The dental plaque microbiome in health and disease

Abstract

Dental decay is one of the most prevalent chronic diseases worldwide. A variety of factors, including microbial, genetic, immunological, behavioral and environmental, interact to contribute to dental caries onset and development. Previous studies focused on the microbial basis for dental caries have identified species associated with both dental health and disease. The purpose of the current study was to improve our knowledge of the microbial species involved in dental caries and health by performing a comprehensive 16S rDNA profiling of the dental plaque microbiome of both caries-free and caries-active subjects. Analysis of over 50,000 nearly full-length 16S rDNA clones allowed the identification of 1,372 operational taxonomic units (OTUs) in the dental plaque microbiome. Approximately half of the OTUs were common to both caries-free and caries-active microbiomes and present at similar abundance. The majority of differences in OTU's reflected very low abundance phylotypes. This survey allowed us to define the population structure of the dental plaque microbiome and to identify the microbial signatures associated with dental health and disease. The deep profiling of dental plaque allowed the identification of 87 phylotypes that are over-represented in either caries-free or caries-active subjects. Among these signatures, those associated with dental health outnumbered those associated with dental caries by nearly two-fold. A comparison of this data to other published studies indicate significant heterogeneity in study outcomes and suggest that novel approaches may be required to further define the signatures of dental caries onset and progression.

Figure 1. Caries Phenotype Determination.

Quantitative Light fluorescence (QLF) of occlusal surfaces of C-F and C-A subjects. Quantitative light fluorescence (QLF) examination was conducted to complement clinical examinations and the DIFOTI procedure. C-A subjects had an average of 12 (range = 6–17) decayed tooth surfaces whereas C-F subjects presented with a decay component = 0. Subjects had an average of 11.5 decayed surfaces and 2.3 restored surfaces. These individuals presented with primary dentition only. C-A subjects had an average of 74 healthy surfaces.

Figure 2. Differential Representation of Genera in the C-F and C-A Microbiomes.

Bars to the left correspond to over-representation of genera in the C-F subject pool, and bars to the right correspond to over-representation in the C-A subject pool. Bar color key references percentage of the total 16S sequences.

Figure 3. Statistical Significance of Differential Species Abundance Between the C-F and C-A Microbiomes.

Volcano plot depicting the relationship between –log p-values resulting from standard binomial tests of frequency differences between C-A and C-F for each phylotype identified as a function of the standardized difference in phylotype frequency between C-A and C-F.

Figure 4. Comparison of C-F and C-A Species Abundance.

The 16 most abundant species and their relative abundance in C-F and C-A subject pools.