An in vitro Evaluation on a Novel Root Canal Cleansing Method by Using Nylon Fibers

Abstract

Despite traditional metal-based dental files, such as NiTi being demonstrated effective in root cleaning, the tooth structure is always damaged. Thus, to fulfill the need for a minimally invasive tool for contemporary endodontics and dentistry, the use of polymer fibers might provide a good option, as it is soft, fabricable, and disposable. In this study, two types of nylon fibers with respective average diameters of 206.9 µm (fiber W) and 156.4 µm (fiber B), respectively, were used as dental files, and mounted onto either a reciprocating or a low-speed rotary hand-piece. In vitro, simulated root canal models were colored red using nail varnish, and then cleaned by the fiber files mounted on the hand-pieces. Three parts of the simulated models, i.e., the apical third, the medium third, and the coronal third, were chosen to assess the cleaning the efficiency (CE) of each specimen by calculating the ratio of the cross-sectional area changes, before and after cleansing, using micro-Computer Tomography (CT). A NiTi file with a low-speed hand-piece was used as a control. SEM was used to observe the nylon fiber surfaces before and after the cleansing. Micro-CT results showed that for both the nylon fibers, W and B, an average CE of 82.11% ± 9.68% for the medium third could be achieved, which is statistically higher (p < 0.01) than the coronal third and apical third. The cleansing efficiency was not affected by, the types of fibers, nor the hand-pieces according to student’s t-test. Most of the nylon fibers could withstand deformation after the cleansing. To conclude, nylon fiber files have demonstrated a certain cleansing efficiency in simulated root canals, and micro-CT is a promising method to assess CE.