Towards the development of self-healing and antibacterial dental nanocomposites via incorporation of novel acrylic microcapsules

Abstract

Objective: The main aim of the current work was to develop the novel self-healing dental composites contained poly(methyl methacrylate) (PMMA) microcapsules. The effects of PMMA microcapsule content in self-healing performance and mechanical properties of dental composites including flexural strength, flexural modulus, and fracture toughness were discussed. The antibacterial activity and non-toxicity properties of optimum self-healing dental composites were also investigated.

Methods: Novel acrylic microcapsules were prepared using triethylene glycol dimethacrylate (TEGDMA) as healing agent and PMMA as microcapsule shell via solvent evaporation method. The silica nanoparticles with the mean size of 15-20 nm were treated by 3-methacryloxypropyltrimethoxysilane (MPS) to enhance their adhesion and dispersion within the acrylic matrix of composite. Acrylic microcapsules with mass fractions of 0%, 5%, 10%, and 15% were added into a mixture of acrylic resins and MPS-grafted SiO₂ nanoparticles. The strength and elastic modulus of dental composites were measured by the flexural test. The single edge V-notched beam (SEVNB) method was applied to investigate fracture toughness (K_IC) and healing efficiency. The results were then statistically analyzed using one-way analysis of variance (ANOVA) at the confidence level of 0.95.

Results: Acrylic microcapsules were synthesized with the mean size around 30 µm and the core content of about 15 wt%. The grafting percentage of MPS surface modifier onto SiO₂ nanoparticles was measured 3.2%. The incorporation of PMMA microcapsules into the dental composites had no significant effect on flexural properties. The self-healing dental composites also indicated the high efficient healing performance in the range of 78-121%. The self-healing dental composites also exhibited impressive antibacterial activity against Streptococcus mutans (S. mutans). The MTT assay also revealed that the incorporation of acrylic microcapsules in dental composites has no cytotoxicity effects. SIGNIfiCANCE: In the current study, for the first time, the self-healing dental nanocomposites contained acrylic microcapsules were prepared with excellent healing performance and antibacterial properties.

Keywords: Antibacterial activity; Dental composites; Fracture toughness; Microcapsule; Self-healing.