Bacterial 16S Sequence Analysis of Severe Caries in Young Permanent Teeth

Abstract

Previous studies have confirmed the association of the acid producers Streptococcus mutans and Lactobacillus spp. with childhood caries, but they also suggested these microorganisms are not sufficient to explain all cases of caries. In addition, health-associated bacterial community profiles are not well understood, including the importance of base production and acid catabolism in pH homeostasis. The bacterial community composition in health and in severe caries of the young permanent dentition was compared using Sanger sequencing of the ribosomal 16S rRNA genes. Lactobacillus species were dominant in severe caries, and levels rose significantly as caries progressed from initial to deep lesions. S. mutans was often observed at high levels in the early stages of caries but also in some healthy subjects and was not statistically significantly associated with caries progression in the overall model. Lactobacillus or S. mutans was found either at low levels or not present in several samples. Other potential acid producers observed at high levels in these subjects included strains of Selenomonas, Neisseria, and Streptococcus mitis. Propionibacterium FMA5 was significantly associated with caries progression but was not found at high levels. An overall loss of community diversity occurred as caries progressed, and species that significantly decreased included the Streptococcus mitis-S. pneumoniae-S. infantis group, Corynebacterium matruchotii, Streptococcus gordonii, Streptococcus cristatus, Capnocytophaga gingivalis, Eubacterium IR009, Campylobacter rectus, and Lachnospiraceae sp. C1. The relationship of acid-base metabolism to 16S rRNA gene-based species assignments appears to be complex, and metagenomic approaches that would allow functional profiling of entire genomes will be helpful in elucidating the microbial pathogenesis of caries.Dental caries is the most common chronic disease of childhood, affecting nearly three-fourths of all children by the age of 17 years (50). The majority of children experience mild caries in the permanent dentition that is easily managed, but nearly 20% of children suffer more aggressive caries (19) that is destructive and often recurrent. The cariogenicity of Streptococcus mutans and Lactobacillus species in tooth-associated biofilms has long been established based on culture studies (51), but this approach has provided a limited ability to study the role of other species present in biofilm communities. Recently DNA-based methods have been used to study early childhood caries (5, 11, 23), caries of the primary and permanent teeth in children and young adults (1), root caries in the elderly (42), and advanced dentin lesions (8,10,36). Taken together these studies have confirmed the association of S. mutans and Lactobacillus species with childhood caries, but they also suggest that these species are not sufficient to explain all cases of caries. In addition, health-associated bacterial community profiles are not well understood, including the importance of species that produce basic co...

Acid-resistant genes of oral plaque microbiome from the functional metagenomics

“…Further, expression of the gene in question and successful translation may not be efficient in the E. coli host since some gram-positive proteins are toxic when translated within E. coli . An alternative explanation might be the limitations of the samples and method: (i) Studies have confirmed that S. mutans is not the only predominant caries-pathogenic bacterium [14,15]; depending on individual patients, it might not be the principal ECC bacterium [42]. Hence, in this study, the abundance of S. mutans might only occupy a small fraction of the collected caries samples, limiting the genetic information in our library and reducing the chance of obtaining functional genes.…”

“…Recent high-throughput sequencing studies based on culture-independent analysis of childhood caries revealed that S. mutans is not the only dominant pathogenic bacterium in caries. Lactobacillus, Selenomonas and Neisseria can also be detected at high levels in severe carious plaques [14,15], and some of these bacteria cannot be cultured (Human Oral Microbiome Database (HOMD), http://www.homd.org/). In addition to Streptococcus , our knowledge about the acid resistance and related regulatory genes of cariogenic microorganisms, especially those that are not cultivable, is limited; thus, it offers a fertile field for the current study.…”

Cariogenic microflora and pH in superficial and deep layers of occlusal carious lesions - A metagenomic analysis

“…[14] Recent molecular study using second-generation sequencing and metagenomic techniques has discovered an extraordinary ecosystem where S. mutans accounted for only 0.7-1.6% of carious lesions. [10,33] However, some recent studies indicate that the relationship between S. mutans, and caries is not absolute high proportions of S. mutans may persist on tooth surfaces without lesion development, and caries can develop in the complete absence of S. mutans. [34,35] Veillonella are an acidogenic Firmicutes with 5.8% of the total population.…”

“…This includes S. mutans, non-mutans Streptococci and members of the genera Actinomyces, Bifidobacterium, L.bacillus, Propionibacterium, Veillonella, Selenomonas, and Atopobium are associated with different stages of carious lesions. [7][8][9][10] Low environmental pH was due to shift of an acid-tolerant and acid-producing consortium of bacteria, which altered the balance of remineralization to demineralization, thus forming the carious lesions. [11] The size and thickness of the lesion was also correlated with the initial pH.…”

Evaluation of cariogenic antibacterial activity of mineral trioxide aggregate and Portland cement

“…However, no previous studies have evaluated the antimicrobial activity exclusively against bacterial strains of deep decayed dentin [16][17] .…”