Sixty-eight standardized human root specimens were infected with Enterococcus faecalis for 3 wk after removal of the smear layer. After 3 wk of infection, the smear layer was reformed and in half of the specimens, the smear layer was again removed. Aqueous Ca(OH)2 paste and silicone oil based Ca(OH)2 paste were used as the test medications. The specimens were divided into four groups (i.e. (a) nonsmeared aqueous calcium hydroxide group, (b) nonsmeared silicon oil-based calcium hydroxide group, (c) smeared aqueous calcium hydroxide group, and (d) smeared silicon oil-based calcium hydroxide group. Medications were placed in the canals for 7 days. After removal of medications dentin chips were collected and incubated. The quantity of bacteria present was assessed. All calcium hydroxide pastes were effective in the elimination of bacteria in the dentinal tubules, except in the smeared group with silicone oil-based calcium hydroxide.