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.     

Does endodontic post space irrigation affect smear layer removal and bonding effectiveness?

The effect of different post space irrigants on smear layer removal and dentin bond strength was evaluated. Sixty-six extracted sound maxillary central incisors were endodontically treated. After post space preparation, the teeth were assigned to three groups of 22 teeth each. The teeth of these three groups were irrigated for 1 min with 17% ethylenediaminetetracetic acid (EDTA) (group 1), 5.25% sodium hypochlorite (NaOCl) (group 2), or 0.9% sodium chloride (NaCl) (group 3). In each group, eight specimens were split longitudinally for smear layer evaluation, and the other fourteen specimens were filled with a self-etching adhesive system (Panavia F). Four of 14 specimens of each group were prepared for evaluation of the resin–dentin interdiffusion zone (RDIZ) and resin tags, and the other 10 specimens were serially sectioned for push-out test analysis. Smear layer removal and bond strength were affected by different post space irrigants. EDTA removed the smear layer extremely effectively and, as a result, improved the bond strength at each region (apical, middle, and coronal) of the roots. Resin tag formation and the RDIZ were also affected by different irrigants and in accordance with bond strength. Therefore, removal of the smear layer use a self-etching luting system plays an important role in bonding effectiveness.     

Effects of rotary instruments and ultrasonic irrigation on debris and smear layer scores: a scanning electron microscopic study

AIM: This study evaluated debris and smear layer scores after two types of instruments manufactured from different alloys were used to ultrasonically activate irrigants during canal preparation. The influence of two rotary preparation techniques on cleanliness of the shaped canals was also studied. METHODOLOGY: Apical stops were prepared to size 45 in 42 single-canalled extracted premolars and canines, which were divided into six equal groups. Groups 1, 2 and 3 were prepared by ProFile.04 (PF) while groups 4, 5 and 6 were prepared by Lightspeed (LS). All groups were irrigated using 5.25% NaOCl and 17% EDTA. Irrigants in groups 2 and 5 were ultrasonically activated using a size 15 steel K-file and by a blunt flexible nickel-titanium wire in groups 3 and 6. Groups 1 and 4 served as negative controls. Roots were split and canal walls examined at 15x, 200x and 400x magnification in an SEM. Smear layer and debris scores were recorded at 3, 6 and 9 mm levels using a 5-step scoring scale and a 200- micro m grid. Means were tested for significance using nonparametric Mann-Whitney U and Kruskal-Wallis tests. RESULTS: Debris and smear layer scores for the six groups varied from 1.98 +/- 1.04 to 3.47 +/- 0.97 and from 1.37 +/- 0.4 to 2.36 +/- 0.99, respectively. Although all groups had significantly higher smear layer and debris scores at the 3 mm levels compared to the 9 mm levels (P < 0.05), no significant differences were recorded due to the ultrasonic energy transmitted by the two alloys. CONCLUSION: Ultrasonically activated irrigants did not reduce debris or smear layer scores. This finding was not influenced by the material nor by the design of the instrument used to transmit ultrasonic activation.     

Effect of F-File on removal of the smear layer: a scanning electron microscope study

The aim of this study was to evaluate the effectiveness of F-File with NaOCl on removal of the smear layer. A total of 48 single-rooted teeth were instrumented using crown-down technique with one of the irrigation agents: distilled water, 5.25% NaOCl, RC-Prep, Glyde, MTAD or F-File with NaOCl. The remaining smear layer was scored at cervical, middle and apical thirds of the roots with SEM. In all the canals of experimental groups the coronal sections were cleaner than the middle and apical sections except with distilled water (P<0.001). In the coronal third, intensive smear layer was observed in distilled water, NaOCl and F-File groups and less smear layer in MTAD (P<0.05) and least in RC-Prep and Glyde groups. In the middle third, RC-Prep and Glyde groups had less smear layer than the other groups (P<0.001). In the apical third, there was intensive smear layer in all specimens and statistical analyses showed no significant difference among the groups (P>0.05). The F-file failed to improve the effect of NaOCl in removing smear layer.     

Effect of 17% EDTA and MTAD on intracanal smear layer removal: A scanning electron microscopic study

The purpose of this study was to determine the effectiveness of MTAD as the final irrigant to remove the smear layer, compared with that of 17% EDTA, both following root canal irrigation with 5.25% sodium hypochlorite (NaOCl). Fifty‐five extracted maxillary and mandibular single‐rooted human teeth were prepared by a crown‐down technique using rotary 0.04 and 0.06 taper nickel‐titanium files. 5.25% sodium hypochlorite was used as the intracanal irrigant. The canals were then treated with 5 mL of one of the following solutions as final rinse: 5.25% sodium hypochlorite, 17% EDTA or MTAD. The presence or absence of smear layer in the coronal, middle and apical portion of each canal was examined with a scanning electron microscope. The results showed that MTAD is an effective final rinse solution for removing the smear layer in canals irrigated with sodium hypochlorite. When 17% EDTA was used as a final rinse, the smear layer was removed from the middle and coronal thirds of canal preparations, but it was less effective in the apical third of the canals.     

Effects of irrigation on debris and smear layer on canal walls prepared by two rotary techniques: a scanning electron microscopic study

Debris and smear layer were evaluated in canals prepared with either Lightspeed (LS) or ProFile (PF) rotary instruments. Irrigants used were tap water (group A) or alternating 5.25% NaOCl and 17% EDTA (group B). Apical stops were prepared to size 52.5 in the LS and to size 6 (approximately ISO size 36) in the PF techniques. The roots were split longitudinally and examined at apical, middle and coronal levels for debris and the smear layer using a 5-step scale. Using only water, mean debris scores were similar for LS and PF. In contrast, with EDTA/NaOCl, LS- and PF-prepared canals had similar debris scores at the apical and coronal levels, but there was a significant difference at the middle level. Mean smear layer scores were similar in LS- and PF-shaped canals when water was the sole irrigant. In contrast, with NaOCl and EDTA, mean smear layer scores were significantly different at the apical and middle levels, but not at the coronal level. Neither technique was superior in removing debris, but larger canal preparations obtained in this study with LS instruments enabled a more effective removal of the smear layer in the EDTA-NaOCl group.     

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。     

Light and scanning electron microscopic evaluation of Glyde File Prep in smear layer removal

AIM: To evaluate the effectiveness of Glyde File Prep used in conjunction with sodium hypochlorite irrigation in the removal of smear layer produced during root canal instrumentation. METHODOLOGY: Thirty-nine extracted human teeth with single root canals were used. Access cavities were prepared and the teeth divided into three groups of 13 teeth each. Each group was treated by one of the three different regimes of irrigation and conditioning during root canal instrumentation. Group A: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 1% NaOCl; group B: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 17% EDTA; group C: Glyde File Prep coated on each instrumentation file used in conjunction with 0.5 mL 1% NaOCl irrigation after each file size and an additional final irrigation of 10 mL 1% NaOCl. The teeth were then longitudinally grooved and sectioned. Root canal cleanliness was evaluated with the aid of a Nikon light microscope (x40 and x100) and scanning electron microscope (x1000 and x3000). The debris scores obtained at three canal regions were compared statistically within the same group and among different groups using repeated measurements of analysis of variance (anova) with Bonferroni adjustments and anova with posthoc Tukey HSD, respectively. RESULTS: The canals treated with EDTA and Glyde File Prep were significantly cleaner than those treated with NaOCl alone. The apical region of the root canals generally displayed more residual smear layer, but the difference was not significant. CONCLUSIONS: Used in conjunction with NaOCl irrigation, Glyde File Prep was effective in removing smear layer produced during root canal instrumentation.     

Efficacy of three different irrigation techniques in the removal of smear layer and organic debris from root canal wall: a scanning electron microscope study

AimAim of this study was to compare the removal of smear layer and organic debris within the tooth canal among conventional needle irrigation, EndoVac and Endoactivator.MethodologyEighty single-rooted extracted human teeth were prepared with rotary NiTi instrumentation and randomly separated into 4 groups. Twenty teeth were used as positive control (Group 1), irrigated with only saline. Teeth assigned to Group 2 (n = 20) received irrigation with a conventional syringe and a 30-gauge needle (NaviTip, Ultradent, South Jordan, UT); samples in Group 3 (n = 20) were rinsed with an irrigation device based on apical negative pressure (EndoVac, Discus Dental, Culver City, CA) and teeth in Group 4 (n = 20) were treated with a sonic irrigation system (EndoActivator, Dentsply Tulsa Dental, Tulsa, OK, USA). The amount of residual smear layer and debris was evaluated under a scanning electron microscope, and a semi-quantitative score was assigned to each root at the coronal, middle and apical thirds; the chi-square test was used to compare the results of the S.E.M. analysis.ResultsEndoActivator performed the best cleansing for both smear layer and organic debris in all root canal thirds, followed by EndoVac and conventional irrigation (p > 0.001). EndoVac and conventional irrigation showed better cleaning in the coronal area, whereas EndoActivator performed an homogeneous cleansing at all levels.ConclusionsThe EndoVac system and the EndoActivator system demonstrated significantly more efficacy in cleansing root canal walls than conventional needle irrigation.     

Tannic acid for smear layer removal: pilot study with scanning electron microscope

The effects of a 25% tannic acid solution applied to the surface of prepared dentin was compared with untreated prepared dentin surfaces. The following results were demonstrated by electron microscope observation: (1) cavity preparations created an amorphous dentinal smear layer, (2) placement of a 25% tannic acid solution for 15 seconds removed the smear layer, (3) the contents of the dentinal tubules were not removed and no enlargement of dentinal tubules was found, and (3) a clean dentinal surface was observed.     

Efficacy of different final irrigation activation techniques on smear layer removal

Introduction

Different techniques and irrigant delivery devices have been proposed to increase the flow and distribution of irrigating solutions within the root canal system. The aim of this study was to compare smear layer removal after final irrigant activation with apical negative pressure (ANP), manual dynamic agitation (MDA), and passive ultrasonic irrigation (PUI).

Methods

Forty single-rooted human mandibular premolars were decoronated to a standardized length of 16 mm. They were cleaned and shaped by using ProTaper system to size F4 and NaOCl 2.5%. The specimens were divided into 4 equal groups (n = 10) according to the final irrigation activation technique: group 1, passive irrigation (PI); group 2, apical negative pressure (ANP) (EndoVac); group 3, manual dynamic activation (MDA); and group 4, passive ultrasonic irrigation (PUI). Samples were split longitudinally and examined under scanning electron microscope for smear layer presence.

Results

PI and PUI had the highest smear scores, with no significant differences between them. This was followed by MDA and finally ANP, which showed the statistically significant lowest mean score at P ≤ .05.

Conclusions

Final irrigant activation with ANP and MDA resulted in better removal of the smear layer than with PUI or PI.     

Effectiveness of different endodontic files for preparing curved root canals: a scanning electron microscopic study

Abstract In this study, the effect of using four endodontic files from different manufacturers on the final shape of 80 prepared curved root canals of extracted single-rooted teeth were comparatively analyzed with scanning electron microscopy. The instruments tested were Tri-files, Flex-R files, Flexofiles and conventional K-type files. All files were used with in and out linear movements with a circumferential motion starting with a size 15 file. Final preparation of the apical thirds was performed with a size 30 file. Shaping effectiveness of the tested files was qualitatively evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging, specially in the apical third of the root canals. A well-centered and tapered preparation without apical transportation or ledging was detected when Tri-file or Flex-R files were used. Conversely, the use of Flexofile or conventional K-type files resulted in frequent alteration of the initial pattern of the root canals, showing an hourglass preparation with alteration of the apical constriction and ledge formations.     

Evaluation of canal cleanliness and smear layer removal after the use of the Quantec-E irrigation system and syringe: a comparative scanning electron microscope study

OBJECTIVE: The purpose of this study was to evaluate canal cleanliness and smear layer removal after use of the Quantec-E irrigation system and to compare the system with traditional irrigation. STUDY DESIGN: Forty anterior teeth were randomly assigned to 4 groups. Group A consisted of 15 teeth that were instrumented with .12, .10, .08, .06 and .04 tapered rotaries while simultaneously irrigated via the Quantec-E irrigation pump with 12 mL of 5.25% NaOCl, followed by 6 mL EDTA 17% in crown-down fashion, with a final flush with 4 mL 5.25% NaOCl. Group B consisted of 15 teeth that were instrumented with the same instrument sequence, and irrigated with the same volumes via traditional needle and syringe. Group C consisted of 5 teeth that were sectioned and examined under a scanning electron microscope (SEM) without any instrumentation and served as a negative control. Group D consisted of 5 teeth that were instrumented dry, without any irrigation, and served as a positive control. All teeth were sectioned buccolingually and examined with SEM at 700x magnification in the apical, middle, and coronal portions of the canals. Analysis of SEM images was performed by 5 independent examiners using a 4-point scoring system. RESULTS: Irrigation with the Quantec-E irrigation pump resulted in cleaner canal walls, less debris, and more complete removal of the smear layer within the coronal one third, when compared with syringe irrigation. However, no difference was observed in the middle and apical one thirds of the root canal. CONCLUSION: There was no significant difference between the 2 irrigation systems.     

The effect of different irrigation protocols on smear layer removal in root canals of primary teeth: a SEM study

Objective: The purpose of this study was to compare the efficacy of different irrigation protocols on smear layer removal in root canals of primary teeth by scanning electron microscopy (SEM).

Material and methods: The study was conducted with 40 extracted maxillary primary incisor teeth divided into four groups (n?=?10) as 1% sodium hypochlorite (NaOCl), 10% ethylenediaminetetraacetic acid (EDTA)+1% NaOCl, 6% citric acid (CA)+1% NaOCl, and 0.9% physiological saline (PS). After the irrigation procedures, root canal walls were examined by SEM and the efficacies of irrigation solutions in smear layer removal were scored and compared. Data were analyzed using Kruskal–Wallis, Friedman and Siegel Castellan tests.

Results: The smear layer removal was found to be statistically more effective in groups of 10% EDTA + 1% NaOCl and 6% CA + 1% NaOCl when compared with the other groups (p?<?.05). Smear removal efficacy was statistically significantly higher in coronal and medium thirds when compared with the apical regions in the experimental groups.

Conclusions: It was concluded that 10% EDTA + 1% NaOCl and 6% CA + 1% NaOCl could be alternative irrigation protocols regarding smear layer removal. However, due to the absence of erosive dentinal changes, it might be suggested that using 6% CA + 1% NaOCl can be recommended compared to 10% EDTA + 1% NaOCl in primary root canals.     

Effect of manual dynamic activation on smear layer removal efficacy of ethylenediaminetetraacetic acid and SmearClear: An in vitro scanning electron microscopic study

The purpose of the present study was to evaluate the effect of manual dynamic activation (MDA) with a master gutta‐percha point on the smear layer removal efficacy of 17% ethylenediaminetetraacetic acid (EDTA) and SmearClear. Fifty freshly extracted human single‐rooted teeth were prepared using ProTaper rotary system up to F3 size. The prepared teeth were divided into five groups on the basis of final irrigation received. Group A: 3% NaOCl solution (negative control group). Group B: 5 mL of 17% EDTA. Group C: 1 mL of 17% EDTA + MDA for 2 min + 4 mL of 17% EDTA rinse. Group D: 5 mL of SmearClear. Group E: 1 mL of SmearClear + MDA for 2 min + 4 mL of SmearClear rinse. Prepared samples were decoronated and then longitudinally split into two halves and evaluated under scanning electron microscope. Representative images at coronal, middle and apical third level were taken and scored for the amount of smear layer present, using a three‐score system. The data were analysed through Kruskal–Wallis and Mann–Whitney U‐test. The root canal surfaces of samples of group C and group E (where MDA was done) were significantly cleaner in apical third regions than those of group B and group D (P < 0.05).     

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.