Multi-Centre Clinical Evaluation of Photothermal Radiometry and Luminescence Correlated with International Benchmarks for Caries Detection

Josh D. Silvertown1, Stephen H. Abrams1, 2, *, Koneswaran S. Sivagurunathan1, Julia Kennedy1, Jinseok Jeon1, Andreas Mandelis1, 3, Adam Hellen1, 2, Warren Hellen2, Gary Elman4, Richard Ehrlich5, Raffy Chouljian6, Yoav Finer7, 8, Bennett T. Amaechi9
1 Quantum Dental Technologies Inc, Toronto, Ontario, Canada
2 Cliffcrest Dental Office, Scarborough, Ontario, Canada
3 Center for Advanced Diffusion Wave and Photoacoustic Technologies (CADIPT), University of Toronto, Ontario, Canada
4 Downsview Plaza Dental Office, Toronto Ontario, Canada
5 Elm Tree Dental, Caledon, Ontario, Canada
6 Scarborough North Dental Group, Toronto, Ontario, Canada
7 Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
8 Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
9 University of Texas Health Science Center, San Antonio, Texas, USA

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Creative Commons License
© 2017 Silvertown et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Quantum Dental Technologies Inc, 748 Briar Hill Avenue, Toronto, ON, M6B-1L3, Canada, Tel: 416-785-4547, E-mails:;



A clinical study was initiated to investigate a caries detection device (The Canary System (CS)), based on photothermal radiometry and modulated luminescence (PTR-LUM). The primary objective of this study was to determine if PTR-LUM values (in the form of Canary Numbers; CN) correlate with International Caries Diagnostic and Assessment System (ICDAS II) scores and clinical situations. The secondary objectives of this study were to monitor the safety of PTR-LUM, and collect data to determine how CN values could be used to differentiate healthy from decayed tooth surfaces on a normalized scale.


The trial was a four site, non-blinded study. Data was collected from 92 patients, resulting in 842 scanned tooth surfaces over multiple appointments. Surfaces were assessed according to ICDAS II, and further stratified into five clinical situation categories: 1) healthy surface, 2) non-cavitated white and/or brown spots; 3) caries lesions; 4) cavitation and 5) teeth undergoing remineralization therapy.

CN data was analyzed separately for smooth and occlusal surfaces. Using a semi-logarithmic graph to plot raw CN (rCN) and normalized (CN) values, rCN data was normalized into a scale of 0-100.


Linear correlations (R2) between CN and ICDAS II groupings for smooth and occlusal surfaces were calculated as 0.9759 and 0.9267, respectively. The mean CN values derived from smooth (20.2±0.6) and occlusal (19±1.0) surfaces identified as healthy had significantly lower CN values (P<0.05) compared with the values from the other clinical situation categories. No adverse events were reported.


The present study demonstrated the safety of PTR-LUM for clinical application and its ability to distinguish sound from carious tooth surfaces. A clear shift from the baseline in both PTR and LUM in carious enamel was observed depending on the type and nature of the lesion, and correlated to ICDAS II classification codes, which enabled the preliminary development of a Canary Scale.

Keywords: PTR-LUM, ICDAS-II, The Canary System, Canary Number, Caries lesion, Diagnostic.