牙體牙髓習(xí)題集與答案

選擇題對(duì)牙髓最具有破壞性的是Nd激光CO2激光紅激光光固化燈牙髓活力電測(cè)定儀感染根管常見的優(yōu)勢(shì)菌不包括普氏菌放線菌G＋細(xì)菌真桿菌梭形桿菌3.備洞時(shí)易損傷牙髓的因素不包括施力大用冷卻劑持續(xù)常時(shí)間鉆磨制備深的窩洞不用冷卻劑4.與頑固性根尖周病變和竇道經(jīng)久不愈可能有關(guān)的細(xì)菌為普氏菌放線菌G＋細(xì)菌真桿菌梭形桿菌5.判斷牙髓活力最可靠的檢查方法是熱診冷診牙髓活力電測(cè)定試驗(yàn)性備洞X線檢查6．診斷殘髓炎最準(zhǔn)確的依據(jù)是叩診牙髓活力測(cè)試病史 癥狀探查治療后根管有痛覺7．急性根尖周膿腫最佳的排膿途徑從牙周間隙排膿從頰、舌側(cè)粘膜或皮膚排出經(jīng)根管從齲洞排膿從上頜竇或鼻腔排膿以上都不對(duì)8．感染侵入牙髓組織的途徑深齲深牙隱裂深牙周袋重度磨耗 以上都有可能9．根尖周炎疼痛最劇烈的階段是粘膜下膿腫期骨膜下膿腫期漿液期根尖膿腫期瘺管形成期10．上頜第一磨牙的根管形態(tài)特點(diǎn)是：c多數(shù)是2根管，即1個(gè)頰根管和1個(gè)腭根管多數(shù)是3根管，即1個(gè)近頰、1個(gè)遠(yuǎn)頰和1個(gè)腭根管多數(shù)是4根管，即2個(gè)近頰、1個(gè)遠(yuǎn)頰和1個(gè)腭根管多數(shù)是4根管，即1個(gè)近頰、2個(gè)遠(yuǎn)頰和1個(gè)腭根管多數(shù)是4根管，即1個(gè)近頰、1個(gè)遠(yuǎn)頰和2個(gè)腭根管11．15號(hào)標(biāo)準(zhǔn)根管銼的銼尖直徑和刃部末端直徑分別是：d0.10mm和0.47mm0.10mm和0.45mm0.15mm和0.45mm0.15mm和0.47mm以上都不對(duì)12．彎曲根管預(yù)備的常見并發(fā)癥是：a根管臺(tái)階藥物性根尖周炎牙周組織壞死皮下氣腫誤戲和誤咽13．根管預(yù)備的工作長(zhǎng)度是指：d牙的實(shí)際長(zhǎng)度從牙冠參照點(diǎn)到牙本質(zhì)牙釉質(zhì)界從牙冠參照點(diǎn)到解剖根尖孔從牙冠參照點(diǎn)到生理根尖孔從牙冠參照點(diǎn)到距生理根尖孔0.5~1mm14．根管成形的標(biāo)準(zhǔn)是：a根管比原來直徑至少擴(kuò)大3個(gè)器械號(hào)根尖預(yù)備到20號(hào)標(biāo)準(zhǔn)器械根管內(nèi)無大量滲出根管沖洗無混濁液體根管內(nèi)無嚴(yán)重氣味15．下列哪一項(xiàng)不是牙髓切斷術(shù)的潛在并發(fā)癥：e根髓感染根管鈣化內(nèi)吸收牙髓壞死髓室穿孔16．下列哪一項(xiàng)描述不是玻璃離子粘固劑修復(fù)術(shù)窩洞預(yù)備的特點(diǎn)（）C玻璃離子粘固劑與牙體組織有化學(xué)粘接，對(duì)固位形的要求可放寬不必作倒凹、鳩尾等固位形去除齲壞牙本質(zhì)，必須作預(yù)防性擴(kuò)展窩洞的點(diǎn)、線角圓鈍洞緣釉質(zhì)不作斜面17．深齲患者激發(fā)痛較重，洞底軟齲能夠徹底去凈，治療方法應(yīng)選擇（）C雙層墊底，一次完成充填治療局麻下開髓失活，行牙髓治療先做安撫治療，待1~2周復(fù)診時(shí)癥狀消除后，再以雙層墊底充填治療實(shí)行活髓切斷術(shù)間接蓋髓、雙層墊底，一次完成充填治療18．臨床上不易查出的繼發(fā)齲可用下列哪些方法幫助診斷（）C探診溫度測(cè)驗(yàn)X線染色法麻醉法19．深齲備洞時(shí)，下列哪項(xiàng)措施是錯(cuò)誤的（）A洞底平、側(cè)壁直，兩相垂直去盡腐質(zhì)保護(hù)牙髓洞緣線圓鈍盡量保留健康牙體組織20．復(fù)合樹脂充填后脫落的原因如下，除了（）A制備了固位形牙齒表面未注意清潔酸蝕后的牙面接觸唾液未制備洞斜面充填體過薄21．下列哪項(xiàng)不是窩洞的基本固位形(B)側(cè)壁固位釘?shù)拦涛坏拱脊涛圾F尾固位梯形固位22．制備倒凹是為了：(B)獲得良好的抗力形獲得良好的固位形便于墊底便于充填便于放置蓋髓劑23．=5\*ROMANV類洞充填備洞時(shí)，要求：(A)適當(dāng)?shù)墓涛恍螄?yán)格的抗力形必須做鳩尾口小底大底平壁直24．右下頜第一恒磨牙頰面齲洞破壞越過邊緣嵴至咬合面窩溝是：(A)=1\*ROMANI類洞=2\*ROMANII類洞=3\*ROMANIII類洞=4\*ROMANIV類洞=5\*ROMANV類洞25．墊底的部位為：(D)僅在髓壁僅在軸壁僅在側(cè)壁僅在髓壁和軸壁任何壁均可墊26．下列說法正確的是B男性患齲率略高于女性齲病流行率主要隨社會(huì)經(jīng)濟(jì)模式而變化齲病流行模式依靠地理環(huán)境而改變遺傳因素對(duì)齲病的發(fā)生和發(fā)展產(chǎn)生重要的影響環(huán)境因素對(duì)齲病的發(fā)生和發(fā)展無影響27．釉質(zhì)齲損害的4個(gè)區(qū)不包括A壞死區(qū)透明帶暗帶損害體部釉質(zhì)表面層28．牙本質(zhì)齲損在光鏡下可看到微生物滲透至牙本質(zhì)小管的區(qū)域是B壞死區(qū)感染層牙本質(zhì)脫礦區(qū)硬化區(qū)修復(fù)性牙本質(zhì)層29．靜止齲屬于B急性齲慢性齲繼發(fā)齲牙釉質(zhì)齲牙骨質(zhì)齲30．病程進(jìn)展快，多數(shù)牙在短期內(nèi)同時(shí)患齲的急性齲稱為E濕性齲慢性齲干性齲繼發(fā)齲猛性齲31WhichisthebestwayofpaincontrolforendodontictreatmentLocalanestheticsDevitalizationAnalgesicsOcclusalreductionIncisinganddrainage32WhichoneisnotthereasonforuseofrubberdamProtectaspirationorswallowingofinstrumentsorirrigantsEliminatethedentalfearofpatientsImprovevisibilityReducedriskofcross-contaminationLegalconsiderations33ThefollowingstatementsarecorrectexceptNearlyallcanalsexhibitacertaindegreeofcurvature.Theremaybemorethanonecanalswithinoneroot.Theapicalforamenusuallyopensattheanatomicalapex.Apicalconstrictionoccursat0.5~1mmfromtheapicalforamen.Lateralandaccessorycanalsmightbethecauseoftreatmentfailure.34WhichoneiswrongregardingtheprincipleofaccesscavityA Straight-lineaccessB ConservationoftoothstructureC UnroofingofthechamberandexposureofpulphornsD FacialsurfaceofanteriorteethE Occlusalsurfaceofposteriorteeth35Theadvantagesofgutta-perchaasafillingmaterialareItiscompactibleandadaptsexcellentlytotheirregularitiesandcontourofthecanalItisradiopaqueItcanbeeasilyremovedfromthecanalwhennecessaryItcanbesoftenedandmadeplasticbyheatorbyorganicsolventsAlloftheabove36Whichoneisincorrectaboutthecriteriaoftherootcanalisreadytobefilledafterthecompletionofrootcanalcleaningandshaping?Thetoothisasymptomatic.Thecanaliswet.Thereisnosinustract.Thereisnofoulodor.Thetemporaryfillingisintact37Whichoneisnotthepathwaysofpulpalandperiapicalinfections?DentinaltubulesPulpexposureGingivalPeriodontalligamentAnachoresis38Tug-backisachievedandthecanalisreadyforfillingWhenthegutta-perchahasextendedbeyondtheapexWhenthegutta-perchaiseasilyremovedfromtherootcanalWhenthegutta-perchaplacedtoapicalconstrictionexhibitsresistanceonremovalAftercementationNoneofabove39Mostrootcanalinfectionsinvolveasingleobligateanaerobicspeciesmultipleanaerobicspeciesonlymixedaerobicandanaerobicmicroorganismsmultipleaerobicspeciesonlynoneofabove40Anabnormallyshapedtooththatmayappearasanextrawidecrown,anormalcrownwithanextraroot,orothercombinationsresultingfromtheunionoftwoadjacenttoothgermsbydentinduringdevelopmentiscalledfusedteethconcresenceofteethgeminatedteethdilacerationsoftoothtaurodontism41Whichisn’tthenon-operativetreatmentofdentalcariesinthefollowing?applicationoffluorideapplicationofAPFgelremineralizativetherapyenameloplastypitandfissuresealing42Whichisnottheaimofoperativetherapyonthedentalcariesmanagement?ToremoveinfecteddentineandprohibitcariesToprotectthepulpandavoidpainToenhancethestrengthofthetoothTofacilitateplaquecontrolTorestoretheappearance(ofteeth)anditsfunction43WhichisthebeststatementaboutresistanceformResistanceformisthedesignofacavityinsuchawaythattheremainingtoothsubstanceandtherestorativematerialcanwithstandmasticatorystressThebulkrequiredwilldependontheflexuralstrengthofrestorativematerial.Inthecaseofamalgamitisestimatedthataminimumof1.5-2mmthicknessoftherestorativematerialisrequiredtowithstandmasticatorystressIfamarginalridgeisfoundtobetooweakinthecauseofanocclusalcavitypreparation,aClassIIcavitymayhavetobepreparedinstead,soastoeliminatetheweakmarginalridge.ThisisparticularlyindicatedwheretheridgeisonlyofenamelthicknessandunsupportedbysounddentineThecavityshouldbedesignedthattheocclusalmarginsofthecavityareinareasnotsubjectedtoexcessiveocclusaltrauma,otherwisetheenamelwallofthecavityand/orthemarginsoftherestorativematerialmayfracture.Inpractice,thismaybeachievedbyplacinganocclusalmarginsofacavityaboutone-quarter(1/4)oftheintercuspaldistance.Note,thateffortsshouldalwaysbemadetoconservesoundtoothtissueAlloftheabove44Whichisthemostdangerareaoftoothindentalcariesoccurredafteryouhavelearneddentalcaries?PitsandfissuresonocclusalsurfacesofmolarsandpremolarsApproximalsurfacesofallteeth.Gingivalthirdsofallteeth,bothonfacialandlingualsurfacesPitsandfissuresnearthelingualofmaxillaryincisorsandcanines(lingualpits)Pitsandfissuresonthebuccalofmolars45Whichisnottrueinthefollowingstatementaboutdentalcariesandmicro-organisms?Cariescouldbeinducedbyspecificbacteria,especiallymutansstreptococci-group(eg.StreptococcusmutansandStrep.sobrinus).Therearecariesoccurredwhenonlyfedacariogenic(highsucrose)diet.Inthe’60sKeyesinfectedgerm-freeanimalswithknownstrainsofstreptococciandfoundthattheseorganismsweretransferredtouninfectedlittermateswhothenbecamesusceptibletocaries.Hethusdemonstratedthatdentalcarieswaspotentiallyinfectiousandtransmissible.Whentalkingaboutcariogenicmicroorganisms,weoftenrefertoStreptococcusmutans,LactobacillusandActinomyces.Occlusalcariescouldbepreventedusingpenicillininanimalstudy.46Theadvantagesglass-ionomercementincludehighadhesionpropertieslowabrasionpropertiesuseasapermanentrestorationreductionincariesduetofluoridereleasingpropertiesalloftheabove47Whichoneofthestatementsiserrorinretentivepinplacementbeavoidedbifurcationandtrifurcationareasparalleltotheexternalsurfaceofthetoothmanypinholesbebetterplacedindifferentplanesthelengthofpinindentineshouldbelongerthanthatofinrestorationbeinthehardestdentine48Thereasonsofspontaneouspainaftertoothfillingincludemistakenlyjudgetheconditionofpulpneglectsmallpulpexposureirritationofmaterialstopulpresidualcariousdentinealloftheabove49Whichofthefollowingisacontra-indicationtoendodontictreatmentDiabetesPregnancyHIV-infectedpatientsPatientsufferingfromheartattackwithinpast6monthsCancer50Centralcuspismostcommoninmaxillarythesecondpremolarsmaxillarythefirstpremolarsmandibularthefirstpremolarsmandibularthesecondpremolarsmaxillarythesecondmolars51Submergeddeciduousteethoccursmostcommoninprimarymaxillarythesecondmolarsprimarymaxillarythefirstmolarsprimarycentralincisorsprimarymandibularthesecondmolarsprimarymandibularthefirstmolars52Inclinicalassessment,whichisnotcorrect?SpontaneousdiscomfortatnightprovideaclueasthetoothisinflamedVitalometertestsareveryunreliableIfthetoothisexcessivelymobile,itmayhaveabnormalrootresorptionSwellingorwithafistuloustractisindicativeofanecroticpulpNopainhistoryaffirmednoinflammation53Ifyoumechanicallyexposethemesiobuccalpulphornontheprimarymaxillaryfirstmolar.Thecariouslesiononthemesialanddistalsurfacesismoderate,thetreatmentnowshouldbePulpcappingwithCa(OH)2;restorwithsilveramalgamPulpotomy;restoredwithastainlesssteelcrownPulpectomy;restoredwithastainlesssteelcrownPulpcappingwithCa(OH)2;restoredwithastainlesssteelcrownExtractionandaspacemaintainer54Thetoothofrootfractureshouldbetreatedwithsplintfor2-3weeks1-2weeks3-8weeks2-3months1-2months55Inwhichsituationbelowthepulpwouldbeexposed?EnamelinfractionEnamelfraciureEnamel-dentinfractureComplicatedcrownfractureUncomplicatedcrown-rootfracture56WeshouldadvocatearoutinedentalappointmentonorbeforetheZERObirthdaythefirstbirthdaythesecondbirthdaythethirdbirthdaythesixbirthday57TheorderofsusceptibilityoftheprimaryteethtocariousattackisasfollowsMandibularprimarymolar>Maxillaryprimaryincisor>Maxillaryprimarymolar>mandibularprimaryanteriorteethMaxillaryprimaryincisor>Maxillaryprimarymolar>mandibularprimarymolar>mandibularprimaryanteriorteethMaxillaryprimaryincisor>mandibularprimarymolar>mandibularprimaryanteriorteeth>MaxillaryprimarymolarMaxillaryprimaryincisor>mandibularprimarymolar>Maxillaryprimarymolar>mandibularprimaryanteriorteethMaxillaryprimaryincisor>mandibularprimaryanteriorteeth>mandibularprimarymolar>Maxillaryprimarymolar58A7year’soldboywithbilaterallossofthemandibularprimaryfirstandsecondmolars,whichofthefollowingmaybebestBandandlooprespectivelyLingualarchRemovableappliancesDistalshoeNoneofthem59ClinicalfeaturesofdentalfluorosisdonotincludeThelesionsymmetricallydistributedinthemouth,butnotallteethareequallyaffectedTheleastaffectedteetharetheincisorsandfirstpermanentmolarsChangesfromfinewhiteopaquelinesrunningacrossthetoothonallpartsoftheenameltofeatureswherepartsofthechalkywhiteandporousouterenamelbecomedetachedanddiscoloredThelossofsurfaceenamelintheseverestcasesresultsinalossofanatomicalformoftheteethWell-demarcatedborderslesionalongincrementalline60Forintrusiveluxationofteeth,themostcommoncomplicationisPulpnecrosisOsteitisRootresorptionAlveolarprocessresorptionAllofabove名詞解釋acquiredpellicleresistanceformindirectpulpcappingretrogradepilpitis自發(fā)痛和激發(fā)痛DentinehypersensitivitySmearlayerPulpotomyInitialapicalfileDentalplaque簡(jiǎn)答題簡(jiǎn)述影響根管沖洗效果的因素簡(jiǎn)述深齲的治療特點(diǎn)簡(jiǎn)述深齲的治療特點(diǎn)簡(jiǎn)述窩洞的基本固位形簡(jiǎn)述牙隱裂的病因Whatisthesequelaeofrootfractures?Pleasebrieflydescribethebenefitsofrootcanalirrigation.Whatisthegoalsofpulptherapyinchildren?WhatarethepropertiesoftheCariogenicBacteria?問答題詳述窩洞的結(jié)構(gòu)及窩洞預(yù)備的基本原則結(jié)構(gòu)引起牙髓活力測(cè)定誤診的原因是什么？根尖周膿腫與急性牙周膿腫的鑒別要點(diǎn)PleasediscussthepurposeofrootcanalpreparationandtheproceduresofStep-downtechnique.Explaintheindicationsandtypesofpulptreatmentforprimaryandyoungpermanentteeth.StateThePrinciplesOfCavityPreparationonAmalgamRestoration.答案一、選擇題

1CCBBD6ECEBC11DADAE16CCCAA21BBAAD26BABBE31BCDEB36CCCAD41DCEAB46EDEDA51DEBDD56BDCEA二、名詞解釋acquiredpellicle唾液蛋白或糖蛋白吸附至牙面所形成的生物膜稱獲得性膜。resistanceform修復(fù)體和余留牙結(jié)構(gòu)獲得足夠抗力，在承受合力時(shí)不折裂的形狀稱抗力形。indirectpulpcapping(P91)用具有消炎和促進(jìn)牙髓－牙本質(zhì)修復(fù)反應(yīng)的制劑覆蓋于洞底，促進(jìn)軟化牙本質(zhì)再礦化和修復(fù)性牙本質(zhì)形成，從而全部生活牙髓的方法叫間接蓋髓術(shù)。retrogradepulpitis逆行性牙髓炎：感染來源于深牙周袋，通過根尖孔或測(cè)副根管逆行入牙髓，引起跟部牙髓的慢性炎癥。自發(fā)痛和激發(fā)痛自發(fā)痛是指患牙在未受到外界刺激而發(fā)生的疼痛。激發(fā)痛是指患牙受到外界刺激而發(fā)生的疼痛。6.DentineHypersensitivityDentinehypersensitivityisaformofhypersensitivitycausedbytheeffectofthermal,tactile,osmoticorchemicalstimulionexposeddentine.7.smearlayerCuttingorabradingthehardtissueswithrotaryandhandinstrumentsproducesalittlechipsorparticleswhichattachedtothetoothsurfaceproducethesmearlayer8.PulpotomyItisindicatedforcariousormechanicalexposuresinprimaryteethandtoinducerootclosuresintheyoungpermanentdentition9.initialapicalfileThefirstfilethatbindsinthecanalatWL.10.dentalplaqueAnadherentdepositsofbacteriaandtheirproducts,whichisnotmineralizedandformsonalltooth,denturerestorationssurfaces.Itisnotanaccidentaccumulationofbacteriabutdevelopsinasequenceofsteps.三、簡(jiǎn)答題簡(jiǎn)述影響根管沖洗效果的因素藥物種類根管的直徑?jīng)_洗的液體量病變情況根管內(nèi)玷污層簡(jiǎn)述深齲的治療特點(diǎn)停止齲病發(fā)展，促進(jìn)牙髓的防御性反應(yīng)保護(hù)牙髓正確判斷牙髓狀況治療方法：墊底充填，安撫治療，間接蓋髓術(shù)簡(jiǎn)述窩洞的基本固位形側(cè)壁固位到凹固位鳩尾固位梯形固位舉例4．簡(jiǎn)述牙隱裂的病因1）牙結(jié)構(gòu)的薄弱環(huán)節(jié)是隱裂牙發(fā)生的易感因素2）牙尖斜度愈大，所產(chǎn)生的水平分力愈大3）創(chuàng)傷性合力5.Whatisthesequelaeofrootfractures?HealingwithcalcifiedtissueHealingwithinterproximalconnectivetissueHealingwithinterproximalboneandconnectivetissueInterproximalinflammatorytissuewithouthealing6.Pleasebrieflydescribethebenefitsofrootcanalirrigation.GrossdebridementFrequencyandvolumeofirrigantIntracanalplacementofdeliveryneedleEliminationofmicrobesDissolutionofpulpremnantsRemovalofthesmearlayerLubricatinginstrument7.Whatisthegoalsofpulptherapyinchildren??Allowingthetoothtoremaininthemouthinanonpathologicstate?Maintenanceofarchlengthandtoothspace?Restorationofcomfortwiththeabilitytochew?Preventionofspeechabnormalitiesandabnormalhabits8.WhatarethepropertiesoftheCariogenicBacteria??Acidogenic:theyareabletoproduceacidrapidlyfromfermentablecarbohydrates.?Aciduric:Theythriveunderacidconditions.?Adherent:Abletoadheretothetoothsurfacebecauseoftheirabilitytosynthesizestickyextracelluarpolysaccharidesfromdietarysugars.四、問答題詳述窩洞的結(jié)構(gòu)及窩洞預(yù)備的基本原則結(jié)構(gòu)洞壁：測(cè)壁，髓壁（軸壁）洞角：線角，點(diǎn)角，軸髓線角洞緣：洞緣角抗力形：洞深，盒狀洞形，階梯結(jié)構(gòu)，窩洞的外形，去除無基釉和避免形成無基釉，薄壁弱尖的處理固位形：側(cè)壁固位，倒凹固位，鳩尾固位，梯形固位原則去凈齲壞組織保護(hù)牙髓組織盡量保留健康牙體組織引起牙髓活力測(cè)定誤診的原因是什么？=1\*GB2⑴引起假陽性反應(yīng)的原因=1\*GB3①探頭或電極接觸了大面積的金屬修復(fù)體或牙齦，使電流流向了牙周組織；=2\*GB3②未充分隔濕或干燥受試牙，以至電流泄漏至牙周；=3\*GB3③液化性壞死的牙髓有可能傳導(dǎo)電流至根尖周，當(dāng)電流調(diào)節(jié)到最大刻度時(shí)，患者可能會(huì)緩慢抬手示意；=4\*GB3④患者過度緊張和焦慮，以致在探頭剛接觸牙面或被問知感受時(shí)即抬手。=2\*GB2⑵引起假陰性反應(yīng)的原因=1\*GB3①患者事先用過鎮(zhèn)痛劑、麻醉劑或酒精飲料等，使之不能正常地感知電刺激；=2\*GB3②探頭或電極未能有效地接觸釉質(zhì)，以致妨礙了電流到達(dá)牙髓；=3\*GB3③根尖尚未發(fā)育完全的新萌出牙，其牙髓通常對(duì)電刺激無反應(yīng)；=4\*GB3④根管內(nèi)過度鈣化的牙，其牙髓對(duì)電刺激通常無反應(yīng)，常見于一些老年患牙；=5\*GB3⑤剛受到外傷的患牙可能對(duì)電刺激無反應(yīng)。3．根尖周膿腫與急性牙周膿腫的鑒別要點(diǎn)急性根尖周膿腫急性牙周膿腫感染來源感染根管牙周袋病史較長(zhǎng)期牙體缺損史牙痛史牙髓治療史長(zhǎng)期牙周炎史牙體情況深齲洞近髓的非齲疾病修復(fù)體一般無牙體疾病牙髓活力多無多有牙周袋無深，迂回曲折膿腫部位靠近根尖部中心位于齦頰溝附近較近牙齦炎膿腫范圍較彌漫局限于牙周袋壁疼痛程度重相對(duì)較輕牙松動(dòng)度相對(duì)輕，病愈后牙恢復(fù)穩(wěn)固明顯，消腫后仍很松動(dòng)叩痛很重相對(duì)較輕X片無明顯異常表現(xiàn)，若患牙為慢性根尖周炎急性發(fā)作者，根尖周牙槽骨顯現(xiàn)透射影像牙槽骨脊破壞，可有骨下袋病程相對(duì)較長(zhǎng)，膿液自根尖周向外排除的時(shí)間約需5－6天相對(duì)較短，一般3－4天可自潰4.StateThePrinciplesOfCavityPreparation.RemovalOfDentalCariesHardstandardStainedstandardProtectpulpUsesharpinstrumentColdtheoperatingtoothbywaterDiscontinuitycuttingorshapingNeverpresstothepulpAnatomyacknowledgesCavitypreparationisasconservativeaspossibleCavitypreparationisasconservativeaspossibleCavitysizeandshapearedictatedmainlybytheextentofthecariouslesion.Thecavosurfaceonlyextendtothesounddentaltissues,notforpreventionEstablishingresistanceandretentionformResistanceformisthedesignofacavityinsuchawaythattheremainingtoothsubstanceandtherestorativematerialcanwithstandmasticatorystress.Toachievethis,thepreparedcavityshouldpossessthefollowingattributes:FlatfloorAdequatebulkoftherestorativematerial,inthecaseofamalgamitisestimatedthataminimumof1.5-2mmAbsenceofweakcuspsormarginalridgesOcclusalcavitymarginsinareasnotsubjectedtoexcessiveocclusaltrauma.Inpracticeone-quarter(1/4)oftheintercuspalwidthFlatflooratrightanglestothelineofstress.Thefloorofpreparedcavityshouldbeflatandrightanglestothelineofocclusalstress,whichisusuallyinthedirectionoflongaxisofthetooth.Soundtoothtissueshould,however,notberemovedsimplytoobtainaflatpulpalfloorofpreparedcavityWallsofthecavityparalleltothedirectionofthestress.Toachievethis,thewallsofthecavityarepreparedparalleltothecorrespondingtoothsurfacesObtainretentionformRetentionform:Retentionformreferstothoseaspectsofcavitypreparationwhichensurethattherestorationisnotdislodgedfromthepreparedcavity.WallsshouldbeparallelorslightlyocclusallyconvergentFlatwallsparallelwithorperpendiculartothetoothsurfacecomposetheformofthesebox-likepreparationsUseofdovetaillockincompoundcavitiesUseofundercuts,pinsandgroovesFlatfloorandroundedbutdefiniteinternallineanglesRetentionforms:UndercutsDovetaillockGroovesandbox