Dental Unit Water Research Articles

Detection and Quantification of Bacterial Flora in Dental Unit Water Systems and the Effect of Flushing on its Reduction

Statement of Problem: The origin of Dental Unit Water Lines (DUWL) contamination is specially related to the formation of biofilm which is com­posed of microorganisms within water and is located on the tubing lines. Purpose: In this descriptive study, we evaluated the degree of contamina­tion with Gram positive and Gram negative bacteria in DUWLs of the dent-al school and also determined the efficacy of flushing on reducing its micro­bial count. Materials and Methods: Thirty dental units from all the departments of de­ntal school in Tehran University of Medical Sciences were selected for this study. Sampling consisted of a two step procedure before and after one min­ute of flushing. The samples were taken from air/water line of each selected dental unit separately. Air/water syringe of each unit was completely disinf­ected with Deconex before sampling. Results: The range of the contamination varied from190 to 23 ×10 5 CFU/ml. The bacterial contamination included anaerobic Gram negative bacilli, non-fermenting Gram negative bacteria, Gram positive cocci and Gram positive bacilli. In all the samples taken from water taps, contamination was noted, varying from 25 to 1700 CFU/ml. This was significantly lower than the co­ntamination of air/water syringe of the dental units. Conclusion: Applying the right principles for infection control such as using disinfectants or sterile water in dental settings and daily flushing before visit­ing patients can be of great significance. KEY WORDS: Dental unit; Water line; Bacterial contamination; Flushing

Ozone therapy in dentistry: A literature review

This review of literature is an attempt to summarize different modalities of ozone application in dentistry. Ozone gas has a high oxidation potential and is effective against bacteria, viruses, fungi, and protozoa. It also has the capacity to stimulate blood circulation, platelets, and immune response. Ozone is used in dentistry in gaseous, ozonated water and as ozonated oils. Ozone was shown to be biocompatible and is used in all aspects of dentistry. It has been shown to stimulate remineralization of recent caries-affected teeth and is used as a preventive therapy in caries, root caries, and intracanal irrigants in endodontic treatment. It has been used in treatment of alveolitis, avascular osteonecrosis of the jaw, and herpes virus infection. It also inhibits plaque formation and can be used as an adjuvant in periodontal surgical and maintenance phase. Ozone has also been used in dental unit water line to disinfect water. Advantage of ozone therapy is it is an atraumatic, biologically based treatment. While laboratory studies suggest a promising potential of ozone in dentistry, less number of clinical studies were documented. More number of randomized, controlled trials need to be conducted to determine the precise indications and guidelines to treat various dental pathologies with this promising medical agent.

Evaluation of Two Methods in Controlling Dental Treatment Water Contamination

Dental unit water systems are contaminated with biofilms that amplify bacterial counts in dental treatment water in excess of a million colony forming units per milliliter (cfu/ml). The Centers for Disease Control and Prevention and the American Dental Association have agreed that the maximum allowable contamination of dental treatment water not exceed 500 cfu/ml. This study was conducted to evaluate two protocols in controlling contamination of dental unit water systems and dental treatment water. Both methods used an antimicrobial self-dissolving chlorine dioxide (ClO₂) tablet at a high concentration (50 ppm) to shock the dental unit water system biofilms initially followed by periodic exposure. To treat dental treatment source water for patient care, 3 parts per million (ppm) ClO₂ in municipal/tap water was compared to use of a citrus botanical extract dissolved in municipal water. Heterotrophic microbial counts of effluent water and laser scanning confocal microscopy were performed to evaluate effects of the two treatments. Results from this study indicated that both treatments were effective in controlling biofilm contamination and reducing heterotrophic plate counts <500 cfu/ml. A comprehensive study addressing compatibility of 50 ppm ClO₂ on the metals and nonmetal components of the dental water system and effects of low-grade chemicals used on composite bonding to dentin and enamel is warranted before translation from efficacy studies to common clinical use. This study provides evidence-based information of using two methods of controlling dental treatment water contamination. The study was conducted in a clinical practice setting in an active dental clinic and the results are meaningful to a clinician who is interested in providing safe dental treatment water for patient care. Dental waterline biofilms, Dental treatment water contamination control, Chlorine dioxide, Emulsifiers, Heterotrophic plate counts, Laser scanning confocal microscopy. How to cite this article: Bansal R, Puttaiah R, Harris R, Reddy A. Evaluation of Two Methods in Controlling Dental Treatment Water Contamination. J Contemp Dent Pract 2011;12(2):73-83. Source of support: Nil Conflict of interest: None declared.

Evaluation of gram negative bacterial contamination in dental unit water supplies in a university clinic in tabriz, iran.

Background and aims Bacterial contamination of dental unit water supplies (DUWS) has attracted a lot of attention in recent years due to the emergence of serious infectionsin susceptible dental patients. The aim of the present study was to evaluate the presence of gram-negative bacterial contamination in DUWS at Tabriz University of Medical Sciences Faculty of Dentistry. Materials and methods This descriptive study was carried out on 51 active dental units in different departments. Con-tamination was determined by taking samples from the unit's water supply before dental procedures and the use of specific culture media. The cultures were evaluated after 48 hours. Results Gram-negative bacterial contamination was identical in all the departments. In the departments on the ground floor, namely Departments of Periodontics and Oral and Maxillofacial Surgery, Pseudomonas contamination was observed in 71% of units; in the departments on the first floor, namely Departments of Prosthodontics, Orthodontics and Pedodon-tics, 46.8% of the units had Pseudomonas contamination; and in the departments on the second floor, namely Departments of Operative Dentistry and Endodontics, 37.7% of the units demonstrated Pseudomonas contamination. Conclusion Gram-negative bacterial contamination was evident in the evaluated DUWS. The contamination type was identical but the number of contaminated units decreased with the increase in the height of the floors.

Effects of Hydrogen Peroxide on Dental Unit Biofilms and Treatment Water Contamination

To study effects of various concentrations of hydrogen peroxide on mature waterline biofilms and in controlling planktonic (free-floating) organisms in simulated dental treatment water systems; and to study in vitro the effects of 2%, 3%, and 7% hydrogen peroxide on the removal of mature biofilms and inorganic compounds in dental waterlines. Four units of an automated dental unit water system simulation device was used for 12 weeks. All units were initially cleaned to control biofilms and inorganic deposits. H2O(2) at concentrations of 1%, 2%, 3% was used weekly for periodic cleaning in three treatment group units (units 1, 2 & 3), with 0.05%, 0.15% and 0.25% H(2)O(2) in municipal water used as irrigant respectively. The control unit (unit 4) did not have weekly cleanings and used municipal water as irrigant. Laser Scanning Confocal Microscopy and Scanning Electron Microscopy were used to study deposits on lines, and weekly heterotrophic plate counts done to study effluent water contamination. A 24 hour in vitro challenge test with 7%, 3% and 2% H(2)O(2) on mature biofilms was conducted using harvested waterlines to study biofilm and inorganic deposit removal. Heterotrophic plate counts of effluent water showed that the control unit reached contamination levels in excess of 400,000 CFU/mL while all treatment units showed contamination levels <500 CFU/mL through most of the 12 weeks. All treatment units showed varying levels of biofilm and inorganic deposit control in this short 12 week study. The in vitro challenge test showed although there was biofilm control, there was no eradication even when 7% H(2)O(2) was used for 24 hours. 2% H(2)O(2) used as a periodic cleaner, and diluted to 0.05% in municipal water for irrigation was beneficial in controlling biofilm and planktonic contamination in dental unit water systems. However, to remove well established biofilms, it may take more than 2 months when initial and multiple periodic cleanings are performed using H(2)O(2).

Evaluation of a New Dental Unit Water Line Cleaning System

Evaluation of a New Dental Unit Water Line Cleaning System

Effects of Iodine in Microbial Control of Dental Treatment Water

To determine the effects of low levels of iodine constantly present in the dental unit water system on microbial control of dental treatment water and biofilm control. This study used a dental unit water system simulator with eight dental unit waterline systems built to scale and function, each controlled via computer. Each of the eight units was operated independently, four units supplied with self-contained water reservoirs and four units supplied with municipal water. Four units were precleaned to remove biofilm buildup. The study had a well-balanced design with equal representation (variables) of presence/absence of biofilms, selfcontained reservoirs for introduction of treatment water, source water directly connected to municipal water source and iodinated cartridges within the self-contained reservoirs and between municipal water and dental unit. Point-of-use iodinated resin cartridges (IRC) were retrofitted proximal to handpiece and air/ water syringe tip lines in four units, and iodinated resin water cartridges (IRSWC) were fitted to the other four units at the source water output. Heterotrophic plate counts were performed at baseline and twice weekly for a period of 6 weeks. One representative waterline sample was taken from each group at baseline and end-of-study to analyze changes in biofilm status using scanning electron microscopy. Waterlines not previously contaminated with biofilms did not show organization of biofilm matrix in units equipped with IRSWC. Constantly present low levels of iodine, demonstrated some disruption of biofilms in waterlines already contaminated with mature biofilms. All groups showed contamination levels < 500 cfu/ml (colony forming units per milliliter) consistent with the CDC and ADA guidelines. In this 6 weeks study, IRSWC equipped waterlines showed disruption of established biofilms, controlled formation of new biofilms in clean lines and rendered the dental treatment water < 500 cfu/ml. Point-of-use iodinated resin cartridges were also effective in controlling contamination in the dental treatment water. Dental unit water systems that are in use get contaminated with microbes and biofilms in weeks of being put into use. These biofilms contaminate the treatment water thereby putting patients and staff at risk of infection by predominantly gram-negative microbes. Biofilms in the water systems must be cleaned periodically with a strong decontaminant and the dental treatment source water needs to be modified with a low-grade antimicrobial that can preserve the water quality yet safe to humans. In this translational research study, we evaluate the effects of elemental iodine dissolved in water flowing through an iodine containing cartridge in controlling biofilm and dental treatment water contamination using a dental unit water system simulator, prior to clinical utilization.

Improving dental unit water quality through audit

Chate RA (2010) An audit improves the quality of water within the dental unit water lines of general dental practices across the East of England. Br Dent J 209(7): E11

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.

P11.08 The effect of a mobile air purification unit on the air quality of a room contaminated with Aspergillus sp.

P11.08 The effect of a mobile air purification unit on the air quality of a room contaminated with Aspergillus sp.

An audit improves the quality of water within the dental unit water lines of general dental practices across the East of England

To evaluate and improve upon the quality of water emanating from the dental unit waterlines (DUWLs) which supply irrigation for dental handpieces and triple spray syringes in general practice. A prospective clinical audit. Seventy-two general dental practices in the East of England. In 2006, 124 dentists initially registered to participate in the audit. By 2007, 72 had begun and by 2008, 68 had completed the project. This involved collecting samples of water discharged from the DUWLs in the dental practices both before the start and mid-way through a morning session. These were tested microbiologically at a United Kingdom Accreditation Service testing laboratory. Before the audit, 56% of the DUWLs were reportedly flushed through for 2 minutes at the start of the day, 29% were purged for 20 seconds in between each patient, 50% were treated with a wide range of different disinfectant solutions, 44% were drained down dry at the end of the day and 9% had no cross-infection control measures applied to them at all. In the audit, 100% used a disinfectant solution alone, predominantly either Alpron or Sterilox. The minimum audit standard set was for the water samples to meet the United States' Centers for Disease Control and Prevention (CDC) guideline on the quality of DUWL water, namely that the United States' Environmental Protection Agency (EPA) regulatory standards for drinking water be adopted, in that no more than 5% of water samples should be contaminated with total coliforms and that they should not have more than 500 colony forming units per ml (cfu/ml) of heterotrophic water bacteria. However, the participating dentists were encouraged to try and achieve the more stringent European Union (EU) standards for potable (drinking) water, namely for the water samples to have neither Escherichia coli nor any other faecal coliforms present and for the aerobic colony count to be less than 100 cfu/ml at 22°C after 72 hours of culturing. In the pre-audit survey, none of the 72 DUWL water samples were contaminated with E. coli but in five of them (7%) coliforms were recovered. Only 25% reached the EU potable water standard, of which 11% had zero planktonic bacterial contamination. Three percent were above the EU standard but below the CDC guideline/EPA regulatory drinking water standard, while alarmingly, 72% of them failed to reach this minimum audit standard altogether. However, after the application of a suitable disinfectant for at least a month, the audit revealed that E. coli still remained absent in the water samples taken from the 68 DUWLs that completed the project and in only one (1.5%) were coliforms recovered. Remarkably, nearly 81% reached the EU potable water standard, of which 54% had zero planktonic bacterial contamination, with nearly an additional 6% reaching the American CDC/EPA standard and with only 13% failing outright. Clinical audit using appropriate DUWL disinfectants can result in the improvement of the quality of water that is discharged through DUWLs, thereby minimising both the risk of cross-infection to vulnerable patients as well as to dental staff chronically exposed to contaminated aerosols.

P11.09 Water microfiltration at the point of use – a procedure to prevent infection/colonization with water borne pathogens in ICU patients?

P11.09 Water microfiltration at the point of use – a procedure to prevent infection/colonization with water borne pathogens in ICU patients?

Summary of: An audit improves the quality of water within the dental unit water lines of general dental practices across the East of England

Summary of: An audit improves the quality of water within the dental unit water lines of general dental practices across the East of England

Evaluation of Antimicrobial-Antibiofilm Activity of a Hydrogen Peroxide Decontaminating System Used in Dental Unit Water Lines

A dental unit water line (DUWL) equipped with a device designed to automatically and continually flush a bacteriostatic solution of hydrogen peroxide (WHE) and a discontinuous disinfecting system (BIOSTER) was evaluated. In the first instance a preliminary sensitivity test on a large number of microorganisms (bacteria and fungi) was tried with a H2O2 range from 100 to 800 ppm. The bacteria frequently reported in DUWL (including Pseudomonas spp, Streptococcus spp., Staphylococcus spp., E. coli) and some periodontal pathogens showed a minimum inhibitory concentration from 100 to 300 H2O2 ppm (also including M. marinum and C. albicans). However, H2O2 did not show any inhibitory effects against: A. actinomycetemcomitans, C. glabrata C. parapsilos, F. nucleatum, M. micros. In a second step, the DUWL was experimentally infected with S. faecalis, E. coli, P. aeruginosa, S. aureus. After disinfection steps with 3% H2O2, the inhibitory effect on planktonic forms and on sessile biofilm was measured. In a third step, the count of 16S rRNA gene copies by real time PCR at different points of the DUWL described an accrue of bacterial slime in “hot spot” regions characterized by irregular/slow water flux (valves, elbows). However these results suggest that hydrogen peroxide is not only able to inhibit bursts of planktonic bacteria inside the DUWL, but that it could also be effective against sessile biofilm containing heterotrophic microorganisms derived from domestic water line contamination. In addition some oral pathogens could be contaminating and surviving in DUWL.

Science Regarding Dental Unit Water Lines (DUWL): A Review

Water is used as a Coolant and irrigant for various dental procedures. This water that flows through the Dental Unit Water Line (DUWL) should be free of contamination. The microorganisms contaminating the dental unit supplies is different from those which contaminate the drinking water. This article reviews the different provisions to be made in the water pipeline systems to prevent contamination

Italian multicentre study on microbial environmental contamination in dental clinics: a pilot study

The dental practice is associated with a high risk of infections, both for patients and healthcare operators, and the environment may play an important role in the transmission of infectious diseases. A microbiological environmental investigation was carried out in six dental clinics as a pilot study for a larger multicentre study that will be performed by the Italian SItI (Society of Hygiene, Preventive Medicine and Public Health) working group "Hygiene in Dentistry". Microbial contamination of water, air and surfaces was assessed in each clinic during the five working days of the week, before and during treatments. Air and surfaces were also examined at the end of the daily activity. A wide variation was found in microbial environmental contamination, both within the participating clinics and relative to the different sampling times. Microbial water contamination in Dental Unit Water Systems (DUWS) reached values of up to 26 × 10 4 cfu/mL (colony forming units per millilitre). P. aeruginosa was found in 33% of the sampled DUWS and Legionella spp. in 50%. A significant decrease in the Total Viable Count (TVC) was recorded during the activity. Microbial air contamination showed the highest levels during dental treatments and tended to decrease at the end of the working activity (p < 0.05). Microbial buildup on surfaces increased significantly during the working hours. As these findings point out, research on microbial environmental contamination and the related risk factors in dental clinics should be expanded and should also be based on larger collections of data, in order to provide the essential knowledge aimed at targeted preventive interventions.

Free-living Amoebae (FLA): morphological and molecular identification ofAcanthamoebain dental unit water

The aim of our study was to detect free-living Amoebae (FLA) by morphological methods and to identify Acanthamoeba spp. by PCR in the dental unit water lines (DUWL). it was a prospective study dealing with 196 water samples collected from DUWL (94 samples taken in the early morning before materials flush and patient consultations and 102 samples taken after consultations). At the same time, 39 samples from tap water were realized. 135 (69%) samples were positives by the morphological study with morpholypical diversity. The predominant morphotype was the monopodial (39.2%). 18 strains of Acanthamoeba spp. were detected in DUW (13.%) and three strains in tap water (10%). The amplification of 18S rDNA gene of these strains of Acanthamoeba spp. was positive for all samples. the FLA and Acanthamoeba were isolated both in tap water and in dental unit. The amoeba pathogenicity has not been demonstrated after oral or dental contamination; but the presence of intracellular and pathogenic bacteria in the amoeba could be a source of microbiological risks for patients in case of deep dental care or immunodepression. The improvement of this dental unit was necessary by putting a filter of 0.2 microns porosity before the arrival of the water in hand-pieces allowing the limitation of FLA passage.

Isolate-Specific Effects of Patulin, Penicillic Acid and EDTA on Biofilm Formation and Growth of Dental Unit Water Line Biofilm Isolates

Dental unit water line (DUWL) contamination by opportunistic pathogens has its significance in nosocomial infection of patients, health care workers, and life-threatening infections to immunocompromized persons. Recently, the quorum sensing (QS) system of DUWL isolates has been found to affect their biofilm-forming ability, making it an attractive target for antimicrobial therapy. In this study, the effect of two quorum-sensing inhibitory compounds (patulin; PAT, penicillic acid; PA) and EDTA on planktonic growth, AI-2 signalling and in vitro biofilm formation of Pseudomonas aeruginosa, Achromobacter xylosoxidans and Achromobacter sp. was monitored. Vibrio harveyi BB170 bioassay and crystal violet staining methods were used to detect the AI-2 monitoring and biofilm formation in DUWL isolates, respectively. The V. harveyi BB170 bioassay failed to induce bioluminescence in A. xylosoxidans and Achromobacter sp., while P. aeruginosa showed AI-2 like activity suggesting the need of some pretreatments prior to bioassay. All strains were found to form biofilms within 72 h of incubation. The QSIs/EDTA combination have isolate-specific effects on biofilm formation and in some cases it stimulated biofilm formation as often as it was inhibited. However, detailed information about the anti-biofilm effect of these compounds is still lacking.

RETRACTED: Dental unit waterlines: source of contamination and cross-infection

Dental chair units (DCUs) are used in the treatment of many patients throughout each day and microbial contamination of specific component parts is an important potential source of cross-infection. The quality of dental unit water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. This water hosts a diverse microflora of bacteria, yeasts, fungi, viruses, protozoa, unicellular algae and nematodes which may be contaminated with micro-organisms found in the biofilm formed due to water stagnation in the narrow-bore dental unit waterline (DUWL) tubings. The water thus contaminated, when used for various treatment procedures through dental handpieces, air/water/three-in-one syringe, etc., produces aerosols that can cause infection. The present review emphasises the risks of infection from DUWL and various water treatment procedures available to disinfect the DUWLs.

Microbial contamination of dental unit water lines: Evaluation, disinfection and recurrence

Microbial contamination of dental unit water lines: Evaluation, disinfection and recurrence