Characterization of Dental Caries Using Optical Coherence Tomography

Objectives: Optical Coherence Tomography (OCT) is a non-invasive imaging technique that compiles successive interferometric signals into a tomographic image. The objective of this study was to compare the imaging characteristics of normal, carious and acid demineralized dentin using OCT. Methods: A prototype OCT system that consisted of an auto-correlator scanning interferometer using a 1310 nm (40 nm spectral bandwidth) 20 mW superluminescent diode (SLD) light source was used in this study. Images were scanned in a mesial to distal orientation. The total scan length was 12 mm, with a calculated axial resolution of 21 microns and an approximately 50 micron slice thickness. The total scan time was 30 seconds. Five teeth with no evidence of caries and 4 teeth with dentinal caries were imaged. The noncarious teeth were subsequently treated a 30 second application of 37% phosphoric acid gel and imaged again. Results: The OCT image characteristics of natural caries revealed its dynamic nature and was characterized by regions of demineralization (low signal intensity) and regions of remineralization (high signal intensity) resulting in an overall mottled appearance of the lesion. Unaffected dentin revealed a homogeneous pattern of intermediate signal intensity, while demineralized dentin was characterized by a sharply demarcated region of lower signal intensity. Conclusions: The results of this study indicate OCT provides high resolution images of dental caries that have greater structural detail than currently available imaging methods. OCT is relatively inexpensive, non-invasive and can produce three-dimensional images of dental caries.

Supported by NIDCR RO1-DE11154-10