Thermal Imaging of Root Caries In Vivo

Abstract

Improved methods are needed to assess the structure and activity of lesions on root surfaces in order to improve clinical decision making. Conventional visual and tactile methods for assessing lesion activity are not reliable, and the clinician is often unable to evaluate if the lesion is progressing or has remineralized. An important marker of an arrested lesion is a highly mineralized surface zone that forms when mineral is deposited in the outer layer of the lesion. In vitro studies have shown that a mineralized surface zone influences the kinetics of water evaporation and the surface temperature while drying. Temperature changes can be monitored by measuring the thermal emission with thermal imaging. Studies have also shown that the depth and severity of demineralization and the thickness of the highly mineralized transparent surface zone on arrested lesions can be measured nondestructively with optical coherence tomography (OCT). Thermal imaging at 8-µm to 13-µm wavelengths was completed on 30 test subjects with a suspected active root caries lesion by monitoring thermal emission from the tooth surfaces during 30 s of air drying. Lesions were also evaluated using cross-polarization OCT (CP-OCT) during lesion dehydration to identify transparent surface zones indicative of arrested lesions and determine if shrinkage occurred during drying. The overall thermal emission recorded during drying was significantly different ( P < 0.001) when comparing sound tooth surfaces, lesion areas identified as arrested, and lesion areas identified as active, demonstrating that thermal imaging is a promising approach for the clinical assessment of lesion activity on root surfaces. Ten of the lesions in this study had distinct areas with transparent surface zones that were visible in CP-OCT images. Shrinkage was detected with CP-OCT during drying for 12 lesions. This study confirms that these novel approaches for assessing lesion activity on root surfaces can be implemented in vivo.

Dynamic SWIR imaging near the 1950-nm water absorption band for caries lesion diagnosis

“…In addition, the large distance of the nozzle for the in-vitro system (4 cm) used in this study yields a much lower effective pressure at the lesion surface, whereas the nozzle located on clinical probes is located less than a centimeter from the lesion during dehydration. 17 Fig. 6 3D scatter plot of the %I fin , OGR, and delay.…”

“…In-vivo studies have been published utilizing the fluorescence loss of white spot lesions on coronal surfaces 6 and thermal imaging to assess root caries during dehydration. 17 There is a negative association between the surface zone thickness and lesion permeability; a small increase in the surface layer thickness of can lead to a marked decrease in permeability. 18 In addition, in a closely related study, the surface zone was removed from arrested lesions, producing a corresponding rise in the permeability, which provided further confirmation of the role of the surface zone in arresting lesions.…”

High Contrast Reflectance Imaging of Enamel Demineralization and Remineralization at 1950‐nm for the Assessment of Lesion Activity

“…Changes in fluorescence loss [18‐20], thermal emission, and short‐wavelength infrared (SWIR) reflectance [21‐23] during lesion dehydration have been investigated as methods for assessing lesion activity. In vivo studies have been published utilizing the fluorescence loss of white spot lesions on coronal surfaces [20] and thermal imaging to assess root caries during dehydration [24]. The relationship between surface zone thickness and lesion permeability is highly non‐linear; a small increase in the surface layer thickness can lead to a marked decrease in permeability [25].…”

Artificial intelligence in digital cariology: a new tool for the diagnosis of deep caries and pulpitis using convolutional neural networks

“…Although the diagnosis of the cases included in the study was determined unanimously by a panel of three endodontists with over ten years of clinical experience following clinical guidelines (20), it cannot serve as the gold standard for the diagnosis of deep caries and pulpitis. Histological testing, such as pathological section, has been considered to be the gold standard for diagnosing of deep caries and pulpitis, but it requires the destruction of the tooth and is, therefore, not convenient in clinical practice (36). This study focused on the teeth with single carious lesion.…”