华西口腔课件修复理想桥基牙

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1、IdealabutmentTheidealabutmenttoothcontainsavitalpulp.Ifmostnotbeinferredfromthisthatatreatedtoothwithaproperlyfilledrootcanalisnotsuitableasabridgeabutment;clinicalevidenceindicatesthatinproperlyselectedcasessuchtreatedteethhaverenderedyearsofvaluableservicetothepatient

2、withoutanyharmfuleffects.Nevertheless,thefirstrequisiteinpreparingvitalteethforthereceptionofbridgeretainersispulpconservation.理想的基牙应该是活髓牙。大多数情况下不能这样推断：完善根管治疗后的牙齿不适合作基牙。临床证据表明合理选择的病例中这样的牙齿可以在患者体内服役很多年，没有任何危害。但对作为承担桥固位体的活髓牙来讲，首先要必须考虑的就是保存活髓。Everyeffortshouldbemadeduringt

3、hecuttingoperationstoavoidoverheatingorirritatingthepulpinordertopreventitsfuturedegenerationordeath.Thosepreparationsarecontraindicatedwhichbringtheretainertooclosetothepulp,thusexposingittocontinuousthermalshocks;ifexistingconditionsindicatetheprobabilityofsuchanoccur

4、rence,everypercautionshouldbetakentoreducethedangertoaminimum.在牙体预备时应该尽一切努力来避免过热或激惹牙髓，其目的是预防以后的牙髓变性或坏死。这些牙体预备是不当的，使固位体过于接近牙髓，这样就使牙髓会受连续的热刺激；如果存在的现象表明有可能会出现这样的情况，应该非常的小心来将这种危险减少到最小。Tobesuitableforuseasabridgeabutment,atoothmusthavesufficientbulktowithstandtheforcestoforc

5、eitwillbesubjectedafterthebridgeisattachedtoit.Thisphysicalrequirementisfrequentlycompromisedintheefforttoconservethepulpofatoothwhichisextensivelydecayed.要想成为理想的桥基牙，固定桥戴上之后，在承受力的时候，牙齿必须要有足够的体积来抵抗外力。这种物理方面的要求经常会影响到大面积龋坏的牙齿保存牙髓的活力。Aspreviouslyindicated,abutmentteethsusta

6、inforcesofatypeandmagnitudewhichtheunattachedtoothisnotrequiredtobear;hence,thetypeandamountofperiodontalmembraneattachmentareitemsofimportanceandshouldbedeterminedseparatelyforeachabutmenttooth.正如前面谈到的那样，基牙承受了单个牙齿本身不用承受的特定类型和大小的力；因此，每个基牙附着的牙周膜的种类和牙周膜面积是很重要的，并且都应该分别被评价。

7、Althoughtheidealabutmentisonewhichhasnormalamountofperiodontalattachment,manyteethlackingone-thirdtoone-halfofthenormalamount,whenindiciouslyselected,itisquestionablewhethersuchatoothshouldbeusedasanabutment.Theamountofalveolarboneisdeterminedbytheextentofperiodontalatt

8、achmentandthetypeofbonepresentreflecteditsdegreeoffunction.虽然理想的桥基牙有正常的牙周附着，但很多牙齿的牙周附着是正常量的2/3到1/2，在进行明智的选择的时候