A Smart Light Probe to Detect Early Tooth Decay Risk
Why Tooth Decay Remains a Global Challenge
Tooth decay, or dental caries, is the most common health problem worldwide, affecting more than 2 billion people. It begins when bacteria in dental plaque (the sticky biofilm on teeth) produce acid after consuming sugar. Over time, these acids weaken enamel, leading to cavities.
The problem? Dentists today mainly rely on visual inspection and X-rays to spot damage after it’s already done. What’s missing is a reliable, real-time tool to measure early signs of risk—before a cavity forms.
Meet O-pH: A Light-Based Dental Biofilm Monitor
Researchers from the University of Washington have developed O-pH, a handheld device that uses safe fluorescent dye (sodium fluorescein, already FDA-approved) to measure acidity directly inside dental plaque.
By shining blue light on the dye and analyzing the emitted glow, the device can estimate pH levels—a key indicator of cavity risk. In simple terms: the lower the pH, the more acidic and dangerous the plaque.
Clinical Testing in Children
The team tested O-pH on 30 children at high risk for cavities. They measured plaque pH before and after a sugar rinse (simulating what happens when we eat sweets).
Key findings:
Children without recent professional cleaning had lower baseline and post-sugar pH than those who had recently visited the dentist.
Acid levels dropped more sharply in children with heavy plaque buildup, confirming the device’s ability to distinguish between healthy and unhealthy oral environments.
In some cases, unhealthy tooth surfaces showed consistently more acidic readings than healthy ones.
From Point Measurements to Imaging
The first version of O-pH worked like a “point probe,” measuring pH spot by spot. To overcome this limitation, the researchers also adapted the technology into an imaging-based version using a scanning fiber endoscope. This prototype produced colorful pH heatmaps of the mouth, showing exactly where acids concentrate after sugar exposure.
Why This Matters
O-pH could represent a shift from reactive to proactive dentistry. Instead of waiting for cavities to appear, dentists could track plaque acidity over time and give patients personalized feedback. The tool could also help motivate children and young adults by visually showing the immediate effect of sugary diets on their teeth.
The researchers note that more studies are needed to confirm accuracy across larger populations, but the technology is a promising step toward early, non-invasive caries risk assessment.
Reference
Sharma, M., Lee, L. K., Carson, M. D., Park, D. S., An, S. W., Bovenkamp, M. G., Cayetano, J. J., Berude, I. A., Nelson, L. Y., Xu, Z., Sadr, A., Patel, S. N., & Seibel, E. J. (2022). O-pH: Optical pH Monitor to Measure Dental Biofilm Acidity and Assist in Enamel Health Monitoring. IEEE Transactions on Biomedical Engineering, 69(9), 2776–2787. https://doi.org/10.1109/TBME.2022.3153659