Candidate Phyla Radiation (CPR) are a recent bacterial subdivision ubiquitous in the healthy oral microbiota. This study aimed to explore the prevalence of Candidatus Saccharibacteria in two oral pathological states, searching for a potential association with the formation of dental calculus or caries. A second objective was to determine the prevalence of cariogenic bacteria, in particular that of Streptococcus spp. from the same specimens. For this purpose, samples of dental calculus and caries were analysed using real time PCR to detect the presence and the abundance of the Candidatus Saccharibacteria and Streptococcus. spp. in these two oral pathologies. Based on real-time PCR results we show that Candidatus Saccharibacteria are more frequently detected (100% versus 78.8%, p =0.007), and more abundant (mean Ct=18.80 and 28.1, respectively, p<0.0001) in dental calculus compared to dental caries. Similarly, Streptococcus spp. were more prevalent (81% versus 28.6%, P-value =0.0006) and more abundant (mean Ct=24.5 versus 29.3, respectively, p<0.0001) in dental calculus than in caries From a microbiological point of view, our study suggest that there locally is no inverse relationship between the two pathologies. Analysis of saliva specimens could help to assess the impact of TM7 with oral diseases.