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Fluorescein based optical detection of oral pH (Conference Presentation)
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Paper Abstract

We have developed a new tool to measure the acid production by plaque oral bacteria. Many species of oral bacteria metabolize sugars in food and produce organic acids that demineralize the dental enamel leading to the formation of cavities. Measuring the acidity level before and after a sugar rinse can indicate the susceptibility of an individual to tooth decay and location of active caries. In a case study on two subjects, a non-contact optics-based pH device was able to track pH before and after a sugar rinse. The fiber optic probe measures acidity level in difficult to access dental locations such as occlusal pits and fissures based on changes in the spectral fluorescence profile of fluorescein (FL) dye. Fiber coupled 420 nm LED excites 200uM aqueous FL solution in the mouth. The fluorescence spectrum in 450-650 nm range is obtained using an adjacent fiber optic cable coupled to a spectrometer. Chemometric analysis of endmember dianion and anion species using least-square fitting is performed to determine the pH of the FL absorbed into the extracellular region of the oral biofilm. Other unwanted noise, like background light and auto-fluorescence in the range of 450-650 nm is removed before calculating biofilm pH. Using this device in a darkened room on two subjects, we were able to measure resting pH (before a sugar rinse) and track time dependent change in pH (after a sugar rinse) in the range of pH 4-7 paving the way for first clinical optical pH measurement in the mouth.

Paper Details

Date Published: 7 March 2019
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Proc. SPIE 10857, Lasers in Dentistry XXV, 108570B (7 March 2019); doi: 10.1117/12.2511219
Show Author Affiliations
Manuja Sharma, Univ. of Washington (United States)
Jasmine Y. Graham, Univ. of Washington (United States)
Philip A. Walczak, Univ. of Washington (United States)
Ryan M. Nguyen, Univ. of Washington (United States)
Lauren K. Lee, Univ. of Washington (United States)
Matthew D. Carson, Univ. of Washington (United States)
Alireza Sadr, University of Washington (United States)
Zheng Xu, Univ. of Washington (United States)
Len Y. Nelson, Univ. of Washington (United States)
Shwetak Patel, Univ. of Washington (United States)
Eric J. Seibel, Univ. of Washington (United States)


Published in SPIE Proceedings Vol. 10857:
Lasers in Dentistry XXV
Peter Rechmann; Daniel Fried, Editor(s)

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