Subtraction radiography of dentinal caries-like lesions induced in vitro by cariogenic bacteria.

PURPOSE The objective of this project was to develop an in vitro model system for investigations of dentinal caries. METHODS Five extracted primary molar teeth with circular cavity preparations to the depth of the dentinoenamel junction were mounted individually in cold-cure acrylic bases constructed to fit a positioning jig in a Schick-Technologies digital radiographic imaging apparatus. The mounted teeth (MT) were incubated with pure cultures of Streptococcus mutans for 7 days and Lactobacillus casei for 38 days. At baseline and on day 23 and 45, four digital radiographs of each MT were made. Subtraction radiography was performed and analyzed using custom interactive software. RESULTS Lesions progressed roughly halfway through the dentin in all teeth at 23 days and approximated the pulp chambers at 45 days of incubation. Images resulting from subtraction procedures clearly revealed incremental caries progression which could be quantitated. CONCLUSION The model may be useful for screening cariostatic dental materials or treatments and investigating microbial mechanisms in dentinal caries.