Antimicrobial and Mechanical Properties of Orthodontic Acrylic Resin Containing Zinc Oxide and Titanium Dioxide Nanoparticles Supported on 4A Zeolite

Abstract

Polymethyl methacrylate (PMMA) is widely used to manufacture removable orthodontic appliances. However, since the porous structure, cold-curing acrylic resins are susceptible to bacterial adhesion and colonization. The aim of this study was to investigate the antibacterial and mechanical properties of a cold-curing PMMA resin containing ZnO and TiO2 nanoparticles supported on the 4A zeolite. ZnO and TiO2 nanoparticles supported on the 4A zeolite were synthesized. Nanoparticles were added in three compositions as ZnO/4A, TiO2/4A, and ZnO/TiO2/4A at 2wt% and 4wt% concentrations to cold-curing acrylic resin powder (SR Triplex® Cold Ivoclar Vivadent AG, FL-9494 Schaan/Liechtenstein). X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and dynamic light scattering (DLS) were performed to investigate the nanocomposite characteristics. A direct test method was used to assess the antibacterial properties against Streptococcus mutans, Klebsiella pneumoniae, and Escherichia coli. The surface roughness of acrylic samples was measured with a profilometer. Flexural strength was evaluated by a three-point bending test, and one-way ANOVA and Tukey’s post hoc tests were used for statistical evaluation of the data. A p value of less than 0.05 was considered statistically significant. XRD confirmed the accurate crystalline structure of synthesized nanoparticles; FE-SEM images showed nanoparticle dispersion within polymerized acryl. The addition of 2 and 4 wt% of ZnO/4A, TiO2/4A, and ZnO/TiO2/4A caused colony reduction in all types of tested microorganisms more than 99% and 100%, respectively. The mean flexural strengths of acrylic specimens containing 2wt% and 4wt% of synthesized nanoparticles were significantly lower than those of the resin without nanoparticles. Fabricated samples showed favorable antibacterial properties but decreased flexural strength.

Nanocurcumin Release from Self-Cured Acrylic Resins; Effects on Antimicrobial Action and Flexural Strength

“…However, their results showed that the mean flexural strengths of acrylic specimens containing 2 wt% and 4 wt% of the used nanoparticles were meaningfully lower than the control group (resin without nanoparticles). Similar to our results, the samples indicated promising antibacterial possessions but decreased flexural strength [6].…”

“…Their results also showed an increase in antibacterial action with the enhancing of the concentrations of ZnO nanoparticles [14]. The study by Esmaeilzadeh et al showed that the adding of 2 and 4 wt% of ZnO, TiO 2 , and ZnO/TiO 2 produced high antimicrobial effects comparing the control group (the resin without nanoparticles) [6].…”

“…Moreover, removable orthodontic appliances may expand dental caries. So, the application of antimicrobial materials such as chlorhexidine mouthwash is recommended in orthodontic patients since mechanical clearing is not able to eliminate the microorganisms from all plaque-retaining parts [6]. Studies also have revealed main tooth decay and gingival inflammation problems after 4 months of eating and drinking without cleaning in patients using an orthodontic appliance [5,7,8].…”

Antifungal and physicochemical properties of polymerized acrylic resin containing strontium-modified phosphate-based glass

“…The use of mouthwashes, such as chlorhexidine, as supplemental antimicrobials is sometimes recommended for people with removable orthodontic appliances. However, chlorhexidine can cause side effects, such as altered taste and tooth discoloration [17]. Therefore, a need exists for antibacterial substances that improve the antimicrobial properties of the orthodontic appliance without adversely affecting its mechanical properties.…”

“…Therefore, a need exists for antibacterial substances that improve the antimicrobial properties of the orthodontic appliance without adversely affecting its mechanical properties. Previous studies proposed the addition of antimicrobial materials, such as chitosan, silver nitrate, silver nanoparticles, zinc oxide, and titanium dioxide nanoparticles to the resins of removable orthodontic appliances [17][18][19]. These studies showed excellent antibacterial and antifungal properties; however, some reported low biocompatibility and a tendency to reduce material strength, which promotes fracturing.…”