THE TEETH. 659 



independently of the bony alveolus. These formations bear a close resem- 

 blance to embryonal bone viz. : contain a large number of irregular bone- 

 corpuscles with broad offshoots, and a comparatively small amount of bony 

 basis-substance. On the periphery of isolated bony formations we can often 

 distinguish the medullary elements (osteoblasts), which participate in the 

 formation of bone by being partly transformed into basis-substance. 



Lastly, true bony new formations may occur on the wall of the alveolus, 

 which, after repeated attacks of pericementitis, as clinical observation 

 teaches, is sometimes beset with thorny new formations of bone. These 

 exostoses originate on the socket" of the tooth from the medullary tissue, in 

 the same manner in which exostoses grow on any other bone, as sequelae of 

 periostitis and osteitis. In the highest degree of development, such exostoses 

 of the socket replace the pericementum to such an extent that only traces 

 "of the pericementum are left. No instance, however, at least to my knowl- 

 edge, has been observed of a complete fusion of the socket with the tooth. 



Pyorrhoea Alveolaris. Surgeons have long been aware of the fact that sup- 

 purative periostitis is the main, if not the only cause of necrosis of bone ; 





r-C 



FIG. 289. GLOBULAR BODY, RESULT OF PERICEMENTITIS. 



G, concentrically striated mass, surrounded by small, spindle-shaped elements, holding a 

 star-shaped bioplasson body in its center ; C, cernentum ; M, multinuclear body, from which 

 a globular body may originate ; JE, inflammatory elements, crowded in the pericementum. 

 Magnified 200 diameters. 



thus, also, the consequence of suppurative pericementitis is necrosis of the 

 alveolus, varying in accordance with the degree of the suppuration. No cure 

 of the suppuration is possible until the necrotic parts of the bone have been 

 eliminated from the body, either spontaneously or by surgical interference. 



Under the microscope, the first stages of suppurative pericementitis are 

 identical with those of the plastic form viz. : there are nests of inflammatory 

 corpuscles between bundles of unchanged connective tissue. The less, there- 

 fore, of this connective tissue is left, the more numerous the inflammatory 

 elements are, the nearer is the tissue to suppuration. 



