Desktop X-ray micro CT imaging compared against conventional histological sectioning as a gold standard in cardiology

Conventional histological validation is a generally accepted gold standard in caries studies. Besides demanding complex laboratory processing, about 80% of the tooth material is lost irreversibly by sectioning and polishing. X-ray Micro Computer Tomography (XMT) is a high-resolution, non-destructive imaging technique, not requiring elaborate specimen preparation. Today's commercial desktop XMT systems significantly reduced the cost and complexity of the technique. The aim of the present study is to compare both methods for categorical caries gradation and assessment of lesion depth and size.
148 extracted human premolars and molars, encompassing lesions of different extent, were selected. All teeth were individually mounted on a support structure such as to ensure identical cross-sectional orientation during XMT and histological preparation. After obtaining XMT images with spatial resolution of 18µm3 (Skyscan 1076, Skyscan NV, Kontich, Belgium), all teeth were embedded in resin and serially sectioned (final thickness ? 100µm), with digital photographs being taken of each section. Custom registration software allowed accurate correlation of histological sections with corresponding XMT images. Both sets of images were displayed in randomized order on a 21'' CRT monitor. Four observers scored lesion category, and marked central depth as well as lesion area, using a proprietary graphical user interface.
XMT yielded 453 sound surfaces, 69 with enamel and 79 with dentine caries. Histology showed 406 sound surfaces, 89 with enamel caries, and 95 with dentine caries. Spearman's correlation coefficients ranged from 0.751 to 0.867 (pDue to its nondestructive nature and comparatively simple specimen manipulation, desktop XMT imaging seems a promising alternative to histology as a gold standard in cariology.