Red fluorescence of dental biofilm as an indicator for assessing the efficacy of antimicrobials

Eun Song Lee, Elbert De Josselin De Jong, Hoi In Jung, Baek Il Kim

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14 Citations (Scopus)


The study aimed to determine whether the red fluorescence (RF) of a dental microcosm biofilm as measured with quantitative light-induced fluorescence (QLF) technology is useful for assessing the efficacy of antimicrobials. Dental microcosm biofilms were formed on bovine enamel discs and grown under 0.3% sucrose challenge and treated with chlorhexidine (CHX) solutions at different concentrations (0.05%, 0.1%, and 0.5%) plus a negative control [sterile distilled water (DW)] twice daily for 7 days. The biofilms were photographed using a QLF-digital system to evaluate the RF by calculating the red/green ratio, and pH values of the medium were measured daily. After 7 days, the bacterial viability of the biofilm was assessed by measuring the counts of viable total bacteria and aciduric bacteria, and the percentage surface microhardness changes (%SHC) was evaluated. The RF and cariogenic properties were compared for the different concentrations of CHX, and their correlations were examined. The RF and its increase rate were much lower for CHX-treated biofilms than for DW-treated biofilms. The RF after 7 days of maturation decreased significantly with increasing CHX concentrations (p<0.001) and was from 31% (for 0.05% CHX) to 46% (for 0.5% CHX) lower than that of the DW group. Strong correlations were reported between the RF of the 7-day-maturation biofilms and cariogenic properties, such as the number of total bacteria (r=0.93), number of aciduric bacteria (r=0.97), supernatant pH (r=0.43), and %SHC (r=0.98). In conclusion, the RF of dental biofilms as measured with QLF technology can be used to nondestructively assess and monitor the effect of antimicrobials against biofilm.

Original languageEnglish
Article number015003
JournalJournal of Biomedical Optics
Issue number1
Publication statusPublished - 2018 Jan

Bibliographical note

Funding Information:
Inspektor Research Systems BV provided the salary for author Elbert de Josselin de Jong (EdJdJ) but did not have any additional role in the study design, data collection, analysis, decision to publish, or preparation of the paper. EdJdJ’s involvement in this research was under the auspices of his status as adjunct professor at Yonsei University College of Dentistry supported by Brain Pool Program and BK21 PLUS Project. The specific role of EdJdJ was to provide for his expertise regarding the fluorescence technology. This does not alter the author’s adherence to the Journal of Biomedical Optics policies on sharing data and materials. EdJdJ holds several patents with respect to QLF technology. The remaining authors declared no conflicts of interest.

Funding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education under grant (No. 2016R1D1A1A09916934) and the Brain Pool Program through the Korean Federation of Science and Technology Societies (KOFST) funded by the Korean Government (Ministry of Science, ICT and Future Planning).

Publisher Copyright:
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE).

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering


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