The effects of endodontic substances and naturally reducing agents on the bond strength of epoxy resin-based sealer to root dentin

Comparative Evaluation of Antioxidant Effects of 25% Bamboo Salt and 3% Green Tea Extract on Push-out Bond Strength of AH Plus Sealer after Sodium Hypochlorite Irrigation: An In vitro Study

Context

Sodium hypochlorite (NaOCl), a commonly used intracanal irrigant, adversely affects the organic content of dentin, impacting the bond strength of sealer to root dentin.

Aim

The aim of the study was to compare the antioxidant effects of 25% bamboo salt and 3% green tea extract on the push-out bond strength of AH Plus sealer after NaOCl irrigation.

Subjects and Methods

Forty-five single-rooted mandibular premolars were selected, decoronated, and standardized to a length of 12 mm. During the canal preparation process, ProTaper Next rotary files were used, with each step accompanied by the irrigation of 5 ml of 5.25% NaOCl. Following the instrumentation, the canals were flushed with an additional 5 ml of 5.25% NaOCl and 17% ethylenediaminetetraacetic acid. The specimens were then categorized into three groups (n = 15 each): Group 1, treated with saline; Group 2, treated with a 25% bamboo salt solution; and Group 3, treated with a 3% green tea extract solution. From the coronal and middle thirds of each root, 1.5 mm thick slices were prepared. These slices were then tested for push-out bond strength using a universal testing machine.

Statistical Analysis

The data collected were subjected to one-way analysis of variance, followed by Tukey's post hoc analysis for detailed examination.

Results

The use of 5.25% NaOCl resulted in a significant reduction in the bond strength of AH Plus to dentin (P < 0.05). Among the treated groups, the samples irrigated with 3% green tea extract exhibited a notably higher push-out bond strength compared to those treated with 25% bamboo salt.

Conclusion

Within the limitations of this in vitro study, all experimental groups showed significant changes in push-out bond strength after antioxidant treatment.

Effect of Carbodiimide (EDC) on the Bond Strength Longevity of Epoxy Resin-based Endodontic Sealer to Root Dentin: An In-Vitro Study

PURPOSE

EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) can increase dentin bonding longevity. This study aimed to evaluate the effect of final irrigation of the root canal with EDC on the bond strength (BS) longevity of an epoxy resin-based root-canal sealer.

MATERIALS AND METHODS

Twenty maxillary canines were sectioned and standardized for root length at 17 mm. Roots were instrumented and distributed into 2 groups according to the final irrigation protocol: EDTA 17%+NaOCl 2.5% (C) and EDTA 17%+NaOCl 2.5%+EDC 0.5M (EDC). The canals were dried and filled with AH Plus (Dentsply Sirona). Three slices were obtained per third, and the first slice from each third was used for the immediate push-out test (i) followed by analysis of the failure pattern (n = 10); the second slice from each third was used for the push-out test after 6-month aging (A) followed by analysis of the failure pattern (n = 10); the third slice from each third was used to examine the adhesive interface under confocal laser scanning microscopy (CLSM) (n = 10). Data were analyzed with ANOVA, Fisher's exact and Kruskal-Wallis tests.

RESULTS

Higher BSs were found for EDC-A (5.6 ± 1.9) than for EDC-I (3.3 ± 0.7), C-i (2.5 ± 1.0) and C-i (2.6 ± 1.0) (p = 0.0001), while C-A values were in some cases similar to C-i and in others similar to EDC-i. No statistically significant difference was observed between the thirds (p > 0.05), except for EDC-i, which showed lower BS for the cervical (2.79 ± 0.46) compared to the apical third (3.8 ± 0.5), while the middle third in some cases had values similar to those of the apical and in others to the cervical third (3.2 ± 0.7) (p = 0.032). More mixed adhesive failures were found in the cervical third, and more adhesive failures to the sealer occurred in the middle and apical thirds (p = 0.014). A significant difference was observed between treatments in terms of adaptation of the adhesive interface, with a higher percentage of good adaptation using EDC (66.7%) than using C (40%), and a lower percentage of poor adaptation with EDC (10%) compared to C (20%) (p < 0.05).

CONCLUSION

Root canal irrigation with EDC increased the longevity of the adhesive interface of an epoxy resin-based root-canal sealer.

Investigation of five α-hydroxy acids for enamel and dentin etching: Demineralization depth, resin adhesion and dentin enzymatic activity

OBJECTIVES

Surface conditioning of enamel and dentin is a key step during adhesive restorative procedures and strategies. The aim of this study was to investigate the effectiveness of five α-hydroxy-acids (AHAs) as enamel and dentin surface etchants.

METHODS

Enamel and dentin specimens were prepared from human molars to determine the depth of demineralization by optical profilometry (Δz), the resin bond strength to enamel and dentin (μTBS), the micro-permeability of dentin-resin interfaces, and the gelatinolytic activity of dentin matrix induced by AHAs [glycolic (GA), lactic (LA), citric (CA), malic (MI) and tartaric (TA)] and controls [phosphoric (PA) and maleic (MA)]. All acids were prepared at 35% concentration. Adhesion studies employed Adper Single Bond Plus bonding system. Data were individually processed and analyzed by ANOVA, post-hoc tests and Pearson correlations (α = 0.05).

RESULTS

AHA exhibited statistically lower depth of demineralization of enamel and dentin (average 4 fold) than controls (p < 0.001). In enamel, MA and PA etching resulted in higher μTBS than AHA groups (p < 0.001). In dentin, GA, TA, CI and LA etching resulted in statistically similar μTBS than PA (p < 0.05). The hybrid-layer (HL) thickness and interfacial micro-permeability intensity were statistically lower for AHA groups (p < 0.05). A significant positive correlation was observed between the intensity of micro-permeability and the thickness of HL (p < 0.05). AHA etchants elicited lower dentin enzymatic activity than controls (p < 0.05).

SIGNIFICANCE

AHAs effectively etched enamel and dentin surfaces. In particular, GA and TA resulted in suitable μTBS and sealing ability as well as induced less gelatinolytic activity in dentin than PA and MA.

Design Variability of the Push-out Bond Test in Endodontic Research: A Systematic Review

INTRODUCTION

There is limited literature on the impact of testing variables on the push-out bond test (POBT). This review identified designs of the POBT used in the endodontic literature and aimed to determine which experimental variables may influence the push-out bond strength (POBS).

METHODS

A systematic review based on PRISMA guidelines was performed by searching the PubMed, SCOPUS, and Cochrane library databases using terms including push-out and dislocation resistance and descriptions of endodontic materials. Test variables assessed included method of root preparation, timing of sectioning compared with filling, thickness, diameter and taper of sections, and plunger size and velocity. The POBS of 3 common materials (gutta-percha and AH Plus, mineral trioxide aggregate, and Biodentine) were collected from investigations, and a comparison was attempted.

RESULTS

One hundred thirty-three studies assessed the POBS of root-filling materials, 68 assessed root repair cements/root-end filling materials, and 16 assessed orifice barrier materials other than mineral trioxide aggregate. There was significant variation in all of the assessed variables, resulting in a large range of reported values for the POBS of the various materials. Because of this heterogeneity in study design, no further statistical analysis of the impact of the test variables on POBS was possible.

CONCLUSIONS

There was considerable variation in the POBT design used in endodontic research. Greater standardization is required for future research as well as accurate reporting for all test variables to assess the impact of specific design variables on POBS.

A comparative evaluation of shear bond strength of composite resin to pulp chamber dentin treated with sodium thiosulfate and proanthocyanidin: An in vitro study

Aim:

Based on the importance of coronal sealing right after endodontic treatment, this in vitro study aimed to evaluate the difference of shear bond strength to pulp chamber dentin treated with sodium thiosulfate and proanthocyanidin (PA).

Materials and Methods:

Fifteen extracted mandibular molar teeth were decoronated at the level of cementoenamel junction horizontally. The individual teeth were then sectioned mesiodistally to expose the pulp chamber dentin using a diamond disc. The specimens were randomly divided into three groups (n = 10). Group A: control group, treated with 5.25% sodium hypochlorite (NaOCl) for 30 min followed by a final rinse with 17% ethylenediaminetetraacetic acid (EDTA) solution for 3 min; Group B: after pretreatment with NaOCl and EDTA, it is further treated with 5% sodium thiosulfate (Na₂S₂O₃) for 10 min; and Group C: after pretreatment with NaOCl and EDTA, it is further treated with 6.5% PA for 10 min. After drying the specimens, a bonding agent namely One Coat Bond SL (SwissTEC, Coltene) was applied to the pulp chamber dentin followed by a composite restoration (SwissTEC, Coltene). Each specimen was then tested under a universal testing machine at the dentin/resin interface to determine the shear bond strength.

Results:

Both the groups in which 5% Na₂S₂O₃ and 6.5% PA were used for 10 min showed bond strength that was found to be statistically higher than the positive control (P < 0.05).

Conclusion:

The use of Na₂S₂O₃ and PA can significantly increase the bond strength of composite resin to NaOCl/EDTA-treated dentin, allowing adhesive restorations to be immediately applied after endodontic treatment.