Periapical destructions caused by experimental pulpal inoculation of Streptococcus mutans in rats

The development of pulpal and periapical changes in rat molars was studied after inoculation of Streptococcus mutans (GS-5) into the pulp chamber. Before injection into the pulp Streptococcus mutans was cultured on a special collagen substrate and "trained" to break down collagen. The destruction of the alveolar bone periapically could be demonstrated both roentgenologically and histopathologically. Large numbers of inflammatory cells in the pulp chamber and the periapical area, as well as carious dentin, were present. The pulpally inoculated bacteria could also be recovered from the systemic blood. The identity between the pulpally inoculated bacteria and the bacteria recovered from the blood was proved by gel precipitation.