Dental amalgam and multiple sclerosis: a case-control study in Ferrara, Italy

Background: Epidemiological data on Multiple Sclerosis (MS) have enphasized the role of both genetic and environmental factors in the etiology. Despite the weakness of biological plausibility, dental amalgams containing mercury have been suggested as a possible risk factor. Methods: In a community-based case-control study carried out in the Province of Ferrara, we interviewed 132 MS cases with diseases onset during the last 10 years and 423 controls, to obtain information on socio-demographic characteristics and the number of dental amalgams and the time since their installation. Results: Odds ratios (OR) for subjects with exposures of different duration and with different numbers of amalgams were not statistically significant. The comparison between subjects with no fillings and those with protracted exposures to many amalgams did not give significant results. The group with exposure before 15 years of age did not seem to have larger OR than those with exposure beginning later in life. Conclusions: Neither the number nor the duration of exposure to amalgams supported the hypothesis of an increased risk ofMS, in agreement with another study carried out in Canada and addressing the same topic.