Effect of Different Surface Treatments as Methods of Improving the Mechanical Properties after Repairs of PMMA for Dentures
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ABSTRACT:
SUBMITTER: Chladek G
PROVIDER: S-EPMC11242954 | biostudies-literature | 2024 Jul
REPOSITORIES: biostudies-literature
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Project description:Candida-associated denture stomatitis is a recurring disease affecting up to 67% of denture wearers. Poly(methyl methacrylate) (PMMA) remains the main material employed in the fabrication of dentures due to its desirable physical, mechanical, and aesthetic properties. However, the improvement of its antimicrobial properties remains a challenge. To address this need, we developed PMMA composite filled with piezoelectric nanoparticles of barium titanate (BaTiO3) for therapeutic effects. Candida albicans biofilms were cultivated on the surface of the composites under continuous cyclic mechanical loading to activate the piezoelectric charges and to resemble mastication patterns. The interactions between biofilms and biomaterials were evaluated by measuring the biofilm biomass, metabolic activity, and the number of viable cells. To explore the antifungal mechanisms, changes in the expression of genes encoding adhesins and superoxide dismutase were assessed using reverse transcription-polymerase chain reaction. With the addition of piezoelectric nanoparticles, we observed a significant reduction in the biofilm formation and interference in the yeast-to-hyphae transition compared to the standard PMMA. Moreover, we observed that the cyclic deformation of biomaterial surfaces without antifungal agents produced increased biomass, metabolic activity, and a number of viable cells compared to the static/no-deformed surfaces. Cyclic deformation appears to be a novel mechanobiological signal that enables pathogenicity and virulence of C. albicans cells with increased expression of the yeast-to-hyphae transition genes. The outcome of this study opens new opportunities for the design of antifungal dentures for improved clinical service and reduced need for cleaning methods.
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Project description:Background. Repairing aged composite resin is a challenging process. Many surface treatment options have been proposed to this end. This study evaluated the effect of different surface treatments on the shear bond strength (SBS) of nano-filled composite resin repairs. Methods. Seventy-five cylindrical specimens of a Filtek Z350XT composite resin were fabricated and stored in 37°C distilled water for 24 hours. After thermocycling, the specimens were divided into 5 groups according to the following surface treatments: no treatment (group 1); air abrasion with 50-μm aluminum oxide particles (group 2); irradiation with Er:YAG laser beams (group 3); roughening with coarse-grit diamond bur + 35% phosphoric acid (group 4); and etching with 9% hydrofluoric acid for 120 s (group 5). Another group of Filtek Z350XT composite resin samples (4×6 mm) was fabricated for the measurement of cohesive strength (group 6). A silane coupling agent and an adhesive system were applied after each surface treatment. The specimens were restored with the same composite resin and thermocycled again. A shearing force was applied to the interface in a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests (P < 0.05). Results. One-way ANOVA indicated significant differences between the groups (P < 0.05). SBS of controls was significantly lower than the other groups; differences between groups 2, 3, 4, 5 and 6 were not significant. Surface treatment with diamond bur + 35% phosphoric acid resulted in the highest bond strength. Conclusion. All the surface treatments used in this study improved the shear bond strength of nanofilled composite resin used.
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Project description:Even before considering their introduction into the mouth, the choice of materials for the optimization of the prosthesis depends on specific parameters such as their biocompatibility, solidity, resistance, and longevity. In the first part of this two-part review, we approach the various mechanical characteristics that affect this choice, which are closely related to the manufacturing process. Among the materials currently available, it is mainly polymers that are suitable for this use in this field. Historically, the most widely used polymer has been polymethyl methacrylate (PMMA), but more recently, polyamides (nylon) and polyether ether ketone (PEEK) have provided interesting advantages. The incorporation of certain molecules into these polymers will lead to modifications aimed at improving the mechanical properties of the prosthetic bases. In the second part of the review, the safety aspects of prostheses in the oral ecosystem (fragility of the undercuts of soft/hard tissues, neutral pH of saliva, and stability of the microbiota) are addressed. The microbial colonization of the prosthesis, in relation to the composition of the material used and its surface conditions (roughness, hydrophilicity), is of primary importance. Whatever the material and manufacturing process chosen, the coating or finishes dependent on the surface condition remain essential (polishing, non-stick coating) for limiting microbial colonization. The objective of this narrative review is to compile an inventory of the mechanical and physical properties as well as the clinical conditions likely to guide the choice between polymers for the base of removable prostheses.
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Project description:Poly(methylmethacrylate) (PMMA) is a widely used material in dental applications, particularly as denture resins. Due to thermally unstable and wet oral cavity, the implanted PMMA based resins occasionally deform and grow bacterial biofilms at the interface between oral cavity and the biomaterial. Several strategies attempted earlier to improve the bacterial resistance and mechanical performance of PMMA. Poly(ethyleneimine) (PEI) is a hyperbranched cationic polymer shown earlier to improve antibacterial activity of resins but do not improve mechanical properties of the resins alone, while silk fibroin (SF) is a natural biopolymer with unique material properties. In this study, we combined SF and PEI towards development of antibacterial and mechanically superior PMMA based materials towards overcoming its drawbacks. Using polyblend electrospinning to combine SF, PEI and PMMA, we successfully developed intrinsically antibacterial and mechanically reinforced nanofiber mats. We propose that the resulting nanofiber mats have the potential to be incorporated into PMMA based denture resin materials to overcome the problems of patients and improve their quality of life.
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Project description:PMMA-based cements are the most used bone cements in vertebroplasty and total hip arthroplasty. However, they present several drawbacks, including susceptibility to bacterial infection, monomer leakage toxicity, and high polymerization temperature, which can all lead to damage to the surrounding tissues and their failure. In the present study, silver nanowires (AgNWs) have been introduced to bestow antibacterial properties; chitosan (CS) to promote porosity and to reduce the polymerization temperature, without negatively affecting the mechanical performance; and methacryloyl chitosan (CSMCC) to promote cross-linking with methyl methacrylate (MMA) and reduce the quantity of monomer required for polymerization. Novel PMMA cements were formulated containing AgNWs (0 and 1% w/w) and CS or CSMCC at various concentrations (0, 10, 20, and 30% w/w), testing two different ratios of powder and MMA (P/L). Mechanical, thermal, antibacterial, and cytotoxic properties of the resulting composite cements were tested. Cements with concentrations of CS > 10% presented a significantly reduced polymerization temperature. The mechanical performances were affected for concentrations > 20% with a P/L concentration equal to 2:1. Concentrations of AgNWs as low as 1% w/w conferred antimicrobial activity against S. aureus, whereas biofilm formation on the surface of the cements was increased when CS was included in the preparation. The combination of CS and AgNWs allowed a higher concentration of Ag+ to be released over time with enhanced antimicrobial activity. Inclusion of AgNWs did not affect cell viability on the scaffolds. In conclusion, a combination of CS and AgNWs may be beneficial for reducing both polymerization temperature and biofilm formation, without significantly affecting mesenchymal stem cell proliferation on the scaffolds. No advantages have been noticed as a result of the reducing P/L ratio or using CSMCC instead of CS.
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