(PR111) Ex Vivo Comparison of Various Irrigation Protocols in Smear Layer Removal

Objective(s): Smear layer removal (SLR) is a critical step in endodontic treatment. Triton, an all-in-one irrigant, purportedly achieves SLR with similar efficacy to ethylenediaminetetraacetic acid (EDTA) with sodium hypochlorite (NaOCl). Irrigation adjuncts including sonic and laser activation also enhance SLR. However, no study to date has evaluated Triton combined with laser activation for SLR. This study’s objective was to determine the most effective irrigant-adjunct combination for SLR.

Methods: 143 single canal roots were instrumented and randomly divided into eleven groups (n=13). One group received no irrigation (positive control). Four groups underwent passive needle irrigation (PNI) with Triton, EDTA, NaOCl, or EDTA/NaOCl. Six groups underwent sonic or laser activated irrigation with Triton or EDTA/NaOCl. SLR was assessed quantitatively with irrigant calcium ion concentrations ([Ca²⁺]) measured by inductively coupled plasma mass spectrometry and qualitatively with dentinal tubule scanning electron microscopy (SEM) scores. Fully adjusted linear and ordinal regression models were generated to compare [Ca²⁺] and SEM scores respectively. During both PNI and laser activated irrigation, the regression models demonstrated that EDTA/NaOCl collected significantly higher [Ca²⁺] than Triton (p < 0.03), and EDTA/NaOCl had 12.3 times the odds (p < 0.0001) for lower SEM scores while Triton had 3.4 times the odds (p < 0.01). Both lasers significantly increased [Ca²⁺] (p < 0.01) and increased the odds of having lower SEM scores (p < 0.05).

Conclusion: EDTA/NaOCl is more effective than Triton for SLR. Additionally, laser activation with either Er,Cr:YSGG or Er:YAG enhances SLR for both EDTA/NaOCl and Triton. Overall, EDTA/NaOCl combined with laser activation is the most effective irrigant-adjunct combination for SLR.