PRATIK SHAH

Three-dimensional radiographs are commonly used for evaluating sub-surface hard structures of teeth, but they have low sensitivity for early caries lesions, particularly those on tooth occlusal surfaces, and they are also frequently refused by patients over safety concerns. Cone beam computed tomography (CBCT) is also widely used for 3D diagnosis but is expensive and relatively cumbersome. Near-infrared imaging (NIR) offers a non-ionizing alternative for 3D dental analysis. We examine and compare features in multiple extracted teeth using conventional radiographic, CBCT, and NIR transillumination imaging modes. NIR imaging can provide unique diagnostic value, primarily in its ability to reveal the extent of surface demineralization. We also provide examples where NIR illumination indicated underlying problem sites in need of further clinical attention and propose the use of NIR imaging to guide targeted and rational use of ionizing radiation in patients.

Why is this work important?

Three and two-dimensional radiographs and cone beam computed tomography are commonly used for evaluating sub-surface hard structures of teeth. While radiographs are the current standard of care for diagnostic dental imaging, they have low sensitivity for early caries lesions, particularly those on tooth occlusal surfaces. They are also frequently refused by patients over safety concerns about exposure to ionizing radiation. Medical image acquisition without ionizing radiation can expand the use of important diagnostic tools and decrease safety concerns.

What has been done before?

NIR light can be transmitted across healthy dental enamel with marginal scattering, allowing for imaging dental features. Much previous work has focused on light at 1310 nm, which strikes a balance between enamel and water attenuation, but such a wavelength often requires expensive sensors to image. NIR light at 850 nm has similar dental imaging properties, but it has not been studied as thoroughly as NIR at 1310 nm. It is not well understood what clinical features, if any, are present in NIR dental images, especially at 850 nm. Our previous work has examined the sensitivity of 850 nm NIR images to early caries lesions, but if NIR is to synergistically augment 2D X- Rays and CBCT as the standard of care, we must evaluate how well such images represent other clinical features.

What are our contributions?

We examine and compare features in multiple extracted teeth using conventional radiographic, CBCT, and NIR transillumination modes. NIR imaging can provide unique diagnostic value, primarily in its ability to reveal the extent of surface demineralization. We also provide examples where NIR illumination indicated underlying problem sites in need of further clinical attention and propose the use of NIR imaging to guide targeted and rational use of ionizing radiation in patients. We also show that NIR imaging identifies clinical features associated with early dimineralization and enamel caries that are not apparent upon expert visual examination.

What are the next steps?

Model the interaction and scattering of light inside the tooth and tissues in order to provide even more diagnostic power.