Acrylic Denture Surfaces Research Articles

In vitro efficacy of synthetic lawsone derivative disinfectant solution on removing dual-species biofilms and effect on acrylic denture surface properties

Candida albicans (C. albicans) and Streptococcus mutans (S. mutans) biofilms involve in denture stomatitis. This study compared compound 1 to 2% chlorhexidine gluconate (CHX), Polident, and distilled water (DW) in biofilms reduction and effect on polymethylmethacrylate acrylic (PMMA) properties. The structure of lawsone (naphthoquinone derivative) was modified by the addition of an alkylnyloxy group to yield compound 1. Dual-species biofilms of C. albicans and S. mutans were developed on PMMA discs. The colony-forming unit count measured the number of residual biofilm cells after exposure to the test agents. PMMA discs were examined for color stability, surface roughness, hardness, and chemical structure after 28 days. At 3 min, compound 1 was less effective than CHX in reducing C. albicans (p = 0.004) and S. mutans (p = 0.034) but more effective than Polident in reducing C. albicans (p = 0.001). At 15 min, no viable cells were detectable for compound 1 and its effectiveness was comparable to CHX (p = 0.365). SEM showed fungal cell surface damages in CHX, compound 1 and Polident groups. Only color change was affected by time (p < 0.001) and type of test agent (p = 0.008), and only CHX reached a clinical perception level. Compound 1 is a promising agent for removing biofilm from the PMMA surface without substantially degrading surface properties.

Effect of EVA-TiO2 composite interfacial buffer layer in improving the bond strength between PMMA denture base and PDMS liner

Polydimethylsiloxane (PDMS) is the most common dental liner that is used with acrylic dentures. A strong bond between the liner and the denture is a must, for the proper functioning and the longevity of the prosthesis. Debonding of the liner may occur due to an inefficient bond with the denture, or low cohesive strength due to wettablility/hydration and water/liquid storage-retention. The increased wettability/hydration pass on the moisture to the acrylic boundary surface causing initiation of debonding process. Hence, in order to prevent the debonding due to wettablility/hydration a novel method of introducing a hydrophobic polymer interfacial buffer layer between the acrylic denture surface and the PDMS liner surface is suggested. In, the present research work, ethylene vinylacetate (EVA) reinforced with titania (TiO2) polymer microfilm composite layer is prepared by solution casting method. The thin polymer film is placed between the acrylic denture surface and the PDMS liner surface and heat cured together to obtain a hydrophobic interfacial buffer layer. Wettability, fluid absorption and retention tests were performed to investigate the hydrophobic properties of the composite interfacial buffer layer. Mechanical strength properties on the prepared specimen (as per ISO 178) revealed that the EVA-TiO2 layer offered superior bonding and also improved the overall mechanical properties of the acrylic dentures without disturbing the mass and density of the denture.

Interaction of Candida Albicans and Streptococcus Mutans with four different types of acrylic resin denture base materials Part (2)

For denture base materials to be clinically accepted, they have to meet certain requirements such as superior mechanical and chemical properties, having a natural appearance, being easy to construct, easy to repair as well as biocompatibility and resistance to adhesion of microorganisms. Microbial adhesion to denture base materials may lead to oral diseases such as candidiasis. The present in-vitro study was aimed to assess the adherence of Candida albicans and Streptococcus mutans to four different types of acrylic dentures; Heat Cure (HC), High Impact Heat Cure (HIHC), Heat Cure Clear (HCC) and Clear Chemical Cure (CC).&#x0D; Materials and Methods: 25 discs measuring 11 mm in diameter and 3 mm in thickness were fabricated for each type of acrylic resin. All samples were polished with different roughness parameters, including 600 and 1200 surface polishers. Candida albicans was cultured in Sabouraud dextrose broth (Sigma-Aldrich) while, S. mutans was cultured in a Columbia blood agar. They were then placed in an aerobic or CO2 incubator for Candida albicans and Streptococcus mutans respectively at 37ºC overnight. The absorbance of the crystal violet stain in the de-staining solution was measured. Subsequently, the samples were removed, fixed on a glass slide, and lastly viewed under the light microscope [Nikon (ECLIPS TS100)] at magnification 40x.&#x0D; Results: The highest average absorbance of C. albicans was shown in HCC600 and HC1200. Whereas, there was no significant difference in the P-value of C. albicans growth on the different surfaces of acrylic resins. Regarding the adhesion of Streptococcus mutants, CC had much more average absorbance than the other three heat cure types. When these materials were compared by ANOVA single factor, the data statistically showed a significant difference in the capacity of attachment between heat cure and chemical cure.&#x0D; Conclusion: The acrylic denture surface roughness by its nature has a large impact on the colonization of denture base, specifically by Streptococcus mutants.

Mechanical and antimicrobial effects of riboflavin-mediated photosensitization of in vitro C. albicans formed on polymethyl methacrylate resin

PurposeThis study assessed the potential of riboflavin-mediated photodynamic therapy (RF-PDT) against Candida albicans (C. albicans) and compared the effects of RF-PDT with other therapeutic modalities in terms of mechanical and surface characteristics of acrylic denture base material. Materials and methodsMolds (10 × 10 × 2 mm) of acrylic resin specimens were prepared and underwent artificial ageing. C. albicans were grown aerobically over the specimens and divided into four groups (n = 10/group); Group-I: no decontamination; Group-II: nystatin suspension; Group-III: riboflavin 0.1% in darkness, Group-IV: blue LED light only, and Group-V: riboflavin 0.1% for 10 minutes (pre-irradiation time) and photoactivated by the blue LED light (light dose). Fungal viability was assessed using MTT assay and characterized using scanning electron microscopy and confocal laser microscopy (CLSM). Treated specimens were subjected to surface roughness (Ra), flexural strength (FS), and flexural modulus (FM). ResultsGroup-I showed the highest C. albicans viability followed by Group-III. Nystatin group (Group-II) showed ∼50% of the viability while RF-PDT showed the least C. albicans viability among the four groups (p<0.05). On SEM, specimens treated with Group-IV and V showed almost clear and free from C. albicans that was evidenced on CLSM. Post-treated specimens and storage after 72 h revealed that FS was significantly higher for RF-PDT group as compared to any other group (>105.82 MPa) (p<0.05). The FM and Ra showed statistically no significant difference between the groups (p>0.05). ConclusionRF-PDT showed the highest anti-fungal capacity against C. albicans over acrylic denture surface without any surface deterioration.

Efficacy of red betel leaf (Piper crocatum) against Candida albicans over acrylic denture surface: An in vitro study

Aims and Objectives: The aim of this article is to assess the efficacy of red betel leaf against Candida albicans over acrylic denture surface. Materials and Methods: This research used an experimental design. The efficacy of red betel leaf was assessed through minimum inhibitory concentration (MIC) and immersion tests. The results of MIC test using microdilution method were determined using turbidimetric and spectrophotometric methods. The immersion test used 30 sterilized identical heat-cured acrylic resin plates (10×10×2 mm), five each for six groups contaminated by Candida albicans and immersed in different denture cleansers (red betel leaf extract with concentrations of 10%, 20%, 30%, and 40%, alkaline peroxide denture cleanser “fitty dent”® as positive control, and sterile distilled water as negative control). The number of microorganisms was calculated and analyzed using analysis of variance followed by post hoc test. Results: MIC of red betel leaf extract was 2.34% (turbidimetric method) and 0.29% (spectrophotometric method). The immersion test showed that the statistical analysis of the six groups was significant (P<0.01). The more the concentration of red betel leaf extracts (10%, 20%, 30%, and 40%), the lesser the number of colonies of C. albicans (48, 8.6, 4.4, and 4.2 ×103 CFU/mL); meanwhile, the reduction value increased to 62.09%, 93.21%, 96.53%, and 96.68%. There were no significant differences between 30% and 40% red betel leaf extract concentration (P = 0.89). The highest number of colonies was in negative control (126.6 × 103 CFU/mL) and the smallest was in positive control (1.3×103 CFU/mL). Conclusion: Red betel leaf had efficacy against C. albicans over acrylic denture surface at 30% concentration.

Anti-biofilm Action of Chenopodium ambrosioides Extract, Cytotoxic Potential and Effects on Acrylic Denture Surface.

Considering the challenge to control Candida-associated denture stomatitis, the search for antifungal substances derived from natural sources has become a trend in the literature. In this study the following effects of Chenopodium ambrosioides extract (CAE) were investigated: action against biofilms of Candida albicans, its cytotoxic potential, and changes caused in acrylic resin. The CAE was characterized by High Performance Liquid Chromatography (HPLC). The susceptibility of C. albicans to CAE was investigated by Minimum Inhibitory Concentration and Minimum Fungicidal Concentration (MIC and MFC) tests. Acrylic resin disks were fabricated, and C. albicans biofilms were developed on these for 48 h. Afterward the disks were immersed for 10 min in: PBS (Negative Control); 1% Sodium Hypochlorite (1% SH, Positive Control) or CAE at MIC or 5xMIC. The biofilms were investigated relative to counts and metabolic activity. The cytotoxic potential in keratinocytes and fibroblasts was verified by MTT test. Change in color and roughness of the acrylic resin was analyzed after 28 days of immersion in CAE. The data were analyzed by the ANOVA considering a 5% level of significance. The main compounds detected by HPLC were kaempferol and quercetin. Both MIC and MFC obtained the value of 0.25 mg/mL. The MIC was sufficient to significantly reduce the counts and activity of the biofilm cells (p < 0.0001), while 5xMIC resulted in almost complete eradication, similar to 1% SH. Keratinocytes and fibroblasts exposed to the MIC and 5xMIC presented cell viability similar to that of the Control Group (p > 0.05). No important changes in acrylic resin color and roughness were detected, even after 28 days. It could be concluded that the immersion of acrylic resin in C. ambrosioides extract in its minimum inhibitory concentration was effective for the reduction of C. albicans biofilms without any evidence of cytotoxic effects or changes in roughness and color of this substrate.

In vitro Adhesion of Oral Candida dubliniensis Isolates to Acrylic Denture Surfaces following Brief Exposure to Sub-Cidal Concentrations of Polyenes, Azoles and Chlorhexidine

Objectives: We aimed to investigate the effect of brief exposure to sub-cidal concentrations of nystatin, amphotericin B, ketoconazole, fluconazole and chlorhexidine gluconate on the adhesion of oral Candida dubliniensis isolates to the surface of acrylic dentures. Methods: After determining the minimum inhibitory concentration of each drug, 20 oral isolates of C. dubliniensis were exposed to sub-cidal concentrations of the drugs for 1 h. The drugs were then removed by dilution, and the adhesion of the isolates to denture acrylic strips was assessed by an in vitro adhesion assay. Results: Compared to the controls, exposure to nystatin, amphotericin B, ketoconazole, fluconazole and chlorhexidine gluconate suppressed the ability of C. dubliniensis isolates to adhere to acrylic denture surfaces with a reduction of 74.68, 74.27, 57.31, 44.57 and 56.53% (p < 0.001 for all drugs), respectively. Conclusions: Brief exposure to sub-cidal concentrations of anti-mycotics suppressed the adhesion of C. dubliniensis oral isolates to acrylic denture surfaces.

Inhibitory effect of coated mannan against the adhesion of Candida biofilms to denture base resin

The adherence of Candida on dentures is related to diseases such as denture stomatitis and aspiration pneumonia. Mannan is a major component of the Candida cell surface, and contributes to the cell adherence. A previous report indicated that the adherence of C. albicans to culture dishes was inhibited by the coating them with mannan. The purpose of this study was to examine the adhesion inhibitory effect of mannan coating on acrylic denture surfaces against C. albicans and C. glabrata. The amount of Candida attached on the acrylic surfaces coated with mannan was calibrated by culture methods. Mannan showed significant inhibitory effects on Candida adhesion in both the yeast and hyphal form in a concentration-dependent manner, and the durability of the inhibitory effect continued for three days. These results suggest that mannan coating on the denture base acrylic can prevent Candida adhesion on the denture.

In vitro study of biofilm formation and effectiveness of antimicrobial treatment on various dental material surfaces

Elevated proportions of Candida albicans in biofilms formed on dentures are associated with stomatitis whereas Streptococcus mutans accumulation on restorative materials can cause secondary caries. Candida albicans, S. mutans, saliva-derived and C. albicans/saliva-derived mixed biofilms were grown on different materials including acrylic denture, porcelain, hydroxyapatite (HA), and polystyrene. The resulting biomass was analysed by three-dimensional image quantification and assessment of colony-forming units. The efficacy of biofilm treatment with a dissolved denture cleansing tablet (Polident(®)) was also evaluated by colony counting. Biofilms formed on HA exhibited the most striking differences in biomass accumulation: biofilms comprising salivary bacteria accrued the highest total biomass whereas C. albicans biofilm formation was greatly reduced on the HA surface compared with other materials, including the acrylic denture surface. These results substantiate clinical findings that acrylic dentures can comprise a reservoir for C. albicans, which renders patients more susceptible to C. albicans infections and stomatitis. Additionally, treatment efficacy of the same type of biofilms varied significantly depending on the surface. Although single-species biofilms formed on polystyrene surfaces exhibited the highest susceptibility to the treatment, the most surviving cells were recovered from HA surfaces for all types of biofilms tested. This study demonstrates that the nature of a surface influences biofilm characteristics including biomass accumulation and susceptibility to antimicrobial treatments. Such treatments should therefore be evaluated on the surfaces colonized by the target pathogen(s).

In vitro candidacidal activity of a synthetic killer decapeptide (KP) against Candida albicans cells adhered to resin acrylic discs

Oral Candida spp., and C. albicans in particular, are considered as important aetiological agents in the pathogenesis of denture-induced stomatitis. Several studies have reported that C. albicans is able to easily adhere to different medical devices, such as vascular and urinary catheters or acrylic denture surfaces, and that adhesion is a fundamental step in the initial pathogenic process of colonization and further possible infection. Recently, a synthetic decapeptide (KP) derived from the sequence of a single-chain recombinant anti-idiotypic antibody, acting as a functional internal image of a microbicidal, broad spectrum yeast killer toxin, has been reported to kill in vitro C. albicans cells and to exert a therapeutic activity against experimental mucosal and systemic candidiasis. The aim of this study was to evaluate, through a CFU assay, the candidacidal activity of KP on sanded acrylic resin discs, previously colonized by C. albicans cells. At 100 microg/ml KP showed over 90% of killing activity on C. albicans cells adhered to resin discs, when compared with a scramble peptide used as control. The results of this study suggest a potential effect of KP on C. albicans cells adhered on the surface of resin materials, such as prosthetic dentures.