Specific anti cross-infection measures may help to prevent viral contamination of dental unit waterlines: a pilot study.

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

Patient notification exercise following a dentist's admission of the periodic use of unsterilized equipment.

During 2001, Greater Glasgow National Health Service (NHS) Board undertook a patient notification exercise in a Glasgow dental practice following the admission, by the dentist, of the use of unsterilized dental equipment on patients. Four thousand and eighty-nine exposed patients were identified; of these, 1696 contacted the NHS helpline and 1005 were counselled and screened for hepatitis C virus (HCV), hepatitis B virus (HBV) and human immunodeficiency virus. One patient showed evidence of previous HBV infection and 13 had antibodies to HCV. Molecular investigation of the HCV isolates indicated no significant associations. The investigation found no evidence of patient-to-patient transmission of HCV among patients attending the practice of a dentist who admitted periodically using unsterilized equipment.

Plasma cleaning of dental instruments.

The theoretical risk of prion transmission via surgical instruments is of current public and professional concern. These concerns are further heightened by reports of the strong surface affinity of the prion protein, and that the removal of organic material by conventional sterilization is often inadequate. Recent reports of contamination on sterilized endodontic files are of particular relevance given the close contact that these instruments may make with peripheral nerve tissue. In this paper, we report the effective use of a commercial gas plasma etcher in the cleaning of endodontic files. A representative sample of cleaned, sterilized, files was screened, using scanning electron microscopy and energy-dispersive X-ray analysis, to determine the level of contamination before plasma cleaning. The files were then exposed for a short-term to a low-pressure oxygen-argon plasma, before being re-examined. In all cases, the amount of organic material (in particular that which may have comprised protein) was reduced to a level below the detection limit of the instrument. This work suggests that plasma cleaning offers a safe and effective method for decontamination of dental instruments, thus reducing the risk of iatrogenic transmission of disease during dental procedures. Furthermore, whilst this study focuses on dental files, the findings indicate that the method may be readily extended to the decontamination of general surgical instruments.

[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.