The residual antibacterial effects of radiopaque double antibiotic paste after various treatment times

Indiana University-Purdue University Indianapolis (IUPUI)Introduction: Regenerative endodontic procedures require adequate disinfection of immature teeth with necrotic pulps. Regeneration endodontic procedures have been shown to increase width and length of dentin after disinfection of the root canal system with various antibiotic pastes such as double antibiotic paste (DAP). DAP is composed of an equal ratio of metronidazole and ciprofloxacin. After the root canal system is disinfected with DAP, it is later flushed out with 17-percent EDTA. There is a need for a radiopaque component in the DAP to facilitate proper placement. Following disinfection with DAP, a residual antibacterial effect is formed in dentin. It is not known if this effect is modified by making DAP radiopaque. Objectives: The residual antibacterial effects of a radiopaque double antibiotic paste against a bacterial isolate obtained from an immature tooth with necrotic pulp on radicular dentin will be explored utilizing various strengths of DAP (1 mg/mL, 10 mg/mL, and 25 mg/mL) after 1 week and 4 weeks. Materials and Methods: Dentin samples of 4x4-mm will be prepared from previously extracted human posterior teeth. The samples will be assigned to seven treatment groups in a random fashion (G1 will be treated with 25-, G2-10, and G3-1 mg/mL of radiopaque DAP. G4 will be treated with the radiopaque filler without DAP. G5 will be treated with Ca(OH)2 and G6 sterile water with bacterial biofilm, and G7 will be sterile water). The groups will be treated for both 1 week 4 weeks. These samples will then be stored in a phosphate buffered saline (PBS) solution for 1 week and then inoculated with the cultured bacterial isolate from an immature tooth with necrotic pulp. The specimens will be incubated for three weeks to permit adequate formation of a biofilm. The biofilm will be detached, diluted and spirally plated onto blood agar plates and incubated for a total of 48 hours in 5-percent CO2 at 37°C. The number of CFUs/mL will be counted using an automated colony counter. A two way ANOVA and Fisher’s Protected Least Significant Differences test using 5-percent significance level will be used to evaluate the resulting data. Expected outcome: A residual antibacterial effect will be observed on radicular dentin samples when treated with radiopaque DAP. Conclusion: Using a radiopaque DAP that provides residual antibacterial effects, further awareness into regenerative endodontic procedures will be gained leading to alterations in treating such cases.2020-06-3