The effect of diets deficient in calcium or phosphorus in the presence and absence of supplements of vitamin D on the incisor teeth and bone of adult rats

Abstract

Groups of adult rats were for 20 weeks given diets deficient in calcium, or phosphorus, or vitamin D, or calcium and vitamin D or phosphorus and vitamin D. Serum calcium concentrations were not lowered by any of the dietary treatments and were raised significantly by diets low in phosphorus. Serum phosphate concentrations were significantly lowered when the diets were low in calcium or phosphorus or vitamin D. Diets low in calcium caused no demonstrable histological or microradiographic changes in the femur. A double deficiency of calcium and vitamin D resulted in slight irregularity of the epiphyseal disc in some animals. Low calcium diets produced femora in which the shaft appeared slightly thinner. Diets deficient in phosphorus, or phosphorus and vitamin D caused some disturbance in the femur, a few osteoid seams were observed, the shaft appeared thinner and there was qualitatively more variation in the density of the microradiographs. Lack of dietary calcium caused a significant reduction in bone mass and weight of ash; the slight fall in the percentage of ash was of doubtful significance but the ratio of weight of ash to weight of fat-free non-mineral ( A : R) was significantly less. Lack of dietary phosphorus caused small but highly significant reductions in bone mass, ash weight, percentage of ash and A : R ratio. Lack of vitamin D appeared to reduce the loss in weight of bone ash caused by diets low in calcium or phosphorus but the effect was significant in the latter case only. Lack of calcium caused a significant reduction in tooth weight whereas lack of phosphorus did not. In no case was the reduction in percentage of ash significant. Vitamin D had a greater effect on tooth weight than on bone weight. The incisor teeth showed the greatest histological and microradiographic changes when the diets were deficient in phosphorus or phosphorus and vitamin D. Diets lacking either calcium or phosphorus caused the appearance of cavities within the alveolar bone adjacent to the incisor tooth. In the adult rat the developing incisor teeth reacted differently from the long bones in response to dietary deficiency of calcium, phosphorus and vitamin D.