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Biomedical subjects

W R Moorer

Publications and source records attributed to W R Moorer.

At least 19 recordsLinked to original sources
PubMed2006

Attitudes of general dental practitioners in Europe to the microbial risk associated with dental unit water systems.

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

Attitude of Health Personnel↗
PubMed2006

Comparison of the efficacies of disinfectants to control microbial contamination in dental unit water systems in general dental practices across the European Union.

Water delivered by dental unit water systems (DUWS) in general dental practices can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWS provide a reservoir for microorganisms and should be controlled. This study compared disinfection products for their ability to meet the American Dental Association's guideline of <200 CFU x ml(-1) for DUWS water. Alpron, BioBlue, Dentosept, Oxygenal, Sanosil, Sterilex Ultra, and Ster4Spray were tested in DUWS (n = 134) in Denmark, Germany, Greece, Ireland, The Netherlands, Spain, and the United Kingdom. Weekly water samples were tested for total viable counts (TVCs) on yeast extract agar, and, where possible, the effects of products on established biofilm (TVCs) were measured. A 4- to 5-week baseline measurement period was followed by 6 to 8 weeks of disinfection (intermittent or continuous product application). DUWS water TVCs before disinfection ranged from 0 to 5.41 log CFU x ml(-1). Disinfectants achieved reductions in the median water TVC ranging from 0.69 (Ster4Spray) to 3.11 (Dentosept) log CFU x ml(-1), although occasional high values (up to 4.88 log CFU x ml(-1)) occurred with all products. Before treatment, 64% of all baseline samples exceeded American Dental Association guidelines, compared to only 17% following commencement of treatment; where tested, biofilm TVCs were reduced to below detectable levels. The antimicrobial efficacies of products varied (e.g., 91% of water samples from DUWS treated with Dentosept or Oxygenal met American Dental Association guidelines, compared to 60% of those treated with Ster4Spray). Overall, the continuously applied products performed better than those applied intermittently. The most effective products were Dentosept and Oxygenal, although Dentosept gave the most consistent and sustained antimicrobial effect over time.

Biofilms↗
PubMed2004

Microbiological evaluation of dental unit water systems in general dental practice in Europe.

A range of opportunistic pathogens have been associated with dental unit water systems (DUWS), particularly in the biofilms that can line the tubing. This study therefore aimed to assess the microbiology of DUWS and biofilms in general dental practices across seven European countries, including the United Kingdom (UK), Ireland (IRL), Greece (GR), Spain (ES), Germany (D), Denmark (DK) and the Netherlands (NL). Water supplied by 51% of 237 dental unit water lines exceeded current American Dental Association recommendations of < or = 200 colony-forming units (CFU) ml(-1). Microbiological loading of the source waters was between 0 (Denmark, the Netherlands and Spain) and 4.67 (IRL) log CFU ml(-1); water line samples from the DUWS ranged from 1.52 (ES) to 2.79 (GR) log CFU ml(-1); and biofilm counts ranged from 1.49 (GR) to 3.22 (DK) log CFU.cm(-2). Opportunistic pathogens such as legionellae (DK and ES), including Legionella pneumophila SG1 (DK and GR), and Mycobacterium spp. (DK, NL, GR, D and ES) were recovered occasionally. Presumptive oral streptococci (ES and NL), oral anaerobes (GR), Candida spp. (UK, NL and ES) and blood (GR and IRL) were detected at relatively low frequencies, but their presence indicated a failure of the 3-in-1 antiretraction valve, leading to back siphonage of oral fluids into the water and biofilm phase. These findings confirm that a substantial proportion of DUWS have high levels of microbial contamination, irrespective of country, type of equipment and source water. The study emphasizes the need for effective mechanisms to reduce the microbial burden within DUWS, and highlights the risk of occupational exposure and cross-infection in general dental practice.

Bacteria↗
PubMed2004

[Solvents for the removal of gutta-percha from root canals. 1. Efficacy].

The removal of gutta-percha and sealer from endodontically treated root canals may prompt the use of organic solvents. In the present article a number of possible solvents are described and, based upon the literature, their efficacy is assessed. Some solvents, amongst which chloroform, xylene and halothane are almost equally efficient, although all leave a debris of gutta-percha and sealer in the root canals behind. Only chloroform solves AH26 and most probably AH-plus, but very slowly. Eucalyptol and turpentine oil are slow dissolvers. Orange oil and limonene are promising. The data on other solvents, if candidates at all, are scarce. The choice of a solvent is co-determined by factors such as toxicity and sensitisation, which will be described in a second publication.

Gutta-Percha↗
PubMed2004

[Solvents for the removal of gutta-percha from root canals. 2. Side effects of chloroform, halothane and xylene].

High concentrations of organic solvents have adverse effects on the health of professional workers. In endodontics, halothane, chloroform and xylene are used to dissolve gutta-percha from root canals. It is therefore questioned whether the use of these solvents could affect the health of patients or of the dental team. It seems warranted to conclude that the amounts and concentrations of chloroform, xylene and halothane such as used in endodontic retreatment, are low and therefore are safe. However, the dentist should be aware of possible hypersensitivity induced by previous application of halothane as a narcotic.

Chloroform↗
PubMed2003

Antiviral activity of alcohol for surface disinfection.

Bacteria and viruses from the patient's mouth travel with dental splatter and spills. A surface disinfectant should possess antiviral activity as well as antibacterial action. Because of frequent and 'open' application in the dental office, such a disinfectant should be non-toxic, non-allergenic and safe for the hygienist. It now appears that high-concentration alcohol mixtures (i.e. 80% ethanol + 5% isopropanol) are not only excellent antibacterials, but quickly inactivate HIV as well as hepatitis B and hepatitis C viruses. Compared to alternative surface disinfectants, use of high-concentration alcohol for the spray-wipe-spray method of surface disinfection in dentistry appears safe and efficient. However, dried matter should be wiped and hydrated first.

Anti-Bacterial Agents↗
PubMed2003

[110th year Nederlands Tijdschrift voor Tandheelkunde. 2. Root canal treatment, intra-canal disinfectants and bacterial culture: past and present].

Fifty years ago the Dutch Journal of Dentistry published methods and opinions concerning root canal treatment. Qualitative bacterial culture, inclusion of aggressive disinfectants, as well as antibiotics and widening of the apical constriction were carried out. Nowadays, because of several reasons, these are not clinical practice anymore. Controversy over the clinical consequences of bacterial presence in tubules and in the peri-apical area prevailed in the past and seem to be prevalent once again.

Dental Disinfectants↗
PubMed2003

[Prevention of viral cross-infection. Surface disinfection with 80% ethanol].

High concentrations (80-90%) of ethanol seem to be best for use in the dental office. A mixture of 80% ethanol and 5% isopropanol was shown to inactivate HIV, hepatitis B and C viruses within 20 seconds. Compared with alternative antiviral disinfectants, such a mixture is non allergenic and minimally toxic for the dental team. It is suitable for spraying or for the spray-wipe-spray technique as an important cross-infection control measure in dentistry.

Cross Infection↗
PubMed2002

The virucidal spectrum of a high concentration alcohol mixture.

The virucidal spectrum of a high concentration alcohol mixture (80% ethanol and 5% isopropanol) was determined for a broad series of lipid-enveloped (LE) and non-lipid-enveloped (NLE) viruses covering all relevant blood-borne viruses. LE viruses were represented by human immunodeficiency virus (HIV), bovine viral diarrhoea virus (BVDV), a specific model virus for hepatitis C virus (HCV), pseudorabies virus (PRV), and vaccinia virus. For the NLE viruses hepatitis A virus, canine parvovirus (a model for human parvovirus B19), and reovirus type 3 (Reo-3) were used. PRV, vaccinia, and Reo-3 served as general model viruses. The alcohol mixture was spiked with 5% (v/v) virus, mixed and tested for residual virus after 5 min treatment. Complete clearance (reduction by a factor of >10(6)) was observed for LE viruses, whereas incomplete to insignificant clearance (ranging from no reduction up to a maximum factor of 10(4)) was found for NLE viruses. In a second series of spiking experiments using the LE viruses BVDV, HIV, and PRV, complete clearance (reduction by a factor of >10(6)) was found after 20 s treatment. These data strongly suggest that treatment with a high concentration alcohol mixture has a high virucidal potential in particular for the blood-borne LE-viruses HIV, hepatitis B virus, and HCV. Such mixtures are well suited for rapid and frequent disinfection in dental practice being non-hazardous and non-toxic.

2-Propanol↗
PubMed2000

Penetration of bacteria in bovine root dentine in vitro.

AIM: The aim of this study was to develop a test model to quantify the penetration of bacteria into dentinal tubules. METHODOLOGY: The model consisted of two compartments separated by a bovine dentine specimen with a thickness of 1.5-3.1 mm. The root cementum was removed from the root surface and the specimens were oriented in the model with the pulpal side facing the inoculated chamber of the test model. One compartment contained the test organism and the other was filled with sterile broth that was evaluated for growth of the test organism. The depth of bacterial penetration was measured in the dentine with or without a smear layer using both a histological and a quantitative recovering grinding technique, after 6 weeks of exposure to the microorganisms. RESULTS: E. faecalis penetrated dentine significantly deeper than A. israelii (P < 0.001). After removal of the smear layer with EDTA, E. faecalis penetrated significantly deeper than in dentine pretreated with saline only (P < 0.01) or with a combination of saline and sodium hypochlorite (P < 0.01). Microorganisms were found in 89% of the cultured specimens and in 80% of the specimens that were evaluated with light microscopy. Total penetration through the dentine specimen and infection of the broth in the test compartment of the model occurred in only two out of 72 specimens. CONCLUSION: Collection and immediate culturing of infected dentine dust and counting colony forming units (CFU) allowed an overview of the number of bacteria per sample and was more sensitive than microscopy. Removal of the smear layer enhanced bacterial penetration.

Actinomyces↗
PubMed2000

[Hormone dysregulators. Pseudo-estrogens in dental composite resins and sealanta?].

A number of polluting chemicals in the ecosystems must be characterized as hormone disruptors. Among others, male animals appear to become feminized by the action of the so-called pseudo-estrogens and under their influence mens' fertility is said to decrease. Composites and sealants based on Bis-GMA resin may contain bisphenol-A as an impurity and Bis-DMA, from which in saliva bisphenol-A will be formed by hydrolytic degradation. Therefore, in extreme circumstances a weak estrogenic effect is not impossible on the short-term. However, the amounts of these probably not very potent estrogenic compounds are small, thereby resulting in a tolerable risk on the short term. Long-term-effects and synergism with pseudo-estrogens from other sources prompt further studies in order to verify the safety of the Bis-GMA containing products.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1995

The fate and the role of bacteria left in root dentinal tubules.

In this article the question of the relevance and consequences of bacteria remaining in the tubules of root dentine after cleaning and shaping of the root canal space is addressed. A second aim is to discuss the necessity of clinical measures taken to eradicate those bacteria that are presumed to survive there. The available clinical and experimental evidence supports the use of antibacterial dressings in cases where the root canal space remains temporarily unobturated after removal of necrotic and infected pulp tissue. There is no evidence, however, that special measures should be taken to kill the bacteria in the dentinal tubules. Should time permit, a sound obturation technique immediately following the cleaning, shaping and disinfection phases allows the remaining bacteria in the tubules to be either inactivated or prevented from repopulating the (former) canal space. In the vast majority of cases, those bacteria appear not to jeopardize the successful outcome of root canal treatment.

Dentin↗
PubMed1994

[HIV and dentistry. Part 5. Practice hygiene].

When complying a good standard hygiene protocol in the dental office the risk of cross-infection of whatever type of microorganism, including the hepatitis-B-virus and HIV, is almost eliminated.

Cross Infection↗
PubMed1993

Fluid transport and bacterial penetration along root canal fillings.

Convective transport of water from the coronal to the apical end of obturated root canals was determined by the movement of an air bubble in a capillary glass tube connected to the apex of the experimental root section using a headspace pressure of 120 kPa (1.2 atm). Water transport through existing voids in the obturated canals could be measured reproducibly in this way. The root canals of 60 human maxillary canines were filled with gutta-percha and sealer by the cold lateral condensation technique. Thirty of these were first exposed to a small motile bacterium, Pseudomonas aeruginosa, growing in a reservoir at the coronal end of each root. After 50 days, two specimens allowed penetration of bacteria to a reservoir at the apical end. All the roots were then assessed quantitatively for convective transport of water. The results were divided into three defined categories: 39 obturated canals were in the 'bacteria tight' category, 14 canals in the 'slight leakage' and 7 canals in the 'gross leakage' category. The two specimens that showed bacterial penetration fell into the slight and gross leakage categories. The previous test for bacterial passage did not statistically influence the fluid transport pattern of these roots which was measured subsequently. These findings indicate that fluids transport through obturated root canals, most of which do not allow the passage of bacteria.

Biological Transport↗
PubMed1993

Calcification of a cariogenic Streptococcus and of Corynebacterium (Bacterionema) matruchotii.

The main aim of this investigation was to challenge the idea that cariogenic streptococci do not calcify. Calcium uptake of calcification of Streptococcus mutans C180-2, proven to be an acidogenic and cariogenic strain, was compared with calcium uptake and calcification of Corynebacterium (Bacterionema) matruchotii, known as a ready calcifier. Bacteria were grown on Brain Heart Infusion Agar (BHIA) and on well-buffered semi-synthetic E-agar, both containing 1.4 mmol/L calcium, 2 g/L glucose, initial pH 7.4. Calcium uptake from BHIA by C. matruchotii (25 mmol Ca/kg wet bacterial cell mass), but not by S. mutans, was found. Grown as a plaque-like lawn on E-agar, the S. mutans cell mass concentrated calcium to 63 +/- 11 mmol/kg compared with 145 +/- 61 mmol/kg in C. matruchotii. X-ray diffraction confirmed the presence of crystalline apatite in the bacterial cell masses. Electron microscopy revealed crystals and mineralized deposits in both organisms. Heavy calcifications in some cells of S. mutans were seen. Calcification was partly inhibited by magnesium ion and by methanehydroxybisphosphonate. S. sobrinus 6715, as well as freshly isolated S. mutans and S. sobrinus from patients, concentrated very large quantities of calcium, up to 500-fold from the medium, when maintained for several weeks on E-agar of initial pH 7.6. Our observations widen the view on acidogenic bacteria as mineralization agents and support the notion that members of the mutans group of streptococci may be involved in events that trigger heavy intracellular calcifications and, possibly, dental calculus formation.

Agar↗