Aim: The purpose of the present study is to evaluate the effectiveness of different irrigation techniques EndoVac, RinsEndo, Canal CleanMax (CCMax), SonicMax, Passive Ultrasonic Irrigation (PUI), and Manual Needle Irrigation (MNI) on dentin erosion and smear layer removal using Scanning electron microscopy (SEM).

Materials and methods: Seventy extracted single-rooted teeth were instrumented with ProTaper rotary instruments. The roots were randomly divided into six experimental groups (n = 10): EndoVac, RinsEndo, CCMax, SonicMax, PUI, and MNI. Final irrigation was performed with NaOCl followed by ethylenediaminetetraacetic acid and NaOCl. Six roots served as control and were irrigated with only NaOCl. Next, the roots were sectioned in a buccolingual direction and the halves were examined by SEM. Smear layer and erosion scores were recorded in the cervical, middle and apical third of the roots. Data analysis was performed using the Kruskal-Wallis and Mann-Whitney U-tests with a level of significance α = 0.05.

Results: PUI had the greatest amount of smear layer compared to other groups (P < 0.001). However, SonicMax had the greatest degree of erosion compared to RinsEndo, MNI, PUI, and EndoVac groups (P < 0.001) and CCMax group (P < 0.05).

Conclusions: RinsEndo and EndoVac techniques left the least amount of smear layer while causing erosion the least compared to CCMax, PUI, and MNI techniques.