后退

Group 1 was instrumented with SS-K files by step-back technique, group 2 was instrumented with manual Protaper instruments according to manufacturers' directions.

第一组使用不锈钢K锉采用逐步后退法预备近颊根管，第二组使用手用Protaper采用厂家推荐的方法预备近颊根管，第三组使用机用K3采用逐步深入法预备近颊根管。

Methods: One hundred and twenty teeth with curved root canals were randomly divided into 2 groups: 74 curved root canals in group PT were prepared by ProTaper rotary Nickel-Titanium file with crown-down technique, and 75 curved root canals in group SS were prepared by K-files with step-back technique.

选择2005年6月至12月间本院口腔内科行根管治疗的120例患者（120颗牙），随机分为两组：试验组用ProTaper机用镍钛锉及冠根向预备技术预备弯曲根管74个，对照组用不锈钢K型锉及逐步后退法技术预备弯曲根管75个。

METHODS: 8 curved artificial root canals were prepared with stainless steel K files by the step-back technique, the root canals were digitally photographed, the images were analysed by the software Image-Pro Plus, the shapes and positions of the root canals were measured and analysed. SPSS10.0 software package was used for statistical analysis, paired-samples t test was used to compare the difference of the means among sample groups.

使用手用不锈钢K锉，按逐步后退法预备8个弯曲人工根管，根管预备过程中对根管及根尖孔进行微距摄影，用图像分析软件Image-Pro Plus对根管的形态与位置变化进行测量、分析；实验数据采用SPSS10.0统计软件包进行统计学分析，选用配对t检验比较组间差异。

Methods: Fourty-five mandibular second premolars with single oval-shaped root canal were prepared with step-back technique and filled with warm vertical compaction technique. The teeth were divided into three groups randomly: ProTaper group, Mtwo group and manual stainless group. The operating time was recorded.

45颗具有椭圆形根管的下颌前磨牙经逐步后退法预备、热牙胶垂直加压充填后随机分为3组，分别用ProTaper再治疗器械和ProTaper器械，Mtwo再治疗器械和Mtwo器械，手用H锉和K锉去除牙胶。

Objective To evaluate clinical effect of the handling ProTaper Nickel-titanium rotary instruments in preparation of canals of posterior teeth.Methods 96teeth with pulpitis or periapical periodontitis were instrumented by handling ProTaper rotary instruments using step-down technique,and by K files using step-back technique for control.All teeth were obturated with lateral condensation methods.The efficiency of preparation was analyzed with ra-diographs before and after operation.

目的 评价手用ProTaper预备后牙根管的临床效果方法选取患有牙髓炎和根尖周炎的后牙96例，随机分成试验组和对照组各48例，试验组用手用ProTaper 锥度镍钛旋转器械逐步伸入法预备根管，对照组用K锉，逐步后退法预备根管，两组均用侧向加压充填法充填根管，根据治疗后的X线片，评价后牙根管预备效果。

Methods 96teeth with pulpitis or periapical periodontitis were instrumented by handling ProTaper rotary instruments using step-down technique,and by K files using step-back technique for control.All teeth were obturated with lateral condensation methods.The efficiency of preparation was analyzed with ra-diographs before and after operation.

选取患有牙髓炎和根尖周炎的后牙96例，随机分成试验组和对照组各48例，试验组用手用ProTaper多锥度镍钛旋转器械逐步伸入法预备根管，对照组用K锉，逐步后退法预备根管，两组均用侧向加压充填法充填根管，根据治疗前后的X线片，评价后牙根管预备效果。

objective to evaluate clinical effect of the handling protaper nickel-titanium rotary instruments in preparation of canals of posterior teeth.methods 96teeth with pulpitis or periapical periodontitis were instrumented by handling protaper rotary instruments using step-down technique,and by k files using step-back technique for control.all teeth were obturated with lateral condensation methods.the efficiency of preparation was analyzed with ra-diographs before and after operation.results no transportation,apical blockage and ledge were found in test.the technique could keep canals smooth.there were two ledge,one instrument fracture and nine transportation in control.the operative time was shorter and post treatment pain seldom occurred in handling protaper group.conclusion the handling protaper niti rotary instruments can prepare the canals effectively and safety.after the preparation,the canals could be easily washed,sterilized and filled.it is an efficient instrumentation method for posterior teeth's canals and be used widely.

目的 评价手用protaper预备后牙根管的临床效果。方法选取患有牙髓炎和根尖周炎的后牙96例，随机分成试验组和对照组各48例，试验组用手用protaper多锥度镍钛旋转器械逐步伸入法预备根管，对照组用k锉，逐步后退法预备根管，两组均用侧向加压充填法充填根管，根据治疗前后的x线片，评价后牙根管预备效果。结果试验组无根管偏移、根尖阻塞、台阶，且根管壁平滑流畅，无器械折断等并发症发生。对照组有2例台阶形成，器械折断1例，根管偏移9例。试验组操作时间短且术后疼痛轻微。结论应用手用protaper预备后牙根管快速、安全，成形效果好，易于根管冲洗消毒及填充，可视为临床上预备后牙根管的有效方法。

Then I step back ward and watching it silently, then I see the true feelings.

比如爱一个人，充满变数，我於是后退一步，静静的看著，直到看见真诚的感情。

For example, when you love someone, changes are all around. Then I step back ward and watching it silently, then I see the true feelings.

比如爱一个人，充满变数，我于是后退一步，静静的看着，直到看见真诚的感情。

Forexample, when you love someone, changes are all around. Then I step back ward and watching it silently, then I see the true feelings.

比如爱一个人，充满变数，我于是后退一步，静静的看着，直到看见真诚的感情。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了