三种器械预备磨牙弯曲根管成形能力的比较

目的　研究手用ProTaper与不锈钢K锉、镍钛合金K锉预备磨牙弯曲根管对根管弯曲度和根尖偏移的影 响。方法　45个弯曲度为20°~40°的磨牙根管,按弯曲度大小排序后分成15个区组,每区组3个根管,再随机分配 至3个不同处理组,每组15个根管。A组采用手用ProTaper系统行冠根向深入法根管预备;B、C组分别采用不锈钢 K锉和镍钛合金K锉行改良逐步后退法预备根管。记录3组根管预备前后根管影像及器械尖端所在位置,测量并 比较3组间根管弯曲度的变化、根尖偏移指数(ATI)和操作时间。结果　A组的根管弯曲度在根管预备前后仅改变 0·28°,明显低于B、C组,ATI亦小于B、C组(P<0·05);B组根管弯曲度的变化和ATI均大于A、C组(P<0·05);A组 的操作时间最短。结论　与不锈钢K锉、镍钛合金K锉比较,采用手用ProTaper预备磨牙弯曲根管成形效果较好, 效率较高。     

超声在下颌磨牙C形根管预备中的应用

目的:比较超声法与手动K锉预备下颌第二磨牙C形根管的临床效果.方法:选取临床上需行牙髓治疗的下颌第一二磨牙C形根管50例,随机分成两组.实验组25例,用Odontoson-M超声仪预备根管;对照组25例,用于动K型锉预备根管.记录并比较根管预备时间.侧压法根管充填后拍摄X线片,分析根管预备和根管允填的效果.比较两组间根管治疗期间急症的发生率.结果:超声法C形根管预备的平均时间为340 s,手动K型锉为620 s,两组问筹异非常显著;X线片示根管内台阶形成超声组2例,K锉组3例;手动K型锉组出现3例根尖阻塞,3例根火偏移.与对照组相比,实验组根管预备效果显著提高,同时治疗期间急症发生率(EIE)有所改善,但未见显著性差异.结论:超声法预备下颌第二磨牙C形根管操作简便、高效实用、安全,是临床上对下颌第二磨牙C形根管进行预备的有效工具.     

冠部预处理对磨牙重度弯曲根管工作长度影响的研究

目的：观察根管冠部预处理对磨牙重度弯曲根管工作长度的影响。方法：选择磨牙根管弯曲度在25°～45°的牙髓炎、根尖炎的460颗患牙588个重度弯曲根管,随机分为A、B、C组,A组153颗磨牙192个根管不预处理冠部,手用不锈钢K锉逐步后退法预备根管,分别测量预备前、后根管长度;B、C组分别用GG钻、机用ProTaper成形锉进行冠部预处理后测量根管工作长度,之后B组151颗磨牙196个根管手用不锈钢K锉逐步后退法预备根管;C组156颗磨牙200个根管机用ProTaper器械完成锉预备根管,两组预备完成后测量根管长度,并对数据进行统计学分析。结果：A组磨牙重度弯曲根管预备前后长度有明显改变（P＜0．01）,B、C组经根管冠部预处理后长度改变差异无统计学意义（P＞0．05）。结论：磨牙重度弯曲根管冠部预处理后测量根管工作长度可以提高根管工作长度测量的准确性。     

镍钛器械Waveone治疗磨牙根管的临床效果

目的 评价使用机用镍钛器械Waveone预备磨牙根管的临床效果。方法 使用新型单根根管预备锉Waveone采用冠向下法预备67颗磨牙,不锈钢K锉采用逐步后退技术预备54颗磨牙。均使用侧方加压技术进行根管充填。比较两组根管预备所需时间、器械分离情况和根管充填效果。结果 使用Waveone进行根管预备根管充填恰充率为91.1%,高于不锈钢器械组的66.7%（P＜0.01）,预备时间为(17.76±1.96)min少于不锈钢器械组的(33.82±2.37)min（P＜0.01）。结论 使用Waveone进行根管预备时间短,预备锥度好根管充填密合度强。     

WaveOne器械预备C形根管成形效果的CBCT研究

目的:应用锥形束CT(Cone-beam CT,CBCT)探讨WaveOne单根锉器械预备C形根管的成形效果。方法:成对收集具有C形根管的离体牙30颗,每对中2颗样本再随机自由分到两组:WaveOne Primary单根锉器械组(WP组)和ProTaper Universal组(PU组),每组15颗。两组分别用相对应器械进行根管预备,叠加预备前后C形根管根冠、根中、根尖部位横截面CBCT扫描图像,对牙本质切削量、遗漏面积百分比、根管预备时间、根管预备意外发生情况进行统计分析,对WaveOne单根锉器械预备C形根管的成形效果进行评价。结果:WP组与PU组牙本质切削量、遗漏面积百分比在根冠部无显著性差异。在根中部和根尖部,WP组较PU组切削量大(P<0.01),而PU组遗漏面积明显较WP组多(P<0.01)。根管预备时间WP组显著少于PU组(P<0.01),差异有统计学意义。根管预备意外发生情况两组间无显著差异。结论:WaveOne单根锉器械在C形根管的预备成形中相对操作简便、成形好、效率高,是较理想的C形根管预备器械。     

ProTaper联合Pathfile镍钛锉预备狭窄弯曲根管的临床评价

目的 比较联合使用ProTaper和Pathfile镍钛锉、单独使用ProTaper镍钛锉、单独使用不锈钢K锉预备狭窄弯曲根管的临床效果.方法 因牙髓炎或根尖周炎需根管治疗的93颗患牙,336个根管,平均分为A组、B组和C组,A组联合使用Pathfile和ProTaper镍钛锉,冠向下法进行根管预备;B组单用ProTaper镍钛锉,冠向下法进行根管预备;C组单用预弯的弹性K锉,逐步后退法进行根管预备.比较3组在根管预备时间、器械折断率、恰填率及根尖偏移率方面的差异.结果 A、B、C组的根管预备时间分别为(8.51±2.32) min、(7.08±1.56) min、( 13.76±3.28) min,差异有统计学意义(F=223.796,P＜0.01).A组器械折断率(0.00％)、台阶形成率(0.89％)、根尖偏移率(7.14％)最低,恰填率(92.86％)最高.3组之间器械折断率、恰填率、台阶形成率和根尖偏移率差异均有统计学意义(P＜0.05).结论 Pathfile和ProTaper镍钛锉联合使用可减少狭窄弯曲根管的预备时间,且安全可靠,根管充填效果好.     

弯曲根管用镍钛器械预备后根管偏移的研究

目的:研究3种镍钛根管预备器械预备后牙弯曲根管产生根管偏移的情况。方法:选择48个弯曲度>25°的下颌第一、二磨牙近中根包埋于Branmante模型中,分别用机动Hero642、Profile和手用ProTaper、不锈钢K锉进行根管预备。拍摄根管预备前后根尖、根中段横截面的影像,测定根管偏移的量、方向和轴中心率。结果:Hero642和Profile在根尖段和根中段根管的偏移显著小于不锈钢K锉,手用ProTaper仅在根尖段小于不锈钢K锉; 3种镍钛器械的轴中心率均低于不锈钢K锉,而镍钛器械组间无显著性差异;镍钛器械和不锈钢器械在根尖段根管中心偏向近中侧,而在根中段不锈钢K锉和手用ProTaper根管中心多数偏向远中侧,与Hero642和Profile有显著性差异。结论:Hero642、Profile和ProTaper在预备弯曲根管时有较小的偏移及良好的中心定位作用,尤其是Hero642和Profile对根尖和根中段成形能力较佳。     

两种根管器械预备后牙根管的体会

目的：比较不锈钢K锉（SS）,ProTaper手用镍钛锉（PT）,预备后牙根管的临床效果。方法：选取需做根管治疗的前磨牙、磨牙110颗,随机分为两组,每组55颗牙。PT组用ProTaper手用镍钛锉冠向下预备技术预备根管。SS组用不锈钢K型锉逐步后退技术预备根管。两组均采用标准牙胶尖侧向加压技术进行根管充填。记录两组根管预备所需时间和根管充填后的效果,进行统计学分析。结果：PT组单根管预备所需时间（6.17±1.31）min,明显低于SS组（13.22±2.32）min,（P〈0.05）,PT组根管适充率（90.91%）,明显高于SS组（70.91%）,（P〈0.05）。两组比较差异有统计学意义。结论：ProTaper手用镍钛锉在后牙根管预备中有明显的优越性,省时省力,具有良好的成形能力和根管清理效果,适充率高。     

手用ProTaper对弯曲根管成形能力评价的研究

目的评价手用ProTaper对弯曲根管的成形能力。方法将16个弯曲人工根管随机分为2组,实验组(PT组)使用手用ProTaper按冠根向深入法预备根管,对照组(SS组)用不锈钢K锉按逐步后退法预备根管;根管预备过程中对人工根管进行数码照相,图像分析软件Image-ProPlus对根管的形态与位置变化进行测量、分析。结果PT组预备完毕时根管弯曲角度均值从预备前的36°减小到26°,弯曲半径均值未见增大,根管壁光滑、流畅,未见根管不良形态形成;SS组预备完毕根管弯曲角度均值减小到22°,弯曲半径均值从6mm增大至11mm,根管壁切削不均衡,出现了根管偏移、根尖孔拉开、根管台阶等不良形态。结论手用ProTaper对弯曲根管成形能力优于不锈钢K锉。     

Protaper手用镍钛锉预备乳磨牙根管的疗效观察

目的观察Protaper手用镍钛锉预备乳磨牙根管的临床疗效。方法选择4～8岁需做根管治疗的患儿160例,乳磨牙160颗,随机分为Protaper手用镍钛锉冠向下法备根组80颗,手用不锈钢K锉逐步后退法备根组80颗,均用注射型Metapex糊剂根充,术后即刻拍片评价根充成功率,术后3 d回访评价疼痛率。结果 Protaper组疼痛率3.75%,不锈钢K锉组疼痛率15.00%(P<0.05),差异有统计学意义。Protaper组成功率95%,不锈钢K锉组成功率83.75%(P<0.05),差异有统计学意义。结论 Protaper手用镍钛锉预备乳磨牙根管疼痛反应轻,快捷高效,临床疗效优于手用不锈钢K锉,值得临床推广。     

Comparison of procedural errors resulting during root canal preparations completed by senior dental students in patients using an '8-step method' versus 'serial step-back technique'

OBJECTIVE: To compare procedural errors that occur in patients during root canal preparation by senior dental students using a new '8-step method' versus the traditional 'serial step-back technique.' STUDY DESIGN: Senior dental students treated 221 root canals of maxillary and mandibular teeth. Instrumentation included coronal flaring with Gates-Glidden reamers and standardized stainless steel K-files in all teeth. A new 8-step method was used to prepare 67 canals using standardized stainless steel hand instruments (8-step SS) and 69 canals using the rotary Nickel Titanium instruments (8-step NiTi). The traditional serial step-back technique (step-back) was used for 85 root canals. In the apical third, reaming or filing motions were used up to sizes 25 and only reaming motion in sizes larger than 25 with the new 8-step method. A filing motion was used in the step-back for all sizes. Root canals of all groups were obturated with gutta-percha points and AH26 using a lateral condensation technique. Pre- and postoperative radiographs were taken of each tooth. Procedural errors were recorded and statistically analyzed using a binomic test for comparison of proportion. RESULTS: Procedural errors detected consisted of 2 canals with transportation (3%) with the 8-step SS, and 3 canals (4%) with transportation with 8-step NiTi. There were no canal obstructions or instrument separations. With the step-back, 20 canals were transported (24%), 7 canals had obstructions (8%), and in 1 canal instrument was separated (1%). CONCLUSIONS: The new 8-step method resulted in fewer procedural errors than the traditional serial step-back technique when senior students prepared root canals in patients either by hand with standardized K-files or by rotary NiTi instrumentation.     

Curved molar root canal preparations using Hero 642 rotary nickel–titanium instruments

AIM: The Bramante method was used to study how the natural curvature of root canals was modified when using the Hero 642 nickel-titanium rotary system. METHODOLOGY: Twenty-four canals were selected in freshly extracted human mandibular molars. Every root canal had an angle of curvature greater than 20 degrees. Roots were embedded in clear casting resin using a plaster mould. Cross-sectional cuts were made in the apical, middle and coronal thirds of each root. A first group (control) of 12 curved root canals was prepared using stainless steel hand instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the Hero sequence according to the manufacturer's instructions. For each sectioning level, the amount of dentine removed, the change of shape factor and the canal centre displacement were calculated with the aid of a digital image analysis system. The results were subjected to the Mann-Whitney U-test. RESULTS: No significant difference occurred in the amount of dentine removed, change of shape factor or canal centre displacement in the coronal and middle thirds of the curved canals. In the apical third, transportation was significantly higher (P=0.0171) with stainless steel hand instruments than with the Hero system. CONCLUSIONS: The original canal shape was maintained better in the apical third of curved canals when using the Hero system in a crown-down technique when compared to a hand preparation technique with stainless steel instruments.     

The quality of apical canal preparation using hand and rotary instruments with specific criteria for enlargement based on initial apical file size

The aim of this study was to compare the quality of apical enlargement of mesiobuccal canals of mandibular molars using conventional stainless steel hand files (K files) and nickel-titanium (Ni-Ti) rotary instruments (LightSpeed). Thirty freshly extracted mandibular molars were randomly assigned to three equal groups (n = 10 each group). The mesiobuccal canals were instrumented with K file using step-back technique without coronal flaring (control; group 1), K file using step-back technique after coronal flaring (group 2), and LightSpeed instrumentation (group 3). Specific criteria for apical enlargement based on initial apical size were used. For step-back techniques, the master apical file sizes were based on the Grossman criterion of three sizes larger than the first file that bound at working length, without coronal flaring (group 1) and with flaring (group 2). For the LightSpeed (LS) group, the master apical rotary sizes were based on the manufacturer's recommendation. Canal cleanliness, canal transportation, and final canal shapes were determined histologically at 1-mm and 3-mm levels short of the working length. Canals were prepared to significantly larger sizes using LS instrumentation than with either hand instrumentation techniques (15-17 ISO units, p < 0.001). LS instrumentation allowed greater apical enlargement with significantly cleaner canals, less apical transportation, and better canal shape than both hand instrumentation groups at both levels (p < 0.05). None of the three techniques was totally effective in cleaning the apical canal space. It was concluded that greater apical enlargement using LS rotary instruments is beneficial as an attempt to further debride the apical third region in mesiobuccal canals of mandibular molars. Instrument designs, alloy properties, and canal curvature are important factors that determine the feasibility of greater apical enlargement in narrow canals.     

Ex vivo study on root canal instrumentation of two rotary nickel–titanium systems in comparison to stainless steel hand instruments

Aim  To investigate instrumentation time, working safety and the shaping ability of two rotary nickel–titanium (NiTi) systems (Alpha System and ProTaper Universal) in comparison to stainless steel hand instruments.
Methodology  A total of 45 mesial root canals of extracted human mandibular molars were selected. On the basis of the degree of curvature the matched teeth were allocated randomly into three groups of 15 teeth each. In group 1 root canals were prepared to size 30 using a standardized manual preparation technique; in group 2 and 3 rotary NiTi instruments were used following the manufacturers' instructions. Instrumentation time and procedural errors were recorded. With the aid of pre- and postoperative radiographs, apical straightening of the canal curvature was determined. Photographs of the coronal, middle and apical cross-sections of the pre- and postoperative canals were taken, and superimposed using a standard software. Based on these composite images the portion of uninstrumented canal walls was evaluated.
Results  Active instrumentation time of the Alpha System was significantly reduced compared with ProTaper Universal and hand instrumentation ( P  <   0.05; anova ). No instrument fractures occurred in any of the groups. The Alpha System revealed significantly less apical straightening compared with the other instruments ( P  <   0.05; Mann–Whitney U test). In the apical cross-sections Alpha System resulted in significantly less uninstrumented canal walls compared with stainless steel files ( P  <   0.05; chi-squared test).
Conclusion  Despite the demonstrated differences between the systems, an apical straightening effect could not be prevented; areas of uninstrumented root canal wall were left in all regions using the various systems.     

三种方法预备后牙细弯根管的比较

目的探讨逐步后退法、逐步深入法、被动逐步后退法（超声波与手用器械联合应用、三种不同方法预备后牙细弯根管对根管壁的清理能力及操作时间的差别。方法应用逐步后退法、逐步深入法、被动逐步后退法（超声波与手用器械联合应用）对45个新鲜拔除的人恒磨牙近中颊侧根管进行预备．并记录操作时间，将牙根纵向劈开，分为根冠1／3、根中1／3及根尖1／3，扫描电镜下评价其根管内壁牙本质碎屑和玷污层的形成情况。结果三种方法对根管清理能力差异无统计学意义（P〉0．05）而无论使用何种预备方法，其对根中1／3及根冠1／3处的清理能力优于根尖1／3部．两者差异有统计学意义（P〈0．05）。3种方法根管预备时间分别为：逐步后退法（12．8±1．26）min．逐步深入法（9．02±0．74）min，被动逐步后退法（超声与手用器械联合应用法）（12．21±1．90）min．三组差异无统计学意义（P〉0．05）。结论三种根管预备方法均不能达到完全的根管清理，尤其是对于根尖1／3部，清洁效果很不理想：总体上看，根中及根冠1／3清洁度显著优于根尖1／3。被动逐步后退法（超声与手用器械联合应用）及逐步后退法操作均较费时、费力，而逐步后退法根管预备时间略短于另两种方法且较省力。     

Micro-CT评价不同弯曲度根管预备后根尖偏移的实验研究

目的使用Micro—CT评价不同弯曲度根管预备后的根尖偏移。方法选取10颗离体上颌磨牙共30个根管。根据不同的弯曲度分为轻度、中度和重度弯曲共3组根管,每组10个根管。使用不锈钢K型锉采取逐步后退法预备根管,分别于预备前、中和后进行Micro—CT扫描,评价根管的根尖偏移情况。结果根管预备至25号锉时,各弯曲度根管组间的根尖偏移差异有统计学意义;预备至35号锉时,重度弯曲根管组与轻度和中度弯曲根管组间差异均有统计学意义,而轻度和中度弯曲根管组间差异无统计学意义。各组预备至35号和25号时的根尖偏移差异均有统计学意义。结论根管弯曲度越大,根尖偏移度越大;根管预备锉的号码越大,根尖偏移越明显。     

Preparation of the apical part of the root canal by the Lightspeed and step-back techniques

This study measured in vitro the displacement of natural canal centres in 18 human teeth before and after shaping by the step-back or Lightspeed techniques. Experimental roots ( n = 9 per group), embedded in clear plastic, were cross-sectioned using a 0.1-mm-thick band saw at distances 1.25 mm, 3.25 mm and 5.25 mm from the apices. A stereo microscope was used to take 35 mm slides of the cut surfaces of the sectioned roots and canals. The slides of the uninstrumented canals were scanned into a computer and saved. Each sectioned root was then reassembled and the canals shaped by the step-back or Lightspeed technique. File size 40 and instrument size 50 were selected as the master apical file and master apical rotary for the step-back and Lightspeed groups, respectively. The 18 prepared canals were photographed, and the 35 mm slides scanned and computer stored as previously. This allowed the positions of the pre- and postinstrumented roots to be electronically superimposed for subsequent analyses. Displacements of the root canal centres before and after preparation were assessed in relation to the cross-sectional diameter of the files or instruments used. In addition, increases in cross-sectional area of the root canals after preparation were evaluated in relation to the cross-sectional area of the files or instruments used. Engine-driven nickel-titanium Lightspeed instruments caused significantly less ( P < 0.001) displacement of the canal centres, so roots in the Lightspeed group remained better centred than those in the step-back group. The mean cross-sectional area after preparation in the Lightspeed group was significantly less ( P < 0.001) than that recorded in the step-back group. Clinically, this implies less apical transportation and less dentine destruction with the Lightspeed technique than with the step-back technique.     

Anatomic Endodontic Technology (AET)--a crown-down root canal preparation technique: basic concepts, operative procedure and instruments

AIM: To illustrate the conceptual basis and the operative procedure of the Anatomic Endodontic Technology (AET) technique and to illustrate the specific instruments used in each phase. SUMMARY: The basic characteristics of the AET technique are reported. The instruments and procedure are described in three phases: coronal access, coronal-middle preparation and apical preparation. In the first phase, correct cavity design is described. In the coronal-middle phase, the use of four stainless steel shaping instruments, powered by a reciprocating handpiece is described, incorporating a brushing-milling action against canal walls. During the apical phase, dedicated apical stainless steel and NiTi hand instruments are used to complete the preparation. The stainless steel apical files are used with a 1/4 turn and withdrawal movement whilst the NiTi are used in 360 degrees rotary motion. KEY LEARNING POINTS: Most current canal shaping techniques do not prepare all the canal walls and can result in over-enlargement in some areas. AET defines three regions of the canal: coronal (from the cavo-surface of the access cavity), coronal-middle, and apical. Coronal-middle instrumentation is undertaken with four mechanically driven stainless steel shaping instrument used in brushing-milling action against canal walls. Apical preparation is completed by hand and with the formation of a stop.     

Analysis of the gutta-percha filled area in C-shaped mandibular molars obturated with a modified MicroSeal technique

Aim  To analyse the gutta-percha filled area of C-shaped molar teeth root filled with the modified MicroSeal technique with reference to the radiographic features and the C-shaped canal configuration.
Methodology  Twenty-three mandibular second molar teeth with C-shaped roots were classified according to their radiographic features as: type I – merging, type II – symmetrical and type III – asymmetrical. The canals were root filled using a modified technique of the MicroSeal system. Horizontal sections at intervals of 600 μm were made 1 mm from the apex to the subpulpal floor level. The percentage of gutta-percha area from the apical, middle and coronal levels of the radiographic types was analysed using the Kruskal–Wallis test. Complementary analysis of the C-shaped canal configurations (C1, C2 and C3) determined from cross-sections from the apical third was performed in a similar way.
Results  No significant differences were found between the radiographic types in terms of the percentage of gutta-percha area at any level ( P  > 0.05): apical third, type I: 77.04%, II: 70.48% and III: 77.13%, middle third, type I: 95.72%, II: 93.17%, III: 91.13% and coronal level, type I: 98.30%, II: 98.25%, III: 97.14%. Overall, the percentage of the filling material was lower in the apical third ( P  < 0.05). No significant differences were found between the C-shaped canal configurations apically; C1: 72.64%, C2: 79.62%, C3: 73.51% ( P  > 0.05).
Conclusions  The percentage of area filled with gutta-percha was similar in the three radiographic types and canal configuration categories of C-shaped molars. These results show the difficulty of achieving predictable filling of the root canal system when this anatomical variation exists. In general, the apical third was less completely filled.     

Root canal transportation with a Ni-Ti rotary file system and stainless steel hand files in simulated root canals.

OBJECTIVE: The purpose of this study was to compare the root canal transportation of the crown-down technique performed with the Ni-Ti rotary ProFile system (Dentsply/Maillefer), with the step-back technique using stainless steel K-Flexofiles (Dentsply/Maillefer). METHOD AND MATERIALS: Thirty simulated root canals in resin blocks were equally divided into 2 groups. The first group was instrumented with the ProFile system in a crown-down technique and the second group with hand K-Flexofiles in a step-back technique. After instrumentation, resin blocks of both groups were scanned by a transparency scanner, and the derived images were superimposed with the scanned image of an uninstrumented block. Transportation was digitally calculated by a computer software, and results were statistically evaluated by Student t test. RESULTS: Statistically significant differences (P < .05) were found among the 2 groups at 1, 2, 4, 5, and 6 mm from the apical foramen. No statistically significant difference was detected at 3 mm from the apical foramen. CONCLUSION: ProFile caused less transportation at 1 and 2 mm from the apex, whereas at 3 mm, both instrumentation techniques caused the same transportation. Standard deviation was less in the ProFile group than in the hand file group, indicating a more standardized preparation.