Clinical assessment of early tooth demineralization using polarization sensitive optical coherence tomography.

INTRODUCTION: The aims of this study were to test the hypothesis that polarization sensitive-optical coherence tomography (PS-OCT) can be used to non-destructively 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. METHODS: A split mouth design was used to assess the effects of fluoride varnish on inhibiting dissolution on 20 test subjects. Orthodontic bands with a buccal window were cemented on the premolars and small incisions were produced on occlusal surfaces to serve as sites for plaque retention for enhanced demineralization. Bands were removed after 30 days and PS-OCT scans were acquired in vivo of occlusal and buccal areas. Teeth were extracted, sectioned, and analyzed using polarized light microscopy (PLM) and transverse microradiography (TMR) for comparison with the PS-OCT images. RESULTS: High contrast PS-OCT images were acquired of both occlusal and buccal surfaces in vivo. Both occlusal and buccal surfaces, showed a significant difference (P < 0.05) in the integrated reflectivity (ΔR) between the "sound" and "carious" enamel groups. Although the mineral loss (ΔZ) and ΔR measured using TMR and PS-OCT were less for the fluoride varnish-treated buccal surfaces the difference was not statistically significant (P > 0.05). CONCLUSIONS: Our results indicate that PS-OCT can non-destructively measure early enamel demineralization on the buccal and occulsal surfaces in vivo.

Polarization-sensitive optical coherence tomography for the nondestructive assessment of the remineralization of dentin.

Previous studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can be used to image caries lesions in dentin, measure nondestructively the severity of dentin demineralization, and determine the efficacy of intervention with anticaries agents including fluoride and lasers. The objective of this study is to determine if PS-OCT can be used to nondestructively measure a reduction in the reflectivity of dentin lesions after exposure to a remineralization solution. Although studies have shown the ability of PS-OCT to image the remineralization of lesions in enamel, none have included dentin. PS-OCT images of dentin surfaces are acquired after exposure to an artificial demineralizing solution for six days and a remineralizing solution for 20 days. The integrated reflectivity, depth of demineralization, and thickness of the layer of remineralization are calculated for each of the two treatment groups on each sample. Polarized light microscopy and microradiography are used to measure lesion severity on histological thin sections for comparison. PS-OCT successfully measured the formation of a layer of increased mineral content near the lesion surface. Polorized light microscopy (PLM) and transverse microradiography (TMR) corroborated those results. PS-OCT can be used for the nondestructive measurement of the remineralization of dentin.

Nondestructive assessment of dentin demineralization using polarization-sensitive optical coherence tomography after exposure to fluoride and laser irradiation.

Previous studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can be used to image natural and artificial caries in dentin. The purpose of this study was to measure nondestructively the severity of artificial caries lesions in dentin and determine the efficacy of intervention with anticaries agents including fluoride and lasers. Although several studies have assessed the utility of PS-OCT to image caries lesions in enamel and to quantify the lesion severity, only a few studies have focused on lesions in dentin. In this study, images of artificial dentin lesions on extracted human teeth were acquired with PS-OCT. Before exposure to an artificial demineralizing solution, three incisions were made on the sample surfaces using either Er:YAG, Nd:YAG (lambda = 355 nm), or TEA CO(2) lasers and selected areas were treated with topical fluoride to create six unique treatment areas for each of the three laser conditions investigated. The integrated reflectivity and depth of demineralization were calculated for each of the six areas on each sample using the PS-OCT images. Polarized light microscopy (PLM) and transverse microradiography (TMR) were used to measure lesion severity on histological thin sections for comparison. PS-OCT successfully measured the inhibition of demineralization by topical fluoride. Laser irradiation was not particularly effective in increasing or decreasing the rate of dentin demineralization. PLM and TMR corroborated those results. This study demonstrates that PS-OCT can be used to measure demineralization on dentin surfaces and determine the degree of inhibition of demineralization by anticaries agents.

Assessment of Dentin Remineralization with PS-OCT.

Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to image natural root caries lesions, measure non-destructively the severity of dentin demineralization and determine the efficacy of intervention with anti-caries agents including fluoride and lasers. The objective of this study was to determine if PS-OCT could be used to nondestructively measure the formation of a layer of remineralized dentin on the surface of dentin lesions after exposure to a remineralization solution. In this study images of artificial dentin lesions on extracted human teeth were acquired using PS-OCT after exposure to an artificial demineralizing solution at pH 4.9 for six days and after subsequent exposure to a remineralizing solution at pH 7.0 for 20 days. Polarized light microscopy and microradiography were used to examine histological thin sections from the samples for comparison. PS-OCT successfully measured the formation of a layer of increased mineral content near the lesion surface. PLM and TMR corroborated those results. This study demonstrates the potential use of PS-OCT for the nondestructive measurement of the remineralization of dentin surfaces.