The Ability of Selected Oral Microorganisms to Emit Red Fluorescence

Abstract

Some novel caries detection and excavation devices rely on the ability of bacteria to produce red fluorescing compounds. The aim of this study was to examine the ability of selected oral microorganisms to emit red fluorescence. Streptococcus mutans, S. oralis, S. salivarius, S. sobrinus, Lactobacillus fermentans, L. casei, L. rhamnosus, Actinomyces naeslundi, A. israelii, Prevotella intermedia, and Fusobacterium nucleatum were inoculated onto Columbia agar with haemin and vitamin K and incubated anaerobically for up to 7 days in the dark. The resulting bacterial colonies were excited using filtered xenon light (405 ± 20 nm) and digitally photographed through a 530-nm high-pass filter. The red and green portions of the colony fluorescence were analyzed using a computer program and the red/green ratio was calculated. All colonies emitted both red and green fluorescence. The green outweighed the red portion for the following species (in descending order) S. oralis, S. salivarius, S. mutans, F. nucleatum and S. sobrinus. The red portion was higher for the following species (in descending order) P. intermedia, A. naeslundi, A. israelii, L. fermentans, L. rhamnosus and L. casei. With all the bacteria examined, one color portion generally outweighed the other, giving the visual impression of either red or green fluorescence. We conclude that red fluorescence is well suited to detection of the bacteria which cause dentin caries but it is not suitable as an indicator of the presence and activity of the streptococci involved in initial caries.

Is the red fluorescence of dental plaque related to its cariogenicity?

“…7 The first reports on this issue have focused on the red fluorescence produced by some anaerobic species of microorganisms cultured in the laboratory, such as some species of Actinomyces and microorganisms associated with periodontal disease. 3,11 Regarding dental caries, species of streptococci did not exhibit red fluorescence, 3,5,11 but various species of Lactobacilli emitted fluorescence at the red spectrum. 11 Recently, a research observed that microorganisms related to dental caries, including Streptococcus mutans, Lactobacillus salivarius, and Bifidobacterium dentium, produced red fluorescence when some nutrients were added to the growth media.…”

“…The authors observed that obligate anaerobic bacteria were the main source of red fluorescence, including microorganisms usually present in thicker plaque and in dentin caries lesions. 3,11 The subsequent studies investigated the red fluorescence emitted by the dental plaque, evaluating whether the interactions among the microorganisms could have some influence on it. It was observed that combinations of some bacterium were more associated with the emission of red fluorescence than the individual species of microorganisms, 6 and that this phenomenon is supposed to be related to the maturity of the dental plaque.…”

Quantified light-induced fluorescence, review of a diagnostic tool in prevention of oral disease

“…The absence of RF is also used as indicator when a cavity preparation is clean. 43,44 Current research on RF focuses mainly on bacteria that could be a source for this RF and bacteria interactions and growth conditions. 10,43,45,46 Recently a more clinical approach is found in research of RF in relation to gingivitis, where not the red or GF of the teeth is the object of study but the RF seen from the subgingival plaque growing under the gums.…”

On the red fluorescence emission of <i>Aggregatibacter actinomycetemcomitans</i>

“…Studies have suggested that obligate anaerobic bacteria are the source of red fluorescence emission and especially the black pigmented e.g. Prevotella intermedia and Porphyromonas gingivalis [3,5,6,8,9]. In addition the majority of these studies havealso suggested that the red fluorescence emission not is directly caused by a single bacterium species, but "by the intrinsic characteristics of a mature biofilm" [6][7][8][9].…”

“…Red fluorescence emission has been demonstrated from Actinomyces odontolyticus, Actinomyces naeslundi, Actinomyces israelii and Prevotella intermedia present in cell cultures associated with dental caries, periodontal disease and dental plaque [3,[5][6][7]. Red fluorescence has also been obtained from the black-pigmented obligate anaerobes Porphyromonas gingivalis, P. intermedia, Prevotella melaninogenica, as well as from A. israelii [8].…”