Effect of three nickel-titanium rotary file techniques on infected root dentin reduction

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This study compared the bacterial reduction of in vitro infected root canals after instrumentation by 3 nickel-titanium (NiTi) rotary files with different taper and diameter versus manual stainless steel files.

Study design

Sixty-four single-rooted human teeth were infected with a suspension of Streptococcus sanguis measured by optical density. Teeth were divided randomly into 4 groups of 16 and prepared with Flexofiles, GT rotary files, HERO 642, and ProFile. Bacterial samplings were performed before (S1), during (S2-S3), and after (S4) instrumentation.


All techniques significantly reduced the number of bacterial cells in the root canals (P < .05). There was no significant difference between NiTi and manual instrumentation at S2, S3, or S4. Concerning bacterial reduction, the results suggest that a manual stainless steel file preparation is as efficient as a NiTi rotary instrumentation.


Regardless of the root canal preparation technique, its taper, and diameter, the root dentin remained infected and was not bacteria-free at the end of the experiment.

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