Influence of final irrigation protocol after photodynamic therapy on the depth of sealer penetration – A confocal laser scanning microscopy study

Aim: Evaluates the depth of sealer penetration into dentinal tubule with photodynamic therapy (PDT) and sonic activation of irrigants. Methods: Sixty extracted single-rooted mandibular premolar human teeth were decoronated and biomechanical preparation was done till F3. The samples were randomly divided into six groups (n = 10) according to the final irrigation protocol. Group 1: Sodium hypochloride (NaOCl)-root canals irrigated with 3% NaOCl for 1 min and the root canals are flushed with sterile saline. Group 2: (PDT + NaOCl)-PDT followed by NaOCl irrigation for 1 min, then final flush by sterile saline. Group 3: Etidronic acid (HEBP)-root canals irrigated with Twin Kleen for 1 min. Group 4: (HEBP + SONIC)-root canals irrigated with Twin Kleen for 1 min and sonic activation for 30 s. Group 5:(PDT + HEBP + SONIC) – PDT followed root canals irrigated with Twin Kleen for 1 min and sonic activation for 30 s. Group 6: (PDT + HEBP) – PDT followed by final irrigation with Twin Kleen for 1 min. After the final irrigation regimen, the canals were obturated with Bioroot RCS sealer mixed with 0.1% rhodamine. The depth of sealer penetration was measured using confocal scanning microscopy. Two-way ANOVA and Tukeys multiple post hoc test were used for statistical analysis. Results: Among six groups, HEBP + SONIC 749.55 (µm) and PDT + HEBP + SONIC (752.4 µm) showed higher depth of sealer penetration even in terms of coronal, middle, and apical sections compared to other groups, with mean difference 749.55 and 752.45, which were statistically significant, respectively (P < 0.05). Conclusion: The sonic activation of irrigant increases the sealer penetration and antimicrobial PDT showed limited interaction with the sealer penetration.