The effect of smear layer on microbial coronal leakage of gutta-percha root fillings

The aim of this in vitro study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction. One hundred and twenty extracted human teeth with straight, single root canals were decoronated. The canals were prepared using the modified double-flared technique with balanced force under copious irrigation. The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 15 file. The teeth were divided randomly into experimental groups (80 teeth) and control groups (40 teeth). The root canals of 40 experimental and 20 control teeth were rinsed with 40% citric acid and 2% NaOCl to remove the smear layer before obturation. In experimental groups, 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with lateral condensation of cold gutta-percha and Apexit sealer. A further 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with the Trifecta technique with the same sealer. In control groups, 10 teeth with smear layer intact and 10 teeth with smear layer removed were obturated with lateral condensation of cold gutta-percha and Apexit sealer. These teeth were completely sealed both coronally and apically to serve as negative controls. The remaining 20 teeth with either smear layer intact or smear layer removed were not obturated and served as the positive controls. The root surface of each tooth was sealed with nail varnish. The cut end of a polypropylene tube was sealed around the coronal part of each root canal so that bacteria placed therein could move only through the obturated canal space. Each root was placed in a glass bottle containing sterile Todd-Hewitt Broth (THB) and aliquots of 0.5 ml of THB were injected into the polypropylene tube. The model system was centrifuged at 168 g. An innoculum of Streptococcus sanguis in THB was placed in each coronal chamber at 5-day intervals and daily observations were made for bacterial growth in the apical reservoir for 90 days. All positive control teeth showed bacterial penetration within 24 h, while the negative control teeth remained uncon-taminated throughout the test period. Leakage through the experimental teeth was variable ranging from 7 to 86 days. There was no statistical significant difference (P > 0.05) in leakage between the obturated canal when the smear layer was either removed or intact.     

An in-vitro study of smear layer removal and microbial leakage along root-canal fillings

The objective of this study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction. Fifty-four extracted human teeth were decoronated and instrumented in a uniform manner. Following instrumentation the root canals of 20 teeth were rinsed with 17% EDTA and 5.25% NaOCl to remove the smear layer before obturation. A second group of 20 teeth were flushed with NaOCl alone. The teeth of both groups were obturated with Thermafil^TM plastic carriers and Roth's sealer. The root canals of another 10 teeth, five rinsed with EDTA and five without, were obturated with Thermafil^TM without sealer. Two teeth serving as positive controls were instrumented but not obturated, while another set of two were sealed coronally and apically to serve as negative controls. The root surface of each tooth was sealed with nail varnish. A small chamber was thoroughly sealed around the coronal aspect of each tooth so that bacteria placed therein could move only through the obturated canal space. Each tooth was placed in a test tube containing sterile trypticase soy broth (TSB). An inoculum of Proteus vulgaris in TSB was placed in each coronal chamber at five day intervals and daily observations were made for bacterial growth in the apical reservoir for 21 days. Both positive control teeth showed bacterial penetration after 24 h. Neither of the two negative control teeth demonstrated penetration for the duration of the study. The frequency of bacterial penetration through teeth obturated with intact smear layer (70%) was significantly greater than that of teeth from which the smear layer had been removed (30%) P< 0.05. All but one tooth obturated without sealer exhibited bacterial penetration, irrespective of the presence or absence of smear layer. Removal of the smear layer enhanced sealability as evidenced by increased resistance to bacterial penetration.     

An evaluation of microbial leakage after using MTAD as a final irrigation

Cleaning the root canal is not possible without using proper irrigation. The aim of this in vitro study was to evaluate the effect of MTAD as a final irrigant on bacterial leakage of the root canal, and its interaction with two conventional root canal sealers. We used 132 extracted human maxillary anterior teeth. The teeth were randomly divided into three experimental groups (n=40) and two groups (n=6) of positive and negative control. In group 1, the smear layer was not removed and irrigation was performed using 5.25% NaOCl. In group 2, the smear layer was removed using EDTA, and in group 3, the smear layer was removed using MTAD according to the clinical protocol of use. The teeth in each group were obturated with gutta-percha and AH-Plus or Rickert sealer. The coronal portion of each root was placed in contact with inoculum of Streptococcus mutans in Brain Heart Infusion (BHI) culture media. Each root tip was placed in one bottle containing sterile BHI. Mean duration of bacterial penetration in groups 2 and 3 was significantly greater than in group 1, but there was no significant difference between groups 2 and 3. According to our findings, it takes longer for bacteria to penetrate when either EDTA or MTAD is used for smear layer removal. The root canals obturated with AH Plus showed significantly longer duration of resistance to bacterial penetration than canals obturated with Rickert.     

Sealability of the Trifecta™ technique in the presence or absence of a smear layer

The aim of this in vitro study was to assess the sealability of a recently introduced thermoplasticized gutta-percha technique (Trifecta, Hygenic Corp., OH, USA) in the presence or absence of a smear layer. A total of 100 teeth with single straight root canals were included in the study. The teeth were decoronated and the canals prepared with a modified double-flared technique under constant irrigation with 2.5% sodium hypochlorite solution. The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 10 file. Four teeth were discarded for technical reasons and the remaining 96 allocated randomly into two groups of 44 teeth and a group of eight teeth which acted as controls. Canals in group 1 were obturated randomly with either cold lateral condensation of gutta-percha or with the Trifecta technique. Canals in Group 2 were rinsed with 17% REDTA to remove the smear layer and then obturated with lateral condensation or the Trifecta technique. All teeth were suspended in India ink for 9 days, demineralized, and rendered transparent prior to the assessment of apical linear dye penetration. Apical extrusion of sealer and gutta-percha occurred commonly but there was no significant difference between the four obturation groups. However, overall, there was significantly more extrusion of sealer with the Trifecta technique compared with lateral condensation (P<0.05). The majority of canals (79 out of 88) had no evidence of apical leakage and there was no significant difference between the groups. The prevalence of sealer and gutta-percha penetration into the dentinal tubules was significantly different between the four obturation techniques (P<0.01) and significantly more common in the absence of the smear layer (P<0.001). Under the conditions of this study, the Trifecta technique     

Comparative study of apical sealing ability of a new resin-based root canal sealer

The purpose of this study was to compare the microleakage of two root canal sealers, Fibrefill (resin-based sealer) and calciobiotic root canal sealer (CRCS; calcium hydroxide-based sealer), with and without the presence of smear layer. The model used for the measurement of microleakage was a fluid transport model.Sixty human extracted teeth were used in this study. The teeth were divided into four groups and treated as follows. In group A, the smear layer was left intact, and canals were obturated with gutta-percha and Fibrefill. In group B, the smear layer was removed, and canals were obturated with gutta-percha and Fibrefill. In group C, the smear layer was left intact, and the canals were obturated with gutta-percha and CRCS. In group D, the smear layer was removed, and canals were obturated with gutta-percha and CRCS. Microleakage was measured at 7 days, 1 month, and 2 months.The results showed that the Fibrefill groups with and without smear layer leaked significantly less than the CRCS groups at all experimental times. No significant difference was found between the groups of same materials, but the microleakage values were less when the smear layer was removed.     

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.     

Push‐out bond strength of gutta‐percha with a new bioceramic sealer in the presence or absence of smear layer

The purpose of this study was to compare the bond strength of a new bioceramic sealer (EndoSequence BC Sealer) and AH Plus in the presence or absence of smear layer. Extracted single‐rooted human teeth were prepared and randomly divided into four groups. In groups 1 and 3, the root canals were finally irrigated with 5.25% NaOCl and smear layer was not removed, but in groups 2 and 4, the root canals were finally irrigated with 17% EDTA followed by 5.25% NaOCl in order to remove the smear layer. In groups 1 and 2, the root canals were obturated with gutta‐percha/AH Plus, but in groups 3 and 4, obturation was performed with gutta‐percha/EndoSequence BC Sealer. Push‐out bond strength and failure modes were evaluated. The bond strength of gutta‐percha/AH Plus and gutta‐percha/EndoSequence BC Sealer was not significantly different (P = 0.89). The presence or absence of smear layer did not significantly affect the bond strength of filling materials (P = 0.69). The mode of bond failure was mainly cohesive for all groups. In conclusion, the bond strength of the new bioceramic sealer was equal to that of AH Plus with or without the smear layer.     

Long-term evaluation of the influence of smear layer removal on the sealing ability of different sealers

The purpose of this study was to examine the effect of the smear layer on apical microleakage over 16 wk. One hundred and four extracted human teeth were assigned to four groups treated as follows: group A1--smear layer was left intact and canals were obturated with gutta-percha and Roth 811; group A2--smear layer was left intact and canals were obturated with gutta-percha and AH26; group B1--smear layer was removed and canals were obturated with gutta-percha and Roth 811; and group B2--smear layer was removed and canals were obturated with gutta-percha and AH26. Microleakage was measured by the electrochemical method. In parallel, 12 teeth were examined under a scanning electron microscope. The results indicated that the smear layer removal resulted in a statistically significant reduction of microleakage values in groups obturated with AH26. The presence or absence of smear layer had no significant effect on the sealing ability of Roth 811.     

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.     

Comparison of cold lateral condensation and a warm multiphase gutta-percha technique for obturating curved root canals

AIM: The aim of this project was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or multiphase gutta-percha obturation (Alphaseal). METHODOLOGY: A total of 108 freshly extracted human, mature single-rooted teeth were divided into two identical groups of 54 teeth on the basis of root canal shape. The canals were prepared to a minimum 0.055 taper and enlarged to size 35 at the apex. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one group were obturated using cold lateral condensation of gutta-percha and the canals of the other group were filled using a warm multiphase gutta-percha obturation technique. The extrusion of sealer and/or gutta-percha through the apex of the teeth was recorded using a simple yes/no scheme. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a four-point scale. RESULTS: Root canals filled by multiphase obturation had significantly more extrusion of sealer (P < 0.001) and gutta-percha (P < 0.001) than canals filled by lateral condensation. Canals filled by multiphase gutta-percha obturation had significantly less apical dye leakage than those obturated by lateral condensation (P < 0.05). Lateral condensation achieved significantly better scores for radiographic quality than multiphase obturation from the bucco-lingual view (P < 0.01). CONCLUSIONS: Under laboratory conditions multiphase gutta-percha had better sealability but poorer radiographic quality than lateral condensation.     

Comparative study of the sealing ability of a polydimethylsiloxane-based root canal sealer

The purpose of this study was to compare the sealing ability of three root canal sealers, RSA (polydimethylsiloxane sealer), Endion (glass-ionomer sealer) and Topseal (epoxy resin sealer), with and without smear layer removal. Ninety extracted human teeth were selected and assigned to 6 groups (n=15), according to the following protocols: in 3 groups, the smear layer was left intact and the root canals were obturated with gutta-percha points and RSA, Endion and Topseal, respectively; in the other 3 groups, the smear layer was removed and the root canals were obturated in the same way as described above. Microleakage was measured at 7 days, 1 month and 2 months, using the fluid transport model. The results were expressed in microL/24 h. Data were analyzed statistically by Kruskall-Wallis and Mann-Whitney non-parametric tests. The results showed that the Topseal group without smear layer leaked significantly less (p<0.05) than the RSA group without smear layer, at all experimental periods. No statistically significant differences (p>0.05) were found among the other groups, at the established evaluation intervals. The findings of this study showed that the polydimethylsiloxane sealer (RSA) did not yield better sealing ability than the other sealers, either in the presence or in the absence of smear layer. Topseal had the least microleakage from the root canal sealers evaluated.     

5种根管充填糊剂的根管封闭能力的比较

目的：比较5种根管充填糊剂的根管封闭能力。方法：选择75个直根管的恒牙,经开髓拔髓,Mtwo镍钛根管器械预备后反复冲洗后随机分为5组,分别采用实验组1：氧化锌丁香油糊剂,实验组2：Endomethasone根管充填糊剂,实验组3：Cortisomol根管充填糊剂,实验组4：Vitapex糊剂,实验组5：AH-plus糊剂,加牙胶尖严密充填。将所有离体牙置于37℃,100%湿度的恒温箱3d后选用透明牙染色法测量微渗漏深度。结果：实验组1：（2.35±0.768）mm,实验组2：（1.78±0.548）mm,实验组3：（1.54±0.322）mm,实验组4：（3.22±0.452）mm,实验组5：（0.98±0.536）mm。各组微渗漏深度值差异有显著性（P〈0.05）。其中实验组4的微渗漏值显著高于其他各组（P〈0.05）,实验组5的微渗漏值显著低于其他各组（P〈0.05）,实验组2的微渗漏值稍高于实验组3,结果无显著差异。结论：在Mtwo镍钛器械预备下,AH-Plus糊剂充填根管可有效的减少根管微渗漏的发生,但长远疗效有待进一步的观察。     

A comparison of techniques for assessment of coronal dye leakage.

This study was designed to compare different techniques for coronal dye leakage testing. One hundred and fifty extracted human anterior teeth were fully instrumented and randomly divided into two experimental groups of 60 teeth each, plus two groups of 15 teeth each for positive and negative controls. One group was rinsed with 5.25% NaOCl (smear layer intact), whereas the other group was flushed with 17% EDTA and 5.25% NaOCl (smear layer removed). Roots were obturated with gutta-percha using lateral condensation and AH Plus as root canal sealer. Each experimental group was divided into three subgroups of 20 teeth each for three methods of testing coronal dye leakage: passive dye penetration, penetration with vacuum applied, and fluid filtration methods. The teeth were left in 100% humidity at 37 degrees C for 5 days before being immersed in Indian ink for 2 days and cleared. The linear extent of dye penetration was measured. Mean depth of leakage for the groups with the smear layer intact was 2.5 +/- 1.0 mm for passive dye penetration, 6.7 +/- 2.8 mm for vacuum dye penetration, and 3.0 +/- 1.1 mm for fluid filtration dye penetration. In the group in which the smear layer was removed, the mean depths of leakage were: 3.2 +/- 2.1 mm for passive dye penetration, 5.8 +/- 2.8 mm for vacuum dye penetration, and 3.4 +/- 2.1 mm for fluid filtration. The vacuum method resulted in significantly (p < 0.05) more dye penetration than fluid filtration and passive dye penetration. The presence or absence of smear layer had no statistically significant effect (p > 0.05) on any of the leakage testing techniques.     

Comparison of lateral condensation and thermomechanically compacted warm alpha-phase gutta-percha with a single cone for obturating curved root canals

OBJECTIVE: To evaluate and compare the sealability and radiographic quality of root fillings in extracted teeth by using lateral condensation of gutta-percha or alpha-phase gutta-percha in conjunction with a single gutta-percha cone. STUDY DESIGN: A total of 108 single-rooted teeth were divided into 2 groups of 54 teeth based on canal shape. Canals were prepared to a minimum 0.055 taper and enlarged to a size 35 at the working distance. Irrigation was done with 17% EDTA and 2.5% sodium hypochlorite (NaOCl) to remove smear layer. One group was obturated by using cold lateral condensation of gutta-percha; the other group was obturated with thermomechanically compacted alpha-phase gutta-percha and a single cone of gutta-percha. Apical extrusion of sealer or gutta-percha was recorded. Sealability of each technique was assessed by dye penetration. The radiographic quality of obturation was also determined. RESULTS: Root canals filled with alpha-phase gutta-percha and a single cone had significantly more extrusion of sealer than canals filled by lateral condensation. Lateral condensation achieved significantly better scores for radiographic quality. There was no significant difference between the 2 filling techniques in terms of apical or coronal leakage. CONCLUSIONS: Thermomechanically condensed alpha-phase gutta-percha used in conjunction with a single gutta-percha cone had poorer radiographic quality than laterally condensed gutta-percha.     

Evaluation of the Trifecta obturating technique

The aim of this project was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta-percha or the Trifecta obturating system. One hundred freshly extracted human mature, single-rooted teeth were divided into four identical groups of 25 teeth on the basis of root canal shape. The root canals of two groups were prepared in such a way as to produce a relatively parallel canal shape with little or no flare towards the coronal orifice. The root canals of the other two groups were prepared in such a way as to produce a canal shape that was deliberately more flared to ensure that they were wider at the orifice than at the endpoint of the preparation. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one flared and one parallel group were obturated using cold lateral condensation and the canals of the other two groups were obturated using the Trifecta system. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a 4-point scale. Canals filled with thermoplasticised gutta-percha had significantly less apical dye penetration than those obturated by lateral condensation (P < 0.001). Lateral condensation achieved significantly better scores for radiographic quality than thermoplasticised gutta-percha from both the bucco-lingual (P < 0.001) and the mesio-distal views (P < 0.001). Root canals obturated using the Trifecta technique showed significantly more apical extrusion of sealer than those obturated by lateral condensation (P < 0.001). Under laboratory conditions the Trifecta technique had better sealability but poorer radiographic quality than lateral condensation.     

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.     

Evaluation of the Trifecta obturating technique

Abstract – The aim of this project was to evaluate and compare the radiographic quality and sealability of root fillings in extracted human teeth using lateral condensation of gutta‐percha or the Trifecta obturating system. One hundred freshly extracted human mature, single‐rooted teeth were divided into four identical groups of 25 teeth on the basis of root canal shape. The root canals of two groups were prepared in such a way as to produce a relatively parallel canal shape with little or no flare towards the coronal orifice. The root canals of the other two groups were prepared in such a way as to produce a canal shape that was deliberately more flared to ensure that they were wider at the orifice than at the endpoint of the preparation. All root canals were flushed with 17% EDTA solution and 2.5% NaOCl to remove the dentinal smear layer. The canals of one flared and one parallel group were obturated using cold lateral condensation and the canals of the other two groups were obturated using the Trifecta system. The sealability of each technique was assessed by a dye penetration method. The radiographic quality of obturation was determined for each canal using a 4‐point scale. Canals filled with thermoplasticised gutta‐percha had significantly less apical dye penetration than those obturated by lateral condensation (P<0.001). Lateral condensation achieved significantly better scores for radiographic quality than thermoplasticised gutta‐percha from both the bucco‐lingual (P<0.001) and the mesio‐distal views (P<0.001). Root canals obturated using the Trifecta technique showed significantly more apical extrusion of sealer than those obturated by lateral condensation (P<0.001). Under laboratory conditions the Trifecta technique had better sealability but poorer radiographic quality than lateral condensation.     

Application of biologically-oriented dentin bonding principles to the use of endodontic irrigants

PURPOSE: To compare the removal of smear layer and the structure of the hybrid layer formed after the use of EDTA or MTAD solutions when used as a final flush. METHODS: Single-rooted extracted premolars (n=18) were collected and treated for root canal therapy using NaOCl irrigation followed by a final rinse of 17% EDTA, Biopure MTAD, or saline (negative control). The roots were obturated with gutta-percha and a hydrophilic HEMA-containing root canal sealer. The TEM specimens were impregnated with 50% silver nitrate to visualize sealing imperfections and nanoleakage. The structure of the coronal, middle and apical parts of root canal walls was examined using transmission electron microscopy. RESULTS: After NaOCl irrigation, a final rinse with BioPure MTAD or 17% EDTA completely removed the 2 microm-thick smear layer on mechanically instrumented root canal walls. The BioPure MTAD hybrid layer was thicker than the 17% EDTA hybrid layer. Both the BioPure MTAD and EDTA caused a collapse of the dentin matrix structure which impeded sealer infiltration and the formation of high quality hybrid layer bonding. The hybrid layers created in smear layer-covered dentin exhibited less potential for nanoleakage than the MTAD or EDTA hybrid layers.     

Apical and coronal seal of roots obturated with a dentine bonding agent and resin

The efficacy of sealing root canal systems with a dentine bonding agent and resin cement was compared with that of a glass ionomer sealer. Scanning electron microscopic examination of the bonding agent-dentine interface was also performed. The root canals of 50 single rooted teeth with mature apices were prepared chemo-mechanically and the smear layer removed with 17% REDTA and 5.25% NaOCl. Specimens were divided into two groups of 24 teeth each. One group had the dentine conditioned with a 10:3 citric acid-ferric chloride solution and obturated with the dentine bonding agent and resin, radiopaque C & B Metabond. The other group was obturated with the glass ionomer sealer, Ketac-Endo and a single cone of gutta-percha. After immersion in Indian ink for 90 h, the teeth were cleared and the quality of the apical and coronal seal was assessed using India ink dye penetration. There was a significantly better seal in both the apical and coronal directions when using the dentine bonding agent and resin obturation material. Scanning electron microscopic examination of the demineralized dentine and the C & B Metabond interface revealed the presence of the characteristic hybrid layer along with microtags of resin penetrating deep into the dentine tubules.     

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。