Contamination Of Dental Unit Waterlines Research Articles

A study of different modes of disinfection and their effect on bacterial load in dental unit waterlines

Abstract Objective: To compare the effect of disinfection of dental unit waterlines (DUWLs) on bacterial load using disinfection methods and agents like 0.12% chlorhexidine gluconate (CHX), time-dependent flushing (1 min, 2 min), and using distilled water and tap water as water sources. Materials and Methods: Four dental units were taken: Unit A contained 0.12% CHX, Unit B contained distilled water, Unit C contained tap water, and Unit D included flushing for 1 and 2 min. A total of 36 water samples were collected in 2 weeks. One sample of tap water from basin was taken as study control. One sample each from Unit A, B, and C and 2 samples from Unit D (1 min and 2 min flushing) were taken as baseline samples. Samples were collected three times a week and assessed for total viable count (TVC) and types of organisms present. Results: For Unit A, no growth of microorganisms was observed. Flushing for 1 min and 2 min showed variable TVC. No significant difference was seen in TVC of units B, C, and D in comparison to the baseline samples. Conclusions: It was found that 0.12% CHX was very effective in controlling DUWL contamination. Adhering to a recommended 2 min flushing regimen can reduce the bacterial counts, but is not a reliable means of disinfection.

Microbial contamination of dental unit waterlines in dental practices in Hesse, Germany: A cross-sectional study.

The quality of water from dental units is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. This study analyzed the microbial quality of water obtained for periodical monitoring from 56 dental units in different dental practices in Hesse. Contamination by Legionella spp., Pseudomonas aeruginosa, and increased total colony counts were detected in 27.8%, 3.5%, and 17% of samples. Legionella pneumophila serogroup 1 accounted for 28% of Legionella isolates. The Legionella concentration was >100 cfu/100 ml in 84% of contaminated samples. Samples collected from an instrument channel were more frequently contaminated by Legionella than those from cup filler (41.7% vs. 18.6%, p = 0.02). After release of these results, decontamination measures were performed in units that had revealed unsatisfactory results. The outcome of the intervention was followed-up by microbiological analysis. At follow-up, 65.2% and 72.7% of waterlines that had previously been contaminated by Legionella or had shown increased total colony counts were free of contamination. Our results show a high rate of contamination of water from dental units in dental practices in Hesse. They highlight the risk of exposure for patients and personnel and the need for effective strategies to reduce microbial contamination.

Disinfection of Dental Unit Water Line Using Aloe Vera: In Vitro Study

Context. Dental unit waterlines may be heavily contaminated with microorganisms and are a potential source of infection for both practicing staff and immunocompromised patients particularly. Contamination of dental unit water lines could be inhibited with the use of disinfectants. The present study investigates the effect of aloe-vera-based disinfectant in reducing the microbial growth in dental unit water lines (DUWLs). Aims. To compare the efficacy of aloe vera, hydrogen peroxide (H2O2), and 5% sodium hypochlorite (NaOCl) in controlling microbial contamination of DUWLs. Materials and Methods. After obtaining baseline water samples, the dental unit waterlines were treated with aloe vera, 10% hydrogen peroxide, and 5% sodium hypochlorite. Each of the three disinfectants was used in increasing concentrations and their inhibiting effect was compared. Water samples were analyzed for microbiological quality by the total viable count (TVC) method. Statistical Analysis Used. SPSS 16. Results. There was significant reduction in mean CFU/ml when treated with disinfectants each for a period of one week. Aloe-vera solution was found to be the most effective in reducing the microbial colonies. Conclusions. Improving the water quality from dental unit water lines is of considerable importance; chemical-based disinfectants can be replaced with herbal disinfectants for treating microbial contamination in dental unit waterlines.

Quality of air and water in dental healthcare settings during professional toothcleaning

Introduction. Professional toothcleaning with ultrasonic scaler produces microbial aerosols. These microorganisms come from dental unit waterlines (DUWLs) -thus potentially including opportunistic pathogens, or from patients -thus potentially including human pathogens. Aim. To investigate the association between levels and quality of contamination of air samples and DUWLs during professional toothcleaning, thus providing information regarding the nature of air contamination produced by ultrasonic scaler use. Material and methods. Before treating the first patient of the day, 100 mL of water was aseptically collected from the DUWL designated for the ultrasonic scaler, water was not disinfected or flushed. Aliquots were plated on Plate Count Agar to determine total viable flora (TVF) and Charcoal-Yeast Extract Agar supplemented with α Growth Supplement to determine Legionella. Two sets of settle plates were placed on the tray in front of the patient, one before and another during patient treatment to determine TVF and Legionella. The association between TVF and Legionella levels and prevalence in DUWLs and in air samples was assessed using correlation coefficients. Results. 82 testing occasions were performed. The mean TVF levels in DUWLs and air were 21.2 (95% confidence interval, 95CI, 13.8-32.6) CFU/mL and 12.4 (95CI, 9.7-15.8) CFU/plate/h, respectively. The mean Legionella detection rates were 1.2% (DUWLs) and 0% (air). Correlations between air and water TVF and Legionella were not significant. Conclusion. Air contamination during ultrasonic scaler use was frequent and high, but it was not associated with DUWL contamination, suggesting that airborne microorganisms could come from patients and be potentially pathogens for humans.

Mechanized scaling with ultrasonics: Perils and proactive measures

Mechanized scaling for plaque removal is a routine procedure in the practice of periodontics. Though it appears innocuous by itself, there are retinues of hazards associated with it on various organ systems in the body. Some of these unwanted effects and measures to avoid or ameliorate the same are elaborated here. Exposure to ultrasonic scaling is inevitable before any other treatment procedure. Aerosol contamination, vibrational hazards, thermal effects on the dental pulp, altered vascular dynamics, disruption in electromagnetic device, diminished hearing and dental unit waterline contamination are some of the probable off-shoots a patient has to bear. Uses of barrier devices, proper attention to usage of equipment, protection for ear and water treatment are few of solutions for the same. Though documented evidence for the existence of all effects is lacking, it is never the less significant for the overall safety of the patient. A conscientious clinician should therefore inculcate the available steps to overcome the hazards of ultrasonic scaling.

EVALUATION OF ACTIVITIES AIMED AT PREVENTING MICROBIOLOGICAL RISKS IN DENTAL PRACTICE

Microbiological contamination of water in dental unit waterlines (DUWL) creates a risk of cross-infections, and is a source of biological risk factors in the work environment of a dentist. The aim of the study was to evaluate dentists' knowledge on DUWL microbiological contamination and the scope of activities/procedures they undertake to monitor it. The questionnaire survey was conducted in 2010 among 107 Polish dentists using dental units in everyday clinical practice. It has been found that in their daily practice, dentists do not follow procedures leading to reduction or elimination of microbiological contamination of dental unit reservoir water. They are not aware of microbiological contamination of DUWL that supply working handpieces with water. They are unaware of the principles of dealing with dental water and water supply systems or the health risk posed by microbiological contamination of unit water for a dental team and patients. It is necessary to provide dentists with information on microbiological contamination of water in dental units, on the correct procedures of handling water and waterlines that supply working handpieces with water.

Dental unit water lines: The infectious sources of Pseudomonas aeruginosa

Water quality in the dental unit water lines (DUWLs) is important to the patients and dental healthcare personnel as they are at risk of being infected with Pseudomonas aeruginosa. The aim of the present study was to determine the occurrence of P. aeruginosa contamination in DUWLs and to study the antibiotic resistant profile. A total of 101 dental water samples including air/water spray (26), Ultrasonic scalar (24), Air rotor compressor (26) and Distilled water (25) were screened for P. aeruginosa and 67 samples were found to be contaminated by P. aeruginosa. All these isolates were further subjected to antibiotic susceptibility testing. Among these, 63 (94.02%) showed resistance to ampicillin followed by 39 (58.20%) to amoxicillin, 11 (16.41%) to cefepime, 5 (7.46%) to aztreonam and 1 (1.49%) to gentamicin.

Bacterial contamination of dental unit waterlines

Safety of patients and dental personnel requires the appropriate microbiological water quality in dental units. During treatment, patients and dental workers are exposed both to direct contact with bacteria-contaminated water in the form of splatter and with contaminated water aerosol emitted during work by unit handpieces, including rotating and ultrasonic instruments. The aim of the study was to determine the qualitative and quantitative contamination of water in dental unit reservoirs with aerobic and facultative anaerobic bacteria. The study material included water sampled from 107 dental unit reservoirs located in dental surgeries of public health centres. Conventional microbiological methods were used to identify microorganisms. The study shows that the contamination of water in dental unit reservoirs with aerobic and facultative anaerobic bacteria is commonplace. The mean concentration of mesophile bacteria in dental unit reservoir water exceeded 1.1 × 105 cfu/ml. The prevailing species were Gram-negative bacteria of the families Burkholderiaceae, Pseudomonadaceae, Ralstoniaceae and Sphingomonadaceae. The most numerous bacteria were Ralstonia pickettii, constituting 49.33 % of all the identified aerobic and facultative anaerobic bacteria. Among Gram-positive rods, the most numerous were bacteria of the genus Brevibacterium (5.83 %), while the highest percentage shares (13.25 %) of all Gram-positive microorganisms were found for Actinomyces spp. The study confirms the necessity of regular monitoring of microbial contamination of dental unit waterlines (DUWL) and use of various water treatment procedures available to disinfect DWUL.

Update on infectious risks associated with dental unit waterlines

Modern dental chair units consist of a network of interconnected narrow-bore plastic tubes called dental unit waterlines (DUWLs). The water delivered by these DUWLs acts as both a coolant for a range of instruments and an irrigant during dental treatments. The quality of water is of considerable importance because both patients and dental team are regularly exposed to water and aerosols generated by dental equipment. Studies have demonstrated that DUWLs provide a favourable environment for microbial proliferation and biofilm formation, and that water is consequently often contaminated with high densities of various microorganisms (bacteria, fungi, protozoa, viruses). The presence of high levels of microbial contamination may be a health problem for dentists and patients, especially those who are immunocompromised. The current status of knowledge on microbial contamination of DUWLs is presented, with an emphasis on the infectious risk associated with DUWLs and on the various approaches for disinfecting and protecting DUWLs.

Impact of cleaning regimes on dental water unit contamination

Microorganisms that have been identified in dental unit waterlines (DUWLs) are of concern because they can cause infections, especially in immunocompromised patients. This study aimed to assess the incidence of microbial contamination in DUWLs before and after intervention to reduce contamination, and to investigate the presence of coliforms, Escherichia coli and Pseudomonas aeruginosa. Water samples were collected aseptically from the waterlines. The high-speed hand-piece and dental chair units were served by one distillation apparatus, which was fed by the potable tap water of four dental clinics. Different interventions were used: chlorination, flushing before clinics and between patients, draining at the end of the day, and freshly distilled water on a daily basis. There was a significant difference between the level of contamination in the high-speed hand-piece (1.5-2.7 log CFU/ml) and dental chair unit water (2.0-3.5 log CFU/ml). Coliforms (0.9%) E. coli (0.9%) and Pseudomonas (1.8%) were detected during 2008. This study indicates the need to monitor water quality regularly and prevent stagnation in DUWLs to reduce the number of viable bacteria to <100 CFU/ml. We recommend flushing the DUWL for 2 min before the first patient and for 10-20 s between patients, flushing the dental unit at the end of the day and draining it overnight to reduce the development of biofilms, and chlorination of the DUWLs.

Biofilm, dental unit water line and its control

Biofilms are well-organized communities of cooperating microorganisms that can include bacteria, algae, fungi and diatoms. Dental unit waterlines (DUWL) are an integral part of dental surgery equipment, supplying water as a coolant, primarily for air turbine and ultrasonic scalers. Surveys of dental unit waterlines (DUWLs) indicate that biofilm formation is a universal problem and great majority of bacteria that have been identified from DUWL are ubiquitous, although present in only low numbers in domestic water distribution systems, but can flourish as biofilms on the lumen surfaces of narrow-bore waterlines in dental units. DUWL contamination and its significance as a factor in nosocomial infection of patients and health care workers has stressed the risk to immunocompromized persons. Not only patients but also dentists and dental personnel are at risk of being infected with opportunistic pathogens such as Pseudomonas or Legionella species by means of cross-infection or after aerosol formation from water emanating from DUWL. Several methods of decreasing the level of contamination in DUWL have been proposed. At present, the goal of this review is to discuss various aspects of biofilm formation and effective standardized disinfecting methods to maintain low bacterial counts in dental water line. This will increase the awareness of potential health risks posed by biofilm formation and provide information on techniques and devices designed to control the microbial contamination of DUWLs.

Effect of 70% alcohol swabbing and flushing technique on high speed contra angle towards bacterial count and identification of pathogens

High-speed contra angle is a potential source of cross-infection due to its working system in blowing up water, saliva and microorganisms from the patients, as well as dental unit water line contamination. This experimental Quasy laboratory study aimed to determine the reduce of bacteria in high-speed contra angle after 70% alcohol swabbing and flushing for 30 seconds and identifying the presence of the pathogen. This study was conducted on 35 lower molar teeth with caries without abscess in patients during pulp opening with the contra-angle. Afterwards, the contra-angle was immersed in sterile aquadest and flushed. The immersed and flushed water were sampled then cultured on blood agar plates. The colony forming units were counted manually: Group I, was the control; Group II, after used on patients; and Group III, after treatment and swabbed with 70% alcohol and flushed. The data were statistically analyzed according to Anava and continued by test with least significant differences (LSD). The results showed that in bacterial identification there were pathogens. The bacteria amount was reduced after swabbing the contra-angle from 50.88±40.33 to 10.31±20.02 cfus. After flushing, the cfus decreased from 169.74±53.76 to 73.03±36.39. Based on the variant and LSD analyzes (p&lt;0.01), CFU was significantly different among the three groups. Conclusion: 70% alcohol swabbing and flushing could reduce the bacterial amount in high-speed contra angle and there was the presence of Staphylococcus aureus and Pseudomonas aeruginosa on the usage of high-speed contra-angle.

Characterization Of Biocides Resistant Isolates From Dental Unit Water Line Biofilms By Culture Dependent Approach

The importance of biocides resistant bacterial strains in medicine, industry and the environment has gained significant attention. Microbial contamination of dental unit waterlines is thought to be the result of biofilm formation within the small-bore tubing used for these conduits. Our objectives were to characterize biocides resistant isolates from dental unit water line biofilm (DUWL) using the standard laboratory approaches. Growth curves of isolates established in biocides free and supplemented medium demonstrated less growth in the presence of biocides. O10 | P a g e ptimum pH was 7 whereas; optimum temperature was 37°C. Isolates showed resistance against multiple of heavy metals while fewer antibiotics. Genetic studies were accomplished by performing conjugation and transformation experiments. In two isolates (AWT 21 and PTNPF) transconjugants were observed, while no transformant was recorded in any case. Overall, the findings of this study can be used to profile the metabolic effects of new biocides or biocide combinations upon biocidesresistant biofilm isolates from clinical environment.

Specific Anti Cross-Infection Measures may Help to Prevent Viral Contamination of Dental Unit Waterlines: a Pilot Study

In recent years, several reports have suggested, but never definitely demonstrated that dental units (DU) could be potential sources of viral cross-infections sustained by viral agents including HBV, HCV and HIV. This work aims at assessing the risk of HCV cross-infection by dental unit water lines (DUWLs). Ten anti-HCV positive viremic patients were submitted to dental treatment on three different DU (one unit fully equipped to minimize viral contamination risk). A PCR method using primers for UTR and E2 regions was used to evaluate HCV RNA presence in DUWLs sprays. A modified RNA extraction protocol was developed to eliminate the risk of low sensibility due to the presence of inhibitors in saliva. Sequences obtained from E2 PCR products amplified from blood and oral fluids were analyzed and compared. Fluids collected from three different DU before treatment were always negative for the presence of HCV RNA; after treatment viral contamination was detected in six out of ten cases in conventional DU, in three out of ten cases on the reduced-retraction DU while was never detected in sprays taken from fully equipped DU. Comparison of E2 region sequences obtained from blood and DUWLs sprays showed identity in each patient. Here we demonstrate that fixed DUWLs and handpieces can be contaminated by viral agents and become a vehicle of cross-infection and that a specific online active decontamination system developed for both handpieces and fixed waterlines can eliminate this risk.

The influence of dental unit waterline cleaners on composite-to-dentin bond strengths

One approach to controlling dental unit waterline (DUWL) contamination by microorganisms is the addition of chemical cleaners to the treatment water. Yet, there is concern that these cleaners might affect the bonding of resin-based composites to enamel and dentin. The authors evaluated the influence of DUWL cleaners on composite-to-dentin bond strengths. The authors tested the strength of resin-based composite bonded to dentin in specimens treated with distilled water (control) or one of four cleaners. They tested a total-etch adhesive, a self-etching primer/adhesive and an experimental self-etching primer/adhesive. The authors stored the specimens for 24 hours at 37 C and tested them to determine their bond strengths. The mean shear bond strengths (SBSs) varied according to the cleaner and adhesive used, ranging from 14.7 to 21.9 megapascals. However, the authors found no statistically significant differences and/or interactions between mean SBSs of specimens treated with the various DUWL cleaners and adhesives (P > or = .05). The tested DUWL cleaners did not significantly influence composite-to-dentin bond strengths for the total-etch adhesive and self-etching primer/adhesives used in this study. The conclusions imply that bonding of resin-based composites to dentin is not affected by the cleaners tested when they are used to treat DUWL contamination.

Management of dental unit water lines

While the number of proven cases of infection from dental unit water lines (DUWL) is limited, exposure to water of poor microbiological quality is inconsistent with expectations of safety standards in modern dentistry. In this article, Caroline Pankhurst details methods for preventing DUWL contamination and tips for everyday management.

Detection and Quantification of Dental Unit Water Line Contamination by Oral Streptococci

(1) To investigate the prevalence of oral streptococci (OS) and biological indicators of water contamination by oral fluids in water from dental unit water lines (DUWs) by detection and quantification and of saprophytes indigenous to the oral cavity. (2) To test whether measurement of the total cultivable mesophilic flora (TCF), the parameter commonly used to monitor water quality in DUWs, is an effective predictor for OS contamination. Survey of 21 dental units equipped with antiretraction devices. Water samples were collected from air-water syringes, cup fillers, tap water, and before and during the working day. Units were from 7 public dental offices selected for convenience from among those in proximity of the microbiological laboratory. For detection of OS, samples were plated on an enriched medium, to revitalize the organisms. Colonies were subcultured on a selective medium and biochemically identified (lower detection limit, 1 cfu/mL). For measurement of the TCF, samples were plated on a nutrient-poor medium. Cultures with colony counts greater than 200 cfu/mL were considered to be TCF positive. The sensitivity and specificity of TCF positivity in predicting OS detection was calculated. Prevalence rates for OS contamination and for TCF positivity were, respectively, 34.4% (11 of 32 samples) and 25.0% (8 of 32 samples) for syringes, 27.8% (10 of 36 samples) and 8.3% (3 of 36 samples) for cup fillers, and 0.0% (0 of 7 samples) for tap water. OS contamination levels ranged from 1 to 6 cfu/mL. No statistically significant differences were found between samples obtained before and during the working day. TCF positivity did not predict OS contamination effectively, because of low sensitivity. Given the absence of OS in tap water, the reported prevalence of OS contamination suggests that oral fluids are aspirated during dental therapy with relatively high frequency and that DUWs can potentially expose successive patients to bloodborne cross-infections.

Changing face of infection control: Dental unit water lines

The quality of dental unit water is of considerable importance since patients, staff are regularly exposed to water and aerosols generated from the unit. The contamination of dental unit waterlines (DUWL) is an issue that is of great concern to the dental profession, including Prosthodontics since the water in these lines has the capacity for rapid development of biofilms combined with the generation of potentially contaminated aerosols becoming an ideal environment for the growth of microorganisms. This article describes the conditions in waterline tubing that favour development of biofilms and discusses the level of risk that such microbial growth poses for both dental professionals and their patients. It is stressed that very few cases of infection have been linked directly to contamination in dental unit waterlines. Finally, potential solutions for minimizing risks are presented and discussed.

The effect of washing water on bonding to etched enamel.

There is current concern about bacterial contamination of dental unit waterlines. This research hypothesized that the presence of increasing concentrations of bacteria in water used to wash etched enamel would result in a corresponding decrease in both shear bond strength (SBS) and critical surface tension (gammaC) of enamel. A further hypothesis was made that there is a correlation between SBS and gammaC. The effect of 3.5 ppm iodine in the water as a bacteriostatic agent was also assessed. Five groups of 10 samples of bovine enamel were etched, washed, and a resin composite bonded to them. The control group was washed with distilled water. Another group was washed with the dilute iodine solution. The remaining three groups used a different concentration of Escherichia coli DH5alpha as follows (in cfu mL(-1)): group 1: 10(2); group 2: 10(4); group 3: 10(6). Shear bond strength data were measured on an Instron testing machine at a crosshead speed of 1 mm min(-1). Adhesion data were (MPa): control: 24.6 +/- 6.0; with iodine: 20.8 +/- 2.7; group 1: 19.8 +/- 2.7; group 2: 13.5 +/- 3.0; group 3: 13.9 +/- 3.6. The F-test yielded a highly significant difference between control group, iodine group and group 1, compared with groups 2 and 3 (P < 0.0001). Tukey's Studentized Range Test was used for pairwise comparison testing between groups. Using a Cahn dynamic contact angle analyzer and linear regression analysis, the plots of surface tension versus costheta were extrapolated to costheta = 1 to give gammaC data for the control group and groups 1-3. In all cases reasonable linearity was observed (r2 > or = 0.87). Data (mN m(-1)) were: control group: 50.8; group 1: 45.1; group 2: 43.2; group 3: 39.5. The SBS and gammaC were then plotted against each other and linear regression analysis performed. It was concluded that increasing concentrations of bacteria in wash water decreased both SBS and gammaC and that a linear correlation (R2 = 0.84) was found between the values of these two parameters.

Microbial contamination in dental unit waterlines.

The quality of water in a dental unit is of considerable importance because patients and dental staff are regularly exposed to water and aerosol generated from the dental unit. The aim of this study was to evaluate the occurrence of microbial contamination in dental unit waterlines. Water samples were collected aseptically from the waterlines (reservoir, triple-syringe, high-speed) of 15 dental units. After serial dilution to 1:10(6) in APHA, the samples were seeded by the pour-plate technique and cultured in plate count agar (Difco) for 48 h at 32 degrees C. Analysis was based on the number of colony forming units (CFU). The Wilcoxon non-parametric test indicated that the levels of water contamination were highest in the triple-syringe (13 of 15) and in the high-speed (11 of 15); both levels were higher than those of the water reservoir. There was no significant statistical difference between the level of contamination in the triple-syringe and the high-speed as determined by the Mann-Whitney test [p(H0) = 40.98%; Z = - 0.2281]. Because biofilm forms on solid surfaces constantly bathed by liquid where microorganisms are present, these results indicate that the water in the dental unit may be contaminated by biofilm that forms in these tubules.