The Incidence of Dental Caries in Seventy-Six Monkeys *

Further knowledge concerning the spontaneous occurrence of dental caries in animals as well as in man is necessary in. order to shed more light on the etiology of this disease. The present communication reports the incidence and the clinical and histological descriptions of lesions in the teeth of monkeys.t These lesions are similar to or identical with those found in man. The dentitions of a colony of 76 monkeys (Macaca mulattat) were examined. In this group 25 had deciduous, 22 permanent, and 29 mixed dentitions. These animals were not intentionally deprived of any dietary element that might interfere with normal growth, development, or maintenance of health. During the examination the mouth was kept wide open by means of a bar of wood held between the jaws in the retro-molar regions. The surfaces of each tooth were inspected with the aid of a mouth mirror and an explorer. A tooth was considered carious when there were necrosis and debris associated with cavitation on that surface of the tooth which is exposed in the oral cavity. These same criteria were employed by the authors' in differentiating between dental caries and other lesions found in the teeth of a group of children. Defects which did not answer the requirements of this definition were not recorded as dental caries. Samples of teeth with lesions diagnosed as dental caries were removed following clinical examination, re-examined grossly, and histological preparations were made and studied. Of this group of 76 animals, three had carious lesions clinically similar to those found in man. In one of these animals (No. 17) the complete deciduous dentition and four permanent first molars were present. Dental caries was found on the distal and occlusal surfaces of the upper left first permanent molar. Animal num-