Figure 2.

Principal component analysis of known and unknown metabolites that were differently expressed before and after treatment with arginine and fluoride. Treatment with (a) the arginine toothpaste (A), and (b) the fluoride toothpaste (F). CA, caries-active subjects; CF, caries-free subjects; PF, plaque from carious-lesion free tooth surfaces; PE, plaque from active, enamel carious lesion; PD, plaque from active, dentin caries lesions. Note that some metabolites may appear twice because of positive and negative ion analyses.