The opinions as to the cause and treatment of pyorrhea are as diverse at the present time as they were many years ago. The most common belief of the dentists is that the disease is a local process. The author, after careful ob servation covering a number of years, does not agree with this theory, but believes that the dis ease is the result of constitutional and exciting causes which lower the vital resistance of the alveolar process, gum, and the peridental mem brane. The body, in other words, is out of har mony physiologically, and as a result thereof, manifests itself in the alveolar process, the gum, and the peridental membrane.