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.