Zinc and copper in bone and teeth of mice

Zinc and copper levels of femurs, incisors and molars of mice having a normal, optimal supply of the metals were recorded at the ages of 120 and 210 days. At both ages Zn‐leveis were highest in molars, while femur levels were higher than those of incisors. In all three tissues there was a statistically significant decrease with age. Cu‐levels were highest in molars, and incisor‐levels were higher than those of femurs. In femurs and incisors the Cu‐levels were about double with age, while the increase was more than five‐fold in molars. Fourteen mice had combined additional supply of 500 μgZn/g and 200 μg Cu/g in drinking water. Seven of them were killed at the age of 120 days. Seven of them were returned to normal supply of the metals at the age of 120 days and were killed at the age of 210 days. The first seven had slightly higher Zn‐levels than control mice in femurs and incisors, while molar‐Zn was more than doubled. In the older mice that previously had had additional metal supply, this higher molar‐Zn level remained unchanged, whereas femur‐ and incisor‐Zn had returned to the levels of the youngest controls. In all 14 mice that had received hyperoptimal metal doses, hard tissue Cu‐levels were unaffected and were similar to those of controls at both ages. It was concluded that deciduous human teeth can be used as indicators of hyperoptimal Zn‐absorption, but they will perhaps not indicate hyperoptimal Cu‐absorption.