Determination of Caries Lesion Activity: Reflection and Roughness for Characterization of Caries Progression

Caries lesion progression is difficult to determine with visual and tactile examinations. The hypothesis of this study was that reflection and roughness measurements could determine caries progression. Ground/polished sound human enamel specimens were analyzed at baseline (sound) and after two four-day demineralization periods for reflection using optical reflectometry (ORef) and for roughness using optical surface profilometry (SPro). Specimens were demineralized using a microbial- Streptococcus mutans aries model. Comparisons among the periods for ORef and SPro were performed using repeated measures analysis of variance. Two-sample t-tests were used for differences in transverse microradiography. The integrated mineral loss and depth of the four-day demineralization period were significantly smaller than those for the eight-day demineralization period ( p<0.01). With increased demineralization time, reflection was significantly decreased and roughness was significantly increased ( p<0.01). Correlation between ORef and SPro was moderate ( r=-0.63). Both reflection and roughness can be characterized for nondestructive longitudinal assessment of caries lesion progression.