THE EFFECT OF PENICILLIN ON DENTAL CARIES IN RATS FED ON A COARSE CORN DIET

¹ School of Dentistry, Western Reserve University, Cleveland, Ohio

An experiment was conducted with rats fed a Hoppert diet, some of which received plain water, others the same diet with the varying amounts of penicillin in the water, and some with sucrose and penicillin added to the water. The rats were fed for 110 days. The control rats showed that 70 per cent of them developed dental caries, and in the rats receiving 5 units of penicillin per c.c. of water supply, 50 per cent had dental caries. When a weighted value was given to the carious lesions on the basis of the amount of tooth structure which was destroyed by values of 1 for incipient caries, 2 for deep caries of the dentin, and 3 for caries which involved pulp exposures, the caries control rats had a weighted value of .154 and the rats receiving 5 units of penicillin a weighted value of .135. The rats receiving sucrose showed quite a different situation. One hundred per cent of those receiving additions of 1.5 per cent of sucrose to the water had dental caries. Of the rats which received additions of 5 units of penicillin per c.c. and 1.5 per cent of sucrose to the water, 68 per cent had carious teeth. When similar weighted values were given to the carious lesions, the rats receiving sucrose additions had a caries weight of .353 and those with penicillin and sucrose a caries weight of .166. The percentage of carious teeth was also markedly reduced from 22.5 per cent in the rats receiving sucrose to 9.3 per cent in the rats receiving sucrose and penicillin.

Ingestion of penicillin in water by white rats reduced the occurrence of L. acidophilus. In those rats receiving penicillin-sucrose supplements in the water, a marked shift of the oral flora to that of B. lactis aerogenes occurred.