Dentin reactions to caries are misinterpreted by histological “gold standards”

Abstract

Dentin reactions to caries, crucial for pathogenesis and for the determination of the severity of caries lesions, are believed to be reasonably detected by stereomicroscopy (SM) and polarized light microscopy in quinoline (PLMQ), but accuracies are not available. Here, stereomicroscopy of wet (SW) and dry (SD) ground sections of natural occlusal caries lesions resulted in moderate (0.7, for normal dentin) and low accuracies (< 0.6, for carious and sclerotic dentin) as validated by contrast-corrected microradiography. Accuracies of PLMQ were moderate for both normal (0.71) and carious dentin (0.71). The hypothesis that detection of dentin reactions by SM and PLMQ would be influenced by the contrast quality of micrographic images was rejected. Dentin reactions were scored by SW, SD, PLMQ, and three types of microradiographic images with varying contrast qualities and each technique was compared against the one that resulted in the highest number of scores for each dentin reaction. Large differences resulted, mainly related to the detection of sclerotic dentin by both SW and SD, and normal and carious dentin by PLMQ. It is concluded that contrast-corrected microradiography should be preferred as the gold standard and SM and PLMQ should be avoided, but the relationship of PLMQ with dentin mineralization deserves further investigation.

Correlation between ICDAS and histology: Differences between stereomicroscopy and microradiography with contrast solution as histological techniques

“…The aspects of translucent dentin and dentin without yellowish/brownish discolorations under SM are not included in the depth of dentin demineralization measured with SM [ 1 – 2 ]. It has been shown, however, that translucent dentin can be either carious or sclerotic dentin [ 4 – 9 ], and that dentin translucency under SM is poorly correlated with dentin radiopacity under microradiography [ 9 ] (see also Fig 1 of Bjorndal, Darvann & Thylstrup, 1988) [ 10 ]. The microradiographic identification of radiolucent dentin at the front of an occlusal caries lesion where translucent dentin is detected by SM would result in deeper dentin demineralization measured from microradiography compared to the depth of dentin demineralization measured from SM.…”

Accuracy of visual and image-based ICDAS criteria compared with a micro-CT gold standard for caries detection on occlusal surfaces

“…9 Some advantages of the micro-CT method is that it is non-destructive and provides mineral density values as outcomes of caries presence instead of possibly relying on dentin reactions to caries rather than on the effect of tissue demineralization. 10 Moreover, micro-CT allows threedimensional visualization and quantification of sound and diseased tissues. 14 In the reconstruction phase of the present study, tissue demineralization was precisely obtained with the use of dipotassium hydrogen phosphate (K 2 PO 4 ) phantoms to calibrate micro-CT values against hydroxyapatite mineral density values.…”

Secondary caries and microleakage

“…Appraisal of the optical birefringence of dental tissues in PLM is influenced by many known and probably unknown variables, including the strong effects of extraction of lipid and protein and likely other organic substances on optical birefringence [56]. One team of investigators have even questioned whether estimates of mineral content in dentin based on PLM have been correctly interpreted over the years [57].…”

“…Moreover, collagen, which is abundant in dentin also displays form birefringence [89]. It is not unlikely that any or all of these confounders will cause or influence optical birefringence in the interface between a restoration and tooth when ground sections are observed in a PLM [57].…”