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.