Evaluation of microleakage following application of a dentin bonding agent as root canal sealer in the presence or absence of smear layer

Effect of the smear layer on apical seals produced by two calcium silicate-based endodontic sealers

We compared the apical seals of two new calcium silicate-based sealers (iRoot SP and MTA Fillapex) in the presence and absence of a smear layer. Eighty-two human premolars were prepared and randomly divided into four groups. In groups 1 and 3, the smear layer was retained. In groups 2 and 4, the root canals were irrigated with EDTA to remove the smear layer. Canals were filled using gutta-percha/iRoot SP (in groups 1 and 2) or obturated with gutta-percha/MTA Fillapex (in groups 3 and 4). Fluid filtration was used to evaluate apical microleakage. The presence of the smear layer had no significant effect on the sealing properties of the filling materials, except for iRoot SP at 2 weeks (P = 0.007). There was significantly less microleakage with iRoot SP than with MTA Fillapex (P = 0.025 at 2 weeks; P < 0.001 at 3 months). Leakage decreased significantly over time in all specimens, except in group 2 (P = 0.473). In conclusion, removal of the smear layer had no adverse effect on the sealing properties of calcium silicate-based sealers. In addition, the sealing ability of iRoot SP was superior to that of MTA Fillapex.

Evaluation of the dentinal wall adaptation ability of MTA Fillapex using stereo electron microscope

Background:

An ideal root canal obturation requires a complete dentinal wall adaptation of sealer and Gutta-percha combinations without any gap formations.

Aims:

The aim of the study was to evaluate the dentinal wall adaptation ability of MTA Fillapex root canal sealer using stereo electron microscope (SEM).

Methods:

Twenty-four, single-rooted, human maxillary incisor teeth were used. All canals were prepared with a rotary nickel–titanium (Ni–Ti) instrument to a size F3 file. Teeth divided into two equal groups and one of the experimental groups was filled with AH Plus, and the other group was filled with MTA Fillapex using Gutta-percha single cone as a core material. The roots were prepared for SEM evaluation, and serial scanning electron photomicrographs were taken at ×50, ×100, ×500, and ×1000 magnifications. The gaps between the root canal sealer and canal walls were detected and measured in coronal, middle, and apical thirds. For each section, the highest value among the detected gap formations was recorded.

Statistical Analysis:

Mann–Whitney U-test, Freidman, and Wilcoxon tests were used.

Results:

The statistical analysis showed no significant difference between two sealers in terms of gap formation (P > 0.05).

Conclusions:

MTA Fillapex has a similar dentinal wall adaptation ability as AH Plus does.

Comparison of Microleakage of MTA and CEM Cement Apical Plugs in Three Different Media

Introduction:

Microleakage is of the causes of endodontic treatment failure. The aim of this in vitro study, was to compare the microleakage of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement apical plugs in three environments.

Methods and Materials:

A total of 130 human extracted single rooted teeth were collected. After decoronation, preparation of the root canal space and simulation of open apices, 5 teeth were selected as positive and negative control groups and the rest of the samples were randomly divided into two groups (MTA plug and CEM cement plug) and each group was divided into 3 subgroups (dry, contaminated with saliva and contaminated with blood). In each group apical plug was placed into the canal. After full setting of the apical plug, microleakage of the samples were evaluated using fluid filtration method and the data were analyzed using two-way analysis of variance.

Results:

In dry and saliva contaminated environments, the leakage of MTA samples were 40.906±2.081 and 39.608±2.081, respectively which was significantly more than that of CEM cement samples (26.977±2.081 and 27.000±2.081, respectively). However, in blood-contaminated environments, the amount of leakage in MTA group (21.640±2.081) was significantly lower than CEM cement group (44.358±2.081).

Conclusion:

According to the results of this study, in dry and saliva-contaminated conditions CEM cement provides significantly better seal in comparison to MTA

Bacterial leakage in root canals filled with AH Plus and dentine bonding agents

OBJECTIVE

The aim of this study was to compare the efficacy of different dentine adhesives in delaying the coronal bacterial leakage of Enterococcus faecalis in filled root canals. Materials and methods. Ninety-five lower incisors of patients >65 years of age were instrumented using the ProTaper system and were irrigated with 1 mL of 2.5% sodium hypochlorite (NaOCl) alternated with 1 mL 17% EDTA between each file change. Final irrigation was performed with 5 mL of 17% EDTA and then flushed with 5 mL of distilled water. The teeth were randomly divided into five experimental groups (n = 15/group) and one of the following dentine adhesives was applied: (1) AdheSE; (2) Excite DSC; (3) Clearfil Protect Bond; (4) One Coat 7.0; or (5) Control group without adhesive. After filling the root canals, the samples were mounted on a double chamber device to evaluate the bacterial filtration of E. faecalis during a period of 240 days. The results underwent non-parametric Kaplan-Meier survival analysis and comparisons among groups were done using the Log-Rank test.

RESULTS

At 240 days, E. faecalis was detected in samples of all groups in the lower chamber. The highest survival value was obtained by One Coat 7.0, giving statistically significant differences from the other groups, whereas Clearfil Protect Bond, AdheSE and Excite DSC showed similar behaviours, likewise similar to the Control group.

CONCLUSIONS

One Coat 7.0 adhesive system provides the longest survival value to delay E. faecalis coronal leakage in filled root canals.

The Effect of Root Canal Irrigation with Combination of Sodium Hypo-chlorite and Chlorhexidine Gluconate on the Sealing Ability of Obturation Materials

Objectives:

The aim of this study was to evaluate the effect of the precipitate that was formed by combining Sodium Hypochlorite (NaOCl) and Chlorhexidine Gluconate (CHX) on the sealing ability of root canal obturation materials.

Materials and Methods:

The fluid filtration method was conducted on a total of 100 roots. Samples were randomly divided into two control (n=5) and three experimental groups (n=30). The samples in group 1 were irrigated with 1.5 mL of 2.5% NaOCl, and then the smear layers of the teeth were removed by 17% EDTA, while the specimens of group 2 were irrigated by 1.5 mL of 2.5% NaOCl and 1.5 mL of 2% CHX; after the smear layer removal, a final flush with 1.5 mL of 2.5% NaOCl was performed. The samples of group 3 were irrigated the same as group 1 but after the smear layer removal canals were irrigated again with 1.5 mL of 2.5% NaOCl and then a final flush with 1.5 mL of 2% CHX was performed. Teeth were obturated with gutta-percha and AH26 sealer and after seven days, microleakage was evaluated by the fluid filtration technique. The results were analyzed by the ANOVA and Tukey's test.

Results:

The samples in group 3 had significantly greater microleakage compared to teeth in group 1, 2 (p<0.05), and the specimens in group 1 showed significantly less amount of microleakage than samples in group 2, 3 (p<0.05).

Conclusion:

The presence of the precipitate that is formed due to interaction between NaOCl and CHX has negative effect on the sealing ability of gutta-percha and AH26 sealer.

Evaluation of Apical Micro-leakage of Different Endodontic Sealers in the Presence and Absence of Moisture

Background and aims. With availability of hydrophilic sealers, drying of the canals before endodontic obturation is still a matter of debate. The aim of this study was to compare the apical micro-leakage of AH26, Excite DSC, MTA Fillapex, and ZOE sealers in dry and moist root canals.

Materials and methods. This experimental study was performed on 90 extracted maxillary central incisors. Rotary files were used for preparation of the canals. Root canals were filled with a single gutta percha cone, using one of the four sealers, under dry and moist root canal conditions (10 teeth in each group). Orifices were sealed with glue wax and all root surfaces were covered with nail polish except the positive control group. After ten days in 100% humidity, teeth were placed in methylene blue, and then were cut in longitudinal axis. Blue color permeability was measured by stereomicroscope in micrometers. Data were analyzed by t-test, ANOVA and Scheffe post hoc test using SPSS V.18 software at P < 0.05.

Results. Mean apical micro-leakage was significantly lower in the dry groups (P < 0.001). Minimum and maximum micro-leakage was seen in AH26 and ZOE, respectively. MTA Fillapex did not exhibit a significant difference in apical micro-leakage between dry and moist conditions (P > 0.05). Apical micro-leakage was significantly higher in the Excite DSC groups (P < 0.001).

Conclusion. AH26 provided the least apical micro-leakage under dry conditions while ZOE had the highest micro-leakage under moist conditions. MTA Fillapex provided acceptable apical seal regardless of moisture.

Use of fluid filtration method to evaluate the effect of master cone size on the apical seal of severely curved root canals

The apical third of most root canals shows some degree of curvature, which is important in cleaning/shaping and obturation during root canal treatment. The present study evaluated the effect of master cone size on the apical seal of severely curved root canals. Thirty-eight mesial roots of human mandibular first molars were prepared using the crown-down technique. All samples were mature roots with closed apices, had no carious lesions or resorption, and had a canal curvature of > 45º to 60º. Two samples were used as a negative and positive control to evaluate the fluid filtration equipment, and the remaining 36 samples were equally divided into groups A, B, and C based on master cone size, namely, gutta-percha #20, #25, and #30, respectively. The fluid filtration method was used to evaluate microleakage. No significant difference in microleakage was observed among groups (P = 0.31). In conclusion, an increase in master cone size up to #30 does not significantly influence apical microleakage.

Zinc oxide nano-particles as sealer in endodontics and its sealing ability

Aims:

The aim of this study was to evaluate the sealing ability of new experimental nano-ZOE-based sealer.

Settings and Design:

Three types of nano-ZOE-based sealer (calcined at different temperatures of 500, 600 and 700°C) with two other commercially available sealers (AH26 and micro-sized zinc oxide eugenol sealer) were used.

Materials and Methods:

Zinc oxide nano-particles were synthesized by a modified sol-gel method. The structure and morphology of the prepared powders were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The instrumented canals of 60 single-rooted teeth were divided into five groups (n = 10), with the remaining ten used as controls. The canals were filled with gutta-percha using one of the materials mentioned above as sealer. After 3, 45 and 90 days, the samples were connected to a fluid filtration system.

Statistical Analysis Used:

The data were analyzed using Student's t-test.

Results:

The XRD patterns and TEM images revealed that all the synthesized powders had hexagonal wurtzite structures with an average particle size of about 30-60 nm at different calcination temperatures. Microleakage in AH26 groups was significantly more than that in three groups of ZnO nano-particles at all the three evaluation intervals. Apical microleakage of ZnO micro-powders was significantly more than that of all the materials, but the sealing ability of ZnO nano-powder sealers did not differ significantly.

Conclusion:

The results of this study showed that the synthesized ZnO nano-powder sealers are suitable for use as a nano-sealer in root canal therapy to prevent leakage; however, further studies should be carried out to verify their safety.

Rapid kill-novel endodontic sealer and Enterococcus faecalis

With growing concern over bacterial resistance, the identification of new antimicrobial means is paramount. In the oral cavity microorganisms are essential to the development of periradicular diseases and are the major causative factors associated with endodontic treatment failure. As quaternary ammonium compounds have the ability to kill a wide array of bacteria through electrostatic interactions with multiple anionic targets on the bacterial surface, it is likely that they can overcome bacterial resistance. Melding these ideas, we investigated the potency of a novel endodontic sealer in limiting Enterococcus faecalis growth. We used a polyethyleneimine scaffold to synthesize nano-sized particles, optimized for incorporation into an epoxy-based endodontic sealer. The novel endodontic sealer was tested for its antimicrobial efficacy and evaluated for biocompatibility and physical eligibility. Our results show that the novel sealer foundation affixes the nanoparticles, achieving surface bactericidal properties, but at the same time impeding nanoparticle penetration into eukaryotic cells and thereby mitigating a possible toxic effect. Moreover, adequate physical properties are maintained. The nanosized quaternary amine particles interact within minutes with bacteria, triggering cell death across wide pH values. Throughout this study we demonstrate a new antibacterial perspective for endodontic sealers; a novel antibacterial, effective and safe antimicrobial means.

Towards antibacterial endodontic sealers using quaternary ammonium nanoparticles

AIM

To change and characterize the antibacterial properties of endodontic sealers by incorporating low concentrations of insoluble antibacterial nanoparticles (IABN).

METHODOLOGY

The antibacterial effect against Enterococcus faecalis was evaluated by (i) agar diffusion test (ADT), (ii) direct contact test (DCT) and (iii) scanning electron microscopy (SEM). IABN were incorporated into AH Plus (Dentsply, DeTrey Konstanz, Germany) and GuttaFlow (Coltène Whaledent, Langenau, Germany) at concentrations of 0.5%, 1% or 2% weight/weight. Bacterial growth rates were analysed using ANOVA followed by Tukey's test.

RESULTS

The antibacterial tests demonstrated total bacterial growth inhibition using AH Plus samples incorporating 2% weight/weight IABN after 4 weeks (P < 0.005). DCT showed total growth inhibition of up to 6 logs in viable count in AH Plus samples incorporating IABN and up to 4 log in count in GuttaFlow incorporating IABN (P < 0.005). Significant differences were found between the unmodified sealers and the experimental groups. No antibacterial effect was observed in the ADT, indicating IABN were not diffusing into the agar. Furthermore, SEM indicated bacterial cell wall damage and lysis.

CONCLUSIONS

AH Plus and GuttaFlow incorporating low concentrations of IABN exhibited significant and stable antimicrobial properties.

Evaluation of the sealing ability of resin cement used as a root canal sealer: An in vitro study

AIM

This study was designed to evaluate the apical seal of root canals obturated with resin cement as a root canal sealer and compare with that of the glass ionomer and zinc oxide eugenol sealers using a cold lateral condensation gutta-percha technique.

BACKGROUND

Successful root canal treatment requires three-dimensional obturation of the root canal system with nonirritating biomaterials. None of the available materials are capable of providing a fluid tight seal.

MATERIALS AND METHODS

The prepared teeth were randomly divided into three groups of 15 each to be obturated using three different sealers. Group I: zinc oxide eugenol (Tubliseal), Group II: Glass ionomer (Ketac Endo), and Group III: resin cement (C & B Superbond). All the specimens were stored in 100% relative humidity at 37° for 24 h. The specimens were placed in 2% methylene blue dye for 48 h and sectioned. The dye penetration was evaluated under a stereomicroscope.

RESULTS

The "Kruskal" Wallis test was carried out to test the equality of mean. All the specimens showed dye leakage, and there was a statistically significant difference (P < 0.0001) among the groups. The specimens in Group III showed a minimal leakage and the specimens in Group I showed a maximum leakage.

CONCLUSION

Resin cement sealed the root canals significantly better when compared with zinc oxide eugenol and glass ionomer sealers.