Detection of carious lesions utilizing depolarization imaging by polarization sensitive optical coherence tomography.

Christian Hannig,Edmund Koch,Florian Tetschke,Franz Hempel,Jonas Golde,Julia Walther,Tobias Rosenauer

doi:10.1117/1.jbo.23.7.071203

Christian Hannig, Edmund Koch + Show 5 more

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https://doi.org/10.1117/1.jbo.23.7.071203

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Abstract

As dental caries is one of the most common diseases, the early and noninvasive detection of carious lesions plays an important role in public health care. Optical coherence tomography (OCT) with its ability of depth-resolved, high-resolution, noninvasive, fast imaging has been previously recognized as a promising tool in dentistry. Additionally, polarization sensitive imaging provides quantitative measures on the birefringent tissue properties and can be utilized for imaging dental tissue, especially enamel and dentin. By imaging three exemplary tooth samples ex vivo with proximal white spot, brown spot, and cavity, we show that the combination of polarization sensitive OCT and the degree of polarization uniformity (DOPU) algorithm is a promising approach for the detection of proximal carious lesions due to the depolarization contrast of demineralized tissue. Furthermore, we investigate different sizes of the DOPU evaluation kernel on the resulting contrast and conclude a suitable value for this application. We propose that DOPU provides an easy to interpret image representation and appropriate contrast for possible future screening applications in early caries diagnostics.

Highlights

The early identification of proximal carious lesions is still one of the most challenging issues in modern cariology and odontology, whereas several visual, optical, and radiographic techniques have been developed and improved in recent years.[1,2] Providing depthresolved, high-resolution images of biological samples, optical coherence tomography (OCT) is a promising tool for detecting caries noninvasively, since first investigations of dental hard tissue in vitro and in vivo were performed by OCT,[3,4] and imaging in the near-infrared range proved convenient scattering and absorption properties.[5]
To demonstrate the capability of the polarization sensitive OCT (PS-OCT) system for measuring birefringence in dental hard tissue and likewise comparing the effect of an early carious lesion on the different representation modalities, Fig. 2 shows the intensities measured by co- and cross-polarization channels as well as the resulting reflectivity
Less birefringence related to its substructure[26] and a decreased degree of polarization uniformity (DOPU), which has been previously observed[28] and occurs due to multiple scattering,[29] allow a delimitation from the surrounding enamel, as well as the in the intensity images visible dentin–enamel junction (DEJ)

Summary

Introduction

The early identification of proximal carious lesions is still one of the most challenging issues in modern cariology and odontology, whereas several visual, optical, and radiographic techniques have been developed and improved in recent years.[1,2] Providing depthresolved, high-resolution images of biological samples, optical coherence tomography (OCT) is a promising tool for detecting caries noninvasively, since first investigations of dental hard tissue in vitro and in vivo were performed by OCT,[3,4] and imaging in the near-infrared range proved convenient scattering and absorption properties.[5]. This includes polarization sensitive imaging and the consequent measurement of depthresolved birefringence, which until now has been applied in many biomedical as well as nonmedical fields.[8,9] In terms of hard dental tissue and caries detection, first polarization sensitive OCT (PS-OCT) measurements confirmed the birefringent properties of enamel and dentin,[4,10] and it was determined that

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