The purpose of this study is to determine whether there are detectable health effects of low-level mercury exposure (from normal exposure to mercury-containing dental fillings) in the known target organs/systems affected by elemental mercury exposure.

The Casa Pia Study of the Health Effects of Dental Amalgam in Children is a randomized, prospective clinical trial with the overall goal of determining if there are detectable health effects due to exposure from mercury-containing dental amalgam fillings. Children, thought to be the population most susceptible to any possible health effects, were randomly assigned to one of two treatment groups (total n=507). Subjects were originally enrolled at ages between 8-10 years of age. To participate, subjects must have: Dental caries in at least one posterior tooth; no prior exposure to dental amalgam; a blood lead of <15ug/L; a urinary mercury level of <10ug/L; an IQ as measured by the CTONI of >67; and no prior or existing serious medical or neurologic condition. One group received only dental filling materials other than those containing mercury (plastic and ceramic composites), while the other group received mercury amalgam fillings where appropriate (in large restorations in back teeth), but the alternative materials everywhere else. Both treatment regimens are standard-of-care throughout the world. Subjects receive ongoing dental care via the study clinics, and continue to receive dental fillings as needed based on group assignment. The target organs of mercury exposure are renal and neurological. Baseline and annual repeated measures are taken on all subjects for renal function, nerve conduction velocity and a large battery of neurobehavioral tests. Follow-up is planned for a period of 7 years

• Age 8-10 years of age
• Dental caries in at least one posterior tooth.
• No prior exposure to dental amalgam
• Blood lead of <15ug/L
• Urinary mercury level of <10ug/L
• IQ as measured by the CTONI of >67
• No prior or existing serious medical or neurologic condition