AJP - Regulatory, Integrative and Comparative Physiology, Vol 261, Issue 4 1010-R1014, Copyright © 1991 by American Physiological Society
Mercury from dental "silver" tooth fillings impairs sheep kidney function
N. D. Boyd, H. Benediktsson, M. J. Vimy, D. E. Hooper and F. L. Lorscheider
Department of Pathology, Faculty of Medicine, University of Calgary, Alberta, Canada.
In humans Hg vapor is released from "silver" amalgam fillings that contain
50% Hg by weight. Previous studies show that when 12 such fillings are
placed in sheep teeth, the kidneys will concentrate amalgam Hg at levels
ranging from 5 to 10 micrograms Hg/g renal tissue 4-20 wk after placement.
In the present study 12 occlusal fillings were placed in each of six adult
female sheep under general anesthesia, using standard dental procedures.
Glass ionomer occlusal fillings (12) were inserted in two control sheep. At
several days before dental surgery, and at 30 and 60 days after placement
of fillings, renal function was evaluated by plasma clearance of inulin and
by plasma and urine electrolytes, urea, and proteins. An average plasma
inulin clearance rate of 69.5 +/- 7.2 ml/min before amalgam placement was
reduced to 32.3 +/- 8.1 ml/min by 30 days and remained low at 27.9 +/- 8.7
ml/min after 60 days. Inulin clearance did not change in controls. After
amalgam placement urine concentration of albumin decreased from 93.0 +/-
20.5 to 30.1 +/- 15.3 mg/l and urine Na+ concentration increased steadily
from 24.8 +/- 7.7 to 82.2 +/- 20.3 mmol/l at 60 days. Concentrations of K+,
urea, gamma-glutamyl transpeptidase, alkaline phosphatase, and total
protein did not change significantly from 0 to 60 days in urine. Plasma
levels of Na+, K+, urea, and albumin remained unchanged from 0 to 60 days
after amalgam. Renal histology remained normal in amalgam-treated
animals.(ABSTRACT TRUNCATED AT 250 WORDS)
