Association of Graphene Silver Polymethyl Methacrylate (PMMA) with Photodynamic Therapy for Inactivation of Halitosis Responsible Bacteria in Denture Wearers

Abstract

(1) Background: Poor hygiene and denture presence in the oral cavity are factors that favor bacterial accumulation, the cause of halitosis and of various oral and general diseases. Aim: This study aimed to evaluate the possibility of inactivating bacteria associated with halitosis in acrylic denture wearers using polymethyl methacrylate resin enhanced with graphene silver nanoparticles and the effect of the resin association with extra oral photodynamic therapy. (2) Methods: Graphene silver nanoparticles in 1 and 2 wt% were added to a commercial acrylic resin powder. Three study groups containing samples from the three different materials were established. The first group was not exposed to the light treatment, and the other two were exposed to red light (laser and light emitting diode) after photosensitizer placement on the disk's surface. Samples were incubated with Porphyromonas gingivalis and Enterococcus faecalis. (3) Results: For both bacterial strains, inhibition zones were obtained, showing significant differences for the light-treated samples. (4) Conclusions: Denture resins with antibacterial properties associated with extra oral photodynamic therapy exhibited enhanced antibacterial effects. The procedure could be used as a safer and more efficient alternative technique against halitosis and oral infections in denture wearers.

Keywords: Enterococcus faecalis; Porphyromonas gingivalis; graphene; halitosis; photodynamic therapy.

Figure 1

Cross-polarized light microscopy images of the powders: (a) polymer spheres (M), (b) graphene-silver, and (c) polymer spheres coated with graphene-silver (P2).

Figure 2

FTIR spectra of the PMMA polymer (enhanced with G-Ag and control).

Figure 3

SEM images of the acrylic samples: (a)—PMMA, (b)—PMMA + 1%GO and (c)—PMMA + 2%GO.

Figure 4

Cell-viability testing in the study groups based on dilutions of the sample extract. Cells were exposed to binary dilutions of the sample extract (1/8, 1/4, ½ and undiluted) for 24 h and viability was evaluated by colorimetrical measurement of formazan production. Results are presented as OD. C = control sample, P1 = resin with 1 wt% graphene silver nanoparticles, P2 = resin with 2 wt% graphene silver nanoparticles. Comparative images of HGF cells treated with undiluted extract of each sample and then stained with Phaloidin-FITC are presented, bar = 20 µm. Yellow arrows show the normal morphological aspect of the HGF cells in all the groups.

Figure 5

Antimicrobial activity of the samples (placed on the culture medium) against Porphyromonas gingivalis (Pg) in 48 incubation hours. (Three experimental variants: simple variant = without light treatment; LED-treated variant; Laser-treated variant).

Figure 6

Antimicrobial activity of the samples (placed on the culture medium) against Enterococcus faecalis (Ef) in 48 incubation hours. (Three experimental variants: simple variant = without light treatment; LED-treated variant; Laser-treated variant).

Figure 7

The antimicrobial activity of the samples in different experimental variants (simple, LED, and Laser) for Porphyromonas gingivalis ATCC 33277 and Enterococcus faecalis ATCC 29212 P1 and P2 samples compared to control (C).

Figure 8

SEM investigation at 10,000× magnitude for (A) Porphyromonas gingivalis ATCC 33277 and for (B) Enterococcus faecalis ATCC 29212.