Detection of potentially cariogenic strains of Streptococcus mutans using the polymerase chain reaction

Streptococcus mutans is a pathogen related to the occurrence of human dental caries. The determina-tion of total amounts of mutans streptococci, as well as the proportion related to other oral bacteria, is of interest when assessing the risk of developing caries. In this context, it is better to use a sensitive, spe-cific and non-time consuming method such as the polymerase chain reaction (PCR), than to use cul-ture and biochemical identification methods. In this work we identified potentially cariogenic strains of S. mutans and assessed the relationship with the dmft, DMFT or dmft/DMFT index. Using DNA isolated from dental plaque, a 192 bp sequence was identified and amplified from the spaP gene and a 722 bp sequence from the dexA gene. The results suggest that it is important to evaluate the presence of cariogenic S. mutans strains in plaque content rather than the accumulation of plaque itself. How-ever, other factors like diet, hygiene, genetic background, the flow rate of saliva and the presence of spe-cific antibodies, also play a key role in the development of caries.

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