Efeito da própolis vermelha na durabilidade e resistência de união da interface adesiva

Abstract

The red propolis from Alagoas (RAP) has gained attention due to its well-known antimicrobial and antioxidant properties, which may contribute to the long-term preservation of the hybrid layer. Thus, the aim of this study was to synthesize and characterize a dentin adhesive incorporated with red propolis extract from Alagoas (EPV) and to evaluate its effect on the durability and bond strength of the adhesive interface. This is an in vitro and ex vivo experimental laboratory study, which adopted an animal research model. The hydroethanolic extract of red propolis from Alagoas (EPV) was prepared at a concentration of 500 µg/mL. Sixty sound bovine mandibular incisors (n=60) were selected and randomly distributed into three experimental groups according to the adhesive system used: Group AEPV500 – Experimental Adhesive with propolis; Group SB – Single Bond 2/3M ESPE; Group AE – Experimental Adhesive without propolis. The chemical markers of PVA were identified using High-Performance Liquid Chromatography (HPLC). The experimental adhesive containing propolis (Group AEPV500) was synthesized by mixing monomers, inorganic fillers, photoinitiators, ethanol, and the EPV extract. The commercial adhesive Single Bond 2/3M ESPE (Group SB) was used as a positive control, and the experimental adhesive without propolis (Group AE) as a negative control. Tests were performed 24 hours and one year after polymerization, with the specimens stored in artificial saliva. Adhesive characterization was performed using Fourier-Transform Infrared Spectroscopy (FTIR), Degree of Conversion (DC), and Radiopacity assessment. Wettability was evaluated by contact angle measurement at three different times: T0, T1 (10 seconds), and T2 (20 seconds) after droplet application. Bond strength was measured by microtensile bond strength (μTBS) testing, followed by fracture mode analysis. Qualitative evaluation of nanoleakage using silver nitrate infiltration at the adhesive interface was performed by Scanning Electron Microscopy (SEM). Statistical analysis was carried out using Student’s t-test and ANOVA with Tukey’s post hoc test (p<0.05). Several flavonoids were identified in the EPV hydroethanolic extract. The adhesives tested showed an appropriate degree of conversion, with a significant increase observed in the AEPV500 group. All tested adhesives appeared radiolucent in radiographic images and exhibited hydrophilic behavior in wettability analysis, with a decrease in contact angle over time. Microtensile bond strength (μTBS) comparisons at 24 hours and one year showed similar performance across all groups; however, AEPV500 achieved the highest bond strength (35.13 MPa at 24h and 33.89 MPa at one year). Adhesive failure was the predominant fracture mode. SEM analysis revealed silver nitrate deposits along the adhesive interface in AE and SB groups, while no deposits were observed in the AEPV500 group, suggesting improved dentin sealing. It can be concluded that incorporating EPV at 500 µg/mL into the experimental adhesive increased the degree of conversion and promoted both immediate and long-term bond strength of the adhesive interface.