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Comparative analysis of laser and ultrasonic irrigation techniques for smear layer removal in endodontics
Muhammad Mahmoud Abaza1, Tarek Abdel Hamid Harhash2, Ahmed Abbas Zaky2
1Medical Laser Applications Department, National Institute of Enhanced Laser Sciences, Cairo University, Giza, Egypt. dr.m3.abaza@hotmail.com.
Objective:
This in vitro study compared the efficacy of Er, Cr: YSGG laser (2780 nm), diode laser (976 nm), passive ultrasonic irrigation (PUI), and conventional syringe-needle (CSN) irrigation in smear layer removal, evaluating irrigant chemistry and root canal level.
Methods:
160 single-rooted premolars were instrumented and divided into four irrigation groups (n = 40/group): Er, Cr: YSGG (25 mJ, 50 Hz, radial-firing tip), diode laser (Pulsed 50%, 1.5 W), PUI, and CSN (side-vented needle). Groups were subdivided by irrigant (NaOCl + EDTA, EDTA, NaOCl, saline; n = 10/subgroup). Activation involved four 15-second cycles. Smear layer was scored (1-5) via SEM by blinded evaluators. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (p ≤ 0.05).
Results:
Er, Cr: YSGG achieved the lowest scores (best cleaning) across all thirds, outperforming diode laser, PUI, and CSN. NaOCl + EDTA was the most effective irrigant (p < 0.05). Remarkably, saline with Er, Cr: YSGG surpassed NaOCl alone. Apical thirds showed consistently poorer removal.
Conclusion:
Er, Cr: YSGG laser activation with NaOCl + EDTA is the most effective protocol for smear layer removal. The powerful mechanical effects of Er, Cr: YSGG dominated when using saline. Diode laser activation also surpassed PUI.
