逐步后退法—一种清理和成形具佳的根管扩大法

根管扩大的要求是既能清理又要使根管的成形佳。根管扩大方法颇多，诸如标准的根管扩大法、逐步后退法、逐步深入法、抗弯曲根管预备法以及超声法等。其中逐步后退法（step-backmethod）最具优越性．应用最广，无论直的或是弯曲的根管均可采用，尤其对弯曲细小很管的预备，更有独到之处。有人认为现代的许多根管扩大法，都是在逐步后退法的基础上发展起来的。逐步后退法预备根管，步骤如下：（1）根尖段（根管下1／3）预备（附图a）：选用一根既能伸入根管达到牙本骨质界（距X线片报尖约lmm），又稍有摩擦感的挫，作为最开始选用的控称为为…     

感染根管预备后根管内细菌种类和数量的变化

目的：研究根管预备对单根管牙根管内细菌数量和种类的影响。方法：选择21颗患慢性根尖周炎的单根管牙，用K锉行逐步后退法预备根管后再超声处理1min，分别于预备前，逐步后退法预备后，超声处理后根管内取样接种，然后检测根管内细菌数量和检出率的变化。结果：机械预备和超声处理后细菌数量明显降低，与预备前有显著性差异（P＜0．05），细菌检出率明显减少或清除根管内细菌。     

根管预备后超声冲洗的临床研究

目的 对不同方法根管预备后超声冲洗进行临床评估。方法 将121例患者144颗患牙，随机分成四组：手用不锈钢K锉组；手用不绣钢K锉＋超声冲洗组；机用不锈钢K锉组；机用不绣钢K锉＋超声冲洗组。手用不绣钢K锉采用逐步深入法预备根管，机用不绣钢K锉采用逐步后退法预备根管。比较四组根管预备后疼痛发生情况率、根管充填质量、根尖偏移和倜枝根管充填情况，以及根管充填一年疗效观察。结果各组根管预备后疼痛无显著性差异（P〉0．05）。超声组侧枝根管充填率高于单纯手用和机用组。术后一年复查98颗，相应各组无显著性盖异（P〉0．05）。结论 根管预备后超声冲洗，对降低术后疼痛及提高临床治疗有效率无明显效果；但可以提高侧枝根管充填率。     

后牙弯曲细小根管预备方法之成形作用研究

对常规法、逐步后退法和超声法３种方法预备不同弯曲度后牙细小根管的成形作用进行比较研究。结果：逐步后退法术后弯曲度改变及根尖偏移均较少，成形作用较好；而常规法最差。所以认为：预备轻中度弯曲细小根管，逐步后退法为首选；常规法不适用于后牙弯曲细小根管的预备。     

逐步后退法和逐步深入法根管预备后约诊间痛发生的比较

目的 比较2种根管预备方法约诊间痛的发生情况。方法 对144例患者的23l颗患牙分别采用逐步后退法和逐步深入法进行根管预备，观察各自约诊间疼痛的发生情况。结果活髓牙中，分别有14．7％(逐步后退法组)和13．1％(逐步深入法组)发生约诊间痛，两组间无显著性差异。死髓牙中，分别有28．0％(逐步后退法组)和15．5％(逐步深入法组)发生约诊间痛，逐步后退法组明显高于逐步深入法组。结论 对死髓牙患者，采用逐步深入法进行根管预备可以减少约诊间痛的发生。     

平衡力法预备弯曲根管的临床评价

目的：评价用平衡力法预备弯曲根管的临床疗效。方法：选取有弯曲根管的牙髓炎和根尖周炎患牙48个，试验组用弹性K锉(Flexofile)，使用平衡力法预备根管；对照组用K挫，逐步后退技术预备根管，两组均用侧向加压充填法充填根管，根据治疗前、中、后的x线片评价根管预备和充填的效果。结果：两组在根管预备中无器械折断。试验组无根尖阻塞、台阶形成等并发症发生，发生根管偏移少，能较好地维持根管的弯曲度和走向。对照组1例有台阶形成，发生根管偏移的明显多于试验组(P＜0．05)。结论：平衡力法预备弯曲根管可以节约成本，缩短操作时间，较好地维持根管的定向和弯曲度，减少根管偏移。安全有效，实用性强，可作为临床上预备弯曲根管的有效方法。     

Hero 642根管预备系统在弯曲根管应用中的比较研究

目的:比较研究机用镍钛器械Hero 642根管预备系统对弯曲根管采用不同预备方法的临床效果.方法:选取有弯曲根管的牙髓炎或根尖周炎患牙164个,分为3组,分别应用Hero 642根管预备系统和不锈钢K锉采用逐步深入法或逐步后退法预备根管,均采用侧方加压法充填根管,根据X线片评价根管预备效果和充填效果,术后随访半年评价临床疗效.结果:与传统的不锈钢K锉相比,Hero 642根管预备系统采用两种方法预备根管均能较好地维持根管的走向和弯曲度以及根管的锥度和流畅度,术后并发症少且程度轻,逐步后退法术后疼痛和器械折断的发生率较逐步深入法多.结论:机用镍钛器械Hero 642根管预备系统预备弯曲根管成形效果好;采用逐步深入法术后并发症少.     

三种方式预备磨牙重度弯曲根管的比较研究

目的研究3种方式预备磨牙重度弯曲根管的效果。方法牙髓炎、根尖周炎患者497个重度弯曲根管，根管弯曲度为25°～45°，按就诊顺序分为3组，A组167个根管应用G型钻联合手用不锈钢K锉采用逐步后退法预备根管，B组168个根管采用ProFile镍钛器械逐步深入法预备根管．C组162个根管采用不锈钢K锉逐步后退法预备根管。观察3组根管预备所需时间和形成台阶、器械折断、术后反应情况。结果A、B、C组根管预备平均时间分别为（173．55±32．38）s、（171．39±36．68）s和（230．42±45．76）S，A组与B组所用时间差异无统计学意义（t=1．08，P〉0．05），A组和C组（t=13．01，P〈0．01）、B组和C组（t=12．97，P〈0．01）所用时间经f检验差异有统计学意义，C组所厢时间多于A组、B组；3种方式预备磨牙重度弯曲根管，A组并发症发生率为20．96％，B组为24．40％，C组为41．98％，经卡方检验，差异有统计学意义（χ2=9．07，P〈0．05）。结论G型钻联合手用不锈钢K锉预备根管可节省预备时间，操作简单易行。     

手用Protaper根管预备技术的临床运用

根管治疗是治疗牙髓病及根尖周病的最佳选择，高质量地完成根管预备和根管充填是根管治疗成功的关键。本文采用手用Protaper扩大锉和传统ISO手用不锈钢挫（Kfile）分别采用冠向下法（crown—doun）和逐步后退法（step back）扩大后牙根管的两组病例加以比较，现报告如下。     

两种根管预备方法对根管治疗约诊间痛的临床观察

目的：探讨两种根管预备方法对约诊痛的影响。方法：对246个患牙（其中活髓牙141个,死髓牙105个）,随机分为逐步后退法组126个牙,采用不锈钢K锉逐步后退法进行根管预备;逐步深入法组120个患牙采用Pro—Taper手用锉逐步深入法进行根管预备,比较两种预备方法约诊间疼痛的发生情况。结果：活髓牙中,逐步后退法组有16．9％,逐步深入法组有10％的患牙发生约诊间痛,两组间差异无显著性;死髓牙中,逐步后退法组有32％、逐步深入法组有12％的患牙发生约诊间痛,逐步后退法明显高于逐步深入法。结论：对死髓牙,采用ProTaper手用锉逐步深入法预备根管可以减少根管治疗约诊间痛的发生。     

三种方法预备下颌第二磨牙C形根管成形效果的比较

目的 评价3种常用根管预备方法对C形根管的成形效果,为临床治疗提供参考.方法 对临床拔除的具有C形根管的下颌第二恒磨牙60颗,应用改良Bramante技术,于距根尖2mm、5 mm和8mm处将牙根横断.选择手用不锈钢K锉逐步后退技术(Step-Back组)、逐步深入技术(Step-Down组)和机用旋转镍钛锉ProTaperTM系列冠向下预备技术(Crown-Down组)预备不同类型的C形根管,比较预备前后根管横截面形态的数码图像,对3种不同方法的成形效果进行评价.结果 3种方法预备离体下颌第二磨牙C形根管后均有遗漏.不锈钢K锉逐步后退技术和不锈钢K锉逐步深入技术分别在根冠部[遗漏面积百分比分别为(0.177±0.071)%、(0.068±0.074)%]和根尖部[遗漏面积百分比分别为(0.236±0.167)%、(0.295±0.171)%]遗漏较少(P＜0.05).CⅠ、CⅡ型遗漏出现在近远中多于颊舌侧,将其分为独立的2～3个根管预备可减少遗漏.不同方法预备根尖区的遗漏均显著高于根管中上部(P＜0.05).结论 早期开敞根管上段,将C形根管分为2～3个独立的根管进行预备,可以增进根管预备的成形效果.     

Scanning electron microscope study comparing four root canal preparation techniques in small curved canals

Various instrumentation techniques have been proposed and examined with conflicting results. They include hand and ultrasonic techniques and combinations of the two. In the present study we assesed the effectiveness of four preparation methods for cleaning small, curved root canals, using backscattered-imaging scanning electron microscopy (SEM). The methods were: (i) step-back without initial coronal flaring; (ii) step-back with coronal flaring; (iii) step-back with initial coronal flaring and finished by ultrasonic irrigation; and (iv) ultrasonics only.
Eighty freshly extracted maxillary and mandibular molars were randomly placed into four treatment groups of 20 teeth each. After preparation, roots were sectioned longitudinally and examined wet by SEM. Each canal was qualitatively evaluated and the groups compared for removal of debris and smear layer, both overall and at each level (apical, middle and coronal).
There were no statistically significant differences between the techniques, either overall or within any of the regions. When comparing regions (regardless of technique) the middle level was cleaner than the apical or coronal levels.
In conclusion, efficacy differed little among the techniques; none of them completely removed smear layer and all left debris.     

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目的    比较3种机用镍钛根管预备器械 ProTaper、Mtwo、K3的根管预备效果。方法    选取2009年9月至2010年9月在中国医科大学口腔医学院口腔外科新鲜拔除的54颗上颌第一磨牙的近中颊根,根据其根管弯曲度分成A组（弯曲度≥20°）和B组（弯曲度< 20°）,每组再随机分成3个亚组（P组、M组、K组）,分别采用镍钛锉ProTaper、Mtwo和K3进行根管预备。预备前后,分别拍摄数字X线片,利用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,测定根管偏移量及根管弯曲度的变化并且通过扫描电子显微镜观察其中的21例样本根管预备后碎屑和玷污层的分布及评分。结果    根管弯曲度≥20°时,根管弯曲起始处的根管偏移量及根管弯曲度减小量ProTaper组和Mtwo组均显著小于K3组（P < 0.05）;根管弯曲度<20°时,ProTaper、Mtwo、K3组间根管偏移量及根管弯曲度减小量差异均无统计学意义（P > 0.05）。扫描电镜下,P组、M组、K组3者根管冠1/3处碎屑评分差异无统计学意义（P > 0.05）,而在根中1/3及根尖1/3处评分差异有统计学意义（P < 0.05）,其中K组与P组、M组有显著差别（P < 0.05）,3组各部分玷污层评分差异均无统计学意义（P > 0.05）。结论    ProTaper、Mtwo、K3预备上颌磨牙轻度弯曲根管均具有良好的成形能力,Mtwo预备磨牙中、重度弯曲根管能更好维持原始根管走向;配合NaOCl和EDTA冲洗条件下,ProTaper和Mtwo对根管中下段的清理效果优于K3。     

A scanning electron microscopic study of debris and smear layer remaining following use of GT rotary instruments

AIM: The aim of the present study was to assess debris and smear layer remaining following canal preparation with GT rotary instruments. METHODOLOGY: Sixteen freshly extracted single-rooted premolar teeth were instrumented with GT rotary instruments using a crown-down preparation technique. All specimens were flushed with 2 mL of 5% NaOCl between each rotary instrument. At the end of instrumentation the following final irrigation sequence was repeated two times: 2 mL of EDTA + Cetrimide for 1 min (Largal Ultra, Septodont, France) and 2 mL of 5% NaOCl for 5 min. A final flush with saline solution was made to halt any chemical activity. Two other uninstrumented teeth that were not irrigated served as controls. All teeth were split longitudinally and prepared for SEM evaluation. The presence of debris and smear layer was evaluated from photomicrographs at x200 and x1000 magnification taken in the apical, middle and coronal thirds of the canals. Blind evaluation was performed by two trained observers and scores were compiled separately. A five category scoring system for debris and smear layer was used. Values obtained were tabulated and statistical analysis was carried out using a parametric chi-squared test. RESULTS: Statistical analysis showed that there was no significant difference between the three regions of the root canals (P > 0.05) for debris. Comparison of the removal of the smear layer between the three regions showed that there was a statistically significant difference between all parts, especially between the coronal and apical thirds (P < 0.001). Overall, the coronal sections were cleaner than the middle and apical sections. The uninstrumented canals showed walls completely covered with tissue, confirming that specimen preparation alone did not remove tissue. CONCLUSIONS: Under the conditions of the present study GT rotary instruments removed debris effectively, but left root canal walls covered with smear layer, particularly in the apical third.     

The removal of the smear layer using the Quantec system. A study using the scanning electron microscope

AIM: The aim of this study was to determine the ability of the Quantec Series 2000 rotary nickel-titanium endodontic system to remove dentinal debris and smear layer produced during canal preparation. METHODOLOGY: A first group (control) of 12 curved root canals was prepared using conventional manual instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the complete Quantec sequence according to the manufacturer's instructions. In both groups, irrigation was performed using a 3% NaOCl solution. The canal walls were observed under a scanning electron microscope and the coronal, middle and apical thirds of each canal photographed at a magnification of 500. The views were divided into 10 subareas by overlaying a grid, and the absence or presence of a smear layer was rated and scored on three appearances using the scale described by Ciucchi et al. (1989). RESULTS: The scores were higher (i.e. less debris was present) in the middle third (P < 0.0001) and in the apical third (P < 0.0001) of canals prepared with the Quantec system when compared with those prepared with K-files. Nevertheless, in canals prepared with Quantec instruments, the scores were significantly higher in the coronal third compared with the apical third (P < 0.005). CONCLUSIONS: The Quantec rotary system produced cleaner canal walls than conventional manual instrumentation, particularly in the middle and apical thirds. This finding may imply that stresses applied to the cutting regions of Quantec instruments by accumulation and compression of the smear layer are minimized.     

The effectiveness of manual and rotary techniques in the cleaning of root canals: a scanning electron microscopy study

AIM: The purpose of this scanning electron microscope (SEM) study was to compare the cleanliness of the root canal walls following either a manual or a rotary technique of canal instrumentation. The hypothesis was that a rotary technique would produce a cleaner root canal. METHODOLOGY: Manual filing was performed on 10 extracted teeth using stainless steel S-files (Sjodings, Sendoline, Sweden). Powered instrumentation was carried out on a further 10 extracted teeth, using ProFile rotary nickel-titanium files in a handpiece (250 r.p.m.) according to the manufacturer's instructions. A solution of 0.5% sodium hypochlorite was used for irrigation. The roots were cut longitudinally and the canal walls were examined for debris and smear layer at the apical, middle and coronal level. RESULTS: Significantly less debris was found in the apical region using the manual filing technique (P < 0.05); no significant differences could be found at the other levels. Overall, significantly less debris was found on the root canal walls using the manual technique when the data from the three levels were compared (P = < 0.05). CONCLUSIONS: The manual technique employed in this study produced cleaner root canal walls than the rotary ProFile technique.     

不同质量分数乙二胺四乙酸糊剂对根管壁不同区域玷污层的去除效果评价

目的研究不同质量分数乙二胺四乙酸（EDTA）糊剂去除根管壁玷污层的效果以及对根管壁的腐蚀作用。方法选择60颗离体单根管牙,用逐步后退法预备根管,预备后随机分成6组,采用不同质量分数的EDTA糊剂对根管进行处理,分别为5%、10%、15%、17%和20%EDTA糊剂,另设生理盐水组作为对照。处理时先将EDTA糊剂输送进根管内,作用3 min后以5.25%次氯酸钠溶液冲洗,次氯酸钠溶液用量为5 mL。处理后将牙根沿颊舌向纵向劈开,用扫描电镜观察根管壁不同部位玷污层的去除效果和牙本质的腐蚀状况,分别进行评分。结果随着EDTA糊剂质量分数的增加,对根冠1/3、根中1/3玷污层的去除效果明显增加。15%EDTA糊剂可以有效地去除根冠1/3和根中1/3的玷污层,根尖1/3去除效果稍差;对根管壁无明显的腐蚀破坏现象。17%和20%的EDTA糊剂对玷污层的去除效果明显,但对根管壁的结构造成了一定的腐蚀破坏。结论经不同质量分数的EDTA糊剂处理,根管壁玷污层的去除效果不同;质量分数大于17%的EDTA糊剂会对根管壁造成腐蚀。     

不同方法预备根管对根管治疗后牙齿冠渗漏的影响

目的采用3种不同方法预备根管,评价其对根管治疗后牙齿冠渗漏的影响。方法48颗单根管离体牙随机分为4组,使用不同的根管预备方法去除根管壁的玷污层。A组为对照组,采用生理盐水和过氧化氢溶液冲洗根管;B组采用乙二胺四乙酸（EDTA）凝胶和5.25%次氯酸钠溶液冲洗;C组采用Odontoson-M型超声波治疗仪荡洗;D组采用脉冲Nd: YAG激光照射。每组取2颗牙,于扫描电子显微镜（SEM）下观察冠部玷污层的去除情况;其余10颗牙采用Obtura Ⅱ高温注射式热牙胶垂直加压法充填根管,氧化锌丁香油黏固剂封闭根管口,浸于质量浓度20 g·L-1亚甲基蓝溶液中染色7 d,脱水脱钙制作透明牙标本,体视显微镜下测量染料渗入的深度。结果SEM观察：A组
整个根管内壁被覆玷污层及大量碎屑,牙本质小管被堵塞;B组与C组根管内壁清洁,玷污层消失,牙本质小管开放;D组根管内壁牙本质小管封闭或半封闭,玷污层熔融消失。A、B、C、D组染料渗入深度分别为（2.15±0.38）、（1.75±0.28）、（2.04±0.40）、（1.73±0.36）mm。A组的渗入深度明显高于B、D组,其差异有统计学意义（P<0.05）。结论使用不同的方法预备根管去除玷污层,可以减少根管治疗后牙齿的冠渗漏。     

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??Objective    To study the effect of different irrigation regimens and methods of activation on smear layer removal in root canals. Methods    Thirty-two mandibular premolar roots were divided into 4 groups??with 8 teeth in each . In group A??the teeth were instrumented and irrigated by lateral opening syringe. In group B??irrigation was done using passive ultrasonic irrigation??PUI?? system. In group C RinsEndo root canal irrigation system was used and in group D??Vibringe sonic irrigation system. Scanning electron microscope evaluation was done for assessment of smear layer removal in the coronal??middle??and apical thirds. Results    In each group??there was a smear layer covering the dentinal tubule in apical thirds??and the score was higher than that in the coronal and middle ??P??0.05??. The scores of B??C and D groups were lower than those in group A??P??0.05??. Among A??B??C??D groups in the area of the root canal wall??difference of smear layer score was not statistically significant. Conclusion    Better removal of smear layer of the middle and apical thirds of root canal can be achieved by using RinsEndo??Vibringe and PUI system than by lateral opening syringe.     

Scanning electron microscope study on the efficacy of root canal wall debridement of hand versus Lightspeed instrumentation

AIM: The aim of this in vitro study was to compare the efficacy of root canal wall debridement following hand versus LightSpeed instrumentation. METHODOLOGY: Twenty recently extracted single-rooted teeth were paired and randomly placed into two treatment groups of 10 teeth each. In group 1, a step-back instrumentation without initial coronal flaring with stainless steel Hedstroem files was used; group 2 was instrumented with Ni-Ti LightSpeed instruments. Both groups had the same irrigation regimen: 2.5% NaOCl and a 15% EDTA solution. The teeth were then decoronated and each root split longitudinally into two halves to be examined using the scanning electron microscope (SEM). The presence of superficial debris and smear layer was evaluated by a standardized grading system, and the resulting scores submitted to nonparametric statistics. RESULTS: Under the conditions of this study, the removal of superficial debris was generally excellent with both canal preparation techniques. Both techniques resulted in variable presence of residual smear layer, with a canal wall covered by smear layer as the predominant characteristic. Generally, the amount of smear layer was greater in the apical than in the middle third of the root, however, this difference was statistically significant (P < 0.005) only in hand-instrumented teeth. The use of LightSpeed instruments was associated with significantly more (P < 0.05) smear layer presence in the middle region of the root when compared with hand instrumentation. In addition, less smear layer was present in the apical region following LightSpeed instrumentation than stainless steel hand files, but this difference was not statistically significant. Differences in debridement between the two halves of the same root were more evident with LightSpeed than manual instrumentation, however, there was no statistical significance. CONCLUSIONS: It may be inferred that the choice between hand and LightSpeed instrumentation should be based on factors other than the amount of root canal debridement, which does not vary significantly according to the instruments used.