03.机用根管预备后缩短乙二胺四乙酸的冲洗时间对玷污层清除的影响

根管预备中形成的玷污层约2μm厚,位于根管内壁表面并深入牙本质小管约40μm.去除玷污层有利于根管系统的良好封闭.研究发现,使用23号冲洗针,用10 mL 17%乙二胺四乙酸(ethylene diamine tetraacetic acid,EDTA)溶液和10 mL 5.25%NaClO溶液冲洗是去除玷污层的最有效方法;与17%EDTA溶液接触1～10min均能有效去除玷污层.     

根管治疗中应用Nd:YAG 激光的扫描电镜观察

目的 探讨Nd：YAG激光在根管治疗中的应用。方法 选用28个离体单根牙，随机分为4组。对照组不做处理。常规组进行根管扩大和根管冲洗，激光组经根管扩大后，用Nd：YAG激光1．5W，20pps分别照射15s和30s，并用扫描电镜观察。结果 激光照射15s组玷污层被去除，牙本质小管封闭和半封闭。激光照射30s组牙本质过分熔融，牙本质小管口开放。结论 Nd：YAG激光在根管治疗中的应用是可行的。     

MTAD作为根管冲洗剂的效果评价

目的探讨应用MTAD作为根管冲洗剂去除根管壁玷污层的效果,以及对根管充填后根尖微渗漏的影响。方法采集因正畸或牙周病拔除的前磨牙,截冠后统一工作长度16 mm,按照冲洗液使用的不同,随机分为A、B、C 3组,每组12颗。A:生理盐水;B:MTAD;C:5.25%NaClO+15%EDTA。采用机用Protaper镍钛根管锉进行根管机械预备,分别用相应冲洗液冲洗,根管预备后每组4颗牙齿用于制备扫描电镜标本,观察根管表面玷污层和牙本质小管暴露的情况。每组剩余8颗进行根管充填,1周后,采用液体转移法,测量各样本根管微渗漏。实验数值采用SPSS 19.0软件包进行分析。结果 A组沉积大量玷污层,牙本质小管被遮蔽,B、C组玷污层得到有效的清除,牙本质小管开放。根管充填后,A组和B组之间,A组和C组间的微渗漏值有统计学差异(P<0.05),B组合C组之间无统计学差异(P>0.05),其中A组的微渗漏值最大。结论 MTAD冲洗剂可以替代5.25%NaClO+15%EDTA联用,能有效地去除根管充填过程中产生的玷污层,增强根管充填后的根尖封闭性。     

Nd:YAG激光照射根管后的形态学观察

目的：了解感染根管管壁牙本质的病变特点，根管预备及Nd：YAG激光照射对感染根管的作用。方法：选用单根患牙60颗，随机分为5组：对照组（治疗前感染根管）、根管预备组（用手用器械根管预备）、3个激光组（在常规根管预备后，采用3种不同能量参数照射1min），做扫描电镜观察。结果：对照组：感染根管牙本质小管形态不规则，排列紊乱。根管预备组：能去除病变的牙本质层，形成玷污层。50mj 10Hz激光组不能封闭牙本质小管。100mj 10Hz、150mj 10Hz激光照射1min根管壁呈熔融状态，去除了玷污层，牙本质小管封闭和半封闭。结论：激光剂量在100mj 10Hz或在此以上时，能有效清洁根管壁玷污层和封闭牙本质小管。     

不同冲洗剂对桩道内壁牙本质形态的影响

目的:比较3种冲洗液5.25%NaClO溶液和15%EDTA溶液、0.2%的氯己定溶液对桩道内壁形态的影响。方法:筛选18颗新鲜拔出单根管前磨牙,在釉牙骨质界上2 mm处截冠,随机分成3组。常规根管充填、桩道预备后分别用A:蒸馏水(对照组)、B:5.25%NaClO溶液和15%EDTA溶液、C:0.2%的氯己定溶液冲洗桩道,将牙根纵向劈开。选取能够较好展示根管壁的一侧作为样本,扫描电子显微镜观察根中1/3的牙本质表面,按Gorman分类法记分,记录数据并统计分析。结果:A组玷污层较厚,有中等量杂质及碎屑残留,牙本质小管极少或不可见;B组清洁程度最高,玷污层极少,极少量杂质及碎屑残留,牙本质小管开口较清晰;C组有部分玷污层,少量杂质及碎屑残留,牙本质小管开口部分可见。各组差异有统计学意义(P<0.05)。结论:冲洗处理对桩道对牙本质表面有影响,应用5.25%NaClO溶液和15%EDTA溶液冲洗效果最好。     

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。     

XP-endo Finisher锉对根管内壁玷污层清除效果的体外研究

目的 评估XP-endo Finisher（XPF）锉与被动超声冲洗（PUI）对根管内壁玷污层的清除效果。方法 选择60颗离体单直根管下颌前磨牙,距根尖16 mm处截冠,采用S3镍钛锉预备到3S,根据终末处理方式不同将样本随机分成6组。A组：3 mL 3%次氯酸钠溶液联合XPF处理1 min;B组：3 mL 3%次氯酸钠溶液联合XPF处理1 min,再用4 mL 17%乙二胺四乙酸（EDTA）溶液冲洗1 min;C组：3 mL 3%次氯酸钠溶液联合PUI处理1 min;D组：3 mL 3%次氯酸钠溶液联合PUI处理1 min,再用4 mL 17%EDTA溶液冲洗1 min;E组：3 mL 3%次氯酸钠溶液30号侧方冲洗针冲洗1 min;F组：3 mL 3%次氯酸钠溶液30号侧方冲洗针冲洗1 min,再用4 mL 17%EDTA溶液冲洗1 min。采用扫描电子显微镜观察玷污层形态,并比较根尖1/3区、根中1/3区牙本质小管开口数。结果 A、C、E组实验样本整个根管壁都有玷污层覆盖,A组与C组牙本质小管开口数明显高于E组（P<0.05）,而A组与C组的差异无统计学意义（P>0.05）;F组根中区、B组和D组根尖区有少量玷污层覆盖,牙本质小管开放或半开放;F组根尖区可见玷污层,牙本质小管封闭或半封闭;B和D组根中区根管壁玷污层均被有效去除;在根尖1/3区和根中1/3区,B组与D组牙本质小管开口数高于其他4组（P<0.05）,而B组和D组间的差异无统计学意义（P>0.05）。结论 XPF锉对根管内壁玷污层的清洁效果与PUI无明显差异,可用于根管预备后提高根管清洁效果。     

Nd：YAG激光照射对根管壁的作用

目的：观察Nd:YAG激光对根管壁的作用。方法 选用25颗离体单根牙,随机分5组,对照组不做根管预备,常规组用K型根管锉扩大根管,激光3个组在常规根管预备后,激光工作条件为1．70W,20pps,分别照射15秒,30秒和60秒,并用扫描电镜观察。结果,激光照射15秒和30秒组根管壁呈熔融状态,去除了玷污层,牙本质小管封闭和半封闭,未见对牙体硬组织的损伤。激光60秒组对根管壁有过分熔融,形成裂而且不能完全封闭牙本质小管。结论 激光照射15秒和30秒能够清洁根管壁和封闭牙本质小管。     

脉冲Nd：YAG激光不同条件下照射牙根管壁的形态学观察

目的：观察不同条件下脉冲Nd:YAG激光照射牙根管壁后的清洁程度及管壁牙本质的超微结构改变。方法：14颗离体人上前牙，常规根管预备后，分为对照组和激光照射组，后者按不同的功率、频率及管壁加墨汁与否6种设定各2颗牙分别进行照射，然后各组标本扫描电镜下观察并记录。结果：（1）激光照射各组均较对照组根管壁玷污层减少，且随激光功率增大，管壁清洁度,管壁清洁度提高，管壁牙本质的超微结构变化增大。其中2W 20pps组管壁上无玷污层，根尖1／3区尚有牙本质熔融，沉积。3W20pps,4W 20pps组除上述变化外，根管壁牙本质熔融更为显著，并有程度不同的炭化和裂缝；（2）2W 15pps管壁清洁度较2W 20pps组低；（3）1W 20pps加墨汁后，根管清洁效果显著改善，并出现牙本质熔融，小管口封闭。结论：激光剂量在2W 20pps或在此以上时能有效去除根管壁玷污层，达到较理想的清洁效果，但只有较大剂量时才能熔融，封闭牙本质小管口；加墨汁能在低能量条件下显著增强激光作用效果。     

不同方法去除根管壁玷污层效果的实验研究

目的:评价4种不同方法去除根管壁玷污层的能力。方法:将40颗离体牙随机分为4组进行根管预备,使用不同方法去除玷污层,分别为:A组H2O2和生理盐水,B组EDTA凝胶和5.25%的NaClO,C组超声波,D组超声波联合5.25%NaClO+EDTA。将处理后的样本纵剖开,扫描电镜观察4组根管壁的界面,比较3个不同部位玷污层的去除情况、根管壁的清洁程度、牙本质小管的开放程度及腐蚀程度。结果:对照组(A组)根管壁被玷污层覆盖,实验组(B、C、D组)根管壁玷污层去除明显,B、C、D组与A组间冠1/3、中1/3、尖1/3玷污层评分差异有显著性(P<0.05);3个实验组间冠1/3、中1/3、尖1/3玷污层评分差异无显著性(P>0.05);D组冠1/3和中1/3可见到根管壁有不同程度的腐蚀。结论:NaClO与EDTA,超声波以及超声联合NaClO与EDTA均可有效地去除根管壁上的玷污层,但超声联合NaClO与EDTA能造成牙本质小管的腐蚀。     

A comparative study of the removal of smear layer by three endodontic irrigants and two types of laser

AIM: The effects of three endodontic irrigants and two types of laser on a smear layer created by hand instrumentation were evaluated in vitro in the middle and apical thirds of root canals. METHODOLOGY: Sixty human mature extracted mandibular premolar teeth with a single root canal and a closed apex were distributed randomly into five groups of 12 teeth each. Whilst cleaning and shaping up to a size 60 master apical file with a step-back technique, the root canals were irrigated with 3 mL of 5.25% NaOCL and 3% H2O2, alternately, between each file size. Group 1 (G1) were control specimens that were irrigated with a final flush of 17% EDTA. The teeth in group 2 (G2) were irrigated with a final flush of 6% phosphoric acid, and group 3 (G3) with 6% citric acid. In the specimens of group 4 (G4) the root canals were irradiated with a carbon dioxide (CO2) laser, and specimens of group 5 (G5) were irradiated using an Er:YAG laser. The teeth were split longitudinally and prepared for examination by scanning electron microscopy. RESULTS: Control specimens (G1) showed clean root-canal walls with open dentinal tubules in the middle one-third, but in some specimens thick smear layer was observed in the apical one-third. Specimens irrigated with a final flush of 6% phosphoric acid (G2) or 6% citric acid (G3) were cleaner than with 17% EDTA, showing very clean root canal surfaces in the middle one-third but in the apical one-third the smear layer was not completely removed, especially at the openings of the dentinal tubules. The specimens irradiated with the CO2 laser (G4) showed clean root-canal walls with the smear layer absent, charred, melted, recrystallized and glazed in both middle and apical thirds. The root-canal walls of the specimens irradiated with the Er:YAG laser (G5) revealed an absent smear layer with open dentinal tubules in the middle and apical thirds. Statistical analysis showed no significant difference in the cleanliness of root-canal wall between G1 and G2, and G1 and G3. However, there were statistically significant differences (P < 0.01) between G1 and G4, and G1 and G5 in the cleanliness of the middle and apical one-thirds of the root canals. CONCLUSIONS: Irrigation with 17% EDTA, 6% phosphoric acid and 6% citric acid did not remove all the smear layer from the root-canal system. In addition, these acidic solutions demineralized the interbular dentine around tabular openings, which became enlarged. The CO2 laser was useful in removing and melting the smear layer on the instrumented root-canal walls and the Er:YAG laser was the most effective in removing the smear layer from the root-canal wall.     

Effects of Nd: YAG laser irradiation on the root canal wall dentin of human teeth: a SEM study

The purpose of this study was to observe the morphological and histological changes on the root canal walls after Nd:YAG laser application. Twenty vital, recently extracted single-rooted human teeth were used for this study. Root canals were cleaned and shaped by a conventional step-back technique--by means of k files up to a 20 k-file type at working length--and subsequently shaped by Ni-Ti root-canal rotary instrumentation up to 30/06 and irrigated with 2.5% hypochlorite solution. Ten teeth (control group) were left unlased, while the other ten teeth were irradiated with Nd:YAG laser by means of a 320 microns fibre inserted in the root canal at 1 mm from the apex with a power of 1.5 Watt and a frequency of 15 pps for five seconds in retraction with rotating movements. The control specimen showed debris and smear layer on the root canal surface obscuring the dentin tubules. The root canal walls irradiated with Nd:YAG laser showed a clear glazed surface, some open dentinal tubules and some surface craters with cracks. Such results confirm that smear layer and debris are removable with Nd:YAG laser, however clearing all root canal walls is still difficult and, if the energy level and duration of application are inadequate, a certain degree of thermal damage and morphological changes in dentin structure are observable.     

A new solution for the removal of the smear layer

Various organic acids, ultrasonic instruments, and lasers have been used to remove the smear layer from the surface of instrumented root canals. The purpose of this study was to investigate the effect of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) as a final rinse on the surface of instrumented root canals. Forty-eight extracted maxillary and mandibular single-rooted human teeth were prepared by using a combination of passive step-back and rotary 0.04 taper nickel-titanium files. Sterile distilled water or 5.25% sodium hypochlorite was used as intracanal irrigant. The canals were then treated with 5 ml of one of the following solutions as a final rinse: sterile distilled water, 5.25% sodium hypochlorite, 17% EDTA, or a new solution, MTAD. The presence or absence of smear layer and the amount of erosion on the surface of the root canal walls at the coronal, middle, and apical portion of each canal were examined under a scanning electron microscope. The results show that MTAD is an effective solution for the removal of the smear layer and does not significantly change the structure of the dentinal tubules when canals are irrigated with sodium hypochlorite and followed with a final rinse of MTAD.     

5种冲洗剂组合对前牙直根管清洁效果的比较

目的：比较5种冲洗剂组合对前牙直根管的清洁效果。方法：25颗离体直根管前牙,随机分为5组,不锈钢K锉常规法预备根管．应用5种冲洗剂组合进行冲洗。第1组：根管器械预备期间和预备结束后依次用1％NaOCl和3％H2O2冲洗;第2组：根管器械预备期间用1％NaOCl冲洗,预备结束后用17％EDTA冲洗;第3组：根管器械预备期间和预备结束后依次用1％NaOCl和17％EDTA冲洗：第4组：根管器械预备期间依次用17％EDTA和1％NaOCl冲洗,器械预备结束后用17％EDTA冲洗;第5组：根管器械预备期间依次用17％EDTA、1％Triton X-100(表面活性剂)和1％NaOCl冲洗．器械预备结束后用17％EDTA冲洗。每组冲洗剂剂量和冲洗时间均为22ml和7min。将牙纵劈后进行扫描电镜观察。结果：第1组,根管壁上见典型玷污层结构和大量杂质和残屑。第2组在根管冠、中1／3能部分去除玷污层．根尖1／3残留大量玷污层。第3组虽然能有效去除玷污层．但会引起牙本质小管中度腐蚀。第5组在根管冠、中1／3能部分去除玷污层,但根管壁上黏着大量杂质和残屑．此外还存在重度腐蚀现象。第4组根管清洁效果最好,且对牙本质小管无腐蚀性。结论：在严格控制冲洗时间和顺序的情况下,联合应用17％EDTA和1％NaOCl能有效去除玷污层．且不会腐蚀牙本质小管。     

Effect of Er:YAG laser treatment on the root canal walls of human teeth: an SEM study

Abstract— The purposes of the study were to observe the morphological changes on root canal walls after instrumentation and irrigation, and assess the efficacy of conventional cleansing procedures and the effectiveness of Er:YAG laser in removing debris and smear layer from the root canal walls. Thirty-six endodontically treated human mandibular incisor teeth with single root canals were bisected longitudinally and divided into three groups of 12 teeth. Group 1 (Gl) was left unlased as a control. The teeth of group 2 (G2) and group 3 (G3) were irradiated by Er:YAG laser (laser parameters were set at 1 W, 100 mJ/pulse and 10 Hz) for 3 s and 5 s. The teeth were prepared for scanning electron microscope study. Control specimens showed debris and heavy smear layer obscuring the dentinal tubules at all levels in the canals. The root canal walls irradiated by Er:YAG laser were free of debris, with an evaporated smear layer and open dentinal tubules. These results suggested that Er:YAG laser irradiation had an efficient cleaning effect on the prepared root canal walls.     

NaOCl and EDTA irrigating solutions for endodontics: SEM findings.

Premolars roots of humans were manually instrumented with K-type files and irrigated with different solutions to evaluate the rate of cleaning of endodontic surface. Root canals irrigated with 0.9% saline solution or H2O2 (10 volumes) showed the presence of predentin and amorphous smear layer. Thick smear layer was always present on endodontic walls rinsed with 5% solution of NaOCl. Specimens treated with 0.2% solution of EDTA showed partially clean dentinal tubules orifices and remnants of a thin smear layer. Occasional uninstrumented areas of the same roots presented smear layer remnants and predentin with calcified bacteria. The root canals irrigated with NaOCl and EDTA solutions alternated after each instrument showed at the dentin surface thick smear layer: only few dentinal tubules orifices were visible. Endodontic surface of root canals irrigated with NaOCl during instrumentation and finally rinsed with EDTA solutions showed the most homogeneous ultrastructural pictures: partially clean dentinal orifices were detectable in the whole canals.     

The adaptation of mechanically softened gutta-percha to the canal walls in the presence or absence of smear layer: a scanning electron microscopic study

The objective of this study was to compare the adaptation of mechanically softened gutta-percha to the root canal wall in the presence and absence of smear layer. The root canals of 20 freshly extracted human maxillary incisors were cleaned and shaped. Prior to obturation, 10 root canals were irrigated with 20 ml of 50% citric acid followed by 20 ml of 5.25% sodium hypochlorite. All canals were obturated with mechanical compaction of gutta-percha and AH-26 sealer. After 72h, each tooth was fractured in half. Scanning electron microscopy demonstrated that the sealer had formed a continuous layer in contact with the canal walls, becoming progressively thinner towards the apex. The sealer pentrated into the dentinal tubules along with projections of gutta-percha only in those teeth without smear layer.