Enamel Caries Lesion Depth Obtained by Optical Coherence Tomography and Transverse Microradiography: A Comparative Study

Abstract

<b><i>Introduction:</i></b> Visual imaging of subsurface caries lesions is of vital interest in dentistry, which can be obtained by invasive radiography technique as well as by available non-destructive imaging approaches. Thus, as a first step toward the development of a new innovative approach, Spectral-domain optical coherence tomography (SD-OCT) was applied to detect the lesion depth in comparison to the established reference technique (transverse microradiography [TMR]). <b><i>Methods:</i></b> Bovine enamel specimens were demineralized for 5 days, following previous studies. For OCT, the resulting artificial lesions were scanned three-dimensionally (SD-OCT) and semi-automated measured (CarLQuant). For TMR, specimens were sectioned and the lesion depth was manually determined (Inspektor Research System). <b><i>Results:</i></b> The range of lesion depth detected with OCT was 24.0–174.0 μm (mouth rinse study), 18.0–178.0 μm (toothpastes study) and with TMR 59.2–198.0 μm (mouth rinse study), 33.2–133.4 μm (toothpastes study). We found a strong correlation between both methods in terms of lesion depth (Spearman rank<sub>with outlier</sub><i>p</i> < 0.001, Rho = 0.75, Spearman rank<sub>without outlier</sub><i>p</i> = 0.001, Rho = 0.79). The two methods produce similar results (Passing-Bablok regression, 1.16). As deeper is the lesion, the smallest is the difference between both methods as indicated by Bland-Altman-plots. <b><i>Conclusion:</i></b> Especially in the case of deep lesions, the values obtained by both methods are in agreement, and OCT can potentially substitute TMR to detect and assess lesion depth with the benefit of being non-destructive.