THE TEETH. 661 



but largely provided with irregular protrusions, or papillary outgrowths of 

 a myxomatous structure, crowded with inflammatory elements. The sac 

 contains inspissated pus, which, upon the cutting of microscopical sections, 

 crumbles away. 



Cementitis and osteitis always accompany an alveolar abscess. Cementitis 

 leads to a destruction of the cementum in the shape of deep, irregular, bay- 

 like excavations, which exhibit all stages, from the liquefaction of the basis- 

 substance up to the transformation of the living matter into pus-corpuscles. 

 Sometimes the excavations penetrate the dentine. In the highest degrees of 

 pericementitis the apex of the root, inclosed in the alveolar abscess, is trans- 

 formed into a thin, jagged, and corroded stump, with but scanty remnants of 

 the former cementum. 



Osteitis (inflammation of the wall of the alveolus) is an inevitable result of 

 the formation of an alveolar abscess. The portion of the socket in contact 

 with the sac of the abscess is widened, its surface being either smooth or 

 jagged. Examination with the microscope leaves no doubt that the inflamma- 

 tory elements, sprung from the bony tissue after dissolution of its lime-salts 

 and liquefaction of its gluey basis-substance, become spindle-shaped, and 

 participate largely in the formation of the wall of the abscess. 



Literature. In regard to the literature of pericementum and pericementitis 

 I have but little to say, as this subject has been very much neglected by 

 nearly all histologists. I shall quote from a few only of the modern authors. 

 Carl Wedl* says: u Generally the root-membrane, or periosteum of the 

 root, is of moderate density ; the bundles of connective tissue forming it con- 

 tain no elastic fibers, and inclose fusiform connective-tissue corpuscles ; in 

 addition to these, roundish elementary organs are met with." 



According to E. Magitot,t " the root-membrane consists of two portions: 

 an inner, which does not admit of being teased into fibrils ; and an outer, lying 

 near the alveolar wall, which has the appearance of a fibrous structure. The 

 same writer also mentions the occurrence of ' cellules myeloplaxes,' similar 

 to those found in the periosteum of bone, and cytoblastions (nuclei invested 

 with a layer of protoplasm), which occur still more rarely." " The changes 

 in the hard tissues of the root, which occur chiefly with chronic suppurating 

 inflammation of the periosteum of the root, consist in necrosis and resorption, 

 according to the nature of the tissue." "The histological appearances pro- 

 duced by the process of resorption are displayed in a manner similar to those 

 which were observed in the resorption of the roots of the milk-teeth i. e., 

 there are circumscribed depressions upon the outer surface of the cement, 

 which are made up of groups of closely approximated, shallow, cup-shaped 

 indentations. In the ridge-like elevations which bound the excavations well- 

 preserved bone-corpuscles are to be found, while they become gradually less 

 discernible in the deeper portions. Necrosis of the cement not infrequently 

 is associated with resorption." "If the cement is entirely destroyed here and 

 there by the suppuration, the dentine becomes similarly affected, and acquires 

 a roughened or corroded appearance." " There are no indications of a vital 

 action on the part of the dentine. The theories advanced to explain the 

 manner in which the excavations are produced by resorption are mere sup- 

 positions ; they may be regarded as induced either by the activity of the pus- 



* " Pathology of the Teeth," Philadelphia, 1872. Page 59. 

 t " Memoires sur les Tumeurs du Perioste Dentaire." 1868. 



