EFFECT OF HIBERNATION ON TEETH '291 



pulp has extended down into the root of the tooth. This pulpal in- 

 flammation has hollowed out the root canal, resulting in a thinning 

 of the root while the necrotic pulp fills with debris. In addition, the 

 epithelial attachment has proliferated deeply along the sides of the 

 root toward the apex, with extensive destruction of the gingiva on 

 the buccal face of the molar. 



In another animal in hibernation for 3 months, the pulpal involve- 

 ment has become so extensive as to lead to a fracturing of the coronal 

 part of the tooth (Fig. 10). The epithelium has invaded the base of 

 the fracture, and both the surface epithelium and the inflammatory 

 cells have proliferated deeply to the apex of the tooth fragments. 

 One fractured fragment has been encircled by epithelium. 



The encircling of fragments by epithelium takes place at various 

 times during hibernation, as shown in Fig. 11, which is a section of 

 a premolar from an animal in hibernation for 1 month. In this case, 

 a persistent fragment of the tooth is encapsulated by epithelium. 

 Pus cells are seen adjacent to the open end of the tooth, and the 

 epithelium has proliferated to the apical end of the fragment, form- 

 ing a deep periodontal pocket on the distal surface of the tooth frag- 

 ment. The mesial fragment from this tooth has been exfoliated, and 

 a periodontal pocket is observed on its distal surface. 



Fig. 7. Upper molar of an animal in hibernation for 1 month. The carious 

 cavity in the locally decalcified dentin is extensive. 



Fig. 8. A buccal-lingual section of an upper molar of an animal in hiberna- 

 tion for 3 weeks. The carious lesion has invaded the pulp, resulting in its open 

 communication with the oral cavity. The periapical abscess has invaded the 

 adjacent bone. 



Fig. 9. A buccal-lingual section of an upper molar of an animal in hiberna- 

 tion for 3 months. The destruction of the pulp has extended deep into the roots, 

 resulting in a thinning of the root. Downgrowth of epithelium toward the apex 

 and destruction of the gingiva on the buccal surface have also occurred. 



Fig. 10. A premolar of an animal in hibernation for 3 months. The coronal 

 part of the tooth has fractured, and the epithelium has invaded the base of the 

 fracture. 



Fig. 11. A premolar of an animal in hibernation for 1 month. A persistent 

 fragment of the tooth is encapsulated bv epithelium. The deep periodontal 

 pocket on the distal surface of the tooth fragment is indicative of extensive 

 degeneration. 



Fig. 12. The interproximal region between two premolars of an animal in 

 hibernation for 3 weeks. Pocket formation and the presence of calculus on all 

 surfaces is obvious. 



