New diagnostic tools are needed for the characterization of dental caries in the early stages of development. If carious lesions are detected early enough, they can be arrested without the need for surgical intervention. The objective of this study was to demonstrate that polarization sensitive optical coherence tomography (PS-OCT) can be used for the imaging of early caries lesions and for the monitoring of lesion progression over time. High-resolution polarization resolved images were acquired of natural caries lesions and simulated caries lesions of varying severity created over time periods of 1 to 14 days. Linearly polarized light was incident on the tooth samples and the reflected intensity in both orthogonal polarizations was measured. PS-OCT was invaluable for removing the confounding influence of surface reflections and native birefringence necessary for the enhanced resolution of the surface structure of caries lesions. This study demonstrated that PS-OCT is well suited for the imaging of interproximal and occlusal caries, early root caries, and for imaging decay under composite fillings. Longitudinal measurements of the reflected light intensity in the orthogonal polarization state from the area of simulated caries lesions linearly correlated with the square root of time of demineralization indicating that PS-OCT is well suited for monitoring changes in enamel mineralization over time.

New diagnostic tools are needed for the characterization of dental caries in the early stages of development. If carious lesions are detected early enough, they can be arrested without the need for surgical intervention. The objective of this study was to demonstrate that polarization sensitive optical coherence tomography (PS-OCT) can be used for the imaging of early caries lesions and for the monitoring of lesion progression over time. High-resolution polarization resolved images were acquired of natural caries lesions and simulated caries lesions of varying severity created over time periods of 1 to 14 days. Linearly polarized light was incident on the tooth samples and the reflected intensity in both orthogonal polarizations was measured. PS-OCT was invaluable for removing the confounding influence of surface reflections and native birefringence and for resolving the surface structure of caries lesions. This study demonstrated that PS-OCT is well suited for the resolution of interproximal and occlusal caries, early root caries, and secondary caries around composite fillings. Longitudinal measurements of lesion progression established a strong correlation (p<0.001) between the reflected light from the lesion area and the square root of time indicating that PS-OCT is well suited for monitoring changes in enamel mineralization over time.

Scaffolds derived from naturally occurring polysaccharides have attracted significant interest in bone tissue engineering due to their excellent biocompatibility and hydrophilic nature favorable for cell attachment. In this study, we developed composite chitosan (CH) scaffolds containing anionic carbohydrate, such as chondroitin 4-sulfate (CS) or alginate (AG), with biomimetic apatite layer on their surfaces, and investigate their capacity to deliver progenitor cells (bone marrow stromal cells, BMSC) and model proteins with net-positive (histone) and net-negative charge (bovine serum albumin, BSA). The incorporation of CS or AG in CH scaffolds increased compressive modulus of the scaffolds and enhanced apatite formation. Initial burst release of histone was significantly higher than that of BSA from CH scaffold, while the addition of CS or AG in the scaffolds significantly reduced the initial burst release of histone, indicating strong electrostatic interaction between histone and negatively charged CS or AG. The apatite layer created on scaffold surfaces significantly reduced the initial burst release of both BSA and histone. Furthermore, apatite-coated scaffolds enhanced spreading, proliferation, and osteogenic differentiation of BMSC seeded on the scaffolds compared to non-coated scaffolds as assessed by live/dead and alamarBlue assays, scanning electron microscopy (SEM), alkaline phosphatase (ALP) activity, and Picrosirius red staining. This study suggests that apatite-coated CH/CS composite scaffolds have the potential as a promising osteogenic system for bone tissue engineering applications.