Schuweiler, David2025-01-282025-01-282022-08https://hdl.handle.net/11299/269511University of Minnesota M.S. thesis. August 2022. Major: Dentistry. Advisor: Ronald Ordinola Zapata. 1 computer file (PDF); vii, 46 pages.PURPOSE: The aim of this study was to characterize the microbiome of primary endodontic infections using 16S ribosomal RNA next-generation sequencing (NGS) technology and evaluate for differences among various demographic and radiographic factors. MATERIALS AND METHODS: 71 human participants with primary endodontic infections were evaluated for percussion tenderness, sinus tract presence, active caries, gender, probing depth >4mm, and age. Pre-operative radiographic lesion size was assessed with periapical index (PAI) as either PAI ≤ 2 (n = 12) or PAI = 5 (n = 19). Samples from the root canal were obtained and subsequent microbiome data was constructed. Differences in abundance of genera were evaluated using the Kruskal-Wallis test. Alpha and beta- diversity indices were calculated using Mothur. The Shannon and Chao1 indices were used to measure alpha diversity. Differences in community composition were evaluated using analysis of similarity (ANOSIM) with Bonferroni correction for multiple comparisons. RESULTS: No significant differences in microbiome relative to clinical factors were observed. A significant difference in beta-diversity was noted between PAI 2 and 5. Larger radiographic lesions demonstrated significant increase in Oribacterium, Phocaeicola, Lachnospiraceae uncl, Prevotellaceae, Selenomonadaceae uncl., Treponema, and Olsenella. CONCLUSION: No correlations were found between the microbial composition and the studied clinical factors associated with apical periodontitis. Differences in community composition were found in teeth with large radiolucencies.enThesis or Dissertation