OR10 - In-Vitro Comparison of the Antimicrobial Activity of Intracanal Medicaments on Mature Multispecies Biofilm

Abstract:
The purpose of this study was to test the antimicrobial activity of intracanal medicaments calcium hydroxide (CH), double antibiotic paste (DAP), and triple antibiotic paste (TAP) in a direct contact test utilizing Next Generation Sequencing (NGS). A mature 12-day multispecies biofilm developed on hydroxyapatite discs using a CDC reactor. Discs were treated with a direct contact test with no treatment (control), propylene glycol (PG), CH, DAP, and TAP (n=6 per treatment group). DNA extraction was completed immediately upon removal from the reactor for the control, while treatment samples were incubated anaerobically for 7 days prior to extraction. Samples were processed for analysis with real-time quantitative PCR (qPCR) and NGS. Samples with insufficient reads were excluded from NGS. Statistical analysis was completed using a significance level of 0.05, except where the Bonferroni correction was applicable. A mature multispecies biofilm was confirmed via SEM and sequencing. The CH groups had the lowest amount of mean reads and OTUs; however, due to significant DNA reduction in the CH group, NGS analysis could not be completed. TAP showed a significant difference in alpha (via Shannon Index) and beta-diversity compared to the control. The genera with the highest relative abundance across the groups were Parvimonas, Prevotella, Selenonadaceae spp., Oribacterium, and Campylobacter. Within the limitations of this study, CH was found to be the most effective in disinfecting a mature multispecies biofilm developed on hydroxyapatite discs in a direct contact test, and TAP was more effective than DAP.