Photoacoustic microscopy (PAM) utilizes short laser pulses to deposit energy into light
absorbers and sensitively detects the ultrasonic waves the absorbers generate in response.
PAM directly renders a three-dimensional spatial distribution of sub-surface optical absorbers.
Unlike other optical imaging technologies, PAM features label-free optical absorption contrast
and excellent imaging depths. Standard dental imaging instruments are limited to X-ray and
CCD cameras. Subsurface optical dental imaging is difficult due to the highly-scattering enamel
and dentin tissue. Thus, very few imaging methods can detect dental decay or diagnose dental
pulp, which is the innermost part of the tooth, containing the nerves, blood vessels, and other
cells. Here, we conducted a feasibility study on imaging dental decay and dental pulp with PAM.
Our results showed that PAM is sensitive to the color change associated with dental decay.
Although the relative PA signal distribution may be affected by surface contours and subsurface
reflections from deeper dental tissue, monitoring changes in the PA signals (at the same site)
over time is necessary to identify the progress of dental decay. Our results also showed that
deep-imaging, near-infrared (NIR) PAM can sensitively image blood in the dental pulp of an in
vitro tooth. In conclusion, PAM is a promising tool for imaging both dental decay and dental