| Dental Comprehensive Unit (DCU) is one of the main equipments used in Dental diagnosis and treatment. Dental unit waterlines (DUWLs) is consist of a narrow and complex pore plastic hose connected to each other, and function is relatively complex:such as in the process of diagnosis and treatment for dental handpiece and 3-in-1 syringe provides irrigation water, for the patient provides mouthwash, provides cooling water for therapy of teeth with vital pulp, provide irrigation water for spittoon and other. Studies have shown that serious microbial contamination in DUWLs, the total number of colonies can be up to 106cfu/ml and a variety of pathogenic microorganisms such as Pseudomonas aeruginosa, legionella pneumophila, Escherichia coli, amoebae, fungi and others. They are in the form of planktonic and biofilm exists in DUWLs, with the rotation of the mobile phone sprays of water and 3-in-1 syringe into the patient’s mouth, and become potential risk factors of cross infection in dental clinics. However, since half a century, how to effectively monitor and control the pollution of DUWLs is still inconclusive, and lack of research on the biological safety of disinfection methods.Objective:This study working on monitoring and control bacterial contamination in DUWLs. through the study of the total number of colonies in different parts of sampling points of DCU, structure and form of biofilm, look for good operation, repeatability and stable monitoring method, and biological safety control method.Methods:1) Colony counting method was adopted for different parts in DUWLs in Stomatological Hospital of Jiangsu province for baseline monitoring. And bacterial biofilm was observed by laser scanning confocal microscope and scanning electron microscope.The identification and drug-sensitivity of the bacteria were tested by French bioMerieuxATB. In order to understand in DUWLs pollution status and the difficulties of pollution control.2) The ATP biological fluorescence technique was used to monitor the pollution of DUWLs, and parallel compared with bacteria with quantitative methods to evaluate its feasibility of monitor the pollution of DUWLs.3) The DUWLs were treated with ddH2O,3%hydrogen peroxide,0.3% hydrogen peroxide nanosilver (Sanosil),5.25% sodium hypochlorite and 0.12% chlorhexidine,respectively.To study disfection effects of different disinfectants in controlling the pollution of DUWLs.4) By CCK-8 assay of four different disinfectants:hydrogen peroxide silver ion disinfectant (Sanosil), sodium hypochlorite disinfectant, disinfectant of hydrogen peroxide, a 0.2% chlorhexidine in different concentrations in vitro on human oral mucosal epithelial cells cytotoxicity, compare of different disinfectant of biological safety.5) Through the design of a new independent water storage tank of DCU, it may be achieved a conventient real-time dynamic disinfection function in DUWLs with low cost.Recults:1) In this study was found that the average colony number is 4.015* 103 CFU/ml and 13 kinds of conditional pathogenic bacteria was investigated in DUWLs which without regular disinfection. Thebiofilm which was thickness uneven, mixed a lot of cocci and rod bacteria was observed in thepipe wall of DUWLs2) High consistenty was observed in the results of ATP bioluminescence assay and colony counting method in traditional pollution of DUCLs (kappa=). ATP biological fluorescence technique can be used as a simple and rapid screening method in monitoring of dental unit water pollution.3) Four kinds of chemical disinfectants can effectively reduce water bacterial content and kill pathogens, but 0.3% hydrogen peroxide nanosilver (Sanosil) disinfection duration longer than other groups. Laser confocal microscopy observation showed hydrogen peroxide silver ion of biological membrane damage effect is better than the other three kinds of disinfectant (P< 0.05).4) The effect of four kinds of disinfectants on human mucosal epithelial cells under the common disinfection concentration can be produced after a certain period of time, but the hydrogen peroxide nanosilver (Sanosil) are relatively safe.Conclusion:There are serious microbial contamination in DUWLs, need to implement real-time monitoring, ATP bioluminescence method can be used as a quick and easy sieve method for water pollution monitoring of dental synthetic treatment. The complex structure ofDUWLs, the diversity of bacterial species and the existence of biological biofilm are the difficult points in infection control. The use of chemical disinfectant can obtain a better disinfection effect because it is be used planktonic bacteria and biofilm at the same time. However, the disinfection efficacy of different disinfectants is different, and the frequency of disinfection should be determined according to the characteristics of the disinfectants. The disinfection time of hydrogen peroxide nanosilver (Sanosil) disinfection is longer, and the damage ability of the biological membrane is larger, which is more suitable for the periodic disinfection. In addition, there is a biological safety problem of chemical disinfectant in common concentration, a certain time (>2h) contact may cause cell damage, in the use of special attention to the standardization of operation. |
PDF Full Text Request