An ex vivo comparative study of occlusal and proximal caries using terahertz and X-ray imaging
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Objectives:: To examine the effectiveness of terahertz (THz) pulsed imaging (TPI) in comparison to intraoral photostimulable phosphor late (PSP) and cone beam CT (CBCT) for the detection of dental caries ex vivo. Methods:: Newly extracted 32 human permanent teeth surfaces (16 with caries and 16 without caries) were serially sectioned mesiodistally and imaged by using four image sets as follows: (1) CBCT; (2) PSP; (3) THz movie video; and (4) THz static images. All images were evaluated twice separately by two calibrated observers for the presence/absence of caries using a 5-grade rating/confidence scale. Weighted κ coefficients were calculated. Different image sets were compared with the histological gold-standard using the receiver operating characteristic and area under curves for each image set were compared using χ2 tests, with a significance level of α = 0.05. Results:: Intra- and interobserverκ-values for all image sets were almost excellent ranging between 0.777 and 0.988. Mean Az values of observers and readings were 0.898 for CBCT, 0.888 for PSP images, 0.853 for THz static images and 0.781 for THz video movie. No statistically significant differences (p > 0.05) were found between Az values for the different image sets. When observer scores were evaluated according to caries location again no statistically significant differences (p > 0.05) were found between Az values for the occlusal and proximal caries for the four image sets. Conclusions:: Terahertz pulsed imaging was found to be successful for the detection of dental caries ex vivo.