Photoacoustic imaging of hidden dental caries using visible–light diode laser

Abstract

Background: Hidden caries is a type of tooth decay that is difficult to identify through visual diagnosis because teeth with hidden caries appear normal on the tooth surface but are damaged underneath. Methods: A photoacoustic imaging system based on visible light using a diode laser with a wavelength of 532 nm was developed to detect hidden caries in teeth. Results:The results indicate that the average of acoustic intensity level for healthy teeth is −74.2 ± 0.1 dB, and the average of acoustic intensity range for teeth with hidden caries is −81.2 ± 0.5 dB. The intensity level for the caries area varies depending on the severity of caries. Conclusion:Based on the acoustic intensity level measured by the interaction of teeth with laser light, the photoacoustic imaging system in the study can accurately detect the presence of hidden caries and recognize the difference between caries teeth and healthy teeth. This research can be developed into a prototype of a simple device that makes it easy to operate in dental practice.

Recent development of photoacoustic imaging in dentistry: A review on studies over the last decade

“…Table 1 summarizes the data taken from the selected studies. Most studies focus on the ex-vivo application of PAI for the detection of tooth decay ( Arabpou et al, 2019 , Cheng et al, 2016 , El-Sharkawy and El Sherif, 2012 , Khosroshahi and Valizadeh, 2020 , Koyama et al, 2018 , Li and Dewhurst, 2016 , Periyasamy et al, 2018 , Rao et al, 2011 , Sampathkumar et al, 2014 , da Silva et al, 2021 , Tasmara et al, 2023 , Yamada et al, 2016 ). In general, clinical studies of PAI in dentistry assess the pocket depth of periodontal tissues from humans ( Fu, Khazaeinezhad et al, 2022 , Fu, Ling et al, 2022 , Fu et al, 2021 , Lin et al, 2017 , Moore et al, 2018 , Moore et al, 2022 , Mozaffarzadeh et al, 2021 ), and ex-vivo investigations employ samples from human teeth ( Alifkalaila et al, 2021 , Arabpou et al, 2019 , Cheng et al, 2016 , Dias et al, 2018 , El-Sharkawy and El Sherif, 2012 , Khosroshahi and Valizadeh, 2020 , Koyama et al, 2018 , Lee et al, 2017 , Li and Dewhurst, 2016 , Periyasamy et al, 2018 , Rao et al, 2011 , Sampathkumar et al, 2014 , da Silva et al, 2021 , Yamada et al, 2016 ), animal model for mimicking periodontal diseases ( Sari et al, 2022 ), and oral soft tissues from rats ( Widyaningrum et al, 2018 , Widyaningrum et al, 2020 ).…”

“…This system has some limitations due to the low signal-to-noise ratio in blood, which affects many small-molecule photoacoustic probes. Tasmara et al (2023) PAI to detect hidden caries. Diode laser with 532 nm 200 mW and condenser microphone as a detector.…”

“…Meanwhile, the acoustic signal of carious teeth had a higher prevalence than normal teeth ( El-sharkawy et al, 2006 ). PAI has been investigated to detect tooth decay and hidden caries ( Tasmara et al, 2023 ). To date, PAI has not been widely adopted in dentistry.…”

Thermal conductivity measurement experiment of metal using heat sensor and Arduino

“…The heating method used is conduction where the object is directly in contact with the heat source. Conduction is a type of heat transfer where energy transfer occurs in objects or fluid objects that are at rest (no convection transfer comes from the transfer of macroscopic portions of the medium) which flows from a high temperature area to a lower area [5]. The rate of heat flow cannot be measured directly, but the concept has physical significance as it relates to the measurable scalar quality of temperature.…”

Resonance frequency measurement to identify stiffness variations based on photoacoustic imaging

“…This study aims to develop a non-contact measurement system based on photoacoustic techniques to detect differences in soft tissue phantom stiffness based on the results of image reconstruction at the resonance frequency. The photoacoustic signal is detected by the microphone as an air-coupled transducer, enabling non-contact measurements [ 10 , 11 ]. Phantom samples are objects designed to mimic the properties of biologic tissues, such as acoustic impedance, acoustic propagation velocity, and attenuation coefficient.…”