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Proceedings Paper

All-optical photoacoustic imaging and detection of early-stage dental caries
Author(s): Ashwin Sampathkumar; David A. Hughes; Chris Longbottom; Katherine Kirk
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Paper Abstract

Dental caries remain one of the most common oral diseases in the world. Current detection methods, such as dental explorer and X-ray radiography, suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease because of the small size (< 100 microns) of early-stage lesions. We have developed a fine-resolution (480 nm), ultra-broadband (1 GHz), all-optical photoacoustic imaging (AOPAI) system to image and detect early stages of tooth decay. This AOPAI system provides a non-contact, non-invasive and non-ionizing means of detecting early-stage dental caries. Ex-vivo teeth exhibiting early-stage, white-spot lesions were imaged using AOPAI. Experimental scans targeted each early-stage lesion and a reference healthy enamel region. Photoacoustic (PA) signals were generated in the tooth using a 532-nm pulsed laser and the light-induced broadband ultrasound signal was detected at the surface of the tooth with an optical path-stabilized Michelson interferometer operating at 532 nm. The measured time-domain signal was spatially resolved and back-projected to form 2D and 3D maps of the lesion using k-wave reconstruction methods. Experimental data collected from areas of healthy and diseased enamel indicate that the lesion generated a larger PA response compared to healthy enamel. The PA-signal amplitude alone was able to detect a lesion on the surface of the tooth. However, time- reversal reconstructions of the PA scans also quantitatively depicted the depth of the lesion. 3D PA reconstruction of the diseased tooth indicated a sub-surface lesion at a depth of 0.6 mm, in addition to the surface lesion. These results suggest that our AOPAI system is well suited for rapid clinical assessment of early-stage dental caries. An overview of the AOPAI system, fine-resolution PA and histology results of diseased and healthy teeth will be presented.

Paper Details

Date Published: 24 February 2015
PDF: 7 pages
Proc. SPIE 9306, Lasers in Dentistry XXI, 93060E (24 February 2015); doi: 10.1117/12.2079765
Show Author Affiliations
Ashwin Sampathkumar, Riverside Research Institute (United States)
David A. Hughes, Univ. of West Scotland (United Kingdom)
Chris Longbottom, King's College London (United Kingdom)
Katherine Kirk, Univ. of the West of Scotland (United Kingdom)

Published in SPIE Proceedings Vol. 9306:
Lasers in Dentistry XXI
Peter Rechmann; Daniel Fried, Editor(s)

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