Multiple sclerosis, dental caries and fillings: a case-control study.

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.