Quantitative photothermal analysis and multispectral imaging of dental structures: insights into optical and thermal properties of carious and healthy teeth.

Significance: In the analysis of two-layered turbid dental tissues, the outer finite-thickness layer is modeled by an optical transport coefficient distinct from its underlying semi-infinite substrate layer. The optical and thermophysical parameters of healthy and carious teeth across the various wavelengths were measured leading to the determination of the degree of reliability of each of the fitted parameters, with most reliable being thermal diffusivity and conductivity, enamel thickness, and optical transport coefficient of the enamel layer. Quantitative pixel-by-pixel images of the key reliable optical and thermophysical parameters were constructed.

Three-dimensional thermophotonic super-resolution imaging by spatiotemporal diffusion reversal method.

Spatial super-resolution in thermophotonic imaging was achieved using a combination of spatial second-derivative forming, spatial gradient adaptive filtering, and Richardson-Lucy deconvolution in conjunction with the construction of an experimental point spread function. When implemented through enhanced truncation-correlation photothermal coherence tomography (eTC-PCT), it was possible to restore blurred infrared thermophotonic images to their prediffusion optical resolution state. This modality was tested in various biological applications and proved to be capable of imaging fine axial cracks in human teeth, well-patterned anatomical subsurface structures of a mouse brain, and neovascularization in a mouse thigh due to the rapid proliferation of cancer cells.

Detection of Bacteria-Induced Early-Stage Dental Caries Using Three-Dimensional Mid-Infrared Thermophotonic Imaging.

Tooth decay, or dental caries, is a widespread and costly disease that is reversible when detected early in its formation. Current dental caries diagnostic methods including X-ray imaging and intraoral examination lack the sensitivity and specificity required to routinely detect caries early in its formation. Thermophotonic imaging presents itself as a highly sensitive and non-ionizing solution, making it suitable for the frequent monitoring of caries progression.

Multispectral truncated-correlation photothermal coherence tomography imaging modality for detection of early stage dental caries.

One of the major oral health conditions worldwide is dental caries. Light-absorption-based thermophotonic diagnostic imaging is well positioned for this challenge thanks to its speed, safety, and high molecular contrast advantages. In this work, a multispectral (MS) truncated-correlation photothermal coherence tomography (TC-PCT) imaging modality is introduced for the detection of bacterial-induced dental caries.

Three-dimensional thermophotonic image optimization modalities of truncated correlation photothermal coherence tomography.

Truncated correlation photothermal coherence tomography (TC-PCT) is a pulse-compression, matched-filter-based photothermal diffusion-wave imaging modality with a proven track record in non-destructive evaluation of biomedical, dental, art-object and industrial applications. This is a study of the effect thermal transient truncation plays in the TC-PCT algorithm. It introduces a new phase channel which was coined the name Linear Iso Phase (LIOP) and improves the conventional TC-PCT phase by redevising its matched-filter sampling scheme and removing the effect of circular aliasing artifacts introduced in the frequency-domain-transformed cross-correlation (CC) calculations.

Comparison of Long-Wave and Mid-Wave Infrared Imaging Modalities for Photothermal Coherence Tomography of Human Teeth.

The ability to detect dental caries at early stages lies at the heart of minimal intervention dentistry, enabling the curing or arresting of carious lesions before they advance to the cavity stage. Enhanced truncated-correlation photothermal coherence tomography (eTC-PCT) using mid-wave infrared (MWIR) cameras has recently been shown to offer tomographic visualization of early caries. The tomographic slicing ability of such systems, however, is believed to be limited by direct radiative thermal emission through the translucent dental enamel in the 3-5 µm MWIR spectral range.

Truncated correlation photoacoustic coherence tomography: An axial resolution enhancement imaging modality.

In this report we present a novel photoacoustic (PA) modality using pulsed chirp excitation at a fixed wavelength and spectral analysis based on frequency-domain (FD) processing. We introduce Truncated Correlation Photoacoustic Coherence Tomography (TC-PACT), a PA axial resolution enhancement methodology, with an application to closely stacked subsurface multilayers of plexiglass coated with a thin layer of graphite acting as surface absorber. The experimental results demonstrated that the SNR and the axial resolution were higher in TC-PACT than in conventional FD photoacoustics.

Detection and monitoring of early dental caries and erosion using three-dimensional enhanced truncated-correlation photothermal coherence tomography imaging.

Significance: Dental caries is the most common oral disease, with significant effects on healthcare systems and quality of life. Developing diagnostic methods for early caries detection is key to reducing this burden and enabling non-invasive treatment as opposed to the drill-and-fill approach.

Aim: The application of a thermophotonic-based 3D imaging modality [enhanced truncated-correlation photothermal coherence tomography (eTC-PCT)] to early dental caries is investigated.

3D Dental Subsurface Imaging Using Enhanced Truncated Correlation-Photothermal Coherence Tomography.

Development of accurate and sensitive dental imaging technologies is a top priority in the pursuit of high-quality dental care. However, while early dental caries detection and routine monitoring of treatment progress are crucial for effective long-term results, current radiographic technologies fall short of this objective due to low sensitivity for small lesions and use of ionizing radiation which is unsuitable for frequent monitoring. Here we demonstrate the first application of enhanced Truncated Correlation-Photothermal Coherence Tomography (eTC-PCT) to dental imaging.

Noninvasive in vivo glucose detection in human finger interstitial fluid using wavelength-modulated differential photothermal radiometry.

We present a noninvasive and noncontacting biosensor using Wavelength Modulated Differential Photothermal Radiometry (WM-DPTR) to monitor blood glucose concentration (BGC) through interstitial fluid (ISF) probing in human middle fingers. WM-DPTR works in the interference-free mid-infrared range with differential wavelengths at the peak and baseline of the fundamental glucose molecule absorption band, giving rise to high glucose sensitivity and specificity. In vivo WM-DPTR measurements and simultaneous finger pricking BGC reference measurements were performed on diabetic and nondiabetic volunteers during oral glucose tolerance testing.

Truncated-correlation photothermal coherence tomography derivative imaging modality for small animal in vivo early tumor detection.

Early cancer non-invasive diagnosis is a leading medical topic worldwide due to the threat to human life and the high death rate of this disease. Light-absorption-based thermophotonic diagnostic imaging is well positioned for this challenge thanks to its speed, safety, and high molecular contrast advantages. In this Letter, an enhanced truncated-correlation photothermal coherence tomography (TC-PCT) imaging modality is presented for early in vivo tumor detection and tested using a nude mouse thigh.

Highly sensitive and specific noninvasive alcohol detection using wavelength-modulated differential photothermal radiometry.

This paper reports the application of wavelength modulated differential photothermal radiometry (WM-DPTR) to blood alcohol (ethanol) concentration (BAC) measurements in the mid-infrared range to prevent impaired driving. alcohol consumption measurements performed in the BAC range of interest (0-80 mg/dl) with an optimal wavelength pair demonstrated the alcohol detection capability of WM-DPTR with high resolution (~5 mg/dl) and a low detection limit (~10 mg/dl). Oral glucose tolerance tests using both glucose and alcohol sensitive wavelength pairs in the normal-to-hyperglycemia range (~80-320 mg/dl) proved the blood glucose screening ability and ethanol detection specificity of WM-DPTR.

Detection of Caries Around Resin-Modified Glass Ionomer and Compomer Restorations Using Four Different Modalities In Vitro.

The aim of this study was to evaluate the ability of visual examination (International Caries Detection and Assessment System-ICDAS II), light-emitting diodes (LED) fluorescence (SPECTRA), laser fluorescence (DIAGNODent, DD), photothermal radiometry and modulated luminescence (PTR-LUM, The Canary System, CS) to detect natural decay beneath resin-modified glass ionomer (RMGIC) and compomer restorations in vitro. Twenty-seven extracted human molars and premolars, consisting of 2 control teeth, 10 visually healthy/sound and 15 teeth with natural cavitated lesions, were selected. For the carious teeth, caries was removed leaving some carious tissue on one wall of the preparation.

Single frequency thermal wave radar: A next-generation dynamic thermography for quantitative non-destructive imaging over wide modulation frequency ranges.

Single-Frequency Thermal Wave Radar Imaging (SF-TWRI) was introduced and used to obtain quantitative thickness images of coatings on an aluminum block and on polyetherketone, and to image blind subsurface holes in a steel block. In SF-TWR, the starting and ending frequencies of a linear frequency modulation sweep are chosen to coincide. Using the highest available camera frame rate, SF-TWRI leads to a higher number of sampled points along the modulation waveform than conventional lock-in thermography imaging because it is not limited by conventional undersampling at high frequencies due to camera frame-rate limitations.

Correlation with Caries Lesion Depth of The Canary System, DIAGNOdent and ICDAS II.

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.

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

Introduction: 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.

Detection of Caries Around Amalgam Restorations Using Four Different Modalities.

Objective: The aim of this study was to evaluate the ability of PTR-LUM (The Canary System, CS), laser fluorescence (DIAGNOdent, DD), LED fluorescence (Spectra), and visual inspection (ICDAS II) to detect natural decay around bonded amalgam restorations .

Methods: Seventeen extracted human molars and premolars, consisting of visually healthy (n=5) and natural cavitated (n=12) teeth were selected. For the carious teeth, caries was removed leaving some decayed tissue on the floor and or wall of the preparation.

Remineralization of natural early caries lesions in vitro by P -4 monitored with photothermal radiometry and luminescence.

Aim: The efficacy of self-assembling peptide P -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 P -4), a placebo group (PG, same vehicle as treatment group without P -4), or a control group (CG, no treatment).

Comparison of The Canary System and DIAGNOdent for the in vitro detection of caries under opaque dental sealants.

Aim: The aim of the present study was to investigate the ability of operators using The Canary System and DIAGNOdent to detect natural pit and fissure caries under four commonly-used opaque dental sealants.

Methods: Mixed sound and carious pits/fissures (N = 105) selected from 40 human teeth were randomly assigned (10 teeth/group) to one of four opaque sealant groups (Delton, Embrace WetBond, Helioseal F, UltraSeal XT Plus). Selected pits/fissures sites on occlusal surfaces were scanned with The Canary System and DIAGNOdent, sealed, re-scanned, and subjected to polarized light microscopy to confirm whether the scanned regions were sound or carious.