EFFECT OF HIBERNATION ON TEETH 289 



fected tubules extend from the surface lesion deep into the substance 

 of the dentin. In Fig. 7, a further aggravated lesion, in which the 

 dentin has been locally decalcified, has produced a typical carious 

 cavity containing a heavily stained plaque. 



Pulpal involvement is of common occurrence as demonstrated in 

 Fig. 8, which represents a buccal-lingual section of the upper first 

 molar. The carious lesion has invaded the pulpal area, and the proc- 

 ess of degenerative change has resulted in an open communication 

 with the oral cavity. The disintegration of the pulp extends into 

 the root to produce an apical abscess. The inflammatory lesion has 

 infiltrated the interradicular region and has extended to the adjacent 

 bone. In this figure the periapical abscess is pronounced. 



In an animal in hibernation for 3 months, a buccal-lingual section 

 of an upper molar (Fig. 9) demonstrates open communication of 

 the pulp with the oral cavity. In this case, the destruction of the 



Abbreviations Used in Figures 



A, abscess Ep, epithelium 



B, bone G, gingiva 



C,_ cementum IT, infected tubules 



Ca, calculus Od, odontoblastic layer 



CE, cemento-enamel junction P, plaque 



Cr, carious lesion . PA, pulpal abscess 



Cu, cuticle PP, periodontal pocket 



D, dentin Pu, pulp 

 DD, deficient dentin R, root 



E, enamel RF, root fragment 

 EA, epithelial attachment 



Fig. 1. Incisal dentin of a warm and active Arctic ground squirrel. The 

 dentin is homogeneously calcified. 



Fig. 2. Incisal dentin of squirrel in hibernation for 3 weeks. The deficient 

 dentin shows an increased number of interglobular spaces. 



Fig. 3. Upper molar of a warm and active squirrel. The compactness of the 

 interseptal and interradicular bone is normal. 



Fig. 4. Upper molar of an animal in hibernation for 3 months. Osteoporosis 

 of the spongiosa of both the interseptal and the interradicular bones is obvious. 

 Calculus is present in the interproximal gingivae. 



Fig. 5. Upper molar of an animal in hibernation for 3 weeks. From the 

 plaques in the occlusal pits heavily stained lamellae project toward the dentin. 



Fig. 6. Upper molar of an animal in hibernation for 3 weeks. The dentinal 

 tubules have become infected by carious invasion. 



