Bacterial Contamination of Endodontic Materials before and after Clinical Storage

Introduction: The aim of this study was to evaluate the bacterial contamination in endodontic consumables (gutta-percha points, rubber dams, paper mixing pads, caulking agents, and endodontic instrument sponges [EISs]) before and after clinical use and storage.

Methods: Materials were randomly sampled in triplicates at 3 time points (t₀, at package opening; t₁, at 7 days; and t₂, at 14 days) during their clinical usage. The gutta-percha points and caulking agent (25 mg) were added to 1 mL phosphate-buffered saline (PBS). The rubber dam, paper mixing pad, and EIS were added to 25 mL PBS. After vortexing, centrifuging, and removing the supernatant, the pellet was resuspended in 1 mL PBS, plated on fastidious anaerobic agar, and incubated aerobically and anaerobically. The grown colonies were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The total bacterial load was calculated in the remaining volume (800 μL) from each sample by quantitative polymerase chain reaction after DNA extraction.

Results: All tested materials showed a varied number of contaminated samples at the 3 time points (except EIS at t₀) using MALDI-TOF MS. The most isolated genera were Propionibacterium (42%) and Staphylococcus (32%). By using non-culture-based approaches, all tested materials at the 3 time points (except gutta-percha at t₀ and the caulking agent at t_0, t_1, and t₂) carried bacterial DNA.

Conclusions: The majority of the tested materials harbored bacteria in their samples before and after clinical storage. Nosocomial infection derived from commonly used consumables could have an impact on the outcome of endodontic treatment.