Effect of increased sodium hypochlorite irrigation time on sealer penetration: a CLSM study

Aim: The major objective of root canal treatment is to preserve severely damaged or carious teeth through effective disinfection and obturation. The chemomechanical preparation with irrigation is critical. Sodium Hypochlorite is considered the gold standard for root canal irrigation due to its antimicrobial action and organic tissue dissolution. Methods: Sixty extracted human mandibular premolars were instrumented and randomly allocated into three groups (n=20) based on final irrigation, which was performed using 3% NaOCl with passive ultrasonic irrigation (PUI): Group 1: 3 minutes, single activation. Group 2: 6 minutes, two activations. Group 3: 12 minutes four activations. Rhodamine B-labeled sealer was used for obturation. Teeth were sectioned horizontally at 2, 5, and 7 mm from the apex and analysed using confocal laser scanning microscope. Results: The results demonstrated a significant increase in both percentage and depth of sealer penetration coronally, with maximum values at 7 mm and minimum at 2 mm levels (P < 0.05). Groups 2 and 3 exhibited significantly greater penetration compared to Group 1 at all levels. There was a statistically significant difference in the percentage of sealer penetration at the 2mm and 5mm level between Group 2 and Group 3. Conclusions: Increasing the irrigation time of NaOCl during the procedures with continuous replenishment helps in better penetration of sealer into the dentinal tubules, thus improving the efficacy of root canal obturation.