In vivo study of pixel grey-measurement in digital subtraction radiography for monitoring caries remineralization.

The aim of this study was to evaluate the performance of a quantitative method, based on pixel grey value measurements, for monitoring caries remineralization. Proximal radiographs of 11 patients (61 enamel caries lesions) were taken both before and after a 2 month remineralization protocol. Radiographs were digitized and for each area a follow-up image was subtracted from a baseline image. A quantitative analysis was undertaken using ImageTool software (University of Texas Health Science Center, San Antonio, TX). For each caries lesion diagnosed, a mean pixel value was obtained in digital subtraction radiographs (SR) using a scale ranging from 0-255 grey values. To identify caries status after the remineralization protocol, a subjective analysis of SR was undertaken by 6 radiologists who graded the lesions as demineralized (n = 10), unchanged (n = 34) or remineralized (n = 17). There was a statistically significant difference between the mean pixel values for demineralized (112.1+/-14.4), unchanged (127.3+/-12.3) and remineralized (137.5+/-13.8) lesions. It was concluded that the status of proximal caries lesions after remineralization therapy can be assessed by pixel grey measurements in SR and may constitute a suitable complementary method for monitoring the results of remineralization protocol in clinical practice.