The shear bond strength of glass ionomer cement sealers to bovine dentine conditioned with common endodontic irrigants

The efficiency of different irrigation activation techniques in the removal of calcium silicate-based endodontic sealer from artificially created groove

This study evaluated the removal of a calcium silicate-based sealer (EndoSeal MTA) with needle irrigation (NI), passive ultrasonic irrigation (PUI), XP-endo Finisher (XPF) and EDDY. A total of 56 human mandibular premolars were instrumented up to size 40.04 taper. The roots were separated longitudinally, and grooves were prepared with an ultrasonic tip at one-half of each root canal. The grooves were covered with EndoSeal MTA and re-attached roots were investigated based on the activation techniques applied. The results showed that significantly more material (p < 0.05) was removed in the EDDY group compared to the NI, PUI and XPF groups in the apical region. In the coronal region, no significant difference was observed between EDDY, XPF and PUI (p > 0.05), whereas all the latter were significantly more effective than NI (p < 0.05). These findings show that the removal of EndoSeal MTA can be more effective with EDDY compared to XPF, PUI and NI in the apical region.

Efficacy of different irrigation agitation systems in the removal of root canal sealers from artificial standardised grooves

The present study aims to assess the efficacy of different irrigation agitation systems in removing calcium silicate-based sealers from artificial standardised apical grooves. After the root canal instrumentation of 96 teeth, artificial apical grooves were created in half of each root. The samples were divided into two main groups according to the sealer type (AH Plus Jet [APJ] and Sure-Seal Root™ [SSR]) (n = 48). The root halves were then reassembled and divided into four experimental groups based on the final irrigation technique used: Conventional Syringe Irrigation (CSI), Ultrasonic Irrigant Agitation (UIA), Sonic Agitation (SA) and Manual Dynamic Agitation (MDA). The roots were then dissembled to assess the amount of root canal sealer. UIA significantly removed more of SSR sealer than CSI, MDA and SA while there was no statistical difference between CSI, MDA, SA and UIA groups in the APJ group. None of the irrigation agitation systems used had completely removed the APJ and SSR sealers. However, UIA was more effective in removing SSR sealer from the standardised apical groove than were CSI, MDA and SA.

Push-Out Bond Strength and SEM Evaluation in Roots Filled with Two Different Techniques Using New and Conventional Sealers

The aim of this study was to evaluate the influence of calcium-silicate-based sealer (Endosequence-BC-Sealer) in roots, filled with thermo-plasticized injectable technique aided by Calamus-Flow-Delivery-System, on bond strength to radicular dentin, in comparison with conventional epoxy-resin-based sealer (AH-Plus) along with cold-lateral-compaction technique. Root canals of mandibular-premolar teeth (n = 80) were instrumented using Protaper Universal rotary files and were randomly divided into four experimental groups (n = 20) as follows: (1) AH-Plus + cold-lateral-compaction technique; (2) Endosequence-BC-Sealer + cold-lateral-compaction technique; (3) AH-Plus + thermo-plasticized injectable technique; and (4) Endosequence-BC-Sealer + thermo-plasticized injectable technique. Horizontal disc shaped samples from each group (n = 60/group) were obtained and push-out bond strength testing was performed at a cross-head speed of 0.5 mm/min. Data were analyzed statistically using nonparametric Kruskal-Wallis analysis and Mann-Whitney test (p < 0.001). The statistical analysis revealed a significant difference amongst the groups (p < 0.001). The highest bond strength values were found in group 1 compared with all the other experimental groups (p < 0.001), whereas the lowest bond strength values were found in group 4 (p < 0.001). It was concluded that thermo-plasticized injectable technique with Calamus-Flow-Delivery-System lowered the bond strengths of the sealers, especially Endosequence-BC-Sealer. Therefore, this technique is not recommended to calcium-silicate-based sealers. Further studies are needed to confirm the findings of this study.

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.

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.

Resistance to fracture of roots obturated with novel canal-filling systems

INTRODUCTION

This study was conducted to evaluate and compare the fracture resistance of roots obturated with various contemporary canal-filling systems.

METHODS

Fifty single-rooted extracted mandibular premolars were decoronated to obtain 13-mm root segments. Ten roots were left unprepared and unfilled (negative control). Forty canals were instrumented using 0.06 taper EndoSequence files (Brassler, Savannah, GA). Roots were divided according to the obturating system into 4 groups (n = 10): group 1: iRoot SP sealer (Innovative Bioceramix, Vancouver, Canada) + ActiV GP cone (Brasseler USA, Savanah, GA), group 2: iRoot SP sealer + gutta-percha (GP), group 3: ActiV GP sealer + ActiV GP cone, and group 4: ActiV GP sealer + GP. All groups were obturated using single-cone technique. The roots within each group were embedded in acrylic molds and subjected to the fracture resistance test in which a compressive loading (0.5 mm/min) was applied until fracture. Data were statistically analyzed (analysis of variance and Tukey post hoc test).

RESULTS

The significantly highest fracture resistance was recorded for both the negative control group (381.4 ± 53.2 N) and group 1 (iRoot SP sealer/ActiV GP cone [372 ± 62.9 N]) with no significant difference between them, whereas the significantly lowest value was reported in group 4 (ActiV GP sealer/GP cone [288.3 ± 30.5 N]).

CONCLUSION

Bioceramic-based sealer (ie, iRoot SP) is a promising sealer in terms of increasing in vitro resistance to the fracture of endodontically treated roots particularly when accompanied with ActiV GP cones.

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.

Bacterial penetration along different root canal filling materials in the presence or absence of smear layer

AIM

To study the effect of the smear layer on the penetration of bacteria along different root canal filling materials and to examine the dentine/sealer and sealer/core material interfaces for the presence of bacteria.

METHODOLOGY

A total of 110 human root segments were instrumented to size 80 under irrigation with 1% sodium hypochlorite. Half of the roots were irrigated with a 5-mL rinse of 17% EDTA. Roots with and without smear layer were filled with gutta-percha (GP) and AH Plus sealer (AH), GP and Apexit sealer (AP), or RealSeal cones and sealer (RS). Following storage in humid conditions at 37 degrees C for 7 days, the specimens were mounted into a bacterial leakage test model for 135 days. Survival analyses were performed to calculate the median time of leakage and log-rank test was used for pairwise comparisons of groups. The level of significance was set at P = 0.05. Selected specimens were longitudinally sectioned and inspected by scanning electron microscopy for the presence of bacteria at the interfaces.

RESULTS

In the presence of the smear layer, RS and AP leaked significantly more slowly than in its absence. In the absence of the smear layer, AH leaked significantly more slowly than RS. SEM results indicated a differential pattern of bacterial penetration among the sealers.

CONCLUSIONS

Removal of the smear layer did not impair bacterial penetration along root canal fillings. A comparison of the sealers revealed no difference except that AH performed better than RS in the absence of the smear layer.

Shear Bond Strength of Three Resin Based Sealers to Dentin With and Without the Smear Layer

Bond strength of root canal sealers to dentin is an important property for the integrity of the sealings of root-canals. The purpose of this study was to test shear bond strength of three endodontic sealers (Diaket, AH Plus and Endo-REZ). The coronal two thirds of ninety extracted human third molars were removed. The smear layer of the exposed dentin surfaces were removed using 17% EDTA followed by 5.25% NaOCl and the teeth were randomly divided into two groups (n = 45). Group 1 was kept as control and in group 2, uniform smear layer was created using waterproof polishing papers. Three-mm long sections of polyethylene tubing were filled with freshly mixed sealer and placed on the dentin surfaces for conducting a shear bond strength test. The data was calculated as MPa and was statistically analyzed using a two way ANOVA, Kruskal-Wallis and Mann-Whitney U tests. A significant difference was found among the bond strength of the sealers, smear layer, and control groups. AH Plus sealer showed the highest bond strength in smear layer removed surfaces (p < 0.05). Pretreatment with EDTA/NaOCl affected bond strength of AH Plus. AH Plus had the highest bond to dentin with or without smear layer.

The use of glass ionomer cements in both conventional and surgical endodontics

The capacity to bond to dental tissues, especially to dentine, their long-term fluoride release and their biocompatibility make glass ionomer cements (GICs) advantageous for use in endodontics, as well as in restorative dentistry. This review provides information on the basic properties of GICs, such as adhesion, antimicrobial effects and biocompatibility, particularly as they relate to use in endodontics. Indications for the use of GICs in endodontics are orthograde root canal sealing, root-end filling, repair of perforations and root resorption defects, treatment of vertical fractures and maintenance of the coronal seal. The paper includes a review on each of these indications. It is concluded that in spite of the critical handling characteristics and the inconclusive findings regarding sealing ability and antimicrobial activity, there is substantial evidence to confirm their satisfactory clinical performance. Both soft tissue and bone compatibility make them suitable for use during endodontic surgery.

Biocompatibility of an experimental glass-ionomer cement sealer in rat mandibular bone

OBJECTIVE

The purpose of this study was to compare an experimental glass-ionomer cement sealer, KT-308, with a conventional zinc oxide-eugenol sealer, Canals, in terms of tissue compatibility and solubility.

STUDY DESIGN

Tissue reactions were examined under light and electron microscopes at 3 and 20 days after the implantation of either freshly mixed KT-308 sealer or Canals sealer into prepared cavities in rat mandibles.

RESULTS

At 3 days after implantation, no inflammatory reaction was seen around KT-308 sealer, which was in direct contact with the bone surface. In contrast, Canals sealer elicited an initially severe inflammation in the surrounding tissue. At 20 days, the majority of KT-308 sealer remained in the bone cavity. Canals sealer was largely absorbed and surrounded by fibrous tissue with many macrophages. An ultrastructural examination also revealed that no intervening tissue was present between the cut bone surface and the glass-ionomer cement sealer and that disintegrated zinc oxide-eugenol particles were engulfed by macrophages.

CONCLUSIONS

KT-308 sealer possesses better tissue compatibility and lower solubility compared with a conventional zinc oxide-eugenol sealer, suggesting its potential for use as a root canal sealant.

In vitro evaluation of the cytocompatibility of a glass-lonomer cement sealer

The purpose of this study was to evaluate the cytocompatibility of two different types of root canal sealers in cell culture. Human periodontal ligament cells were cultured with set materials from an experimental glass-ionomer cement sealer (KT-308) and a commercially available zinc oxide-eugenol-based sealer (Canals) for 1, 3, and 7 days. Cytotoxic effects were evaluated from the morphological changes under a light microscope. Canals induced severe degenerative alteration of human periodontal ligament cells. In contrast, human periodontal ligament cells adjacent to KT-308 showed normal morphology and growth during the culture period. These results suggest that the glass-ionomer cement sealer, KT-308, is cytocompatible and has good potential as a root canal sealer.

Apical leakage of four endodontic sealers

The purpose of this study was to evaluate the sealing properties of four root canal sealers. Forty-eight maxillary central incisors were instrumented with Profile rotary instruments. They were randomly divided into four groups (n = 12) and filled using lateral condensation with one of the four sealers: Sealapex, Pulp Canal Sealer, AH 26, and Ketac-Endo. The apical leakage was measured with a fluid filtration method and expressed as L s(-1) KPa(-1). The teeth filled with Sealapex displayed a higher apical leakage (8.42 +/- 4.2 10(-11) L s(-1) KPa(-1)) than those filled with AH 26 (2.10 +/- 1.39 10(-11) L s(-1) KPa(-1)), Pulp Canal Sealer (0.17 +/- 0.09 10(-11) L s(-1) KPa(-1)) or Ketac-Endo (0.32 +/- 0.24 10(-1) L s(-1) KPa(-1)) (p < 0.01). No statistically significant difference was found among AH 26, Pulp Canal Sealer, and Ketac-Endo. No correlation was found between the sealing efficiency of the four sealers and their adhesive properties recorded in a previous study.

The hemolytic and cytotoxic properties of a zeolite-containing root filling material in vitro

OBJECTIVE

This in vitro study characterized the hemolysis and cytotoxicity of ZUT, an experimental glass ionomer cement (GIC) sealer with an added antimicrobial-containing zeolite (0.2% Zeomic w/w).

STUDY DESIGN

ZUT, Ketac-Cem (GIC component of ZUT), Ketac-Endo, and two AH 26 sealer formulations were tested at various times after mixing. Hemolysis produced by standardized specimens was determined spectrophotometrically (n = 6/material). Cytotoxicity was assessed by using a Millipore Filter test with a HeLa cell monolayer (n = 10/material). Tests were repeated, and results were analyzed with a one-way analysis of variance (alpha = .05).

RESULTS

Disks of AH 26 containing silver produced the most hemolysis of all test groups (P < .0001). Compared to controls, GICs and AH 26 formulations were noncytotoxic at 1 and 6 hours after mixing, respectively (P > .05). Addition of Zeomic did not increase the cytotoxic and hemolytic activity of Ketac-Cem (P > .05).

CONCLUSION

Overall results suggest ZUT is less cytotoxic than AH 26 and possesses characteristics similar to the other GIC formulations tested.

Adhesion of endodontic sealers to dentin and gutta-percha

Adhesion of endodontic sealers to dentin and gutta-percha offers clues into their interaction with the wall of the root canal and the filling material. In this in vitro study, four classes of endodontic sealers (Kerr, a ZOE-based sealer; Sealapex, a calcium hydroxide-based sealer; AH 26, an epoxy resin-based system; and Ketac-Endo, a glass-ionomer based sealer) were compared for their ability to bond to dentin or gutta-percha. Flat coronal dentin or gutta-percha surfaces were created by using a diamond-impregnated saw blade. Aluminum cylinders (ca. 5-mm diameter) were stabilized on the substrates with small amounts of wax and then filled with one of the sealers. After setting in 100% humidity for 24 h, their tensile bond strengths were measured. Controls were the unfilled cylinders stabilized with wax. The bond strengths and modes of failure were measured. The results were statistically analyzed by using a two-way ANOVA (materials versus substrates) and Student-Newman-Keuls test at alpha = 0.05. The results indicated that sealant bond strengths to dentin (from lowest to highest mean +/- SD, n = 10) were: Kerr 0.13 +/- 0.02; Sealapex 0.30 +/- 0.08; Ketac-Endo 0.80 +/- 0.24; AH 26 2.06 +/- 0.53 MPa. The latter two were significantly different (p < 0.05) from the first two sealers and from themselves. The sealant bond strength to gutta-percha (from lowest to highest mean +/- SD, n = 10) were: Ketac-Endo 0.19 +/- 0.01; Sealapex 0.22 +/- 0.01; Kerr 1.07 +/- 0.19; AH 26 2.93 +/- 0.29 MPa. AH 26 gave the significantly highest bonds to gutta-percha.

The effects of dentine pretreatment on the adhesion of root-canal sealers

AIM

The adhesion of five root-canal sealers to dentine and gutta-percha was studied. The effects of various dentine pretreatments on adhesion were also investigated.

METHODOLOGY

Root dentine cylinders, 4 mm in diameter, were prepared from human teeth. The dentine surfaces were conditioned with either 37% H(3)PO(4) for 30 s, 25% citric acid for 30 s, 17% EDTA for 5 min or a rinse with 10 mL distilled water (control). Gutta-percha cylinders, 4 mm in diameter, were prepared and their end surfaces polished flat. The dentine and gutta-percha surfaces were coated with freshly mixed sealer: Grossman's sealer (GS), Apexit (AP), Ketac-Endo (KE), AH Plus (AH), RoekoSeal Automix (RS) or RoekoSeal Automix with an experimental primer (RP). The surfaces were pressed together and the sealers allowed to set. The test specimens were subjected to a tensile force in a universal testing machine.

RESULTS

Mean tensile bond strengths (MPa +/- SD) ranged from 0.07 +/- 0.01 (AP) to 1.19 +/- 0.47 (AH). Pretreatment with EDTA showed no effect or produced weaker bonds than controls. Phosphoric and citric acid pretreatments increased adhesion of GS. A primer used with RoekoSeal significantly enhanced its adhesion to untreated dentine. Inspection of fractured surfaces indicated failure of adhesion to dentine for GS and RS and to gutta-percha for KE and RP. The failure appeared to be mainly cohesive within the sealer for AH and AP.

CONCLUSIONS

Removal of the smear layer may impair sealer adhesion to dentine. Different sealer types require different dentine pretreatments for optimal adhesion.

Adhesion of glass-ionomer cement sealers to bovine dentin conditioned with intracanal medications

This in vitro study assessed the adherence of glass-ionomer cement (GIC) root canal sealers to dentin conditioned by three endodontic intracanal medications. Three GIC sealers were used: (i) Ketac-Endo; (ii) KT-308, an experimental GIC sealer; and (iii) ZUT, a combination of KT-308 and a silver-containing zeolite (0.2% by weight). Superficial dentin of 120 bovine incisor crowns was used as a substrate. The dentin was irrigated with 2.6% NaOCI for 30 s and then blotted dry. One of the following conditioning media (n = 30) was maintained in contact with the dentin for 7 days: (i) Ca(OH)2 paste; (ii) chlorhexidine gluconate (CHX) liquid 0.12%; (iii) formocresol (FML) liquid; (iv) distilled water (dH2O) used as control. The GIC sealers were applied to the conditioned dentin, bench set for 90 min, stored in 100% humidity at 37 degrees C for 48 h, then tested to failure for shear bond strength (MPa) in an Instron machine. In the ZUT specimens, the shear bond strength did not differ significantly among those conditioned with Ca(OH)2, CHX, FML, and dH2O. For KT-308, the mean scores were significantly lower (p < 0.05) after conditioning with CHX than with dH2O. For Ketac-Endo, the mean scores were significantly lower after conditioning with Ca(OH)2 and FML than with dH2O (p < 0.05). Furthermore Ketac-Endo demonstrated significantly lower (p < 0.05) shear bond strength than KT-308 or ZUT to the dentin conditioned with Ca(OH)2 or FML. The results suggest that intracanal medications differentially influence the adhesion of various GIC sealers to root canal dentin.