Effect of zinc on rat mandibles during growth.

Zinc is a constituent of enzymes such as alkaline phosphatase and is an essential trace element involved in bone formation. The purpose of this study was to examine the effects of low levels of zinc intake on bone density and the area of cortical and trabecular bone in rat mandibles during the growth stage with peripheral quantitative computed tomography. The cartilaginous ossification in the femur was also measured. In the mandible, the low-zinc group showed significantly lower trabecular bone density compared with the control group, whereas the zinc-deficient group showed significantly lower levels of cortical bone density and trabecular bone density in the area. On the other hand, in the femur, both the zinc-deficient group and the low-zinc group showed a significantly lower value in cortical bone density and trabeculae bone density when compared with those of the control group. Moreover, the area of cortical bone and trabecular bone in the zinc-deficient group showed significantly lower values than those of the control group, whereas the low-zinc group only showed a significantly lower area of cortical bone than that of the control group. These results suggested that changes in zinc intake might exert an effect on the osseous tissue of the mandible and femur, and the femur was more sensitive to change of dietary zinc content than mandibles.