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.

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.

Thiocyanate as a cofactor in myeloperoxidase activity against Streptococcus mutans.

Inhibition of glycolysis of some oral bacteria was established in vitro by an antibacterial system, consisting of myeloperoxidase, H2O2, and a cofactor. When thiocyanate was used in physiological concentration as a cofactor, the system acted (at low pH) bactericidally on Streptococcus mutans, as indicated by the determination of viable counts. However, at neutral pH, the glycolysis of Streptococcus mutans was inhibited, while its viability remained unaffected. The possible role of such a pH-dependent antibacterial system in the oral cavity is discussed.

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.

[Prevention of viral cross-infection. Surface disinfection with 80% ethanol]. / Preventie van virale kruisinfectie. Oppervlaktedesinfectie met 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.

[Pain, flare-ups and failures in root canal therapy]. / Pijn, opvalmming en mislukking na de wortelkanaalbehandeling.

In this overview the incidences and causes of pain, flare-ups and failures that occur after root canal therapy are discussed. Infection is considered the most important single, underlying determinant of the many factors that may cause pain and failures. Therefore, strict adherence to recognized therapeutic principles of shaping, disinfection and filling, in addition to proper aftercare, is of importance to diminish postoperative sequelae.

[Recommended protection against infection in the dental office]. / Verantwoorde bescherming tegen infecties.

Identification of pathways of microbial contamination and assessment of corresponding infection risks in general dental practice, precede the recommendation of infection control activities. Ten practical and appropriate rules are suggested.

[Hormone dysregulators. Pseudo-estrogens in dental composite resins and sealanta?]. / Hormoonontregelaars. Pseudo-oestrogenen in tandheelkundige composieten en sealants?

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.

[110th year Nederlands Tijdschrift voor Tandheelkunde. 2. Root canal treatment, intra-canal disinfectants and bacterial culture: past and present]. / 110e jaargang NTvT 2. De wortelkanaalbehandeling met medicamenten en de bacteriekweek: toen en nu.

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.

[Solvents for the removal of gutta-percha from root canals. 2. Side effects of chloroform, halothane and xylene]. / Oplosmiddelen ter verwijdering van guttapercha uit wortelkanalen 2. Nevenwerkingen van chloroform, halothaan en xyleen.

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.

[Solvents for the removal of gutta-percha from root canals. 1. Efficacy]. / Oplosmiddelen ter verwijdering van guttapercha uit wortelkanalen 1. Efficiëntie.

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.

[HIV and dentistry. Part 5. Practice hygiene]. / HIV en tandheelkunde. Deel 5. Praktijkhygiëne.

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.