Association between visual-tactile characteristics of root caries and histological severity

Methods:  One hundred extracted human teeth with visible root caries lesions were selected. Visual-tactile characteristics color, texture, and depth of surface loss were recorded for each lesion. The teeth were sectioned through the lesion with a hard-tissue microtome obtaining 2-3 samples per lesion. The samples were evaluated under Polarized Light Microscopy. The depth of the lesion was measured by image analysis software, drawing a line electronically to replicate the original shape and location of the cementum, and two landmarks to establish the depths of surface loss and demineralized dentin. The computer software calculated the perpendicular distance between the initial straight line and the landmarks in millimeters. A three-way fixed-effects ANOVA model with Tukey-Kramer multiple comparisons adjustment was used to evaluate the relationship between visual-tactile characteristics and histological evaluation. Two-sample t-tests were used to compare the groups defined by ICDAS with respect to histological measures.

Results:  Mean depth of demineralized dentin varied significantly with lesion texture (p=0.0455). Visual-tactile evaluations of depth of surface loss and color did not appear to be significantly related to the mean depth of demineralized dentin. The difference between ICDAS code 1 and 2 lesions was significant; code 2 lesions had a greater depth of demineralized dentin tubule involvement in the carious lesion (p<0.0001).

Conclusions: The visual-tactile characteristics texture and depth of surface loss were significantly associated with the histological depth of surface loss. Only texture was significantly associated with the histological depth of demineralized dentin. The findings of this in vitro study help validate the codes proposed by ICDAS for root caries classification.