Abstract
Apical periodontitis caused by microbial infection in the dental pulp is characterized by inflammation, destruction of the pulpal and periradicular tissues, and alveolar bone resorption. We analyzed the chronological changes in microbiota using a pyrosequencing-based approach combined with radiologic and histopathologic changes in a rat apical periodontitis model. During the three-week observation, the pulp and periapical area showed a typical progress of apical periodontitis. A total of 27 phyla, 645 genera, and 1276 species were identified. The root apex had a lower bacterial species diversity than the pulp chamber. Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria were dominant phyla in both the pulp chamber and root apex. Remarkably, bacterial communities showed a tendency to change in the root apex based on the disease progression. At the genus level, Escherichia, Streptococcus, Lactobacillus, Rodentibacter, and Bacteroidetes were dominant genera in the pulp chamber. The most abundant genera in the root apex were Bradyrhizobium, Halomonas, and Escherichia. The species Azospirillum oryzae increased in the pulp chamber, whereas the species Bradyrhizobium japonicum and Halomonas stevensii were highly observed in the root apex as the disease progressed. The experimental rat model of apical periodontitis demonstrated a relationship between the microbiota and the apical periodontitis progression.
Highlights
Apical periodontitis is an inflammatory disease of the periradicular tissues caused by bacterial infections in the dental pulp system, mostly due to caries, defective restorations, trauma, or failure of root canal treatment [1,2]
The present study mainly aimed to investigate the chronological changes in the endodontic microbiota in a rat model with progression in apical periodontitis
In the radiologic and histologic analyses of this study, we found that simple pulp exposure could lead to rapid progress of pulpal necrosis, immune cell infiltration throughout the pulp and periapical lesion, and alveolar bone resorption in the periradicular area through three weeks, which is consistent with previous studies [3,26,27,28]
Summary
Apical periodontitis is an inflammatory disease of the periradicular tissues caused by bacterial infections in the dental pulp system, mostly due to caries, defective restorations, trauma, or failure of root canal treatment [1,2]. The development of sequencing tools has resulted in increased insight into the bacterial diversity of the infected root canal system. Next-generation sequencing using a pyrosequencing method has efficiently and accurately identified even a minor population of bacterial species, thereby offering deep insight into apical periodontitis [8,9]. Most pyrosequencing studies for apical periodontitis have collected human endodontic infection samples and compared high-throughput microbiota under variable conditions, such as acute versus chronic [10], primary versus persistent infections [11], and symptomatic versus asymptomatic infections [12]
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