An optical coherence tomography (OCT) system with a prototype dental probe was used to image fresh, frozen porcine jaws to evaluate the ability to identify different tissue types in the periodontium. OCT reliably imaged structures in the tooth and the periodontium to optical depths of approximately 3 mm at the 18 swine premolar sites measured. Measurements of the cemento-enamel junction (CEJ) to alveolar crest (AC) distance with OCT were compared to microphotography measurements at matching anatomic sites. Strong correlation between the measurements was observed (Person correlation r=0.89). Bland-Altman analysis of the agreement between measurements showed good agreement, no systematic bias, and zero fixed bias (p<0.01). This pilot study suggests OCT may be used to optically, non-invasively monitor periodontal conditions, in particular changes in alveolar bone level as measured by the CEJ-AC distance, in real time.
Internal adaptation of adhesive restorations affects their longevity. In a clinical setting, the dentists use visual and tactile examination to evaluate marginal adaptation, while radiographs provide somewhat reliable information about adaptation or secondary caries present. For class V restorations located on the vestibular (buccal) surfaces, none of the tools available can provide any information about the internal adaptation or the presence of secondary caries. OCT has been proven to be a useful tool for non-destructive assessment of internal adaptation of adhesive restorations. This paper is evaluating the use of a new high-resolution handheld OCT prototype with a pen-shaped intraoral tip and an imaging depth of 8mm to examine the internal adaptation and the presence of demineralization under resin restorations on the vestibular dentin surface. The Axsun OCT system helped evaluate the internal adaptation of composite restorations, differentiate between healthy and demineralised dentin, adhesive, and restoration layers. OCT provided a unique visualization and characterization of internal structures as well as non-contact assessment of marginal adaptation.
Near infrared imaging methods, including optical coherence tomography (OCT), have shown promise in assessing activity of enamel caries lesions. We present initial results in ex-vivo dental samples with a polarization diversity-detection OCT system complete with an integrated dental handpiece. Built around an Axsun Technologies swept source engine, images B-scans 12(x) by 7(z) mm at over 100 fps with 66um transverse and 7um depth resolution. Internal normal dental structure and lesions were imaged and compared with micro-CT. We demonstrate that the Axsun OCT prototype can detect the penetration of occlusal lesions to dentin and measure the penetration of approximal lesions when imaging from the occlusal surface.
Cytology tests, whether performed on body fluids, aspirates, or scrapings are commonly used to detect, diagnose, and monitor a wide variety of health conditions. Complete blood counts (CBCs) quantify the number of red and white blood cells in a blood volume, as well as the different types of white blood cells. There is a critical unmet need for an instrument that can perform CBCs at the point of care (POC), and there is currently no product in the US that can perform this test at the bedside. We have developed a system that is capable of tomographic images with sub-cellular resolution with consumer-grade broadband (LED) sources and CMOS detectors suitable for POC implementation of CBC tests. The systems consists of cascaded static Michelson and Sagnac interferometers that map phase (encoding depth) and a transverse spatial dimension onto a two-dimensional output plane. Our approach requires a 5 microliter sample, can be performed in 5 minutes or less, and does not require staining or other processing as it relies on intrinsic contrast. We will show results directly imaging and differentiating unstained blood cells using supercontinuum fiber lasers and LEDs as sources and CMOS cameras as sensors. We will also lay out the follow up steps needed, including image segmentation, analysis and classification, to verify performance and advance toward CBCs that can be performed bedside and do not require CLIA-certified laboratories.
Rupture of lipid-rich arterial atheromas is believed to be the cause of most acute coronary events. We show that high sensitivity and specificity in the detection of these lesions is possible through whole blood varying from 0 to 3mm using near-infrared reflectance spectroscopy. This enables the use of a non-occlusive, intra-coronary catheter to screen high-risk patients to guide therapy.
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