Bacteria in experimentally infected cavity preparations.

The presence of bacteria on cavity walls was assessed histologically following experimental infection by inserting soft carious human dentin or guttapercha temporary filings in 40 monkey teeth. Eighty-five infected cavities which had been restored using zinc oxide-eugenol cement (34 teeth), Ca(OH)2 (39 teeth) or amalgam (12 teeth) were also evaluated. Bacteria could regularly be demonstrated in cavities where soft carious human dentin had remained in the cavities for 82 d, but not, or only very rarely, in any of the other series. It was concluded that vital dentin has considerable resistance against infection and that cavity sterilization appears to be of questionable value.