Variant Creutzfeldt-Jakob Disease—A Problem for General Dental Practitioners?

Abstract

Over a hundred deaths from variant Creutzfeldt-Jakob disease (vCJD) have now been recorded. The incubation period for vCJD may be up to 40 years and the number of asymptomatic carriers in the population could be as many as 100,000. Confirmed iatrogenic transmission of other human transmissible spongiform encephalopathies raises the possibility of cross-infection from apparently healthy persons who are incubating vCJD. Decontamination techniques routinely used in general dental practice are incapable of inactivating the infective protein responsible for transmitting the disease. So far, no evidence exists to preclude the risk of iatrogenic infection occurring during dental procedures. The author reviews present knowledge of the infective agent, its transmissibility, its origins, current guidelines and the implications for dental practice.

Investigation of PrPres in dental tissues in variant CJD

“…32 Since the distribution of infectivity in the sheep model of experimental BSE is similar to that in variant CJD, this finding has reinforced concerns about potential infectivity in blood in variant CJD, which have been addressed in various precautionary measures by the national blood authorities in the UK. The significance of prion infectivity in tonsils for dental surgery has been considered in recent reviews; 17,18,31 recent measures from the Department of Health to improve standards of cleaning and decontamination of surgical instruments are likely to help reduce these risks, even given the difficulties associated with decontamination in prion disease. 31,33 The results of ongoing research into means of improving decontamination and cleaning techniques for surgical instruments is awaited with interest, as these are likely not only to help reduce risks of variant CJD transmission, but also the risks of transmission of other infectious agents via surgical instruments.…”

“…13,14 However, the accumulation of PrP res in variant CJD tissues is more widespread than in sporadic CJD, 4,5,13,15 suggesting a greater potential risk of secondary disease transmission by contaminated surgical instruments since prion infectivity is notoriously resistant to standard forms of decontamination. 16,17,18 Although there is little evidence to suggest that dental surgery is a risk factor for sporadic or iatrogenic forms of CJD, 2,19 the potential risk of secondary transmission of variant CJD posed by dentistry is currently unknown. 17,18 Infectivity in dental tissues has been described in a rodent model of scrapie, 20 and experimental inoculation of infected brain homogenate into the tongue and into dental pulp appears to be an efficient route of neuroinvasion.…”

“…16,17,18 Although there is little evidence to suggest that dental surgery is a risk factor for sporadic or iatrogenic forms of CJD, 2,19 the potential risk of secondary transmission of variant CJD posed by dentistry is currently unknown. 17,18 Infectivity in dental tissues has been described in a rodent model of scrapie, 20 and experimental inoculation of infected brain homogenate into the tongue and into dental pulp appears to be an efficient route of neuroinvasion. 21 However, PrP res was undetectable in dental pulp samples from patients with sporadic CJD.…”

The availability and content of dental instrument manufacturers' decontamination information

“…3,7 The range of modern dental instruments is vast and the degree of complexity has increased with technological advances. In addi tion, the range of cleaning materials and equipment has increased markedly over recent years.…”