根管内Ca(OH)2去除效果对根尖封闭性能影响的研究

目的:研究不同冲洗方法对根管内氢氧化钙封药的去除效果及残留药物对根尖封闭性能的影响.方法:200 颗离体单根管前磨牙,根管预备后随机分为A、B 2 个实验组(每组96 颗,剩余8 颗为对照组),分别水调氢氧化钙和成品氢氧化钙制剂Multi- Cal根管内封药.7 d后,根据冲洗方法不同将A、B 2 组分别均分为6 组,去除氢氧化钙.每组随机选8 颗牙扫描电子显微镜(SEM)观察;剩余8 颗与对照组,采用冷牙胶侧方加压法根管充填后,进行染料渗透实验.结果:SEM观测显示,相同冲洗条件下,不同剂型氢氧化钙的去除情况无统计学差异(P>0.05).在其他条件相同时,超声根管冲洗组去除效果好于注射器冲洗组,有统计学差异(P<0.05);次氯酸钠与EDTA联合应用组的效果最好,单独使用次氯酸钠组的效果次之,使用蒸馏水组的效果最差,有统计学差异(P<0.05).染料渗透实验结果无统计学差异(P>0.05).结论:超声根管冲洗配合次氯酸钠与EDTA,去除根管内氢氧化钙效果最好;无论哪种方法,均无法完全去除根管内的氢氧化钙封药,但残留的氢氧化钙对根管充填短期内的封闭性能无明显影响.     

冲洗液对超声根管预备抗菌效果的影响

目的研究生理盐水、EDTA、次氯酸钠、口泰与超声波联合应用杀灭感染根管内厌氧菌的效果。方法将100例慢性根尖周炎患者共100颗患牙随机分为常规组、生理盐水组、EDTA组、次氯酸钠组、口泰组5组,每组各20颗患牙,常规组用常规法手持器械根管预备并分别用3%双氧水和生理盐水常规针筒式冲洗根管,后四组均用超声法进行根管预备并分别以生理盐水、EDTA、次氯酸钠、口泰作为超声冲洗液,根管预备前后分别取样进行厌氧培养。结果次氯酸钠组和口泰组其厌氧菌减少程度均显著大于生理盐水组(P<0.01),明显大于EDTA组(P<0.05);生理盐水组和EDTA组之间其厌氧菌的减少程度无显著性差异(P>0.05);次氯酸钠组和口泰组之间其厌氧菌减少程度无显著性差异(P>0.05)。结论口泰与超声波联合应用可有效杀灭感染根管内厌氧菌,其抗菌效果与次氯酸钠相近似。     

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。     

比较不同冲洗液对根管内氢氧化钙的清除效果及根管牙本质显微硬度的影响

目的:比较5种不同根管冲洗液对根管内氢氧化钙(CH)的清除效果及对牙本质显微硬度的影响。方法:在70颗单根管离体牙的根管壁上制备凹沟,10颗牙齿作为阴性对照组不导入CH糊剂,60颗牙齿导入CH糊剂,封药1周。1周后,10颗牙齿作为阳性对照组不去除CH糊剂,其余50颗牙齿根据清除氢氧化钙所使用的冲洗液不同随机分成5组(n=10),体视显微镜和SEM观察CH残余量,显微硬度计测试根管壁显微硬度。结果:10%柠檬酸、17%乙二胺四乙酸(EDTA)及1 g/L银杏叶提取物(EGb)溶液对CH的清除效果优于蒸馏水和2.5%NaClO溶液(P<0.05)。阴性对照组显微硬度值大于其余各组(P<0.05),其他组间比较无明显差异(P>0.05)。结论:5种冲洗液均不能完全清除根管内CH,但柠檬酸、EDTA及EGb溶液清除效果较好。CH封药1周降低根管牙本质显微硬度,冲洗液则无明显影响。     

不同根管冲洗液和冲洗方法对粪肠球菌清除作用的体外研究

目的 比较不同冲洗液和冲洗方法对根管内粪肠球菌的清除效果。方法 建立120颗人完整单根管前磨牙粪肠球菌感染根管模型,随机分组,分别采用不同冲洗液(0.9% NaCl,0.5% NaClO,3% NaClO)及冲洗方法(注射针头冲洗,超声荡洗,RinsEndo系统处理,超声荡洗协同RinsEndo系统联用)进行根管清理。无菌吸潮纸尖取样,平板菌落计数法计算CFU值,计算细菌清除率,运用SPSS 22.0软件进行统计分析,P<0.05时差异具有统计学意义。结果 使用0.9% NaCl及0.5% NaClO冲洗液时,注射针头冲洗组细菌清除率明显低于超声荡洗及RinsEndo系统处理组(P<0.001);使用3% NaClO冲洗液的各组不同的冲洗方法,细菌清除率的差异无统计学意义(P=0.556)。而无论采用哪种冲洗方法,3% NaClO溶液的细菌清除效果均优于0.5% NaClO溶液和0.9% NaCl溶液(P<0.001)。结论 不同根管冲洗液在一定程度上会影响根管冲洗方法对根管内粪肠球菌的清除效果。     

比较不同冲洗技术去除老年人根管玷污层效果

目的：应用60℃NaOCl配合不同的冲洗技术对老年人离体牙根管进行冲洗,评估玷污层的清除效果。方法：将40颗取自老年人(60周岁以上)的完整上颌离体前牙,应用60℃NaOCl进行根管冲洗。按照不同的冲洗技术随机分为4组(n=10)：侧方开口冲洗器组、被动超声组(PUI组)、EndoActivator组、对照组,并评估玷污层清除情况。结果：比较4组不同的冲洗技术对老年人根管玷污层的去除情况：EndoActivator组、PUI组和对照组之间差异无统计学意义,且优于侧方开口冲洗器组(P<0.05)。分别比较4组组内不同的根管水平玷污层的去除情况：各组根上1/3优于根中1/3,根中1/3优于根尖1/3(P<0.05)。结论：60℃3%NaOCl作为基础冲洗液,17%EDTA作为最终冲洗液,不使用任何冲洗设备与辅助被动超声或EndoActivator对老年人根管进行冲洗玷污层清除效果相似,且均优于侧方开口冲洗器。     

复方冰硼冲洗液用于根管冲洗的清洁性实验研究

目的：评价复方冰硼冲洗液用于根管冲洗的清洁性。方法：收集40个新鲜拔除的单根管前磨牙,随机分为4组,每组10个。采用不锈钢K锉和逐步深入预备技术预备根管,分别使用4组冲洗液进行根管冲洗。Ⅰ组为5mL复方冰硼冲洗液;Ⅱ组为2.5mL 5.25%次氯酸钠溶液（NaOCl）＋2.5mL 17%乙二胺四乙酸溶液（EDTA）;Ⅲ组为2.5mL 3%双氧水＋2.5mL 0.9%生理盐水;Ⅳ组为5mL 0.9%生理盐水。最后用3mL生理盐水冲洗根管。采用数码照相机照相和扫描电镜观察,分别比较根尖1/3区和根中1/3区根管内的碎屑百分数和牙本质小管开口数。结果：在根尖1/3区,Ⅳ组碎屑百分数明显高于其他3组,Ⅳ组牙本质小管开口数明显少于其他3组（P〈0.05）。在根中1/3区,Ⅳ组的碎屑百分数明显高于Ⅱ组,Ⅰ、Ⅱ组牙本质小管开口数明显多于Ⅲ、Ⅳ组（P〈0.05）。结论：Ⅰ、Ⅱ、Ⅲ组的根管冲洗效果好于Ⅳ组,冲洗液的化学特性非常重要。冲洗液的清洁性排序为：NaOCl组、复方冰硼冲洗液组、双氧水组、生理盐水组。复方冰硼冲洗液被认为是可能用于根管冲洗的中药冲洗液。     

根尖预备尺寸对玷污层清除效果的比较研究

目的:比较5种不同根尖预备方案对根管玷污层的清除效果。方法:将50颗单根管上颌离体前牙随机分为5组,A组:采用机动ProTaper系统将根尖预备至25^#(F2),配合次氯酸钠+EDTA冲洗;B组:根尖预备至30^#(F3),预备及冲洗方法同A组;C组:采用机动ProTaper系统将根尖预备至F3,后用不锈钢K锉预备根尖至35^#,冲洗同A组;D组:采用机动ProTaper系统将根尖预备至F3,后用不锈钢K锉预备根尖至40^#,冲洗同A组;E组:根管预备同D组,冲洗用蒸馏水。利用热场发射扫描电子显微镜,评估玷污层清除情况。结果:B组、C组和D组均明显优于A组 (P<0.05);A组、B组、C组和D组明显优于对照E组(P<0.05)。结论:机动ProTaper将根管预备至30^#,可使足量的冲洗液渗入根尖1/3区,有效去除玷污层及碎屑。     

超声冲洗用于慢性牙髓炎一次法根管治疗术的临床评价

目的 评价根管超声冲洗技术对成人磨牙慢性牙髓炎一次法根管治疗术短期疗效的影响。方法 168 颗患牙按掷硬币的方法分为超声冲洗组86 颗和常规组82 颗,局麻下开髓、拔髓和根管预备,根管充填前常规组用2 mL 5.25% 的次氯酸钠溶液冲洗;超声冲洗组用2ml5.25% 次氯酸钠溶液注入根管,15号超声锉荡洗2min,期间不断补充新鲜液体。2组最后均使用17% EDTA 冲洗,吸干热牙胶垂直加压充填根管,窝洞暂封。3 天后复诊完成冠部充填。治疗后观察根管充填质量及侧枝根管充填情况、3天内疼痛发生情况以及1年后的治疗疗效。结果 超声组术后即刻侧支根管充填率提高,两组差异有统计学意义(P<0.05);根管充填后3 天内超声组疼痛发生率明显低于常规组(P<0.05);2 组1 年后疗效差异无统计学意义(P>0.05)。结论 超声冲洗能短期内降低术后疼痛发生率,提高侧支根管充填率,有很好的临床应用效果。     

二氧化氯冲洗根管清洁效果的扫描电镜观察

目的:评价二氧化氯(ClO2)用于根管冲洗的清洁效果.方法:选择30个离体单根管前磨牙,截去牙冠后随机平分成6组(SA、SB、SC、UA、UB、UC),采用逐步后退法进行根管预备,前3组用注射器冲洗根管,冲洗剂分别为3%H2O2 0.9%NaCl、1%次氯酸钠(NaClO)和0.1%ClO2;后3组用超声波冲洗,冲洗剂分别用蒸馏水、1%NaClO和0.1%ClO2.完成根管预备后纵行劈开牙根,扫描电镜观察,记录电镜照片上根管颈1/3、中1/3、尖1/3各部位的碎屑和玷污层情况,进行统计学分析.结果:使用注射器冲洗者,碎屑和玷污层记分SC组均明显低于SA组(P＜0.05),与SB组无显著性差异(p＞0.05);用超声波冲洗者,碎屑记分3组之间无显著性差异(P＞0.05),玷污层记分UC组显著低于UA组(p＜0.05),与UB组无显著性差异(P＞0.05).结论:0.1%ClO2可用于根管冲洗,对碎屑和玷污层的清除效果优于3%H2O2 0.9%NaCl,与1%NaClO无明显不同,联合超声波冲洗效果更好.     

Effectiveness of oxidative potential water as a root canal irrigant

AIM: The aim of this study was to evaluate the effectiveness of oxidative potential water (OPW) as an irrigant, based on its ability to remove the smear layer and/or debris from instrumented root canals. METHODOLOGY: One hundred and twenty root canals from extracted human maxillary incisors were instrumented using a conventional step-back technique with irrigation from sodium hypochlorite (NaOCl) or oxidative potential water (OPW). After instrumentation, the canals were irrigated by syringe or ultrasound using 15% EDTA or OPW as an irrigant. The volume of each irrigant used for syringe irrigation was 10, 20, and 30 mL, respectively, whilst the duration for ultrasonic irrigation was 1, 3, and 5 min, respectively. After irrigation, each root was split longitudinally in two with cutting pliers, and the specimens were prepared for SEM observation. The presence of debris and smear layer on each canal wall was assessed using a three-point scale for each parameter. RESULTS: Smear layer was effectively removed with EDTA both introduced via syringe and via ultrasonic irrigation. A similar effect was observed with OPW via syringe irrigation following instrumentation with 5% NaOCl. The canal walls in any of these cases showed open and patent dentinal tubules following smear layer removal. Some specimens irrigated with EDTA exhibited the effect of demineralization on the dentine resulting in funnelling of tubule orifices. Syringe irrigation was more effective in smear layer removal, except for ultrasonic irrigation with 15% EDTA, whilst ultrasonic irrigation was more effective in debris removal including the use of OPW as irrigant following instrumentation with 5% NaOCl. Neither syringe nor ultrasonic irrigation with OPW following instrumentation with OPW removed smear layer or debris effectively. CONCLUSIONS: The most effective irrigation technique for smear removal was 15% EDTA irrigation by means of syringe following instrumentation with 5% NaOCl solution. However, the most effective irrigation technique for debris removal was ultrasonic irrigation regardless of irrigant used. OPW irrigation by means of syringe following instrumentation with 5% NaOCl showed a similar effect to that of 15% EDTA irrigation for removal of smear layer and debris.     

The evaluation of removal of calcium hydroxide paste from an artificial standardized groove in the apical root canal using different irrigation methodologies

AIM: To evaluate the capacity to remove a calcium hydroxide (Ca(OH)2) paste from the root canal and to evaluate the efficacy of Ca(OH)2 removal during passive ultrasonic irrigation using either sodium hypochlorite (NaOCl) or water as an irrigant. METHODOLOGY: Sixteen mandibular premolars were used. Each root was prepared to the apical foramen using GT instruments of size 30, 0.06 taper. Each root was split longitudinally. In one half of the root, a groove was cut in the canal wall 2-6 mm from the apex which was then filled with a Ca(OH)2 paste. Subsequently the roots were reassembled. In group 1 (n = 16), the teeth were ultrasonically irrigated using 50 mL 2.0% NaOCl as the irrigant. Group 2 (n = 16) was treated in the same manner as group 1, but using 50 mL water in place of the NaOCl. In group 3 (n = 16), the teeth were irrigated by syringe injection of 50 mL 2.0% NaOCl. The quantity of remaining Ca(OH)2 in the groove was scored and the data analysed with Kruskal-Wallis and Mann-Whitney tests. RESULTS: The difference in remaining Ca(OH)2 between all groups was statistically significant (P < 0.001). Group 1 had significantly lower scores than group 2 (P < 0.001) and group 3 (P = 0.002), but there was no significant difference between groups 2 and 3 (P = 0.765). CONCLUSIONS: Passive ultrasonic irrigation with 2% NaOCl was more effective in removing Ca(OH)2 paste from artificial root canal grooves than syringe delivery of 2% NaOCl or water as irrigant.     

Assessment of smear layer removal protocols in curved root canals

This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty‐four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1 mL of 17% ethylenediaminetetraacetic acid (EDTA) ), 5EDTA (syringe irrigation with 5 mL of 17% EDTA), 1EDTA‐P (syringe irrigation with 1 mL of 17% EDTA + pumping with gutta‐percha point), 5EDTA‐P (syringe irrigation with 5 mL of 17% EDTA + pumping with gutta‐percha point), 1EDTA‐EA (syringe irrigation with 1 mL of 17% EDTA + EndoActivator) and 5EDTA‐EA (syringe irrigation with 5 mL of 17% EDTA + EndoActivator). Final rinsing was carried out over 3 min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA‐EA group and the other groups (Kruskal–Wallis and Dunn's post‐hoc tests, P < 0.05). The combination of 5 mL of 17% EDTA and 3 mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used.     

Effect of Different Irrigation on Smear Layer Removal after Post Space Preparation

The purpose of this study was to evaluate the effect of different irrigating solutions on smear layer removal and dentinal tubule opening on root canal surfaces after post space preparation and to study whether additional ultrasonic irrigation has any effect on smear layer removal. Forty-eight anterior teeth were treated endodontically. After post space preparation, they were assigned to six groups: group 1, EDTA; group 2, EDTA with ultrasonic activation; group 3, sodium hypochlorite (NaOCl); group 4, NaOCl with ultrasonic activation; group 5, sodium chloride (NaCl); and group 6, NaCl with ultrasonic activation. Specimens were examined under a field-emission scanning electron microscope and scored for debris removal and dentinal tubule opening at the coronal, middle, and apical thirds of the root canal. The results showed that EDTA performed significantly better than NaCl and NaOCl in smear layer removal and dentinal tubule opening. Additional ultrasonic irrigation did not improve smear layer removal significantly.     

Effect of Different Final Irrigation Methods on the Removal of Calcium Hydroxide from an Artificial Standardized Groove in the Apical Third of Root Canals

Introduction

The aim of this study was to compare the efficacy of conventional syringe, ultrasonic, EndoVac (Discus Dental, Culver City, CA), and Self-Adjusting File (SAF) (Re-Dent-Nova, Ra'nana, Israel) irrigation systems in removing calcium hydroxide (Ca[OH]₂) from simulated root canal irregularities.

Methods

The root canals of 88 extracted single-rooted teeth were prepared using ProTaper rotary instruments (Dentsply Maillefer, Ballagiues, Switzerland) up to size F4. The roots were split longitudinally, and a standardized groove was prepared in the apical part of 1 segment. The root halves were reassembled, and Ca(OH)₂ medicament was placed into the root canals using a Lentulo spiral. The roots were randomly divided into 4 experimental groups and 2 control groups according to the different irrigation systems used: conventional syringe irrigation, continuous passive ultrasonic irrigation (PUI), EndoVac irrigation, and SAF irrigation. Each group was then divided into 2 subgroups (n = 10) according to the irrigation protocol: subgroup 1: 10 mL 2.5% NaOCl and subgroup 2: 10 mL 17% EDTA + 10 mL 2.5% NaOCl. The amount of remaining medicament was evaluated under a stereomicroscope at 30× magnification using a 4-grade scoring system. The influences of the different Ca(OH)₂ medicament removal methods and irrigation protocols were statistically evaluated using 2-way analysis of variance and Tukey post hoc tests.

Results

In the NaOCl-irrigated groups, PUI removed significantly more Ca(OH)₂ medicament than the other techniques (P < .05). There was no significant difference among the other groups (P > .05). In the EDTA/NaOCl-irrigated groups, the SAF and PUI removed significantly more Ca(OH)₂ than the other techniques (P < .05).

Conclusions

The use of the SAF system with the combination of EDTA and NaOCl enhanced Ca(OH)₂ removal when compared with the use of only NaOCl irrigation with the SAF. Continuous PUI and SAF were more effective than EndoVac, and conventional syringe irrigation in the removal of the Ca(OH)₂ medicament from an artificial standardized groove in the apical part of the root canal.     

下颌第一磨牙管间峡区清理技术的体外研究

目的探讨通过组织学方法观察和评价次氯酸钠与超声技术和（或）氢氧化钙联合应用对根管及管间峡区内有机碎屑的清理效果．为管间峡区清理技术的建立提供实验依据。方法收集新鲜拔除的下颌第一磨牙45颗，用ProTaper手用锉预备近颊和近舌两根管后，将45例近中根随机分为A、B和C三组．分别采用以下方法完成根管清理：A组5．25％NaOCl超声冲洗1min，B组和C组均先用Ca（OH）2糊剂处理根管24h．再分别通过超声冲洗和常规冲洗技术清理根管．冲洗液均为0．5％NaOCl.标本脱钙包埋后．取距根尖1、1．5、2、2．5、3mm处的切片各1张作为观察片，行HE染色。用图像软件分析根管及管间峡区内有机碎屑的含量．计算根管和管间峡区清洁度并对数据进行统计学分析。结果A组和B组的根管清洁度（根尖1～2．5mm水平）和管间峡区清洁度（根尖1～3mm水平）均优于C组（P〈0．05），A、B组间的差异不具有统计学意义。结论Ca（OH）2糊剂和0．5％NaOCl超声冲洗联合应用可获得较理想的根管及管间峡区清理效果．可替代5．25％NaOCl超声冲洗法成为一种安全、有效的根管及管间峡区清理技术。     

A novel model for testing the efficiency of removal of calcium hydroxide from complex root canal anatomies

The purpose of this study was to evaluate the efficacy of several irrigation protocols in the removal of calcium hydroxide [Ca(OH)₂] from simulated internal root resorption cavities in a complex root canal anatomy model. The 20° to 35° curved mesiobuccal roots of 94 maxillary molars were sectioned longitudinally; internal resorption cavities were prepared in the apical third of the canal walls. Calcium hydroxide was placed into the cavities and the root halves reassembled. Four teeth were used as controls, and 90 teeth were randomly divided into six experimental groups (n = 15), according to the irrigation protocols used: syringe irrigation; H₂O₂ (HP); Navitip FX; Vibringe‐syringe; Vibringe‐NaviTip FX; ultrasonically activated irrigation (UAI) using an ultrasonic K‐file. In the HP group, 2.5% NaOCl and 3% H₂O₂ were used, while 2.5% NaOCl and 17% EDTA were used in the remaining groups. Stereomicroscope images and radiographs were used to measure the remaining Ca(OH)₂. The model proved to be suitable for simulating complex anatomy. Positive correlation was found between stereomicroscope and radiographic analyses (P < 0.05). UAI removed significantly more Ca(OH)₂ than the other experimental groups (P < 0.05). The HP group was the least efficient protocol (P < 0.05). It would appear that a reliable model has been developed that simulates complex root canal anatomy. Irrigant activation protocols enhanced Ca(OH)₂ removal.     

The influence of volume, type of irrigant and flushing method on removing artificially placed dentine debris from the apical root canal during passive ultrasonic irrigation

AIM: To determine the influence of volume, irrigant and method of flushing on the removal of artificially-placed dentine debris from the apical part of root canals during passive ultrasonic irrigation. METHODOLOGY: Access cavities were prepared in 15 canine teeth and their root canals instrumented to size 20, 0.10 taper. Each root was split longitudinally, forming two halves. A groove was cut in the canal wall 2-6 mm from the apex in each half which was then filled with dentine debris prior to the roots being reassembled. All canals were ultrasonically irrigated, using a size 15, 0.02 taper smooth wire to a length of 21 mm that was placed in the canal to the apical foramen. In group 1 the canal was flushed with a continuous flow of 50 mL 2% sodium hypochlorite (NaOCl). In group 2 the continuous flow was not used but the canal was flushed with 12 mL 2% NaOCl, at a rate of 2 mL 30 s-1 using a syringe. Group 3 was treated in the same way as group 2 but the canal was flushed with 6 mL 2% NaOCl, at a rate of 2 mL min-1. Group 4 was treated in the same way as group 1 but water was used as the irrigant. Before and after irrigation, images of the grooves were captured and stored. The quantity of dentine debris in the groove was evaluated. The differences in debris scores between the experimental groups were analysed with the Kruskal-Wallis test and the Mann-Whitney U-test. The level of significance was set at P=0.05. RESULTS: The difference between all groups was statistically significant (K-W test P<0.001).Groups 1, 2 and 3 differed significantly from group 4 (P<0.001); there was no significant difference between groups 1, 2 and 3 (P=0.550). CONCLUSIONS: Syringe delivery of 2% NaOCl (6 and 12 mL) was as effective as a continuous flow of 2% NaOCl (50 mL). Water was not effective in removing dentine debris from grooves in the apical portion of root canals.     

Smear Layer Removal Using Passive Ultrasonic Irrigation and Different Concentrations of Sodium Hypochlorite

IntroductionThe present study evaluated the effect of passive ultrasonic activation (PUI) of EDTA solution followed by conventional irrigation with 2 concentrations of sodium hypochlorite (NaOCl) on smear layer removal.MethodsFifty single-root mandibular premolars were chemomechanically prepared with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments and 1% NaOCl. The roots were cleaved, and the dentin surfaces were analyzed with scanning electron microscopy operated at a low vacuum. Images were obtained from previously demarcated areas in each root canal third. The teeth were reassembled and distributed into 5 groups according to the final irrigation protocols (n = 10): group 1, EDTA/PUI + 1% NaOCl; group 2, EDTA/PUI + 5% NaOCl; group 3, EDTA/CI + 1% NaOCl; group 4, EDTA/CI + 5% NaOCl; and group 5 (negative control), saline solution/PUI. After irrigation, the teeth were reseparated and prepared for conventional high-vacuum scanning electron microscopy of the same dentin surface that was previously analyzed. The amount of debris was classified using a 4-point scoring system. Data were analyzed with Kruskal-Wallis and Dunn tests at α = 0.05.ResultsGroups 1 and 2, which used PUI and different concentrations of NaOCl, were not significantly different; however, they differed significantly from group 3 (P < .05). With respect to canal cleanliness at different root thirds, all groups showed the worst cleaning at the apical third.ConclusionsPUI activation of the EDTA irrigant is required when canal debridement is performed with EDTA and a lower concentration of NaOCl.