asathickopaque,usuallyyellowishtogreenliquidthatisformedbyexudate,leuc - PDF document

asathickopaque,usuallyyellowishtogreenliquidthatisformedbyexudate,leucocytes,variousbacterialspecies,deadcellsandtissuedebris(Dorland1994).Italsocontainsvariousbacterialspecies,mostofwhichareanaerobic(Siqueiraetal.Thehydrogenionconcentrationinbloodplasmaandvariousbodysolutionsisamongstthemostintensivelyregulatedvariablesinhumanphysiology.Attheintercellularmembranelevel,theregulationofpHisessentialtocontrolthemetabolismandßuxesoftheionizedformsofweakacidsandbases(Schwiening&Willoughby2000).Thelong-termstabilityofbloodpHisachievedbyremovingtheacidasrapidlyaspossible(Clancy&McVicar2007a).Withinclinicaldentistry,thepHoftissueshasanumberofimplications.ThepHoflocalanaestheticsolutionandthetissuesintowhichitisinjectedhasaneffectonitsnerveblockingaction(Malmed2004).AcidiÞcationofthetissuesasaresultofinßammatoryproductsisbelievedtodecreasetheeffectivenessoflocalanaesthetics(Tsuchiyaetal.2007).Theincreasedhydrogenionconcentrationresultsinagreaterpropor-tionoftheanaestheticagentexistinginitscationicform,ratherthaninitsbasicform.Thisshiftinequilibriummeansthattheanaestheticmaybelessabletodiffusethroughinfectedtissuesthanthroughnormaltissues,leadingtodelayedonsetandloweredintensityofanaesthesia(Ondriasetal.1987,Malmed2004).Furthermore,alowpHenvironmentmayaffectdentalmaterials(Royetal.2001,Francisconietal.2008).Forexample,Silvaetal.(2007)reportedinalaboratorystudythatanacidicenvironmentalteredthesurfacecharacteristicsandmicrohardnessofglassionomercements.Torabinejadetal.(1995)suggestedthatanacidicpHmayimpedethesettingprocessofMineralTrioxideAggregate(MTA).Thus,variationsinthepHofhosttissues,becauseofpre-existingdiseaseatthetimeofMTAplacement,couldaffectitsphysicalandchemicalproperties(Leeetal.2004,Namazikhahetal.VariousinvestigationshavesuggestedthatthepHofaninfectedtissueandofpusislikelytobelowerthanthatofhealthytissue(Malmed2004,Tsuchiyaetal.2007).However,surprisingly,thereislimitedclinicalinformationonthepHofpus.TheaimofthisstudywastodeterminethepHofpusdrainedfromperiapicalabscessesinhumans.MaterialsandmethodsPatientswererecruitedfromtheOralandMaxillofacialSurgeryclinicattheShariatihospitalinTehran,Iran.Alldocumentationandprocedureswereapprovedbytheethicalboardofthelocalresearchreviewcommit-tee,intheFacultyofDentistry,TehranUniversityofMedicalSciences,Iran.Subjectswhovolunteeredweregivenadescriptionoftheprojectandinformedconsentwasobtained.Fortypatients(17maleand23female)withanacuteperiapicalabscessandassociatedswell-ingwereincluded.Allparticipantshadmoderate-to-severepainonpercussionaccompaniedbylocalizedintraoralorgeneralizedfacialswelling.Theywereinotherwisegoodgeneralhealth,whichwasassessedinareviewoftheirmedicalhistory.Tominimizeobserverbias,onlyoneclinicianexam-inedthepatients.Oncethediagnosisofanacuteabscesswasmade,atleast1mLofpuswasaspiratedusingasterilesyringewithaNo20gaugeneedlefromeachsubjectunderstrictinfectioncontrolprocedures.Toeliminateanyconfoundingeffect,localanaestheticsolutionwasnotusedpriortoaspiration.IfthepussamplewasmLorwascontaminatedwithblood,itwasexcludedfromthestudy.AnUltraBasicPortablepHmeter(DenverInstrument,Denver,CO,USA)wasimmediatelyusedtomeasurethepH.ThepHmeterelectrodewasinsertedintothecontainerthatcarriedthepussampleandavalueforpHwasobtained.Aftereverymeasurement,theelectrodewasplacedintheneutralizingsolutionsuppliedbythemanufac-turertocalibrateittothepHof7.IndependentandSpearmanÕsrankcorrelationcoefÞcientswereemployedtoinvestigatetherelationshipbetweenpHandageandgender.TheresultsaresummarizedinTable1.Overall,40participants(17maleand23female)wereincluded.ThemeanpHmeasurementwas6.68(SD=0.324).ThepHrangedfrom6to7.3.ThemeanpHinmalepatientswas6.7(SD0.382),whilstinfemalepatients, Table1pHofpusaspiratedfromperiapicalabscessesMaleFemaleOverallNumber172340Meanage272526MeanpH6.706.666.68Standarddeviation0.30820.35880.3345RangepH6.0–7.36.0–7.26.0–7.3pH7.00131730pH=7.00325pH&#x-335;&#x.600;7.00145 Nekoofaretal.pHofperiapicalabscessInternationalEndodonticJournalInternationalEndodonticJournal,534–538,2009 itwas6.66(SD=0.358);genderdidnothaveasigniÞcanteffectonpH(=0.750).Theageofparticipantsrangedbetween17and35years;themeanagewas26.22(SD=4.26).TherewasnostatisticallysigniÞcantcorrelationbetweenageandpH.In1893,duringhisstudiesonphagocytosis,Metch-nikoffrevealedthatthepHinsidephagocyteswasacidic.Heconcludedthatthisacidicenvironmentwithinthecellcouldresultinthedestructionofingestedorganisms(Gourkoetal.2000).Duringphagocytosis,polymorphoneuclear(PMN)leucocytesdegranulateandreleaseenzymes,whichareactivatedinanacidicpH.Inalaboratorystudy,Jensen&Bainton(1973)investigatedpHchangesduringphagocytosisanddemonstratedthatthepHofaphagosomewasreducedtoapproximately6.5within3Ð4minafterinitiationofphagocytosis.Theyreportedthatafter7Ð15min,thepHdroppedto3.5Ð4.5andremainedwithinthisrangeforupto2h.AsthepHfalls,leucocytesmayexhibitcellinjuryandconsequentlydie,aphenomenonthatresultsinpusformation.Therefore,itisgenerallybelievedthatinßamedand/orinfectedtissueshavealowpH(Malmed2004,Tsu-etal.2007).Accordingly,thepresenceofcertainacidssuchasisobutyric,butyric,isovaleric,valeric,isocaproicandcaproicacidcanbeidentiÞedbygaschromatography(Tanakaetal.1990)andactasindicatorsofanaerobicbacterialinfection(Kalowskietal.1992).Inaddition,theproductionoflacticandaceticacid,asaresultofglucosemetabolismbybacteria,maydecreasepHlevels(Halletal.However,acidsoutsidethephagosomesarequicklyneutralizedbythephysiologicalregulatorymecha-nisms.Inaninterventionalstudy,McCormicketal.(1983)introducedStreptococcusfaecalisinto24imma-turepremolarteethofsixyoungbeagledogs.TheinitialpHrangeofthedevelopingperiapicallesionsfellfrom7.1Ð7.2to6.2Ð6.6respectively.Furthermore,theyreportedthatthepHoftheperiapicallesionschangedwithtimebackto7.0Ð7.2irrespectiveofthetypeoftreatmentprovided.Wieseetal.(1999)studiedthepathophysiologyofodontogenicabscessesandidenti-ÞedthepHvalueofpustobe6.164±0.233,whichisinaccordancewiththatreportedbyMcCormicketal.(1983)andtheÞndingsofthepresentstudy.Indeed,inthepresentstudy,themeanpHofpusaspiratedfromperiapicalabscesseswas6.68±0.324suggestingthatthephysiologicalregulatorymechanismsareactiveintissuestonormalizethebloodandtissuepHinhealthanddisease.Thesecomplexphysiologicalregulatorymechanismscanbecategorizedasshort-term,inter-mediateandlong-termhomeostasis(Clancy&McVicar2007a,b).Theintermediateandlong-termstabilityofthepHofbloodisachievedbyremovingtheacidasrapidlyaspossiblethroughtherespiratoryandrenalsystemsrespectively(Clancy&McVicar2007a).Theshort-termregulationofacidseemstobemorecomplex(Messeter&Siesjo1971).Whentheinternalbodyisexposedtoasubstantialamountofacid,severalrapidmechanismsbecomeactivetouptakethehydrogenionssuchaschangesincarbondioxidetension,relativeelectrolytecon-centrationsandtotalweakacidconcentration.Inadditiontothis,physicochemicalbuffering,cellularconsumptionofnonvolatileacidsandtransferofacidoralkalibetweenthecytosolandorganellesactastheshort-termregulatorymechanisms(Messeter&Siesjo1971,Kellum2000,2005,Clancy&McVicarAcidicpHmayhaveadverseeffectsonprovidingadequatelocalanaesthesia(Wong&Jacobsen1992,Malmed2004).However,thereareanumberofotherreasonsthatcanexplainthefailureoflocalanaestheticincludinganatomical,pharmacological,psychologicalandpathologicalfactors.AcidicpHasaresultofpathologicalnaturemaydecreasetheconcentrationoftheunionizedfractionoflocalanaesthetic,thatis,thelipophilicproportionofthelocalanaestheticthatdiffusesthroughthenervesheaths(Meechan1999).TheefÞcacyoflocalanaestheticsolutionsdependslargelyontheconcentrationofthislipophilicfractionetal.1987).ThepotentialacidicpHofperiapicalabscessescannotalwaysexplainthefailureoflocalanaesthesia(Wong&Jacobsen1992,Meechan1999).Indeed,theresultsofthepresentstudyrevealedthatthepHofaspiratedpusfromperiapicalabscesseswasnotalwaysacidic,buthadarangebetween6and7.3(mean=6.68,SD=0.3345).Inaddition,duringaregionalnerveblock,localanaestheticsolutionsmaybedepositedatasitedistantfrominßammation(Madanetal.2002).Inthissituation,nervehyperalgesiaand/oranincreasedbloodsupplytotheinßamedareamayexplaintheanaestheticfailure(Meechan1999).UtilizingacombinationofregionalnerveblockandlocalinÞltrationinjectionsand/ortheadministrationofsupplementarytechniquessuchasintraosseousandintraligamentaryinjectionsmayovercomethefailureoflocalanaesthesia(Madanetal.Meechan2002,Malmed2004).Theuseofahigher pHofperiapicalabscessNekoofaretal.InternationalEndodonticJournal,534–538,2009InternationalEndodonticJournal concentrationoflocalanaestheticisalsosuggested(Meechan1999).AcidicpHmayalsohaveaneffectonthepropertiesofdentalmaterials,whichareroutinelyplacedinenvironmentsthatmaybeinßamedorinfected.Inalaboratorystudy,Namazikhahetal.(2008)showedthatdetrimentaleffectsonsurfacemicrohardnessofMineralTrioxideAggregateoccurredatpH4.4.ThemeanVickerssurfacemicrohardnessvalueatthispHwas14.34comparedto53.19observedwhenthematerialwasexposedtopH7.4.AtpH6.4,themeanVickerssurfacemicrohardnessvaluewas40.73.OnthebasisoftheirÞndingsandtheresultsofthepresentstudy,themeanpHofpus(6.68)wouldposeminimaleffectsonsurfacemicrohardnessofMTA.etal.(2004)comparedthesurfacemicrohard-nessandhydrationbehaviourofMTAsamplesundervariousphysiologicalenvironments.TheyfoundthatsampleshydratedatapHof5,hadsurfacemicrohard-nessvaluesthatweresigniÞcantlylowercomparedwithdistilledwater,normalsalineandasolutionbufferedatpH7.Inaddition,theyshowedthatthemeanmicrohardnessofthegrouphydratedatpH7wassigniÞcantlygreaterthanthathydratedindistilledwater,suggestingthebeneÞcialeffectofthispH.Royetal.(2001)evaluatedtheeffectofacidicpHonthemicroleakageofvariousroot-endÞllingmaterialsincludingamalgam,Geristore,Super-EBA,MTA,Cal-ciumPhosphateCement(CPC)orMTAwithCPCmatrix.TheyreportedthatatpH5,nostatisticallysigniÞcantdifferenceexistedbetweenthematerialsexceptforamalgam.VariousconcentrationandtypesofacidmayhavedissimilareffectsonthephysicalandchemicalcharacteristicsofPortlandcements(Taylor1997)andasMTAisaPortlandcement-likematerialetal.2006),itmightalsobeaffected.Singhetal.(1986)revealedthatlacticacidacceleratedthehydrationofPortlandcementbyincreasingthecrys-tallinecharacterofcalciumhydroxideresultinginadvancedgrowthofthehydrationproducts.Incon-trast,Raietal.(2006)reportedthatinthepresenceoftartaricacid,thesilicatehydration-phaseofPortlandcementwasretardedstrongly.Inthepresentstudy,thepHofpusasanindicatorofacidconcentrationwasmeasured.Furtheranalysisofpusand/orinßamedtissuetodeterminepresenceandconcentrationsofvariousacidsandtheevaluationoftheeffectofdifferenttypesofacidonvariousdentalmaterialsissuggested.etal.(2007)evaluatedinalaboratorystudy,theeffectofacidicpH(6.2Ð4.3)onßuoridereleaseandthesurfacemicrohardnessoftwotypesofpolyacid-modiÞedresincompositesandthreetypesofglassionomercements;surfacecharacteristicswerealsoobserved.TheyreportedthatßuoridereleasewasincreasedasaresultofaloweracidicpHonbothmaterials,buttherewasnostatisticallysigniÞcanteffectofanacidicpHonthesurfacemicrohardnessofpolyacid-modiÞedresincomposites.However,atlowpHvalues,asigniÞcantchangeinthesurfacemicrohardnessofglassionomercementswasobserved.AccordingtotheresultsofthepresentstudythatshowedthepHrangeofaspiratedpusfromperiapicalabscessestobebetween6.00and7.3andtheÞndingsofSilvaetal.(2007),itcanbeconcludedthatthepHofpusinperiapicalabscesseswouldhaveonlyminimaleffectsonpolyacid-modiÞedresincompositesandglassionomercements.ThepHofpusaspiratedfromperiapicalabscesseswasacidic(6.68±0.324).TherewasnostatisticallysigniÞcantassociationbetweenpHandageorgender.Furtheranalysisofpustodeterminethepresenceandconcentrationsofvariousacidsissuggested.AsgaryS,ParirokhM,EghbalMJ,StoweS,BrinkF(2006)AqualitativeX-rayanalysisofwhiteandgreymineraltrioxideaggregateusingcompositionalimaging.JournalofMaterialsScience:MaterialsinMedicine,187Ð91.CichaI,SuzukiY,TateishiN,MaedaN(2003)ChangesofRBCaggregationinoxygenationÐdeoxygenation:pHdependencyandcellmorphology.AmericanJournalofPhysiology-HeartandCirculatoryPhysiology,2335Ð42.ClancyJ,McVicarA(2007a)Intermediateandlong-termregulationofacid-basehomeostasis.BritishJournalofNursing,1076Ð9.ClancyJ,McVicarA(2007b)Short-termregulationofacid-basehomeostasisofbodyßuids.BritishJournalofNursing,1016Ð21.DorlandWA(1994)Dorland’sIllustratedMedicalDictionaryPhiladelphia,PA,USA:W.B.SaundersCompany.FrancisconiLF,HonorioHM,RiosD,MagalhaesAC,MachadoMA,BuzalafMA(2008)EffectoferosivepHcyclingondifferentrestorativematerialsandonenamelrestoredwiththesematerials.OperativeDentistry,203Ð8.GeisowMJ(1981)Temporalchangesoflysosomeandphago-somepHduringphagolysosomeformationinmacrophages:studiesbyßuorescencespectroscopy.TheJournalofCell,645Ð52.GourkoH,WilliamsonDI,TauberAI(2000)TheEvolutionaryBiologyPapersofElieMetchnikoff.London:KluwerAcademicPublishers. 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