Date of Graduation
School of Dentistry
John G. Thomas.
An important goal of root canal therapy is elimination of microorganisms which are usually organized into a biofilm phenotype. Irrigants play an indispensable role in areas inaccessible to mechanical instrumentation. In this study, a novel endodontic irrigant was formulated composed of a penetrating solvent, 70% Dimethyl sulfoxide (DMSO), with a 1:1 molar ratio of an antibiotic (Clindamycin HCl) and antifungal agent (Nystatin). Nuclear Magnetic Resonance Spectroscopy (NMR) stability tests were conducted to prove the mixture was chemically stable. This study compared different concentrations of the novel irrigant to 6% sodium hypochlorite (NaOCl) using a C. albicans biofilm model. Furthermore, it is proposed that the novel irrigant has the ability to penetrate into dentin tubules and therefore be able to achieve better root canal disinfection.;Solutions of the irrigant were prepared and used at 100%, 50%, and 25% concentration then compared to 6% NaOCl in the following tests: ZOI, CFU, absorbance, coverage area, and penetration. Standard zones of inhibition (ZOI) trials were conducted to verify that the novel irrigant was, in fact, effective against microorganisms. C. albicans, a common oral fungi, and possible co-aggregate in biofilm formation, was then grown on hydroxyapatite-coated pegs (Calgary Biofilm Model) for 48 hours at 37° C and immersed in treatment solutions for one minute. Biofilm was removed from the pegs via sonication and colony forming units per ml were assayed. On additional pegs, biofilm was stained with crystal violet, washed, placed in glacial acetic acid and read at 562nm; the absorbance values reflected the amount of remaining biofilm. On other pegs the remaining biofilm was stained and analyzed with computer software to determine the coverage area. Lastly, ten extracted human teeth were prepared, sterilized, and irrigated using 6% NaOCl, Ethylenediaminetetraacetic acid (EDTA), and the novel irrigant at 100%, 50%, and 25% concentration. The teeth were then stained with Rhodamine B and viewed at 10X with a laser confocal microscope to evaluate penetration.;The ZOI studies showed that the novel irrigant possessed effective anti-microbial properties. The CFU assay positive control showed 2.9X106 CFUs, the irrigant concentrations from greatest to least had the following CFUs respectively: 8.7X103, 2.7X104, and 6.7X10 3. No CFUs were observed with NaOCl; corresponding absorbance data revealed the following: 0.786, 0.830, 0.818 compared to a control value of 0.765. NaOCl had an absorbance of 0.843. These numbers suggest similar activity against a recalcitrant C. albicans biofilm. The biofilm coverage assay showed that the novel irrigant was more effective than 6% NaOCl. By utilizing the laser confocal microscope the ability of the novel irrigant to penetrate into dentin tubules was visualized.;Preliminary results using a C. albicans biofilm model show that all concentrations of the novel irrigant are anti-biofilm and demonstrate similar efficacy to that of 6% NaOCl. Furthermore, the novel irrigant is able to penetrate further into dentinal tubules than that of 6% NaOCl and EDTA or some combination of the two.
Reynolds, Dustin S., "Formulation and Evaluation of a Novel Irrigant for the Disinfection of Root Canals Using a Candida albicans Biofilm Model" (2013). Graduate Theses, Dissertations, and Problem Reports. 3622.