***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Aim : To evaluate and compare the pH and antibacterial property of Ca(OH)2 combined with iodine potassium iodide ( IKI ) or chlorhexidine ( CHX ) on E. faecalis and to assess and compare their effect on fracture resistance of root dentin . Material s and Methods : CHX ( 0.5 % ) The following test material s were used : Group I Calcium hydroxide + saline , Group II Calcium hydroxide + CHX ( 0.5 % ) and Group III Calcium hydroxide + IKI ( 2 % ) . For antibacterial activity , 60 root dentin blocks ( 20 in each group ) were infected by E. faecalis followed by placement of medicaments . At the end of 24 h and 7 days , 10 sample s from each group were r and omly chosen and assessed for antibacterial activity . For evaluation of root strength , 30 teeth were used and stored in sterile saline after placement of medicament . At the end of 30 days , sample s were subjected to fracture resistance testing on the Universal Strength Testing Machine . Hounsfield strength testing machine , UK pH of the various calcium hydroxide combinations was determined with a digital pH meter . Statistical analysis : Kruskal Wallis test , Mann Whitney U test , and one-way ANOVA test for intergroup comparison and Wilcoxon 's signed rank test and student 's paired t test for intragroup comparison . Results : Group III showed significantly greater antibacterial activity against E. faecalis , followed by group II and control group . There was no statistically significant change in the pH and root strength values among all the groups . Conclusion : The present study revealed that IKI or CHX in combination with Ca(OH)2 is an effective medicament against E. faecalis Contamination of the root canal system by persistent , enteric bacteria via leakage through interim restorations has been well documented . This in vitro study evaluated the ability of interappointment medications to prevent contamination of the root canal system by Enterococcus faecalis . Coronally unsealed , medicated tooth roots fixed in a closed system were contaminated daily with a st and ardized , aerobic , broth culture of E. faecalis . Four medications were evaluated ( n = 15 ) : group A , calcium hydroxide/methylcellulose paste ; group B , camphorated parachlorophenol/calcium hydroxide paste ; group C , 1 % chlorhexidine/methylcellulose gel ; and group D , calcium hydroxide points . The mean number of days to contamination as indicated by turbidity in the closed system was the following : group A , 37 ; group B , 46 ; group C , 16 ; group D , 5 ; and a positive control ( no medication ) , 3 . A one-way analysis of variance with a Scheffe post hoc test ( p = 0.05 ) detected significant differences in effectiveness with A and B superior to C and D , and C superior to OBJECTIVE The aim of this in vitro study was to assess the substantive antimicrobial activity of different medicaments in human root dentin . STUDY DESIGN Canals of 98 roots were enlarged to st and ard size and medicated for 7 days with the following : ( 1 ) 2 % chlorhexidine ( CHX ) gel , ( 2 ) 0.2 % CHX gel , ( 3 ) 2 % CHX solution , ( 4 ) Ca(OH)(2 ) , ( 5 ) Ca(OH)(2)+ 0.2 % CHX gel , ( 6 ) 2 % CHX solution + a 25 % CHX-containing controlled-release device , ( 7 ) saline , and ( 8) gel vehicle . After medication , canals were inoculated with Enterococcus faecalis for 21 days . Dentin sample s were collected with Gates-Glidden burs into brain heart infusion broth , and bacterial growth was assessed with spectrophotometric analysis of optical density after 72 hours of incubation . RESULTS Mean optical densities were significantly lower for groups with 2 % CHX ( 1 , 3 , and 6 ) when compared with those of the controls ( P < .05 , analysis of variance with the Tukey test ) . Other groups did not differ significantly from the controls . CONCLUSIONS Canal dressing for 1 week with 2 % CHX may provide residual antimicrobial activity against E faecalis Previous studies have demonstrated antimicrobial substantivity in root canal dentin up to 7 days after treatment with chlorhexidine . This in vitro study assessed the antimicrobial substantivity of chlorhexidine-treated  bovine root dentin over a period of 21 days . Sixty st and ardized bovine root sections were r and omly divided into three equal groups , and their canals immersed in one of the following solutions : ( i ) sterile saline ; ( ii ) 2.5 % NaOCl ; or ( iii ) 0.2 % chlorhexidine ( CHX ) . Half the specimens in each group were treated with the solution for 5 min and the other half for 7 days . After solutions were removed , the specimens were incubated at 37 degrees C in Brain Heart Infusion broth containing Enterococcus faecalis ( ATCC 29212 ) . A fresh inoculum was added to the broth every other day over a 21-day period . The canals were then enlarged with sterile burs , and the dentin shavings collected and cultured for the presence of cultivable bacteria in the dentinal tubules . Specimens treated with CHX for 7 days demonstrated significantly less dentin colonization by E. faecalis than the other specimens . CHX has potential as an intracanal medicament , if it can be applied for a period of at least 7 days AIM To determine the viability of Enterococcus faecalis in infected human root dentine in vitro after exposure to root canal medicaments based on chlorhexidine and octenidine . METHODOLOGY Human root segments ( n = 40 ) were infected with E. faecalis for 8 weeks . Root dentine sample s ( rd ) collected at week 4 served as individual baseline values . At week 8 , the root segments were r and omly divided into four test groups ( n = 10 each ) for the placement of one of the following medicaments in the root canals : calcium hydroxide paste ( CH ) , chlorhexidine gel ( CHX-gel ) ( 5.0 % ) , chlorhexidine/gutta-percha points ( CHX-GP ) ( active points ( ® ) ; Roeko , Langenau , Germany ) and octenidine gel ( OCT-gel ) ( 5.0 % ) followed by incubation for 4 weeks . The effect on E. faecalis viability was assessed by two fluorescent dyes ( syto 9/propidium iodide ) to determine the ' proportion of viable bacteria ' ( PVB% ) and number of ' colony-forming units ' ( CFU ) . Mean values and 95 % confidence intervals ( CI ) were calculated for PVB% and log CFU , and the difference between groups was established . RESULTS Viable and dead bacterial cells were detected in all ' rd ' sample s at weeks 4 and 8 . The treatment with CHX-gel , CHX-GP and OCT-gel result ed in significantly lower PVB% values with 15.4 % , 3.5 % and 0 % , respectively . No growth ( CFU ) was recorded for these sample s at week 12 . When medicated by CH , the PVB% was increased without a corresponding change in CFUs . CONCLUSIONS In contrast to calcium hydroxide , both CHX - and octenidine-based intracanal medicaments were effective in decreasing the viability of E. faecalis . OCT showed the most favourable results and may have potential as an endodontic medicament 
    Output:
    
According to the evidence available now , mixing CH with CHX does not significantly increase the antimicrobial activity of CH against E. faecalis .
It appears that mixing CH with CHX does not improve its ex vivo antibacterial property as an intracanal medicament against E. faecalis .