sobrinus using S. sobrinus-free saliva and S. sobrinus-free dental plaque as an alternative in the spiking experiment. As shown in Figure 3, neither saliva nor dental plaque inhibited the PCR, indicating that this assay is applicable

for measuring cariogenic bacteria in oral specimens. We next examined the correlation between the numbers of viable S. mutans cells in oral specimens as detected by PMA-qPCR and by culture. We found a positive correlation between these quantification methods for both carious dentin and dental plaque. Compared with culture, the number of viable S. mutans cells was overestimated by PMA-qPCR. It may be that the culture method GSK1120212 research buy usually underestimates the cell number. The cell number determined by conventional qPCR correlated with the cell number determined by culture. Several previous investigations have reported that the cell number determined by qPCR correlated with CFU [14, 15]. However, compared with PMA-qPCR, conventional qPCR overestimated the cell number to a greater extent in both types of clinical specimens. Therefore, the cell culture

count was closer to the number determined by PMA-qPCR than to that determined by conventional qPCR in the present study. Monitoring viable bacterial cells in oral specimens provides information to help understand oral infectious diseases. When we compared the total and viable cell numbers in carious dentin from patients with dental caries and dental plaque from caries-free children, there was no significant difference Selinexor purchase between carious dentin and dental plaque in terms of either total number S. mutans cells or number of viable cells. We may not be able to simply compare the cell numbers in these specimens because the contents are not identical. Nevertheless, there was no significant difference in the percentage of viable cells between the specimens. However, there was a significant difference in total cell number and viable cell number between saliva from patients with dental caries and saliva from caries-free children. Monitoring of the viable cell number in relation to the total cell number in oral specimens has not previously

been performed. To understand the variation in the viable cell number, both the viable and total cell numbers must be determined. To further understand Protein kinase N1 cell viability in relation to dental caries, a greater number of specimens should be analyzed. When the relationship between the number of viable S. mutans cells in saliva and in dental plaque from caries-free children was analyzed using PMA-qPCR, a positive correlation was found between viable S. mutans cells in saliva and in dental plaque. This result was consistent with previous reports [16]. There was no significant correlation between the number of viable S. mutans cells in saliva and that in carious dentin from caries patients in the present study. Our data suggest that saliva reflects the number of viable cells in caries-free plaque, but not in carious dentin.