Abstract:Introduction
Several studies suggest that near-IR imaging methods at wavelengths longer than 1,300nm have great potential for caries detection. In this study, the diagnostic performance of both near-IR transillumination and near-IR reflectance was assessed on teeth scheduled for extraction due to orthodontic treatment (n = 109 teeth on 40 test subjects).
Methods
Three intra-oral near-IR imaging probes were fabricated for the acquisition of in vivo images using a high definition InGaAs camera and near-IR broa… Show more
“…Several studies have indicated that light scattering of a tooth enamel surface notably decreases from the visible spectrum to the near‐infrared (NIR), and that wavelengths of 1300−1700 nm have great potential for detecting caries and other diseases . Studies have shown that the NIR illumination (NIRi) method can produce contrast that is sufficient for interproximal/occlusal carious lesion imaging . However, there are several major limitations of the NIRi method.…”
Indocyanine green (ICG) has been widely used in medical imaging, such as in retinal angiography. Here, we describe a pilot ex vivo study of ICG‐assisted near‐infrared fluorescence (NIRF) dental imaging in the first (700–950 nm for ICG‐NIRF‐I) and second (1000–1700 nm for ICG‐NIRF‐II) NIR windows using human extracted teeth; our study is compared with the traditional prevalent X‐ray imaging and NIR II illumination (NIRi‐II, 1310 nm) without ICG enhancement. The results show that ICG fluorescence has much better imaging contrast in both windows compared with NIRi‐II (by quantitatively comparing NIR intensity of the critical neighboring structures, such as enamel and dentin). Cracked teeth, notoriously hard to diagnose by dental X‐ray and computed tomography, were clearly profiled in NIRF dental imaging. An insidious occlusal caries, missing in X‐ray imaging, became a bright dot that was readily observed in ICG‐NIRF‐I images. For dental decay, NIRF imaging with ICG enhancement could clearly delineate the decay boundary. NIRF in both windows distinguished interproximal and occlusal superficial caries. Overall, ICG‐assisted NIRF dental imaging has unique advantages in identifying cracked teeth and insidious caries. The two NIR imaging windows used in our study might one day serve as noninvasive and nonionizing‐radiation methods for the diagnosis of critical dental diseases in situ.
“…Several studies have indicated that light scattering of a tooth enamel surface notably decreases from the visible spectrum to the near‐infrared (NIR), and that wavelengths of 1300−1700 nm have great potential for detecting caries and other diseases . Studies have shown that the NIR illumination (NIRi) method can produce contrast that is sufficient for interproximal/occlusal carious lesion imaging . However, there are several major limitations of the NIRi method.…”
Indocyanine green (ICG) has been widely used in medical imaging, such as in retinal angiography. Here, we describe a pilot ex vivo study of ICG‐assisted near‐infrared fluorescence (NIRF) dental imaging in the first (700–950 nm for ICG‐NIRF‐I) and second (1000–1700 nm for ICG‐NIRF‐II) NIR windows using human extracted teeth; our study is compared with the traditional prevalent X‐ray imaging and NIR II illumination (NIRi‐II, 1310 nm) without ICG enhancement. The results show that ICG fluorescence has much better imaging contrast in both windows compared with NIRi‐II (by quantitatively comparing NIR intensity of the critical neighboring structures, such as enamel and dentin). Cracked teeth, notoriously hard to diagnose by dental X‐ray and computed tomography, were clearly profiled in NIRF dental imaging. An insidious occlusal caries, missing in X‐ray imaging, became a bright dot that was readily observed in ICG‐NIRF‐I images. For dental decay, NIRF imaging with ICG enhancement could clearly delineate the decay boundary. NIRF in both windows distinguished interproximal and occlusal superficial caries. Overall, ICG‐assisted NIRF dental imaging has unique advantages in identifying cracked teeth and insidious caries. The two NIR imaging windows used in our study might one day serve as noninvasive and nonionizing‐radiation methods for the diagnosis of critical dental diseases in situ.
“…Recent studies have demonstrated that in addition to being able to acquire high contrast images of occlusal demineralization with extremely high contrast [1, 2], interproximal lesions well below the surface can be imaged in vivo [3]. Therefore, NIR imaging can be potentially used to guide lasers for the removal of lesions on tooth proximal surfaces.…”
Recent studies have shown that near-IR (NIR) imaging methods such as NIR reflectance can be used to image lesions on proximal surfaces, and optical coherence tomography (OCT) can be used to measure the depth of those lesions below the tooth surface. These imaging modalities can be used to acquire high contrast images of demineralized tooth surfaces, and 2-D and 3-D images can be extracted from this data. At NIR wavelengths longer than 1200-nm, there is no interference from stains and the contrast is only due to the increased light scattering of the demineralization. Previous studies have shown that image-guided laser ablation can be used to remove occlusal lesions, but its use for the removal of subsurface lesions on proximal surfaces has not been investigated. The objective of this study is to demonstrate that simultaneously scanned NIR and CO 2 lasers can be used to selectively remove natural and artificial interproximal caries lesions with minimal damage to sound tooth structure. In this study, images of simulated and natural interproximal lesions on extracted teeth were imaged using a digital microscope, a scanned 1460-nm superluminescent laser diode with an InGaAs detector and a cross polarization OCT system operating at 1300-nm. The lesions were subsequently removed with a CO 2 laser operating at 9.3-µm and the dental handpiece and the volume of sound tissue removed was compared.
“…At 1310 nm, mild fluorosis and other shallow defects may be discernable depending on their severity, geometry, and method of imaging [22]; Hirasuna et al suggest multimodal NIR imaging as a potential means for differentiating between mild fluorosis and deeper caries. Taken altogether, NIR dental imaging has produced condition-dependent applications that challenge or exceed two-dimensional radiographs without the use of ionizing radiation, and work has been done to compare the diagnostic capabilities of both technologies [15], [19], [23]. FIGURE 1.Common NIR imaging modes.…”
2-D radiographs, while commonly used for evaluating sub-surface hard structures of teeth, have low sensitivity for early caries lesions, particularly those on tooth occlusal surfaces. Radiographs are also frequently refused by patients over safety concerns. Translucency of teeth in the near-infrared (NIR) range offers a non-ionizing and safe approach to detect dental caries. We report the construction of an NIR (850 nm) LED imaging system, comprised of an NIR source and an intraoral camera for rapid dental evaluations. The NIR system was used to image teeth of ten consenting human subjects and successfully detected secondary, amalgam–occluded and early caries lesions without supplementary image processing. The camera-wand system was also capable of revealing demineralized areas, deep and superficial cracks, and other clinical features of teeth usually visualized by X-rays. The NIR system’s clinical utility, simplistic design, low cost, and user friendliness make it an effective dental caries screening technology in conjunction or in place of radiographs.
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