Recognition of community profiles in endodontic infections may allow a better understanding of the pathogenesis of the disease and the establishment of more effective treatment protocols.

Therefore, the aim of the present study was to investigate bacterial diversity in endodontically infected primary and permanent teeth using 16S rRNA gene sequencing and QIIME 2TM (Quantitative Insights Into Microbial Ecology 2) bioinformatics pipeline

Endodontic infections are defined as an infection of the pulp and periapical tissues. This infection is caused by microorganisms that invade the pulp via dental caries or dental trauma. In these mixed population infections, anaerobic bacteria have been reported to be conspicuously dominant and the number of microorganisms per canal may vary. Traditionally, the endodontic microbiome has been identified by culture-based (phenotype-based) techniques. Inability to cultivate approximately 40-55% of bacteria in the endodontic microbiome, bias or inexperience of researchers may limit the results of cultural research. Microbiome-based new generation sequencing (NGS), which was initially used in ecological studies, has been widely used in recent years to identify bacterial diversity using the 16S ribosomal RNA (rRNA) gene in endodontic infections microbiome, bias or inexperience of researchers may limit the results of cultural research. There are few studies investigating the endodontic microbiome in primary teeth. However, to the best of our knowledge, to date, there is no metagenomic study that investigates the endodontic microbiome of the primary and permanent teeth. It is a still question of whether there is a difference in the endodontic microbiomes during the mixed dentition period when both dentition types can be seen.

Inclusion Criteria:

• have intact roots or <1/3 of physiological root resorption
• have clinical crowns that permit effective rubber dam isolation
• no mobility, fistula, pus discharge, gingival swelling, periapical abscess or internal resorption.

Exclusion Criteria:

• have marginal periodontitis, a history of pharmacological treatment, antibiotics or fluoride intake within the last 2 months
• a history of cancer, diabetes or immunodeficiency disorders