Accumulation and influence of mercury released from dental amalgam in living body

进行这项研究是为了获得有关牙科汞合金释放的汞在活体体内积累和影响的信息。为了解决这个问题，我们采用了一个实验动物模型，怀孕的大鼠接受汞合金牙齿填充物。我们测量了母亲和胎儿器官和血液样本中的总汞含量。本研究所得结果总结如下：实验1。汞合金牙齿修复后，汞合金汞出现在母体和胎儿器官中。在母亲中，实验组的大脑、肝脏、肾脏和胎盘的汞浓度明显高于对照组，其中肾脏的汞含量最高，其次是胎盘、肝脏和大脑。在胎儿中，来自实验组的大脑和肝脏的汞浓度明显高于对照组。胎儿器官中汞浓度最高的是肝脏，其次是肾脏和大脑。实验2。随着汞合金填充物数量的增加，母亲和胎儿器官中汞浓度有升高的趋势，而胎儿体重有下降的趋势。实验3。为观察汞合金充填物对胎儿生长发育的影响，采用玻璃离子水门铁代替汞合金充填4颗牙。在母鼠中，实验动物的生长曲线低于对照动物。在怀孕早期，饮食和水的摄入量明显低于对照组。两组胎儿体重虽无显著差异，但均低于对照组。这些结果表明，牙科治疗本身似乎影响了怀孕早期饮食和水的摄入量，并减缓了母鼠及其胎儿的生长。本研究的这些发现和实验2的结果表明，汞合金填充物本身可能并不影响胎儿的生长。实验4。本研究旨在探讨妊娠大鼠汞合金填充物与第二代和第三代后代器官中汞浓度的关系。第二代实验动物的脑、肝、肾、脾汞含量均高于对照组，但差异不显著。在第三代，汞浓度在实验组和对照组之间几乎相同。实验5。本实验旨在研究汞在母鼠及其胎儿器官中积累的化学形式。母鼠全血、红细胞和血浆中汞含量均显著高于对照组。在胎儿中，实验动物全血中的汞含量明显高于对照组。实验动物的胎母比、红细胞和血浆比均低于对照组。另一方面，实验组的PF比率高于对照组。元素汞进入胎儿后的化学转化尚不清楚，尽管有人认为元素汞经历了与母性动物相似的氧化过程。红细胞和血浆中汞浓度的比率取决于汞化合物的化学形式；接触汞蒸气后，红细胞中的汞含量比血浆中的汞含量高，但接触无机汞后，情况正好相反。在本实验中，实验组母亲的红细胞与血浆比率显著低于对照组。这表明存在于血液中的化学形式可能是无机的。在胎儿器官中，从胎盘返回的血液通过脐静脉通过静脉导管进入胎儿循环，主要通过肝脏。此外，我们知道过氧化氢酶有很大的能力将汞蒸气氧化成离子汞，而且这种酶在肝脏中含量丰富。通过胎盘屏障的汞的化学形式可能是单质的。虽然我们无法检测胎儿血液样本中红细胞和血浆的汞浓度比，但胎儿循环系统中的汞可能是无机的，因为肝脏中汞含量最高。因此，极有可能从牙汞合金填充物中释放的一部分汞通过胎盘被氧化成胎儿肝脏中的离子汞并在该器官中积累。少

This study was carried out to obtain information regarding the accumulation and influence of mercury released from dental amalgam in a livin body. To address this object we have employed an experimental animal model in which pregant rat received amalgam tooth fillings. We measured a total mercury in organs and blood samples of mother and their fetus. The results obatined in this study were summarized as follows.Experiment 1.Mercury from dental amalgam appeared in maternal and fetal organs after amalgam tooth restorations in the mother rtas. In mothers, the mercury concentrations of the brains, livers, kidneys and placentas from the experimental group were significantly higher than those of the controls, and the highest mercury was found in the kidneys, followed by placenta, liver and brain. In fetuses, the mercury concentrations of the brain, liver from the experimental group were significantly higher than those of the controls. The highest mercury concentration among fetal organs was … More found in liver, followed by kidneys and brain.Experiment 2.With the increasing number of amalgam fillings, mercury concentrations in organs of mother and their fetuses tended to increase, while body weight of fetus tended to decrease.Experiment 3.In order to examine the influence of amalgam fillings on growth of fetuses, 4 teeth were fillied with the glass ionomer cement instead of amalgam. In mothers, growth curves of the experimental animals was lower than that of the control animals. Intake of the diet and water were significantly lower than those of the controls at the early pregnant stage. Althogh, significant difference was not observed, body weight of the fetus was lower than that of the controls. These results indicated that dental treatment itself seemed to influence the intake of the diet and water at the early pregnant stage and to slow the growth of mother rats and their fetuses. These findings of this study and the results of the experiment 2 suggested that it was likely that amalgam fillings themselves did not influence the growth of fetuses.Experiment 4.This study was carried out to examine the relation between amalgam fillings in pregnant rats and marcury concentrations in organs of offspring's of second and third generations. The mercury contents in the brain, liver, kidney and spleen of the experimental animals of the second generation were higher than those of the controls, although significant differences were not observed. In the third generation, mercury concentrations were almost the same between experimental and control groups.Experiment 5.This expriment was carried out to examine the chemical form of mercury accumulated in organs of mother rats and their fetuses. In mothers, the mercury contents in the whole blood, erythrocyte and plasma of the experimental animals were significantly higher than those of the controls. In fetuses, the mercury contents in the whole blood of the experimental animals were significantly higher than that of the controls. Fetus to mother ratio, and Erythrocyte and plasma ratio of the experimental animals were lower than those of the controls. On the other hand, PF ratio of the experimental group was higher than that of the control group. Chemical transformation of elemental mercury after introduction into fetuses remains unclear, though it is suggested that elemental mercury undergoes an oxidation process similar to that occurring in maternal animals. Ratios of mercury concentrations in erythrocytes and plasma depend upon the chemical forms of mercury compounds ; after mercury exposure to mercury vapor, more mercury is found in red cells than in the plasma, but after inorganic mercury exposure, the reverse is true. In this experiment, the erythrocyte to plasma ratio of mothers of the experimental group was significantly lower than that of the control group. This indicates that the chemical form existing in the blood stream is possibly inorganic. In the fetal organs, blood returning from the placenta through the umbilical veins enters fetal circulation through the ductus venosus, mainly by passing through the liver. Furthermore, it is known that catalase has a great capacity to oxidized mercury vapor into ionic mercury and that this enzyme is contained abundantly in liver. The chemical form of mercury passing through the placental barrier is possibly elemental. Although we could not examined the mercury concentration ratio of erythrocytes and plasma in the blood sample of the fetus, mercury in the fetal circulation system is possibly inorganic because the highest mercury accumulation was found in the liver. Consequently, it is most likely that part of the mercury released from the dental amalgam filling passing the placenta is oxidized into ionic mercury in fetal liver and accumulates in that organ. Less