Enhanced Antimicrobial Properties of Polymeric Denture Materials Modified with Zein-Coated Inorganic Nanoparticles.

Background: Polymeric denture materials can be susceptible to colonization by oral microorganisms. Zein-coated magnesium oxide nanoparticles (zMgO NPs) demonstrate antimicrobial activity. The aim of this study was to investigate the antimicrobial effect and adherence of different oral microorganisms on hybrid polymeric denture materials incorporated with zMgO NPs. Methods: Five types of polymeric denture materials were used. A total of 480 disc-shaped specimens were divided by material type (n=96/grp), then subdivided by zMgO NPs concentration: control with no nanoparticles and other groups with zMgO NPs concentrations of 0.3%, 0.5% and 1% by weight. Characterization of the polymeric denture materials incorporating zMgO NPs was done, and the antimicrobial activity of all groups was tested against four types of microorganisms: 1) Streptococcus mutans, 2) Staphylococcus aureus, 3) Enterococcus faecalis and 4) Candida albicans. The samples underwent an adherence test and an agar diffusion test. Experiments were done in triplicates. Results: The characterization of the hybrid samples revealed variation in the molecular composition, as well as a uniform distribution of the zMgO NPs in the polymeric denture materials. All hybrid polymeric denture materials groups induced a statistically significant antimicrobial activity, while the control groups showed the least antimicrobial activity. The agar diffusion test revealed no release of the zMgO NPs from the hybrid samples, indicating the NPs did not seep out of the matrix. Conclusion: The zMgO NPs were effective in reducing the adherence of the tested microorganisms and enhancing the antimicrobial activity of the polymeric denture materials. This antimicrobial effect with the polymeric dentures could aid in resisting microbial issues such as denture stomatitis.

Bond strength and surface roughness assessment of novel antimicrobial polymeric coated dental cement.

Resin cement integrated with zein-incorporated magnesium oxide nanoparticles has previously been found to inhibit oral microbes and decrease bacterial biofilm. However, the bond strength and surface features of this biomaterial have yet to be investigated. The objective of this study was to evaluate the shear bond strength, mode of fracture, and surface roughness of resin cement modified with zein-incorporated magnesium oxide nanoparticles. Characterization of the cement was performed by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. 126 human teeth were divided into 3 groups and cemented to lithium disilicate ceramic using resin cement with zein-incorporated magnesium oxide nanoparticles at concentrations of 0%, 1%, and 2% (n = 42). 21 samples of each group were subjected to the shear bond strength test, while the other 21 underwent thermocycling for 10,000 cycles before the test, after which all samples were evaluated for the mode of fracture. To assess surface roughness, resin cement disks were analyzed by a profilometer before and after undergoing thermocycling for 10,000 cycles. The shear bond strength of the cement with 1% and 2% nanoparticles was significantly higher than the control before thermocycling. The mode of fracture was found to be mainly adhesive with all groups, with the unmodified cement presenting the highest cohesive failure. There was no significant difference in surface roughness between the groups before or after thermocycling. The addition of zein-incorporated magnesium oxide nanoparticles to resin cement improved or maintained the shear bond strength and surface roughness of the resin cement.

Maximizing dental composite performance: Strength and hardness enhanced by innovative polymer-coated MgO nanoparticles.

INTRODUCTION: Zein-incorporated magnesium oxide nanoparticles (zMgO NPs) can influence the mechanical properties of dental materials. However, the effect of this addition on the mechanical properties of resin composite has yet to be investigated. The objective of this study was to add various concentrations of zMgO NPs to conventional, flowable, and bulk-fill composite and assess the effect on the compressive strength, flexural strength, and microhardness. METHODOLOGY: 150 samples each of conventional composite, flowable composite, and bulk-fill composite (n = 450) were enhanced with concentrations of zMgO NPs at 0 %, 0.3 %, 0.5 %, 1 %, and 2 % (n = 30). 10 samples of each group were randomly allotted to the compressive strength, flexural strength, or hardness test. Characterization of the specimens was performed by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Two-way ANOVA test was used to compare between groups, and one-way ANOVA followed by Tukey's test was done at p = 0.05 to determine significance. RESULTS: Characterization yielded a uniform distribution of nanoparticles in the matrix and the formation of a new hybrid composite that maintained its properties. Composite of all types enhanced with 0.3 % and 0.5 % zMgO NPs demonstrated a statistically significant increase in compressive strength, flexural strength, and hardness when compared to the control (p < 0.05). The bulk-fill composite with zMgO NPs concentrations of all groups demonstrated a statistically significant increase (p < 0.05) in hardness when compared to the control. CONCLUSION: The modified composites' compressive strength, flexural strength, and hardness improved or remained consistent. CLINICAL SIGNIFICANCE: An improved dental resin composite will enhance the quality of care and patient experience. The augmented strength and hardness of resin composite is desirable in prolonging the durability of the restoration.

Mechanical Behaviour of Novel Nanohybrid Resin Composite Using Two Light Cure Systems.

INTRODUCTION: Zein-incorporated magnesium oxide nanoparticles (zMgO NPs) were found to be effective against the bacteria S. mutans, S. aureus, E. faecalis and C. albicans, and can impart this antimicrobial effect on the resin composite it is integrated with. However, the effect of different light curing systems on the mechanical properties of this novel biomaterial has yet to be investigated. The objective of this study was to assess the effect of light-emitting diode (LED) and quarts-tungsten halogen (QTH) light curing systems on the compressive strength, flexural strength, and microhardness of bulk-fill resin composite modified with zMgO NPs. METHODOLOGY: A Teflon mold was used to fabricate 180 bulk-fill composite samples with concentrations of zMgO NPs at 0%, 0.3% and 0.5% (n = 60). Samples of each group were allocated to light curing by LED or QTH, after which 10 samples of each group were allotted to a mechanical test. Characterization of the specimens was performed by X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. Two-way ANOVA and Tukey's post-hoc test was conducted at P = .05 to determine significance. RESULTS: The characterization revealed a uniform distribution of nanoparticles in the matrix and the formation of a new hybrid composite that maintained its properties. The compressive strength of the 0.3% zMgO composite for the QTH group significantly increased, while the remaining groups underwent no significant change. There was no significant difference among the groups for the flexural strength and microhardness tests. CONCLUSION: The modified composites' compressive strength, flexural strength, and microhardness improved or remained consistent. Long-term clinical studies can further substantiate the enhanced resin composite. CLINICAL RELEVANCE: The modified composite will exhibit similar or improved mechanical properties whether an LED or QTH light cure device is used. The addition of an antimicrobial effect to bulk-fill resin composite will aid in the prevention of secondary caries.

Noninvasive assessment of novel nanohybrid resin cement adaptation using cross-polarization optical coherence tomography.

OBJECTIVES: Zein-coated magnesium oxide nanoparticles (zMgO NPs) can potentially improve cement adaptation to the tooth-restoration interface, which would aid in minimizing marginal leakage and secondary caries. The aim of this study was to assess the effect of incorporating zMgO NPs on the adaptation of self-adhesive resin cement using cross-polarization optical coherence tomography (CP-OCT) and scanning electron microscopy (SEM). METHODS: Resin inlays were fabricated to be cemented in Class-I cavities of extracted human molars. All specimens were randomly divided into five groups (n = 10), and the resin inlays were cemented using self-adhesive resin cement with various concentrations of zMgO NPs (0% [control], 0.3%, 0.5%, 1%, 2%). Characterization was done by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and SEM. The specimens were examined for interfacial adaptation under CP-OCT. Floor and wall adaptation measurements were analyzed by software on 20 B-scans, and samples were sectioned for interfacial measurement by SEM. RESULTS: Results for CP-OCT and SEM showed a statistically significant increase of adaptation in the floor and wall of resin cement filled with zMgO NPs compared to the control. The samples enhanced with 0.3% and 0.5% showed a statistically significantly better adaptation in floor and wall in CP-OCT and SEM. However, there was no significant difference between the 1%, 2%, and control groups for CP-OCT and SEM analysis. SIGNIFICANCE: The incorporation of zMgO NPs in self-adhesive resin cement can enhance the cement's properties by significantly improving its wall and floor adaptation.