Optical pH measurement system using a single fluorescent dye for assessing susceptibility to dental caries

• Published in: Journal of biomedical optics Vol. 24; no. 1; p. 1
• Main Authors: Sharma, Manuja, Graham, Jasmine Y., Walczak, Philip A., Nguyen, Ryan, Lee, Lauren K., Carson, Matthew D., Nelson, Leonard Y., Patel, Shwetak N., Xu, Zheng, Seibel, Eric J.
• Format: Journal Article
• Language: English
• Published: United States S P I E - International Society for 01.01.2019; Society of Photo-Optical Instrumentation Engineers
• Subjects: Acid production; Acids; Adult; Algorithms; Bacteria; Biofilms; Buffers; Calibration; Demineralization; Demineralizing; Dental caries; Dental Caries - diagnostic imaging; Dental enamel; Dental Enamel - diagnostic imaging; Dental hygiene; Dental plaque; Dental Plaque - diagnostic imaging; Dyes; Excitation; Excitation spectra; Female; Fiber optics; Fluorescent dyes; Fluorescent Dyes - chemistry; Fluorescent indicators; Human performance; Humans; Hydrogen-Ion Concentration; Hygiene; In vivo methods and tests; Light; Male; Optics and Photonics; Oral Hygiene; pH effects; Photobleaching; Pilot Projects; Sensing; Spectrometry, Fluorescence - instrumentation; Spectrometry, Fluorescence - methods; Sucrose; Sucrose - chemistry; Teeth; Time dependence; Time measurement; Tooth Demineralization; Young Adult; dianion; fluorescein; anion; plaque; fluorescence; pH; unmixing; caries
• ISSN: 1083-3668; 1560-2281; 1560-2281
• DOI: 10.1117/1.JBO.24.1.017001

Sugar-rich diets and poor dental hygiene promote the formation of a biofilm (plaque) that strongly adheres to the dental enamel surface and fosters the evolution of aciduric bacteria. The acid contributes to demineralization of the exterior tooth enamel, which accelerates after the pH drops below a critical value (∼5.5) for extended time periods resulting in the need for restorative procedures. Preventative techniques to alert the dentist and caries-susceptible patients regarding vulnerability to dental decay require a clinical measure of plaque activity. Therefore, there is a need to evaluate the acid production capability of plaque deposits in the pits and fissures of occlusal and interproximal regions. A ratiometric fluorescence pH-sensing device has been developed using an FDA-approved dye and LED excitation. Fluorescein spectral profiles were collected using a spectrometer and analyzed with a spectral unmixing algorithm for calibration over the pH range of 4.5 to 7. An in vivo pilot study on human subjects was performed using a sucrose rinse to accelerate bacterial metabolism and to measure the time-dependent drop in pH. The optical system is relatively immune to confounding factors such as photobleaching, dye concentration, and variation in excitation intensity associated with earlier dye-based pH measurement techniques.