The impact of different mechanical file systems with or without adjunctive approaches on disinfection of oval root canals: an ex vivo study.

Background The available evidence does not conclusively demonstrate the superiority of a specific file system for effectively disinfecting oval root canals. Additionally, it remains unclear whether adjunctive methods can enhance the disinfection of oval canals.Objectives The study aimed to compare bacterial reduction in oval canals using a single-file versus multi-file system, with or without adjunctive disinfection.Methods In total, 100 human maxillary second premolars with oval single-root canals were contaminated with Enterococcus faecalis biofilm. Teeth were divided into two groups: Reciproc Blue single-file and Hyflex CM multi-file. Each group had subgroups: saline irrigation, circumferential filing, sodium hypochlorite irrigation and ultrasonic activation. Bacterial sampling was done pre- and post-chemo-mechanical preparation. Results All instruments significantly reduced bacterial count but did not eliminate infection entirely. Hyflex CM showed higher bacterial reduction than Reciproc Blue, regardless of adjunctive approaches (p <0.001). Passive ultrasonic irrigation produced the most significant reduction.Conclusions Multi-file systems substantially reduced the bacterial load in the oval root canals compared to single-file systems. Adjunctive disinfection approaches improved the antibacterial effects of the different file systems employed during the basic chemo-mechanical preparation. Circumferential filing and passive ultrasonic agitation were effective adjunctive approaches in maximising the disinfection in oval root canals.