The widespread use of amalgam surfaces can be attributed to their low cost and high durability compared to other types of surfaces. However, the use of dental amalgams has always been a source of controversy because of the potential health risks associated with exposure to mercury. The objective of this study was to quantify the relationship between number of dental amalgam surfaces and urinary mercury levels as needed for the duration of the 3-year trial in children.
Two elementary school children in Daegu, Korea, 1-4 of grade at baseline, participated in a clinical trial to evaluate the urinary mercury concentration. Two of the trained dentists had oral examination all the teeth to check the decayed, missing, and filled surface index (ds, fs, dfs/DS, FS, DMFS) and all of the dental materials used. Urine samples were collected at baseline and at each follow-up visit. Urine samples were analysed for U-Hg levels (measured in ㎍/g creatinine). All the collected data were analyzed using t-test, ANOVA, χ2-test and mixed-model analysis.
During the 3-year trial period, urinary mercury levels were higher in participants with amalgam surfaces. In mixed models, amalgam surface exposure was associated with a 0.03 ㎍/g creatinine increase in current and cumulative U-Hg excretion. However, fish consumption not associated with urinary mercury levels. Urinary mercury concentration according to gender was more higher girls than boys. Total 363 of baseline and 4th follow-up finished, children who had not amalgam exposure at baseline were highly level of urinary mercury concentration more exposure amalgam newly. Mean urinary mercury concentration at immediately and 24 hours after removal of amalgam restorations signigicant increased consistently.
This study was the first to longitudinally evaluate the associations between dental amalgam exposure and U-Hg excretion in children. Amalgam restoration was related to urinary mercury concentration, and these finding presents possibility of mercury accumulation in body. Therefore, we suggest cohort study in future and need to ensure the safety of exposure to mercury from children by establishing criteria of amalgam exposure.