Assessment of the Sterility of New Endodontic Files Received From the Manufacturer Using Microbial Culture and Scanning Electron Microscopic Analysis: An In Vitro Study.

Background As endodontic hand files are essential tools for root canal instrumentation and treatment, these instruments have been a constant source of debate regarding whether to reuse them or use them just once. The aim of this in vitro study is to evaluate the sterility of five brands' new endodontic files received from manufacturers without sterilization before clinical use via microbial culture (bacteria and fungi) and bioburden using scanning electron microscopic (SEM) analysis. Methodology This study included 25 K-type hand files with equal numbers from five brand groups (n=5; groups 1 to 5), named Tia Dent, Prevalent, Mani, Thomas, and Dentsply, respectively. The new files were exposed to microbial culture prior to clinical use and SEM analyses. A Fisher's exact test was performed to compare the differences in contamination among the five tested groups. Results In the SEM, all the five brand groups showed one contaminated file out of five files (20%). Fisher's exact test findings revealed statistically significant variations between the five brand groups, as nine out of 25 (36%) files of the tested groups had positive contamination in the microbial culture experiment. Bacterial contamination was present in three (60%) of the five Tia Dent group files, four (80%) in the Prevalent group files, and two (40%) in the Mani group files. Those with fungal contamination were one (33%) in the Tia Dent group and one (25%) in the Prevalent group (P=0.027). The bacterial culture showed that 100% of the new K-files tested negative in both the Thomas and Dentsply groups. Conclusions This study concluded that there was a bioburden on new endodontic K-type hand files of different brand groups before sterilization or when immediately used.