Evaluation of the sterility of new reciprocating endodontic files through microbiological culture

Sterility information on reciprocating endodontic instruments is often unclear on the packaging. This can make clinicians uncertain about the safe use of these instruments without prior sterilization. This study evaluated the sterility of different reciprocating file systems directly from their original packaging. Six instruments from five commercially available reciprocating systems (Reciproc® Blue, WaveOne® Gold, W File, X1 Blue MK Life, and AllPrime R Blue) were tested. Each file was aseptically removed from its packaging inside a laminar flow chamber and immediately placed into sterile glass vials containing 5 mL of Brain Heart Infusion (BHI) medium. A 0.25 mL aliquot from each vial was collected after 24, 48, and 72 hours of incubation and plated onto Petri dishes. Then, they were incubated for an additional 72 hours. To ensure methodological reliability, two instruments (one Reciproc® Blue and one AllPrime R Blue) were deliberately contaminated with Enterococcus faecalis and served as positive controls. The presence of colony-forming units (CFUs) was assessed at 24-hour intervals throughout the experimental period. No bacterial growth was detected in any of the test groups at any time point, while CFUs consistently appeared in the positive controls. Considering the limitations of this study, reciprocating endodontic files, in their original manufacturer-sealed packaging and without prior clinical use, seem free of microbial contamination and are safe for immediate clinical application.