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…     

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。     

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。     

三种手用器械对弯曲根管成形能力的比较研究

GT器械为大锥度设计的非ISO类镍钛器械，预备弯曲根管能维持根管走向，形成连续流畅的锥形形态。我们比较了采用平衡力技术的GT手用锉和NiTiflex K锉及采用逐步后退技术的不锈钢(stainless steel，SS)K锉定位弯曲根管中心及去除牙本质的能力，以期评价其根管预备效果。     

3种根管扩大器械预备弯曲根管的体外实验

目的：运用手持根管扩大器械预备弯曲根管，观察根尖偏移发生率，方法：选取57颗弯曲单根管离体前磨牙作为研究对象，随机分成三组，A组19颗用Lightspeed镍钛合金器械预备根管，B组运用K锉，C组运用H锉，C组运用H锉，预备方法均为逐步后退技术，使用双曝光技术判断根尖偏移情况，结论：A组中有19％的根管发生了根尖偏移，B组中有82％发生了根尖偏,C且中有88％发生了根尖偏移，结论：运用Lightspeed镍钛器械预备弯根管可以减少根尖偏移的发生。     

3种新型镍钛机动器械对椭圆形根管成形能力的效果比较

目的:比较3种新型镍钛根管预备系统对椭圆形根管成形能力的差异。方法:收集45个具有椭圆形单根管的下颌前牙,分别用自调节根管锉(Self-adjusting File,SAF)、Pro Taper Universal和Pro Taper Next系统进行根管预备(n=15),在根管预备前后分别进行显微CT扫描,评价各组器械预备根管后牙本质面积增加量、去除牙本质体积量和未接触到的根管面积百分比。结果:SAF未接触到的根管面积百分比较ProTaper Next和Pro Taper Universal组低(P<0.05);而3组之间的牙本质面积增加量和去除牙本质量无统计学差异(P>0.05)。结论:SAF预备椭圆形根管时去除牙本质均匀,对椭圆形根管成形能力的效果更佳。     

根管偏移对充填材料封闭根管能力的影响

目的：研究弯曲根管预备后的根管偏移对充填材料封闭根管能力的影响。方法：选取73颗下颌单根管前磨牙作为研究对象，其中弯根管牙46颗，直根管牙27颗，A组23颗弯根管牙用Lightspeed器械预备根管，B组23颗弯根管牙，C组17颗直根管牙以及对照组牙用K锉预备根管，预备方法为逐步后退技术，使用双曝光X线技术和Ehrlich法测量根管偏移指数（AT1）的大小，使用侧向加压技术充填所有根管后，用流体传输模型测量每个根管内微渗漏的量，结果：A组中有19％的根管发生根管偏移，B组中有85％的根管发生根管偏移，两组之间AI1的大小有高度显著性差异，当ATI大于0．3nm，时，根管内微渗漏的发生率明显增加，结论：弯曲根管顶备中出现的根管偏移会削弱充填材料封闭根管的效果。     

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。     

超声根管预备对C形根管治疗的临床疗效观察

目的观察超声根管预备在C形根管治疗中的临床疗效。方法将178颗患牙随机分为2组,分别用手用K锉行逐步后退法根管预备和超声锉根管预备,冷侧压充填根管2年后观察其疗效。结果超声组明显优于手用K锉组。结论超声在根管预备方面有良好的疗效,应用于C形根管等复杂根管的治疗,省力、质量好。     

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.     

Microtensile bond strength to root canal vs pulp chamber dentin: effect of bonding strategies

PURPOSE: The aim of this in vitro study was to compare the microtensile bond strength (MTBS) between root canal and pulp chamber dentin with two bonding strategies (self-etching primer and total-etch technique). MATERIALS AND METHODS: The pulp chamber of four human canines was accessed and the pulp chamber and root canal prepared with spiral drills. The teeth were cut into halves parallel to the long axis of the tooth and randomly assigned to two groups: Clearfil SE Bond + AP-X(SE) (Kuraray) and SingleBond + Filtek Z250(SB) (3M ESPE). After 24 h in water storage, the specimens were cut perpendicular to the root into 1.0-mm slices with a low-speed diamond saw. Specimens were trimmed to obtain hourglass shapes with a bond area of 1.0 mm2 (n = 12). Three specimens were obtained from the cervical root canal dentin (R) and from the coronal pulp chamber dentin (C). The MTBS was measured in a Bencor device with an Instron machine at a crosshead speed of 0.5 mm/min. The data was analyzed with two-way ANOVA and Tukey LSD post hoc (p < 0.05). RESULTS: MTBS in MPa (mean +/- SD) were: SB.C = 25.3 (+/-6.5)a; SB.R = 16.9 (+/-6.0)b; SE.C = 16.9 (+/-3.4)b; SE.R = 16.8 (+/-5.3)b. Means with the same letter are not statistically different at p < 0.05. When data were pooled for "dentin region", coronal pulp chamber dentin resulted in statistically higher bond strengths than root canal dentin (p < 0.013). CONCLUSION: Bonding to pulp chamber dentin seems to be more predictable than to root canal dentin. In the former region, the total-etch technique may result in a higher bond strength.     

Impact of the quality of coronal restoration versus the quality of root canal fillings on success of root canal treatment: a systematic review and meta-analysis

Introduction

Thorough cleaning and shaping of root canals are essential for periapical healing. Restoration of endodontically treated teeth is also required for them to function and prevent coronal leakage. This study compared the impact of the quality of root canal treatment versus the quality of coronal restoration in treatment outcomes.

Methods

Literature search was conducted using the search terms “coronal restoration,” “root canal,” “periapical status,” and “quality.” Articles that evaluated the effect of the quality of root filling and coronal restoration or both on the success of root canal treatment were selected. Nine articles were identified and were reviewed by 3 investigators. Data were collected based on predetermined criteria. Percentages of teeth without apical periodontitis were recorded for each category: adequate root canal treatment (AE), inadequate root canal treatment (IE), adequate restoration (AR), and inadequate restoration (IR). Data were analyzed using meta-analysis for odds ratios (ORs).

Results

After adjusting for significant covariates to reduce heterogeneity, the results were combined to obtain pooled estimates of the common OR for the comparison of AR/AE versus AR/IE (OR = 2.734; 95% confidence interval [CI], 2.61-2.88; P < .001) and AR/AE versus IR/AE (OR = 2.808; 95% CI, 2.64−2.97; P < .001).

Conclusions

On the basis of the current best available evidence, the odds for healing of apical periodontitis increase with both adequate root canal treatment and adequate restorative treatment. Although poorer clinical outcomes may be expected with adequate root filling-inadequate coronal restoration and inadequate root filling-adequate coronal restoration, there is no significant difference in the odds of healing between these 2 combinations.     

口腔医学生临床前离体牙及人工根管根管治疗教学研究

目的：通过离体牙、人工根管培养实习医生了解并掌握根管治疗的标准程序和方法。方法：选择正畸患者拔除离体牙36颗、牙髓病及牙周病拔除离体牙42颗,人工根管4颗,分组采用常规改良逐步后退法、冠向逐步深入法进行根管处理、预备及充填,观察实习医生根管治疗掌握情况及模拟治疗效果。结果：离体牙采用改良逐步后退法时,前牙根管治疗成功率〉前磨牙〉磨牙（P〈0.05）;离体牙磨牙组中,采用冠向逐步深入法成功率高于逐步后退法（P〈0.01）。结论：采用人工根管可以直观的辅助实习医生体会弯曲根管的治疗,结合离体牙进行根管治疗训练可以提高加深实习医生对根管解剖结构、不同根管治疗方法的了解,对于实习医生临床前培养有明显效果。     

Ultramicroscopic study of the interface and sealing ability of four root canal obturation methods: Resilon versus gutta‐percha

Recently, filling materials have been introduced based on the dentine adhesion technologies used in conservative dentistry in an attempt to seal the root canal more effectively. The purpose of this study was to investigate the interface between the canal and root‐filling material. Sealing ability of four root canal obturation methods was analysed by means of scanning electron microscopy. Extracted single‐rooted teeth were endodontically treated and filled with gutta‐percha/Pulp Canal Sealer using the Thermafil (TH) technique, gutta‐percha/Pulp Canal Sealer using the System B (SB) technique, Resilon points/RealSeal (RS) and RealSeal 1/RealSeal (RS1). Specimen interfaces were analysed using field‐emission scanning electron microscopy. The adhesive groups RS and RS1, formed hybrid layers but showed areas of separation (gaps) similar to those in the conventional obturation groups. The RS and RS1 groups showed less separation in the coronal third, but the separation was similar to that in the TH and SB groups in the middle and apical thirds. The sealing ability of Resilon is not superior to that of existing materials.     

The Effect of Root Preparation Technique and Instrumentation Length on the Development of Apical Root Cracks

The purpose of this study was to compare the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Forty extracted mandibular premolars with straight roots were randomly selected and mounted on resin blocks with simulated periodontal ligaments, and the apex was exposed. The teeth were divided into four groups of 10 teeth each for different canal preparation techniques and instrumentation lengths: group A: step-back preparation (SB) with stainless steel files (SF) using root canal length (RCL) to guide instrumentation length; group B: SB using RCL ? 1 mm; group C: crown-down preparation (CD) with Profile using RCL; and group D: CD with PF using RCL ? 1 mm. Digital images of the instrumentation sequence were compared for each tooth. Statistical analysis revealed a significant effect of instrumentation length (p < 0.05) but no significant effect of preparation technique (p > 0.05) on the development of apical cracks.     

Long-term durability of root-end sealing with 4-MEtA/MMA-TBB resin

The purpose of this study was to compare root-end sealing using 4-META/MMA-TBB resin with that using conventional retrograde root filling technique, and thereby determine if 4-META/MMA-TBB resin offers long-term prevention against dye leakage from the root canal of human teeth. Thirty-five teeth had the apical 2.5 mm of the root resected. In the Sealing (SB) group, 4-META/MMA-TBB resin was applied to the resected surface. In the Filling (Am and EBA) groups, a root-end cavity was prepared and retrofilled with high copper amalgam alloy or reinforced zinc oxide-eugenol cement. Root canals were filled with methylene blue dye solution. Then, dye leakage outside the root canal was measured for 50 weeks. The integrated amount of leakage in SB group was significantly lower than those in Am group (p < 0.05) and EBA group (p < 0.05). Therefore, it can be concluded that root-end sealing using 4-META/MMA-TBB resin resulted in better, long-term sealing than conventional retrograde root filling.     

即刻桩腔预备对三种根管预备方法预备的直根管根尖封闭性的影响

目的 研究三种不同根管预备方法根管预备、根管充填后即刺桩腔预备对直根管根尖封闭性的影响.方法 离体直单根管上前牙124个,其中120个随机平均分为3组(n=40),A组:不锈钢根管锉常规法;B组:G 型钻根管冠部预处理 不锈钢根管锉常规法;C组:手用Pr01raper镍钛根管锉冠向下法,刺余4个随机平均分为阴性对照组和阳性对照组.所有根管均用侧方加压法充填,即刻手持垂直加压器去除部分充填材料,然后P型钻桩腔预备.用染料渗透法评价各组根尖封闭能力.结果 B组G型钻根管冠部预处理 不锈钢根管锉常规法预备的根管和C组手用ProTaper镍钛根管锉冠向下法预备的根管即刻桩腔预备后,其根尖微渗漏较A组常规法预备的轻(P<0.05).结论 大锥度根管预备,根管充填后即刻桩腔预备的根尖封闭性较好.     

Comparison of mechanical and standard hand instrumentation techniques in curved root canals

The original and postinstrumentation shapes of the mesial root canal system of 12 mandibular molars were compared after being instrumented with a mechanical handpiece and a hand instrumentation technique. Area of dentin removed and amount and direction of transportation were evaluated in relation to degree of root canal curvature. Pre- and postinstrumentation measurements were taken of the root canal system in the cervical, middle, and apical thirds. The mechanical handpiece removed dentin and transported the root canal more than the hand instrumentation in the cervical and apical thirds. Both techniques transported to the distal in the cervical third and to the mesial in the apical third. In the middle third, the mechanical handpiece transported more to the mesial and the hand instrumentation more to the distal. Degree of root canal curvature had no influence on the amount of dentin removed or transportation of the root canal.     

Quantification of mechanical versus ultrasonic technique in root canal preparation

The previous investigations of the cutting efficacy of the paracanal dentine with different endodontic instruments have not quantified the amount of the tissue removed. The purpose of this study was to compare the effectiveness of various mechanical canal instrumentations with ultrasonic technique by measuring the weight loss of the root dentine. The investigation concerned 60 single-canal roots of freshly extracted human teeth. Each canal was primarily prepared with Beutel rock reamers, size 3, with penetration to the apex. After desiccation in the thermostat at 60 degrees C for 65 hours, roots were weighed using an electronic scale (Mettler, AE-163, West Germany) with a precision of 10(-4) grams. Samples were devided into six groups according to the endodontic instrument: (1)K-tupbe reamers, (2)K-files, (3) Hedstroem files, (4) giromatic cleansers, (5) giromatic files, (6) ultrasonic files. After having been prepared the root canal was thoroughly irrigated with 4 ml saline, redesiccated and reweighed. Ultrasonic instrumentation was the most effective in removing the root canal dentine compared with all mechanical techniques (t-test; p less than 0.005). The smallest amount of root canal dentine was removed by giro-files. This was statistically significant compared with K-files, giro-files and ultrasonic files. There was no significant difference among the other mechanical instruments used in this study.     

A comparison of dentine removal using safety or conventional Hedstrom files

Abstract Mandibular molars (n=20) were divided and the mesial roots mounted in an acrylic mould which allowed them to be removed, sectioned horizontally and then reassembled. The furcal root canal wall thickness 7 mm from the apex was measured prior to instrumentation. The roots were allocated to two groups (n=10). One group was instrumented using the step back technique with safety Hedstroms in one canal and conventional Hedstrom files in the other canal. The second group was instrumented using a crown down approach (using files and Gates Glidden drills to provide early radicular access). The furcal root canal wall thickness was then remeasured and the amount of dentine removed calculated. The results showed that the safetv Hedstrom file removed less dentine from the furcal region of the canal compared to the conventional Hedstrom file. This however was not statistically significant (Paired t test, n=10, p>0.05). The amount of dentine removed using the crown down technique was significantly greater than that using the step back technique (Two sample t, n = 20, p<0.01). In conclusion, less dentine was removed from the furcal region with safety Hedstrom files compared to conventional Hedstrom files; however, Gates Glidden drills removed more dentine than either type of hand file.