Effect of MTAD on the shear bond strength of self-etch adhesives to dentin

Extrusion bond strength of glass fiber post to radicular dentin after final irrigation using MTAD, EDTA, Pineapple peel extract, and riboflavin

INTRODUCTION

The present study aims to determine the effect of different post-space final irrigants ethylenediaminetetraacetic acid (EDTA), a mixture of Doxycycline citric acid and detergent (MTAD), Riboflavin (RF) and Pineapple peel extract (PPE) on the bond integrity of GFPs bonded to radicular dentin.

MATERIALS AND METHODS

Crowns of forty human mandibular premolars teeth were sectioned up to cementoenamel junction CEJ. Root canal treatment was performed. Gates Glidden drills were used to retrieve gutta-percha from the canal. All the specimens were randomly divided into four groups based on the final irrigant used. Group 1 (NaOCl with EDTA), group 2 NaOCl+ MTAD, group 3 NaOCl+RF and group 4 NaOCl+PPE. Cementation of glass fiber posts (GFPs) was performed using self-etch dual-cure resin cement. Sectioning was performed using a slow-speed saw from the coronal, middle, and apical third under constant water irrigation. A universal testing machine was used to assess push-out bond strength (PBS) and failure mode was evaluated using a Stereomicroscope at 40x magnification. One-way analysis of variance (ANOVA) and Tukey multiple comparison tests were used for statistical analysis (p=0.05).

RESULTS

Group 4 (2.5% NaOCl+ PPE) displayed the highest PBS at all three root levels (Cervical: 11.22±0.74 MPa, Middle: 8.99±0.97MPa, and Apical: 6.00±0.88 MPa). However, Group 1 (2.5% NaOCl+17% EDTA) demonstrated the lowest EBS (Cervical: 9.25±0.17 MPa, Middle: 7.01±1.84 MPa, and Apical: 4.41±0.17 MPa). Inter-group comparison displayed that PBS to be comparable between group 1 and group 3 (2.5% NaOCl+ Riboflavin) (Cervical: 9.74±0.41 MPa, Middle: 7.44±1.18 MPa, and Apical: 4.21±0.05 MPa) (p > 0.05). Whereas, group 2 (1.3% NaOCl+ MTAD) (Cervical: 9.32±1.36 MPa, Middle: 7.17±1.75 MPa, and Apical: 4.85±0.19 MPa) and group 4 demonstrated comparable values of PBS (p >0.05).

CONCLUSION

Pineapple peel extract and a mixture of Doxycycline citric acid and a detergent when used as a final irrigant demonstrated better bond integrity of GFPs to radicular dentin at all three levels coronal, middle and apical.

Effect of thermo-mechanical cycling and chlorhexidine on the bond strength of universal adhesive system to dentin

OBJECTIVES

This study evaluated the influence of thermo-mechanical cycling (TMC) on the bond strength (BS) of a universal adhesive system (UAS - Adper Single Bond Universal, 3M ESPE) to dentin treated or not with 0.2% chlorhexidine (CHX).

METHODS

Eighty human molars were flattened until reach the dentin and separated into 4 groups according to the bonding protocol: ENR Group: 37% phosphoric acid + 3-step etch-and-rinse adhesive system (ENR); UAS Group: UAS in self-etch mode; ENR + CHX Group: 37% phosphoric acid + CHX + ENR; UAS + CHX Group: CHX + UAS in self-etch mode. After treatments, teeth were restored (Filtek Z350, 3M ESPE). Samples (n = 10) were submitted to aging process: stored in distilled water at 37°C/30 days or TMC (ERIOS - 98N/1.6Hz + thermal cycling 5/37/55 °C - 1,200,000 cycles). Specimens were sectioned into sticks (1.0 mm2) and submitted to the microtensile test (Mechanical Test Machine - 0.5 mm/min). Fracture patterns and hybrid layer integrity were analyzed under Stereomicroscope and Scanning Electron Microscopy (SEM).

RESULTS

The BS results (3-way ANOVA, Bonferroni's test, α = 5%) showed that groups treated with CHX presented higher BS values than control groups; significant in all cases (p < .05), except for ENR submitted to TMC (p > .05). When CHX was applied and samples were cycled, UAS revealed higher BS (p < .05) than ENR. After TMC, cohesive fractures increased for UAS, regardless of CHX application. SEM analysis demonstrated different hybridization patterns for the adhesive systems tested.

CONCLUSION

The performance of the universal adhesive system used in self-etch mode was better than that of the 3-step etch-and-rinse adhesive system.

CLINICAL SIGNIFICANCE

Universal adhesive systems have been developed in order to simplify the dentin hybridization protocol. It is important to determine the longevity of the adhesive interface using these bonding materials after chewing.

The effect of silver nanoparticles on composite shear bond strength to dentin with different adhesion protocols

In Dentistry, restorative materials and oral bacteria are believed to be responsible for restoration failure. To make long-lasting restorations, antibacterial agents should be made. Inorganic nanoparticles and their nano composites are applied as good antibacterial agents.

Comparison of Endodontic Medicaments on Bond Strength of Fiber Post to Root Dentin Using Resin Cement

STATEMENT OF THE PROBLEM

Endodontic irrigants and medicaments may affect the bond strength of intracanal posts to root dentin.

PURPOSE

The aim of this study was to compare the effect of calcium hydroxide (Ca(OH)₂) and 2% chlorhexidine gel (CHX) on bond strength of fiber post cemented with resin cement to root dentin.

MATERIALS AND METHOD

This in vitro experimental study was conducted on 36 mandibular premolars. Canals were prepared using the step back technique. After root canal irrigation, the teeth were divided into three groups of 12. Ca(OH)₂ paste and CHX gel were used as intracanal medicaments in the first and second groups respectively. No intracanal medicament was used in the third group (control group). Access cavities were then sealed and the teeth were incubated for one week. The root canals were then filled using gutta percha and AH26 sealer and the teeth were incubated for 72 hours. Tooth crowns were then cut at the level of the cementoenamel junction and intracanal posts were placed. The teeth were mounted in auto-polymerizing acrylic resin, and incubated for one week .They were then sectioned into 1.5mm thick slices from their coronal surface using a fully automated cutting machine, and subjected to push-out test until failure. The load at debonding was recorded and data were analyzed using one-way ANOVA, post-hoc test and t-test. The coronal margin of the root was at the level of the surface of acrylic resin in the mold.

RESULTS

The mean bond strength was 4.45 MPa in the Ca(OH)₂, 2.45 MPa in the CHX and 2.48 MPa in the control group. The difference in this regard was statistically significant among groups (p= 0.04). The Ca(OH)₂ group had significant differences with the CHX and control groups (p= 0.03 and p= 0.02, respectively). The difference between the CHX and control groups was not significant (p= 0.974).

CONCLUSION

Based on the results, Ca(OH)₂ increased the bond strength of fiber post to root dentin but 2% CHX had no effect on bond strength.

Evaluation of push-out bond strength of AH26 sealer using MTAD and combination of NaOCl and EDTA as final irrigation

BACKGROUND

During endodontic procedures, the smear layer is formed as a result of mechanical instrumentation of the canal. Combination of ethylenediamine tetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) is widely used for removal of the smear layer. Application of Mixture of tetracycline, acid, and detergent (MTAD) as final irrigant subsequent to initial irrigation of 1.35% NaOCl has been proposed to increase clinical efficiency, biocompatibility and prolonged intra-canal antibacterial activity. Considering the importance of adhesion of endodontic sealers to the dentin walls of a prepared root canal, the present study evaluated push-out bond strength of AH26 sealer using final irrigation of MTAD and EDTA + NaOCl.

MATERIALS AND METHODS

Sixty five single-rooted teeth were prepared endodontically with the same chemomechanical technique and were randomly divided into three groups based on their final irrigation regimen: 17% EDTA + 5.25% NaOCl group (n =30), MTAD group (n =30) and control group (n =5). Obturation of the canals was performed with gutta-percha and AH26 sealer. All teeth were sectioned in order that two specimens of 1 mm thickness were obtained from the coronal and the middle one third of each root resulting in 60 specimens for each experimental group and 10 specimens for control group. For push-out test, universal-testing machine was used to exert a constant compressive apico-coronal load at a speed of 0.5 mm/min. Minimum amount of compressive load caused dislodgement was measured and converted into megapascal (MPa) scale. One-way analysis of variance and the post hoc Tukey test were used for statistical analysis of the data (α = 0.05).

RESULTS

In MTAD group, mean micro-push-out bond strength of AH26 sealer to dentin walls was obtained 2.23 MPa compared to 2.0 MPa for EDTA + NaOCl group. The mean bond strength of AH26 sealer to dentin walls was significantly greater using MTAD compared with combination of EDTA and NaOCl or saline.

CONCLUSION

MTAD final rinse significantly increased micro-push-out bond strength of AH26 sealer to canal dentin walls compared with EDTA + NaOCl.