Influence of irrigation needle design on cleaning efficiency in 3D mandibular molar models

This study aimed to evaluate the effectiveness of various endodontic irrigation needles in removing residual tissue from root canals, focusing on the apical, middle, and coronal thirds. Forty 3D resin replicas of mandibular molars (n = 10/group) were divided into four distinct needle types: an open-ended needle, a closed-ended and lateral-vented needle, a closed-ended and double lateral-vented needle, and a polyethylene irriFlex needle with a double lateral outlets. A 30G NaviTip needle uniformly filled the canal system, delivering the artificial biofilm mixture formulated with a hydrogel. Then, the pre- and post-irrigation images were assessed quantitatively to measure tissue removal and qualitatively to determine the presence or absence of tissue remnants. The open-ended needle significantly (p < 0.05) removed tissue across the entire canal length. Open-ended and polyethylene irriFlex needles were more effective in the apical region than closed-ended needles (p < 0.05). Specifically, in the apical third, the percentages of remaining tissue were 23.7% for the open-ended and 26.8% for the irriFlex needle, compared to 53.9% and 44.9% for the closed-ended needles. The open-ended needle showed superior efficacy in the middle and coronal regions (p < 0.01). Qualitatively, only one sample was completely free of tissue in the entire root canal and one in the apical third. The open-ended needle demonstrated superior cleaning efficacy in the root canal, particularly in the middle and coronal regions, while the irriFlex needle performed better in the apical region than closed-ended needles. These results showed the importance of needle type in effective root canal irrigation. This study indicates that needle type significantly affects tissue removal in endodontic irrigation; open-ended and polyethylene needles are most effective in apical canals.