Characterization of dental caries using Optical Coherence Tomography

Abstract

BackgroundOptical Coherence Tomography (OCT) is a noninvasive imaging technique that compiles successive interferometric signals into a tomographic image. Although the capacity of OCT to image dental structures has been verified, the anisotropic nature of teeth and gingival tissue may limit the resolution of conventional OCT.ObjectiveThe objective of this study was to compare the imaging characteristics of dental caries using polarization-sensitive (ps-OCT) and conventional OCT.Study designFive teeth with no evidence of caries and 4 teeth with dentinal caries were imaged using 2 prototype OCT systems. The conventional OCT system consisted of an autocorrelator scanning interferometer using a 1310-nm (60 nm spectral bandwidth) 14-mW superluminescent diode (SLD) light source. The second system was a prototype ps-OCT using a 2-mW, 1300-nm SLD with a spectral bandwidth of 40 nm. Light from the SLD first passed a vertical polarizer and was then separated by a beamsplitter. In the sample arm, light was circularly polarized with a quarter waveplate in which the fast axis was oriented at 45 degrees with respect to the vertical direction. Light returning from both the sample and the reference arms was again separated by a polarizing beamsplitter. The vertically and horizontally polarized signals were then detected in 2 channels and images were reconstructed by combining the signals.ResultsConclusionsOur ps-OCT dental prototype provides higher-resolution images and should introduce a precision of measurement that is not possible with current methods. Ps-OCT is relatively inexpensive, is noninvasive, and can produce 3-dimensional images of dental caries. BackgroundOptical Coherence Tomography (OCT) is a noninvasive imaging technique that compiles successive interferometric signals into a tomographic image. Although the capacity of OCT to image dental structures has been verified, the anisotropic nature of teeth and gingival tissue may limit the resolution of conventional OCT. Optical Coherence Tomography (OCT) is a noninvasive imaging technique that compiles successive interferometric signals into a tomographic image. Although the capacity of OCT to image dental structures has been verified, the anisotropic nature of teeth and gingival tissue may limit the resolution of conventional OCT. ObjectiveThe objective of this study was to compare the imaging characteristics of dental caries using polarization-sensitive (ps-OCT) and conventional OCT. The objective of this study was to compare the imaging characteristics of dental caries using polarization-sensitive (ps-OCT) and conventional OCT. Study designFive teeth with no evidence of caries and 4 teeth with dentinal caries were imaged using 2 prototype OCT systems. The conventional OCT system consisted of an autocorrelator scanning interferometer using a 1310-nm (60 nm spectral bandwidth) 14-mW superluminescent diode (SLD) light source. The second system was a prototype ps-OCT using a 2-mW, 1300-nm SLD with a spectral bandwidth of 40 nm. Light from the SLD first passed a vertical polarizer and was then separated by a beamsplitter. In the sample arm, light was circularly polarized with a quarter waveplate in which the fast axis was oriented at 45 degrees with respect to the vertical direction. Light returning from both the sample and the reference arms was again separated by a polarizing beamsplitter. The vertically and horizontally polarized signals were then detected in 2 channels and images were reconstructed by combining the signals. Five teeth with no evidence of caries and 4 teeth with dentinal caries were imaged using 2 prototype OCT systems. The conventional OCT system consisted of an autocorrelator scanning interferometer using a 1310-nm (60 nm spectral bandwidth) 14-mW superluminescent diode (SLD) light source. The second system was a prototype ps-OCT using a 2-mW, 1300-nm SLD with a spectral bandwidth of 40 nm. Light from the SLD first passed a vertical polarizer and was then separated by a beamsplitter. In the sample arm, light was circularly polarized with a quarter waveplate in which the fast axis was oriented at 45 degrees with respect to the vertical direction. Light returning from both the sample and the reference arms was again separated by a polarizing beamsplitter. The vertically and horizontally polarized signals were then detected in 2 channels and images were reconstructed by combining the signals. Results ConclusionsOur ps-OCT dental prototype provides higher-resolution images and should introduce a precision of measurement that is not possible with current methods. Ps-OCT is relatively inexpensive, is noninvasive, and can produce 3-dimensional images of dental caries. Our ps-OCT dental prototype provides higher-resolution images and should introduce a precision of measurement that is not possible with current methods. Ps-OCT is relatively inexpensive, is noninvasive, and can produce 3-dimensional images of dental caries.