What does DIAGNOdent measure?

OBJECTIVES: The aim of this study was to investigate the auto-fluorescence response of the normal, cultivable, caries-associated bacterial flora and demineralized tooth tissue as measured with DIAGNOdent. MATERIAL AND METHODS: Bacteria: Lactobacilli, Streptococcus mutans and Actinomyces sp were cultivated on selective and non-selective media and measured with DIAGNOdent, directly on agar plates and on glass slides. S.mutans cultivated on mitis-salivarius-bacitracin agar (MSB) was measured with DIAGNOdent at different maturation levels. Teeth: 30 extracted premolar teeth, visually sound, were demineralized using three kinds of acids and measured with DIAGNOdent prior and after demineralization. RESULTS: Bacteria: Lactobacilli and Actinomyces showed no response to the laser light while S.mutans on MSB responded strongly. S.mutans responded only moderately when transported to glass slides and not at all when cultivated on bood agar. There was significant correlation between DIAGNOdent readings and mature cultures of S.mutans. Teeth: The effect of acid demineralization of enamel on DIAGNOdent readings were of no clinical interest, varying only from 0 to 3 in all cases. CONCLUSION: Demineralization with acid does not affect DIAGNOdent measurements. Bacterial products are more likely to be responsible for the increase in auto-fluorescence than the bactera themselves. The response is, however, very dependent on the bacterial species. The present study does not, therefore, lend support to the view that the DIAGNOdent device can be used to detect or monitor levels of infection or tissue demineralization during caries development.

Aknowledgement: This project was supported by the Icelandic Research Fund for Graduate Students and the Swedish Patent Revenue Fund for Research in Preventive Dentistry