Evaluation of a nonthermal plasma needle to eliminate <i>ex vivo</i> biofilms in root canals of extracted human teeth

Abstract

AIM: To evaluate the efficacy of a nonthermal plasma (NTP) at atmospheric pressure on ex vivo biofilm in root canals of extracted teeth. METHODOLOGY: Intracanal contents from three teeth with root canal infections were collected, pooled and grown in thirty-five microCT-mapped root canals of extracted and instrumented human teeth. One group of teeth was treated with NTP, another with 6% NaOCl and one set was left untreated. The intracanal contents from twenty-seven teeth (nine teeth in each group) were plated on agar and colony forming units were determined. Parametric test of one-way analysis of variance (anova) was used to analyse statistical significance. The remaining teeth were cut open, stained with LIVE/DEAD(®) and examined with confocal laser scanning microscopy. RESULTS: The untreated root canals were covered with biofilm of varying thickness. Treatment with nonthermal plasma decreased the number of viable bacteria in biofilms by one order of magnitude, whilst the NaOCl control achieved a reduction of more than four magnitudes. Both the NTP and the NaOCl treatment results were significantly different from the negative control (P < 0.05). CONCLUSION: The nonthermal plasma displayed antimicrobial activity against endodontic biofilms in root canals, but was not as effective as the use of 6% NaOCl.