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Multiple sclerosis, dental caries and fillings: a case-control study C. W. McGrother, C. Dugmore, M. J. Phillips, N. T. Raymond, P. Garrick, and W. O. Baird Br Dent J 1999; 187: 261–264

Comment

There are occasions when the dental profession groans audibly at yet another media disinformation campaign perhaps linking cancer and Down Syndrome with water fluoridation — or indeed linking multiple sclerosis with amalgam restorations. However, it behoves us all, as scientists, to examine the facts, sift the evidence, and keep an open mind until there is sufficient robust information before we authoritatively advise our patients. Perhaps you remember the publicity of the 'miracle cures' reported in patients with multiple sclerosis after having all their amalgam fillings replaced. Perhaps, like me, you thought that MS is a disease which is characterised by remissions and relapses and patients were clutching at straws in the vain attempt to produce a miracle.

This research project investigates the emotive argument in a very scientific approach so that we can produce some evidence-based dentistry as far as MS sufferers are concerned. The subjects and controls were identified according to rigorous criteria but although, there was a response rate of 81% in the MS study group there was a lower 59% response rate in the matched control group. It is, perhaps, important to note that there was a tendency for the MS cases to be relatively disadvantaged in relation to employment and major financial commitments to home and car ownership despite similar levels of educational attainment.

As far as the dental findings were concerned, there was a significant relationship between MS and dental caries with a mean difference of 2.24 carious teeth between MS cases and controls. What is also very important is that there was no significant difference in the number ot teeth filled with amalgam. There was evidence, though, of wholesale replacement of fillings with non-amalgam materials in four of the MS cases.

However, is this cause and effect? The old, old question of which comes first — the chicken or the egg, must come to mind. Should we postulate that the differences in dental caries arose after the onset of MS because of all sorts of compensatory dietary factors, or as a result of its debilitating nature? Or does Streptococcus mutans have an important effect on the activation of the immune mechanism involved in demyelination in MS as well as dental caries?

There are very important conclusions that we can draw from this study. First that there is a correlation between multiple sclerosis and dental caries. Secondly, there is no association between multiple sclerosis and the numbers of amalgam fillings or body mercury. Thirdly, without doubt, we still have many more questions to answer in this field but this research project has furthered our evidence base in advising our patients.