In vitro study of the diagnostic performance of the Spectra Caries Detection Aid

The Spectra Caries Detection Aid is a fluorescent camera (FC) caries detector device that has been demonstrated to detect occlusal caries extending into dentin with good sensitivity and specificity. This in vitro study examined the diagnostic performance of this device with the goal of defining the numerical reading that best indicates that a tooth has dentin caries.

Ninety extracted human third molars, that either appeared clinically intact or had early occlusal caries, were used. Teeth were photographed then analyzed using the Spectra Caries detector. Following Spectra readings, the teeth were sectioned perpendicular to the long axis of the tooth. Cuts were made in such a way as to expose the dentino-enamel junction below the pits and fissures. The sectioned teeth were scored as being caries-free, having enamel caries, or dentin caries. Using each tooth's Spectra reading and histological diagnosis, the sensitivity and specificity for various potential dentin caries cut-off values were calculated. Also, the receiver operator curve (ROC) was plotted and the area under the curve calculated.

At the manufacture's recommended cut-off for dentin caries diagnosis of 2, the sensitivity is 0.68 and the specificity is 0.78. At a lower cut-off value in the study reported here of 1.8, it was observed that the sensitivity is higher at 0.87, but that the specificity is lower at 0.7. The overall diagnostic performance of the Spectra is good with an ROC area under the curve of 0.82.

Although lower cut-off values may have higher sensitivity, the use of the manufacture's established cut-off of 2 will result in fewer instances where dentin caries will be diagnosed incorrectly. The use of higher thresholds will discourage restorative treatment of early lesions that are best managed by sealants or other preventive approaches.