Early detection of dental caries using photoacoustics

K. Kim, R. S. Witte, I. Koh, S. Ashkenazi, M. O'Donnell

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


For decades, visual, tactile and radiographic examinations have been the standard for diagnosing caries. Nonetheless, the extent of variation in the diagnosis of dental caries is substantial among dental practitioners using these traditional techniques. Therefore, a more reliable standard for detecting incipient caries would be desirable. Using photoacoustics, near-infrared (NIR) optical contrast between sound and carious dental tissues can be relatively easily and accurately detected at ultrasound resolution. In this paper, a pulsed laser (Nd:YAG, Quanta-Ray) was used to probe extracted human molars at different disease stages determined from periapical radiographs. Both fundamental (1064nm) and first harmonic (532nm) pulses (15ns pulse length, 100mJ at fundamental and 9mJ at first harmonic, 10Hz pulse repetition rate) were used to illuminate the occlusal surface of tooth samples placed in a water tank. The photoacoustic signal was recorded with an unfocused wideband single-element piezoelectric transducer (centered at 12 MHz, bandwidth 15 MHz) positioned at small angle (less than 30 degrees) to the laser beam close to the occlusal surface. At the fundamental wavelength, total photoacoustic energy increases from normal to incipient stage disease by as much as a factor of 10. Differences between photoacoustic energy at the fundamental and first harmonic wavelength further indicate spectral absorption changes of the underlying structure with disease progression. Using a focused laser beam, an extracted molar with suspected incipient caries was scanned along the occulusal surface to help localize the caries inside enamel and dentin. The significantly increasing photoacoustic signal at a specific scan line both at fundamental and first harmonic indicates the local development of the incipient caries. The photoacoustic results compare well with visual inspection after layer by layer dissection. Preliminary results demonstrate the feasibility of detecting incipient occlusal and proximal caries. This technique may ultimately allow for continuous monitoring of caries before and during treatment.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2006
Event7th Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics - Photons Plus Ultrasound: Imaging and Sensing 2006 - San Jose, CA, United States
Duration: Jan 22 2006Jan 26 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


Other7th Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics - Photons Plus Ultrasound: Imaging and Sensing 2006
Country/TerritoryUnited States
CitySan Jose, CA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Early detection of dental caries using photoacoustics'. Together they form a unique fingerprint.

Cite this