Multiple sclerosis, dental caries and amalgam fillings — is there an association?

Key Points

In brief

• MS patients have more dental caries than age-sex matched controls. This difference is unlikely to be secondary to MS and may be causally associated in some way.

• Levels of mercury in the body are not higher in MS patients compared with controls suggesting mercury is unlikely to be a causal factor for MS.

• Levels of mercury in the body were related to the number of teeth filled with mercury.

• Further research should concentrate on the possible aetiological connection between dental disease and MS.

Abstract

Objectives To investigate the association between multiple sclerosis, dental caries, amalgam fillings, body mercury and lead.

Design Matched case-control study.

Setting Leicestershire in the years 1989–1990.

Subjects Thirty-nine females with multiple sclerosis (of recent onset) were matched with 62 controls for age, sex and general practitioner.

Methods Home interview of cases and controls within which there was an assessment of the DMFT index and blood and urine mercury and lead levels.

Results The odds of being a MS case increased multiplicatively by 1.09 (95% CI 1.00,1.18) for every additional unit of DMFT index of dental caries. This represents an odds ratio of 1.213 or a 21% increase in risk of MS in relation to dental caries in this population. There was no difference between cases and controls in the number of amalgam fillings or in body mercury or lead levels. There was a significant correlation between body mercury levels and the number of teeth filled with amalgam (controls: r = +0.430, P = 0.006, cases: r = +0.596, P = 0.001).

Conclusion There was evidence of excess dental caries among MS cases compared with the controls. This finding supports the strong geographical correlation between the two diseases. A further study of this association is recommended.

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