Diagnosis of Pit and Fissure Caries Using Frequency-Domain Infrared Photothermal Radiometry and Modulated Laser Luminescence

Abstract

Non-intrusive, non-contacting frequency-domain photothermal radiometry (FD-PTR or PTR) and frequency-domain luminescence (FD-LUM or LUM) have been used with 659- and 830-nm laser sources to assess the pits and fissures on the occlusal surfaces of human teeth. Fifty-two human teeth were examined with simultaneous measurements of PTR and LUM and were compared to conventional diagnostic methods including continuous (dc) luminescence (DIAGNOdent), visual inspection and radiographs. To compare each method to the others, sensitivities and specificities were calculated by using histological observations as the gold standard. With the combined criteria of four PTR and LUM signals (two amplitudes and two phases), it was found that the sensitivity of this method was much higher than any of the other methods used in this study, whereas the specificity was comparable to that of dc luminescence diagnostics. Therefore, PTR and LUM, as a combined technique, has the potential to be a reliable tool to diagnose early pit and fissure caries and could provide detailed information about deep lesions. Using the longer wavelength (830-nm) laser source, it has been shown that detection of deeper subsurface lesions than the 659-nm probe provides is possible.

Alternative methods to visual and radiographic examinations for approximal caries detection

“…Black body radiation is a type of electromagnetic radiation surrounding or within a body in thermodynamic equilibrium with its environment or emitted by a black body when the temperature is uniform and constant. The radiation has a specific constant and intensity dependent only on the temperature of the body (74)(75)(76). A change in the temperature of the sample surface will occur as a result of the conversion of the absorbed radiation energy to thermal energy.…”

“…A change in the temperature of the sample surface will occur as a result of the conversion of the absorbed radiation energy to thermal energy. The change in the thermal emissions caused by the modulated temperature can be measured using an infrared detector that constitutes the PTR signal (75,76).…”

“…When a molecule absorbs optical energy from a laser source, it results in excitation of its chromophores to a higher energy state, followed by de-excitation to a lower energy state and emission of longer wavelength energy. This emitted longer wavelength can be detected by a photodetector, which constitutes the LUM signal (75,76).…”

In vitro Detection of Occlusal Caries on Permanent Teeth by a Visual, Light-Induced Fluorescence and Photothermal Radiometry and Modulated Luminescence Methods

“…The first response signifies the conversion of absorbed optical energy into thermal energy that results in a modulation in the temperature of tooth structure (PTR). The second response signifies the conversion of absorbed optical energy to radiative energy (LUM) [Jeon et al, 2004;Hellen et al, 2011]. In initial laboratory studies, PTR/LUM is reported to detect lesions as deep as 5 mm and is expressed on a scale of 0-100 to represent lesion severity.…”

Characterizing and Identifying Incipient Carious Lesions in Dental Enamel Using Micro-Raman Spectroscopy

“…Therefore, better diagnostic tools are needed to detect early carious lesions and help prevent dental cavities. Over the past few years, various techniques have been explored to address the need for better detection tools to diagnose early dental caries [Hill and Petrou, 2000;Crawley et al, 2003;Hall and Girkin, 2004;Jeon et al, 2004;Fried et al, 2005;Ko et al, 2005;Amaechi et al, 2011]. These techniques include direct digital radiography, digital imaging fiber-optic transillumination, quantitative light-induced fluorescence, laser-induced fluorescence, multiphoton imaging, infrared thermography, terahertz imaging, optical coherence tomography and Raman spectroscopy.…”