Efficacy of several concentrations of sodium hypochlorite for root canal irrigation.

Sodium hypochlorite (NaOCl) has been recommended for irrigation during root canal preparation. This investigation used scanning electron microscopy to examine instrumented and uninstrumented surfaces in the middle third of root canals following the use of several concentrations of NaOCl (5.25%, 2.5%, 1.0%, and 0.5%). NaOCl was delivered with either an endodontic irrigation needle or an ultrasonic device. All of the concentrations of NaOCl with either delivery system were very effective in flushing out loose debris from the root canals. A smear layer with some exposed dentinal tubules was seen on all instrumented surfaces regardless of concentration of NaOCl or irrigation device. NaOCl in concentrations of 5.25%, 2.5%, and 1% completely removed pulpal remnants and predentin from the uninstrumented surfaces. Although 0.5% NaOCl removed the majority of pulpal remnants and predentin from the uninstrumented surfaces, it left some fibrils on the surface.     

Effect of calcium hydroxide and four irrigation regimens on instrumented and uninstrumented canal wall topography

The topography of instrumented and uninstrumented canal walls exposed to calcium hydroxide and four different irrigation regimens was observed by scanning electron microscopy. After chemomechanical debridement, one tooth in each matched pair was medicated with calcium hydroxide. One week later, the teeth were irrigated and split longitudinally for evaluation. When no calcium hydroxide was used, predentin and pulpal debris covered the dentinal tubules of the uninstrumented surfaces in specimens irrigated with water or EDTA, but was absent on uninstrumented surfaces in specimens irrigated with NaOCl or NaOCl and EDTA. A typical smear layer was absent in instrumented specimens irrigated with NaOCl and EDTA, but covered the dentinal tubules of the instrumented surfaces of the EDTA irrigated specimens (partially) and the water or NaOCl irrigated specimens (completely). Calcospherites or their remnants were seen on the uninstrumented canal walls of specimens irrigated with NaOCl or NaOCl and EDTA, respectively. Calcium hydroxide use did not alter the surface topography in specimens irrigated with water, EDTA, or NaOCl, but seemed to erode the intertubular dentin in specimens irrigated with NaOCl and EDTA. All irrigants seemed to effectively remove most of the calcium hydroxide.     

Surface debris of canal walls after post space preparation in endodontically treated teeth: a scanning electron microscopic study

PURPOSE: To evaluate surface cleanliness of root canal walls along post space after endodontic treatment using 2 different irrigant regimens, obturation techniques, and post space preparation for adhesive bonding. STUDY DESIGN: Forty teeth, divided into 4 groups, were instrumented, using Ni-Ti rotary files, irrigated with NaOCl or NaOCl+EDTA and obturated with cold lateral condensation (CLC) or warm vertical condensation (WVC) of gutta-percha. After post space preparation, etching, and washing procedure, canal walls were observed using a scanning electron microscope (SEM). Amount of debris, smear layer, sealer/gutta-percha remnants, and visibility of open tubules were rated. RESULTS: Higher amounts of rough debris, large sealer/gutta-percha remnants, thick smear layer, and no visibility of tubule orifices were recorded in all the groups at apical level of post space. At middle and coronal levels areas of clean dentin, alternating with areas covered by thin smear layer, smaller debris, gutta-percha remnants, and orifices of tubules partially or totally occluded by plugs were frequently observed. CONCLUSIONS: After endodontic treatment, obturation, and post space preparation SEM analysis of canal walls along post space shows large areas (covered by smear layer, debris, and sealer/gutta-percha remnants) not available for adhesive bonding and resin cementation of fiber posts.     

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。     

二氧化氯作为根管超声冲洗剂的清洁效果

目的 评价二氧化氯用作根管超声冲洗剂的清洁效果.方法 选择30颗离体单根管前磨牙,截去牙冠后随机平分成A、B、C三组,用手持不锈钢器械逐步后退法进行根管预备,超声波冲洗,冲洗剂分别为蒸馏水、1.0%次氯酸钠和0.1%二氧化氯溶液.完成根管预备后纵行劈开牙根,扫描电镜观察,在根管颈1/3、中1/3、尖1/3各部位随机拍照,在电镜照片上评定根管壁上碎屑和玷污层记分,计数牙本质小管开放数目,并进行统计学分析.结果 A、B、C各组碎屑记分差异无统计学意义(P＞0.05);B、C两组的玷污层明显少于A组,差异有统计学意义(P＜0.01);牙本质小管开放数也明显多于A组,差异有统计学意义(P＜0.01),但B、C两组之间差异无统计学意义(P＞0.05).结论 0.1%二氧化氯溶液用作根管超声冲洗剂,具有良好的清洁作用,对碎屑和玷污层的去除能力不亚于1.0%次氯酸钠,明显优于蒸馏水.     

Evaluation of penetration and adaptation of three different sealers: a SEM study

In this study, dentinal penetration and adaptation of three endodontic sealers were evaluated by using scanning electron microscope (SEM). Seventeen recently extracted, human maxillary anterior teeth were used. After the crowns were removed from the cementoenamel junction, the root canals were instrumented. The teeth were then randomly divided into three groups of five roots each and two teeth were used as controls. The smear layer was removed with EDTA and NaOCl. The canals were obturated with AH 26, CRCS, RSA sealers and gutta-percha using lateral condensation technique. Each root was sectioned longitudinally and then prepared for SEM evaluation. The SEM results showed that AH 26 was the best sealer penetrating into dentinal tubules and adapted to dentinal walls when compared with the CRCS and RSA. The CRCS and RSA occluded the orificies of dentinal tubules. The RSA showed that the penetration was less than AH 26 and more than CRCS.     

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 effect of application time of EDTA and NaOCl on intracanal smear layer removal: an SEM analysis

AIM: To verify, under the scanning electron microscope (SEM), the influence of irrigation time with ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) on intracanal smear layer removal. METHODOLOGY: Twenty-one extracted human permanent teeth with single straight root canals were included. The root canals of the teeth were instrumented and, at the end of preparation, were irrigated with 3 mL of 15% EDTA, followed by 3 mL of 1% NaOCl for 1 min (group 1), for 3 min (group 2), and for 5 min (group 3). The canals of teeth in group 4 (control) did not receive the final irrigation. The teeth were sectioned longitudinally and prepared for an SEM. The dentinal wall of cervical, middle and apical thirds was graded according to the amount of debris and smear layer remaining on the walls. The results were analysed using the Kruskal-Wallis and Conover-Inman tests. RESULTS: In all the canals of experimental groups irrigation with EDTA and NaOCl completely removed the smear layer from the cervical and middle thirds. In the apical third, the dentine surface were partially covered, particularly in the teeth of group 1, where there was significantly more smear layer when compared with the other thirds in the same group (P<0.007). However, the Kruskal-Wallis test showed overall that there were no significant differences between groups 1, 2 and 3 (P>0.05). CONCLUSION: In this limited laboratory study, canal irrigation with EDTA and NaOCl for 1, 3 and 5 min were equally effective in removing the smear layer from the canal walls of straight roots.     

Lactic acid root canal irrigation for dowel and core treatment: a pilot study

STATEMENT OF PROBLEM: Various solutions used to irrigate root canals and remove the smear layer prior to obturation of a root canal affect surface topography and may influence the sealing ability of endodontic therapy, retention of endodontic dowels, and restoration survival. PURPOSE: This study microscopically evaluated the effects of varying dilutions of lactic acid on the removal of the smear layer created by hand instrumentation in the coronal, middle, and apical thirds of root canals. Lactic acid solution was compared with other solutions deemed to be suitable root canal irrigants. MATERIAL AND METHODS: Thirty-five extracted human single-rooted teeth were manually shaped with files (K-flex) using the step-back technique. ISO size 50 files were used as master apical files. The teeth were equally divided into 7 test groups according to the canal irrigant used. While the teeth were cleaned and shaped, the root canals were irrigated with 3 mL of 1 of the following irrigants between each file size and as a final flush: no irrigant (control), 5% hydrogen peroxide, 5% sodium hypochlorite, a combination of 5% hydrogen peroxide and 5% sodium hypochlorite, 15% ethylenediaminotetraacetic acid (EDTA), 10% lactic acid, or 20% lactic acid. Specimens were critical-point dried and freeze-fractured for scanning electron microscope analysis at 3 sites (cervical, middle, and apical). RESULTS: Scanning electron micrographs showed no differences between the cervical, middle, and apical levels of the specimens tested with any of the irrigants used. Also, no difference was found within individual groups. The surface of the control specimens had a smear layer that contained smear plug material. Hydrogen peroxide and sodium hypochlorite used separately and in combination consistently produced surfaces with a smear layer. Lactic acid solutions and EDTA, however, removed the dentinal smear layer but left remnants of smear plugs in the dentinal tubules. CONCLUSIONS: Within the limitations of this study, differences related to the type of irrigant used were found in the characteristics of the pulpal dentin surface. Although lactic acid effectively cleaned and smoothed the dentin walls of root canals of endodontically prepared teeth, further study is needed before this procedure can be recommended for routine clinical use.     

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.     

Evaluation of the smear layer removal effectiveness of EDTA using two techniques: an SEM study

Obtaining the cleanest canal possible before obturation is one of the goals of endodontic treatment. The purpose of this study was to compare the smear layer removal capability of ethylenediamine tetra-acetic acid (EDTA) application with passive ultrasonic and cotton wrapped on reamer activation. Twelve extracted human teeth with single root canals were used for the study. They were conventionally hand instrumented using reamers and K files. The apical aspect of the canals was enlarged to a #40 file. The teeth were divided into 4 four groups, instrumented and irrigated as follows: Group-A EDTA agitated at the end of preparation with cotton wrapped on a reamer for 1 min; Group-B EDTA applied with ultrasonic agitation for 1 min; Group-C irrigated with EDTA+sodium hypochlorite (NaOCl) (negative control group); and Group-D irrigated with distilled water (positive control group). After scanning electron microscopic study at three different levels, smear layer and dentinal tubules were scored. Means were tested for significance using the Z test. When the techniques were compared, the cotton wrapped on reamer agitation method was as successful as the ultrasonic activation of the files. Although all groups had significantly higher smear layer scores at apical compared to coronal sections, no significant differences were recorded.     

17% EDTA与脉冲Nd：YAG激光去除根管壁玷污层疗效的电镜研究

目的对17%EDTA与脉冲Nd：YAG激光对根管壁玷污层清除效果进行分析与比较。方法选取30颗新鲜单根成人离体牙,根管机械预备后随机分为三组,每组10例,分别给予5.25%NaClO冲洗（对照组）、17%EDTA＋5.25%NaClO冲洗以及5.25%NaClO冲洗＋Nd：YAG激光照射处理后,电镜下观察根管侧壁玷污层去除情况。利用计算机图像分析软件计算开放牙本质小管口面积/牙本质面积比。统计学方法采用单因素方差分析,α=0.05。结果EDTA冲洗及Nd：YAG激光照射后均可使根管侧壁玷污层明显减少,但EDTA冲洗对牙本质小管口开放作用明显优于Nd：YAG激光照射组及对照组（P〈0.01）。结论17%EDTA对根管壁玷污层的清除效果优于脉冲Nd：YAG激光,适合于临床广泛应用。     

The smear layer: a phenomenon in root canal therapy

When the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the prescence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and if delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. When it is not removed, the durability of the apical and coronal seal should be evaluated over a long period. If smear layer is to be removed, EDTA and NaOCI solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics, that have been tested. Once this layer is removed, it should be borne in mind that there is a risk of reinfecting dentinal tubules if the seal fails. Further studies are needed to establish the clinical importance of the absence or presence of smear layer.     

Efficacy of chlorhexidine in disinfecting dentinal tubules in vitro

Abstract Solutions of 0.2% and 2% chlorhexidine, 0.2% and 2% sodium hypochlorite (NaOCl) and normal saline were tested for their efficacy in disinfecting dentinal tubules following root canal irrigation in vitro. Freshly extracted bovine incisor roots were prepared as cylindrical shapes, 4 mm high and 5 mm wide with a lumen 2.1 mm wide. After mechanical removal of the cementum and elimination of the smear layer on the dentine surface with EDTA and NaOCl, the root sections were autoclaved and the dentinal tubules infected with E. faecalis (NCTC 775) by incubating in yeast extract glucose broth for 1 week. The root canals were irrigated with 20 ml of an irrigant solution using a syringe. Each irrigant was used in six specimens. Dentine was removed from the canal wall by sterile burs of increasing diameter to give samples 100, 100–300 and 300–500 μm deep. The dentine samples were then cultured to determine the presence and quantity of remaining micro-organisms. The results indicated that chlorhexidine and NaOCl were equally effective antibacterial agents at similar concentrations against the test microorganism. They significantly reduced the bacterial counts in the first 100 μm of dentinal tubules, however up to 50% of dentine samples remained infected following use of both agents.     

A Comparative Study of Smear Layer Removal and Erosion in Apical Intraradicular Dentine With Three Irrigating Solutions: A Scanning Electron Microscopy Evaluation

IntroductionThis study compared the efficacy of BioPure MTAD (Dentsply Tulsa, Tulsa, OK), 17% EDTA, and 42% citric acid in endodontic smear layer removal and degree of erosion in the apical third of endodontic canals.MethodsNinety-six extracted single-rooted human teeth were randomized into four groups (n = 24) and instrumented using System GT nickel-titanium rotary instruments (Dentsply Tulsa, Tulsa, OK). Each canal was irrigated with one of the following solutions: BioPure MTAD, 17% EDTA, 42% citric acid, or 5.25% NaOCl (control). Next, all specimens were irrigated with 5.25% NaOCl.ResultsEvaluation by scanning electron microscopy showed no significant differences among test irrigants in removing the smear layer. However, the efficacy of BioPure MTAD and 17% EDTA in removing the smear layer was significantly greater than 5.25% NaOCl (control). The erosive effects of irrigating solutions could not be evaluated.ConclusionsIn conclusion, the protocols used in this study were not sufficient to completely remove the smear layer in the apical third of prepared root canals.     

The effect of various concentrations of sodium hypochlorite on the ability of MTAD to remove 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 various concentrations of sodium hypochlorite (NaOCl) as an intracanal irrigant before the use of MTAD (a mixture of a tetracycline isomer, an acid, and a detergent) as a final rise to remove the smear layer. Ten operators, using a combination of passive step-back and rotary 0.04 taper, nickel-titanium files, prepared 80 single- and multirooted human teeth. Distilled water, four different concentrations of NaOCl, or MTAD was used as intracanal irrigant. The canals were then treated for 2 min with 5 ml of one of the following solutions as a final rinse: 5.25% NaOCl, sterile distilled water, 17% EDTA, or 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 although MTAD removes most of the smear layer when used as an intracanal irrigant, some remnants of the organic component of the smear layer remain scattered on the surface of the root canal walls. The effectiveness of MTAD to completely remove the smear layer is enhanced when low concentrations of NaOCl are used as an intracanal irrigant before the use of MTAD as a final rinse. This regimen does not seem to significantly change the structure of the dentinal tubules.     

Influence of smear layer on depth of penetration of three endodontic sealers: an SEM study

Abstract— The purpose of this study was to examine the effect of the smear layer on the penetration depth of Sealapex, Roth 811, and CRCS root canal sealers into the dentinal tubules. Forty recently extracted, human single-rooted teeth were used. The crowns were cut and removed at the cemento-enamel junction level and the root canals were prepared to a #60 K-file. The teeth were then randomly divided into two groups of 20, group A and group B. The smear layer was removed from all teeth in group A with EDTA and NaOCl. The smear layer remained in all teeth in group B. Two roots in each group were used as controls. Six roots from each group were obturated with Roth 811 sealer and gutta-percha through lateral condensation. The same process was repeated using sealers CRCS and Sealapex. Each root was then divided in two and prepared for scanning electron microscope observation. The removal of the smear layer allowed penetration of all three sealers into the dentinal tubules to a depth of between 35 μm and 80 μm. Although the CRCS sealer penetrated only up to the 35 mm point, it offered better or complete obturation of the dentinal tubules. The presence of smear layer at the root canal walls obstructed the penetration of all sealers into the dentinal tubules.     

The removal of the smear layer using EGTA: a scanning electron microscopic study

The smear layer associated with endodontic instrumentation is currently thought to be a thin layer that occludes the orifices of the dentinal tubules and covers the intertubular dentin of the prepared canal wall. The purpose of this study was to compare the effect of ethylene glycol bis (beta-amino ethyl ether)-N, N, N', N'-tetra acetic acid (EGTA) and ethylene diamine tetra acetic acid (EDTA) on removal of the smear layer through the scanning electron microscopy. Twenty four single rooted teeth were selected, instrumented and irrigated with various solutions and the specimens were processed for scanning electron microscopy. It was found that though both EGTA and EDTA completely removed the smear layer, EDTA caused erosion and conjugation of the tubules, whereas, EGTA effectively removed the smear layer without inducing any erosion. It was thus concluded that EGTA can be effectively used as an alternative chelator for the removal of the smear layer.     

Cleaning effectiveness of root canal irrigation with electrochemically activated anolyte and catholyte solutions: a pilot study

AIM: The aim of this study was to evaluate the potential of electrochemically activated (ECA) anolyte and catholyte solutions to clean root canals during conventional root canal preparation. METHODOLOGY: Twenty extracted single-rooted human mature permanent teeth were allocated randomly into four groups of five teeth. The pulp chambers were accessed and the canals prepared by hand with conventional stainless steel endodontic instruments using a double-flared technique. One or other of the following irrigants was used during preparation: distilled water, 3% NaOCl, anolyte neutral cathodic (ANC) (300 mg L-1 of active chlorine), and a combination of anolyte neutral cathodic (ANC) (300 mg L-1 of active chlorine) and catholyte. The teeth were split longitudinally and the canal walls examined for debris and smear layer by scanning electron microscopy. SEM photomicrographs were taken separately in the coronal, middle and apical parts of canal at magnification of x800 to evaluate the debridement of extracellular matrix and at a magnification of x2500 to evaluate the presence of smear layer. RESULTS: Irrigation with distilled water did not remove debris in the apical part of canals and left a continuous and firm smear layer overlying compressed low-mineralized predentine. All chemically active irrigants demonstrated improved cleaning potential compared to distilled water. The quality of loose debris elimination was similar for NaOCl and the anolyte ANC solution. The combination of anolyte ANC and catholyte resulted in improved cleaning, particularly in the apical third of canals. The evaluation of smear layer demonstrated that none of the irrigants were effective in its total removal; however, chemically active irrigants affected its surface and thickness. Compared to NaOCl, the ECA solutions left a thinner smear layer with a smoother and more even surface. NaOCl enhanced the opening of tubules predominantly in the coronal and middle thirds of canals, whereas combination of ANC and catholyte resulted in more numerous open dentine tubules throughout the whole length of canals. CONCLUSIONS: Irrigation with electrochemically activated solutions cleaned root canal walls and may be an alternative to NaOCl in conventional root canal treatment. Further investigation of ECA solutions for root canal irrigation is warranted.     

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。