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Mercury from dental "silver" tooth fillings impairs sheep kidney function
N D Boyd1, H Benediktsson, M J Vimy
1Department of Pathology, Faculty of Medicine, University of Calgary, Alberta, Canada.
The American Journal of Physiology
|October 1, 1991
Summary
Dental amalgam fillings release mercury (Hg) vapor, which accumulates in sheep kidneys. Amalgam placement significantly reduced kidney function, indicated by decreased inulin clearance and altered urine composition, despite normal renal histology.
Area of Science:
- Nephrology
- Toxicology
- Dental Materials Science
Background:
- Dental amalgam, containing 50% mercury (Hg) by weight, releases Hg vapor in humans.
- Previous research indicates that sheep kidneys concentrate Hg from amalgam fillings.
Purpose of the Study:
- To evaluate the impact of dental amalgam fillings on renal function in sheep.
- To assess changes in kidney function markers following amalgam placement.
Main Methods:
- Six adult female sheep received 12 occlusal amalgam fillings; two control sheep received glass ionomer fillings.
- Renal function was assessed via plasma clearance of inulin and analysis of urine and plasma electrolytes, urea, and proteins at baseline, 30, and 60 days post-placement.
Main Results:
- Amalgam placement significantly reduced mean plasma inulin clearance from 69.5 ml/min to 32.3 ml/min at 30 days and 27.9 ml/min at 60 days (p<0.05).
- Control sheep showed no change in inulin clearance.
- Amalgam-treated sheep exhibited decreased urine albumin concentration and increased urine sodium (Na+) concentration by 60 days post-placement.
Conclusions:
- Dental amalgam fillings impaired renal function in sheep, evidenced by reduced glomerular filtration rate and altered tubular handling of sodium and albumin.
- Despite functional changes, renal histology remained normal, suggesting early or subtle nephrotoxicity from mercury exposure.