The Oral Bacterial Microbiome of Interdental Surfaces in Adolescents According to Carious Risk

Abstract

Adolescence is closely associated with a high risk of caries. The identification of specific bacteria in an oral microniche, the interdental space of the molars, according to carious risk can facilitate the prediction of future caries and the anticipation of the progression or stabilization of caries in adolescents. A cross-sectional clinical study according to the bacteriological criteria of interdental healthy adolescents and carious risk factors-low and high-using a real-time polymerase chain reaction technique was conducted. The presence of 26 oral pathogens from the interdental microbiota of 50 adolescents aged 15 to 17 years were qualitatively and quantitatively analyzed. Bacteria known to be cariogenic (Bifidobacterium dentium, Lactobacillus spp., Rothia dentocariosa, Streptococcus cristatus, Streptococcus mutans, Streptococcus salivarius, Streptococcus sobrinus, and Streptococcus wiggsiae) did not present differences in abundance according to carious risk. Periodontal bacteria from the red complex are positively correlated with carious risk. However, only 3 bacteria-S. sobrinus, E corrodens and T. forsythia-presented a significant increase in the highest group. Estimating the risk of caries associated with bacterial factors in interdental sites of molars in adolescents contributes to the better definition of carious risk status, periodicity and intensity of diagnostic, prevention and restorative services.

Keywords: adolescents; carious risk; interdental microbiota; oral microbiome.

Figure 1

Workflow of the experiment. BOIB: Bleeding on Interdental Brushing; DNA: Deoxyribonucleic acid; ICDAS: International Caries Detection and Assessment System; PCR: Polymerase Chain Reaction.

Figure 2

Abundance of bacterial species among the interdental sites in the low carious risk and high carious risk groups. The counts are reported on a log10 scale. Each box represents the first quartile, median quartile, and third quartile, from bottom to top. The first box on the left (TB) corresponds to the total bacteria. The colors in boxes refer to (i) the colors of the Socransky complexes for the purple, green, yellow, orange, and red colors, (ii) cariogenic bacteria for the pink color and (iii) bacteria from the clostridium group for the gray color. TB, total bacterial load.

Figure 3

Abundance of bacterial species according to sex and interdental diameter in the low carious risk group and in the high carious risk group. The counts are reported on a log10 scale. Total counts from each pathogen were averaged across sites in each subgroup. Error bars represent standard deviations. This stratified analysis is restricted to those situations where the interaction between caries risk and sex (A) or caries risk and IDB size (B) on bacterial counts is significant (p < 0.05) (detailed results not shown). Comparisons: * p < 0.05, by using SUDAAN 7.0 (procedures DESCRIPT and REGRESS) to account for clustering (multiple sites within the subjects). The colors in boxes refer to (i) the colors of the Socransky complexes for the purple, green, yellow, orange, and red colors, (ii) cariogenic bacteria for the pink color and (iii) bacteria from the clostridium group for the gray color. TB: total bacterial load.

Figure 4

Correlation plot of the abundances of the bacterial species, corrected for age, interdental space and individual-specific effects. (A) High caries risk group, (B) low caries risk group. Yellow indicates positive correlations, whereas red indicates the absence of correlations. The colored leaves on the top dendrogram represent (i) the colors of the Socransky complexes for the purple, green, yellow, orange, and red colors, (ii) cariogenic bacteria for the pink color and (iii) bacteria from the clostridium group for the gray color.