were then divided into 11 groups (n n = 20 per group), and canals were irrigated with 17% ethylenediaminetetraacetic acid or 10% citric acid, employing a positive pressure syringe or passive ultrasonic irrigation. The irrigation solution and dentin sample from each tooth were evaluated via HPLC for ciprofloxacin and metronidazole quantification. Results: Citric acid exhibited significantly superior efficacy in antibiotic removal from root canals, with no observable effect of irrigation methods on drug removal. The HPMC-based DAP formulation significantly enhanced ciprofloxacin removal compared with MP-based DAP. Conclusions: For antibiotic paste removal from root canals, citric acid is effective, and HPMC is a preferable vehicle over MP. Overall, HPLC is a valuable method for detecting, removing, and quantifying residual antibiotics in root canals. (J Endod 2024;50:1307-1313.)