Methods: For many diagnostic purposes lateral flow devices are well known, e.g. for pregnancy tests. A similar technological approach was used for the development of ExplOra® CR, i.e. target specific monoclonal antibodies were developed, then conjugated to colloidal reddish gold and brownish silver, respectively, and transferred to the a lateral flow device. The conjugated antibodies are detecting Streptococcus mutans and Lactobacillus sp. in saliva samples when the chromatographic process has been started. During this process the complex from conjugated antibodies and bacterial cells is blotted onto a membrane where it is bound by further target specific antibodies. The more cariogenic bacteria are in the saliva the more complex is bound by the target antibodies and the more intensive is the colour at the test line. The intensity of the colour correlates with number of the microorganisms which was tested by the use of classical microbiological methods as well as ELISA and PCR.
Results: A caries risk test was developed that is very sensitive (at least 500 cfu per sample) and useful to count bacteria semi-quantitatively in four classes in accordance with at least three orders of magnitude of cfu/ml (3.70-6.70 given as log).
Conclusion: The device enables a quick assessment of the caries risk in less than 15 minutes. The semi-quantitatively assessed signal intensity allows the determination of different risk classes.