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Fungi present in Dental Unit Water (DUW) can pose a health hazard to patients and dental personnel. Yet, the issue of fungal contamination of DUW and their conduits, DUW Lines (DUWLs) has been poorly addressed despite a growing body of data on the subject. In this comprehensive review, we aim to address this gap by examining the diverse fungal contaminants found in DUW, the challenges associated with controlling their growth within waterline biofilms, and the various measures employed for fungal decontamination. The review underscores the intricate fungal ecosystems that exist within DUWLs and emphasizes the importance of implementing targeted antimicrobial strategies to uphold waterline hygiene. However, it is important to note that complete eradication of fungi in DUWLs has proven elusive, even with the application of disinfectants at varying concentrations, types, and frequencies. This highlights the pressing need for continued research efforts to develop new and optimized treatment protocols that are specifically tailored to eradicate fungi from DUWLs. Finally, it was notable that there are currently no specific regulations by any dental authority on permissible levels of fungi, as opposed to bacteria, in DUWLs. Legislation developed based on our findings can contribute to the standardization of practices and the formulation of effective control strategies for fungal contamination in DUWLs. It can also guide dental professionals in implementing regular monitoring, proper maintenance, and targeted disinfection protocols to minimize fungal contamination and ensure optimal water quality for patient safety., Competing Interests: Conflict of interest The author(s) below of the captioned paper have declared no potential conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Dental unit waterlines (DUWLs) are the conduits within the dental chair through which water derived from the municipal or other peripheral supply systems flows through the dental chair to reach the dental patient. The quality of the water so delivered must have a low pathogenic microbial burden so as to be safe for the patient and the dental personnel. Regulatory bodies have therefore set minimum standards for the quality of water that exits from DUWLs as part of routine infection control. Adopting a comprehensive approach that combines physical, chemical, and automated methodologies is recommended to effectively decontaminate DUWLs. This review discusses the complexities of DUWL decontamination in terms of (1) Best Practice Guidelines in dental healthcare settings to mitigate DUWL contamination, (2) origins of DUWL contamination and biofilm formation and the associated infectious risks, (3) contemporary approaches for minimizing DUWL contamination, and (4) constraints in combating biofilms in DUWLs. Compliance with regional and national regulations on DUWL decontamination is a legal obligation for all dental practitioners and fundamental to protecting public health., Competing Interests: Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Aims: The aim of this study was to evaluate the presence of yeasts in dental chair unit waterlines (DCUWLs) and to test their ability to form biofilms., Materials and Methods: Eighteen dental waterlines were analysed by culture in liquid Sabouraud in order to allow the quantification and the purification of isolated yeasts from their internal surfaces. All isolates were identified by standard laboratory procedures, including CHROMagar Candida medium for orientation, commercial yeast identification system Api Candida, MALDI-TOF MS and DNA sequencing. To evaluate their kinetics of antifungal susceptibility during different phases of biofilm formation, these yeasts were subjected to three antifungal agents., Results: From the 18 DCUWLs studied, 10 were altered (55.56%). Eleven strains of Candida sp. [Candida albicans (2), Candida guilliermondii (5) and Candida glabrata (4)] and two species of non-Candida; Rhodotorula spp. (1) and Trichosporon spp. (2) were identified. The majority of yeasts in planktonic form were susceptible to amphotericin B, caspofungin and voriconazole, except C. albicans was resistant to voriconazole. In the biofilm form, caspofungin was the most effective antifungal agent for all isolated strains. For the other antifungal agents, sessile cells were resistant., Conclusion: Several types of yeasts were identified; the most frequently isolated genus was Candida. The majority of these yeasts had the ability to form biofilms and resisted antifungal agents used in this study., (© 2018 FDI World Dental Federation.)

Introduction: Dental unit waterline (DUWL) output water is delivered through instruments of a dental chair unit (DCU) to irrigate and cool teeth. However, these waterlines can be heavily contaminated with bacteria., Aim: The purpose of the present study was to assess retraction and investigate the contamination level and prevalence of bacteria in DUWL output water., Methods: Fifty-eight DCUs were randomly selected from 30 hospitals in 10 districts of Tianjin, one of the four special municipalities of China. A unique sampling connector was used in place of the dental handpiece to collect water samples. Evaluation of retraction was accomplished using a retraction measurement device designed in accordance with the International Standard ISO 7494-2:2015(E)., Results: A total of 263 water samples were collected, and the highest concentration of bacteria [1.8 × 10(6) colony-forming units (CFU)/mL] was found in the handpiece group. Thirty (51.72%) water samples in the handpiece group and 21 (36.21%) in the air/water syringe groups were cultured, yielding colony counts of > 500 CFU/mL. Potential infectious agents, such as Bacillus cereus, Kocuria kristinae and Pseudomonas fluorescens, were isolated from the water samples. Thirty (51.72%) DCUs failed the retraction evaluation. There was a significant, positive correlation (P < 0.05) between the concentration of bacteria in the water sample and the retracted volume., Conclusion: It is of paramount importance to increase compliance with the standards for controlling DUWL contamination. Routine microbial monitoring and evaluation of retraction are necessary to provide high-quality water for use in dental treatment., (© 2016 FDI World Dental Federation.)

Aim: The purpose of the present study was to evaluate the effect of an ultrafiltration system on the bacteriological water quality in dental units., Design: A BIN-X UF-45R ultrafiltration system with a pore membrane of 0.03 microm was mounted at the water supply of six older dental units while six control units were disinfected with sodium hypochlorite according to a standard procedure. As the water quality in the test units deteriorated in spite of ultrafiltration the test units were subjected to chlorination at different concentrations several times during the test period., Outcome Measure: The number of colony forming units (cfu)/ml in water was determined according to European Standards on water quality., Results: While the median number of cfu/ml in control units never exceeded 7.6x10(1) the median cfu/ml in test units increased up to >1x10(5) in 3-4 days every time chlorination of the units was interrupted., Conclusion: The ultrafiltration system mounted at the water supply for six dental units was not able to control the bacteria originating from the existing biofilm in the water lines and deliver water of an acceptable quality.

Unlabelled: Dental Unit Water Systems (DUWS) are used in dental practices to provide water for cooling of dental equipment and irrigation of the oral cavity. However, they have been demonstrated to be contaminated with micro-organisms. There are currently no European Union (EU) Commission guidelines for the microbial quality of water discharged by DUWS. This study was part of an EU research programme to investigate the microbial contamination of DUWS in general dental practice (GDP) in the UK, Denmark, Germany, The Netherlands, Ireland, Greece and Spain., Objective: To undertake a questionnaire survey on the type of DUWS in use and determine the attitude of GDPs to the risk of microbial infection from DUWS., Materials and Methods: The questionnaire was written and translated into the language of each country before being posted to each participating dentist. Dentists were asked to complete the questionnaire survey and return it by post., Results and Conclusions: The major findings were that the majority of dentists did not clean, disinfect or determine the microbial load of their DUWS, and that dentists would welcome regular monitoring and advice on maintaining their DUWS; the introduction of guidelines; and recommendations on controlling the microbial load of DUWS.

Aim: The objective of this study was to measure the microbial contamination released from dental unit air lines (DUAL) and dental unit water lines (DUWL)., Materials and Methods: Emissions from DUAL and DUWL from five dental units supplied by a central water source (tap) and a centralised air supply were sampled three times over a five- week period. Air was forced through sterile water and then plated onto selective agar using apparatus designed to spread the sample solution evenly, and then incubated at room temperature for seven days. Colonies were then counted and the concentration of bacteria present was determined and expressed as colony forming units per millilitre (cfu/ml) per minute. The same procedure was used to evaluate five other dental units, which had attached independent water reservoir (bottle) systems (IWR). Only deionised water was added to the bottles and unit waterlines were cleaned weekly with alkaline peroxide based solution. Values were expressed as cfu/ml., Results: Air and water specimens obtained from dental units supplied with tap water had microbial counts significantly (t-test, p < 0.05) greater than IWR dental units., Conclusions: Results indicate that IWR can reduce the numbers of micro-organisms released from DUWL. However, the effectiveness of such systems should be routinely monitored. Emissions from DUAL seems to reflect the levels of microbial contamination present in DUWL.

Aim: To evaluate drying of the dental unit waterlines (DUWL) as a new method of controlling the bacterial biofilm therein and thereby to reduce the number of living bacteria in dental unit water., Setting: 18 dental units were incorporated into the study. Six units constituted the experimental units, which were emptied for stagnant water in the DUWL every night; six units were chlorinated every night (positive controls), and six units were left untreated (negative controls)., Outcome Measure: Water samples from the ultrasonic scaler were examined microbiologically according to the guidelines from the Danish Standard Association and the number of colony forming units (cfu) per ml of water was determined., Result: Drying of DUWL did not reduce the number of cfu per ml in dental unit water below the levels found in DUWL left untreated., Conclusion: The drying of the waterlines for about 16 hours per day during a 19-day period did not result in reduced counts of bacteria in water samples from the experimental units.

Aims and Objectives: Currently, as a preventive measure against air contamination caused by dental procedures, dust-collecting aspirators such as an extra-oral vacuum aspirator (EOVA) are coming into general use. In this study, we tested the ability of a modified EOVA that uses a household vacuum machine., Design and Setting: The study was conducted in two parts. First, the modified EOVA was tested for its ability to eliminate an Escherichia coli aerosol generated in a manikin. Second, the device was tested for its ability to remove the aerosol generated by dental treatment procedures, scaling and drilling a tooth, on human subjects., Results: There was a statistically significant reduction in both the E. coli aerosol and the oral bacterial aerosol during dental treatment procedures., Conclusion: The modified EOVA machine is highly effective in preventing air contamination by dental procedures. Its main advantages are that it can easily be modified for use with any dental unit and it is relatively inexpensive.

The changing profile of oral care rendered through the Mobile Dental System (MDS), after the introduction of the Atraumatic Restorative Treatment (ART) approach is described. During the first year of introduction of ART, the percentages of amalgam restorations and tooth extractions decreased significantly (P < 0.0001). This is partly ascribed to a change in choice of treatment by dental operators in favour of ART and also due to an increase in acceptance by patients because of the reduced fear, and the patient-friendly nature of the ART approach. The reduction in amalgam restorations was 16.0 per cent for permanent and 1.4 per cent for primary posterior teeth. Extraction of posterior teeth was reduced by 17.4 per cent in the permanent and 35.7 per cent in the primary dentitions. The restorative component of oral care increased by 33.4 per cent in the permanent and 37.1 per cent in primary posterior teeth. The one-year survival of one-surface ART restorations using Fuji IX and KetacMolar was 93.6 per cent. Full and partial (more than 90 per cent) retention of the sealant part of the ART restoration was obtained in 75 per cent of the cases after one-year. During the one-year period, infection control was made more simple and this facilitated easier maintenance of mobile dental equipment. The introduction of the ART approach reduced extraction, restored more teeth and made oral care in the MDS more preventive, less threatening and thus more patient-friendly.

The quality of dental unit water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. The unique feature of dental chair water lines is the capacity for rapid development of a biofilm on the dental water supply lines combined with the generation of potentially contaminated aerosols. The biofilm, which is derived from bacteria in the incoming water and is intrinsically resistant to most biocides, then becomes the primary reservoir for continued contamination of the system. Dental water may become heavily contaminated with opportunistic respiratory pathogens such as Legionella and Mycobacterium spp. The significance of such exposure to patients and the dental team is discussed. There is at the present time, no evidence of a widespread public health problem from exposure to dental unit water. Nevertheless, the goal of infection control is to minimise the risk from exposure to potential pathogens and to create a safe working environment in which to treat patients. This paper evaluates the range of currently available infection control methods and prevention strategies which are designed to reduce the impact of the biofilm on dental water contamination, and are suitable for use in general practice. Bacterial load in dental unit water can be kept at or below recommended guidelines for drinking water (less than 200 colony forming units/ml) using a combination of readily available measures and strict adherence to maintenance protocols. Sterile water should be employed for all surgical treatments.