Evaluation of the Candida albicans removal and mechanical properties of denture acrylics cleaned by a low-cost powered toothbrush

Enamel Remineralisation with a Novel Sodium Fluoride-Infused Bristle Toothbrush

This study aims to investigate whether toothbrushes with fluoride-infused bristles have any (re)mineralisation effects on bovine enamel. Bovine incisors (N = 160) were extracted, and the buccal side of the crown was cut into dimensions of ~5 mm × 5 mm with a low-speed saw. These specimens were randomly allocated into four groups: half (80 teeth) were stored in demineralising solution (DM), and the other half were stored in deionised water (DW) for 96 h. Then, they were brushed with a force of 2.0 ± 0.1 N for five min with a manual toothbrush with either fluoride-infused (TF) or regular (TR) bristles. Microhardness (Vickers), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were used to investigate the surfaces of the bovine enamel specimens before and after brushing. Two-way ANOVA was used to analyse the hardness data, and the pairwise comparison method was used to analyse the Ca/P ratio, for each group at α = 0.05. The results show that brushing with either of these toothbrushes increased the Vickers microhardness on DM and DW enamel (p < 0.001), whereas hydroxyapatite was revealed in all groups by XRD. The DM samples showed a significant increase (p < 0.05) in the Ca/P ratios after brushing with TR and TF. Conversely, under DW conditions, these ratios decreased significantly after brushing. In terms of the F atomic%, TF increased significantly. SEM revealed mineral deposition in the DM groups after toothbrushing. To conclude, toothbrushing effectively induces the microhardness of sound and demineralised enamel, while fluoride-infused bristles might be able to retain fluoride on the enamel surface.

Surface Characterization, Antimicrobial Activity, and Biocompatibility of Autopolymerizing Acrylic Resins Coated with Reynoutria elliptica Extract

We conducted surface characterization to assess the biocompatibility and investigate the antimicrobial activity against oral pathogens in autopolymerizing acrylic resins, coated with light-curable coating resin, containing various concentrations of Reynoutria elliptica extract (0, 200, 400, and 600 µg/mL). The R. elliptica extract powder was prepared using a freeze-drying technique. Further, a goniometer and microhardness tester were used to determine the water contact angle, and Vickers hardness, respectively; color measurements were performed on the uncoated and coated acrylic resin disks. The polyphenol content of the extracts from the coated acrylic resin disk was analyzed using UV-VIS spectroscopy. The antimicrobial activity of the coated acrylic resin disk against Streptococcus mutans and Candida albicans was observed for 24 and 48 h by measuring the optical density using spectrophotometry. In addition, biocompatibility was confirmed by testing the cell viability according to ISO 10993-5. The water contact angle, Vickers hardness, and color change values of the coated acrylic resin disks were not significantly different from the control. Polyphenol was detected in all experimental groups, with no significant differences between the experimental groups. The experimental groups exhibited significant antimicrobial activity against S. mutans and C. albicans compared to the control group, after 48 h of incubation. The cell viability between the control and experimental groups was not significantly different. The proposed coating resin containing R. elliptica extract is applicable on dental acrylic resins, due to their antimicrobial properties and excellent biocompatibility, with no deterioration of surface characteristics.

A nanostructured anti-biofilm surface widens the efficacy against spindle-shaped and chain-forming rod-like bacteria

Current control of pathogenic bacteria at all biomaterial interfaces is poorly attuned to a broad range of disease-causing pathogens. Leading antimicrobial surface functionalization strategies with antimicrobial peptides (AMPs), defensins, have not shown their promised efficacy. One of the main problems is the lack of stability and swift clearance from the surface. Surface nanotopography bearing sharp protrusions is a non-chemical solution that is intrinsically stable and long-lasting. Previously, the geometrically ordered arrays of nanotipped spines repelled or rapidly ruptured bacteria that come into contact. The killing properties so far work on cocci and rod-like bacteria, but there is no validation of the efficacy of protrusional surfaces on pathogenic bacteria with different sizes and morphologies, thus broadening the utility of such surfaces to cover increasingly more disease entities. Here, we report a synthetic analogue of nanotipped spines with a pyramidal shape that show great effectiveness on species of bacteria with strongly contrasting shapes and sizes. To highlight this phenomenon in the field of dental applications where selective bacterial control is vital to the clinical success of biomaterial functions, we modified the poly(methyl)-methacrylate (PMMA) texture and tested it against Streptococcus mutans, Enterococcus faecalis, Porphyromonas gingivalis, and Fusobacterium nucleatum. These nanopyramids performed effectively at levels well above those of normal and roughened PMMA biomaterials for dentistry and a model material for general use in medicine and disease transmission in hospital environments.

Biological and Chemo-Physical Features of Denture Resins

In the dental field, the study of materials has always been the basis of the clinical practice. Over the years, with the evolution of materials, it has been possible to produce safe and predictable prosthetic devices, with ever better aesthetic features, biocompatibility and patient satisfaction. This review briefly analyzes the features of dental resin materials to underline the biological, microbiological and chemo-physical characteristics. The main aim of prosthodontics is to rehabilitate patients and therefore improve their quality of life. Dental resins are the main materials used for the production of dentures. Once solidified, these polymers have different mechanical or surface characteristics. The results of the literature on these characteristics were analyzed and some new brand dental resins, known as modern resin, were subsequently evaluated. The new materials are undoubtedly a step forward in the creation of dental prostheses, and also in all subsequent maintenance phases. This review shows how changing the chemical structure of the resins could have microbiological influences on the growth and management of the biofilm, and also physical influences in terms of its mechanical characteristics. The development of new materials is a constant goal in dentistry in order to obtain increasingly predictable rehabilitations.

Candida albicans aspects of binary titanium alloys for biomedical applications

Titanium and its alloys are widely used in biomedical devices, e.g. implants, due to its biocompatibility and osseointegration ability. In fact, fungal (Candida spp.) infection has been identified as one of the key reasons causing the failure of the device that is inevitable and impactful to the society. Thus, this study evaluated the surface morphology, surface chemical composition and Candida albicans adhesion on specimens of 16 binary Ti-alloys (∼5 wt% of any one of the alloy elements: Ag, Al, Au, Co, Cr, Cu, Fe, In, Mn, Mo, Nb, Pd, Pt, Sn, V and Zr) compared with cp-Ti, targeting to seek for the binary Ti-alloys which has the lowest C. albicans infection. Candida albicans cultures were grown on the specimens for 48 h, and colony forming units (CFUs) and real-time polymerase chain reaction (RT-PCR) were used to evaluate the biofilm formation ability. Scanning electron microscopy and confocal laser scanning microscopy confirmed the formation of C. albicans biofilm on all specimens' surfaces, such that CFU results showed Ti-Mo, Ti-Zr, Ti-Al and Ti-V have less C. albicans formed on the surfaces than cp-Ti. RT-PCR showed Ti-Zr and Ti-Cu have significantly higher C. albicans DNA concentrations than Ti-Al and Ti-V (P < 0.05), whereas Ti-Cu has even showed a statistically higher concentration than Ti-Au, Ti-Co, Ti-In and Ti-Pt (P < 0.05). This study confirmed that Ti-Mo, Ti-Zr, Ti-Al and Ti-V have lower the occurrence of C. albicans which might be clinically advantageous for medical devices, but Ti-Cu should be used in caution.

Safety and Design Aspects of Powered Toothbrush-A Narrative Review

The powered toothbrush has become a modern dental tool that is available in the supermarket. Indeed, the design of the powered toothbrush, e.g., mechanical and electrical, would affect not only the efficacy but also the safety of the products. This narrative review attempted to view the powered toothbrush from design, safety, and application points with respect to tufts, filaments, handles, mechanics, motions, and materials interactions from various available sources. Different brands and models of powered toothbrushes have their own designs that might affect the clinical outcome. The rotational design was advocated to be clinically more effective than the manual one, some modern models might be designed with vibrational or oscillation (or mixed) tufts head that might be useful in patients with specific needs, such as having xerostomia or for the elderly. To conclude, tuft retention design is important in the powered toothbrush as it contributes significantly to safety as the fallen off tufts, filaments and metal parts might cause injury. Tests revealing the retention force of brush head plates and brush head bristles will be significant references for consumers to determine which design of powered toothbrushes is relatively safer.

Effect of Terminalia catappa Linn. on Biofilms of Candida albicans and Candida glabrata and on Changes in Color and Roughness of Acrylic Resin

This study aimed to investigate the effect of the n-butanol fraction of Terminalia catappa Linn., (FBuTC) on biofilm of Candida albicans and Candida glabrata, as well as changes in color and roughness of polymethyl methacrylate resin (PMMA). The susceptibility of C. albicans and C. glabrata to FBuTC was evaluated by means of the Minimum Inhibitory and Minimum Fungicidal Concentration (MIC and MFC). PMMA acrylic resin discs (N= 108) were fabricated. For the susceptibility tests, biofilms of C. albicans and C. glabrata were developed on discs for 48 h and immersed in phosphate-saline buffer solution (PBS), 1% sodium hypochlorite (SH 1%), or FBuTC at MIC, 5xMIC, or 10xMIC. For the color and roughness change tests, the discs were immersed in distilled water, SH 1%, or FBuTC in the concentrations of 0.25 mg/mL, 2.5 mg/mL, or 25.0 mg/mL. After 28 days of incubation, color change was evaluated by spectrophotometry and roughness, by using a profilometer. The biofilms were investigated by one-way ANOVA and, the color and roughness changes (two-way ANOVA and the Tukey test; α=0.05). For both MIC and MFC the value of 0.25 mg/mL of FBuTC was observed for the planktonic cells of C. albicans and C. glabrata. Exposure to FBuTC at 10xMIC had a significant effect on the biofilm of C. albicans, showing a reduction in cell counts when compared with PBS, (p=0.001). For the biofilm of C. glabrata, the MIC was sufficient for significantly reducing the cell count (p<0.001). No important changes in color and roughness of the acrylic resin were observed, even after 28 days, irrespective of the concentration of FBuTC used (p >0.05). It could be concluded that the immersion of acrylic resin for dental prosthesis in FBuTC was effective in reducing the biofilms of C. albicans and C. glabrata without evidence of change in roughness and color of this substrate.

Superhydrophilic co-polymer coatings on denture surfaces reduce Candida albicans adhesion-An in vitro study

OBJECTIVE

In this study, we aimed to investigate denture-base-resin coatings prepared with a crosslinkable co-polymer containing sulfobetaine methacrylamide (SBMAm) and the relationship between their surface characteristics and the initial adhesion of Candida albicans (C. albicans).

METHODS

Acrylic resin discs were coated with co-polymers containing various concentrations of SBMAm and N,N'-(4,7,10-trioxa-1,13-tridecadiamine) diacrylamide (JDA) as crosslinking agent. Uncoated discs were used as controls. An acquired pellicle was formed on each disc using artificial saliva, and the discs were immersed in a suspension of C. albicans (JCM2085) cells. After incubation, tetrazolium salt (XTT-reduction) and colony forming unit (CFU) assays were performed and the morphogenesis of C. albicans was examined using scanning electron microscopy (SEM). The surface roughness, film thickness, and the water contact angle of each disc surface were measured.

RESULTS

All coating groups showed significantly lower amounts of adhered C. albicans in the XTT-reduction and CFU assays than the control, confirmed by the SEM images. Many wrinkle structures were observed on the surfaces coated with co-polymers containing more than 30% SBMAm. There were no significant differences in surface roughness among all groups. The co-polymer films on the coated discs were less than 5.0 μm in thickness, and these surfaces exhibited significantly lower mean water contact angles than the control.

CONCLUSION

Crosslinkable co-polymers containing SBMAm can enhance the hydrophilicity of the surface of denture-base resins and reduce the initial adhesion of C. albicans.

In vitro Effects of Lemongrass Extract on Candida albicans Biofilms, Human Cells Viability, and Denture Surface

The purpose of this study was to investigate whether immersion of a denture surface in lemongrass extract (LGE) has effects on C. albicans biofilms, human cell viability and denture surface. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were performed for LGE against C. albicans. For biofilm analysis, discs were fabricated using a denture acrylic resin with surface roughness standardization. C. albicans biofilms were developed on saliva-coated discs, and the effects of LGE at MIC, 5XMIC, and 10XMIC were investigated during biofilm formation and after biofilm maturation. Biofilms were investigated for cell counting, metabolic activity, and microscopic analysis. The cytotoxicity of different concentrations of LGE to peripheral blood mononuclear cells (PBMC) was analyzed using MTT. The effects of LGE on acrylic resin were verified by measuring changes in roughness, color and flexural strength after 28 days of immersion. Data were analyzed by ANOVA, followed by a Tukey test at a 5% significance level. The minimal concentration of LGE required to inhibit C. albicans growth was 0.625 mg/mL, while MFC was 2.5 mg/mL. The presence of LGE during biofilm development resulted in a reduction of cell counting (p < 0.05), which made the MIC sufficient to reduce approximately 90% of cells (p < 0.0001). The exposure of LGE after biofilm maturation also had a significant antifungal effect at all concentrations (p < 0.05). When compared to the control group, the exposure of PBMC to LGE at MIC resulted in similar viability (p > 0.05). There were no verified differences in color perception, roughness, or flexural strength after immersion in LGE at MIC compared to the control (p > 0.05). It could be concluded that immersion of the denture surface in LGE was effective in reducing C. albicans biofilms with no deleterious effects on acrylic properties at MIC. MIC was also an effective and safe concentration for use.

Reduction of Candida biofilm adhesion by incorporation of prereacted glass ionomer filler in denture base resin

OBJECTIVES

This study investigated the influence of surface reaction-type prereacted glass ionomer (S-PRG) fillers on Candida albicans adhesion on denture base resin.

METHODS

Discs were prepared by incorporating the S-PRG filler into the polymer powder of a polymethyl methacrylate (PMMA)-based, heat-polymerizing resin at 0 (control), 5%, 10%, and 20% (w/w). The surface roughness of all disc surfaces was measured. Elemental analysis of released Na(+), Sr(2+), SiO3(2-), Al(3-), BO3(3-), and F(-) was performed after water immersion. Each disc was placed in a well with artificial saliva to form acquired pellicle, incubated, washed with phosphate-buffered saline, and immersed in a C. albicans (JCM2085) cell suspension standardized at 10(4) cells/ml. After aerobic incubation at 37 °C for 24 h, the metabolic mitochondrial activity, total biofilm biomass, and biofilm thickness were evaluated. The morphogenetic transition of C. albicans in the early culture stage (1 and 3 h) was observed.

RESULTS

There was a slight but significant increase in the surface roughness with an increase in the filler content. The metabolic activity and total biomass volume were significantly lower in all filler groups than in the control group, although there were no significant differences among the filler groups. Groups with at least 5% filler content exhibited a thinner biofilm compared with the control group. All filler groups showed hyphal forms at 3 h, with the length of the hyphae being lesser than those in the control group.

CONCLUSIONS

Although the incorporation of S-PRG filler slightly increases the surface roughness of denture base resin, it reduces the adhesion of C. albicans.

CLINICAL SIGNIFICANCE

The S-PRG filler has the potential to reduce Candida albicans adhesion on denture base resin and may lower the risk of denture stomatitis. However, filler incorporation can increase the surface roughness of heat-polymerizing denture base resin.