Objective The high transparency of dental enamel in the near-IR (NIR) light at 1,310-nm can be exploited for imaging dental caries without the use of ionizing radiation (X-rays). We present the results of the first in vivo imaging study in which NIR images were acquired of approximal contact surfaces. Methods NIR imaging hand-pieces were developed and attached to a compact InGaAs focal plane array and subsequently used to acquire in vivo NIR images of 33 caries lesions on 18 test subjects. The carious lesions were discernible on bitewing radiographs, but were not visible upon clinical examination. Results NIR images were acquired in vivo from three directions and the majority of lesions examined were too small to require restoration, based on accepted bitewing radiograph criteria. All but one of the 33 lesions examined were successfully imaged from at least one direction. Conclusion This first in vivo study of imaging at the 1,310-nm wavelength region shows that NIR imaging has great potential as a screening tool for the detection of approximal lesions without the use of ionizing radiation.

Background and Objectives-The purpose of this study was to assess the potential of polarization sensitive optical coherence tomography (PS-OCT) to non-destructively measure the depth and severity of artificial demineralization on exposed root surfaces and measure the degree of inhibition by topical fluoride. Although PS-OCT imaging studies have demonstrated the utility of PS-OCT for imaging carious lesions on enamel and dentin surfaces the influence of the cementum layer that is present on intact root surfaces has not been investigated.Materials and Methods-In this study, extracted human tooth roots were partitioned into three sections with one partition treated with topical fluoride, one partition protected from demineralization with acid resistant varnish, and one partition exposed to a demineralization solution, producing artificial lesions approximately 200-µm deep in root dentin. The lesion depth, remaining cementum thickness and the integrated reflectivity for lesion areas was measured with PS-OCT. These measurements were also compared with more established methods of measuring demineralization, namely transverse microradiography (TMR) and polarized light microscopy (PLM)Results-PS-OCT was able to measure a significant increase in the reflectivity between lesion areas and sound root surfaces. In contrast to dentin, the cementum layer manifests minimal reflectivity in the PS-OCT images allowing nondestructive measurement of the remaining cementum thickness. The reflectivity of the cementum layer did not increase significantly after substantial demineralization, however it did manifest considerable shrinkage in a fashion similar to dentin and that shrinkage could be measured with OCT.Significance-This study demonstrates that PS-OCT can be used to measure demineralization nondestructively on root surfaces and assess inhibition of demineralization by anticaries agents.

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Introduction-The aims of this study were to test the hypothesis that Polarization SensitiveOptical Coherence Tomography (PS-OCT) can be used to nondestructively measure and quantify the severity of the early demineralization of enamel on buccal and occlusal surfaces and assess the inhibitory effect of fluoride varnish in vivo.

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