Correlation between number of viable S. mutans cells detected by culture and number detected by PMA-qPCR and/or conventional qPCR. (A and B) Dental plaque from caries-free patients (n=24). (B) Carious dentin from patients with dental caries (n=21). All data were calculated three times for CFU, PMA-qPCR, and qPCR, and the mean values were plotted. X = log10x, where x is the cell number calculated by PMA-qPCR (A and C) or qPCR (B and D). Y = log10y, where y is CFU.