Thomas B. Hartzell

A Microscopic Study of Pulps from Infected Teeth

It is generally considered that so long as the pulp is protected by an intact wall of dentin, it is free from infection; that only when the pulp chamber becomes exposed by caries or trauma does the pulp tissue become invaded by microorganisms, and that then it usually undergoes suppuration or gangrenous inflammation; and that the pain which occurs previous to actual exposure of the pulp is due to hyperemia, caused either by temperature changes or by lactic acid absorbed through the dentinal tubules. This conception of the process of natural revitalization finds general expression in the text-books on dental pathology. We believe, on the contrary, that the pulp is frequently invaded by microorganisms long before it has been exposed by caries or, indeed, in the absence of caries, by organisms which have passed into the pulp from the gingival region; and that such invading organisms give rise in the pulp to localized areas of inflammation which are not necessarily suppurative or gangrenous in nature, but rather granulomatous and progressive, leading to fibrosis or other changes. When suppuration and gangrene finally occur, it is in a tissue which has