The durability of resin-dentine bonds are enhanced by epigallocatechin-3-gallate-encapsulated nanohydroxyapatite/mesoporous silica

Epigallocatechin gallate-immobilized antimicrobial resin with rechargeable fluorinated synergistic composite for enhanced caries control

OBJECTIVES

Given the global prevalence of dental caries, impacting 2.5 billion individuals, the development of sophisticated prevention filling materials is crucial. Streptococcus mutans, the principal caries-causing strain, produces acids that demineralize teeth and initiate dental caries. To address this issue, we aimed to develop a synergistic resin-based composite for enhancing caries control.

METHODS

The synergistic resin composite incorporates fluorinated kaolinite and silanized Al2O3 nanoparticle fillers into an epigallocatechin gallate (EGCG) immobilized urethane-modified epoxy acrylate (U-EA) resin matrix, referred to the as-prepared resin composite. The EGCG-modified TPGDA/U-EA network was synthesized by preparing methacrylate-functionalized isocyanate (HI), reacting it with EGCG to form HI-EGCG, and then incorporating HI-EGCG into the TPGDA/U-EA matrix. The lamellar space within the kaolinite layer was expanded through the intercalation of acrylamide into kaolinite, enhancing its capability to adsorb and release fluoride ions (F-). The layered structure of acrylamide/ kaolinite in the U-EA resin composite acts as a F- reservoir.

RESULTS

The physico-mechanical properties of the as-prepared resin composites are comparable to those of commercial products, exhibiting lower polymerization shrinkage, substantial F- release and recharge and favorable diametral tensile strength. The immobilized EGCG in the composite exhibits potent antimicrobial properties, effectively reducing the biofilm biomass. Furthermore, the synergistic effect of EGCG and fluorinated kaolinite efficiently counteracts acid-induced hydroxyapatite dissolution, thereby suppressing demineralization and promoting enamel remineralization.

SIGNIFICANCE

Our innovative EGCG and fluoride synergistic composite provides enhanced antimicrobial properties, durable anti-demineralization, and tooth remineralization effects, positioning it as a promising solution for effective caries control and long-term dental maintenance.

Biomodification of eroded and abraded dentin with epigallocatechin-3-gallate (EGCG)

This study aimed to evaluate in vitro the effects of epigallocatechin-3-gallate (EGCG) as a biomodifier of eroded and abraded dentin. Forty dentin specimens were obtained from the buccal surface of bovine teeth. The specimens were randomly distributed in 4 groups according to dentin substrate: sound or eroded/abraded and dentin biomodification: with 0.5% EGCG and no biomodification (control group). Specimens were subdivided according to aging time: 24 h and 3 months for the analysis of microtensile bond strength (n = 10), morphology of the adhesive interface by SEM (n = 3) and dentin micropermeability by fluorescence microscope (n = 8). Statistical analysis was performed using SPSS system version 20.0 with a significance level of 5%. The results revealed that the control group with eroded-abraded dentin exhibited the lowest bond strength values at 24 h and 3 months. However, the application of 0.5% EGCG as a biomodifier significantly increased bond strength on both sound and eroded-abraded substrates. After 3 months, all groups exhibited an adhesive interface with a more intense fluorescence in the adhesive layer, indicating an increase in porosity at the interface. In conclusion, the EGCG application as a biomodifier enhanced bond strength on both sound and eroded-abraded dentin substrates, however, adhesive interfaces are more regular when restorations are performed on sound dentin, regardless of the biomodification with EGCG.

Natural Bioactive Epigallocatechin-Gallate Promote Bond Strength and Differentiation of Odontoblast-like Cells

The (-)-Epigallocatechin-gallate (EGCG) metabolite is a natural polyphenol derived from green tea and is associated with antioxidant, biocompatible, and anti-inflammatory effects.

OBJECTIVE

To evaluate the effects of EGCG to promote the odontoblast-like cells differentiated from human dental pulp stem cells (hDPSCs); the antimicrobial effects on Escherichia coli, Streptococcus mutans, and Staphylococcus aureus; and improve the adhesion on enamel and dentin by shear bond strength (SBS) and the adhesive remnant index (ARI).

MATERIAL AND METHODS

hDSPCs were isolated from pulp tissue and immunologically characterized. EEGC dose-response viability was calculated by MTT assay. Odontoblast-like cells were differentiated from hDPSCs and tested for mineral deposition activity by alizarin red, Von Kossa, and collagen/vimentin staining. Antimicrobial assays were performed in the microdilution test. Demineralization of enamel and dentin in teeth was performed, and the adhesion was conducted by incorporating EGCG in an adhesive system and testing with SBS-ARI. The data were analyzed with normalized Shapiro-Wilks test and ANOVA post hoc Tukey test.

RESULTS

The hDPSCs were positive to CD105, CD90, and vimentin and negative to CD34. EGCG (3.12 µg/mL) accelerated the differentiation of odontoblast-like cells. Streptococcus mutans exhibited the highest susceptibility < Staphylococcus aureus < Escherichia coli. EGCG increased (p < 0.05) the dentin adhesion, and cohesive failure was the most frequent.

CONCLUSION

(-)-Epigallocatechin-gallate is nontoxic, promotes differentiation into odontoblast-like cells, possesses an antibacterial effect, and increases dentin adhesion.

MODERN TRENDS AND PERSPECTIVES OF THE DEVELOPMENT OF ADHESIVE DENTISTRY. INNOVATIVE TECHNIQUES FOR THE APPLICATION OF ADHESIVE SYSTEMS

OBJECTIVE

The aim: To study the latest approaches to optimizing the composition and application protocols of modern adhesive systems, which are used during the restoration of defects in hard dental tissues with restorative materials.

PATIENTS AND METHODS

Materials and methods: Thirty articles published between January 1, 2020 and February 1, 2023 in the scientific databases PubMed, Scopus, and Google Scholar were selected. The selected scientific works contained the results of laboratory studies, systematic reviews, meta-analyses of the physical and mechanical characteristics of adhesive systems with a modified composition or application protocols different from the instructions of the manufacturing companies.

CONCLUSION

Conclusions: The most promising directions for improving adhesive systems are modifications of the composition and protocols of their use with the aim of deactivating matrix metalloproteinases, improving the structure of the hybrid layer due to the creation of a three-dimensional mesh of collagen fibres with optimal properties, the introduction of antimicrobial agents to slow down the growth of bacterial colonies along the line of the adhesive joint. The available research results of modified adhesive systems are often contradictory, which determines the need to develop standardized test methods to obtain more reliable indicators of their physical, mechanical and biological properties. In some cases, the consequences of non-compliance with the recommendations of the manufacturing companies are a significant deterioration of the characteristics of the hybrid layer, adhesive strength, marginal fit, which, in turn, explains the need for further search for an optimized composition and techniques for applying bonding agents to improve the prognosis of restorative treatment.