The bond strength of adhesive resins to AH plus contaminated dentin cleaned by various gutta-percha solvents

Effect of cleaning materials on microtensile bond strength of resin composite to primary dentin contaminated with root canal sealers

BACKGROUND

There have been no studies on the bond strength of adhesives with dentin surfaces contaminated with root canal sealers in primary teeth without underlying permanent teeth germs. This study investigated the cleaning materials used for primary tooth dentin contaminated with root canal sealers. The aim was to increase the success rate of root canal treatment in pedodontics clinics and retain the teeth for longer.

METHODS

The occlusal enamel layer was removed, followed by the application of root canal sealers (AH Plus or MTA Fillapex) to the dentin and cleaning using different irrigation solutions (saline, NaOCl, and ethanol). The specimens were restored using a self-etch adhesive and composite. Sticks with a thickness of approximately 1 mm were obtained from each sample, and the bond strengths were measured using a microtensile testing device. The interfacial morphology of the bonded space was evaluated using scanning electron microscopy.

RESULTS

The control and AH Plus saline groups had the highest bond strengths. The groups cleaned using ethanol had the lowest bond strengths (p < 0.01).

CONCLUSION

Cleaning the dentin with saline-soaked cotton pellets provided the best bond strengths. Therefore, saline is the most effective material for removing both epoxy resin- and calcium silicate-based root canal sealers from the access cavity.

Influence of Phosphoric Acid Etching on Bond Strength for Calcium Silicate-Based Sealers

INTRODUCTION

This study evaluated the microtensile bond strength of calcium silicate-based sealers and AH Plus depending on the use of phosphoric acid (PA) etching before immediate resin restoration.

METHODS

Exposed dentin surfaces of extracted human third molars were randomly assigned to 3 groups depending on sealer type (AH Plus [Dentsply DeTrey], CeraSeal [Meta Biomed Co.], and EndoSeal MTA [Maruchi]). Half of the samples were treated with PA for 30 seconds, and the other half were cleaned with water. Completely untreated specimens were used as controls. Self-etching adhesive (Clearfil SE Bond, Kuraray) was applied, and composite resin (Tetric N-Ceram, Ivoclar Vivadent) was used to create build-ups. After 24 hours, the microtensile bond strength was measured (EZ Test, Shimadzu Co.). The failure mode was determined by light microscopy and scanning electron microscopy. One-way analysis of variance with the Bonferroni correction was used to analyze the data (p<0.05).

RESULTS

The bond strength of the water-washed dentin surfaces in the calcium silicate-based sealer groups did not differ significantly from those of the control surfaces, but the PA-pretreated surfaces exhibited relatively low bond strength. The AH Plus-treated group had lower bond strength than the control group when no PA treatment was applied, but PA treatment restored the bond strength. The adhesive failure mode was most frequently found in the AH Plus group without PA etching.

CONCLUSIONS

When a water-soluble calcium silicate-based sealer is used, sufficient bond strength can be obtained by washing with water alone, with no need for PA use.

Protocols for cleaning the incisor access cavity contaminated with epoxy resin sealer

This study compared different methods for cleaning the sealer-contaminated access cavity of upper incisors. After standard endodontic access, the canals of 50 extracted maxillary incisors were chemomechanically prepared and obturated with gutta-percha and epoxy resin sealer. Teeth were randomly assigned to one of five different pulp chamber cleaning protocols (n = 10): air/water spray, ethanol-saturated cotton pellet (CP), ethanol-saturated microbrush reaching the root filling (MB), MB + air polishing (PROPHYflex; KaVo), or MB + etching with 37% phosphoric acid. Each tooth was split and the sealer-covered area of the pulp chamber was determined on images taken before and after cleaning using image analysis software. The sealer-covered area was compared across groups using one-way ANOVA. Greatest mean sealer-covered area reduction was observed for MB + etching (98.0%), MB + air polishing (95.2%), and MB alone (92.8%), yielding a significantly higher sealer-covered area reduction than after air/water spray (8.3%) and ethanol-saturated cotton pellet (53.4%). The upper incisor access cavity is best cleaned with an ethanol-saturated microbrush reaching up to the root filling, followed by air/water spraying and etching. The use of cotton pellets should be discouraged.

The efficacy of different sealer removal protocols on the microtensile bond strength of adhesives to a bioceramic sealer-contaminated dentin

Background

The optimal bonding of adhesives to dentin requires the sealer to be completely removed from the dentinal walls.

Aim

This study compared the efficacy of different sealer removal protocols on the microtensile bond strengths (MTBS) of single-step adhesives to a calcium silicate-based bioceramic root canal sealer-contaminated dentin.

Materials and Methods

Standardized box-shaped Class I cavities were prepared in human lower third molars (N = 50). All cavities were contaminated with a bioceramic root canal sealer (Endosequence BC Sealer, Brasseler, Savannah, USA), except the control group (G1) cavities. For the experimental groups, contaminated dentin surfaces were wiped with a dry cotton pellet (G2), wiped with a cotton pellet saturated with water (G3), rinsed with the air/water spray (G4), and passively applied aqueous ultrasonic energy with an ultrasonic scaler (G5) before the restoration procedure. All the cavity surface was restored with a one-bottle universal adhesive and composite resin. All the specimens were subjected to both thermocycling (2,500 thermal cycles from 5 to 55°C, with a 30-s dwelling time and a 10-s transfer time) and mechanical loading (50 N load for 100,000 cycles). The restored specimens were sectioned into resin-dentin beams for MTBS evaluation. Additional specimens were prepared for the scanning electron microscopy (SEM) to examine the dentin-adhesive interface (n = 10).

Results

No significant difference was found between the mean bond strengths of the groups. In SEM examination, no residual sealer was found in any group.

Conclusion

Calcium silicate-based bioceramic sealer was removed from the dentin surface with all removal protocols when evaluated with MTBS after the thermal and mechanical cycle tests.

Microtensile bond strength to sealer-contaminated dentin after using different cleaning protocols

Background/purpose

Sealer residues on dentin may affect bonding to restorative materials. This study aimed to evaluate the bond strength to sealer-contaminated dentin after using different cleaning protocols.

Materials and methods

Freshly extracted bovine incisors were prepared and exposed the buccal pulp chamber dentin, obtaining segments measuring 5 mm × 5 mm with a height of 3 mm. The segments were randomly distributed into 4 groups (n = 7) according to different protocols. Control group: no contamination was performed. In the three experimental groups, the segments were contaminated with epoxy resin-based sealer for 5 min, and different cleaning protocols were performed. Acetone group: acetone-saturated cotton pellets were used to wipe the sealer. Ultrasound group: ultrasonic ET-20D tip cleaning. Acetone combined with ultrasound group: cleaning with acetone-saturated cotton pellets and ultrasonic tip. All segments were bonded using a self-etch adhesive. Two samples in each group were scanned by swept-source optical coherence tomography (SS-OCT) to evaluate sealer residues. A microtensile test was performed on the remaining 5 samples, which were built up with composite resin.

Results

Sealer residues were observed in 3 of 14 (21.4%) sections of acetone group by SS-OCT. Compared to the control, ultrasound alone or in combination with acetone preserved the bond strength (P > .05). The ultrasound group exhibited the highest bond strength (39.38 MPa), which differed from that of the acetone group, which provided the lowest bond strength (32.88 MPa) (P < .05).

Conclusion

Cleaning epoxy resin-based sealer-contaminated dentin surfaces using ultrasound or combined with acetone could preserve the bond strength.

Effects of dentine surface cleaning on bonding of a self-etch adhesive to root canal sealer-contaminated dentine

OBJECTIVES

To compare the effectiveness of different sealer cleaning methods on bonding of a self-etch adhesive to root canal sealer-contaminated dentine.

METHODS

Forty-nine extracted molars were divided into seven groups. Dentine surfaces were exposed and cotaminated with a thin layer of epoxy resin-based sealer (AH Plus (AHP)) or zinc oxide eugenol-based sealer (Pulp Canal Sealer (PCS)). Three cleaning protocols were examined: dry cotton pellet, 70% ethanol-saturated cotton pellet or a surfactant-based cleaner (Katana^TM Cleaner (KC), Kuraray Noritake Dental Inc.). Uncontaminated dentine served as control. The dentine surfaces were bonded with a two-step self-etch adhesive and restored with resin composite. Bond strength testing was performed using a microtensile approach. Two teeth from each group were used for scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The pulpal floor of the teeth was covered with sealer and cleaned. The percentage of zinc/zirconium on the dentine surface was detected to indicate the amount of remnant sealer.

RESULTS

Tensile bond strength for uncontaminated dentine control was 46.4±7.3 MPa; bond strength decreased significantly for the dry cotton group (29.6±4.2 MPa for AHP, 24.7±4.7 MPa for PCS, p<0.05). Both ethanol and KC restored bonding performance after cleaning, with no significant difference from the control. Significantly lower MTBS was observed for the ZOE/ethanol subgroup (38.9±5.1 MPa). Cleaner surfaces and less zinc/zirconium elements were identified by SEM/EDX after cleaning with ethanol or KC.

CONCLUSIONS

Katana^TM Cleaner decontaminates root canal sealer-smeared dentine surfaces effectively and restores the bonding performance of a self-etch adhesive to dentine.

CLINICAL SIGNIFICANCE

The surfactant-based Katana^TM Cleaner, originally designed for cleaning zirconia surfaces prior to adhesive bonding, may be used as for cleaning dentine that has been contaminated with unset root canal sealers after root canal treatment to restore the bonding strength of a self-etch adhesive to sealer-contaminated dentine.

Influence of adjunctive photodynamic therapy (curcumin) on the extrusion bond strength of radicular dentin to contemporary root canal sealers

OBJECTIVE

The aim was to compare Photodynamic therapy (PDT) as an adjunct to NaOCl and EDTA on the extrusion bond strength (EBS) of AH Plus (AH), Sealapex (SA) and MTA Fillapex (MF) root canal sealers.

MATERIALS AND METHOD

Root canal treatment for human teeth (n = 60) using protaper universal system was performed followed by irrigation with NaOCl/ EDTA. Samples were divided (n = 30) based on disinfection technique, NaOCl/EDTA and NaOCl/EDTA with PDT (Curcumin-PS-CP) as an adjunct. Specimens were divided in three subgroups (n = 10) based on sealers used (Gp 1-Na-E-AH, Gp 2-Na-E-PDT-AH, Gp 3-Na-E-SA, Gp 4-Na-E-PDT-SA, Gp 5-Na-E-MF & Gp 6-Na-E-PDT-MF). Canals were dried and obturated followed by sectioning at coronal and middle third. EBS testing was performed using a universal testing machine (UTM) and modes of failure were assessed. Analysis of variance (ANOVA) and Tukey multiple comparison tests were used to compare the means of EBS. (p < 0.05).

RESULTS

Sealers showed a significant influence on EBS, as Gp 1 (Co: 9.21 ± 0.62, Mid: 8.54 ± 0.55) and Gp 2 (Co: 7.11 ± 0.68, Mid: 7.30 ± 0.37) showed higher EBS than Gp 3 (Co: 5.21 ± 0.63, Mid: 4.36 ± 0.83) and Gp 4 (Co: 5.39 ± 0.72, Mid: 4.46 ± 0.74). Gp 5 (Co: 9.04 ± 0.13, Mid: 8.14 ± 0.91) and Gp 6 (Co: 8.67 ± 0.42, Mid: 8.07 ± 0.07) exhibited higher EBS than Gp 3 and Gp 4 specimens. Adjunctive use of PDT for AH sealer (Gp 2) showed decreased EBS compared to Gp 1 specimens. EBS remained comparable for both MTA-Fillapex and Sealapex with and without PDT.

CONCLUSION

AH Plus (Gp 1 and 2) and MTA-Fillapex (Gp 5 and 6) sealers displayed better EBS compared to Sealapex (Group 3 and 4). Adjunctive Application of PDT (CP) did not show a significant improvement in bond strength of sealers to root dentin.

Prevention of coronal discoloration induced by root canal sealer remnants using Dentin Bonding agent: An in vitro study

Introduction

Among the various causes of tooth discoloration after root canal treatment, percolation of sealer remnants into the dentinal tubules of the pulp chamber is the most common cause.

Objectives

The aim of this study is to evaluate the efficacy of dentin bonding agent (DBA) in preventing coronal discoloration caused by four different root canal sealers- MTA Fillapex, Sealapex, Zical and Z. O. B seal at different time intervals by measuring chromatic alterations using digital images analysis method.

Methodology

Ninety mandibular premolars were collected and sectioned at 1 mm below the cementoenamel junction. Standard access cavity preparations of dimensions (depth-3 mm, width-0.8 mm, and length-3 mm) were prepared with a No. 245 bur through the cervical access. Following the standard irrigation protocol, specimens were then randomly divided into nine groups (four groups without DBA [1-4] +4 groups with DBA [5-8] +1 negative control [9]). In Groups 1-4, four different root canal sealers (MTA Fillapex, Sealapex, Zical, and Z.O.B seal) were applied to the walls of the pulp chamber. For Groups 5-8, the samples were etched with 37% phosphoric acid and DBA application was done before the respective root canal sealer application. The cervical access in all specimens was sealed using glass ionomer cement. Digital photographs were taken under standard lighting and environmental conditions at different time intervals: preprocedural, postprocedural, and after 1, 2, 3, and 4 months. These images were analyzed using Adobe Photoshop CS6 from which laboratory values and subsequently Delta E values were obtained.

Results

Statistical analysis performed using repeated measures ANOVA and post hoc Tukey's tests show that the groups with DBA application had significantly lower mean Delta E values (P < 0.05) compared to the groups without DBA application.

Conclusion

DBAs applied to the dentinal walls of the pulp chamber before obturation can effectively reduce the sealer-induced coronal discoloration.

Effect of endodontic sealers on bond strength of restorative systems to primary tooth pulp chamber

Background/purpose

Although current literature suggests that root canal sealers affect the bonding ability of restorative systems to pulp chamber dentin of permanent teeth, primary teeth have not been investigated. This study intended to evaluate the microtensile bond strength (μTBS) of three restorative systems to pulp chamber dentin in primary teeth and to determine the effect of two different root canal sealers on the μTBS.

Materials and methods

Ninety primary molars were used in this study. The teeth were randomly divided into three main groups according to canal sealers: (1) control (without sealer); (2) Metapex; and (3) zinc-oxide eugenol. The main groups were further divided into three subgroups depending on the coronal restorative system: (1) compomer (Prime Bond NT + Dyract EXTRA); (2) composite (Clearfil Tri-S Bond + Clearfil Photo Posterior); and (3) resin-modified glass ionomer (Fuji II LC). After restoration, the buccal wall of the pulp chamber was sectioned to obtain sticks (1 mm × 1 mm). The μTBS was then measured. Data were analyzed with two-way analysis of variance, followed by a posthoc test. The interfacial morphology of the bonded space was evaluated using scanning electron microscopy.

Results

In the control group, a significant difference was observed only for the μTBS of the composite (P < 0.05). Compared with the control groups, Metapex and zinc-oxide eugenol significantly reduced the μTBS of restorative systems (P < 0.05).

Conclusion

Composite materials seemed to bond to pulp chamber dentin in primary teeth with a higher strength than compomer and resin-modified glass ionomer. Metapex and zinc-oxide eugenol canal filling materials reduced the bond strength of all three restorative systems.

Effect of different gutta-percha solvents on the microtensile bond strength of various adhesive systems to pulp chamber dentin

OBJECTIVES

The aim of this study was to evaluate the effect of different endodontic solvents on the microtensile bond strength (μTBS) of various adhesives to pulp chamber dentin.

MATERIAL AND METHODS

A total of 120 human third molars were selected. Canals were prepared with the ProTaper Universal system and obturated. The access cavities were then restored with resin composite. After 1 week, a retreatment procedure was applied as follows: control, no solvent was applied to the pulp chamber and experimental groups, three different solvents (chloroform, eucalyptol, and orange oil) were applied to the pulp chamber for 2 min. The canal filling was removed and calcium hydroxide (Ca[OH]₂) was placed into the canals. After 7 days, the Ca(OH)₂ was removed from the canals and the canals were re-obturated. Teeth were then divided into three subgroups according to the adhesive used. The samples were restored with a nanohybrid resin composite using three different adhesives: Clearfil SE Bond (CSE), Adper Easy One (AEO), and Single Bond 2 (SB2). The samples were aged with thermocycling. Teeth were sectioned, and a total of 20 dentin sticks were obtained for each subgroup. μTBS testing was then performed. The debonded surfaces were evaluated using scanning electron microscopy (SEM) analysis. Data were analyzed using two-way ANOVA and Tukey's post hoc tests.

RESULTS

Chloroform showed statistically lower mean μTBS values (14 ± 7.2 MPa) than control group did (19.2 ± 6.1 MPa) (p < 0.05). Orange oil (18.1 ± 6.3 MPa) and eucalyptol (16.9 ± 6.8 MPa) did not reduce the mean μTBS statistically (p > 0.05). Chloroform showed significantly lower bond strength for all adhesives (p < 0.05). Whereas orange oil did not reduce the mean μTBS values of all adhesive systems significantly (p > 0.05), eucalyptol reduced the μTBS values of all the groups, but the results were only statistically significant for SB2 (p < 0.05). CSE showed statistically higher bond strength (20.4 ± 6.8 MPa) than AEO (14.6 ± 5.3 MPa) and SB2 (16.3 ± 7.2 MPa) did (p < 0.05). There were no statistical differences between AEO and SB2 (p > 0.05). According to the SEM analysis of the debonded surfaces, adhesive failures were the most common type in all the groups, followed by mixed failures.

CONCLUSIONS

While chloroform reduced the mean bond strength of the adhesive resins, orange oil did not affect the bond strength of the adhesives. The effect of eucalyptol on bond strength depended on the type of adhesive system.

CLINICAL RELEVANCE

This study shows that endodontic solvents could affect the microtensile bond strength of adhesives to pulp chamber dentin.