Push-out strength of methacrylate resin-based sealers to root canal walls

An In Vitro Comparative Study of the Push-out Bond Strengths of Various Endodontic Sealers to Radicular Dentin

BACKGROUND

The bond strength of an endodontic sealer to the root dentin is an important factor in maintaining the integrity of the root canal seal. The present study aimed to assess the push-out bond strength of three endodontic sealers used with the single-cone obturation technique.

MATERIALS AND METHODS

The root canals of 40 central maxillary incisors were instrumented using ProTaper Universal NiTi rotary files. The roots were divided into 4 groups (N = 10) according to the type of root canal sealers: Group 1 (control group): AH Plus/Gutta-percha lateral condensation technique (LC); Group 2: AH Plus/Gutta-percha single-cone technique (SC); Group 3: GuttaFlow 2/SC; Group 4: Realseal SE/SC. After obturation, each tooth was prepared for push-out assessment. The total and sectional push-out bond strengths were measured and statistically analysed. Furthermore, failure modes were identified microscopically.

RESULTS

The results indicated that samples in the first group showed the highest total and sectional bond strengths. Samples from other groups showed statistically similar total bond strengths. The highest sectional bond strength was found mainly in the apical root sections. Cohesive failure was predominant for the first group, whereas adhesive failure was predominant in the other groups.

CONCLUSIONS

It could be concluded that the dentin bond strengths of the tested sealers used with the single-cone technique were nearly similar but lower than those of AH Plus/LC. The highest sectional bond strength was observed in the apical thirds. The failure mode was mostly cohesive for AH Plus/LC and adhesive for sealers used with the single-cone obturation technique.

Does Caffeic Acid Phenethyl Ester as an Irrigation Solution Increase the Adhesive Quality of Root Canal Sealer?

Aim:

To evaluate the effect of the caffeic acid phenethyl ester (CAPE) as a root canal irrigation agent on the push-out bond strength of the AH-Plus sealer.

Materials and Methods:

A total of 75 single-rooted teeth were decoronated and were randomly divided into 5 groups of 15 roots for irrigation protocols: Group NaOCl: 5.25 percent NaOCl; Group CAPE: 0.5 percent CAPE; Group NaOCl + ethylenediaminetetraacetic acid (EDTA): 5.25 percent NaOCl-17 percent EDTA; Group NaOCl + CAPE: 5.25 percent NaOCl-0.5 percent CAPE; and Group CAPE + EDTA: 0.5 percent CAPE-17 percent EDTA (for 3 min each group). All root canals were then obturated and 1-mm-thick horizontal slices were obtained from different root thirds of the root canal (coronal, middle, and apical, respectively). The groups were challenged with push-out tests. Modes of failure were determined under a stereomicroscope.

Results:

The CAPE-EDTA-treated group presented the highest mean bond strength in the coronal region of root dentin ( P < .05). The CAPE-treated group had a higher mean bond strength than the NaOCl-treated group ( P < .05). The mixed mode of failure was most predominant in all groups.

Conclusion:

Under the presented in vitro conditions, CAPE alone or in combination with EDTA or NaOCl demonstrated a positive effect that increased the push-out bond strength of the AH-Plus sealer to root dentin.

An In vitro Comparison of Pushout Bond Strength of Resilon with MetaSEAL and AH Plus Sealers

Aim

The aim of this study is to evaluate and compare the pushout bond strengths of Resilon with two different sealers: Resilon/MetaSEAL (methacrylate based) and Resilon/AH Plus (an epoxy resin-based sealer).

Materials and Methods

Forty single canal anterior teeth were decoronated at cementoenamel junction and standardized to 10 ± 1 mm length. Working length was determined followed by biomechanical preparation. Then, the specimens were randomly assigned into two groups of 20 teeth each based on the sealer used with Resilon. All canals were obturated using single-cone obturation technique. Root samples were prepared for pushout testing. The universal testing machine gave the debonding force for individual specimen. This was done for all the specimens.

Statistical Analysis

This was done by using unpaired Student's t-test.

Results

The roots filled with Resilon/MetaSEAL had higher bond strength (1.49 ± 0.09 MPa) compared to Resilon/AH Plus (0.90 ± 0.04 MPa) group. The difference in bond strength was statistically significant (P = 0.0000).

Conclusion

Through this pushout bond strength test, it could be noted that MetaSEAL did appear to bond to the dentin and could be used as a potential endodontic sealer.

Comparison of the effect of MTAD and conventional irrigation agents on apical leakage and push-out bond strength of root canal filling

The aim of this study was to evaluate the effect of MTAD (a mixture of tetracycline isomer, an acid, and a detergent) and conventional irrigation agents on the apical leakage and push-out bond strength of root canal filling and to correlate the apical leakage and push-out bond strength. Root canals of 120 maxillary central incisors were prepared with a ProTaper file up to F3 and distributed to six groups. Saline, 1% NaOCl, 17% EDTA, 17% EDTA/1% NaOCl, and 2% chlorhexidine (CHX) solutions were used between each file change, and 5 mL of the same irrigating solution was used for the final flush. In the MTAD group, the root canals were irrigated with 1.3% NaOCl between each file and 5 mL of MTAD for the final flush. All the root canals were filled with AH Plus sealer and gutta-percha cones. Apical leakage was evaluated using a fluid transport system. After the apical leakage test, each tooth was prepared for the push-out assessment. The statistical analysis revealed that the irrigation solutions had no effect on the apical leakage of the root canal fillings (p = 0.258). The root fillings of the groups irrigated with MTAD showed significantly lower push-out bond strength values than the other groups (p < 0.001). These commonly used irrigating solutions did not affect the apical leakage of the root canal sealer. MTAD reduced the bond strength of the root canal sealer to the root canal dentin.

Evaluation of the resin cement thicknesses and push-out bond strengths of circular and oval fiber posts in oval-shapes canals

PURPOSE

The aim of this study was to evaluate whether the push-out bond strength varies between oval and circular fiber posts, and to examine the effect on the resin cement thicknesses around the posts.

MATERIALS AND METHODS

Eighteen mandibular premolar roots were separated into two groups for oval and circular fiber posts systems. Post spaces were prepared and fiber posts were luted to the post spaces. Roots were cut horizontally to produce 1-mm-thick specimens. Resin cement thicknesses were determined with a metallographic optical microscope and push-out tests were done.

RESULTS

No significant differences were observed in terms of push-out bond strength between the oval and circular fiber posts (P>.05) The resin cement thicknesses of the oval posts were greater than those of the circular posts group in the coronal, middle and apical specimens (P<.05).

CONCLUSION

In the light of these results, it can be stated that resin cement thickness does not affect the push-out bond strength.

Development of an antibacterial root canal filling system containing MDPB

An antibacterial monomer 12-methacryloyloxydodecylpyridinum bromide (MDPB)-containing experimental, chemically cured primer was prepared to develop a new resin-based root canal filling system. This study investigated the antibacterial effects of the MDPB-containing primer (experimental primer [EP]) against Enterococcus faecalis and assessed the in vitro bonding and sealing abilities of the filling system, consisting of EP and a Bis-GMA-based sealer resin. Antibacterial effects of EP were evaluated by contact with planktonic or adherent bacteria for 30 or 60 sec, and the viable bacterial number was counted. The antibacterial effects against E. faecalis in dentinal tubules were also assessed, according to a root canal infection model. Bonding and sealing abilities of the experimental filling system were examined by microtensile bond strength tests and leakage tests based on fluid filtration methods. Significantly greater reduction in viable bacteria in planktonic and adherent form was obtained by short-period contact with EP compared with the control primer (without MDPB) or with the proprietary (Epiphany) primer (p < .05). Significantly greater bactericidal effects of the EP inside the dentinal tubule of root, as opposed to the control primer or Epiphany primer, were confirmed according to a root canal infection model (p < .05), and 100% killing of E. faecalis could be obtained by the application of EP after irrigation with a 5% sodium hypochlorite solution. The experimental endodontic filling system demonstrated significantly greater bond strength to root dentin than Epiphany sealer system (Epiphany primer and Epiphany Root Canal Sealant; p < .05), showing formation of resin tags and a hybridized layer. Leakage tests clarified that the experimental system provided excellent sealing. This study confirmed that the MDPB-containing experimental antibacterial primer has the ability to effectively disinfect the root canal. Additionally, the experimental root canal filling system employing this primer and the Bis-GMA-based sealer resin is useful for achieving good sealing, suggesting its possible benefit for successful endodontic treatments.

Adhesive interface and bond strength of endodontic sealers to root canal dentine after immersion in phosphate-buffered saline

This study evaluated the bond strength (BS) and the adhesive interface of four endodontic sealers to root canal dentine, before, and after immersion in phosphate buffered saline (PBS) to simulate an in vivo environment. Eighty roots were instrumented using ProTaper rotatory files, under irrigation with 17% EDTA and 1% NaOCl. Posteriorly were divided into four groups (n = 20) according to the sealer used: Endofill, AH Plus, Sealapex, and MTA Fillapex. Each group was divided into two subgroups (n = 10) and stored at 37°C immersed in water for 7 days and in PBS for 60 days. From each subgroup, 1 mm thick sections were obtained. One section of each region (coronal, middle, and apical) was submitted to the push-out test and failures were observed. Twelve sections of each subgroup (four from each region) were evaluated under SEM. Three-way ANOVA evaluation for BS showed significant differences between groups and regions (P < 0.0001), but not between subgroups (P > 0.05). AH Plus had significantly higher BS than the others sealers, regardless of the analyzed subgroup (Tukey's test, P < 0.5). The most common failures were adhesive to dentine and cohesive of the sealer. The SEM evaluation (Kruskal-Wallis, Mann-Whitney) showed homogeneous adhesive interface formed and sealer tags in all groups with significant statistical differences with AH Plus, regardless of PBS immersion. AH Plus was superior to the other sealers for both BS and quality of interface formation. Immersion in PBS did not interfere on BS or adhesive interface of the sealers tested.

Push-out bond strength of self-adhesive methacrylate resin-based sealers to root dentin

This study examined the adhesive strength of two self-adhesive methacrylate resin-based sealers (MetaSEAL and RealSeal SE) to root dentin and compared them with RealSeal and AH Plus in properties. A total of 48 extracted human single-rooted teeth were used to prepare the 0.9-mm thick longitudinal tooth slice (each per tooth). Standardized simulated canal spaces of uniform dimensions were prepared in the middle of radicular dentin. After treated with 5.25% sodium hypochlorite (NaOCl) and 17% EDTA, tooth slices were allocated randomly to four groups (n=12) in terms of different sealers used: MetaSEAL, RealSeal SE, RealSeal, and AH plus groups. The simulated canal spaces were obturated with different sealers in each group. There were 10 slabs with 20 simulated canal spaces (n=20) used in each group for push-out testing. The failure modes and the ultrastructures of fractured sealer-dentin interfaces were examined. The remaining 2 slabs in each group underwent partial demineralization for observation of the ultrastructure of resin tags. The results showed that the push-out bond strength was 12.01±4.66 MPa in MetaSEAL group, significantly higher than that in the other three groups (P<0.05). Moreover, no statistically significant differences were noted in the push-out bond strength between RealSeal SE (5.43±3.68 MPa) and AH Plus (7.34±2.83 MPa) groups and between RealSeal SE and RealSeal (2.93±1.76 MPa) groups (P>0.05). Mixed failures were predominant in the fractured sealer-dentin interfaces in MetaSEAL and AH Plus groups, while adhesive failures were frequently seen in RealSeal SE and RealSeal groups. In conclusion, after complete removal of the smear layer, MetaSEAL showed superior bond ability to root dentin. The RealSeal SE is applicable in clinical practice, with its adhesive strength similar to that of AH Plus. The self-adhesive methacrylate resin-based sealer holds promise for use in endodontic treatment.

Comparison of two techniques for selection of master gutta-percha cone using micro-computed tomography

This study used micro-computed tomography (micro-CT) to evaluate the fit of the master gutta-percha cone at time of cone fit, gutta-percha volume in the filling material, and the filling material volume in relation to the canal at the apical limit of the working length. Root canals of 20 maxillary central incisors were prepared with rotary instruments and distributed into two groups (n=10). The gutta-percha cone tip was either plasticized (apical thermal impression technique - ATI) or not (conventional technique - CT), and its apical fit was checked. The apical 1 mm of working length was examined with a micro-CT, canals were filled with gutta-percha and sealer, and new micro-CT scans were obtained. In CT, gutta-percha filled 35.83 ± 15.05% of the canal at cone selection and 38.72 ± 11.64% after filling. In ATI, these values were 23.14 ± 7.74% and 26.98 ± 20.40%, respectively. Gutta-percha volume in the filling material, and filling material volume in relation to the canal were, respectively, 61.28 ± 11.64% and 87.76 ± 9.98% for CT, and 73.00 ± 20.41% and 89.96 ± 9.08% for ATI. No significant difference was found between cone selection and after canal filling, for either CT (p=0.593) or ATI (p=0.4975). The techniques did not differ significantly with respect to gutta-percha volume in the filling material (p=0.132) and filling material volume in relation to the canal (p=0.612). An ideal fit of the master gutta-percha cone at working length was not achieved regardless of the cone selection technique, and the material-filled area was similar for both techniques.

Resilon: a comprehensive literature review

Background and aims. An ideal root canal filling material should completely seal the entire root canal space and block communication between the root canal system and its surrounding tissues; it should also be nontoxic, noncarcinogenic, non-genotoxic, biocompatible, insoluble in tissue fluids and dimensionally stable. Bonding to dentin is a promising property, which can prevent leakage and improve the sealing ability of root canal filling materials. Resilon was developed and rec-ommended initially because the existing rootcanal filling materials did not bond to root canal dentin. Since its introduction in 2004, numerous reports have been published regarding various aspects of this material. The aim of this literature review is to present investigations regarding Resilon's physical and chemical properties and leakage studies. Materials and methods. A review of the literature was performed by using electronic and hand searching methods for Resilon from May 2004 to April 2012. Results. There are many published reports regarding Resilon. The searchshowed that Resilon is composed of a parent polymer, polycaprolactone or Tone, which is a biodegradable aliphatic polyester, with filler particles consisting of bioactive glass, bismuth oxychloride and barium sulfate. It possesses some antibacterial and antifungal properties. It is a promising material for root canal filling. Despite the presence of numerous case reports and case series regarding these applications, there are few designed research studies on clinical applications of this material. Resilon has some drawbacks such as high cost. Conclusion. Resilon seals well and is a biocompatible material. However, more clinical studies are needed to confirm its efficacy compared with other materials.

An ex vivo comparison of the push-out bond strength of a new endodontic filling system (Smartseal) and various gutta-percha filling techniques

The purpose of this study was to evaluate, ex vivo, the push-out bond strength of a new filling material (Smartseal) compared with gutta-percha/AH-26. A total of 40 extracted single-rooted human teeth were used. After instrumentation using the ProTaper rotary system, the root canals were filled as follows: Group 1, Smartseal sealer and a 0.06 taper Smartpoint calibrated to apical tip size 30; Group 2, Smartseal sealer and an F3 SmartpointPT; Group 3, AH-26 sealer and a single F3 ProTaper gutta-percha cone and Group 4, AH-26 sealer and gutta-percha using the cold lateral condensation technique. Two successive disk shaped slices were cut from each root sample and the bond strength was measured using the push-out test. Two-way analysis of variance was used for data analysis with the level of significance set at 0.05. Statistical analysis revealed no significant differences (p > 0.05) between the mean bond strengths of the various groups; thus indicating there was no difference in adhesion to dentine between the Smartseal system and gutta-percha/AH-26 applied using either the single cone or lateral condensation technique.

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.

Persistence of endodontic methacrylate-based cement residues on dentin adhesive surface treated with different chemical removal protocols

The aim of this study was to evaluate the persistence of methacrylate-based cement residues on the dentin, after dentin surface cleaning with ethanol or acetone, with or without previous application of a dentin adhesive. Forty bovine crown fragments were obtained and the dentin surface was washed with 1.0 mL of 2.5% sodium hypochlorite (NaOCl), followed by 0.1 mL of 17% ethylenediaminetetraacetic acid application for 3 min, and final irrigation with 2.5% NaOCl. The specimens were air dried and resin-based cement was rubbed onto the dentine surface with a microbrush applicator. In 20 specimens, previously to cement, a dentin adhesive was applied in all surfaces. After 15 min, the surface was scrubbed with a cotton pellet and moistened with ethanol or acetone, compounding the following groups: G1-99.5% ethanol and G2-acetone, without previous use of dentin adhesive; G3-99.5% ethanol and G4-acetone, with previous use of dentin adhesive. The dentin surface was scrubbed until the cement residues could not be visually detected. Sections were then processed for scanning electron microscopy and evaluated at 500× magnification and scores were attributed to each image according to the area covered by residual sealer, and data were subjected to Kruskal-Wallis at 5% significance. The lower residue presence was observed in G3 (P = 0.005). All surface presented cement residues when acetone was used as cleaning solution (P = 0.0005). The cleaning solutions were unable to completely remove the cement residues from both surfaces. The ethanol used after previous application of the dentin adhesive promoted the lower presence of residues.

Push-out strength of root fillings with or without thermomechanical compaction

AIM

To evaluate the influence of thermomechanical compaction (Tagger's hybrid technique - THT) on the push-out strength of several root filling materials to root dentine.

METHODOLOGY

Root canals of eighty roots in human canines were prepared with the ProTaper system and filled with one of the following materials, using either lateral compaction (LC) (n = 40) or THT (n = 40): AH Plus/gutta-percha (GP) (n = 10), Sealer 26/GP (n = 10), Epiphany SE/Resilon (n = 10) and Epiphany SE/GP (n = 10). Three 2-mm-thick dentine slices were obtained from each third of each root. The root filling in the first slice was subjected to a push-out test to evaluate the bond strength of the materials to intraradicular dentine. Data (in MPa) were analysed using anova and post hoc Tukey's test (P < 0.05). Failure mode was determined at × 25 magnification. The other two slices were prepared for scanning electron microscopy (SEM) to examine the surface of the filling materials.

RESULTS

Lateral compaction (1.34 ± 1.14 MPa) was associated with a significantly higher bond strength (P < 0.05) than the THT (0.97 ± 0.88 MPa). AH Plus/GP (2.23 ± 0.83 MPa) and Sealer 26/GP (1.86 ± 0.50 MPa) had significantly higher bond strengths than the other materials and differed significantly from each other (P < 0.05). There was a significant difference (P < 0.05) between the coronal (1.36 ± 1.15 MPa), middle (1.14 ± 1.05 MPa) and apical thirds (0.95 ± 0.83 MPa). Considering the technique and root filling material interaction, AH Plus/GP-LC was associated with the highest mean values (2.65 ± 0.66 MPa) (P < 0.05). Sealer 26/GP-LC (2.10 ± 0.46 MPa), AH Plus/GP-THT (1.81 ± 0.78 MPa) and Sealer 26/GP-TH (1.63 ± 0.44 MPa) had intermediate values that were not significantly different from each other (P > 0.05). Epiphany SE was associated with the lowest mean values (3.70 ± 0.86 MPa) (P < 0.05), regardless of the root filling technique and type of solid material (cone). Adhesive failures predominated in the specimens filled with Epiphany SE, whilst mixed and cohesive failures were more frequent in those filled with AH Plus and Sealer 26, regardless of the root filling technique. SEM analysis revealed that LC produced a dense and well-compacted filling whilst the use of a hybrid thermomechanical technique resulted in the solid material (GP or Resilon) intermingled within sealer to form a nonhomogenous mass.

CONCLUSION

Lateral compaction was associated with higher bond strengths of the materials to intraradicular dentine than a hybrid technique using thermomechanical compaction. The greatest push-out strengths were obtained when the canals were filled with LC of AH Plus and GP cones.

Resistance to vertical root fracture of endodontically treated teeth with MetaSEAL

INTRODUCTION

The purpose of this in vitro study was to assess the influence of MetaSEAL and AH Plus on the resistance to vertical root fracture of endodontically treated teeth when either the matched-taper single-cone or lateral condensation technique was used.

METHODS

Ninety extracted single-canal mandibular premolar teeth were sectioned, leaving a standard root length of 13 mm. The buccolingual and mesiodistal diameters were measured, and the teeth were randomly divided into 6 groups (n = 15). There were no statistically significant differences between the groups in terms of the diameters. In group 1, no instrumentation or obturation was performed. The rest of the roots were chemomechanically prepared with nickel-titanium ProTaper rotary instruments up to size F3 at the working length. Group 2 was left unobturated. Groups 3 and 4 were obturated with AH Plus used with the matched-taper single-cone and lateral condensation techniques, respectively. In groups 5 and 6, MetaSEAL was used instead of AH Plus. All of the roots were mounted vertically in self-curing acrylic resin blocks that exposed 8 mm of the coronal part. Then the roots were subjected to a vertical loading force (1 mm/min). The force required to produce a fracture was recorded in newtons. The data were analyzed by using Kruskal-Wallis and post hoc Dunn multiple comparison tests (P < .05).

RESULTS

Although we did not detect statistical significance, there was a substantial difference between the fracture resistance values of the intact and instrumented but not obturated roots. The groups in which AH Plus and MetaSEAL were used with the matched-taper single-cone technique showed significantly higher fracture resistance values than the instrumented but not obturated roots (P < .05). There were no significant differences between the groups submitted to the matched-taper single-cone technique. The force required to fracture the roots in the group treated with AH Plus and the lateral condensation technique was similar to that required to fracture intact roots, whereas the group treated with MetaSEAL and the lateral condensation technique revealed comparable values to the instrumented but not obturated roots.

CONCLUSIONS

When used with the matched-taper single-cone technique, MetaSEAL and AH Plus have the potential to reinforce endodontically treated teeth.

Push-out bond strength of two new calcium silicate-based endodontic sealers to root canal dentine

AIM

To assess the push-out bond strength of two new calcium silicate-based endodontic sealers in the root canals of extracted teeth.

METHODOLOGY

Thirty extracted single-rooted central incisors of similar sizes were selected randomly and distributed to three groups (n = 10). All canals were instrumented using ProTaper rotary instruments to achieve tapered canal walls. Irrigation was performed using 5 mL 2.5% NaOCl between each instrument, and the smear layer was removed using 5 mL 17% EDTA. The canals were filled with three different sealers using a cold lateral compaction technique: group 1: AH Plus + gutta-percha, group 2: I Root SP + gutta-percha and group 3: MTA Fillapex + gutta-percha. Three horizontal sections were prepared at a thickness of 1 mm ± 0.1 in the apical, middle and coronal parts of each root. The test specimens were subjected to the push-out test method using a Universal Test Machine (Instron, Canton, MA, USA) that carried 1-mm, 0.5-mm and 0.3-mm plungers for coronal, middle and apical specimens, respectively. The loading speed was 1 mm min(-1) . The push-out data were analysed by two-way analysis of variance (anova) and the post hoc Holm-Sidak test, with significance set at P < 0.05.

RESULTS

In the coronal specimens, there was no significant difference between the sealers. In the middle and apical segments, there was no significant difference between I Root SP and AH Plus groups. However, the I Root SP and AH Plus had significantly higher bond strength values than the MTA Fillapex (P < 0.05). In terms of root segments, the bond strengths in the middle specimens and the apical specimens were higher compared with the bond strengths in the coronal specimens (P < 0.05). There were no significant differences between the bond strengths in the middle and apical specimens.

CONCLUSION

MTA Fillapex had the lowest push-out bond values to root dentine compared with other sealers.