The effects of surgical exposures of dental pulps in germfree and conventional laboratory rats.

T hc problem of maintaining thr vitality of a clinically exposed dental pulp by various conservative procedures to encourage the development of dentinal bridging has been the subject of numerous investigations.‘--’ The unpredictability of rrsults obtained from these procedures, however, ha.s been the source of great consternation to most operati\c clinicians. In those instances of successful management of pulpal exposures, a, considerable part of the success has been attributed to the extraordinary dcgrec of pulpal tissue resistance.: Reasons gi\-cn for the failure in formation of a hard-t,issue pulpal seal have included a.ge of the patient, degree of surgical trauma, excessive sealing pressures, improper choice of medication, bacterial infection, and a low threshold of host resistance. l3ecauscl of the frequency of adverse results obtained after the pulp-capping treatment of acute or chronically infected dental pulps, regardless of all the other conditions present, these particular cases arc no longer considered for this type of procedure. The microorganisms in these acute and chronically inflamed pulpal cxposurcs have therefore been thought to be the most significant cause of failures in attempts at dentinal bridging. To t,est conclusively the influence of riablc microorganisms on the fate of a surgically exposed dental pulp, a study utilizing germ-free animals was undertaken.