Feasibility of micro-computed tomography to detect and classify proximal caries lesions in vitro .

Background: Micro-computed tomography (micro-CT) has been widely described as a nondestructive in vitro imaging method although its accuracy for caries detection is still unclear. The aim of this study was to investigate the feasibility of micro-CT to detect and classify proximal caries lesions in posterior teeth, using different protocols.

Materials and Methods: In this in vitro study, crowns of 122 human teeth were scanned with Skyscan 1174 (Bruker, Kontich, Belgium) using the full-scan mode (360°). Reconstruction of 900 basis images was performed using NRecon Software (Bruker, Kontich, Belgium) for the protocol 1 (full-scan mode 360°), and 450 basis images were used to reconstruct the protocol 2 (half-scan mode 180°). Three observers analyzed the reconstructed images concerning the presence and depth of proximal caries lesions (244 surfaces). To determine the presence/absence and depth of caries lesions, histological examination was conducted as reference standard level of significance McNemar and McNemar-Bowker tests compared the methods studied and the gold standard ( P < 0.05).

Results: The intra- and inter-observer agreement for both methods ranged from moderate to excellent. There was no difference between both micro-CT methods and histology for the presence of lesions ( P > 0.05). However, both methods differed with the reference standard for depth ( P < 0.05). The disagreement occurred mostly in cases of enamel lesions. The highest diagnostic values were found for 180° rotation. Micro-CT performed well in detecting caries lesions compared to histology, meanwhile the classification of their depth presented lower values. Scan mode did not influence the detection.

Conclusion: Both protocols of micro-CT tested presented an overall satisfactory performance in detecting proximal caries lesions; however, for the depth classification, the method was not accurate.