The purposes of this study were firstly to investigate the any formation of precipitate after interaction between ALX and NaOCL and secondarily to analyze the PCA formation by using time of flight secondary ion mass (TOF-SIM) spectrometry. Mass spectrometry analysis was performed for the mixture of 0.5% ALX and 5.25% NaOCl. As controls, 2.5% CHX with 5.25% NaOCl and 1% PCA solutions were used. Any formation of precipitates in 10 tested solutions was evaluated by naked eye. Results of mass spectrum showed that the typical peak of PCA was not detected in mixed solution of ALX and NaOCl, whereas CHX/NaOCl mixture showed the same peak that found in the PCA spectrum. Precipitate formation was only observed in CHX/NaOCL mixture. The present TOF-SIM spectrometry results indicated that ALX can be a useful root canal irrigant combined with NaOCl during canal instrumentation. Further study is necessary to confirm the antimicrobial effect of ALX against endodontic pathogen before its clinical application as an endodontic irrigant.

The purpose of this study was to compare the different canal irrigation methods to prevent the formation of precipitate between sodium hypochlorite (NaOCl) and chlorhexidine (CHX).

Extracted 50 human single-rooted teeth were used. The root canals were instrumented using NiTi rotary file (Profile .04/#40) with 2.5% NaOCl and 17% EDTA as irrigants. Teeth were randomly divided into four experimental groups and one control group as follows; Control group: 2.5% NaOCl only, Group 1: 2.5% NaOCl + 2% CHX, Group 2: 2.5% NaOCl + paper points + 2% CHX, Group 3: 2.5% NaOCl + preparation with one large sized-file + 2% CHX, Group 4: 2.5% NaOCl +95% alcohol+ 2% CHX.

The teeth were split in bucco-lingual aspect and the specimens were observed using Field Emission Scanning Electron Microscope. The percentages of remaining debris and patent dentinal tubules were determined. Statistical analysis was performed with one-way analysis of variance (ANOVA). Energy Dispersive x-ray Spectroscopy was used for analyzing the occluded materials in dentinal tubule for elementary analysis.

There were no significant differences in percentage of remaining debris and patent tubules between all experimental groups at all levels (p > .05).

In elementary analysis, the most occluded materials in dentinal tubule were dentin debris. NaOCl/CHX precipitate was detected in one tooth specimen of Group 1.

In conclusion, there were no significant precipitate on root canal, but suspected material was detected on Group 1. The irrigation system used in this study could be prevent the precipitate formation.