---

Dentistry (vCJD)

I am delighted to have this opportunity to raise this rather complex and minor issue, except in the minds of dentists. That leads me to declare an interest: I am a very, very part-time dentist, but I take a considerable interest in endodontics. The reason for the debate is the letter sent by the chief dental officer for England last month to every dentist in England. I believe that a similar letter has gone out in the other countries of the United Kingdom. The letter stated that its intention was to"““clarify the situation with regard to decontamination and reuse of instruments, especially those used in endodontic treatment””." That covers an area quite a lot broader than might at first appear. Advice was given in the letter on having high standards of decontamination, which is good, logical and appropriate. A new point was introduced, however, which stated that"““endodontic reamers and files are to be treated as single use.””" The advice was intended to stop the transmission of variant Creutzfeldt-Jakob disease from carriers to non-carriers during endodontic treatment. To my surprise, it received a lot of coverage in the national media—it must have been a quiet day. As patients tend to scare easily, especially in relation to dentistry, a little reassurance might help. Variant CJD is an exceptionally rare but fatal human disease of the brain and nervous system. It was first discovered in 1996 and is considered to have originated in humans through the consumption of cattle infected with bovine spongiform encephalopathy. By mid-2006, 265 people in the UK had either definitely or probably died from the disease. Iatrogenic transmission is considered to be a remote possibility via the prion protein on surgical—especially stainless steel—instruments. To add to the scare factor, I understand that in the last financial year more than 900,000 root treatments were conducted through the national health service in England alone. As well as looking at a number of papers dealing with the subject, I discussed the situation with Professor Hugh Pennington, a renowned expert in the field. He pointed out to me, reassuringly, that occurrences of the condition appeared to be diminishing, and said that, at a guess, there were perhaps 200 carriers in the United Kingdom out of a population of 60 million. The chances of being preceded into the dental surgery by one of those 200 are therefore fairly remote. Professor Pennington made further reassuring points. He said there was no convincing evidence that vCJD had been iatrogenically transmitted to humans by surgical instruments. He thought that surgery was under some suspicion, but that that applied only to surgery on the central nervous system. Moreover, there was no evidence of iatrogenic transmission through dentistry at any time in the United Kingdom or, indeed, the world. As the Minister will know, the chief dental officer was concerned about the result of research involving mice and transmission from stainless steel endodontic instruments. That research prompted concern that the protein could be difficult to remove from stainless steel endodontic reamers and files, and hence could be iatrogenically transferred from one mouse to another. Professor Pennington considered that the normal dental wire brush cleaning, followed by autoclaving, would dramatically reduce the already tiny risk to any dental patient. However, the chief dental officer, acting on the precautionary principle, issued a warning. As the Minister probably knows, endodontics—tooth root filling or, in layman’s terms, taking out the nerve—are used as a means of preserving a tooth in its place in the jaw when it is dead or dying, or as a means of retaining or restoring a badly broken-down tooth. If the Minister does not follow that, the Chancellor will be able to explain, according to recent reports in the newspapers. The dentist locates the so-called nerve or pulp through the occlusal surface of the tooth using instruments such as diamond or tungsten carbide burs, often followed by stainless steel burs to locate the main pulp chamber. Further instruments, especially in the case of premolars and molars, are frequently used for location and opening of root canals. Locating of the openings of the canals may be difficult and may involve specialist instruments, particularly endodontic Piezo ultrasound diamond and nickel titanium instruments. Traditionally, the cleaning of the canals is undertaken with stainless steel endodontic reamers and files. More recently, the profession has moved to the use of much improved rotary nickel titanium reamers. The manufacturers suggest that they should be used on up to 10 root canals—which is just as well, as they are expensive. The advised limit is intended to reduce the risk of file separation in the canal. The alternative treatment of teeth clinically requiring root canal treatment because of disease is, of course, extraction. Interestingly, a report in the British Dental Journal at the end of last month about a research programme on dental treatment and the risk of vCJD, involving examination of patients carrying the disease, concluded"““We did not find a statistically significant excess of vCJD associated with dental treatments with the exception of extractions””." Most instruments used for extractions are stainless steel. Incidentally, so are most dental instruments, all of which at some time or other will be contaminated with blood and potentially, in some cases of dental surgery or scaling, with oral tissue. To give the Department of Health its due, I understand that it has been funding a research programme seeking a new method of prion decontamination. Last week—the timing was brilliant—the research produced, through a collaboration between D-Gen & DuPont, a new prion disinfectant called Rely+On Prion Inactivator. Only DuPont could have come up with a name like that. All those issues raise a number of questions. First, in the research on mice, was hypochlorite used, as in normal human etidodontics, as a lubricant and remover of protein tissue from instruments? Secondly, bearing in mind that stainless steel instruments are increasingly being replaced with nickel titanium, does the research on mice indicate that they as hard to clean of protein tissue as stainless steel? Thirdly, has use of the new prion inactivator been taken into account in the decision, or can it be now? Fourthly, in view of other research, why have endodontic files been specifically selected when many other surgical instruments, including other endodontic instruments, could technically be just as vulnerable? Fifthly, as national health service dentists keep asking, who will pay? Stainless steel reamers cost probably less than £10 a pack. The cost of nickel titanium kits varies between £35 and £60 a kit. We must also consider endodontic instruments that enter and touch vital pulp tissue. A dentist who frequently searches for root canals might use one, two or three ultrasonic cutters in doing so, and they cost between £70 and £85 each. Endo-access kits—to use the dental slang—which have stainless steel burs as well as tungsten carbide ones and which frequently hit the pulp because they have to go through to find the chamber, cost £40. Finally, as Professor Pennington agreed, the risks are infinitesimal. There are very few carriers. Sterilization techniques massively reduce what is already a very tiny risk to virtually no risk, especially if the new prion inactivator is used. Hence questions have to be asked about risk assessment and whether proportionality should be applied to the precautionary principle. In essence what I am asking is, can we have another think?