Hypoparathyroidism with decreased incretion of parathyroid hormone results in tetany, which is accompanied by a marked drop in serum calcium and a normal or elevated serum phosphorus. The tissues become depleted in calcium and develop neuromuscular irritability. In mild cases this may be evidenced by twitching, while in severe cases there are regular spasms of muscles with convulsions. The relationship of hypoparathyroid tetany to the teeth and oral structures has been the object of study and some animal laboratory experimentation by several investigators. Dental tissues, particularly dentine, are regarded as sensitive indicators in alteration of calcium metabolism.
As early as 1879 Magitot1 postulated that hypoplasia of the enamel was associated with tetany. Fleischmann2 in 1908 found parallel horizontal rows of bands superimposed around the teeth of children suffering from tetany. This was regarded as a type of enamel hypoplasia.
Erdheim3 and Toyofuku4 in 1911 made rat studies consisting of autotransplantation of parathyroid tissue, which produced changes in pulp, dentine, and enamel of the teeth. The greatest abnormality was found in the dentine. Gies and collaborators5 in 1917 confirmed these findings in similar experiments on young rats, demonstrating that parathyroidectomy, without disturbance of the thyroid, resulted in deficient calcification of the teeth without producing effects on the general formation and dimension. Schour and coworkers6 in 1937 found no retardation of eruption of the incisor teeth in albino rats. These workers demonstrated marked alteration of tooth substances appearing in the parathyroidectomized animals that survived for a long period. The alterations were particularly. . .