CARIES DUE TO THE ACTION OF AJST ACID. 301 



organic, 61 per cent., inorganic, 39 per cent. Second slice Middle, 

 water not determined, because no longer reliable. (The specimen 

 had become a little dry.) Organic, 55.8 per cent, inorganic, lime- 

 salts, 44.2. Third slice Innermost, white, friable mass, close to 

 the healthy dentine; scraped out with a soft iron wire, and very 

 crumbly. Organic, 32.1 per cent., lime-salts, 67.9. This decay 

 shows therefore from the outside, a uniform advancement to the 

 normal composition of the tooth. It shows that the lime-salts are 

 removed, but not in any way which the acid theory demands. 

 * * * The tooth is disorganized, the soft, friable, white decay is 

 no longer organized, though chemically differing only slightly from 

 the tooth-substance." 



Now, if these experiments were conducted with the sole idea to 

 get at the truth, and from Prof. Mayr's standing as a chemist I hardly 

 think any one will doubt that, then I would respectfully ask in what 

 position the "acid theory" of caries is left? It would seem that, 

 to every fair, unprejudiced mind, it must share the same fate that 

 the " septic or germ theory " has at the hands of Dr. Miller. "With 

 these two theories so effectually disposed of, I will now present my 

 " theory," namely, the " acid inflammatory theory!" 



The more I study this subject the more I become convinced that 

 the first lesion under all circumstances is due to the action of an 

 acid, which, in a merely chemical way, dissolves out the lime-salts 

 from the enamel. The exact acid might be very difficult to deter- 

 mine, for the reason that so many kinds of food are taken into the 

 mouth which are acid themselves (such as the different kinds of 

 pickles, fruit, &c.), or, by fermentation, readily produce acids. This 

 acid need not be strong, for, as you are well aware, it is in many 

 cases years and years held in contact with the same spot npon the 

 tooth. Like the constant dropping of water that wears the stone, 

 the constant application of a very dilute acid will eventually dis- 

 solve the lime-salts from the most perfectly calcified enamel of a 

 tooth. Perhaps the sour decomposition is assisted locally by the 

 action of micrococci and leptothrix, although these organisms are 

 known to prosper only in alkaline, and not in acid fluids. These 

 vegetable organisms are present in innumerable quantities in the 

 healthiest gum; tartar is crowded with them; and even in the 

 highest degree of development of tartar caries is absent. In fact, 

 when decayed cavities in teeth become filled with tatar, the carious 

 process is as effectually stopped as it is possible for it to be when 

 filled in the most perfect manner with gold or other material. 



