Methods: Thirty six mandibular premolars were decoronated, and the root length was standardized. All specimens were randomly distributed into the following three groups:

Group I (control): 2% LA mixed with sterile water.

Group II: 2% LA with 3% NaOCL,

Group III: 2% LA with 3% CHX. In all groups mechanical instrumentation with rotary files was done. Teeth samples were sectioned into three parts, split and SEM analysis of root canal wall was done at cervical. Middle, and apical root thirds.

Results: SEM images revealed patent dentinal tubules with no precipitate occlusion in group I and group III, whereas there was occlusion of dentinal tubules with a precipitate in group II at all the three root levels studied.

Conclusions: The precipitate formed on the interaction between 2% LA solution with 3% NaOCL tends to occlude the dentinal tubules at the coronal, middle, and apical root thirds. The chemomechanical rotary instrumentation procedure did not effectively remove the precipitate from all the three root levels of the specimens studied. LA/sterile water group and LA/CHX group did not result in any precipitate formation on root canal dentin.