IADR Abstract Archives
Non-Mutans Low-pH Streptococci Do Not Precede a Cariogenic Plaque Microbiota
Objectives: To determine if non-mutans low-pH streptococci are present in high proportions in dental plaque prior to the acquisition of a cariogenic plaque microbiota and diagnosis of caries.
Methods: Children of 1 to 3 years of age, with no history of dental caries, were followed for 18 months with pooled plaque samples obtained at baseline and 6-month intervals. Forty random colonies were selected from Selective Strep Agar plates for each visit and assayed for the terminal pH after overnight incubation in Chemically Defined Medium (CDM), and CDM with 0.1% arginine. Low pH streptococci were defined as those with a terminal pH ≤ to the S. mutans control plus 0.12. Strains capable of metabolizing arginine were defined as those with a terminal pH ≥ to the S. sanguinis control minus 0.09. Numbers of low-pH streptococci and arginine metabolizers were compared between caries-free and caries subjects, as were the averages of terminal pH for all isolates combined. Microbiome and mycobiome analyses were also completed.
Results: 18 of 130 children developed dental caries (ICDAS score > 0) during their time in the study. When age and gender matched to 18 children who remained caries-free, there was no evidence of high proportions of non-mutans low pH streptococci in advance of detectable levels of S. mutans. In fact, the opposite trend was observed. Permutation t-tests of Area Under the Curve (AUC) for the interval preceding and up to the time of caries diagnosis found a statistically significant association with the recovery of S. mutans as well as the average terminal pH readings in CDM and CDM plus arginine.
Conclusions: Non-mutans low-pH streptococci do not appear to set the stage for the acquisition of a cariogenic dysbiotic plaque microbiota. Caries diagnoses were preceded by an elevation of overall acidogenicity and/or decreased representation of arginine metabolizers.
Methods: Children of 1 to 3 years of age, with no history of dental caries, were followed for 18 months with pooled plaque samples obtained at baseline and 6-month intervals. Forty random colonies were selected from Selective Strep Agar plates for each visit and assayed for the terminal pH after overnight incubation in Chemically Defined Medium (CDM), and CDM with 0.1% arginine. Low pH streptococci were defined as those with a terminal pH ≤ to the S. mutans control plus 0.12. Strains capable of metabolizing arginine were defined as those with a terminal pH ≥ to the S. sanguinis control minus 0.09. Numbers of low-pH streptococci and arginine metabolizers were compared between caries-free and caries subjects, as were the averages of terminal pH for all isolates combined. Microbiome and mycobiome analyses were also completed.
Results: 18 of 130 children developed dental caries (ICDAS score > 0) during their time in the study. When age and gender matched to 18 children who remained caries-free, there was no evidence of high proportions of non-mutans low pH streptococci in advance of detectable levels of S. mutans. In fact, the opposite trend was observed. Permutation t-tests of Area Under the Curve (AUC) for the interval preceding and up to the time of caries diagnosis found a statistically significant association with the recovery of S. mutans as well as the average terminal pH readings in CDM and CDM plus arginine.
Conclusions: Non-mutans low-pH streptococci do not appear to set the stage for the acquisition of a cariogenic dysbiotic plaque microbiota. Caries diagnoses were preceded by an elevation of overall acidogenicity and/or decreased representation of arginine metabolizers.