Comparative Analysis of Irrigation Techniques for Cleaning Efficiency in Isthmus Structures

Abstract

Introduction: This study aimed to evaluate the removal of a biofilm-mimicking hydrogel from isthmus structures in a simulated complex root canal system consisting of 2 curved root canals by Laser-activated irrigation (LAI, AdvErl Evo, Morita) and mechanical activation techniques.

Methods: A 3D-printed root canal model with 2 parallel root canals (60°-curvature, radius 5 mm, dimension 25/.06) with a total length of 20 mm connected via isthmuses (2.5 × 0.4 × 0.2 mm) at 5 mm and 8 mm from the apical endpoint and with lateral canals (diameter 0.2 mm) in all directions at 2, 5, and 8 mm from the apex was filled with a colored biofilm-mimicking hydrogel. Irrigation protocols under continuous irrigation with distilled water (3 × 20s per root canal; 3 ml/20s; n = 20) included conventional needle irrigation (=NI); manual agitation (=MA, gutta-percha point 25/.06); EndoActivator (=SAI-EA, 25/.04); EDDY (=SAI-E, 25/.04); ultrasonically-activated irrigation (=UAI) and LAI (Er:YAG-laser; P400FL tip at canal entrance; 25pps, 50 mJ, 300μs). Removal of the hydrogel was determined as a percentage via standardized photos through a microscope. Statistical analysis was performed using Kruskal-Wallis and Conover tests (P = .05).

Results: Laser-activated irrigation (LAI) was associated with the greatest removal of hydrogel from the entire root canal system (P < .05), followed by SAI-E. No significant differences were reported for the coronal isthmus between LAI, SAI-E, NI, and MA (P > .05), but inferior results for SAI-EA and UAI (P < .05). In the apical isthmus, all techniques outperformed UAI (P < .05), with LAI, SAI-E, and NI showing the best results (P < .05).

Conclusions: Laser-activated irrigation (LAI) was superior to other irrigation techniques in the entire root canal system. SAI-E and NI performed comparable to LAI in the isthmuses.

Keywords: Biofilm; closed model; isthmus model; laser-activated irrigation; sonic activation; ultrasonic activation.