294 W. V. MAYER AND S. BERNICK 



tears on tlie distal surface of the molariform tooth are obvious. A 

 periodontal pocket with a proliferating epithelial attachment is pres- 

 ent in the gingivae of the same surface. A pulpal abscess is present 

 and its communication with the oral cavitv is noticeable. 



The interproximal region between two molars from another hil^er- 

 nating squirrel shows a downgrowth of the epithelial attachment, 

 which proliferates into the interradicular area (Fig. 15). The in- 

 vasion of the epithelium into the bifurcation region is accompanied 

 by a disorganization of the attachment fibers and a lowering of the 

 alveolar bone. This degeneration is accompanied bv carious lesions 

 of the dentin. 



In Fig. 16, showing a first upper molar of a squirrel in hibernation 

 for 3 months, continued deterioration is demonstrated. Periodontal 

 pockets on the mesial and distal surface exhibit such extensive bi- 

 furcation invohement that no bone remains in the interradicular 

 region. In addition, an apical abscess is present and there is an in- 

 flammatory invasion of surrounding connective tissue. Epithelial 

 encapsulation of tooth fragments is frequently noted in squirrels in 

 hibernation. Figure 17 shows a root fragment fullv encapsulated bv 

 epithelium. 



There can be no doubt that hibernation has a dramatic eftect on 

 bone, dentinogenesis, and dental caries. The reasons why this should 

 be so, however, are not elucidated in the literature. In the work of 

 Willet et al. (1957) it was indicated that protease may accelerate 

 caries in several ways. The work of Hunt et al. (1957) showed that 

 submaxillary gland extracts of caries-susceptible rats had 5j times 

 the protease activity of gland extracts from more resistant animals. 

 The work of Mayer and Bernick, however, demonstrated an involu- 

 tion of the salivary glands during hibernation and thus an inhibi- 

 tion of protease activity. Thus, it is not to the salivaries that we can 

 turn for our explanation of aggravated carious lesions during hiber- 

 nation. 



Rosen et al. (1957) indicate that it is highly probable that micro- 

 organisms are the immediate causes of dental caries. During hiberna- 

 tion, however, there is not only a lowered oral cavit\' temperature, 

 but also a drier oral environment, due to cessation of salivary ac- 

 tivity. Thus, one would be led to anticipate less and not more mi- 



