Evaluation of the disinfection of dental anesthetic cartridges

Objective: The aim of this study was to evaluate the contamination level of brand new dental anesthetic cartridges and the efficacy of disinfectants on surface of cartridges artificially contaminated with Staphylococcus aureus ATCC25923 (SA). Methods: The tests were conducted on 96 plastic cartridges (Lidostesina100/Dentsply) and 96 glass cartridges (Alphacaine100/DFL). The number of colonies forming units (cfu) was estimated rubbing sterile swabs (0.1 ml of 0.9% NaCl) on the surface of the cartridges (in triplicate) immediately, 4h, 8h and 15 days after the opening of their original packages. The swabs were immersed in 0.9 ml of 0.9% NaCl. The samples were sonicated, inoculated in blood agar, incubated at 37oC during 48h and the colonies were counted. The standardized method of disinfection was performed by rubbing gazes soaked with the following disinfectants: 2% glutaraldehyde (GLUTA), 70% alcohol (ALC), povidone iodine (PVI) and chlorhexidine (CHLO). Saline solution (CONT) and mechanical rubbing without any solution (GAZE) were used as controls. The number of cfu was estimated by using the same technique. Cartridges were also artificially contaminated by immersion in 25 mL bacterial suspension of SA (108ufc/ml). These cartridges were submitted to the same disinfectants. Results: No contamination was observed in both cartridges (glass or plastic) in any period evaluated. PVI and CHLO completely eliminated the SA counts (Kruskal-Wallis, p<005) on surface of cartridges artificially contaminated. ALC and GLUTA provided reasonably disinfection (95%). CONT and GAZE provided disinfection in 66.6% of contaminated cartridges. Conclusion: the number of microorganisms (bacteria and fungi) was insignificant in brand new cartridges, which remained uninfected after at least 15 days following package opening. In addition, rubbing gazes soaked with any disinfectant provided an efficient disinfection.