Comparative investigation of two rotary nickel-titanium instruments: ProTaper versus RaCe. Part 2. Cleaning effectiveness and shaping ability in severely curved root canals of extracted teeth

AIM: To determine the cleaning effectiveness and shaping ability of ProTaper and RaCe nickel-titanium rotary instruments during the preparation of curved root canals in extracted human teeth. METHODOLOGY: A total of 48 root canals of mandibular and maxillary molars with curvatures ranging between 25 degrees and 35 degrees were divided into two groups of 24 canals each. Based on radiographs taken prior to instrumentation with the initial instrument inserted into the canal, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared using a crown-down preparation technique. After each instrument, the root canals were flushed with a 2.5% NaOCl solution and at the end of instrumentation with NaCl. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. After splitting the roots longitudinally, the amount of debris and smear layer was quantified on the basis of a numerical evaluation scale, using a scanning electron microscope (SEM). The data established for scoring the debris and the smear layer were separately recorded and analysed statistically using the Wilcoxon test. RESULTS: Two ProTaper and three RaCe instruments fractured; there was no significant difference between instrument types (P > 0.05). Completely clean root canals were never observed. For debris removal, RaCe files achieved significantly better results (P < 0.001) than ProTaper instruments. The results for remaining smear layer were similar and not significantly different (P > 0.05). RaCe instruments maintained the original canal curvature significantly better (P < 0.05) than ProTaper instruments. No significant differences were detected between the instruments (P > 0.05) for the time taken to prepare the canals. CONCLUSIONS: Under the conditions of this study, RaCe instruments resulted in relatively good cleaning and maintained the original curvature significantly better than ProTaper did.     

Efficiency of rotary nickel-titanium K3 instruments compared with stainless steel hand K-Flexofile. Part 2. Cleaning effectiveness and shaping ability in severely curved root canals of extracted teeth

AIM: To determine the cleaning effectiveness and the shaping ability of K3 nickel-titanium rotary instruments and stainless steel hand K-Flexofiles during the preparation of curved root canals in extracted human teeth. METHODOLOGY: A total of 60 root canals of mandibular and maxillary molars with curvatures ranging between 25 degrees and 35 degrees were divided into two groups of 30 canals. Based on radiographs taken prior to instrumentation with the initial instrument inserted into the canal, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared by K3 instruments using a crown-down preparation technique or by K-Flexofiles using a reaming motion up to size 35. After each instrument, the root canals were flushed with 5 mL of a 2.5% NaOCl solution and at the end of instrumentation with 5 mL of saline. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. After splitting the roots longitudinally, the amount of debris and smear layer were quantified on the basis of a numerical evaluation scale, using a scanning electron microscope. The data established for scoring the debris and the smear layer were separately recorded and analysed statistically using the Wilcox-on's test. RESULTS: None of the stainless steel K-Flexofiles but 5 K3 nickel-titanium instruments separated. Completely clean root canals were never observed. For debris removal, K-Flexofiles achieved significantly better results (P < 0.001) than K3 instruments. The results for remaining smear layer were similar (P > 0.05). K3 instruments maintained the original canal curvature significantly better (P < 0.0001) than K-Flexofiles. No significant differences were detected between the instruments (P > 0.05) for the time taken to prepare the canals. CONCLUSIONS: Under the conditions of this study, K-Flexofiles allowed significantly better removal of debris than K3 instruments. K3 files maintained the original curvature significantly better. A number of K3 instruments fractured.     

Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile--Part 2. Cleaning effectiveness and instrumentation results in severely curved root canals of extracted teeth

AIM: To determine the cleaning effectiveness and the shaping ability of FlexMaster nickel-titanium rotary instruments and stainless steel hand K-Flexofiles during the preparation of curved root canals in extracted human teeth. METHODOLOGY: A total of 48 root canals with curvatures ranging between 25 degrees and 35 degrees were divided into two groups of 24 canals. Based on radiographs taken prior to the instrumentation with the initial instrument inserted into the canal, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared by FlexMaster instruments using a crown-down preparation technique or by K-Flexofiles using a reaming working motion up to size 35. After each instrument, the root canals were flushed with 5 mL of a 2.5% NaOCl solution and at the end of instrumentation with 5 mL of NaCl. Using the pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. After splitting the roots longitudinally, the amount of debris and smear layer were quantified on the basis of a numerical evaluation scale, using a scanning electron microscope. RESULTS: Completely cleaned root canals were not found with any of the two instruments. In general, K-Flexofiles resulted in significantly less debris(P < 0.001) and less smear layer (P < 0.05) than Flex-Master instruments, but these differences were not significant in the apical third of the canals (P > 0.05). FlexMaster instruments maintained the original canal curvature significantly better (P < 0.0001) than K-Flexofiles. No significant differences were detected between the instruments (P > 0.05) for the time taken to prepare the canals. CONCLUSIONS: Under the conditions of this study, K-Flexofiles allowed significantly better canal cleaning than FlexMaster instruments. FlexMaster instruments maintained the original curvature significantly better.     

Comparative study on the shaping ability and cleaning efficiency of rotary Mtwo instruments. Part 1. Shaping ability in simulated curved canals

AIM: To compare the shaping ability of Mtwo instruments with K3 and RaCe instruments. Part 1 of this two-part report describes the efficacy of these nickel-titanium instruments in simulated curved root canals. METHODOLOGY: Simulated canals with 28 degree and 35 degree curves in resin blocks were prepared with Mtwo instruments using a single length technique and with K3 and RaCe instruments using a crowndown preparation technique (n = 20 canals in each case). Pre- and post-instrumentation images were recorded and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 20 measuring points, beginning 1 mm from the endpoint of preparation. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were also recorded. The data were analysed statistically using ANOVA and Student-Newman-Keuls test. RESULTS: On an average, canals prepared with Mtwo instruments remained better centred compared with those enlarged with K3 or RaCe instruments. Six RaCe instruments, four K3 files and none of the Mtwo instruments fractured during preparation (P > 0.05). In both of the canal types, Mtwo was significantly faster (P < 0.001). It was possible with all types of instruments to control working length as well. CONCLUSIONS: Mtwo instruments prepared curved canals rapidly, respected original canal curvature well and were safe to use.     

2种机用镍钛器械根管成形效果的对比研究

目的:比较2种不同类型机用镍钛根管预备器械Mtwo、K3的根管成形效果.方法:选择36个离体上颌第一磨牙的近中颊侧根管.根据其弯曲度分成A(弯曲度≥20°)、B(弯曲度＜20°)2组,每组再随机分成2个亚组,分别采用镍钛锉Mtwo和K3进行根管预备.预备前后,分别向根管内注入造影剂并拍摄数字X线片,利用合作研制的计算机图像分析软件生成预备前根管几何中心线并投影至预备后根管,测定根管偏移量(几何中心线偏移量)及根管弯曲度的变化.所有数据用SPSS11.0软件包进行统计学分析.结果:各组样本经t检验分析,根管弯曲度≥20°时,根管弯曲起始处的根管偏移量Mtwo组显著小于K3组(P＜0.05);根管弯曲度减小量Mtwo组显著小于K3组(P＜0.05).根管弯曲度＜20°时,Mtwo、K3组间根管偏移量及根管弯曲度减小量均无显著性差异(P＞0.05).结论:Mtwo、K3根管预备时均能良好维持原始根管的中心位置;预备弯曲度大于20°根管时,Mtwo可更好维持原始根管弯曲度及走向.     

机用镍钛器械预备清理根管效果的定量分析

目的:比较机用镍钛根管预备器械ProFile与手动器械对弯曲根管的清理效果.方法:3组弯曲根管分别进行ProFile、手动不锈钢RT锉、NiTiflex锉预备.立体显微镜下观察根管纵截面并采用图象分析软件Scion Image 1.62定量分析根管碎屑分布比例与根尖栓塞的形成.结果:ProFile组碎屑指数小于其他两组;碎屑栓发生率各组无显著性差异,但与根管弯曲部位相关.结论:ProFile器械采用冠根向深入法对弯曲根管碎屑的清理优于手动器械,但仍应注意弯曲位于根尖1/3段者易发生根尖阻塞.     

3种机用镍钛器械在重度弯曲根管预备中根管成形能力的研究

目的：比较机用镍钛Protaper、K3、iRaCe在重度弯曲根管预备中的根管成形能力。方法：收集新鲜拔除的人恒磨牙60颗,要求其中一个根管的弯曲角度为25°～45°,分为Protaper组、K3组和iRaCe组,每组20颗。每颗牙分别在根管预备前后拍摄标准化的平行投照片,通过影像分析来记录根管弯曲度的变化值和根尖偏移量,同时记录折断的器械和根管预备的时间。结果：实验过程中3个组均无器械折断。K3组、iRaCe组在根管预备后根管弯曲角度的变化小于Protaper组,差异有统计学意义（P〈0．05）,K3组和iRaCe组之间差异也具有统计学意义（P〈0．05）。Protaper组、K3组的根尖偏移量大于iRaCe组,差异有统计学意义（P〈0．05）,Protaper组和K3组之间差异无统计学意义（P〉0．05）。三组在操作时间上的差异无统计学意义（P〉0．05）。结论：iRaCe和K3在重度弯曲根管预备中的根管成形能力较Protaper要好,更适合用于重度弯曲根管预备。     

机动ProTaper和Mtwo器械用于弯曲根管预备的临床评价

目的:评价机用ProTaper和Mtwo对弯曲根管的预备效果。方法:将临床需行根管治疗的171颗磨牙随机分为三组,分别采用ProTaper、Mtwo及不锈钢K锉对磨牙弯曲根管进行预备,比较器械折断、根管预备时间、术后反应及根管成型及充填情况。结果:根管预备时间:Mtwo的操作时间5.4 min比ProTaper的6.8 min和不锈钢K锉的13.6min短,ProTaper和Mtwo器械预备的根管锥度和流畅度均好,术后疼痛发生少。结论:ProTaper和Mtwo器械用于预备磨牙弯曲根管,效率高,成形能力佳。Mtwo器械应用常规预备法简单,预备时间短且有效。     

4种镍钛器械预备弯曲根管后成形能力比较

目的:比较4种镍钛器械预备弯曲根管后的成形能力.方法:收集临床上拔除的近颊根牙根弯曲度在20°～40°的上颌第一或第二恒磨牙40颗,随机分为4组,每组10颗,分别采用Protaper Universal、Protaper Next、TF、S3对近颊根进行根管预备.预备前、后采用Micro-CT扫描,使用Mimics17...     

Mtwo镍钛器械在弯曲树脂根管内成形能力的研究

目的 利用弯曲树脂根管研究Mtwo镍钛器械的成形能力。方法 使用机用Mtwo和ProTaper预备两组弯曲树脂根管,记录弯曲树脂根管切割量和弯曲度的变化,并对预备前后弯曲树脂根管形态学改变、根管宽度和弯曲度变化进行分析和比较。结果 两组机用镍钛器械在根管形态学、根管宽度和根管偏移方面无显著性差异。结论 Mtwo镍钛器械能够较好地完成弯曲树脂根管的预备。     

Shaping ability of progressive versus constant taper instruments in curved root canals of extracted teeth

AIM: To compare the shaping ability of progressive versus constant taper shaft instruments in curved root canals of extracted human teeth. METHODOLOGY: A total of 40 root canals of mandibular molars with curvatures ranging between 20 degrees and 40 degrees were divided into two groups of 20 canals each and embedded in a muffle system. The root canals sectioned horizontally at three levels before preparation and then remounted into the mould. All root canals were prepared with ProTaper (progressive taper) or Hero Shaper (constant taper) instruments. Pre- and post-instrumentation radiographs and cross-sectional images were obtained. The parameters evaluated were: working safety (instrument failure, apical blockage and loss of working length) and shaping ability (straightening, cross-sectional area, transportation and centring ability). The data were analysed statistically using Student's t-test. RESULTS: No instrument fractured during preparation. One Hero Shaper instrument permanently deformed. Both instrument systems maintained working length well. The canals prepared with Hero Shaper instruments were straightened to a lesser degree (P < 0.05). ProTaper instruments removed more dentine in the coronal and the middle sections of the canals. Canals prepared with Hero Shaper instruments had less transportation (P < 0.01) and better centring ability (P < 0.05) in the apical section. CONCLUSIONS: Both instrument systems were safe to use and maintained working length well. The canals prepared with Hero Shaper had less transportation and were better centred in the apical region, possibly because their smaller taper reduced instrument stiffness.     

Hyflex CM机用镍钛锉预备磨牙弯曲根管的临床分析

随机选择临床上弯曲度15°~40°(Schneider法)的磨牙根管各30 个分别使用Hyflex CM和ProTaper Universal进行预备,拍摄预备前后定位平行投照数字X线根尖片,比较HyFlex CM和ProTaper预备前后根管弯曲度的改变,评价其对弯曲根管的预备效果.发现Hyflex CM与ProTaper预备后弯曲度分别减少4.54°±3.25°(P<0.001)及5.63°±3.84°(P<0.001);Hyflex CM变直量比ProTaper小1.09 °,但两者间无统计学差异(P>0.05).Hyflex CM可满足临床对弯曲根管的预备要求.