Antimicrobial Acrylic Denture Development

Introduction

• The global elderly population is increasing, and oral health is a major concern, especially with regards to prosthetic replacement of missing teeth.
• Dentures are a common solution, but they can lead to oral biofilms, mucosal infections, and denture stomatitis (DS).

Background

• DS is a common condition that affects denture wearers, causing chronic inflammation and erythema of the oral mucosa.
• The prevalence of DS ranges from 15% to over 70%, and it can cause symptoms such as pain, discomfort, and altered taste.
• Proper hygiene practices are essential in preventing DS, but patients' habits and attitudes may not lead to compliance with denture cleansing recommendations.
• Strategies employing acrylics with antimicrobial properties are being explored to prevent microorganism proliferation and reduce DS incidence.

Study Aim

• The study aimed to develop antimicrobial acrylic dentures by incorporating copper nanoparticles (nCu) into poly(methyl methacrylate) (PMMA).
• The goal was to produce dentures with antimicrobial activity, specifically against Candida albicans, without altering the biocompatibility, mechanical, or aesthetic properties of the acrylic.

Methods

• The nCu/PMMA nanocomposites were prepared using an in situ method, and their properties were characterized using various techniques, including scanning electron microscopy, spectroscopy, and X-ray diffraction analysis.
• The antimicrobial activity of the nanocomposites was evaluated against C. albicans, Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Staphylococcus aureus.
• A preliminary clinical trial was conducted on 50 patients, with 25 participants wearing nCu/PMMA dentures and 25 wearing conventional PMMA acrylic dentures.

Results

• The nCu/PMMA nanocomposites exhibited antimicrobial activity against C. albicans and other oral bacteria without producing cytotoxicity.
• The nanocomposites retained their mechanical and aesthetic properties and inhibited the growth of C. albicans on both the denture surface and patient palate.
• The incidence and severity of DS were lower in the nCu/PMMA denture group compared to the PMMA denture group.

Conclusion

• The study demonstrated that PMMA acrylic produced with copper nanotechnology is antimicrobial, biocompatible, and aesthetic, and can reduce DS incidence.
• The nCu/PMMA dentures may act as a novel preventive alternative for oral infections associated with denture use.### Denture Fabrication and Nanocomposite Properties
• The Beraudent Dental Laboratory in Santiago, Chile, fabricated both conventional and nCu/PMMA nanocomposite dentures.
• The nCu/PMMA nanocomposite dentures were fabricated using nanotechnology patented by the authors' university, with a copper concentration of 0.6% by weight.
• The nCu particles in the MMA monomer had a characteristic surface plasmon resonance absorption peak at 593 nm and a size range of 30-150 nm.

Structural and Compositional Characterization

• The BS-SEM image revealed metallic nCu embedded in the organic monomer as bright particles with sizes ranging from 30 to 150 nm.
• EDX elemental mapping confirmed the presence of copper, carbon, and oxygen in the structures of nCu and MMA.
• The XRD pattern of the PMMA polymer in both PMMA and Cu/PMMA acrylics showed an amorphous pattern.
• The XRD pattern of the Cu/PMMA matrix exhibited a peak at 2θ = 43.3°, corresponding to the (111) plane of zerovalent copper.

Antimicrobial Activity and Biocompatibility

• The nCu/PMMA nanocomposite displayed antifungal properties, with a maximum reduction in Candida albicans growth using 0.045% wt.nCu.
• The SEM images showed abundant C. albicans growth on the conventional PMMA acrylic surface, but near complete absence of yeasts on the surface of the 0.045% wt.nCu/PMMA nanocomposite.
• The viability of human gingival stem cells on the 0.045% wt.nCu/PMMA nanocomposite did not differ significantly from that of neat PMMA and control cells.

Copper Release and Mechanical Properties

• The copper release experiments showed that the 0.055% and 0.045% wt.nCu/PMMA nanocomposites produced maximum copper concentrations of 3.8 × 10^−3 and 5.9 × 10^−3 μg·mL^−1, respectively.
• The flexural strength and bending modulus of nCu/PMMA were not significantly different from those of PMMA.

Preliminary Clinical Trial

• The clinical trial involved 25 patients who completed the entire 12-month protocol: 12 patients who wore conventional PMMA dentures and 13 patients who wore the experimental 0.045% wt.nCu/PMMA dentures.
• The incidence of denture stomatitis (DS) was lower in the nCu/PMMA group than in the PMMA group at 7 and 12 months.
• The severity of DS among the participants was also lower in the nCu/PMMA group.