去除玷污层对根管微渗漏影响的实验研究

目的评价去除玷污层对根管充填材料密封性能的影响.方法选取60个新鲜拔除的人单根管牙,在釉牙骨质界处切除牙冠.将所有牙根随机分为3组,每组20个.分别用根管充填糊剂加牙胶尖、Vitapex糊剂加牙胶尖和Thermafil糊剂热熔牙胶充填根管;每组中有10个牙根根管预备时保留玷污层,另外10个去除玷污层.用印度墨水染色法对比研究去除玷污层对根管充填材料密封性能的影响.结果牙胶尖加根管充填糊剂组中,保留和去除玷污层组的染色线长度均值分别为3.36±0.42 mm、3.42±0.65 mm;Vitapex加牙胶尖组中,染色线长度均值分别为2.09±0.19 mm、1.70±0.22 mm;Thermafil热熔牙胶组中,染色线长度均值分别为1.05±0.37 mm、0.56±0.11 mm.统计学分析发现3个实验组中,去除玷污层或保留玷污层对根管微渗漏影响的统计学差异均不显著(P>0.05).结论去除玷污层对根管充填材料的密封性能无显著影响.     

玷污层对根尖微渗漏的影响

目的:利用扫描电镜和葡萄糖定量法评价玷污层对离体牙根管充填后根尖微渗漏的影响.方法:选取51颗单直根管离体牙,随机分为5组进行根管预备,并按分组进行根管冲洗.A组(11颗)--17%乙二胺四乙酸和1%次氯酸钠,B组(11颗)--1%盐酸四环素和1%次氯酸钠,C组(11颗)--10%枸橼酸和1%次氯酸钠,D组(9颗)--1%次氯酸钠.E组(9颗)--生理盐水.每组各选取1个样本进行扫描电镜观察,其余样本进行根管侧压充填.于第1、2、4、7、10、15、20、30天用葡萄糖氧化酶法测定从冠方向根方渗漏的葡萄糖量.实验数据采用SPSS16.0软件包进行重复测量数据的方差分析和SNK-q检验.结果:A、B、C组根管无玷污层结构,微渗漏量较D、E组小(P<0.05);D、E组根管玷污层多,微渗漏量大,E组微渗漏量大于D组(P<0.05).结论:去除玷污层可有效减少微渗漏的发生.     

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。     

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。     

Effect of smear layer removal on bleaching of human teeth in vitro

The purpose of this study was to evaluate objectively in vitro the effectiveness of bleaching artificially discolored teeth with or without the smear layer present using sodium perborate mixed with sterile water or 35% hydrogen peroxide (H2O2). Seventy fully developed maxillary anterior teeth were artificially stained with human hemoglobin and separated into one control and four experimental groups. After the smear layer was removed on half the experimental teeth and left intact on the other half, all of the teeth were bleached intracoronally with sodium perborate and 35% H2O2 or sodium perborate plus water. The bleaching agents were applied twice over a 6-day period. The changes in tooth shade were objectively analyzed using a SP78 sphere spectrophotometer at 1, 30, and 60 days postbleaching. The presence or absence of the smear layer did not significantly influence the outcome of bleaching (p > 0.05). The teeth bleached with sodium perborate and 35% H2O2 were significantly lighter than the teeth bleached with sodium perborate and sterile water (p < 0.0001) at each experimental period. Based on the findings of this study, it is not advantageous to remove the smear layer before intracoronal bleaching.     

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。     

Effect of smear layer removal agents on the microhardness and roughness of radicular dentin

PurposeTo evaluate the effect of phytic acid (IP6) on the surface roughness and microhardness of human root canal dentin and compare it to other smear layer removal agents.Materials and methodsFifty extracted human maxillary incisors were sectioned longitudinally into a total of 100 specimens followed by embedding in auto-polymerizing acrylic resin. The specimens were polished and then randomly divided into five groups (n = 20) according to the test solution used to condition root canal dentin: 17% ethylenediaminetetraacetic acid (EDTA); 10% citric acid (CA); 1% IP6; 37% phosphoric acid (PA); or distilled water (control group). Each specimen was treated with a total volume of 1 ml of each solution for 1 min with agitation. Each group was then divided into two subgroups of 10 specimens each. The specimens of the first subgroup were used to determine microhardness, using Vickers hardness tester, and the specimens of the second subgroup were used to measure surface roughness, using a confocal laser scanning microscope. The results were analyzed statistically using one-way ANOVA and Tukey tests, α = 0.05.ResultsAll the tested groups exhibited microhardness and surface roughness values that were statistically significantly different when compared with the control group (P < 0.05). The microhardness value obtained with IP6 was significantly lower when compared to EDTA, CA, and the control group, whereas its roughness value was significantly higher compared to the aforementioned groups. However, there was no significant difference between IP6 and PA (P > 0.05).ConclusionsIP6 and PA showed the lowest microhardness and the highest surface roughness values.     

玷污层及不同根管封闭剂对根管充填后根尖微渗漏的影响

目的:评估玷污层、根管封闭剂对根管充填后微渗漏的影响。方法:选择新鲜拔除的根尖发育完成的单根管人前牙,常规预备根管,随机分4组:A(AH-plus),B(Apexit),C(氧化锌丁香油糊剂),D(根管糊剂),各组内再分为1、2组,1组在充填前用170g/LEDTA和52.5g/L次氯酸钠溶液交替冲洗以去除玷污层,2组仅用52.5g/L次氯酸钠溶液冲洗,所有牙采用侧方加压法充填根管后,在冠方插入铜丝使其与牙胶接触,浸入生理盐水溶液中,在每牙与一不锈钢电极间加12V的直流电,观察40d,用单因素方差分析和LSD-t检验比较10、20、30、40d时的数据。结果:AH-plus、Apexit产生的微渗漏低于氧化锌丁香油糊剂、根管充填糊剂,而AH-plus又低于Apexit,去除玷污层使AH-plus产生低的微渗漏值。结论:AH-plus、Apexit的封闭能力优于氧化锌丁香油糊剂、根管充填糊剂,去除玷污层能增加AH-plus的封闭能力。     

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 EDTA with and without surfactants or ultrasonics on removal of smear layer

This study compared the in vitro efficacy of Smear Clear (Sybron Endo, CA), a 17% ethylenediaminetetraacetic acid (EDTA) solution with surfactants, to 17% EDTA, with and without the use of ultrasonics, in removal of the smear layer. Seventy-five extracted teeth, randomly distributed into 5 test groups, were prepared by using ProFile rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) and subjected to different final irrigating regimes; group A, 1% sodium hypochlorite; group B, 17% EDTA; group C, 17% EDTA with ultrasonics; group D, Smear Clear; and group E, Smear Clear with ultrasonics. Samples were examined under the scanning electron microscope and scored for debris and smear layer removal. Statistical analysis showed that groups D and E did not perform significantly better than groups B and C. Group C performed significantly better than group B. Addition of surfactants to EDTA in Smear Clear did not result in better smear layer removal. The use of ultrasonics with 17% EDTA improved smear layer removal.     

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.     

The effect of smear layer removal on marginal contraction gaps

The presence of the smear layer prevents direct contact between dentine and a dentine adhesive. The use of agents to remove the smear layer theoretically should improve the bonding of composite resins to dentine. This study examined the effect of smear layer removal on the effectiveness of a dentine bonding agent in reducing marginal contraction gaps. The agent used for smear layer removal in this study was ethylenediamine tetra-acetic acid (EDTA). Eighty cavities measuring 2mm in diameter and 1.5 mm in depth were prepared in dentine and randomly assigned to two equal groups. The control group was restored with Prisma Universal Bond 2 Adhesive and Prisma Fil Resin. The experimental group was similarly restored after pretreatment of dentine with 0.5% EDTA for 60s. All specimens were thermocycled and the marginal contraction gaps were assessed using a Nikon Measurescope. The mean contraction gap was expressed as a percentage of the cavity diameter. Results showed that the experimental group registered smaller contraction gaps (mean: 0.021%) than the control group (mean: 0.027%). No penetration of material into dentine was observed. Pretreatment with EDTA did not significantly improve the effectiveness of the dentine bonding agent used in terms of reduction of marginal contraction gaps.     

Effect of the sodium hypochlorite and citric acid association on smear layer removal of primary molars

This study aimed to assess the capacity of a sodium hypochlorite and citric acid (CA) association (the latter at different concentrations) in removing coronal smear layer (SL) of primary teeth. For this purpose, the pulp chamber roof and floor of 28 primary molars were removed to obtain enamel and dentine disks. SL was produced on the internal walls of the disks using high-speed drills. The disks were irrigated with 1% sodium hypochlorite and citric acid at different concentrations (CA-4%, CA-6%, CA-8% and CA-10%), and with 0.9% sodium chloride. The samples were split and observed under SEM. Scores were attributed to the obtained photomicrographs, according to the amount of SL present. It was noted that all the tested concentrations of citric acid used after the sodium hypochlorite were capable of removing SL. The results were analyzed by the Kruskal-Wallis test, and there was no significant statistical difference among the scores of the groups tested. However, it was observed that CA-8% and CA-10% caused peritubular dentine destruction, and that CA-4% presented a larger number of samples with dense SL. Based on these results, 6.0% citric acid in association with 1% sodium hypochlorite is suggested as auxiliary chemical substances for primary teeth irrigation.     

次氯酸钠配合SmearClear清除根管玷污层的研究

目的:比较4种根管冲洗方法清除根管玷污层的效果,研究出有效去除根管玷污层的方法。方法:20个无龋单根前牙随机分为4组,A组:60℃30 g/L次氯酸钠液加170 g/L EDTA,#15K锉提拉冲洗;B组:60℃30 g/L次氯酸钠液加SmearClear,#15K锉提拉冲洗;C组:60℃30 g/L次氯酸钠液加170 g/LEDTA液超声荡洗;D组:60℃30 g/L次氯酸钠液加SmearClear超声荡洗。扫描电镜下放大2 500倍和4 000倍观察根尖1/3、根中1/3和根上1/3玷污层清除情况。按照根管壁玷污层清除情况和根管壁腐蚀程度的分级标准进行统计学分析。结果:①根管壁玷污层清除情况:4组在根上2/3区玷污层均有效去除,各组间差异无统计学意义(P>0.05),B组根尖1/3基本无玷污层,A、C、D组仅见少部分玷污层被去除,B组与A、C、D组差异有统计学意义(P<0.05);②根管壁腐蚀性比较:C、D组根上2/3区腐蚀度较大,而A、B组未见明显腐蚀。C、D组与A、B组相比差异有统计学意义(P<0.05),各组根尖1/3根管壁腐蚀度差异无统计学意义(P>0.05)。结论:SmearClear与60℃30 g/L次氯酸钠液联合应用能更有效的去除根管玷污层,且对根管壁表面结构无明显破坏。     

An apical leakage study in the presence and absence of the smear layer

The apical seal produced by low-temperature injection of gutta-percha, with or without root canal sealer, in the presence or absence of the smear layer was evaluated quantitatively using an electrochemical technique. The root canals of 44 teeth were prepared with the smear layer intact following a final flush of NaOCl (group 1), while the root canals of a further 44 teeth were prepared and the smear layer removed with a final flush with EDTA followed by NaOCl (group 2). Subgroups were obturated using Ultrafil System alone or accompanied by Calciobiotic Root Canal Sealer. Microleakage data was expressed as a percentage of apical leakage evident in each group. Statistical analysis of the results revealed that the groups obturated with Ultrafil alone showed no significant differences in leakage compared with the groups where sealer was used, either when the smear layer had been left intact or removed. (P>0.05). However, comparison of the combined two groups with smear layer present versus the combined two groups with smear layer removed showed a highly significant difference (P<0.01), with the incidence of leakage reduced in the absence of the smear layer.