專業(yè)英語 Unit 30教案.docx

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1、UnitThirty TheSurgicalPrinciplesofOsseointegration RagnarAdell Osseointegration;processanddefinition. Thepossibilityofpermanentlyretainingtitaniumfixtureinvitalremodelingbonewithacapacityofconsiderableloadbearingdependsonanadequatecomprehensionoftheosseointegrationprocess.ProfessorPcr-lngvarBran

2、emarkcoinedOsscointigrationasatermintheearly1970s.Itscurrentdefinition-adirectcontactbetweenliving,haversianboneandtheloadedimplantsurface-isbasedonhistologicalandultrastructuralobservationsbutisnotyetfullydefined. However,itiswellsupportedbylong-termradiographicandclinicalstudiesdemonstratingpcrif

3、ixturalboneadaptionandremodelingaswellaslong-termfixturestabilityandload-bearingcapacity. Thereisnoinstantosseointegration.Itsgradualandslowdevelopmentmustbefullyunderstoodinorderforasuccessfulclinicaloulcomelobeachieved. Achievingosseointegation Themereuseoftitaniumasanimplantmaterialisbynomeans

4、anyguaranteeofachievingosseointegration.Managingthehostorganismandtissuesshouldattractatleastasmuchinterestasthepropertiesandhandlingoftheimplant. Preoperativehostfactors Generalpatientconditions Noinvestigationssofarhavebeenundertakensystematicallytoevaluatetheinfluenceofdiseases,medications,and

5、drugsthatmaytheoreticallyaffectwoundhcaling-cspcciallybonehealingandremodeling-afterinstallationoftitaniumfixtures.Severalsuchpatientpreconditionscouldbeconsidered: 1. Age 2. Sex(duetopostmenopausalosteoporosis) 3. Malabsorptionsyndromes(eg,ulcerativecolitis)Bonemetabolicdiseases(eg,osteoporosis,

6、osteomalacia,gyperparathyroidism,Paget'sdisease) 4. Rheumaticdiseases(eg,rheumatoidarthritis,Sjogren'ssyndrome,systemiclupuserythematosus) 5. Hormonaldiseases(eg,diabetes,Cushing'ssyndrome,gyperparathyroidisrn) 6. Coagulationdisordersandanticoagulationmedications 7. Systemictreatmentwithglucocor

7、ticoidcs 8. Alcoholabuse 9. Tobaccosmoking Studieshaveinitiallyindicatedthatahigherchronologicalpatientagealoneisnotadeterminingfactorfortheoutcomeoftreatmentwithfixtures,whereastobaccosmokingmaybe.Sofar,thereisinsufficientevidencetosupporttheinstallationoffixturesingrowingjaws.Experimentalstudie

8、sandafewclinicaltrialsindicatethatthefixturesmaynotmovewith Losingmseointegration Aclinicallymobilefixture,beitduetoaneverestablishedoseointegrationorlatertototallylostosseointegration,hasneverbeenobservedtobecomestable/osseointegratedagain.Theonlyconditionthatmaymimictruemobilitywithafibroussleev

9、earoundthefixtureiswhenthesupportingboneismostlycancellousandnotyetsufficientlyremodeled.Aminuteelasticitymaythenbeexperiencedandpossiblymisinterpreted.Fixturessupportedinthismannerareofcourseatgreatriskandcould,moreover,transmitpressuretoadjacentnerves.Afewcasesofunpleasantsensationsfollowingloadin

10、gofsuchfixtureshavebeenaUributedtothesecircumstances. Apartiallossofosseointegration(ie,lossofmarginalbonesupport)isdifficulttohandleifitalsoentailsexposureofthreadstowardmobileoralmucosa.Grindingorfillingthethreadsisoflimitedornovalue.Thereisalwaysdifficultyinkeeping(hedepthofthethreadclosesttothe

11、bonemarginfreefrombacterialplaque.Infact,thissituationmaybetheonlyonethatcouldultimatelyrequireremovalofastablefixturebymeansofatrephinebur.Guidedtissueregenerationhasnotbeentestedforthisindicationandmaynotworkwellwhenthetitaniumsurfacehasalreadybeencontaminated.Thesameappliescorecoveringthefixturew

12、ithafreshperiostealflapwithorwithoutaninterposedbonegraft. TherecommendationsbyLckhomctalonhowtomanagemobilefixturesandotherclinicalsurgicalcomplicationsstillholdtrue. Maintainingosseointegration Twofactorsinfluencingthefixture-supportingbonemustbecontrolledfbr(helifespanofthefixture,namely,loadi

13、ngandtheperiabutmentconditions. Loading Asemphasizedearlierinthischapter,theperifixturalboneadaptstotheloadapplied.Itsfullstrengthisseldomreacheduntilafterayearofadequateload.Overloadingevenafterseveralyears(eg,bybruxism,changeoftheopposingbitetoporcelaincrowns,orbyachangeofextensionorfitofthesupr

14、astructurc)couldcauseperifixturalmicrofracturcs,whichthenmayhealwithnon-mineralizedconnectivescartissue.Asaresult,thefixtureswillbecomemobile.Ontheotherhand,ifadequatelyloaded,fixturesmaycontributetothepreservationofmandibularboneheight. Periabutmentandperifixturalconditions Anyinflammationinthepe

15、riabutmentsofttissuescausedbytraumaand/ormicrobiologicalagentscouldcausemarginalboneresorptionandshouldconsequentlybeavoided.Whenthemarginaloralsofttissuearchealthy,thereisonlyminutemarginalboneresorptionofapproximately1mmthroughthefirstyear,andthenonly0.1mmannuallyforthefollowingyears.Individualvar

16、iationscould,however,beconsiderableandtheirreasonsarenotwellknown.Thepreoperativehostfactorcouldinfluencethemarginalbonesupportandwellasthepostoperativeconditions.Forexample,whetherbasaljawboneforfixturesupporthasagreaterresistancetolossofmarginalboneheightthanthealveolarprocessproperhasnotbeeninves

17、tigated. Summary Whendueattentionispaidtotheindividualprcopcrativchostconditions,whentreatmentiscarriedoutwithprecisionaccordinglorecommendedguidelines,andwhentheabovefactorsformaintenancearecontrolled,anumberoflong-termstudiesonlargematerialsindicatethatosseointegrationoffixtures,onceestablished,

18、willbemaintainedfbrmanyyearswithapredictable,highdegreeofload-bearingcapacity. VOCABULARY 1.osseointegration 骨結(jié)合 2.Haversionbone 哈佛氏骨 3.instant 直接的，立刻的 4.tibia 腔骨 5.granuloma 肉芽腫 6.interferewith 干擾 7.inclination 傾斜 8.postmenopausal 絕經(jīng)后的 9.osteoporosis 骨質(zhì)疏松癥 10.colitis 結(jié)腸炎 11.o

19、steomalacia 骨軟化 12.Paget*sdisease 變形性骨炎 13.Lupuserythematosus 紅斑狼瘡 14.Cushing'ssyndrome 皮質(zhì)醇過多癥 increasingverticalheightofthejaw.Rheumatoidarthritisisnotregardedasacontraindicationfortheuseofosseointegratedimplantsinorthopedicsurgery. Amongthemorethan35,000patientstheworldoverwhohavebeentr

20、eatedwithimplantfixtures,anumberareknowntobemedicallycompromisedbyoneorseveralofthefactorslistedabovewithlittleornoinfluenceonthetreatmentoutcome.Thisespeciallyappliestopostmenopausalosteoporosis.Womenareveryproneto(hiscondition,butanumberofstudieshaveshownhighsuccessratesoftreatmentwithosseointegra

21、tedfixturesinwomenpatientsabove50yearsofage.Osteoporosisasapossibly13egativefactorwas,however,notseparatelyanalyzed.Anumberofnon-insulindependentdiabeticshavealsobeenincludedinthesematerialswithnoovertinfluenceontheoutcome. Localhosttissueconditions Localboneosteogenicandremodelingcapacityplusthei

22、ntegrityofthecoveringsofttissuesdeterminewhetherornotosseoinlegraiionwillresultafterfixtureinstallation,providedsurgeryisperformedstrictlyaccordingtobasicrecommendations.Itshouldbeemphasizedthatlocalhosttissueconditionscanvaryconsiderablyfromoneareatoanotherwithinthesamepatient. Onlyareascoveredbyi

23、ntactsofttissuesshouldbechosenfortheinstallationoffixtures.Consequently,allpossiblelesionsinskinormucosa(eg,eczema,candidasis,lichenplanus,leukoplakia,erosions)shouldfirstbetreatedbeforefixtureinstallationisattempted.Theinstallationoffixturesunderamucosalorsplitskingraftmustbeconsideredmoreriskythan

24、beneathanintactintegument.Suchgrafts'haveareducedresistancetomechanicalwear,andtheiroriginalplacementhasgenerallyimpliedandinterferencewiththebondsupplytotheperiosteum. Localbonequantityandqualityshouldideallybemadeupofawell-vascularized-bonearea,slightlylongerthanthefixtureandwithadiameternotlesst

25、han5mm(forastandard3.75mmdiameterfixture).Itisoftheutmostimportantthatthefixtureachievesinitialstability.Thisisbestbroughtaboutifitsmarginalandapicalpartsarcengagedincorticalbone.Anycancellousbonepresentshouldideallyhaveahighproportionofbonytrabeculaefurtherlosupportthefixture.Ilscancellouscompartme

26、ntsshouldcontainanosteopotenendosteumandmarrowtissue.Areaswithemptyorfattymarrowcompartmentsshouldbeavoided,asshouldsiteswithasmallratiooftrabeculatosofttissuemarrow. Possibleareaswith(heidealcharacteristicsmatchingthepositionsandinclinationsoffixturesasdesiredfortheplannedsuprastructureshouldbesou

27、ght.Intheclinicalsituation,oneorseveralofthefollowingcircumstancesmayinfluencetentativefixturesites. Localanatomy Notallareasinthemaxillofacialregionfulfilltheaboverequirements.Agoodexampleisupperversuslowerjawbone(Fig7-1).Thethinmaxillaryoutercompactlayerwillcontributelittletothestabilizationoffi

28、xtures.Initialimmobilizationcanthencomeonlyfromtheapicalendsbeingengagedinthecorticalnasalormaxillarysinusfloor.Maxillarytuberosityareasareverysoft,whereasthestructuralreinforcementsofthemidface-thecanine,zygomatic,andpterygoidareas-providebetterconditionsfortheinitialstabilizationoffixtures.Moreove

29、r,atriangularwidening,reinforcedbycorticalbone,canfrequentlybefoundclosetotheincisivecanaleveninseverelyresorbedcases.Thisareaisgenerallyagoodfixturesiteprovidedthemyelinsheathofthenerveisnotengaged.Ifthisoccurs,ossepintegralionwillnotensue. I Fig7-1Corticallinings,markedbyarrows,sutableforthea

30、nchorageoffixturestoprovideinitialstability,Corticalboneinthetemporalregionisnotmarked.Hatchedareasinthemidfaceindicatestructuralreinforcementsalsosuitableforfixtureplacement. Anteriormandibularbonebetweenthementalforaminagenerallyprovidesgoodopportunitiesforinitialstabilizationoffixturesbybicort

31、icalanchorageinmarginalandbasalbone.Posteriorlyinthemandible,theupperbordermarginalbonestaysverythinwhilethecancellousboneabovethemandibularcanalstaysverysoft.Thefrontalandzygomaticboneandthebonesofthecalvadaareallbicorticalandhence,inspiteof(heirlimitedthicknessofonlyafewmillimeters,providegoodinit

32、ialstabilization. DegreeofresorptionTheedentulousalveolarprocessispronetocontinuousresorption-adenture-relatedordis-useatrophy.Unduepressurefromaresidualpartialopposingbiteorill-fittingdenturesmayaggravatetheresorption. Severeresorptionofthemandiblegenerallyimpliesthattheresidualbasalboneismadeupo

33、fpoorlyvascularized,almostentirelycompactbone.Thereverseisalsotrue;thatis,aconsiderableresidualbonevolumeshouldraisedoubtsaboutthepossibilitiesforinitialsiabilizationoffixtures.Suchjawsfrequentlycontainanabundanceofverysoftcancellousbone. Thetopicandtechniquesofsimultaneousbonegraftingandfixtureins

34、tallationarecoveredinchaptersIO.I3,14,25,and26.Animportantquestionis,however,whentograftandwhennotto.Twoprinciplesshouldbeconsidered.Oneisthattheload-bearingcapacitydependsonthequalityoftheboneanditstotalinterfacesurfacewiththefixtures.Agreatnumberofevenshortfixturescanconsequentlytakeaconsiderablel

35、oadiftheboneisofgoodquality.Theotherprincipleisthattheresorptionofthejawbone,ifpossible,shouldnotbeallowedtoprogresstoofar,asfixturesanchoringabonegraftneedsomevolumeandstrengthof(preferablycortical)basalboneforthecrucialinitialstabilizationofthetransplant. Congenitaldefects Maxillaryboneadjacentt

36、ocleftsisfrequentlyparticularlysoftandoflimitedvolume.Areasofdentalaplasiaareoftencollapsedinthebuccolingualdirection;sufficientbonevolumeforfixtureplacementcanthenonlybefounddeepinthejaw. Surgicaltraumaandinterventionsforpathology Anybonesurgerystartsahealingandremodelingprocess.Theverygentlesurg

37、eryofafixtureinstallationisnoexception,evenifitsconsequencescanbeforeseentobemild.Althoughdesignedtobeaslittletraumatizingtothe(issuesaspossible,itwasshownintherapidlybonehealingrabbitthatthehealingoffixturesitesinthetibiarequiredaremodelingprocessofatleast1yearformostofthefixturethreadstobecomefill

38、edwithosseointegratingbone.Althoughnostudieshavebeenperformedsofar,itistemptingtoassumethattheslower-bone-healinghumanmayrequireamoreextendedperiodoftimefbrthesameresulttobebroughtabout.Ifthehealingiscompromisedbylessgentlesurgery,removalofintrabonyPathologicalprocesses(eg.cystsorteethwithperiapical

39、granulomas,and/orthetissuesarcleftforhealingbysecondaryintention),(heneteffectmaybehealingwithscarfibroustissueinsteadofbone. Itisnotuncommontofindonlyfibrousgranulation'tissuecentrallyinextractionsocketsthatearliercontainedteethaffectedbysevereperiodontitis,whichwereextractedbyconventionalmethods.

40、Suchsitesmakefixtureplacementdifficultorimpossible.Consequently,therecommendationisalways(oremoveanyresidual(pathological)softtissuebythoroughcurettageofthebonywallsandclosetheareaprimarily.Ideally,thisshouldbedonebybringinginfreshperiosteumtopromotehealingbyfirstintention. Littleisknownaboutthelen

41、gthoftimethatshouldpassbetweenthesurgicalremovalofpathologicallyalteredtissuesandtheinstallationoffixturestogivethemoptimalhealingcircumstances.Unloadedfixtureshavebecomesuccessfullyosseointegracedafterinstallationindogsocketsprecededbyimmediateextractionofhealthyteeth.Again,however,humanbonehealsat

42、aslowrate.Waiting9to12monthsgenerallyprovestobethesafestandmostworthwhilealternativeespeciallyif(hepatient'slong-termprognosisofthetreatmentistakenintoaccount. Irradiation InhisdoctoralthesisonCogammairradiationto(herabbittibia,Jacobssonconcludedthatbonehealingwastemporarilydepressedevenafterasing

43、ledoseof5Gy.At15Gy,asignificantdepressionofearlyosteogenesiswasobserved.However,if(hisdosehadbeengivenIyearearlier,theboneformingcapacitywouldhavebeenimprovedbyafactorof2.5relativetoimmediatepreoperativeirradiationtraumaofthesamemagnitude.Consequently,anosseousrecoveryafterirradiationwasobserved.The

44、seresultswere'allrelatedtohealingbone.Maturebonewasrelativelyresistanttoirradiationuptoasingledoseof40Gy,ie,remodelingcontinuedatanormalrateandnovascularchangeswereobservedafter(heirradiation. Clinicaltrialswithfixturesinstalledinpreviouslyirradiatedmaxillary,frontal,andtemporalbonetosupportfacialp

45、rosthesesaftercombinedsurgicalandradiologicaltreatinenthaveyieldedpositiveresults.Jacobssonetalreportedon35fixturesinserted9monthsto37yearsafterirradiation(reatmentwith25to86Gy.Withfbllow-uptimesfromimplantinsertionof15to44months,only5fixtures(14.3%)wereLost. Onthebasisoftheseinvestigations,treatme

46、ntwithfixturesandfacialordentalprosthesesafterirradiationappearsnolongertobeanunattainableobjective,providedtheboneisallowedalongenoughrecoveryperiodaftertheirradiationtrauma.Moreover,irradiatedpatientsfrequentlyare(hemostneedyones. Theeffectsoftreatmentwithcytotoxicdrugshavenotbeenstudied. Presen

47、tattemptstorevitalizeirradiatedbonebytreatmentwithhyperbaricoxygenpriortotheinstallationoffixtureshaveelicitedpositivepreliminaryresults.Furtherdocumentationis,however,needed. Perioperativefactorforfixtureinstallation Implantproperties. Ilisthesurgeon'sresponsibilitytochooseimplants(hatwillmaximi

48、zethepossibilityofosseointegration.Thepropertiesofsuchimplantsandtheirinterfacialreactionswiththehost(bone)tissueshavebeenreviewedindetailelsewhereandareonlysummarizedbelow. Material Commerciallypuretitaniumisclinicallythebestdomment6dmaterialtoachieveosseointegration.Itssurfaceoxidesareverystable

49、in(hebonyenvironmenlandcorrosionisminute.Noallergicreactionstothismaterialarcknown.Consequently,itishighlybiocompatibleand,moreover,easytomachine. Design Ascrew-shapegivessurfaceenlargementforinteractionwiththerecipientbonetissue,enhancesinitialstabilization,providesresistancetoshearforces,anddist

50、ributesloadwellwithinthebone.Incontrasttootherdesigns,screw-shapedtitaniumimplantshavebeenshowntobecometotallyoseointegratedalongtheirentirecircumferenceindogs. Surfaceproperties Theinterfacialreactionsofthebonetissuearegreatlygovernedby(hechemicalandphysicalpropertiesoftheimplantsurface.Thepassiv

51、atingtitaniumoxidesandacertaindegreeofsurfaceroughnesspromoteosseointegration. Surfacepurity Forobviousreasons,thedesiredsurfacepropertiesshouldnotbechangedbymicrobiologicalormetalliccontaminationduringanypartofthemanufacturing,storing,transportation,sterilization,andsurgeryprocesses. Fixturesite

52、positions Themostimportantprincipleistoachievegoodinitialstabilityandfullcoverageofthefixturesinwell-vascularized,highlyosteogenicbone.Bicorticalinitialstabilizationshouldbe(hegoal.Ifthisisnotpossible,onemustresorttoatleastnionocorticalfixation.Possibleareasforbi-andnionocorticalfixationhavebeenrev

53、iewedunder"Localanatomy."Theadditionalstabilitythatcanbeachievedbyengagingthelingualcorticalplateofthemandibleshouldbeusedwheneverpossible. Foradequateloaddistributiontotheboneand(hefixturesthemselves,thelattershouldbespreadwellapartandplacedalongacurveoranyarrangementotherthanastraightline.Thecent

54、erandtheendsofthetentativesuprastructureshouldbewellsupported.However,thefinaldesignandextensionshouldawaittheexperienceofbonequalityfromfixtureandabutmentsurgeries.Nofigureforanyoptimalinterfixturedistancecanbegivenbecausethisdependsonthevitalityandmechanicalcapacityofboththefixturesitesandtheinter

55、fixtureboneandmayvaryfromoneareatoanother.Aclinicalruleofthumbis,however,thattheinterfixturedistanceshouldnotbelessthanonefixturediameter.Thisapproachalsofacilitateslaterhygieneeffortsbetweenabutments. Theanteriorloopofthemandibularcanalandlhenasopalatineductshouldbeavoidedsoasnottointerferewithner

56、vefunctionandosscointcgration. Numberoffixturesites Theavailablebonevolumeindifferentareascanbereasonablywellassessedpreoperativelybypalpationand,especially,bytomographicradiographs.Thesameisnottrueforbonequality,whichcanbeadequatelydeterminedonly'aftersomedrillinghasbeenperformed.Onemayfind,forex

57、ample,thatareasplannedasfixturesitesaretotallyunsuitableduetothepresenceofemptyorfattynarrowcompartments.Consequently,thenumberandpositionoffixturescannotbefinallydecideduponuntiltheperioperativeperiod.Withinthejawsitisgenerallyadvisabletostartdrillingforfixturesitesclosetothemidlineandthenprepareth

58、enextonesasfarposteriorlyaspossible,becausethecentralandposteriorsitesstronglyinfluencetheout-comeoftheentiretreatment.Onlythencandecisionsbemadeonanyintcrpositionalfixturestobeplaced. In(hetotallyedentulousmandible,placementoffixturesfromonemolarareato(heother(ifthepositionofthemandibularcanalallo

59、ws)isnotarecommendedprocedure.Themandibleflexessomewhatduringchewing,andrigidconnectionofsuchfixturestoastiffbridgemaycausemicrofracturesintheperifixturalboneduringmandibularflexing. Fororalpurposes,onefixturecancarryonecrownonly,twofixturesprovideminimalsupportforabridgeinpartialedenlulism,andfour

60、fixturesaretheminimumforafull-archbridge,providedtheyarcspacedwellapartalongacurve.UnpublisheddatafromtheGotcborgteamshowednosignificantdifferencesin5-to12-yearsurvivalratesformaxillaryandmandibularbridgessupportedbyfourorsixfixtures. Inclinationoffixturesites Theinclinationsofthefixturesitesdepen

61、don: 1. Localboneanatomy.Thedominantprincipleisstillthatthefixturesshouldbetotallyembeddedinbone.Thismaycallforlingualorbuccalpositioningoratiltingofafixturesitetoavoidconcavitiesinthebone.Ifnobonegraftsarcplacedintothefloorofthemaxillarysinus,distalliltingofthemarginalpartsoffixturesitesmayalsoben

62、eededinthefirstpremolarregiontoavoidpenetrationintothemaxillarysinus.Moreover,suchaninclinationfrequentlyallowsadvantagelobelakenofthecanineeminence. 2. Jawrelationships.Unlessorthognathicsurgeryisperformedbeforeorpossiblyincombinationwithbonegraftingalfixtureinstallation,pseudoprognathismduetoreso

63、rptiongenerallycallsforbuccalinclinationofmaxillaryandlingualtiltingofmandibularfixturesitesintotaledentulisni. 3. Designoflhesuptastructure.Withproperinclinationoffixturesites,penetrationofbridgescrewcanalsthroughbuccalfacingscanbeavoided.Anoverlypalatalinclinationmay,ontheotherhand,resultinabulky

64、bridgethatinterfereswithphonation. 4. Desireforparallelism.Ifparallelfixturesitesareprepared,theconstructionofthesuprastrucluremaybefacilitated.Thisaspect,howevertakeslastpriority. Lengthsoffixtures Thelengthsofthefixturesshouldbedeterminedonlyafterall"high-speed"drillinghasbeenfinished.Inparticu

65、lar,marginalcountersinkingmayreducethedepthofafixturesite,thenfixturesshorterthanoriginallyanticipatedmustbechosen.Thedepthofafixturesiteshouldbemeasuredwithagraded(ball-point)explorertothelowestmarginalboneedge. Majorcxtrabonyprotrusionsoftheapicalpartsoffixtures(eg,intothemaxillarysinusor(henasal

66、cavities)arenotjustified.Experiencewithsurgicaldisplacementof(heinferioralveolarnervetogainbicorticalfixationinmandibularmolarareasisthusfarlimited. Loadbearingcapacity Theneteffectofalltheconsiderationsdiscussedabovegovernswhatdynamicloadthefixturesareabletobear.Itisthequalityofallperifixturalboneandthetotalinterfacesurfaceofallfixturesthatdetermine(heloadbearingcapacity.Consequently,four15-mm-longfixturesmaybecapableofcarryingthesameloadassix10mmlongones,providedallarestrategicallywellplaced