Denture Acrylic Surfaces Research Articles

Impact of Cigarette Smoke Condensate on Adhesion-Related Traits and Hemolysin Production of Oral Candida dubliniensis Isolates.

Cigarette smoke is associated with higher oral Candida carriage and possible predisposition and increased susceptibility to oral candidal infection. Candida dubliniensis is associated with oral candidosis. Candidal adherence to buccal epithelial cells (BEC) and denture acrylic surfaces (DAS), germ tube (GT) formation, cell surface hydrophobicity (CSH) and hemolysin production are pathogenic traits of Candida. The impact of exposure to cigarette smoke on the aforementioned pathogenic attributes of oral C. dubliniensis has not been studied. Hence, the impact of cigarette smoke condensate (CSC) on adhesion to BEC and DAS, GT formation, CSH and hemolysin production of 20 oral C. dubliniensis isolates after exposure to CSC for 24, 48 and 72h was ascertained. After preparation of the CSC, using an in-house smoking device, the Candida isolates were exposed to the CSC for 24, 48 and 72h, by a previously described in vitro method. Thereafter, the adhesion to BEC and DAS, GT formation, CSH and hemolysin production of C. dubliniensis isolates was investigated by hitherto described in vitro assays. Exposure to CSC significantly increased the ability of C. dubliniensis oral isolates to adhere to BEC, DAS, GT formation, CSH and produce hemolysin following 24-h, 48-h and 72-h exposure periods to CSC (P < 0.001 for all attributes tested). Exposure of oral C. dubliniensis isolates to CSC may significantly promote in vitro adhesion traits and hemolysin production of these isolates, thereby augmenting its pathogenicity in vitro in the presence of cigarette smoke.

In vitro Post-Antifungal Effect of Posaconazole and Its Impact on Adhesion-Related Traits and Hemolysin Production of Oral Candida dubliniensis Isolates

Objective: Candidal adherence to denture acrylic surfaces (DAS) and oral buccal epithelial cells (BEC), formation of candidal germ tubes (GT), candidal cell surface hydrophobicity (CSH), and hemolysin production are important pathogenic traits of Candida. The antifungal drug-induced post-antifungal effect (PAFE) also impacts the virulence of Candida. Candida dubliniensis isolates are associated with the causation of oral candidiasis which could be managed with posaconazole. Thus far there is no evidence on posaconazole-induced PAFE and its impact on adhesion-related attributes and production of hemolysin by C. dubliniensis isolates. Hence, the PAFE, adhesion to DAS and BEC, formation of GT, CSH, and hemolysin production of 20 oral C. dubliniensis isolates after brief exposure to posaconazole was ascertained. Materials and Methods: The PAFE, adherence to DAS and BEC, formation of GT, candidal CSH, and hemolysin production were investigated by hitherto described in vitro assays. Results: The mean PAFE (h) induced by posaconazole on C. dubliniensis isolates was 1.66. Exposure to posaconazole suppressed the ability of C. dubliniensis to adhere to DAS, BEC, formation of candidal GT, candidal CSH and to produce hemolysin by a reduction of 44, 33, 34, 36, and 15% (p < 0.005 to p < 0.001), respectively. Conclusion: Exposure of C. dubliniensis isolates to posaconazole for a brief period induced an antimycotic impact by subduing its growth in addition to suppressing pathogenic adherence-associated attributes, as well as production of hemolysin.

The effect of &lt;i&gt;Piper&lt;/i&gt; &lt;i&gt;betle&lt;/i&gt; against &lt;i&gt;Candida&lt;/i&gt; &lt;i&gt;albicans&lt;/i&gt; adherence to denture acrylic surfaces

Antimicrobial activity of medicinal plants has been identified since ancient times, and has been used to cure bacterial and fungal diseases. Piper betle is an important medicinal plant with its medicinal properties extending to antimicrobial activity against several pathogenic fungi and bacteria. The objective of this study was to evaluate the effect of P. betle leaf extract on Candida albicans adhesion on denture acrylics. Young betel leaves (1 st - 3 rd leaf) were subjected to vacuum infiltration with ethanol. Anticandidal activity of a range of concentrations of the leaf extract (5,000 – 10,000 ppm) was assessed against C. albicans (ATCC 90028) and seven laboratory isolates using the agar well bioassay. Further, the same concentrations were used to test their ability to suppress the adhesion of C. albicans on denture acrylics, as compared to a commercial denture cleanser (positive control), and sterile distilled water (negative control) using an adhesion assay. The results indicated that sterile distilled water had the highest adhesion (23.75 ±5.3 cells per unit area) while both, the leaf extract of concentrations of 8,000 – 10,000 ppm and the commercial denture cleanser showed significant (p C. albicans adhesion on denture acrylics. There was no significant difference between adhesion in an 8000 ppm concentration extract of P. betle and the commercial denture cleanser of equal concentration, indicating that betel leaf extract is as efficient as the commercial denture cleanser, in suppressing the adhesion of C. albicans on denture acrylic surfaces

Reducing the surface roughness of dental acrylic resins by using an eggshell abrasive material

Statement of problemExcessive surface roughness of denture base resins adversely impacts oral health. PurposeThe purpose of this in vitro study was to examine the abrasive potential of eggshell powder in reducing the surface roughness of denture base resins. Material and methodsThirty poly(methyl methacrylate) specimens were fabricated and polished with eggshell powders of different particle sizes and with pumice. The average surface roughness (Ra) after polishing was measured with a profilometer. Scanning electron microscope and optical electron microscope techniques were used to assess the surface roughness morphology of the specimens. ANOVA was used to analyze the Ra values. The Tukey honest significant differences and Bonferroni tests were used to identify differences between the 2 abrasive materials (α=.05). ResultsSignificant differences in the Ra values were observed between the fine and medium eggshell powder abrasives (P<.05). Similarly, significant differences were found between pumice and the fine eggshell powder abrasives (P<.001). No significant differences were found between pumice and the medium eggshell powder abrasive (P>.05). Specimens polished with pumice had the highest Ra values, whereas specimens polished with the fine eggshell powder abrasive had the lowest Ra values. ConclusionsBy connecting the Ra values to the threshold limit value of 0.2 μm, eggshell powder abrasive finished denture acrylic resin surfaces better than pumice.

In vitro Impact of Limited Exposure to Subtherapeutic Concentrations of Chlorhexidine Gluconate on the Adhesion-Associated Attributes of Oral Candida Species

Objective:Candida albicans and its non-albicans counterparts, such as C. tropicalis, C. krusei, C. glabrata and C. dubliniensis, are the major etiological agents of oral candidosis. Their adherence to buccal epithelial cells (BEC), denture acrylic surfaces (DAS) and cell surface hydrophobicity (CSH) are attributes associated with yeast colonization and infection. Chlorhexidine gluconate (CG) is a widely used antiseptic in dentistry. When administered, the diluent effect of saliva and the cleansing effect of the oral musculature reduce its bioavailability, compromising its efficacy. Hence, intraorally, Candida undergoes a transient exposure to high CG concentrations, and thereafter it is likely to be subtherapeutic. Therefore, the impact of CG on adhesion to BEC, DAS and CSH of different oral Candida species was investigated following brief exposure to three subtherapeutic concentrations of CG. Materials and Methods: Ten oral isolates of each of the above five Candida species obtained in Kuwait from oral rinse samples were exposed to 0.00125, 0.0025 and 0.005% CG for 30 min. Subsequently, the yeast adhesion to BEC, DAS and CSH was determined. The data were analyzed using ANOVA Dunnett's t tests. Results: Exposure to the lowest dilution (0.00125%) of CG did not elicit a noteworthy collective suppression on all three adhesion traits evaluated. Exposure to 0.0025% CG curtailed the adhesion to BEC, DAS and CSH of Candida species by 50.89, 40.79 and 24.58%, respectively (p < 0.001). Exposure to the highest concentration (0.005%) of CG reduced the adhesion to BEC, DAS and CSH of Candida species by 64.68, 54.59 and 50%, respectively (p < 0.001). Conclusions: Brief exposure to subtherapeutic concentrations of CG suppressed the adhesion to BEC, DAS and CSH of oral Candida species, indicating probable pharmacodynamics that may potentiate its antiseptic properties.

Caspofungin-induced in-vitro post-antifungal effect and its impact on adhesion related traits of oral Candida dubliniensis and Candida albicans isolates.

Adhesion to buccal epithelial cells (BEC) and denture acrylic surfaces (DAS), germ tube (GT) formation and cell surface hydrophobicity (CSH) are all virulence traits involved in the pathogenicity of Candida. Post-antifungal effect (PAFE) also have a bearing on pathogenicity and virulence of Candida. Candida dubliniensis is associated with oral and systemic candidosis, which can be managed with caspofungin. There is no published information on caspofungin-induced PAFE and its impact on adhesion traits of C. dubliniensis isolates. Thus, the purpose of this investigation was to determine the in vitro duration of PAFE on 20 C. dubliniensis isolates following transient exposure to caspofungin. Furthermore the impacts of caspofungin-induced PAFE on adhesion to BEC and DAS, GT formation and CSH of these isolates were also determined. After establishing the minimum inhibitory concentration (MIC) of caspofungin, C. dubliniensis isolates were exposed to sub-lethal concentrations (×3 MIC) of caspofungin for 1 hr. Thereafter the duration of PAFE, adhesion to BEC and DAS, GT formation and CSH were determined by previously described in-vitro assays. MIC (μg/mL) of C. dubliniensis isolates to caspofungin ranged from 0.004 to 0.19. Caspofungin-induced mean PAFE on C. dubliniensis isolates was 2.17 hr. Exposure to caspofungin suppressed the ability of C. dubliniensis isolates to adhere to BEC and DAS, form GT and CSH by 69.97%, 71.95%, 90.06% and 32.29% (P < 0.001 for all), respectively. Thus, transient exposure of C. dubliniensis isolates to caspofungin produces an antifungal effect not only by suppressing its growth but also by altering its adhesion traits.

Biofilm development by blastospores and hyphae of Candida albicans on abraded denture acrylic resin surfaces

Candida albicans is a known etiologic agent of denture stomatitis. Candida hyphae exhibit the ability to respond directionally to environmental stimuli. This characteristic is thought to be important in the penetration of substrata such as resilient denture liners and host epithelium. It has been suggested that hyphal production also enhances adhesion and survival of Candida on host and denture surfaces. Surface roughness, in addition, can enhance adhesion where stronger interactions occur between cells and surface features of similar dimensions. The purpose of this study was to assess the development of hyphal and blastospore biofilms on abraded denture acrylic resin specimens and measure the ease of removal of these biofilms. Biofilms were grown for 48 hours on abraded 1-cm² denture acrylic resin specimens from adhered hyphal phase C albicans or from adhered blastospores. Subsequently, all specimens were stained with Calcofluor White and examined with confocal scanning laser microscopy. Biofilms were removed by vortex mixing in sterile phosphate buffered saline solution. Removed cells were filtered (0.2-μm pore size). Filters were dried at 37°C for 24 hours for dry weight measurements. Any cells that remained on the acrylic resin specimens were stained with 0.03% acridine orange and examined with epifluorescence microscopy. Biofilms grown from both cell types contained all morphologic forms of C albicans. Although the underlying surface topography did not affect the amount of biofilm produced, biofilms grown from hyphal phase Candida were visibly thicker and had greater biomass (P<.05). These biofilms were less easily removed from the denture acrylic resin, especially in the case of rougher surfaces, evidenced by the higher numbers of retained cells (P≤.05). The presence of hyphae in early Candida biofilms increased biofilm mass and resistance to removal. Increased surface roughness enhances retention of hyphae and yeast cells, and, therefore, will facilitate plaque regrowth. Therefore, minimization of denture abrasion during cleaning is desirable.

Effect of Phyllanthus emblica Linn. on candida adhesion to oral epithelium and denture acrylic

Objective To investigate the effect of Phyllanthus emblica (P. emblica) Linn. ethanolic extract on the adhesion of Candida albicans (C. albicans) to human buccal epithelial cells (BECs) and denture acrylic surfaces. Methods Human BECs and transparent acrylic strips were pretreated with ethanolic extract solution of P. emblica fruits at concentration ranged from 18.7 to 300 mg/mL. After washing BECs and the strips were inoculated with three strains of C. albicans (ATCC 10281 and two clinical isolates) (10 7 cells/mL). Normal saline solution (NSS) and 0.2% chlorhexidine gluconate were used as negative and positive controls, respectively. BECs were harvested on 12 μm-polycarbonate filters (Millipore, USA). The membrane filters and the strips were stained with Gram stain. Adherent yeast cells on 100 randomly selected epithelial cells and 20 randomly selected fields on each strip were counted under microscope. The statistical significance was calculated by Kruskal-Wallis and Tukey tests at a significant level of P< 0.05. Results Significant lower numbers of all strains of yeasts adhering to BECs and acrylic strips were observed after exposure to 75–300 mg/mL of plant extract compared with NSS. Conclusions The present study demonstrates that P. emblica ethanolic extract interferes with the adhesion of C. albicans to BECs and denture acrylic surfaces in vitro.

The post-antifungal effect (PAFE) of amphotericin B, nystatin, ketoconazole and 5-fluorocytosine and its impact on the colonization traits ofCandida glabrata

The post-antifungal effect (PAFE) has been shown to affect Candida pathogenicity, but there is little information on either PAFE or its association with the colonization traits of Candida glabrata. The objective of this study was to determine, in vitro, the PAFE on 14 C. glabrata isolates following exposure to amphotericin B (AMB), nystatin (NYS), ketoconazole (KETO) and 5-fluorocytosine (5FC). In addition, we evaluated the impact of PAFE on yeast adherence to buccal epithelial cells (BEC), cell-surface-hydrophobicity (CSH) and biofilm growth (BG) on denture acrylic surfaces. PAFE was induced following a 1-h exposure of yeasts to (x1-x4MIC) of AMB, NYS, KETO and 5FC in RPMI medium and, measured using automated turbidometry. The BEC adhesion, CSH and BG assays were performed by the methods of Kimura & Pearsall, Sweet et al., and Jin et al., respectively. Significant differences in PAFE (P < 0.001) were observed after exposure to AMB and NYS, but not KETO and 5FC. Following exposure to AMB, NYS, KETO and 5FC, significant inter-strain differences (P < 0.001) were observed in percentage terms in adhesion (39.0%, 43.48%, 38.28%, 35.07%) and biofilm growth (42.86%, 39.86%, 42.81%, 36.38%), respectively. Short exposure of C. glabrata to sub-cidal concentrations of antifungals modulates yeast growth and also affects some of their colonization traits.

Synergistic activity of lysozyme and antifungal agents against Candida albicans biofilms on denture acrylic surfaces

Denture related oral candidiasis is a recalcitrant fungal infection not easily resolved by topical antifungals. The antimycotic protein lysozyme, in saliva is an important host defense mechanism although its activity against Candida biofilms on denture acrylic has not been evaluated. Objectives (i) To establish a clinically relevant denture acrylic assay model to develop standardized Candida albicans biofilms, and (ii) assess the inhibitory effects of lysozyme alone and, the latter combined with antifungals (nystatin, amphotericin B, ketoconazole and 5-fluorocytosine) on sessile Candida cells and, finally (iii) to visualize the accompanying ultrastructural changes. Design The rotating-disc biofilm reactor was used to develop standardized 48 h Candida biofilms on acrylic discs in YNB/100 mM glucose medium and the biofilm metabolic activity was monitored using a tetrazolium reduction assay. Results The biofilm metabolic activity was similar in 18 identical denture acrylic discs ( p < 0.05) thus validating the rotating-disc biofilm model. Very low concentrations of lysozyme (6.25 μg/ml) significantly ( p < 0.01) inhibited Candida biofilm formation indicating that lysozyme may likely regulate intra-oral Candida biofilm development. Although 100 μg/ml lysozyme killed 45% of sessile Candida cells, further increasing its concentration (up to 240 μg/ml) had no such effect. Nystatin, amphotericin B, and ketoconazole in association with 100 μg/ml lysozyme exhibited effective synergistic killing of biofilm Candida in comparison to drug-free controls. Scanning electron and confocal scanning laser microscopy analysis confirmed the latter trends. Conclusion Our results indicate that agents found in biological fluids such as lysozyme could be a safe adjunct to antifungals in future treatment strategies for recalcitrant candidal infections.

Characteristics of dual species Candida biofilms on denture acrylic surfaces

Biofilms contribute to the pathogenesis of oral candidiasis, some 15% of which may be due to dual Candida species. Despite extensive studies on monospecies biofilms (MSB) on denture acrylic surfaces, few have investigated the characteristics of dual species Candida biofilms (DSB). Objectives To examine interactions of DSB of Candida albicans and Candida krusei on denture acrylic surfaces. Methods Two isolates each of C. albicans (Ca) and C. krusei (Ck), with high (Ca h, Ck h) and low (Ca l, Ck l) biofilm-forming ability were used. The biofilms were developed on acrylic surfaces aerobically at 37 °C in yeast nitrogen base (YNB) medium, and growth quantified by colony-forming unit (CFU) assay. We determined: (i) the population profiles of DSB comprising each pair of Candida species, of a total of four combination pairs, after 12 h, (ii) the effect of a constant concentration of Ca h (10 7 cells/ml) on varying concentrations of Ck h (10 3–10 7 cells/ml) on DSB development and (iii) the effect of saliva on the growth of DSB. Results (i) DSB exhibited a lower cell population after 9 or 12 h in comparison to MSB ( P < 0.05), (ii) C. albicans (10 7 cells/ml) co-cultured with varying initial concentrations of C. krusei was inhibited at high concentrations of the latter (10 6–10 7 cells/ml) ( P < 0.05) and (iii) only the MSB development of C. krusei was affected by saliva ( P < 0.05). Conclusion Our data suggest that the competitive interactions of fungal species are likely to be important in biofilm formation on acrylic surfaces and human saliva may further modulate this process.

Adhesion of Candida parapsilosis to epithelial and acrylic surfaces correlates with cell surface hydrophobicity.

We investigated in vitro adherence of 24 isolates of Candida parapsilosis and 12 isolates of Candida albicans with regard to their relative cell-surface hydrophobicity (CSH), adherence to human buccal epithelial cells (BEC) and acrylic surfaces. There was no significant interspecies difference in the relative adherence of C. parapsilosis and C. albicans isolates to BEC, although the former demonstrated a tendency for increased adherence. However, a significant intra-species variation in adherence among isolates of C. parapsilosis (P < 0.0001) to BEC, but not of C. albicans was noted. The superficial isolates of C. parapsilosis demonstrated a higher avidity (33%) to BEC than the systemic isolates. On regression analysis a significant positive correlation between C. parapsilosis adherence to BEC and denture acrylic surfaces was noted (r = 0.45, P = 0.02). Similarly, buccal cell adherence correlated strongly with CSH of C. parapsilosis (r = 0.63, P = 0.0008). These results shed further light on the intimate relationship between adherence and CSH in candidal colonization and imply that both C. parapsilosis and C. albicans are equally potent in colonizing mucosal surfaces with respect to the attributes investigated.

Exposure to Subtherapeutic Concentrations of Polyene Antifungals Suppresses the Adherence of Candida Species to Denture Acrylic

Background: The adherence of Candida species to denture acrylic is the initial event leading to Candida-associated denture stomatitis, with Candida albicans being the main aetiological agent. However, the increased incidence of immunocompromised patients in the community has resulted in the emergence of a number of non-albicans Candida species as causative agents of this disease, which is commonly managed by topically delivered polyene antifungals. Hence, we investigated the effect of the exposure of denture acrylic surfaces to nystatin and amphotericin B on the subsequent adhesion of six different Candida species. Methods: Acrylic strips were exposed to subtherapeutic concentrations of the two polyenes for 30 min, and the adhesion of 4 isolates each of C. albicans, Candida glabrata, Candida guilliermondii, Candida krusei, Candida parapsilosis and Candida tropicalis was assessed using a previously described in vitro method with slight modifications. Results: Overall, the results indicated a 35.9% (p < 0.01) and 63.1% (p < 0.01) reduction, respectively, in yeast adhesion to denture acrylic following exposure to nystatin and amphotericin B, although this effect was not uniform for all the tested isolates. Thus, all C. glabrata, 3 C. guilliermondii and a single isolate each of C. krusei, C. parapsilosis and C. tropicalis were not significantly affected by nystatin exposure, and a single isolate each of C. glabrata and C. guilliermondii were not significantly affected by amphotericin B. Conclusions: The present data, the first on the effect of polyenes on a wide range of Candida species, indicate that the in vitro exposure of denture acrylic to subtherapeutic concentrations of nystatin and amphotericin B suppresses the adherence of pathogenic Candida species in general.

The Role of Saliva and Serum inCandida albicansBiofllm Formation on Denture Acrylic Surfaces

The long term effect of either a salivary or a serum pellicle on Candida albicans biofilm formation on denture acrylic surfaces was investigated both by quantifying the ATP (adenosine triphosphate) content of the resultant biofilms and by scanning electron microscopy. When the biofilm formation on saliva-coated acrylic strips was examined, the yeasts initially colonised this surface at a slower rate than the controls although with increasing incubation time, at 72 h, the ATP content was almost ten-fold higher than the protein-free control strips. Ultrastructural studies revealed this to be due to cell aggregation and hyphal emergence, phenomena not observed in the controls. As compared with the control strips, biofilm activity of the serum-coated strips was almost 100-fold greater within 48 h incubation, and scanning electron microscopy revealed multilayer blastospore-blastospore co-adhesion, germ tube, hyphal and pseudohyphal emergence and blastospore-hyphal coadherence. Further immunocytochemical observation revealed that concanavalin-A binding material and fibronectin were involved in biofilm formation on both saliva and serum coated specimens and, in addition, mannan-binding protein and protein-A binding material also contributed to the biofilm formation on serum coated specimens. Keywords: Candida albicans , biofilm, saliva, serum, fibronectin, mannan-binding protein.

The Role of Saliva and Serum inCandida albicansBiofllm Formation on Denture Acrylic Surfaces

The Role of Saliva and Serum in<i>Candida albicans</i>Biofllm Formation on Denture Acrylic Surfaces

The Role of Saliva and Serum in Candida albicans Biofilm Formation on Denture Acrylic Surfaces

The Role of Saliva and Serum in Candida albicans Biofilm Formation on Denture Acrylic Surfaces

Relationship between the cell surface hydrophobicity and adherence of Candida krusei and Candida albicans to epithelial and denture acrylic surfaces

C. krusei is an emerging pathogen, especially in immunocompromised hosts, and is implicated, together with Candida albicans, as an etiological agent of oral candidoses. As the cell surface hydrophobicity of these yeasts appears to be important in the pathogenesis of superficial candidoses, 20 oral isolates of C. krusei and 5 oral isolates of C. albicans were investigated using a biphasic (hydrocarbon/aqueous) separation hydrophobicity assay. All the C. krusei isolates demonstrated significantly greater hydrophobicity than the C. albicans isolates (p < 0.001). Further, there were significant intraspecies differences in cell surface hydrophobicity amongst C. krusei isolates. When hydrophobicity and adhesion to surfaces were compared using data from a previous study, there was a positive correlation between the cell surface hydrophobicity and adhesion of C. krusei isolates to HeLa surfaces (r = 0.53, p < 0.05), but not to acrylic surfaces. The current data, while confirming the inter- and intraspecies differences in cell surface hydrophobicity of Candida species, indicate that this attribute together with other cell surface features may determine the hierarchy of virulence amongst the different Candida species.