Histologic changes in dental pulps of dogs and monkeys following application of pressure, drugs, and microorganisms on prepared cavities: Part II. Changes observable more than one month after Application of Traumatic Agents

Abstract

A progression of histologic changes was observed in the dental pulps of dogs and monkeys after various irritants had been applied to prepared cavities in the teeth. The changes occurring up to one month after treatment have been reported previously. 1 Three months after operation, the pulps had recovered from the trauma of simple cavity preparation. However, as judged by the quantity and structure of reparative dentine and by the presence of cells indicative of inflammation, pulps had not yet completely recovered from the additional trauma caused by the exertion of pressure or the application of silver nitrate or phenol to the cavities. Damage was particularly severe if the cavity was deep or if a combination of irritants had been applied. Damage was less severe if the cavity had been prepared with a drill rotating at a higher speed (50,000 r.p.m.). Six months after operation, pulps had largely recovered from the effects of pressure or of silver nitrate on shallow cavities. If phenol or a combination of irritants had been used, or if the cavities were deep, inflammation persisted. Test bacteria applied to the base of a cavity could penetrate the tubules and reach the deep pulp. Six months later, however, presumably because of the body's natural defenses, no bacteria were present in the pulp. The bacteria caused little or no damage; they were not nearly so harmful as the drugs commonly used for sterilization of the dentine.