Influence of intracoronal bleaching agents on the bond strength of MTA cements to composite resin and their surface morphology

Shear bond strength of calcium silicate-based cements to glass ionomers

BACKGROUND

A shear bond strength between the biomaterial and restorative material is crucial for minimizing bacterial microleakage and ensuring a favorable long-term prognosis for vital pulp therapy. This study aimed to conduct a comparative evaluation of the shear bond strength between calcium silicate-based biomaterials utilized in vital pulp treatment and various glass ionomer cement materials, both with and without the application of adhesive agents.

METHODS

A total of 270 acrylic blocks, each featuring cavities measuring 4 mm in diameter and 2 mm in depth, were prepared. Calcium silicate-containing biomaterials (ProRoot MTA, Medcem Pure Portland Cement, and Medcem MTA), following manufacturers' instructions, were placed within the voids in the acrylic blocks and allowed to set for the recommended durations. The biomaterial samples were randomly categorized into three groups based on the restorative material to be applied: conventional glass ionomer cement, resin-modified glass ionomer cement, and bioactive restorative material. Using cylindrical molds with a diameter of 3.2 mm and a height of 3 mm, restorative materials were applied to the biomaterials in two different methods, contingent on whether adhesive was administered. After all samples were incubated in an oven at 37 °C for 24 h, shear bond strength values were measured utilizing a universal testing device. The obtained data were statistically evaluated using ANOVA and post-hoc Tukey tests.

RESULTS

The highest shear bond strength value was noted in the Medcem MTA + ACTIVA bioactive restorative material group with adhesive application, while the lowest shear bond strength value was observed in the ProRoot MTA White + Equia Forte HT Fil group without adhesive application (P < 0.05).

CONCLUSION

Activa Bioactive Restorative may be considered a suitable restorative material in combination with calcium silicate-based biomaterials for vital pulp treatment. The application of adhesives to calcium silicate-based biomaterials can effectively address the technical limitations.

Impact of different intraorifice barriers on fracture resistance of non-vital bleached teeth

Background and Aim

This study aimed to evaluate the effects of bleaching agents on the fracture resistance of endodontically treated teeth using different intraorifice barrier (IOB) materials.

Materials and Methods

The endodontic treatment was performed for 160 mandibular premolars, and then, the teeth were divided into four groups according to the IOB: Ionoseal, Biodentine, ProRoot MTA, and TheraBase. Then, these teeth were subdivided into four subgroups (n = 10) based on the bleaching agents as distilled water (control), hydrogen peroxide 35% (HP), sodium perborate (SP), and carbamide peroxide 37% (CP). The access cavities were restored with composite resin after applying the bleaching agents for 7 days. The fracture resistance test was performed using a universal testing machine. Data were statistically analyzed, and the significance level was set at 5%. A scanning electron microscope was used to evaluate the effect of bleaching agents on the surfaces of IOBs.

Results

The highest fracture resistance values were observed in Biodentine groups with significant differences compared to Ionoseal and ProRoot MTA (P <.05). The distilled water groups showed significantly the highest fracture resistance compared to SP and HP groups (P <.05). There was no significant difference between SP, HP, and CP groups (P >.05). It was demonstrated that the morphological surface of the intact IOBs (control) was different from the surface of IOBs treated with bleaching agents.

Conclusion

The intracoronal bleaching procedures affected negatively the fracture resistance of the endodontically treated teeth.

Effect of Different Adhesive Strategies on the Microshear Bond Strength of Calcium-Silicate-Based Materials

Aim:

To evaluate the microshear bond strength (µSBS) of mineral trioxide aggregate and Biodentine to various resin-based materials using different adhesive strategies.

Materials and Methods:

Three resin-based materials—a self-adhering resin composite with or without acid etching (Vertise flow; Kerr, Orange, CA, USA), a conventional flowable composite with a total-etch adhesive (Filtek Ultimate Flowable; 3M ESPE, St. Paul, MN, USA), and a flowable resin-modified glass ionomer cement (RMGIC) without any surface modification (Ionoseal; VOCO GmbH, Cuxhaven, Germany)—and two calcium-silicate-based materials—Biodentine and BIOfactor mineral trioxide aggregate (MTA)—were tested. A total of 100 cylindrical acrylic molds were prepared. Biodentine and BIOfactor MTA were prepared and placed into the central holes on the molds. Specimens were divided into two main groups according to materials and into five subgroups ( n = 10). µSBS were evaluated using a µSBS testing device. The failure modes were examined under a stereomicroscope with magnification. They were categorized as adhesive, cohesive, or mixed. Data were analyzed using two-way analysis of variance (ANOVA) and Tukey test. The significance level was taken as α = 0.05.

Results:

It was observed that both calcium-silicate-based material type and resin-based material type influenced the µSBS significantly according to two-way ANOVA. Biodentine exhibited higher bond strength values than MTA. However, no statistically significant interaction was demonstrated between these factors ( P = .396). The µSBS values of intermediate materials to Biodentine and MTA were listed from the lowest to the highest as follows: RMGIC < Acid Etch + RMGIC < SARC (self-adhering resin composite) < FC (flowable composite) < Acid Etch + SARC.

Conclusion:

Self-adhering composites can be used on calcium-silicate-based materials in vital pulp treatments because of their mechanical properties. Acid-etching ensures high µSBS values. Although the µSBS of Biodentine were higher than MTA according to this study’s results, there was no statistically significant difference in µSBS of FC and acid-etched SARC to MTA.