INCREASED rates of initiation and progression of various lesions after surgical removal of some or all of the principal salivary glands have been reported in the laboratory rat under a variety of conditions.'-5 Similarly, a substantial increase in susceptibility to tooth decay has been observed in Syrian hamsters and in cotton rats after the extirpation of the major salivary glands.6-8 Cheyne2 conducted an experiment to determine which of the salivary glands contributed most to the maintenance of the teeth while the rats were being fed the Hoppert-Webber-Canniff coarse particle, caries-producing diet.9The greatest severity of caries was observed in the group where the parotid and submaxillary glands had been extirpated. The present studies were undertaken to determine in greater detail to what extent relative degrees of caries could be obtained by extirpation of single pairs or combinations of pairs of salivary glands. EXPERIMENTAL Albino rats of the Sprague-Dawley strain were used in these studies. At the beginning of each of the two experiments, the animals were approximately 21 days old and weighed 35 to 50 grams. The rats were placed in individual wire cages with screen bottoms and fed the purified caries-producing ration 100 ad libitum throughout the entire experimental periods.10 In Experiment 1, the animals were divided into eleven groups consisting of eight rats each. After one week to permit adaptation to the purified ration, single pairs of salivary glands or combinations of pairs of glands were extirpated under ether anesthesia according to the schedule shown in Table I. No attempts were made to remove the minor sublingual glands which lie at the base of the tongue. At the end of fifteen weeks the animals were sacrificed by ether.To confirm the results obtained in Experiment 1, and to try to obtain information as to why the removal of combinations of glands had not produced greater increases in the caries scores than had been caused by the removal of single pairs of glands, an additional 120 white rats were obtained from the same source and wore divided into ten groups of twelve rats each. The operations were performed according to the schedule in Table II. Since there was no reason to believe that the caries scores of another group of intact rats which had been sham-operated would differ appreciably from the low caries These studies were supported to a large extent by grants-in-aid from the
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