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[ original article ] In vitro determination of direct antimicrobial effect of calcium hydroxide associated with different substances against Enterococcus faecalis strainsAll strains had been frozen at -20 o C and were isolatedin M-Enterococcus agar medium (Difco ® ). Strainswere then identified following a standard identificationroutine described by Koneman et al. 1Activation of the strains was carried out on M-Entorococcusagar plates (Difco ® ) in an oven set at 36 o C for18-24 hours. Subsequently, colonies were suspended inBHI broth (Oxoid ® ) until complete turbidity of the mediumwas observed.Antimicrobial substances testedAll bacterial substances tested in this study werebased on calcium hydroxide P.A. paste (Table 1).The pastes were prepared by mixing 2 grams ofpowder to 70 drops of each corresponding vehicle, resultingin a mixture with toothpaste-like consistency afterspatulation. For each material tested, approximately12 grams of calcium hydroxide paste were manipulated.Table 1. Pastes used in the experiment.Ca(OH) 2+ guaçatonga extract in propylene glycolCa(OH) 2+ 1% guaçatonga solution in propylene glycolCa(OH) 2+ pure propylene glycolAssessment of the antimicrobial activityThe inoculum suspensions in BHI broth (Oxoid ® ),were diluted in 5 ml sterile saline to reach turbidity correspondingto 1 McFarland standard (3x10 8 cells/ml).For the antimicrobial activity test, 1,200 paperpoints (Tanari ® , Tanariman Ltda), previously sterilizedby autoclaving, were immersed in the experimentalbacterial suspensions for 3 minutes in order to achievecontamination. Following that, the paper points wereaseptically removed from the bacterial suspension anddistributed on the surface of sterile Petri dishes. Thepaper points were then covered by the different pastesbeing evaluated. The Petri dishes were covered andkept in an oven at 37 o C.At 6, 24, 48, 72 hours, and at 7 days, the paper pointswere removed from direct contact with the pastes andplaced in test tubes containing 4 ml sterile LetheenBroth (Difco ® ). The broth was incubated at 37 o C for 48hours and visually assessed for macroscopic turbidity.An inoculum containing 0.1 ml of Letheen broth wastransferred to a test tube with 4 ml BHI broth that hadbeen incubated under the same conditions. The BHI brothtest tubes with no evidence of turbidity were consideredas negative, and the ones displaying turbidity of the brothwere seeded on M-Enterococcus agar in order to determinewhether the bacterial strains remained viable.All the experimental procedures were conductedunder aseptic conditions with the aid of a laminar flowhood, and assays were performed in duplicate. One experimentwas carried out with a standard Enterococcusfaecalis ATCC 29212 strain.The pH of each paste was measured after manipulationand placement in deionized water, with the aidof a pH meter.ResultsThe pH values for the pastes were: 12.67 for the calciumhydroxide + 1% chlorhexidine, 12.62 for the calciumhydroxide + propylene glycol, and 12.60 for thecalcium hydroxide + Casearia sylvestris Sw extract.The assessment of antimicrobial activity for the threedifferent pastes at 6, 24, 48, 72 hours, and at 7 days postincubationshowed that all strains were inhibited in allperiods of evaluation (Table 2).DiscussonThe efficacy of Ca(OH) 2paste against E. faecalis andother microorganisms has been extensively discussed inthe scientific literature. 15-19The addition of chlorhexidine has conferred greaterantimicrobial efficacy to calcium hydroxide pastes usedfor disinfection of the dentin tubules. 7 However, Schäferet al 17 observed no increase in efficacy against E. faecalisby associating Ca(OH) 2with chlorexidine.Ercan et al, 18 in an in vitro experiment involving extractedteeth, revealed that 2% chlorhexidine gel was more efficientagainst E. faecalis and Candida albicans comparedto plain Ca(OH) 2or to Ca(OH) 2with 2% chlorexidine.Enterococcus faecalis needs to be maintained in directcontact with calcium hydroxide in order to be killed 20,21 .In the present work, the least amount of time Enterococcusfaecalis was kept in contact with the pastes was 6hours, and none of the strains survived.The results reported in this study for calcium hydroxidepaste with chlorhexidine are in agreement withEstrela et al, 21 who used similar methodology.© 2011 Dental Press Endodontics 48Dental Press Endod. 2011 apr-june;1(1):46-51
Weckwerth PH, Siquinelli NB, Weckwerth ACVB, Vivan RR, Duarte MAHTable 2. Antimicrobial action of the calcium hydroxide pastes against the different bacterial strains.Ca(OH) 2+ Propylene glycol Ca(OH) 2+ 1% Chlorexidine Ca(OH) 2+ Guaçatonga extract6h 24h 48h 72h 7d 6h 24h 48h 72h 7d 6h 24h 48h 72h 7d1 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -5 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -6 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -7 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -9 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -11 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -12 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -13 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -14 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -15 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -16 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -17 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -18 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -19 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -20 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -21 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -22 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -23 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -24 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -25 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -26 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -27 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -28 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -29 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -30 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -31 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -32 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -33 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -34 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -35 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -36 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -37 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -38 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -39 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -40 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -The antimicrobial action of calcium hydroxidearises from the release of hydroxyl ions with consequentpH increase, reaching 11 to 12.5. 22 Accordingto Siqueira-Júnior et al 23 the lethal effect of hydroxylions against bacterial cells is mainly due to the damageinflicted on their cytoplasmic membrane, proteindenaturation, and direct damage to DNA, althoughit is now clear that one of the crucial factors forE. faecalis survival in high pH is the presence of aproton pump that enables cytoplasmic homeostasis,even in extremely alkaline environments. 7 Enterococcusfaecalis strains have been found to survive in environmentswith pH as high as 10.5 to 11.0; pH valueshave to be greater than 11.5 in order to kill thesestrains. 24 In the present paper, all the pastes had pHgreater than 12.5 and were able to kill all strains.© 2011 Dental Press Endodontics 49Dental Press Endod. 2011 apr-june;1(1):46-51
Page 5 and 6: editorialRevolution in scientific i
Page 7: 64. Location of the apical foramen
Page 16 and 17: Endo in EndoOrthodontic treatment d
Page 18 and 19: [ endo in endo ]Orthodontic treatme
Page 24 and 25: [ original article ] A NiTi rotary
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Page 60 and 61: original articleRoot canal filling
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Page 66 and 67: original articleLocation of the api
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Page 90 and 91: [ case report ] Influence of cone b
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