Part 5: Dental Unit Water Lines

(DU Abstract: In Part 5 of Ozonated Liquids in Dental Practice, the formation of biofilms in water research examining contamination from mains water and ingress of icro-organisms from patients into Dental Unit Water Lines (DUWL’s) is discussed. Published or their ). Biofilms are a nce in aquatic environments, including community drinking water systems. The l-diameter tubing in dental unit waterlines are also sites of biofilm formation. In t the organisms in a slime layer. Part 2: e Chemistry of Ozone G Part 3: Part 4: e Chemistry of Ozone in Wate e Chemistry of Ozone in Plant Part 5: ntal Unit Water Lines (DUWL’s) Part 6: Part 7: al Hygiene & Infection Control riodontal & Implant Care Part 8: sinfection in Dental Practice Part 9: -Home Care & Patient Compliance WL’s). A Review of The Problem & Solutions. pipes is examined. The m research suggests biofilms and their potential for cross-infection present health hazards to the health care worker and other patients during treatment. Detachment of micro-organisms DNA from dental unit biofilm flushed into the oral cavity could theoretically infect the patient. Splatter and aerosols from dental procedures may possibly infect health care personnel (Wirthlin et al 2003). The safety of dental waterlines has been recently questioned on national TV in the USA (PubMed 2000). Szymanska (Szymanska 2005) identified moulds, bacteria and yeasts in biofilms. Some of these in certain circumstances, especially in people with immunological disorders, may be a cause of opportunistic infections (Szymanska 2005). The role of various decontamination agents is discussed. It is suggested that the state-of-the-art is the use of ozone. The integration of the use of ozone into a dental unit extends a system of disinfection and sterilisation for DUWL’s, into the clinical management and patient care arena. Introduction. The quality of dental unit water is of great importance since patients and dental staff are regularly exposed to water from aerosols generated during work, and Dental Unit Water Line (DUWL) contamination has become a concern (Putnins et al 2001, Wirthlin et al 2003 natural occurre interior of smal the lumen of the tubing, the flow is minimal, and progressively decreases to stasis at the interior wall surface of the tubing. Water becomes stagnant when the units are not in use. Molecules precipitate from the water onto the interior wall and promote the adherence of planktonic micro-organisms from the water. Once they become sessile, the micro-organisms change their phenotype. After adherence, there is a socalled surface-associated lag time, and the organisms then enter a growth phase and produce exopolysaccharides that coa Within the biofilm, the micro-organisms can signal one another, transfer nutrients, and exchange genetic material. The insoluble exopolysaccharides shield the micro-organisms from displacement and from penetration by predator organisms, antibiotics, and disinfectants. The external surface layer of micro-organisms is faster growing and may detach as "swarmer" cells. Detachment of micro-organisms from dental unit biofilm flushed into the oral cavity could eoretically infect the patient. es in use were 480 and 1,008 endotoxin units (EU)/ml. This was ignificantly higher than the mean level of 66 EU/ml found in water samples collected from ocedures have an opposite effect to the one desired? waterlines has not been adequately addressed by researchers. acteria have been around for millions of years, and are not without a trick or two of their own over a period of me. This window of opportunity is used by micro-organisms to evolve new species, termed odern health care now faces the problem of bacterial strains which are resistant to a wide infection, and as their hosts tend to live in crowded urroundings, conditions are perfect for micro-organism evolution, cross-infection and survival. Belfast Dental School could be a risk for immuno-compromised adults and cystic fibrosis th Splatter and aerosols from dental procedures may possibly infect health care personnel (Wirthlin et al 2003). DUWL contamination has become a concern to clinical dentistry (Putnins et al 2001).In one study, a viability staining technique identified significantly more bacteria in water than could be cultured (Putnins et al 2001). The mean LPS levels in water collected from highspeed and air & water spray lin s adjacent clinic sinks (Putnins et al 2001). In order to satisfy water regulations and comply with health and safety legislation dentists should institute infection- control measures to maintain the dental unit water at the standard of less than 200 colony-forming units per ml of aerobic bacteria (Pankhurst 2003). However, this may be inadequate with groups of immuno-compromised patients. Manufacturers are instituting water quality standards for dental units at a time when certain fundamental questions remain unanswered (Barbeau & Nadeau 1997): • what should be measured and what methods should be used? • do certain disinfection pr • finally, the question of health risks linked to the colonization of B when survival is threatened. The vast majority of anti-microbial products act ti ‘resistance’, to these disinfection products. M variety of products. In a world where the life expectancy has been lengthened by pharmaceuticals, micro-organisms are now faced with the ultimate choice of host. The micro-organisms’ host is beset with immunological conditions that lower the innate immune system’s ability to contain and repel infection. It is an era of opportunistic s DUWL’s are ideal environments for the growth of micro-organisms entering dental units from the municipal water supply (Barbeau 2000) and from previously treated patients (Montebugnoli et al, 2004). Very few cases of cross-infection have been linked directly to contamination in DUWL’s, but in an era of sociological changes, this risk has grown proportionally (Szymanska 2005). Al Shorman et al (Al Shorman et al 2003) discussed that Pseudomonas aeruginosa found in DUWL’s in children for example. Microbiological Studies of DUWL. Detachment of micro-organisms from DUWL biofilm flushed into the oral cavity could theoretically infect the patient. Splatter and aerosols from dental procedures may possibly infect ealth care personnel (Wirthlin et al 2003). Health care works do not want to isolate themselves om patients by donning full-protective suits. The use of face masks, transparent shields and high day clinical practice in a dental clinical setting despite wareness that this creates anxiety (Domingo et al, 2004) and puts a barrier between the clinical 1.15 +/- 1.04) (P < 0.05). east-like fungi: Candida lbicans, Candida curvata and other yeasts in a Polish study. Some of them, in certain al units at the beginning of the working day, and in 73.3% (22/30) after min of flushing and at midday. Conservative dentistry units had the highest counts, followed by ed to retract saliva from patients under treatment and to release into the mouths of subjects undergoing the next operation. h fr volume suction is now part of every a staff and the patient and carer when present. A Jordanian study (Al-Hiyasat et al 2007) illustrated that stasis in DUWL’s during non-working time results in the proliferation of the biofilm and colony forming units (CFU’s). Overall, the highest counts (log (10) count CFU ml (-1)) were found at the beginning of the working day (1.38 +/- 1.05), and the lowest counts after flushing for 2 min (1.10 +/- 1.03). An increase in the number of CFU’s were seen again at midday ( Various studies have looked at DUWL’s to categorise the microbiological flora involved in the formation of biofilms. Szymanska J (Szymanska 2005) identified moulds: Aspergillus amstelodami, Aspergillus fumigatus, Aspergillus spp. from Aspergillus glaucus group, Aspergillus repens, Citromyces spp., Geotrichum candidum, Penicillium aspergilliforme, Penicillium pusillum, Penicillium turolense, Sclerotium sclerotiorum: y a circumstances and especially in people with immunological disorders, may be a cause of opportunistic infections. In Ireland, Al Shorman et al (Al Shorman et al 2003) and in Jordan Al-Hiyasat et al, (Al-Hiyasat et al, 2007) evaluated the extent of Pseudomonas aeruginosa contamination of DUWL’s at Dental Teaching Centres. Dental units from clinics in conservative dentistry, periodontology, and prosthodontics were examined in the Jordanian study. Al-Hiyasat et al detected P. aeruginosa in 86.7% (26/30) of the dent 2 periodontology and prosthodontics (P < 0.05). Al Shorman et al (Al Shorman et al 2003) showed a reduction in the total volume count (TVC) of water from the control unit from 2.3 x 104 (week 1) and 3.4 x 104 CFU/mL after 2 weeks of installation. The primary coloniser was identified (API 20 NE kit) as pure P aeruginosa. O'Donnell et al (O'Donnell et al 2006) found the most common bacterial species cultured from the mains water were Micrococcus luteus and Sphingomonas spp., respectively, the latter of which are known opportunistic pathogens. Montebugnoli et al in their 2004 paper (Montebugnoli et al 2004) discussed direct person-to-person transmission of periodontal bacteria through saliva. Dental units have been demonstrat it A polymerase chain reaction-based method was used to investigate periodontal pathogenic bacteria inside DUWL’s. The presence of DNA of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Treponema denticola was examined, and positive samples of Prevotella intermedia DNA found. These findings clearly suggest that dental units have the potential to transmit periodontal pathogens between patients. Porteous et al (Porteous et al 2004) found non-tuberculosis mycobacteria in DUWL at a hospital dentistry clinic where immuno-compromised patients are seen. Mycobacterium simiae was isolated from one of the four pre-treatment samples and from two of the four post-treatment samples. Mycobacterium mucogenicum was isolated from one of the four post-treatment samples. io-aerosol formed during dental conservative treatment. The air was collected in the space ted on 25 operative units and had two tages: before application of a DUWL disinfectant and after a 2-week application of disinfection -/+ 90 CFU/ml at the end of dental hand pieces, and 521 -/+ 116 CFU/ml at the end of three-way ontamination of DUWL with Cleaning Fluid Residue and Resin Bonding Issues. t and continuous chemical treatments for DUWL have been developed and marketed. oberts et al (Roberts et al 2000) researched the possible effect of continuous chemical treatment UWL on entin bond strength were examined. The authors used a fifth-generation dentin-bonding agent to chlorite and citric acid regimens. The clinical implications f this 2000 research were that DUWL antimicrobial agents may adversely affect dentin bonding sinfected using a diluted mouthwash solution may be used while bonding resin-based omposite to either enamel or dentin. However dental mouth wash is not a particularly good ned to six treatment groups. One-way ANOVA revealed a significant Microbiological Studies of Turbine and 3-in-1 Spray. A study in 2005 by Szymanska (Szymanska 2005) examined bacterial endotoxin concentration in the water flowing from a high-speed hand piece of a dental unit and in the air contained in the b between the patient and dentist. The study was conduc s procedure. The research showed that the mean concentration of bacterial endotoxin in the water flowing from high-speed hand pieces was significantly reduced after the use of a disinfectant. The mean concentration of bacterial endotoxin in the air was similar at both stages - before and after application of waterline decontamination procedure. The study showed that in dental air-water aerosol, water is the main source of bacterial endotoxin contaminating the aerosol during the work with dental hand pieces. In Japan, Kohno et al (Kohno et al 2004) found that the mean viable bacteria count was 910 1 syringes. C In response to concerns of bacterial biofilm colonization of DUWL, a wide range of commercial intermitten R regimens on dentin-bonding agents. Four proposed antimicrobial agents for use in D d bond composite cylinders to molar dentin surfaces. They then used selected antimicrobial agents as rinsing agents after conditioning. The composite cylinders were shear tested, and their fracture strengths were compared statistically. All proposed antimicrobial agents reduced dentin bond strength. Proposed waterline treatment regimens of a diluted mouth rinse and chlorhexidine significantly reduced dentin bond strength compared with sodium hypo o strength. A 2001 study showed there was no significant difference in shear bond strengths of resin-based composite to tooth structure when rinsed with distilled water mixed with mouthwash, distilled water or water from a municipal source (Knight et al 2001). The clinical implication is that DUWL di c sterilizing medium. Another 2001 study suggested that DUWL biocides may adversely affect adhesion of resin to enamel (Taylor-Hardy et al 2001). This study evaluated the effects of chemical biocides used to control dental unit waterline biofilm on the bond strength of resin to enamel. Sixty bovine teeth were randomly assig difference in means (p < 0.001) and Tukey's multiple range test indicated that three of the tal hard tissues. ds, points to the use of ozone as the DUWL sterilisation method of choice and tate-of-the-art. Con-current studies have shown that ozone does not interfere with dental material cols. The sults from the Holmes J study at 6-months showed that ozone treatment returned alpha scores uce the CFU count zero, the authors concluded that the presence of high heterotrophic bacterial counts, sloughing iodontal wound healing biology. This can be idened to include any form of dental surgery from tooth removal, to implant placement. Most for reducing UWL contamination were investigated using newly installed dental units. Over a 2-month dent water reservoirs, a sodium hypochlorite disinfection gimen, daily draining and purging of DUWL’s and point-of-use filters by assessing microbial experimental groups had significantly lower mean shear bond strengths than the control (p < 0.05). A 2004 study examined the effects of biocide contamination of DUWL (von Fraunhofer et al 2004). In their closing discussion, they comment on the varying reports on the effects of such agents on the bond strength of restorative dental materials and, particularly, between these agents and den Failure of the enamel-resin bond can lead to marginal micro-leakage around the periphery of the restoration. Failure of this margins results in staining – the ingress of diet-related chromogenic organic molecules, establishment of the acid-niche environment, and eventual failure of the restorative care. The outstanding results of the Al Shorman et al (Al Shorman et al 2003) paper, where the bacterial count of samples collected showed a bacterial reduction from 5.2*103 CFU/ml before treatment to 300 CFU/ml after the first O3 application and then to 0 CFU/ml after the second application onwar s bond strengths or material retention (Campbell et al 2003 and Abu-Naba'a et al 2004). The findings from the Campbell et al (Campbell et al 2003) study were illustrated in the Holmes study (Holmes 2004) where these bonding issues were further examined. After ozone treatment, resin bonding was carried out over soft, previously-infected dentine. This flies in the face to all conventional teaching with regards to cavity preparation and dentine bonding proto re on the UHPS criteria for all restorations placed in this way. It is argued that the incorporation of ozone into a dental unit will have a major impact on the standard of care delivered by a dentist with either limited investment in instrumentation, or those of mediocre skills. Implications in Dental Surgery Wound Healing. In the Putnins et al (Putnins et al 2001) paper in 2001, the role of the infective biofilm in DUWL’s was discussed with relation to surgery. As it was not possible to red to biofilm, and high LPS levels posed a real risk to per w dental practices in the western world use sterile saline, but it other areas of the world this is not available for routine use. The incorporation of ozone would of course revolutionise not only the pre- and post- surgical aspects, but the surgical process itself. Ozone is known to encourage wound healing as well as control and prevent opportunistic infection (Bocci 1994). Solutions to the Infective Biofilm. In a study from the United States of America in 1997 (Murdoch-Kinch et al 1997) the effectiveness of American Dental Association (ADA) recommended approaches D period, the authors studied indepen re contamination and biofilm development using scanning electron microscopy. The findings demonstrate that DUWL contamination can be controlled when dental personnel use available technologies and adhere to recommended maintenance protocols. However, employee compliance with instructions is an issue, in the same way the dental profession whinge about patient compliance to oral hygiene instructions and dietary advice. In Jordan, Al-Hiyasat et al, (Al-Hiyasat et al 2007) found that flushing the dental unit for 2 minutes significantly reduced the counts of P. aeruginosa, but flushing with infected water is not going to eliminate the biofilm, nor will it reduce the CFU count to zero. Another study from the USA in 2002 (Cobb et al 2002) concluded that after four minutes of ria at each time interval ompared to the baseline and between each successive time interval. However, the level of CFU’s not a strong irritant. These authors concluded that ontrolling DUWL biofilm would have beneficial effects on nosocomial infections. e S. mutans markably decreased. These researchers noted that ozonated water strongly inhibited the icantly decreased. These researchers concluded that used ith ultrasonic instrumentation, ozonated water application may be useful for endodontic therapy. ith minimal effort by dental staff (Montebugnoli et al 2004). Porteous et al urged dental ‘Microbiological Studies continuous flushing (the current ADA recommendation), all waterlines still harboured CFU levels that exceed current ADA recommendations. Cobb CM et al concluded that water flushing of DUWL’s produced a statistically significant reduction in planktonic bacte c after four minutes of continuous water flushing still exceeded the current ADA recommendations for acceptable levels of micro-organisms. Wirthlin et al (Wirthlin et al 2003) in their 2003 paper showed that chlorine dioxide waterline cleaners are effective in decontaminating DUWL biofilms. Chlorine dioxide has advantages over other chlorine products: it does not form carcinogenic compounds, has a long shelf-life in comparison with other products, and is c A study published by Nagayoshi, Fukuizumi et al (Nagayoshi, Fukuizumi et al 2004) examined the effect of ozonated water on oral micro-organisms and dental plaque. Almost no microorganisms were detected after being treated with ozonated water (4 mg/l) for 10 s. When the experimental dental plaque was exposed to ozonated water, the number of viabl re accumulation of experimental dental plaque in vitro. After the dental plaque samples from human subjects were exposed to ozonated water in vitro, almost no viable bacterial cells were detected. These results suggest that ozonated water should be useful in reducing the infections caused by oral micro-organisms in dental plaque. A further study by Nagayoshi, Kitamura et al (Nagayoshi, Kitamura, et al 2004) examined the effect of ozonated water against Enterococcus faecalis and Streptococcus mutans infections in vitro in bovine dentin. After irrigation with ozonated water, the viability of E. faecalis and S. mutans invading dentinal tubules signif w Kohno et al in 2004 (Kohno et al 2004) published their results that indicated acidic electrolyzed water could be applied as an appropriate measure against bacterial contamination of the DUWL. Montebugnoli L et al concluded in their 2004 paper that dental manufacturers should be invited to design dental units that incorporate automated devices to disinfect DUWL’s between patients w practitioners in 2004 (Porteous et al 2004) to understand the limitations of available DUWL treatments, and to consider the use of sterile water for non-surgical, as well as surgical, treatment of immuno-compromised patients to reduce the risk of cross infection. In 2005, Szymanska (Szymanska 2005) concluded that the application of a disinfection product containing hydrogen peroxide caused a significant decrease both in the number of total fungi and individual fungal species. This confirmed his assertion that hydrogen peroxide was effective for fungal decontamination of DUWL’s. In another paper from 2005 titled of Turbine Spray’, Szymanska commented that the application of a user-friendly water ushroomed until the inter-war periods, when the advent of cheap chlorine aw the use of O3 decline. The pharmaceutical industry began to flood the market with the wide st is beset with immunological conditions that lower e innate immune system’s ability to contain and repel infection. And there is a trend to zone leaves no biocidal traces so the risk of contamination in bonding procedures is removed. liminate the DUWL biofilm. Not surprising, CFU values after O3 treatment f excess 10,000 CFU were reported. ype spores were not mutagenised by ozone and wild-type nd recA spores exhibited very similar ozone sensitivity. Spores (termed alpha-beta-) lacking the disinfectant to significantly decrease endotoxin concentration in the aerosol is one of recommended methods to reduce health risk. O'Donnell et al (O'Donnell et al 2006) discussed a Water Management System, described as ‘an integrated and automated DUW cleaning system’. This was investigated over a 12-month period. The system uses hydrogen peroxide- and silver ion-containing disinfectants in a once-weekly disinfection protocol. Ozone has been used for purification of water due to its efficiency and lack of side effects. It has been used in the medical profession since the late 19th Century to treat infections and aid wound healing. In the 1920’s Dr Edwin Parr, a Swiss dentist started, to use O3 as part of his disinfection system. The use of O3 m s variety of anti-microbials we know today. The vast majority of anti-microbial products act to kill micro-organisms over a period of time. This window of opportunity is used by bacteria to evolve resistance to these disinfection products, and modern health care now faces the problem of bacterial strains which are multipleproduct resistant. The micro-organisms’ ho th increased life span that requires pharmaceutical products for continued survival. The risk of cross-infection into this group of the population cannot be over looked. Looked at in terms of ‘What is the perfect anti-microbial agent?’, ozone would seem to fit the required profile. Ozone acts instantly, by oxidising bacteria, fungi, viruses, prions, and their effluent bio-molecules. Micro-organisms cannot evolve fast enough to develop resistance to O3, so it remains the ‘perfect’ disinfection and sterilisation product to use. However, O3 is not without its own issues. From a physical property perspective, O3 is a very unstable gas, and has to be manufactured at the point of use. The equipment to deliver O3 has an associated cost. But it is a one-time investment that is still more economical than disinfectant use. O The potential health risk with free O3 in the oral cavity and the work place must be addressed, and this would be carried out as part of the risk assessment and design of the ozone system integrated into the dental unit. In an early paper from 2002 Cardon et al (Cardon et al 2002) concluded that an ozonation system evaluated appeared to have no long-term benefit on DUWL biofilm control. However on closer reading, the concentration of O3 used, 0.01 to 0.06 ppm, would not have been sufficient to lower high CFU levels or e o In 2004, Young and Setlow (Young and Setlow 2004) determined that ozone does not kill spores by DNA damage. Rather, ozone seems to render the spores defective in germination, perhaps because of damage to the spore's inner membrane. They reported that ozone does not cause damage to the spore's DNA, as wild-t a two major DNA protective alpha/beta-type small, acid-soluble spore proteins exhibited decreased ozone resistance but were also not mutagenised by ozone, and alpha-beta- and alpha-beta-recA spores exhibited identical ozone sensitivity. Killing of spores by ozone was greatly increased if spores were chemically decoated or carried a mutation in a gene encoding a protein essential for assembly of the spore coat. Young and Setlow also reported that ozone-killed spores did not germinate with either nutrients or Ca(2+)-DPA and could not be recovered by lysozyme treatment. These workers concluded the major factor in spore resistance to sterilisation agents appears to be the spore coat. Spore killing by ozone seems to render the spores defective in germination, perhaps because of damage to the spore's inner membrane. This study underlines that concerns that ozone may cause mutations in cells may be unfounded, despite the production of radicals in water and fluids. Al Shorman et al (Al Shorman et al 2002) used O3 at a concentration of 2100 ppm bubbled into 1 tre of water over a 10-minute time period. O3 formed from dry air resulted in a bacterial s. The authors commented on how low the oncentration could be lowered and retain efficacy. Puttaiah and Lin (Puttaiah and Lin 2006) in x 104 and 3.4 x 104 CFU/mL after 1 and 2 weeks of installation. After the first O3 eatment the TVC was reduced to 60 CFU/mL and rose to 3.9 x 104 CFU/mL after a week with d to determine the nature and extent of the oxidation of biomolecules present in carious dentine, plaque and saliva. Experimental samples were treated with ozonated (2 orresponding primary oxidation products, cystine and methionine sulphoxide respectively li reduction from 5.2*103 CFU/ml before treatment to 300 CFU/ml after the first O3 application and then to 0 CFU/ml after the second application onward c an IADR abstract published in 2006 used 0.8 ppm of ozonated water as irrigant. At the end of week four all Units showed counts > 500 cfu/mL. They concluded that an initial cleaning with 60 ppm ClO2 and use of 0.8 ppm O3 mixed in water as irrigant controlled contamination up to 30 days. In a follow-up study in 2003, Al Shorman et al (Al Shorman et al 2003) compared hydrogen peroxide and O3 DUWL decontamination. Hydrogen peroxide continuously produced water with a Total Viability Count (TVC) of less than 100 CFU/mL. The TVC of water from the control unit was 2.3 tr few Pseudomonas colonies. After two weeks, TVC was 2.8 x 103CFU/mL CFU/mL and became 0 CFU/mL after the treatment. Repeated sampling of the unit for 9 weeks showed 0 CFU/mL. Flushing with water could not maintain a CFU or TVC value within acceptable potable water standards (200 CFU). In 2007, Shenberg et al (Shenberg et al 2007) showed ozone is extremely reactive towards selected carious dentine biomolecules, and such reactions are likely to be of relevance to its reported microbiocidal activity. High resolution proton (1H) nuclear magnetic resonance (NMR) spectroscopy was use ppm) water These results mirrored previous studies (Holmes 2003 and Holmes 2003) where ozonated water showed marked reductions in volatile sulphur compounds. In these earlier studies, the Halimeter, a volatile sulphur detection system, was used. In the Shenberg 1H NMR study, ozone was shown to attack: • a-D-glucose, giving rise to formate as it’s by-product • pyruvate with acetate and CO2 via an oxidative decarboxylation process • amino acid volatile sulphur compound precursors cysteine and methionine were oxidatively transformed to their c These results are similar to the published 1H NMR studies from previous years where carious e samples were treated with ozone. The Shenberg study shows that ozone dissolved in water the ability to denature bio tissu has -molecules seen in active decay and also found in oral saliva. ces to disinfect DUWL’s between patients with minimal effort by dental staff (Montebugnoli et al lly significant reduction in planktonic bacteria at each time interval compared to the aseline and between each successive time interval (Cobb et al 2002). However, the level of roved by the appropriate gencies, they will offer even more preventive choices. It is fortunate that there are multiple nts (Putnins et al 2001, Porteous et al 2004). re. Ozonated water exceeds all urrent standards for water quality in DUWL’s at high enough concentrations. 003: Holmes and ynch, 2003) have shown conclusively that the use of O3 in dental care is effective as a nonthod to manage decay and its destructive effects. The use of O3 has been shown to e the ideal way to manage anxiety of patients – young and old - and their carers (Dahnhardt et 003) and raises the practice income. In Endodontics, O3 is ffective against Enterococcus faecalis (Chang et al, 2003, Nagayoshi, Fukuizumi et al, 2004) employment for medical, dental & veterinary purposes. This statement has been echoed by Summary of this Paper Review. 1. Manufacturers should be invited to design dental units that incorporate automated devi 2004). 2. After four minutes of continuous flushing, all waterlines still harboured CFU levels that exceed current ADA recommendations. It is concluded that water flushing of DUWL’s produced a statistica b CFU’s after four minutes of continuous water flushing still exceeds the current ADA and European recommendations for acceptable levels of micro-organisms. 3. Choices are available for preventing and controlling waterline contamination, but some of them require a substantial commitment by personnel charged with maintenance of the waterlines. Other approaches and technologies should be developed and tested. If app a options available, but currently each protocol requires a serious commitment for follow-through (Molinari 1999). 4. Dental practitioners need to understand the limitations of available DUWL treatments, and to consider the use of sterile water for non-surgical, as well as surgical, treatment of immunocompromised patie 5. The use of ozone as the method of disinfection would offer the best solution as part of an integrated approach to dental care. Indeed, O3 would seem to offer the opportunity of unit sterilisation which is a very different approach to dental unit ca c Conclusion. Studies from Europe (Abu-Salem et al 2003: Baysan and Lynch 2001: Holmes 2 L destructive me b al, 2003: Domingo et al, 2004). The effects of O3 reduce tooth destruction in routine preparation (Clifford, 2004: Holmes, 2004: Holmes and Lynch, 2004) and O3 reduces the time and the cost of dental care (Domingo and Holmes, 2004: Johnson et al, 2 e which is implicated in endodontic treatment failure. O3 does not interfere with dental material bond strengths, and there is evidence that it increases material retention (Abu-Naba'a et al 2004, Campbell et al 2003). Bocci (Bocci 1994) has emphasised that the potential toxicity of O3 should not preclude its thousands of health professionals who use ozone in clinical practices around the world, and millions of patients that have been treated. The results of these studies show that ozone reduces e necessity for filling materials of unknown long-term potential toxicity. s. relationship with acteria. Should mankind be surprised that we also have mutated in other areas at a cellular level? oung and Setlow’s published research reported that ozone does not cause damage to the spore's proteins exhibited decreased ozone resistance ut were also not mutagenised by ozone, and alpha-beta- and alpha-beta-recA spores exhibited to render the spores defective in germination, perhaps because of damage to the pore's inner membrane. the potential for cross infection. al action of aqueous solution of O3 in entistry. stergard (Vestergard 1994) who was looking at establishing and maintaining pathogen ee conditions in aqueous solutions using ozone. Vestergard’s paper examined the use of ozone in space applications for the elimination of pathogens using ozone. Vestergard’s area of research th The use of ozone as the method of disinfection would offer the best solution as part of an integrated approach to dental care. Indeed, O3 would seem to offer the opportunity of unit sterilisation which is a very different approach to dental unit care. Ozonated water exceeds all current standards for water quality in DUWL’s at high enough concentration As part of a dental treatment unit, ozone can easily be integrated into routine dental care. Some detractors have tried to suggest that the regular usage of ozone could cause mutations in human cells. But what if mankind as we understand him/her now is that mutation? The energy houses of the human cell, mitochondria, are known remnants from a past symbiotic b In 2004, Young and Setlow (Young & Setlow 2004) determined that ozone does not kill spores by DNA damage. Rather, ozone seems to render the spores defective in germination, perhaps because of damage to the spore's inner membrane. Y DNA, as wild-type spores were not mutagenised by ozone and wild-type and recA spores exhibited very similar ozone sensitivity. Spores (termed alpha-beta-) lacking the two major DNA protective alpha/beta-type small, acid-soluble spore b identical ozone sensitivity. Killing of spores by ozone was greatly increased if spores were chemically decoated or carried a mutation in a gene encoding a protein essential for assembly of the spore coat. Young and Setlow also reported that ozone-killed spores did not germinate with either nutrients or Ca(2+)-DPA and could not be recovered by lysozyme treatment. These workers concluded the major factor in spore resistance to sterilisation agents appears to be the spore coat. Spore killing by ozone seems s The Young and Setlow study would seem to suggest concerns that ozone may cause mutations in cellular DNA may be unfounded, despite the production by ozone of radicals in water and fluids. This study also demonstrates the important role ozone plays in the sterilisation of water, fluid lines and the reduction of The referenced research for the dental use of ozonated fluids date back to the 1950’s. Wuhrmann and Meyrath examined the bactericidal effect of aqueous ozone solutions (Wuhrmann and Meyrath 1955), effectively repeating the observations of Dr Edwin Fisch in 1932. In the 1960’s. Onouchi in 1965 (Onouchi 1965) examined the bactericid d The research into ozonated fluids have examined the effects of drinking ozonated water on gut infections (vanden Bossche et al 1994), and Khadre and Yousef (Khadre and Yousef 2001) examined the sporicidal action of ozone and hydrogen peroxide. This study built on the earlier work of Ve fr was creating pathogen free conditions in aqueous solutions containing organic matter. This research, although concerned with hydroponic agricultural systems, can be carried into general potable water studies and water distribution networks, including DUWL’s. Studies to look at increasing the solubility of ozone in fluids have identified that the use of ultrasonics (Zhang et al 2007) increases ozone solubility, and allows the use of less powerful ozone generators. Dental researchers have started to examine the effects of ozonated fluids in periodontal disease. uth et al in two papers in 2006 and 2007 (Huth et al 2006, Huth et al 2007) examined the effect bial effect. incubation with ozonized medium. The Huth 2007 study stablishes a condition under which aqueous ozone exerts inhibitory effects on the NF-kappaB the use of ozonated water inactivates ntibacterial agents (Dodd et al 2006) and in particular amoxicillin (Andreozzi et al 2005), tract 2003, 2004 bu-Salem OT, Marashdeh MM, Lynch E. Ozone Efficacy in Treatment of Occlusal Caries in . IADR Abstract 2003 nt J Dent Hyg. 2007 Feb:5(1):36-44. H of ozone on periodontal tissues. The 2007 paper compared traditional periodontal anti-microbial products with the use of ozonated water. Both papers concluded that ozonated water has an excellent anti-micro Huth et al (Huth et al 2007) in their later paper examined the effect of ozone on the influence on the host immune response. These researchers chose the NF-kappaB system, a paradigm for inflammation-associated signaling/transcription. Their results showed that that NF-kappaB activity in oral cells in periodontal ligament tissue from root surfaces of periodontally damaged teeth, was inhibited following e system, suggesting that it has an anti-inflammatory capacity (Huth et al 2007). The use of ozonated water in dental ultrasonic systems, such as scalers, sonic preparation systems (KaVo Sonic-Sys, KaVo GmbH, Germany) and air abraision systems would seem to be supported by Zhang et al 2007, Huth et al 2006 and Huth et al 2007. There are many benefits to drinking ozonated water, to control oral hygiene and as a source of sterile water. However, patients should also be informed that there is an interaction of aqueous ozone with anti-microbials. This research has been published, illustrating the importance of potential interactions of dissolved ozone and prescribed anti-microbials. Patients who are taking a course of antibiotics may need to be informed that a progesterone (Barron et al 2006) and tetracycline (Dalmázio et al 2007). For concern to dentists is that ozone may inactivate the anti-microbial effects of triclosan (Suarez et al 2007). A current topic of debate in dental material science and long term potential effects, are endocrine disruptors found in resin-based dental restorative materials. Deborde et al (Deborde et al 2005) showed endocrine disruptors were destroyed by ozonated water. 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