Comparison of the Bacterial Composition and Structure in Symptomatic and Asymptomatic Endodontic Infections Associated with Root-Filled Teeth Using Pyrosequencing

Abstract

Residual microorganisms and/or re-infections are a major cause for root canal therapy failure. Understanding of the bacterial content could improve treatment protocols. Fifty samples from 25 symptomatic and 25 asymptomatic previously root-filled teeth were collected from Sudanese patients with periradicular lesions. Amplified 16S rRNA gene (V1-V2) variable regions were subjected to pyrosequencing (FLX 454) to determine the bacterial profile. Obtained quality-controlled sequences from forty samples were classified into 741 operational taxonomic units (OTUs) at 3% dissimilarity, 525 at 5% dissimilarity and 297 at 10% dissimilarity, approximately corresponding to species-, genus- and class levels. The most abundant phyla were: Firmicutes (29.9%), Proteobacteria (26.1%), Actinobacteria (22.72%), Bacteroidetes (13.31%) and Fusobacteria (4.55%). Symptomatic patients had more Firmicutes and Fusobacteria than asymptomatic patients, while asymptomatic patients showed more Proteobacteria and Actinobacteria. Interaction of disease status and age was observed by two-way ANOSIM. Canonical correspondence analysis for age, tooth restoration and disease status showed a correlation of disease status with the composition and prevalence of different members of the microbial community. The pyrosequencing analysis revealed a distinctly higher diversity of the microbiota compared to earlier reports. The comparison of symptomatic and asymptomatic patients showed a clear association of the composition of the bacterial community with the presence and absence of symptoms in conjunction with the patients’ age.

Comparison of Bacterial Community Composition of Primary and Persistent Endodontic Infections Using Pyrosequencing

“…The technology enables a large number of reads in a single run, providing increased sampling depth compared to other techniques (7) and has the major advantage of enabling the detection of low-abundant genera (7,8). So far, only eight studies have used this approach to investigate different types of endodontic infections (7,9–15). From those, only two investigations have examined the endodontic microbiome in teeth with failed endodontic treatment (14,15).…”

“…So far, only eight studies have used this approach to investigate different types of endodontic infections (7,9–15). From those, only two investigations have examined the endodontic microbiome in teeth with failed endodontic treatment (14,15). Even though these persistent infections present an important clinical problem, there is a knowledge gap in their microbial etiology, especially regarding the low-abundant bacteria.…”

Pathogenic Bacterial Species Associated with Endodontic Infection Evade Innate Immune Control by Disabling Neutrophils

“…Another recent sequencing-based study identified Prevotella species in 91 to 94% of patients (52). In many studies, Prevotella species are the first or second most frequently identified species (4,52). These observations can be explained by our discovery of a cytotoxic activity associated with P. intermedia.…”

“…While endodontic infections are invariably polymicrobial, Prevotella species are strongly associated with both primary endodontic and periapical infections (4,52). In one study of endodontic infections of deciduous teeth, P. intermedia was the most frequently identified species out of 83 taxa assessed: overall, 96.5% of the 40 samples tested contained P. intermedia (53).…”

“…In one study of endodontic infections of deciduous teeth, P. intermedia was the most frequently identified species out of 83 taxa assessed: overall, 96.5% of the 40 samples tested contained P. intermedia (53). Another recent sequencing-based study identified Prevotella species in 91 to 94% of patients (52). In many studies, Prevotella species are the first or second most frequently identified species (4,52).…”