Evaluation of the influence of smear layer on the apical and coronal sealing ability of two sealers

The aim of this in vitro study was to determine the effect of the smear layer on apical and coronal leakage in root canals obturated with AH26 or RoekoSeal sealers. A total of 160 maxillary anterior teeth extracted for periodontal reasons were used. The root canals were prepared to a size #7 with ProFile.06 taper Series 29 rotary instruments in a crown-down manner. Eight groups were created by all possible combinations of three factors: smear layer (present/absent), leakage assessment (apical/coronal), and sealer used (AH26/RoekoSeal). All teeth were obturated using lateral condensation technique of gutta-percha. A fluid filtration method was used to test apical or coronal leakage. According to the results of this study, the smear (+) groups displayed higher apical and coronal leakage than those smear (-) groups for both root canal sealers (p < 0.05). There was no statistically significant difference in either apical or coronal leakage between RoekoSeal and AH26, regardless of the presence or absence of the smear layer (p > 0.05). However, apical leakage was significantly higher than coronal leakage for both root canal sealers used in this study (p < 0.05). Under the conditions of this study, the results indicate that removal of the smear layer has a positive effect in reducing apical and coronal leakage for both AH26 and RoekoSeal root canal sealers.     

The influence of the smear layer on the sealing ability of canal obturation

Summary. The sealing of obturated root canals which had previously been cleaned chemically by EDTA or mechanically by ultrasound was compared using 60 single-rooted teeth in an in vitro study. At first, the canals were manually prepared under copious irrigation with NaOCl. Then the specimens were divided into three experimental groups: in group I (control group) the canals were immediately obturated without further preparation; in group II (ultrasound group) the canals were subjected to ultrasound before being obturated, and in group III (EDTA group) the canals were irrigated with EDTA before being obturated. All speciments were then subjected to dye infiltration before being transversely sectioned at various levels from the apex. The amount of leakage was scored on an arbitrary four-point scale. The results showed some differences in leakage between the three groups at levels close to the apex: EDTA-treated canals showed the least infiltration, while those treated with ultrasound showed significantly less compared with the control group. The role of the smear layer and its removal is discussed in the light of these results.     

An evaluation of sealing ability of calcium hydroxide sealers

Solid core filling material such as gutta-percha has been used to fill the root canal in conjunction with a sealer to prevent apical leakage. The purpose of this study was to compare apical seal of five different root canal sealers. Sixty roots of maxillary central incisors were cleansed and shaped and randomly assigned to one of six groups of ten roots each. The root canals were obturated with gutta-percha and one of the sealers by the lateral-vertical condensation technique. Groups I, II, III, IV, and V consisted of roots in which the canal was filled with gutta-percha along with either Roth's sealer, AH26, Sealapex, CRCS, or Nogenol sealer, respectively. Group VI was filled with gutta-percha and without sealer to serve as a control. The access opening was filled with amalgam. Each tooth was then placed in a capped vial containing 2 X 2 inch gauze pads saturated with distilled water, and the sealer was allowed to set at 37 degrees C in the humidor for 48 hours. The roots, except for the apical 2 mm, were coated with two layers of nail polish. The roots were stained with india ink, decalcified, dehydrated, and then placed in methylsalicylate to make them transparent. The leakage was measured with a filar micrometer eyepiece under a dissecting microscope. The mean apical leakage of six groups was as follows: I = 0.45 mm, II = 0.277 mm, III = 0.343 mm, IV = 0.263 mm, V = 0.336 mm, and VI = 2.310 mm. Results showed no significant difference in the apical seal produced by gutta-percha and the tested root canal sealers.(ABSTRACT TRUNCATED AT 250 WORDS)     

根管螯合冲洗剂去除根管壁玷污层能力的研究

目的 比较各种螯合冲洗剂去除根管壁玷污层的能力，为临床操作提供依据。方法 收集单根管人离体牙33颗，选择EDTA、乙二醇二(β-氨基乙醚)-N，N，N’，N’-四乙酸[ethylene glycol bis(β—am—inoethvlether)一N,N,N’,N’-tetraacetic acid EGTA]、柠檬酸和H2O2 氯亚明四种冲洗剂比较，按不同浓度和pH值分为11组，3颗／组。离体牙截冠，常规根管预备，分别用不同冲洗剂2ml冲洗根管，劈开牙根，在扫描电子显微镜下观察根管壁去除玷污层的情况。结果 10％EGTA具有较好的冲洗效能。其中又以酸性的EGTA的根管清洁作用最好。此外，15％柠檬酸也具有较好的根管清洁作用。EGTA 氯亚明去除根管壁玷污层能力明显优于H2O2^ 氯亚明。结论 10％EGTA与氯亚明交替使用，效果可能更佳，是一种可替代H2O2^ 氯亚明的根管冲洗剂。     

不同根管封闭剂封闭性的研究进展

［摘要］ 根管封闭剂对实现良好而完善的根管充填起重要作用,它可以进入核心充填材料无法充填到的区域。目前应用于临床的根管封闭剂多种多样,而封闭性是决定根管充填效果至关重要的因素之一。该文对不同根管封闭剂的封闭性作一综述。     

Apical sealing ability of five endodontic sealers

Because apical leakage may be a cause of failure of endodontic treatment, the purpose of this study was to compare the apical seal provided by five endodontic sealers. After cleaning and shaping procedures, the root canals of 75 human cuspids were obturated by lateral condensation using gutta-percha and the following sealers: Kerr Pulp Canal Sealer EWT, Grossman's sealer, ThermaSeal, Sealer 26, and AH Plus. These root-filled teeth were then maintained at 37 degrees C and 100% humidity for two days. After immersion in a solution containing black India ink and fetal bovine serum for five days, the teeth were demineralised and rendered transparent. The extent of dye penetration was examined under a stereomicroscope. The results showed that Grossman's sealer exhibited significantly more leakage than the other sealers, except ThermaSeal. There was no significant difference between ThermaSeal and AH Plus. No significant differences were observed for Kerr Pulp Canal Sealer EWT when compared with either ThermaSeal or AH Plus. There was significantly less leakage for Sealer 26 when compared with the other sealers tested, except AH Plus.     

The influence of root canal shape on the sealing ability of two root canal sealers

AIM: To evaluate the influence of root canal form on the sealing ability of two root canal sealers. METHODOLOGY: Twenty radiographically confirmed straight and 20 curved root canals were prepared with a stepback hand filing technique. Root canal aberrations created during preparation were determined by the use of double exposure radiographic technique. The prepared canals were filled with lateral condensation of gutta-percha and one or other of two root canal sealers (Pulp Canal Sealer and Sealapex). Leakage along the apical 10 mm of roots was measured with a fluid transport model at 1, 3, 6, 9 and 12-month intervals. RESULTS: There were no statistically significant differences between straight and curved root canals (P > 0.05) for prevalence of root canal transportation. The prevalence of apical transportation was 80% in the straight and 85% in the curved root canals. A complete seal was more frequently observed in straight canals compared with curved canals. Utilizing the pi* index, analysis showed the filling with Sealapex allowed more leakage than Pulp Canal Sealer at 1 year. CONCLUSION: Under the conditions of the study, root canal form influenced short-term sealing ability. In the long-term the seal was affected by the sealer rather than root canal form.     

An evaluation of sealing ability of endodontic materials as root canal sealers

An in vitro dye leakage study was carried out to compare the apical microleakage of vitapex (calcium hydroxide based paste) when used with single gutta percha cone with that of dentalis KEZ (calcium hydroxide and zincoxide eugenol based sealer) and zincoxide-eugenol sealer when used with laterally condensed gutta percha obturation technique. One hundred single rooted human anterior teeth were instrumented and randomly divided into three experimental groups of 30 teeth each and two control groups of 5 teeth each. Teeth in the first group were obturated using a single master gutta percha cone and vitapex as root canal sealer and those of second group were obturated with laterally condensed gutta percha using dentalis KEZ as sealer. Third experimental group was filled with laterally condensed gutta-percha using zinc-oxide eugenol as sealer. Teeth were then suspended in 2% methylene blue. After this, teeth were demineralized dehydrated and cleared. Linear dye penetration was determined under stereomicroscope (x10) with calibrated eye piece. Results of this study showed that calcium hydroxide based endodontic material leaked comparatively less as compared to zinc oxide Eugenol sealer. Vitapex with single gutta-percha cone provided an adequate apical Seal against dye penetration.     

玷污层及封闭剂对Ultrafil-3D系统根尖封闭的影响

目的:观察有无玷污层及不同类型的封闭剂对Ultrafil-3D系统根管充填封闭性的影响。方法:64颗人离体单、直根管前牙预备后,将其中的60颗分为有玷污层与无玷污层组,各组分别采用3种封闭剂(AH-plus、Roekoseal、CRCS)并以Ultrafil-3D牙胶(Firmset)充填根管,其余4颗作为对照。所有标本在2%亚甲蓝中浸染5d,将牙体近远中向纵劈后,测量染料的线性染色长度。采用SAS6.04软件包进行方差分析及t检验。结果:(1)无论玷污层去除与否,CRCS组的微漏均显著大于AH-plus及Roekoseal组(P<0.05);(2)去除玷污层前后,使用3种封闭剂的染料微漏均无显著差异(P>0.05)。结论:AH-plus及Roekoseal与Ultrafil-3D牙胶联合使用,能增加根管充填的密合性,去除玷污层不能明显减少微漏的发生。     

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.     

The influence of the smear layer on dentinal tubule penetration depth by three different root canal sealers: an in vitro study

The effect of the smear layer on the penetration depth of three different root canal sealers into the dentinal tubules was examined in 64 recently extracted single-rooted teeth. After chemomechanical preparation, the samples were randomly divided in two equal groups. The smear layer remained intact in group A, whereas complete removal of the smear layer was performed in group B. Two roots from each group were used as controls. Ten roots from each group were obturated with laterally condensed gutta-percha points and sealers AH Plus, Apexit, and Roth 811, respectively. Examination in scanning electron microscope revealed that the smear layer obstructed all the sealers from penetrating dentinal tubules. In contrast, smear layer removal allowed the penetration of all sealers to occur to a varying depth. These findings suggest that smear layer plays an important role in sealer penetration into the dentinal tubules, as well as in the potential clinical implications.     

The effect of two different root canal sealers and smear layer on resistance to root fracture

The purpose of this in vitro study was to test the effect of Ketac-Endo (KE) and AH 26 on resistance to root fracture and also to evaluate the effect of smear layer. Seventy-two human maxillary canine teeth were randomly divided into six groups (n = 12) and were prepared using six different methods: group 1: KE, without smear layer (smear -); group 2: KE, with smear layer (smear +); group 3: AH 26, smear (-); group 4: AH 26, smear (+); group 5 (negative control): nonprepared; group 6 (positive control): prepared but unfilled. After storing 1 week in 100% humidity at 37 degrees C, the coronal lingual walls and root canal spaces were lowered 2 mm below the buccal walls of the roots. The samples were placed into acrylic resin blocks so that 10 mm of buccal roots were exposed and were placed in a specially designed steel pad at an angle of 15 degrees to the long axis of the root. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force required to fracture each tooth was recorded as kg and statistically analyzed using one-way analysis of variance and Duncan tests. The results indicated that instrumentation of the root canals significantly weakened the tooth structure to fracture (p < 0.05). The canals obturated with either sealer were significantly stronger than roots whose canals were instrumented but not obturated (p < 0.05), and there was no difference between the sealers. The presence or absence of the smear layer did not cause any significant effect on the root fracture resistance of the teeth (p > 0.05).     

Effect of smear layer on sealing ability of canal obturation: a systematic review and meta-analysis

The purpose of this systematic review was to determine whether smear layer removal reduces leakage of obturated human teeth in vitro. PubMed was searched for articles published between 1975 and 2005, and results were categorized based on the method of leakage test. Among 26 eligible papers with 65 comparisons, 53.8% of the comparisons reported no significant difference, 41.5% reported a difference in favor of removing the smear layer, and 4.7% reported a difference in favor of keeping it; differences were significant (p<0.001). Of the 65 comparisons, 44 used the dye leakage test for evaluation. The combined effect in this group showed smear layer removal decreases dye leakage (z-score=0.37, z=2.31, p=0.021). According to meta-regression, obturation type, test site and duration, sealer and dye, and publication year had no effect on the results. Under the conditions of these in vitro leakage studies, it is concluded that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer, did not produce significant effects.     

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。     

The influence of smear layer on coronal leakage of Roth 801 and AH26 root canal sealers

The aim of this in vitro study was to examine the effect of removal of smear layer on the coronal seal of two commonly used root canal sealers: Roth 801, a zinc oxide-eugenol-based sealer and AH26, an epoxy resin-based sealer. Ninety-six single-rooted human teeth were used. The teeth were instrumented and assigned to four experimental groups of 20 teeth each, with 10 teeth as controls and the remaining six teeth examined under a scanning electron microscope. The teeth in the experimental groups (80 teeth) were divided into four sub-groups and were obturated by laterally condensed gutta-percha with the two sealer cements as follows: Group A1: smear layer left intact and AH26 cement used as sealer; Group A2: smear layer left intact and Roth 801 cement used as sealer; Group B1: smear layer removed and AH26 cement used as sealer; and Group B2: smear layer removed and Roth 801 cement used as sealer. Coronal microleakage was evaluated by measuring the distance of dye penetration. The data was statistically evaluated using a two-way ANOVA test. The results showed that removal of the smear layer resulted in a statistically significant reduction of microleakage values in the groups obturated with AH26 compared with the groups obturated with Roth 801 sealer. It was concluded that the removal of smear layer has a significant influence on the degree of microleakage in obturated root canals.     

根管充填糊剂根尖封闭性的体外研究

目的：体外评价3种根管充填糊剂的根尖封闭效果。方法选取人离体下颌前磨牙68颗,截冠后随机分为A、B、C、D、E、F 6个组,其中A、B、C、D为实验组（每组12颗牙齿）,E和F分别为阳性和阴性对照组（每组各10颗牙齿）,所有样本均使用K3镍钛器械采用冠向下法完成根管预备后按如下方法进行根管充填：A、B组分别用树脂类根管充填糊剂AH Plus和生物陶瓷类根管充填糊剂iRoot SP行冷牙胶侧方加压充填;C、D组分别用生物陶瓷类根管充填糊剂iRoot SP和硅酮类根管充填糊剂Guttaflow行单尖充填;E、F组不添加糊剂只用牙胶尖侧方加压充填。将完成根管充填的实验组（每组10颗）和对照组浸入印度墨水中染色,其中4个实验组和阳性对照组在根尖孔周围2mm以外的牙体表面涂布2层指甲油,阴性对照组则在整个牙根表面涂布2层指甲油,采用透明牙法观察根尖微渗漏情况,使用imageJ软件测量并记录染色长度,并进行统计学分析;将剩余的样本横切后用扫描电镜对其截面进行观察。结果4个实验组所获得的浸墨长度分别为：A（1.02±0.46）mm, B（1.05±0.42）mm, C（1.02±0.45）mm, D（1.16±0.43）mm。4组浸墨长度之间的差异均无统计学意义（P〉0.05）。扫描电镜观察各组根管充填糊剂和根管壁牙本质之间均有缝隙。结论3种根管充填糊剂均不能完全封闭根管,在根尖封闭效果上无明显差异。     

Effect of three different sealers on the sealing ability of both thermafil obturators and cold laterally compacted Gutta-Percha

The purpose of this study was to assess the seal obtained in straight and curved root canals filled with either laterally compacted gutta-percha or Thermafil obturators. Each technique was used in combination with three different sealers (RSA RoekoSeal, AH Plus, AH 26). Thermafil obturators were also used without sealer, resulting in a total of 14 test groups of 16 teeth each. Sixty teeth served as positive or negative controls. Included in the study were 142 extracted teeth with straight and 142 with curved root canals. All canals were enlarged up to size 40. After obturation, all roots were placed in India ink for 48 h and rendered transparent to measure the maximum linear dye penetration. Canals filled with Thermafil obturators had significantly more extrusion of filling material than canals filled by lateral compaction (p < 0.01). Thermafil without sealer showed significantly greater dye penetration compared with all other groups both in straight and in curved canals (p < 0.05). As long as a sealer was used, the seal obturated with Thermafil was equivalent in terms of dye penetration to lateral compaction. There were no statistical differences in the mean apical dye penetration among the three sealers. The differences between the dye penetration in straight and in curved canals were insignificant for all groups (p > 0.05). Under the conditions of this study, Thermafil obturators achieved seals comparable to lateral compaction, as long as a sealer was used.     

In vivo sealing ability of calcium hydroxide-containing root canal sealers

Abstract It was the purpose of this study to determine the sealing ability of 2 commercially available calcium hydroxide-containing root canal sealers, CRCS and Sealapex. One hundred sixty single-rooted human teeth were used. The clinical crowns were removed and the roots were cleaned mechanically and by immersion for 24 h in 5% sodium hypochlorite. The root canals were then instrumented to size 80 at the apical foramen and the roots were sterilized by γ-radiation. Under aseptic conditions the root canals were filled with a gutta-percha master cone size 70 and Sealapex (48 roots), CRCS (48 roots), and a zinc oxide-eugenol type sealer, Roth 801 (50 roots). The coronal aspects of the root canals were then sealed with zinc oxide-eugenol cement. In order to bring the roots and root filling materials in contact with tissue and tissue fluids, the roots were implanted subcutaneously in rabbits for 90 days and 1 year. Leakage as demonstrated by penetration of India ink was evaluated using a stereomicroscope. The best results were obtained with CRCS. Significantly less leakage occurred with both calcium hydroxide-containing sealers than with the traditional zinc oxide-eugenol sealer.