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Dental simulation head model laboratories are crucial for clinical simulation training for stomatological students, yet the maintenance of their dental unit waterlines (DUWLs) has been overlooked. This study investigated water contamination in DUWLs within these laboratories and proposed solutions. Water samples were collected from 12 dental chairs in three laboratories at three time points: the beginning, middle, and end of the semester. At the start of the semester, severe contamination was observed, with colony counts of 11,586[Formula: see text]1715 CFU/ml for high-speed handpieces and 5375[Formula: see text]874 CFU/ml for three ways syringes. As the semester progressed, colony counts gradually decreased but remained above clinical thresholds. Both 20 mg/L organochlorine disinfectant and 20 mg/L chlorine dioxide were effective in reducing bacterial contamination below standard ranges three days post-disinfection. Microbial diversity analysis revealed Proteobacteria and Bacteroidota as the dominant bacterial phyla, with Ascomycota as the dominant fungal phylum. Potentially pathogenic bacteria such as Pseudomonas, Burkholderia-Caballeronia-Paraburkholderia, Ralstonia, Mycobacterium, Legionella, Paenibacillus, Streptomyces, Acinetobacter, and Prevotella, as well as fungi like Fusarium and Penicillium, were detected. Therefore, urgent attention is needed to address DUWL contamination in dental laboratories, and it is recommended to disinfect DUWLs using either 20 mg/L organochlorine disinfectant or 20 mg/L chlorine dioxide every three days., Competing Interests: Competing interests: The authors declare no competing interests. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable., (© 2025. The Author(s).)

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.)

Background: Microorganisms in dental unit water (DUW) play a significant role in dental bioaerosols. If the methods used to decontaminate DUW also help improve air quality in dental clinics is worth exploring. In this study, we aim to identify the source of bacteria in dental bioaerosols and investigate the impact of waterline disinfectants on the quantity and composition of bacteria in DUW and bioaerosols., Methods: Two dental chair units in a separate treatment room are installed with two different waterline decontamination systems, a plasma or iodine cartridge. The experiment was performed in two phases, before and after installing the decontamination systems. Aerosol is generated via running airotor in the subject's mouth. Before and after the procedure, the air samples were collected with an active air sampling machine onto agar plate and filter paper for genomic DNA extraction. The subject's saliva and DUW samples were also collected. The samples were analyzed further with bacterial counting and metataxonomics analysis., Results: The bacteria present in the air sample after the aerosol-generating procedure were confirmed to be derived from the air-before, saliva, and DUW in 51.43%, 6.38%, and 18.60%, respectively. The saliva samples demonstrated the highest alpha diversity (within the sample), whereas the air samples had the least. Both waterline disinfectants effectively controlled bacteria in DUW but did not affect the bacterial number and composition in the air., Conclusions: Dental bioaerosols are composed of bacteria from saliva and DUW. Plasma and iodine showed a trend in controlling bacterial contamination in DUW but did not alter the bacterial count and composition in dental bioaerosols., Competing Interests: Declarations. Ethical approval: The study protocol was approved by the Ethics Committee (HREC-DCU 2023 − 129) of the Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand, and biosafety approval was granted by the Institutional Biosafety Committee (DENT CU-IBC 034/2023) of the Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Consent for publication: Not applicable. Generative AI and AI-assisted technologies in the writing process: During the preparation of this work, the authors utilized ChatGPT 3.5 to enhance grammar and improve the manuscript’s clarity. Subsequently, the authors thoroughly reviewed and edited the content as necessary, assuming full responsibility for the published article’s content. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Bacterial contamination of outlet water from dental unit waterlines (DUWLs) may lead to healthcare-associated infection. The aim of this study was to evaluate the contamination of DUWLs from new dental chairs before and after their initial shock disinfection with ICX Renew® and to determine the efficacy of this method of shock disinfection., Methods: The microbiological quality of water samples obtained from the DUWLs of 17 new dental chairs installed at the University Hospital of Nancy, France, was assessed. Water samples were collected before and after an initial shock disinfection with one ICX Renew® treatment. Water analysis was used to assess total culturable aerobic bacteria (TCAB) at 22°C and 36°C, Legionella sp., Pseudomonas aeruginosa and total coliforms., Results: All the DUWLs (17/17) were contaminated by viable aerobic bacteria (TCAB at 22°C and 36°C > 300 CFU/mL), including P. aeruginosa, before shock disinfection. After shock disinfection with ICX Renew®, 24% of DUWLs (4/17) remained contaminated by aerobic bacteria (TCAB at 36°C > 300 CFU/mL for 3/17) and P. aeruginosa (> 100 CFU/100 mL for 1/17)., Conclusions: To reduce the contamination of new dental chairs, initial shock disinfection of DUWLs should be performed to remove biofilms and bacteria from the DUWLs. To ensure the security of care, microbiological analysis of outlet water from DUWLs should be systematically performed before the first clinical use of a new dental chair to determine the efficacy of shock disinfection and the agreement of the results with the dental recommendations for water quality., Clinical Trial Number: Not applicable., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: It is essential to control the microbiology of dental unit water lines (DUWs) to prevent the spread of nontuberculous mycobacteria (NTM) and associated oral diseases. Therefore, the objective of this study was to quantify the presence of NTM in the water of 112 DUWs from dental centers and 57 DUWs from individual dental offices in Tehran, Iran., Methods: A total of 169 water samples were collected from DUWs. After filtration through a 0.45 μm membrane, the samples were decontaminated with 0.005 % cetylpyridinium chloride and then cultured on two Lowenstein-Jensen media, incubated at 25 °C and 37 °C for 8 weeks. Positive cultures for mycobacteria were analyzed using phenotypic tests, and the NTM species were identified through 16S rDNA, rpoB, and hsp65 genes analysis. Drug resistance was also assessed., Results: Of the total isolates, 38 (34.5 %) were classified as slow-growing mycobacteria (SGM), while 72 (65.5 %) were categorized as rapid-growing mycobacteria (RGM). NTM isolates were identified using molecular tests, including M. chelonae, M. abscessus, M. lentiflavum, M. mucogenicum, M. fortuitum, M. kansasii, M. simiae, M. gordonae, M. conceptionense, M. phocaicum, M. porcinum, and M. aurum. The NTM counts ranged from 50 to >500 CFU/500 mL across these 188 samples, with a median of 350 CFU/500 mL. Additionally, we reported two cases of intraoral infection caused by M. abscessus and M. chelonae, where the source of infection was traced to NTM-contaminated DUWs., Conclusions: The study found that most DUWs contained water contaminated with NTM, posing a potential health risk to humans. This research underscores the necessity of stringent quality control and certification of DUW water, with particular emphasis on ensuring the absence of NTM., Competing Interests: Declaration of competing 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 paper., (Copyright © 2024 Elsevier Ltd. 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.)

Water contamination in dental unit waterlines (DUWLs) is a potential source of healthcare-associated infection during dental care. The aim of this study was to evaluate the microbiological quality of DUWLs water from newly installed dental chairs in a French University Hospital. The microbiological quality of water from 24 new DUWLs initially disinfected by ICX Renew-prior to use of the dental units for patient treatment-was assessed for total culturable aerobic bacteria at 22°C and 36°C, Legionella sp. , Pseudomonas aeruginosa , and total coliforms. Among the 24 samples analyzed, 21 were compliant with the water quality levels: 19 had no bacteria, and 2 contained only 4 and 1 CFU/mL for total culturable aerobic bacteria at 22°C and 36°C, respectively. Three samples were non-compliant due to contamination by P. aeruginosa (4, 2, and 2 CFU/100 mL). Controlling and preventing the microbiological contamination of DUWLs, especially by pathogenic bacteria, at the time of the installation of the new dental chairs are crucial to prevent healthcare-associated infection in dentistry., Importance: Dental unit waterlines (DUWLs) of new dental chairs may be contaminated before their first clinical use, so an initial shock disinfection is crucial at the time of their installation. The microbiological analyses are crucial to control the water quality of DUWLs before their first clinical use because their disinfection does not guarantee the elimination of all bacteria., Competing Interests: The authors declare no conflict of interest.

Background: Ensuring the safety of dental unit waterlines (DUWLs) has become a pivotal issue in dental care practices, focusing on the health implications for both patients and healthcare providers. The inherent structure and usage conditions of DUWLs contribute to the risk of biofilm formation and bacterial growth, highlighting the need for effective disinfection solutions.The quest for a disinfection method that is both safe for clinical use and effective against pathogens such as Staphylococcus aureus and Escherichia coli in DUWLs underscores the urgency of this research., Materials: Chlorine dioxide disinfectants at concentrations of 5, 20, and 80 mg/L were used to treat biofilms of S. aureus and E. coli cultured in DUWLs. The disinfection effectiveness was assessed through bacterial counts and culturing. Simultaneously, human skin fibroblast cells were treated with the disinfectant to observe changes in cell morphology and cytotoxicity. Additionally, the study included corrosion tests on various metals (carbon steel, brass, stainless steel, aluminum, etc.)., Results: Experimental results showed that chlorine dioxide disinfectants at concentrations of 20 mg/L and 80 mg/L significantly reduced the bacterial count of S. aureus and E. coli, indicating effective disinfection. In terms of cytotoxicity, higher concentrations were more harmful to cellular safety, but even at 80 mg/L, the cytotoxicity of chlorine dioxide remained within controllable limits. Corrosion tests revealed that chlorine dioxide disinfectants had a certain corrosive effect on carbon steel and brass, and the degree of corrosion increased with the concentration of the disinfectant., Conclusion: After thorough research, we recommend using chlorine dioxide disinfectant at a concentration of 20 mg/L for significantly reducing bacterial biofilms in dental unit waterlines (DUWLs). This concentration also ensures satisfactory cell safety and metal corrosion resistance., (© 2024. The Author(s).)

Background: In Mexico and around the world, water in dental units, including triple syringes, comes from municipal chlorinated water mains. The microbial contamination of dental unit water systems constitutes a risk factor for opportunistic infections., Objectives: The present work aimed to identify the bacteria present in the triple-syringe water lines of dental units at a dental school of a public university in Mexico, with a hypothesis that opportunistic bacteria of importance to human health would be found., Material and Methods: A cross-sectional study was carried-out. A total of 100 samples of triple-syringe tubing from dental units operated by a dental school of a public university in Mexico were analyzed before and after their use in dental practice. Bacterial biofilm was cultured and isolated from the tubing, using standard microbiological methods, and then the species present were identified through 16S rRNA gene sequencing. The characterization of the biofilm was performed by means of scanning electron microscopy (SEM)., Results: Bacterial growth was observed in 20% of the non-disinfected and 10% of the disinfected samples, with 11 strains isolated. Six genera and 11 bacterial species were genetically identified. Coagulasenegative staphylococci (CoNS), considered opportunistic human pathogens, were among the most critical microorganisms. Scanning electron microscopy revealed a thick polymeric matrix with multiple bacterial aggregates., Conclusions: Opportunistic bacteria from human skin and mucous membranes were detected. Under normal conditions, these bacteria are incapable of causing disease, but are potentially harmful to immunosuppressed patients.

Background: Dental Unit Water Line (DUWL) deliver water to different handpieces in a dental unit. The water in DUWL circulates in a closed system, where it is taken from a container. The quality of dental water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from dental equipment. Output water from DUWLs may be a potential source of infection for both dental health care personnel and patients., Aim: To assess the microbial contamination in the DUWL among dental clinics in Chennai., Materials and Methods: An in vitro study was conducted on 60 water samples from 20 dental clinics in Chennai in December 2019. Water samples were collected from three different sources of the Dental unit according to ADA guidelines. The collected samples were assessed for the presence of Aspergillus, Acinetobacter, Pseudomonas aeruginosa, and Legionella by agar plate method. The data were analysed using SPSS software version 20., Results: Legionella was the most prevalent microorganism with 70% prevalence in a three-way syringe and 50% in scaler and airotor, followed by Pseudomonas aeruginosa and Acinetobacter with 10% prevalence in scaler and airotor and Aspergillus with a prevalence of 10% in the three-way syringe., Conclusion: Most of the dental units were contaminated with Aspergillus, Legionella, Pseudomonas aeruginosa and Acinetobacter which pose a serious threat to the patients as well as the dentists., (Copyright © 2024 Copyright: © 2024 Indian Journal of Dental Research.)

Background: In dentistry, nosocomial infection poses a great challenge to clinicians. The microbial contamination of water in dental unit waterlines (DUWLs) is ubiquitous. Such infected DUWLs can transmit oral microbes in the form of aerosols. Previous studies have suggested treating DUWLs with various disinfectants to reduce cross-contamination. The literature lacks a comparative evaluation of the effect of the use of 0.2% chlorhexidine (CHX) and 0.1% sodium hypochlorite (NaOCl) in DUWLs on aerosolized bacteria generated during dental procedures., Objective: To compare the effect of NaOCl and CHX in DUWLs on aerosolized bacteria generated during restorative and endodontic procedures., Materials and Methods: A total of 132 patients were equally divided into three groups (n = 44 in each group) according to the content of DUWL as follows. Group I-0.1% NaOCl Group II-0.2% CHX Group III-distilled water (Positive control) One-way ANOVA was performed and the Kruskal-Wallis test was used for intergroup comparison., Results: For the restorative procedure, inter-group comparison of mean colony-forming units (CFU) scores showed a statistically significant difference between the groups (p - .001) with the score of group 3 higher than group 2 followed by group 1. For the endodontics, an inter-group comparison of CFU scores showed a statistically significant difference between the groups (p - .003) with the mean score in group 1 being the lowest and group 3 being the highest., Conclusion: The addition of NaOCl or CHX in DUWLs shows an effective reduction in aerosolized bacteria compared to distilled water., (© 2023. The Author(s).)

Backgrounds: Numerous studies have shown that dental unit water lines (DUWLs) are often contaminated by a wide range of micro-organisms (bacteria, fungi, protozoa) and various prevalence have been reported for it in previous studies. Therefore, this review study aims to describe the prevalence of bacterial biofilm contamination of DUWLs., Methods: This is a systematic review and meta-analysis in which the related keywords in different international databases, including Medline (via PubMed) and Scopus were searched. The retrieved studies were screened and the required data were extracted from the included studies. Three standard methods including American Dental Association (ADA), The Center for Disease Control and Prevention (CDC) and contaminated > 100 CFU/ml(C-100) standards were used to assess the bacterial biofilm contamination of DUWLs. All studies that calculated the prevalence of bacterial biofilm contamination of DUWLs, and English full-text studies were included in the meta-analysis. Studies that did not have relevant data or used unusual laboratory methods were excluded. Methodological risk of bias was assessed by a related checklist and finally, the data were pooled by fixed or random-effect models., Results: Seven hundred and thirty-six studies were identified and screened and 26 related studies were included in the meta-analysis. The oldest included study was published in 1976 and the most recent study was published in 2020. According to the ADA, CDC and C-100 standards, the prevalence of bacterial contamination was estimated to be 85.0% (95% confidence interval (CI): 66.0-94.0%), 77.0% (95%CI: 66.0-85.0%) and 69.0% (95%CI: 67.0-71.0%), respectively. The prevalence of Legionella Pneumophila and Pseudomonas Aeruginosa in DUWLs was estimated to be 12.0% (95%CI: 10.0-14.0%) and 8.0% (95%CI: 2.0-24.0%), respectively., Conclusion: The results of this review study suggested a high prevalence of bacterial biofilm in DUWLs; therefore, the use of appropriate disinfecting protocol is recommended to reduce the prevalence of contamination and reduce the probable cross-infection., (© 2023. The Author(s).)

Abstract: The water quality of dental unit waterlines (DUWLs) is associated with patient safety. No program for DUWL water quality improvement has been formulated since the time they were established 20 years ago. This study provides an improvement program for the quality of dental unit water. The improvement program was implemented step by step: discharge of DUWLs for 5 minutes in the morning before clinical service to flush out the water left in the pipeline overnight; weekly disinfection of the handpiece connector with 75% alcohol and replacement of the old connector when the water quality of the same dental chair unit (DCU) was continuously found to be unqualified; monthly disinfection of the water supply system and pipeline; and establishment of DCU maintenance work standards and staff education and training. From 2016 to 2018, the water quality of 18 DCUs was tested by microorganism culture. The colonies >200 colony forming unit were categorized as unqualified. This program was divided into a pre-test phase, Phase 1, a maintenance phase, and Phase 2. A Chi-square test was used to calculate the difference of unqualified water quality numbers between each phase of the improvement program. In the pre-test phase, the water quality rate (high quality number/high-quality number + low-quality number) was 58.3%. In Phase 1, the quality rate before and after the intervention was 64.8% (35/54) and 92.2% (83/90) (P < .001), respectively. After Phase 1, the quality rate reached 100%. However, the quality rate dropped to 75% during the maintenance phase. Then, we proceeded into Phase 2 of the improvement program by further monthly disinfection to DUWLs. In Phase 2, the quality rate was 62/73 (84.9%) and improved to 142/144 (98.6%) after the intervention (P < .001). The quality rate reached 100% once again and was maintained at 100% thereafter. In conclusion, the 4 steps of the improvement program improved the water quality of the DUWL, which is important for patient safety., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Oral health care workers (OHCW) are exposed to pathogenic microorganisms during dental aerosol-generating procedures. Technologies aimed at the reduction of aerosol, droplets and splatter are essential. This in vivo study assessed aerosol, droplet and splatter contamination in a simulated clinical scenario. The coolant of the high-speed air turbine was colored with red concentrate. The red aerosol, droplets and splatter contamination on the wrists of the OHCW and chests of the OHCW/volunteer protective gowns, were assessed and quantified in cm 2 . The efficacy of various evacuation strategies was assessed: low-volume saliva ejector (LV) alone, high-volume evacuator (HV) plus LV and an extra-oral dental aerosol suction device (DASD) plus LV. The Kruskal-Wallis rank-sum test for multiple independent samples with a post-hoc test was used. No significant difference between the LV alone compared to the HV plus LV was demonstrated ( p = 0.372059). The DASD combined with LV resulted in a 62% reduction of contamination of the OHCW. The HV plus LV reduced contamination by 53% compared to LV alone ( p = 0.019945). The DASD demonstrated a 50% reduction in the contamination of the OHCWs wrists and a 30% reduction in chest contamination compared to HV plus LV. The DASD in conjunction with LV was more effective in reducing aerosol, droplets and splatter than HV plus LV.

Dental unit water systems (DUWS) provide an excellent environment for biofilm formation and can form a potential health risk for patients and staff. To control this biofilm formation, better understanding of the DUWS biofilm ecology is needed. Described is a newly developed in-vitro DUWS model which is easy to build, can be inoculated with different water sources and allows for sampling of both the effluent and biofilm. Unlike most models, a dynamic flow pattern, typical for a dental unit is used to provide water as a nutrient source. Microbial growth and composition were analyzed using heterotrophic plate counts (HPC) and 16S rDNA sequencing. Growth was reproducible in all models, reaching quasi-steady state at day 16 in the effluent (10 5 -10 6  CFU∙mL -1 ) and day 23 in the biofilm (10 8 and 10 7  CFU∙cm -2 ) for non-potable and potable water, respectively. Principal component analysis of the microbial composition showed that biofilms originating from either non-potable or potable water were significantly different after 30 days of growth (n = 8, PERMANOVA, F = 35.6, p < .005). Treatment of the biofilms with 1000 ppm active chlorine showed a biological and statistical significant decrease in viable counts in the effluent phase to below the detection limit of 100 CFU∙mL -1 . The HPC returned to pre-treatment levels within 14 days. Using this model results in inoculum dependent biofilms with a higher bacterial density compared to previously described models. The relative ease in which samples can be taken allows for the monitoring of antimicrobial disinfection efficacy on the effluent, biofilm and matrix., Competing Interests: Declaration of Competing 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 paper., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Three cases of severe odontogenic infections due to nontuberculous mycobacteria (NTM) in Venezuela that were directly associated with dental procedures and the finding of dental unit waterlines (DUWLs) in dental offices that were colonized with mycobacteria species was the reason for assessing the water quality of DUWLs in dental offices in two capital cities in South America, namely, Quito and Caracas. The main water supplies and the water from 143 DUWLs in both cities were sampled and especially checked for contamination with NTM. To measure the overall bacteriological quality of the water also the presence of heterotrophic bacteria, coliform bacteria, and Pseudomonas was determined. Results showed that respectively 3% and 56% of the DUWLs in Quito and Caracas yielded NTM species (up to 1000 colony-forming units (CFU)/mL). Furthermore, high and unacceptable total viable counts of heterotrophic bacteria and/or coliform bacteria and Pseudomonas were detected in 73% of the samples. We conclude that, in both cities, the water in the majority of DUWLs was contaminated with NTM and other potential pathogens, presenting a risk to human health. The detection of NTM in DUWL water with acceptable heterotrophic bacteria counts shows the need to include NTM in water quality testing. Mycobacteria are more resistant to disinfection procedures than other types of vegetative bacteria, and most testing protocols for DUWLs do not assess mycobacteria and thus do not guarantee risk-free water.

Mobile dental delivery systems (MDDSs) are receiving growing interest for reaching isolated patients, as well as in dental care for fragile and hospitalized patients, with the advantage of being able to be used from room to room or during general anesthesia (GA) in an operating room. Therefore, ensuring the care safety is crucial. The aim of this study was to elaborate and assess an MDDS maintenance protocol, containing the management of dental unit waterlines and adapted to specific conditions such as dental care under GA. A step-by-step protocol was established and implemented for an MDDS used during dental care under GA in children. Samples of the output water were collected at J0, J+1, 3, 6, 12, and 24 months, and cultured to observe the microbiological quality of the water. All the results (heterotrophic plate count at 22 °C, at 37 °C, and specific pathogenic germs sought) showed an absence of contamination. The protocol presented was effective over time and allowed ensuring the safety of care to be ensured when using MDDS, even during dental procedures under GA. As a result, it could be implemented by any dental care delivery structure wanting to reinforce the safety of its practice.

Water is essential during dental care. Physical and chemical techniques should be used to maintain a good water quality with respect to bacteria, and to ensure the safety of exposed patients and dental staff. The aim of this survey was to assess the modalities used by dental practitioners in Eastern France to maintain the water quality of their dental unit waterlines (DUWLs). A questionnaire about water quality maintenance practices was sent to 870 dental offices in 2016. The questionnaires were completed by 153 dental offices, covering about 223 dental care units. The majority of units were fed by mains water (91.0%), which is generally unfiltered (71.3%). One-third (33.6%) of the units had an independent water bottle reservoir. Flushing, a basic physical technique to improve the quality of units' outflow water, was practiced in 65.4% of dental offices. Concerning the chemical treatment of water, it was used for 62.1% of the units. An analysis of the microbiological quality of the DUWL water was only carried out in 2.6% of the offices. In conclusion, providing better training to dental staff seems necessary to improve their practices and to generalize procedures that improve the microbiological quality of the water used.

Dental unit waterlines (DUWLs) can be considered one of the possible routes of H. pylori transmission, although its presence in DUWLs has not yet been investigated thoroughly. The present study aimed to discover the prevalence of H. pylori and oral streptococci ( S. oralis and S. mutans ) in DUWLs to evaluate the risk of exposure to human pathogens in dental practices. We collected the output water from 60 dental chair units (DCUs) in 26 private dentistry settings in Turin, searching for H. pylori and oral streptococci (OS) DNA, with a polymerase chain reaction (PCR) technique. At the same time, dentists completed a questionnaire about their DCUs, their main activities, the presence of anti-retraction devices, their attitudes about disinfection, etc. No dental chair unit tested was contaminated with H. pylori or S. mutans ; only one dental chair was contaminated with S. oralis (1.7%). Considering the results, we can state that: (i) the lack of H. pylori DNA in water samples analyzed, suggests that municipal water is presumably treated with a sufficient chlorine level to inactivate DNA over time; (ii) the aspiration of oral fluids is limited by anti-retraction valves fitted distally to hand pieces; (iii) propidium monoazide qPCR (PMA-qPCR) could be a good technique to investigate and monitor potential environmental sources of infections such as DUWLs.

Studies conducted over the last 40 years have demonstrated that the water output from dental unit waterlines (DUWLs) is often contaminated with high densities of microorganisms. It has been monitored the microbiological quality of the water in 30 public dental facilities in northern Italy in order to assess the health risk for patients and dental staff. In each facility, samples of water both from taps and from DUWLs were analyzed in order to evaluate heterotrophic plate counts (HPCs) at 22 °C and 36 °C, and to detect coliform bacteria, Pseudomonas aeruginosa , Legionella pneumophila and amoebae. In 100% of the samples taken from the DUWLs, the concentration of HPCs was above the threshold as determined by the Ministère de la Santé et des Solidarités (2007). The concentration of P. aeruginosa was greater than the indicated threshold in 16.67% of the hand-pieces analyzed. A total of 78.33% of samples were contaminated by L. pneumophila , while in the samples taken from the DUWLs alone, this percentage rose to 86.67%. Amoebae were detected in 60% of the samples taken from hand-pieces; all belonging to the species V. vermiformis . This study documented the presence of various microorganisms, including Legionella spp., at considerably higher concentrations in water samples from DUWLs than in samples of tap water in the same facilities, confirming the role of the internal DUWLs in increasing microbial contamination, especially in the absence of proper management of waterborne health risks., Competing Interests: The authors declare no conflicts of interest.

Aims: This study aims to estimate the microbial presence on the surface of different brand new NiTi endodontic instruments for clinical use., Material and Methods: Eleven different types of NiTi rotary endodontic instruments, obtained from their fresh opened original packages, were assigned to three different groups, according to packaging type and sterilization and tested for bacterial contamination. Isolated bacteria were identified by using standard microbiological methods and then counted. Differences observed in groups were analyzed statistically by using the one-way analysis of variance (ANOVA) for dependent samples and the Tukey HSD post hoc test., Results: Statistical differences were found between instruments delivered in plastic boxes which bacterial count resulted higher than those obtained from instruments delivered in blisters (p<0.01)., Conclusions: Some brand new endodontic instruments showed degrees of bacterial contamination that both quantitatively and qualitatively deserve to be considered in clinical procedures.

Background: The quality and health safety of water used for refrigeration and flushing of the handpieces, water-syringes and other components of dental units is of considerable importance. Water crosses these devices by a system of intersected small plastic tubes (about 2 mm of diameter), named dental unit water lines (DUWLs). DUWLs may be heavily colonized by many bacterial species in a planktonic phase, adherent or in biofilm lifestyle, resulting in a potential risk of infection, not only for all professionals who routinely use these devices, but also for occasional-patients, especially immunocompromised patients. Contamination of DUWLs can be prevented or reduced with the use of disinfectants, but the eradication of microorganisms, especially which those are adherent or living in biofilm lifestyle on the inner surfaces of DUWLs is challenging and often, the normal methods of water disinfection are not effective. Moreover, disinfectants routinely used to disinfect DUWLs may alter the bond strength of the dentine bonding agent used for restorative practice in dentistry., Study Design: To identify an innovative and alternative strategy, able to prevent bacterial adhesion to DUWL surfaces through a physical approach, which is more effective in overcoming the problem of DUWL contamination and the risk of infection compared to the standard methods already in use. In this pilot study we tested a member of the oral streptococci family, that is not a component of the biofilm detected on the walls of DUWL, but is frequently detected in water samples from DUWL, due to human fluid retraction during dental therapy. Namely, the pathogenic bacterial species Streptococcus mutans., Methods: We employ elastic acoustic waves at high-energy in preventing S. mutans adhesion to the inner walls of an experimental water circuit reproducing a DUWLs. To stress the capability of acoustic waves to interfere with bacterial adhesion also in extreme conditions, a high S. mutans contamination load was adopted., Results: We observe a significant decrease of adherent bacteria exposed to acoustic waves treatment respect to control., Conclusion: This study demonstrates the effectiveness of acoustic waves in counteracting the adhesion of S. mutans to the inner walls of an experimental water circuit reproducing a DUWL, opening up new prospects for future practical applications. The interesting results, so far obtained, require an in-depth analysis of the methods regarding both the various bacterial species involved and the infective charges to be used.

Susceptibility testing of bacteria to disinfecting chemical agents isolated from dental unit waterlines (DUWL) is necessary for the development of effective disinfectant products. However, until now, susceptibility tests for chemical agents, which are components of DUWL disinfectant products, have not been conducted on bacteria isolated from DUWL water. The aim of this study was to evaluate and compare the susceptibilities of DUWL isolates in planktonic and biofilm states to cetylpyridinium chloride, as well as to the four chemical agents currently used for DUWL management. A total of 56 isolates, including 12 genera, were identified by 16S rDNA sequencing, and one strain of each genus was selected for susceptibility testing. A total of 12 isolates were used for the susceptibility tests. We determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the planktonic state and the minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) for the biofilm state using microtiter plates. MIC, MBC, MBIC, and MBEC of the 12 isolates for ethanol were the highest, followed by sodium hypochlorite, hydrogen peroxide, and chlorhexidine. Similar to chlorhexidine, the lowest MIC, MBC, MBIC, and MBEC were found in cetylpyridinium chloride. The susceptibilities of the isolates for sodium hypochlorite and ethanol were similar in the planktonic and biofilm states. For hydrogen peroxide and chlorhexidine, the MBIC and MIC were similar, but MBEC was 256 times higher than MBC. The MBIC and MBEC of isolates for cetylpyridinium chloride were 128 and 256 times higher than the MIC and MBC, respectively. As far as we know, this was the first study reporting the susceptibility of DUWL isolates to cetylpyridinium chloride and chemical agents used for disinfecting DUWLs. Cetylpyridinium chloride, for which the DUWL isolates showed the highest susceptibility, could be used for disinfecting DUWLs.

Infection risk management in a dental unit waterline (DUWL) involves healthcare personnel and patients and is related to routine exposure to water and aerosols that may contain bacterial species. To improve water safety plans, maintenance, and sanitation procedures, analyses of heterotrophic plate counts (HPCs) at 36 °C, and two other microorganisms frequently associated with biofilms, Pseudomonas aeruginosa and Legionella spp., were performed in order to evaluate differences in microbiological contamination between two types of DUWLs: Type A, provided by a water tank, and Type B, directly connected to municipal water. The data showed that the water supply and water safety plan differentially influenced microbiological contamination: Type A DUWLs were more contaminated than Type B DUWLs for all microbiological parameters tested, with significant changes in the percentage of positive samples and contamination levels that were beyond the limits of standard guidelines. The results obtained show how the storage tank, the absence of anti-retraction valves, and the disinfection procedures performed are the main critical points of Type A DUWLs, which confirms that dental unit management (maintenance/sanitization) is often missed or not correctly applied by stakeholders, with an underestimation of the real risk of infection for patients and operators.

Disinfection is a crucial aspect of patient care in dentistry. In the pre-19th century era, natural elements like acids, sulfur, mercury, and various alkaline metals were valued for their ability to obliterate pathogens. More recently aerosols, sprays, and disinfectant wipes with more powerful chemicals including quaternary ammonium compounds and aldehydes have become popular. As aerosols fall out of favor due to their health and environmental risks, disinfectant wipes are becoming the most trusted form of clinical sanitization. This article explores the history as well as the current practice of disinfection in the dental profession and further explores the variations in the use of surface disinfection based on the published literature. The current practice guidelines as recommended by agencies like Centers for Disease Control (CDC) were studied and summarized for this review.

Water from the waterlines of dental units is often contaminated with bacteria but there have been few studies accurately assessing the diversity of these bacterial populations. The aim of our study was to assess the bacterial diversity present in water collected from dental unit waterlines using the Illumina MiSeq. Water was collected from two separate dental units located in a dental hospital and two units found in two separate private clinics in Gangneung-si, Korea. From the four water samples that were analyzed, a total of 233 bacterial genera were identified. The most abundant genera were Sphingomonas (25%), Halomonas (20%), Reyranella (8%), and Novosphingobium (6%). Halomonas was more prevalent in the two dental units located at the dental hospital, while Reyranella and Sphingomonas were more commonly found in the private dental clinics. Only 19 of the 233 identified genera were common between water samples from all dental units. Opportunistic pathogens were shown to account for 7.7% of the total bacterial genera identified. Our results have demonstrated that there is a wide assortment of bacterial genera present in dental unit waterlines.

Biofilm on dental unit waterlines can spread microbial contamination in the water. The aim of this study was to investigate microbial contamination of water from supplies and dental units before and after the implementation of a protocol for microbial quality improvement and maintenance of dental unit water. The microbial load was evaluated in water from 27 taps and dental units (reservoirs, air-water syringes and highspeed outputs without handpieces) using the PetrifilmT system (total aerobic bacteria and fungi) and conventional culture media (enterobacteria and Legionella spp.). The bacterial load in water samples from taps and reservoirs was within the parameter established by Brazilian legislation (<500CFU/mL); but the bacterial load in samples from air-water syringes and high-speed outputs without handpieces was not. The implementation of the protocol for the maintenance of microbial quality in dental unit water reduced bacterial load in highspeed outputs without handpieces (p=0.004). Enterobacteria and Legionella spp. were not isolated from any of the water samples from taps and dental units., (Sociedad Argentina de Investigación Odontológica.)

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.)

The study aims to evaluate the microbial contamination in dental unit water system (DUWS) in Chandigarh, India, including knowledge, attitude, and practices of general dental practitioners (GDPs) to reduce the microbiological risks of DUWS. Microbiological risks were assessed by collecting water samples from 18 dental chair units including three main water supply units. Total of 44 water samples were examined for bacteriological contamination and the highest microbial contamination was observed in the ultrasound scalers having a range of 100 to 12,000 CFU/ml, with a median count of 950 CFU/ml. Only 2.3% of the water samples met the European Union recommendation of less than 100 CFU/ml, whereas 97.7% of the water samples have the total bacterial count exceeding 100 CFU/ml. In comparison to Center for Disease Control (CDC) guidelines, only 20.5% water samples fall within the recommended quality of drinking water (less than 500 CFU/ml), and the rest of the samples (79.5%) exceed the total bacteria count with a median count of 1100 CFU/ml. Acinetobacter species, Pseudomonas aeruginosa, and Sphingomonas paucimobilis were found in most of the water samples from DUWS. Dental chair units show higher microbial load and hence failed to meet any international guidelines, e.g., CDC. The highest microbial contamination was observed in ultrasound scaler and air/water syringe outlets. Hence, the study demand for Indian guidelines for the type of water used in DUWS water and urges for the proper training of GDPs to avoid further risks to the dental patients.

This study aims to explore the water quality of dental unit waterlines (DUWLs) and the diversity of microbial communities in DUWLs. Water samples from 33 dental chair units (DCUs) were collected, diluted and then spread on sterilized R2A plate for incubation. Subsequently, the microbial colony-forming units per milliliter (CFU/ml) were recorded by an automatic colony analyzer. Total DNA extracted from the rest of the samples was tested on the Illumina MiSeq PE300 platform. T-test and Kruskal-Wallis rank test were adopted for statistical analysis. Significance was assumed at a P<0.05. After incubation, the average total microbial count was 21,413.13±17,861.00CFU/ml. High-throughput sequencing revealed 10 bacterial phyla, including 9 identified and 1 unclassified phyla. Totally 63 sequences were identified at the genus level, including 42 genera, 3 tentative species and 18 unclassified genera. In addition, 7 potential human pathogenic bacteria were detected. In summary, department, brand and service life of DCUs do not influence the water quality of DUWLs significantly. The diversity of microbial communities in DUWLs is abundant and includes both pathogenic and some unknown bacteria., (Copyright © 2017. Published by Elsevier Ltd.)

In this study we evaluated (1) the efficacy of a protocol that combines hydrogen peroxide (shock treatment) and ICX ® tablets (continuous treatment) for the control of microbial contamination in dental unit water lines, and (2) the in vitro antimicrobial activity of ICX ® tablets on collection and wild strains isolated from dental chair output waters. To assess the treatment effectiveness, the microbial load in the output water samples of three dental chairs were investigated: one control chair received only shock treatment. In vitro bactericidal activity was tested against Staphylococcus aureus and Pseudomonas aeruginosa. Data obtained from samples collected from chairs treated with ICX ® and shock treatment and data from the control chair did not differ significantly on the basis of microbial load. In the in vitro study, the product was unable to kill Gram-negative bacteria. These results show that the continuous introduction of ICX ® was not effective in maintaining low counts of the heterotrophic bacteria in the output water of dental devices, and shock treatment may be needed more frequently than monthly.

Legionella spp. are ubiquitous in aquatic habitats and water distribution systems, including dental unit waterlines. Surveys have shown that the percentage of samples taken at different dental sites that were positive for Legionella spp. were highly variable and ranged from 0% to 100%. Cultivation is the principal approach to evaluating bacterial contamination employed in the past, but applying this approach to testing for Legionella spp. may result in false-negative data or underestimated bacterial counts. PCR and direct fluorescent counts can detect viable non-cultivable bacteria, which are not counted by plating procedures. Legionella spp., commonly form such viable non-culturable cells and it is likely that they contribute to the difference between plate count results and those of PCR and fluorescent-antibody detection. However, studies have shown that Legionella is present in the municipal water source in spite of the current filtration and chlorination procedures. Once Legionella reaches the building water system, it settles down into a biofilm layer of stagnant water. By means of this layer, Legionella can protect itself from antimicrobial agents and then multiply. Dental unit waterlines may be contaminated with opportunistic bacteria. The water quality in the dental units should be controlled to eliminate opportunistic pathogens and to provide water for dental treatment that meets public health standards for potable water.

Introduction Dental care has become a challenge for healthcare associated infection prevention programs, since the environment, within other factors, plays an important role in the transmission chain. Materials and Methods An intervention program was designed for the Dental Unit of Hospital Militar de Santiago, between years 2014 and 2015. The program contemplated 3 stages: diagnostic, intervention and evaluation stage. Objective To improve the safety of critical surfaces involved in dental healthcare. Results During the diagnostic stage, the cleaning and disinfection process was found to be deficient. The most contaminated critical surface was the instrument holder unit, then the clean area and lamp handle. The surfaces that significantly reduced their contamination, after the intervention, were the clean area and the instrument carrier unit. Conclusion Training in the processes of cleaning and disinfecting surfaces and dental equipment is one of the cost-effective strategies in preventing healthcare-associated infections (HCAI), with simple and easy-to-apply methods.

In this study, a laboratory model to reproduce dental unit waterline (DUWL) biofilms was developed using a CDC biofilm reactor (CBR). Bacteria obtained from DUWLs were filtered and cultured in Reasoner's 2A (R2A) for 10 days, and were subsequently stored at -70°C. This stock was cultivated on R2A in batch mode. After culturing for five days, the bacteria were inoculated into the CBR. Biofilms were grown on polyurethane tubing for four days. Biofilm accumulation and thickness was 1.3 × 10 5  CFU cm -2 and 10-14 μm respectively, after four days. Bacteria in the biofilms included cocci and rods of short and medium lengths. In addition, 38 bacterial genera were detected in biofilms. In this study, the suitability and reproducibility of the CBR model for DUWL biofilm formation were demonstrated. The model provides a foundation for the development of bacterial control methods for DUWLs.

Background and Aim: Biofilms in dental unit waterlines (DUWLs), suction hoses, and fittings are a potentially significant source of cross-contamination posing significant health risk as these may come into contact with patients during treatment. The purpose of this in vitro study was to identify the spectrum of bacterial flora colonizing the DUWLs and to detect pathogenic microorganisms present in such an environmental niche., Materials and Methods: Thirty DUWL samples were collected from in use dental units selected randomly from various clinical departments. Samples were collected from the following devices; 3-in-1 syringe waterline, section of waterline tubing supplying the 3-in-1 syringe, and the air rotor water. The samples were subjected to bacteriological analysis, and all bacterial isolates were tested for their ability to form biofilms., Results: A descriptive analysis of the results obtained was carried out, and it was observed that 7 out of 30 (23.3%) samples collected from DUWL were supplying water of unsatisfactory quality with species of low-pathogenicity bacteria isolated present in significant numbers; four of ten (40%) water supply lines contained bacterial biofilms; and the species with greatest capability to form biofilms were Enterobacter species (spp.). In addition, the results were also subjected to Chi-square test which revealed no statistical difference between the species and the location of collection of samples., Conclusion: Within the limitations of this study, it is concluded that DUWLs are not totally free of contamination. Microbial biofilms are a significant source of cross-contamination and cross-infection in the dental clinic environment.

The bacterium Pseudomonas aeruginosa is well known to have a remarkable adaptive capacity allowing it to colonise many environments. A recent study on environmental isolates from dental unit waterlines (DUWLs) hinted at a genetic clustering into two groups. Isolates from one of these groups, named cluster III, were shown to have unusual phenotypes for environmental isolates, such as an increased biofilm production. To have a better ecological view, more specifically on isolates from cluster III, the complete genomes of 39 isolates including 16 from DUWLs were sequenced. In addition to an investigation of antibiotic resistance and secretion system gene content, a molecular phylogeny allowed confirmation of the split of the 16 environmental isolates in two groups and also sheds light on a correlation between the phylogenetic positions and the serotypes of the isolates. Isolates from cluster III harboured insertion sequences ISPa11 inserted into the O-specific antigen biosynthesis clusters and the gene lasR, encoding for a master regulator of the quorum sensing. Investigation of key regulators revealed another truncated gene, gacS. Alteration in lasR and gacS genes was consistent with phenotypic assays confirming their inactivation. These results bring new perspectives regarding the ecological adaptive potential of P. aeruginosa., (© FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Bio-aerosols originate from different sources and their potentially pathogenic nature may form a hazard to healthcare workers and patients. So far no extensive review on existing evidence regarding bio-aerosols is available., Objectives: This study aimed to review evidence on bio-aerosols in healthcare and the dental setting. The objectives were 1) What are the sources that generate bio-aerosols?; 2) What is the microbial load and composition of bio-aerosols and how were they measured?; and 3) What is the hazard posed by pathogenic micro-organisms transported via the aerosol route of transmission?, Methods: Systematic scoping review design. Searched in PubMed and EMBASE from inception to 09-03-2016. References were screened and selected based on abstract and full text according to eligibility criteria. Full text articles were assessed for inclusion and summarized. The results are presented in three separate objectives and summarized for an overview of evidence., Results: The search yielded 5,823 studies, of which 62 were included. Dental hand pieces were found to generate aerosols in the dental settings. Another 30 sources from human activities, interventions and daily cleaning performances in the hospital also generate aerosols. Fifty-five bacterial species, 45 fungi genera and ten viruses were identified in a hospital setting and 16 bacterial and 23 fungal species in the dental environment. Patients with certain risk factors had a higher chance to acquire Legionella in hospitals. Such infections can lead to irreversible septic shock and death. Only a few studies found that bio-aerosol generating procedures resulted in transmission of infectious diseases or allergic reactions., Conclusion: Bio-aerosols are generated via multiple sources such as different interventions, instruments and human activity. Bio-aerosols compositions reported are heterogeneous in their microbiological composition dependent on the setting and methodology. Legionella species were found to be a bio-aerosol dependent hazard to elderly and patients with respiratory complaints. But all aerosols can be can be hazardous to both patients and healthcare workers.

This study is to quantitatively evaluate the efficacy of using a non-contact automatic articulating paper dispenser for reducing microbial articulating paper contamination. Articulating papers in four-handed mode, non-four-handed mode, and via an automatic articulating paper dispenser were evaluated. An adenosine triphosphate bioluminescence assay was used to quantitatively measure the relative light unit (RLU) values of the rest unused articulating papers in the same package to detect contamination at 4 time points, and triplicate examinations were performed for all three methods. The RLUs were recorded, compared, and evaluated. For four-handed mode (n = 36), the RLUs at the four time points were 2.44, 32.89, 37.89, and 27.22, with a satisfactory rate of 94%. The RLUs for non-four-handed mode (n = 36) were 2.22, 286.44, 299.44, and 493.56, with a satisfactory rate of 36%. The RLUs for using the automatic dispenser (n = 36) were all 0 with a satisfactory rate of 100%. The satisfactory rates were significantly different among three methods. No significant differences were observed in the satisfactory rates for the four time points samples. Contact by gloved hands can cause severe biological contamination of articulating paper. However, by using standard four-handed mode or a non-contact automatic articulating paper dispenser, contamination can be controlled.

The perceived threat to public health from dental unit water line (DUWL) contamination comes from opportunistic and respiratory pathogens such as Legionella spp, Nontuberculous Mycobacteria (NTM) and pseudomonads. These organisms can grow and multiply in the DUWL biofilm to reach infective concentrations, with the potential for inhalation leading to respiratory infections or direct contamination of surgical wounds. In this paper we discuss current legislation and practical methods for delivering water within the DUWL that meets the standards for safety. Clinical relevance: Understanding the clinical relevance and methods for decontaminating DUWL is essential to create a safe working environment in dentistry.

Fungi can cause various diseases, and some pathogenic fungi have been detected in the water of dental equipment. This environment offers suitable conditions for fungal biofilms to emerge, which can facilitate mycological contamination. This study verified whether the water employed in the dental units of two dental clinics at the University of Franca was contaminated with fungi. This study also evaluated the ability of the detected fungi to form biofilms. The high-revving engine contained the largest average amount of fungi, 14.93 ± 18.18 CFU/mL. The main fungal species verified in this equipment belonged to the genera Aspergillus spp., Fusarium spp., Candida spp., and Rhodotorula spp. Among the isolated filamentous fungi, only one fungus of the genus Fusarium spp. did not form biofilms. As for yeasts, all the Candida spp. isolates grew as biofilm, but none of the Rhodotorula spp. isolates demonstrated this ability. Given that professionals and patients are often exposed to water and aerosols generated by the dental procedure, the several fungal species detected herein represent a potential risk especially to immunocompromised patients undergoing dental treatment. Therefore, frequent microbiological monitoring of the water employed in dental equipment is crucial to reduce the presence of contaminants.

This study monitored the biodiversity of microbes cultured from a heterogeneous biofilm which had formed on the lumen of a section of dental waterline tubing over a period of 910 days. By day 2 bacterial counts on the outlet-water showed that contamination of the system had occurred. After 14 days, a biofilm comparable to that of clinical waterlines, consisting of bacteria, fungi and amoebae had formed. This showed that the proprietary silver coating applied to the luminal surface of the commercial waterline tubing failed to prevent biofilm formation. Molecular barcoding of isolated culturable microorganisms showed some degree of the diversity of taxa in the biofilm, including the opportunistic pathogen Legionella pneumophila. Whilst the system used for isolation and identification of contaminating microorganisms may underestimate the diversity of organisms in the biofilm, their similarity to those found in the clinical environment makes this a promising test-bed for future biocide testing.

Objective: To determine the current presence of Legionella spp. in the output water of dental unit waterlines (DUWLs) and examine its mitigation by disinfection at the Institute of Dentistry and Oral Sciences, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc., Material and Methods: The first stage of our survey involved collecting samples of DUWL output water from 50 dental chair units (DCUs), and 2 samples of the incoming potable water. In October 2015, a one-time disinfection (1 % Stabimed) of DUWLs was conducted. This was followed by collecting 10 control samples (survey stage 2)., Results: From the total of 50 samples (survey stage 1), 18 samples (36.0 %) tested positive for Legionella spp. Following the disinfection, nine of the ten samples no longer showed any presence of Legionella., Conclusion: Based on culture results, the one-time disinfection (1 % Stabimed) was effective. We are unable to comment on the duration of positive effect of disinfection on the occurrence of Legionella spp. in the outlet water. It was a one-time survey (Tab. 2, Ref. 32).

A high-speed handpiece is used in several dental procedures and the official recommendation for safe decontamination consists of rinsing with water, washing with detergent, mechanical friction, and sterilization; however, many professionals only apply 70% w/v alcohol without also cleaning the tool between patients. We performed an analysis of high-speed handpieces reprocessed only with 70% w/v alcohol and found that the methods used in clinical practice are not safe., (Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Appropriate sanitation procedures and monitoring of their actual efficacy represent critical points for improving hygiene and reducing the risk of healthcare-associated infections. Presently, surveillance is based on traditional protocols and classical microbiology. Innovation in monitoring is required not only to enhance safety or speed up controls but also to prevent cross infections due to novel or uncultivable pathogens. In order to improve surveillance monitoring, we propose that biological fluid microflora (mf) on reprocessed devices is a potential indicator of sanitation failure, when tested by an mfDNA-based approach. The survey focused on oral microflora traces in dental care settings., Methods: Experimental tests (n = 48) and an "in field" trial (n = 83) were performed on dental instruments. Conventional microbiology and amplification of bacterial genes by multiple real-time PCR were applied to detect traces of salivary microflora. Six different sanitation protocols were considered. A monitoring protocol was developed and performance of the mfDNA assay was evaluated by sensitivity and specificity., Results: Contaminated samples resulted positive for saliva traces by the proposed approach (CT < 35). In accordance with guidelines, only fully sanitized samples were considered negative (100 %). Culture-based tests confirmed disinfectant efficacy, but failed in detecting incomplete sanitation. The method provided sensitivity and specificity over 95 %., Conclusions: The principle of detecting biological fluids by mfDNA analysis seems promising for monitoring the effectiveness of instrument reprocessing. The molecular approach is simple, fast and can provide a valid support for surveillance in dental care or other hospital settings.

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.)

There is an unsubstantiated concern as to the health relevance of HPC (heterotrophic plate count) bacteria in dental equipment waterlines. The American Dental Association (ADA) web site includes guidelines for controlling HPC populations and implies that HPC populations >500 CFU/mL as a "health" benchmark. The world-wide published literature including the United Nations fully examined this situation and concluded that HPC bacteria are not a health risk, but merely a general water quality parameter for all waters including dental water lines. This review provides documentation that the standard measurement of HPC bacteria in waters alone do not pose a health risk and the ADA already provides appropriate practices to minimize HPC bacteria in dental equipment water.

Bacterial contamination in dental unit waterlines (DUWLs) was evaluated by molecular techniques in addition to the conventional culture method. Water samples (n=8) from DUWLs were investigated for heterotrophic bacteria by culture method using R2A agar. The selected bacterial antibiotic-resistance genes and Legionella species-specific 16SrDNA were identified by PCR. The profiles of bacterial contamination in DUWLs were further identified by PCR-DGGE. In this study, no antibiotic-resistant or Legionella genes were detected. Polycyclic aromatic hydrocarbon-degrading bacterium, Novosphingobium sp. was the most prevalent in DUWLs. Conventional PCR and PCR-DGGE were shown to be potentially useful for monitoring of bacterial contamination in DUWLs.

Legionella spp. are ubiquitous in aquatic habitats and water distribution systems, including dental unit waterlines (DUWLs). The aim of the present study was to determine the prevalence of Legionella in DUWLs and tap water samples using PMA-qPCR and standard culture methods. The total viable counts (TVCs) of aerobic heterotrophic bacteria in the samples were also determined. Legionella spp. were detected and quantified using the modified ISO 11731 culture method. Extracted genomic DNA was analysed using the iQ-Check Quanti Legionella spp. kit, and the TVCs were determined according to the ISO protocol 6222. Legionella spp. were detected in 100% of the samples using the PMA-qPCR method, whereas these bacteria were detected in only 7% of the samples using the culture method. The number of colony forming units (CFUs) of the TVCs in the DUWL and tap water samples differed, with the bacterial load being significantly lower in the tap water samples (p-value = 0). The counts obtained were within the Italian standard range established for potable water in only 5% of the DUWL water samples and in 77% of the tap water samples. Our results show that the level of Legionella spp. contamination determined using the culture method does not reflect the true scale of the problem, and consequently we recommend testing for the presence of aerobic heterotrophic bacteria based on the assumption that Legionella spp. are components of biofilms.

Background: Dental unit water (DUW) could be contaminated by human pathogens coming from biological fluids penetrated during patient treatment and by opportunistic pathogens detached from aquatic biofilm. These microorganisms could be spread to following patients. We tested the disinfectant activity of hydrogen peroxide and monovalent silver ions (H(2)O(2)-Ag(+)) into DUW artificially contaminated with freshly isolated pathogens., Methods: The tested microorganisms were Staphylococcus aureus, Enterococcus faecalis, Candida albicans, Pseudomonas aeruginosa, Legionella pneumophila, Mycobacterium chelonae, non-pathogenic Bacillus clausii spores. Bacterial suspensions were inoculated into the waterlines of pre-sterilized dental turbines. The test-turbines were connected to DUW and contaminated water was treated for 10 minutes with H(2)O(2)-Ag(+)-based disinfectant (H(2)O(2) 3% v/v, Ag(+) 0.001% w/v). The control-turbines were left untreated. Turbines were washed with sterile hard water used to assess the residual bacterial loads (expressed in colony forming units -cfu). Each strain was tested five times and the mean log loads were assessed. Following the European Standardization Committee, the disinfectant activity was evaluated as mean log load reduction, that is, the difference between the mean log load detected on the control-turbines and the mean log load detected on the test-turbines., Results: Mean bacterial loads detected on the control-turbines ranged between 105-107 cfu. The mean log load reductions resulted 7.5 log cfu for S. aureus, E. faecalis, P. aeruginosa, 6.3 for C. albicans, 5.4 for L. pneumophila, 5.3 for M. chelonae, 2.9 for B. clausii spores., Conclusions: DUW disinfection with H(2)O(2)-Ag(+) could help minimize the risk that planktonic pathogens are spread to patients during dental treatment.