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Biology of Pulpal and Periradicular Tissues

OR23 - The Clinical Efficacy of Endodontic Procedures to Remove the Primary Endodontic Infection: An In-Vivo Study

Wednesday, April 2, 2025
3:00 PM – 3:15 PM EST
Location: Hynes Convention Center, Floor 3, Room 309

    Presenter(s)

  • AC

    Annie Chen, D.D.S.

    Resident
    University of Minnesota School of Dentistry
    Minneapolis, Minnesota

    Disclosure information not submitted.

    • Co-Author(s)

  • Ronald Ordinola Zapata, D.D.S., M.S., Ph.D.

    Associate Professor
    University of Minnesota School of Dentistry
    Roseville, Minnesota

    Disclosure(s): No financial relationships to disclose

Disclosure(s):
Ronald Ordinola Zapata, D.D.S., M.S., Ph.D.: No financial relationships to disclose
Objectives: To analyze microbial reduction and diversity changes following cleaning and shaping procedures, and calcium hydroxide interappointment medication.

Methods: Sixteen teeth diagnosed with pulp necrosis and apical periodontitis were selected. Five samples were collected on each tooth: A surface sample before pulp chamber access (C1), pulp space before treatment (S1), after cleaning and shaping (S2), at the second visit after removal of the temporary restoration (C2), and after removal of interappointment medication Ca(OH)2 (S3). Samples were processed using quantitative real-time polymerase chain reaction (qPCR) and 16S rRNA next-generation sequencing to measure microbial diversity. The Shannon and Chao1 indices were used to measure alpha diversity. Differences in abundance of genera were evaluated using the Kruskal-Wallis test. Differences in community composition (beta diversity) were evaluated using analysis of similarity (ANOSIM) with Bray-Curtis dissimilarity matrices.

Results: The analysis with qPCR showed significant differences between S1 and S2 (p=0.0001) as well as between S1 and S3 (p=0.0001). No significant differences between S2 and S3 were observed (p=0.458). A significant difference in the number of OTUS and Chao1 values between treatment methods (S1 vs S3) was observed. ANOSIM values revealed differences between S1 and S3 (p < 0.001, r=0.53), between S1 and S2 (p < 0.001, r=0.26), as well as between S2 and S3 (p=0.025, r=0.07).

Conclusion: qPCR analysis revealed a statistically significant reduction in microbial load after instrumentation (S2) and after calcium hydroxide medication (S3). The effect on root canal composition (beta diversity) was more marked after the use of calcium hydroxide.