The In Vitro Evaluation Of Different Calcium Hydroxide Pastes Against Enterococcus Faecalis In Root Canal

Objective: The aim of this study was to evaluate antimicrobial efficacy of the different calcium hydroxide pastes against Enterococcus faecalis, and then to give a reference to clinical application .Methods:Test one:pH Values of Calcium Hydroxide mixed by five different medicineThe saturated solutions of calcium hydroxide were prepared by adding- powder to the different medicine separately.The pH values of 5 saturated solutions were measured at 0,10,30,45 minutes,1,24,48 hours, and 7 days by a pH microelectrode.Test two:Antibiotic susceptibility testRound wells were punched in the agar plates and filled with one of the five different calcium hydroxide pastes.Each group was performed in six agar plates.The agar plates with the medicaments were incubated in an incubator(5% CO2) at 37℃for 48 hours. Then, the diameters of yeast inhibition zones around each well were measured.Test three:Root canal disinfection testFifty-six extracted, single-rooted mandibular first premolar were collected and divided randomly into five experimente groups ( physiolo- gical saline,sodium hypochlorite,camphorated phenol, glycerin, chlorhe- xidine) and two control groups (negative control).Each group had 8 speci- mens.All the specimens were infected with E.faecalis, except the negative control group. Then the canals of experiment groups were injected with the pastes untill full and incubated at 37℃(5% CO2),while the canals of positive control group were filled with physiological saline.After 3 and 7 days, dentin chips were collected and incubated in BHI for 72 hours to observe the growth of the microorganism by a spectrophotometer.Results:Test one: There were no statistically significant differences among mean pH values of 0,10,30,45minutes,1 hour in each group.The highest mean pH value was observed at day 7.When different vehicles were compared,the lowest pH value was observed in chlorhexidine.Th e mean pH value of sterile saline was the highest(P<0.05).Test two: Calcium hydroxide with camphorated phenol demonstrated larger inhibition zones than with chlorhexidine(P<0.05).Calciumhydroxide with chlorhexidine demonstrated the larger inhibition zones than with physiological saline,sodium hypochlorite and glycerin (P<0.05).There were no significant differences among the groups of calcium hydroxide with physiological saline,sodium hypochlorite and glycerin (P>0.05).Test three: The groups of calcium hydroxide with glycerin, cam- phorated phenol were better effective on eliminating the bacteria than with sodium hypochlorite, chlorhexidine and physiological saline when the pastes were placed for 3 days. All the medicaments were effective on eliminating the bacteria when the pastes were placed for 7 days, but calcium hydroxide mixed with camphorated phenol demonstrated the best anti- microbial activity.Conclusions: The groups of calcium hydroxide with camphorated phenol were better effective on eliminating the E.faecalis.It suggested that the calcium hydroxide pastes was last for 7 days.