Mark D. Hewko

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A new technique based on polarized Raman spectroscopy is demonstrated for detecting early dental caries on extracted human teeth. Sound tooth enamel exhibited strong Raman polarization anisotropy whereas early caries consistently showed a lower degree of Raman polarization anisotropy. In particular, for sound enamel, the Raman peak arising from the(More)
Early dental caries detection will facilitate implementation of nonsurgical methods for arresting caries progression and promoting tooth remineralization. We present a method that combines optical coherence tomography (OCT) and Raman spectroscopy to provide morphological information and biochemical specificity for detecting and characterizing incipient(More)
In this study we present an image analysis methodology capable of quantifying morphological changes in tissue collagen fibril organization caused by pathological conditions. Texture analysis based on first-order statistics (FOS) and second-order statistics such as gray level co-occurrence matrix (GLCM) was explored to extract second-harmonic generation(More)
A new fibre-optic coupled polarization-resolved Raman spectroscopic system was developed for simultaneous collection of orthogonally polarized Raman spectra in a single measurement. An application of detecting incipient dental caries based on changes observed in Raman polarization anisotropy was also demonstrated using the developed fibre-optic Raman(More)
For decades there has been an ongoing search for clinically acceptable methods for the accurate, non-invasive diagnosis and prognosis of periodontitis. There are several well-known inherent drawbacks with current clinical procedures. The purpose of this review is to summarize some of the newly emerging diagnostic approaches, namely, infrared spectroscopy,(More)
Fourier transform infrared microscopy has been applied to the characterization of hypercholesterolemic rabbit liver. A combination of the traditional "group frequency" approach to spectral interpretation and the technique of functional group mapping was applied to aid understanding of the spectral changes observed between normal and hypercholesterolemic(More)
Optical coherence tomography imaging is used to improve the detection of incipient carious lesions in dental enamel. Measurements of signal attenuation in images acquired with an 850-nm light source were performed on 21 extracted molars from eight human volunteers. Stronger attenuation was observed for the optical coherence tomography (OCT) signal in(More)
Dental caries continues to be a common chronic disease among various population groups. Patient care can be improved with detection at the earliest stage. However, current techniques do not have sufficient sensitivity and specificity. We discuss 2 new methods - optical coherence tomography (OCT) and polarized Raman spectroscopy (PRS) - that are potentially(More)
The advantages and limitations of using a beating heart model in the development of intravascular optical coherence tomography are discussed. The model fills the gap between bench experiments, performed on phantoms and excised arteries, and whole animal in-vivo preparations. The beating heart model is stable for many hours, allowing for extended measurement(More)
Quantification of atherosclerosis has been a challenging task owing to its complex pathology. In this study, we validated a quantitative approach for assessing atherosclerosis progression in a rabbit model using a numerical matrix, optical index for plaque burden, derived directly from the nonlinear optical microscopic images captured on the(More)