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Photothermal diffusion-wave imaging is a promising technique for non-destructive evaluation and medical applications. Several diffusion-wave techniques have been developed to produce depth-resolved planar images of solids and to overcome imaging depth and image blurring limitations imposed by the physics of parabolic diffusion waves. Truncated-Correlation Photothermal Coherence Tomography (TC-PCT) is the most successful class of these methodologies to-date providing 3-D subsurface visualization with maximum depth penetration and high axial and lateral resolution. To extend the depth range and axial and lateral resolution, an in-depth analysis of TC-PCT, a novel imaging system with improved instrumentation, and an optimized reconstruction algorithm over the original TC-PCT technique is developed. Thermal waves produced by a laser chirped pulsed heat source in a finite thickness solid and the image reconstruction algorithm are investigated from the theoretical point of view. 3-D visualization of subsurface defects utilizing the new TC-PCT system is reported. The results demonstrate that this method is able to detect subsurface defects at the depth range of ∼4 mm in a steel sample, which exhibits dynamic range improvement by a factor of 2.6 compared to the original TC-PCT. This depth does not represent the upper limit of the enhanced TC-PCT. Lateral resolution in the steel sample was measured to be ∼31 μm.

Aim The efficacy of self‐assembling peptide P11‐4 to regenerate enamel in natural early caries lesions was evaluated over 50 days by photothermal radiometry and luminescence using The Canary System (CS) and The Canary Lab (CL). Methods Baseline readings for sound and carious sites on smooth surfaces of extracted teeth were obtained by scanning with CS and CL. Teeth were then randomly assigned to a treatment group (TG, treated with P11‐4), a placebo group (PG, same vehicle as treatment group without P11‐4), or a control group (CG, no treatment). All the teeth were then placed in artificial saliva to facilitate natural remineralization, and the sites were rescanned with CS and CL at 7, 14, 30, and 50 days. Results For carious sites in TG, mean canary numbers (CN) derived from CS decreased significantly (P<.01) from 44±3.8 at baseline to 24±4.9 at day 50; the mean CN for the TG derived from CL also decreased significantly (P<.05), from 65 at baseline to 45 at day 50. In contrast, no significant changes in CN were observed for carious sites in the CG or PG using either CS or CL. Conclusions P11‐4 promoted the regeneration of early caries.

Introduction:The aim of this study was to correlate lesion depth of natural caries, measured with Polarized Light Microscopy (PLM), to Canary Numbers (CN) derived from The Canary System™ (CS), numerical readings from DIAGNOdent (DD), and lesion scores from ICDAS II.Methods:A total of 20 examination sites on extracted human molars and premolars were selected. The selected examination sites consisted of healthy and enamel caries on smooth and occlusal surfaces of each tooth. Two blinded dentists ranked each examination site using ICDAS II and the consensus score for each examined site was recorded. The same examination sites were scanned with CS and DD, and the CN and DD readings were recorded. After all the measurements were completed, the readings of the three caries detection methods were validated with a histological method, Polarized Light Microscopy (PLM). PLM performed by blinded examiners was used as the ‘gold standard’ to confirm the presence or absence of a caries lesion within each examined site and to determine caries lesion depth.Results:Pearson’s coefficients of correlation with caries lesion depth of CNs, DD readings and ICDAS scores were 0.84, 0.21 and 0.77, respectively. Mean ± SD CN for sound sites (n=3), caries lesion depths <800 µm (n=11), and caries lesion depths >800 µm (n=6) were 11±1, 55±15, and 75±22, respectively. Mean ± SD DD readings for sound sites, caries lesion depths <800 µm, and caries lesion depths >800 µm were 1±1, 7±11, and 8±9, respectively. Mean ± SD ICDAS II scores for sound sites, caries lesion depths <800 µm, and caries lesion depths >800 µm were 0±0, 2±1, and 2±1, respectively. The intra-operator repeatability for the Canary System was .953 (0.913, 0.978).Conclusion:This study demonstrated that the CS exhibits much higher correlation with caries lesion depth compared to ICDAS II and DD. CS may provide the clinician with more information about the size and position of the lesion which might help in monitoring or treating the lesion.The present extracted tooth study found that The Canary System correlates with caries lesion depth more accurately that ICDAS II and DIAGNOdent.

The Canary System can serve as a clinical tool to aid dental professionals to detect and monitor the status of caries lesions and tooth structure underneath sealant. The increased likelihood of false-positive diagnoses with DIAGNOdent due to intrinsic auto-fluorescence of sealant filler and opacifying agents might limit its usefulness as an aid to detect caries underneath opaque sealants.