A SURVEY OF THE INCIDENCE OF DENTAL CARIES IN THE RHESUS MONKEY

¹ Department of Biochemistry, College of Agriculture, University of Wisconsin, Madison, Wis.

A survey of the frequency of dental caries incidence in 138 rhesus monkey skulls is reported. The incidence of obvious carious lesions was determined by observation of the intact surfaces of the teeth. The frequency of caries incidence observed was higher than has been reported previously. The monkeys had been maintained for periods varying from a few days to 3 years on various nutritionally adequate and deficient rations. The frequency of caries incidence increased with the length of time the monkeys were maintained on these dietary regimens.

In order to detect all the carious lesions which were present, it was shown that the teeth must be examined by grinding in order to observe successive planes parallel to the occlusal surface. Only in this way can all the lesions at the base of the sulci and in the developmental fissures be seen and evaluated. In each group of monkeys the frequency of caries incidence, when determined by this method, was higher than when determined by inspection of the intact surfaces of the teeth.

The carious lesions observed in the rhesus monkey are very similar to those found in man. A definite, bilaterally symmetrical distribution was found. However, the caries incidence in the upper was higher than in the lower jaw.

The susceptibility of the rhesus monkey to tooth decay observed in this survey is sufficiently high to warrant the extensive use of this species in dental caries research. The high susceptibility reported is apparently due to the type of dietary regimen. It would appear from the data at hand that diets which contained high amounts of sucrose produced a greater frequency of dental caries in the monkey than natural rations. Thus, the rôle of nutrition assumes a vital relation in the production of or prevention of dental caries. However, a period of at least 2 years is necessary for the satisfactory assay of the effect of any causative or preventive treatment upon the frequency of caries incidence in the monkey.