On Certain Parasites of the Mouth in Cases of Pyorrhc&a. 515 



mass of tartar which was attached to the tooth shown in fig. 4 

 dropped away altogether ; a section through the terminal branches 

 of Leptothrix colonies from its surface is shown in fig. 14. All 

 that is left in fig. 4 consists of loose clumps of Leptothrix and a 

 good deal of pus in contact with the broken epithelium. The 

 latter can be seen to be peeling off and to have already lost its 

 characteristic regular appearance. At later stages (figs. 7 and 8) 

 it disintegrates to such a great extent, and the remains become so 

 much infiltrated with deeply staining pus-cells from the lymph 

 glands, that it is almost unrecognizable. It is hardly necessary 

 to point out how much the gum has receded in the figures ; even 

 in such a mild case as that represented in fig. 4 the crusta petrosa 

 may be seen extending nearly to the top of the portion of dentine 

 shown. 



The peridontal layer may be seen in figs. 7 and 8 to have 

 become very wide and necrotic-looking. It contains pus-cells and 

 often numerous nests of nuclei which have been described as 

 epithelial remnants. With regard to these we have not at present 

 any conclusive evidence to offer. They are certainly sometimes 

 present in apparently normal jaws, and, in some cases of pyorrhoea, 

 especially in the cat, are very numerous ; but we have hitherto 

 found no micro-organisms in connexion with them, nor in fact in 

 any part of the peridontal layer. The changes which have taken 

 place in the bone of the jaw are apparent in both cases repre- 

 sented in figs. 7 and 8. The alveoli are much reduced, especially 

 in the more advanced case (fig. 8), where the alveolus on the 

 labial side has become quite flattened. On examining these 

 sections with high powers numerous osteoclasts may be seen at 

 work eating away the surface of the alveolus and also effecting 

 lacunar absorption in all directions. 



Some clinicians have objected to the name Pyorrhoea owing to 

 the absence of a " flow of pus " in some cases in which recession 

 is undoubtedly taking place. These are most interesting cases, 

 and we are convinced that tlie absence of certain symptoms is 

 only temporary and due to careful cleansing of the mouth by 

 washes, etc. Kecession in such cases is very gradual, but from con- 

 tinual observation of a few patients we are convinced that even 

 here the recession is the result of inflammation. In fact our 

 observations lead us to support the theory put forward by 

 Znamensky {16) in 1902, that pyorrhoea always begins as an 

 inflammation of the gums — so-called marginal gingivitis. Two 

 cases of sfradual recession that have come under our observation 

 may be briefly mentioned, both in persons between thirty and 

 forty years of age, whose mouths were thorouglily cleansed at least 

 twice a day. In one of these the premolars and a molar on the 

 left side showed very slight recession. From the molar the gum 

 had receded a little more at the front than at the back, which there- 



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