THE EFFECTS OF ASCORBIC ACID DEFICIENCY ON THE TEETH AND PERIODONTAL TISSUES OF GUINEA PIGS

¹ Division of Dental Research, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada

Observations have been made of the teeth and jaws of guinea pigs fed a basal semisynthetic diet supplemented with pure ascorbic acid at levels of 0.0, 0.4, and 5.0 mg. per day per animal for various periods of time. Pair- feeding methods were used as a control.

In animals fed 5.0 mg. ascorbic acid per day, whether fed ad libitum or pair-fed to one of the deficient groups, no microscopic alterations were visible in any of the tissues.

In guinea pigs fed a diet containing 0.4 mg. ascorbic acid per day, severe alterations in the structure of dentin were observed, and mild alterations occurred in the normal pattern of bone deposition and resorption in the jaws. The latter changes were not visible after 45 days' feeding but were seen after 75 days' feeding.

Tissue changes caused by feeding 0.4 mg. ascorbic acid per day for 48 days were reversed by feeding 5.0 mg. per day for an additional 27 days.

Animals kept on a diet completely deficient in the vitamin showed the most severe alterations from normal. Areas of hemorrhage occurred in both the pulp and periodontal membrane. There was a failure of connective tissue formation of collagen fibers, cementum, dentin, and bone. Excessive resorption of bone occurred and was greatest in areas where pressure normally occurs on the bone.

Enamel matrix failed to form in areas where predentin did not form. Cells of the stratum intermedium of the enamel organ proliferated at a level on the tooth far apical to that at which such proliferation normally occurs. In some areas, a cornified layer was formed. This proliferation of stratum intermedium cells created the illusion that cells of the oral epithelium had migrated down the side of the tooth.