Corrosion Behaviors of Disinfectants on Dental Unit Waterlines

To investigate the corrosion behaviors and antibacterial effects of sodium hypochlorite(NaClO)and hydrogen peroxide silver ion(HPSI)disinfectants with different concentrations against dental unit waterlines and provide guidance and reference for the use of chemical disinfectants,polyurethane tubes were immersed in ultrapure water(control group),0.1%NaClO,0.5%NaClO,1.0%NaClO,2.5%HPSI,5.0%HPSI,and 10%HPSI solutions for 6,12,and 18 weeks.Contact angles and Fourier transform infrared spectra were detected.Surface morphologies were observed using scanning electron microscopy and antibacterial activity was evaluated using Gram-positive Staphylococcus aureus(S.aureus).The results showed that sodium hypochlorite and hydrogen peroxide silver ion disinfectants presented good antibacterial activity against S.aureus.However,sodium hypochlorite could cause serious damage to the water pipes where corrosion pits and cracks were observed,and increasing the concentration of sodium hypochlorite could accelerate the corrosion process.Hydrogen peroxide silver ion disinfectants had no obvious damage to the water pipes.Therefore,hydrogen peroxide silver ion disinfectants are recommended to use for controlling bacterial infection in dental unit waterlines which can reduce the damage to the water pipes.

Cross Contamination in Oral Health Care: A Potential Public Health Risk—The Phenomenon of Biological Fluid Backflow: An Experimental Study

In oral health care, the spread of harmful infectious agents from the oral cavity is a constant concern. The aim of this study was to evaluate the possibility of cross-contamination between patients due to the backflow of biological fluids and contaminated aerosols into the water tubes of rotating instruments (high-speed turbines). A second aim was to assess the dispersion of the aerosols generated in the medical environment and the risk of contamination for the dentist. Materials and methods: For safety reasons, we carried out an experimental study on two sheep heads purchased from a butcher to simulate periodontal treatment in the two oral cavities. The first cavity was artificially contaminated with the reference strain of Staphylococcus aureus to assess the transfer of this bacteria from one cavity to the other through the waterlines of the high-speed turbine used. Results: The study revealed a worrying risk of cross-contamination from contaminated aerosols flowing back through the dental turbine into the dental unit waterlines (33.33%) [p S. aureus and total heterotrophic bacteria (THB) were dispersed at varying distances from the oral cavity. In particular, the highest contamination levels were found within 0.3 m of the patient for S. aureus (M = 43.66, SD = 1) and THB (M = 45.59, SD = 5), with contamination levels decreasing at a distance of 1.5 m, respectively (M = 5.63, SD = 3.61;M = 8.09, SD = 7.01) [p ≤ 0.05]. Conclusions: Procedures should be implemented to limit the risk of cross-contamination during dental treatment. This can be achieved by strict adherence to hygiene and asepsis measures in the dental unit and medical devices, compliance with regulatory standards (e.g., ISO 15883 1-2), and the installation of anti-retraction valves in dental turbines, dental chair unit and suction systems to prevent backflow of contaminated biological fluids and aerosols.