The denture microbiome in health and disease: an exploration of a unique community.

The United Nations suggests the global population of denture wearers (an artificial device that acts as a replacement for teeth) is likely to rise significantly by the year 2050. Dentures become colonized by microbial biofilms, the composition of which is influenced by complex factors such as patient's age and health, and the nature of the denture material. Since colonization (and subsequent biofilm formation) by some micro-organisms can significantly impact the health of the denture wearer, the study of denture microbiology has long been of interest to researchers. The specific local and systemic health risks of denture plaque are different from those of dental plaque, particularly with respect to the presence of the opportunist pathogen Candida albicans and various other nonoral opportunists. Here, we reflect on advancements in our understanding of the relationship between micro-organisms, dentures, and the host, and highlight how our growing knowledge of the microbiome, biofilms, and novel antimicrobial technologies may better inform diagnosis, treatment, and prevention of denture-associated infections, thereby enhancing the quality and longevity of denture wearers.

Does microwave and hydrogen peroxide disinfection reduce Candida albicans biofilm on polymethyl methacrylate denture surfaces?

STATEMENT OF PROBLEM: Whether the disinfection of polymethyl methacrylate (PMMA) dentures eliminates Candida albicans biofilm is unclear. PURPOSE: The purpose of this in vitro study was to determine the antimicrobial effect of immersion in hydrogen peroxide (H2O2) and subsequent application of microwaves on the formation of C albicans biofilm on the surface of polished and unpolished PMMA disks. MATERIAL AND METHODS: Polished and unpolished PMMA disks (n=40) were mounted in a Center for Disease Control (CDC) biofilm reactor by adding yeast-dextrose-peptone (YPD) broth inoculated with C albicans in a cell suspension for 24 hours. After this period, the PMMA disks (n=8) were disinfected with 5 different solutions: saline solution, 1% sodium hypochlorite (NaOCl), H2O2, H2O2 microwaved at 650 W for 3 minutes (H2O2/µw), and distilled water microwaved at 650 W for 3 minutes (H2O/µw). On the polished and unpolished surface of each disk, arbitrary fluorescence units (AFU) were quantified with the live/dead bacterial viability kit (Invitrogen) by using confocal laser scanning microscopy (CLSM) to evaluate 10 different areas of each surface; these were counted as the colony-forming units (CFUs). The mean values were compared by using the Mann-Whitney U test (α=.05). RESULTS: Polished surfaces disinfected with H2O2/µw obtained the lowest viable cells (9.76 AFU) and nonviable cells (12.46 AFU) compared with H2O/µw and H2O2. In the unpolished surface the lowest mean values of viable cells (14.64 AFU) and nonviable cells (12.46 AFU) were obtained for the PMMA disks disinfected with H2O/µw compared with H2O2/µw and H2O2. Both polished and unpolished disks showed significant difference (P<.05) compared with the group of PMMA disks immersed in saline solution. No CFUs were detected in the polished or unpolished PMMA disks immersed in H2O2/µw or in NaOCl. CONCLUSIONS: H2O2 alone did not eliminate the formation of the biofilm of C albicans; however, in combination with the use of the microwave at 650 W for 3 minutes, the biofilm formation of C albicans on polished surfaces was reduced. The number of AFUs of viable-nonviable cells and CFUs depended on whether the surfaces are polished or unpolished.

Digital Design of a Universal Rat Intraoral Device for Therapeutic Evaluation of a Topical Formulation against Candida-Associated Denture Stomatitis.

Candida-associated denture stomatitis (DS) is a persistent and chronic oral infection of the denture-bearing palatal mucosa. DS stems from the ability of the fungal opportunistic pathogen Candida albicans to adhere to denture material and invade palatal tissue. Although DS is the most prevalent form of oral candidiasis, there are currently no feasible therapeutic strategies for the prevention of this recurrent condition. We developed a peptide-based antimicrobial bioadhesive formulation specifically designed for oral topical formulation. In this study, we aimed to evaluate the applicability of the novel formulation for the prevention of C. albicans colonization on denture material and development of clinical disease. To that end, using the latest technological advances in dental digital design and three-dimensional (3D) printing, we fabricated an intraoral device for rats with universal fit. The device was successfully installed and used to develop clinical DS. Importantly, by taking a preventative therapeutic approach, we demonstrated the potential clinical utility of the novel formulation as a safe and feasible prophylactic agent against DS.

Pathogenic characteristics of Candida albicans isolated from oral cavities of denture wearers and cancer patients wearing oral prostheses.

Candida albicans cause opportunistic infections including oral candidiasis in immunocompromised patients. It has an ability to cause infection due to its virulence factors. This study investigated the pathogenic characteristics of C. albicans isolated from the oral cavities of healthy subjects and two vulnerable groups, denture wearers and cancer patients wearing oral prostheses. Oral rinse samples were collected and cultured for the quantitative and qualitative analysis of Candida. Twenty strains of C. albicans isolated from the healthy individuals and denture wearers and, 14 strains isolated from the cancer patients were selected and their pathogenic characteristics were measured. The results of the study groups were compared using a Scheffe test for pairwise comparison and a chi square test. Denture wearer and cancer patients with prostheses carried significantly higher number (p < 0.01) and a variety of Candida than the normal individuals. Denture wearer and cancer patients carried several Candida species. The adherence abilities (p = 0.01) as well as phospholipase (p < 0.01) and proteinase (p = 0.03) production were significantly higher in the strains from denture wearers. In addition, high number of isolates from the denture wearers produced phospholipase and proteinase (85% and 80% respectively) compared to the strains from normal subjects (25% and 60% respectively). Only the germ tube formation and adherence ability were significantly higher in the strains from the cancer patients with prostheses (p = 0.05 and p < 0.01 respectively). In conclusion, during the commensal state, the increased expression of virulence factors in the denture wearers suggests the readiness of these strains to cause infection in this group. The high number of C. albicans and their increased adherence ability in the two study groups suggest that hygiene of oral cavity and prostheses is important in the prevention of colonization of Candida and the development of oral candidiasis.

Multilocus sequence typing (MLST) analysis of Candida albicans isolates colonizing acrylic dentures before and after denture replacement.

Yeast, in particular Candida albicans, are the principal fungal cause of denture stomatitis, and can also be present as a commensal in many individuals. Few studies, however, have examined oral retention of yeast strains over time. We analyzed the yeast present in saliva samples and from the dentures of 10 individuals colonized with yeast but with no signs of stomatitis, before new complete maxillary dentures were fitted and also at 1, 3, and 6 months after denture replacement. Yeast species were presumptively identified on selective agar plates and were present in nine individuals before denture replacement and in six at the 6-month time point. C. albicans was detected in seven individuals pre-replacement, and in three by 6 months post-replacement. Sixty-two isolates (up to five from each C. albicans-positive sample) were analyzed by multilocus sequence typing (MLST) (33 from saliva and 29 from dentures). Six MLST allele profiles were identified that were common to several individuals. These profiles included three previously reported diploid sequence types (DSTs) and three novel DSTs. Two of the novel DSTs were closely related variants of a previously reported DST, and both showed loss of heterozygosity polymorphisms within one of the seven MLST gene sequences. For three individuals, at least one DST that was present before denture replacement was still detected in either saliva or on dentures at subsequent sampling times. Our results indicate that denture replacement reduces but does not remove, colonising yeast and confirm previous observations of C. albicans strain microevolution.

The effect of enriching denture adhesives with chlorhexidine diacetate on the proliferation of Candida albicans: an in vitro analysis.

Denture adhesives are widely used in dentistry. The growth of Candida albicans on the denture base is common on both jaws, particularly in elderly patients. A strong correlation has been found between the growth of Candida albicans and dentures, potentially leading to denture stomatitis. Recent studies show that the addition of chlorhexidine diacetate (CHDA) to denture adhesives can have a protective effect against denture stomatitis. The aim of this research is to examine the antifungal properties of three denture adhesives when CHDA is added. We hypothesize that the addition of CHDA to denture adhesives will result in antifungal activity against Candida albicans. Three denture adhesive materials (Corega, Protefix and Kukident) were prepared with and without the addition of CHDA in order to measure whether CHDA increased the resistance of the adhesives to the growth of Candida albicans. Dynamic and static intercellular changes were assessed through direct contact test (DCT) and confocal microscopy. The tested materials were evaluated immediately after setting and at 14 days post-setting. When combined with CHDA, all three denture adhesive materials decreased Candida albicans growth compared to the control (p less than 0.0001). This inhibition of growth was more prominent in the first 24 h. The confocal microscopy results supported the DCT findings. The addition of CHDA to denture adhesive pastes inhibits growth of Candida albicans, and may potentially reduce the incidence of denture stomatitis. Further studies are warranted.

The oral health status of older patients in acute care on admission and Day 7 in two Australian hospitals.

Objective: to determine the oral health status of older patients in acute care wards at admission and after 7 days. Methods: a prospective descriptive study was conducted in two acute tertiary referral hospitals in New South Wales, Australia. Oral health was assessed on admission (within 24 h) and Day 7 using the Oral Health Assessment Tool. Results: a total of 575 patients were admitted under the Geriatric teams at the two hospitals. Four hundred and thirty-five (76%) patients had oral cleanliness (debris) scores in the 'not healthy' range with food particles, tartar or plaque evident in at least one area in most areas of the mouth, teeth or dentures. At Day 7 206 were reassessed. One hundred and forty-nine patients (73%) were in the 'not healthy' range and of these 127 (62%) had the same score as on admission. Conclusion: poor oral health is common in older people admitted to hospital acute care wards and does not improve over a 7-day period. Given the link between oral health and general health the next steps are to determine how oral health can be improved in this setting and see whether this leads to better patient outcomes.

Preventive oral health intervention among old home care clients.

Background: poor oral health is common among older people dependent on supportive care and it affects their quality of life. Cognitive impairment and functional dependency may increase the risk of compromised daily oral hygiene. Aim: to investigate the effectiveness of a tailored preventive oral health intervention among home care clients aged 75 years or over. Patients and methods: the intervention group comprised 151 patients (84.4 ± 5.6 years) and the control group 118 patients (84.7 ± 5.2 years). An interview and a clinical examination were carried out before a tailored intervention of oral and denture hygiene. The participants in both groups were re-interviewed and re-examined after 6 months. Results: the intervention significantly reduced the number of plaque covered teeth and improved denture hygiene. In addition, functional ability and cognitive function were significantly associated with better oral hygiene. Conclusions: the intervention had a positive effect on oral hygiene, however the number of teeth with plaque remained high, even after the intervention. Multiple approaches based on individual needs are required to improve the oral health of vulnerable older adults, including integrating dental preventive care into daily care plan carried out by home care nurses.

Antimicrobial action and long-term effect of overnight denture cleansers.

PURPOSE: To evaluate two denture cleansers for overnight soaking (0.5% sodium hypochlorite and peroxide alkaline) regarding efficacy against Candida spp. biofilms (randomized clinical trial) and their effects on the physical properties of a denture base acrylic resin simulating a period of 5 years of use (laboratory study). The Candida spp. were identified and their resistance to main antifungal agents was evaluated. METHODS: 32 complete denture wearers were instructed to brush their dentures three times a day and to soak them (≥8 hours) in: control - water (C); alkaline peroxide (AP); or 0.5% sodium hypochlorite (SH). According to a randomized sequence, each solution was used for three alternate periods of 7 days. The antimicrobial action was performed by counting the colony forming units (CFU) of Candida spp. For collection of the biofilm, each upper complete denture was placed in a Petri dish, the internal surface was brushed (Tek brush) with saline solution for 2 minutes and the suspension was transferred to a test tube. After dilutions (10 0 to 10-3), aliquots of 50 µL were seeded inside Petri dishes containing Candida Chromagar. After incubation, the colonies were counted and the values of CFU/mL calculated. Data were transformed in log10 (CFU +1) and analyzed by the Friedman test (α= 0.05) followed by Wilcoxon and Bonferroni tests (α= 0.05). Each of the different species identified perfunctorily has been confirmed through the identification of yeasts kit. The resistance to antifungal agents (amphotericin B, nystatin, flucytosine, econazole, ketoconazole, miconazole and fluconazole) was also evaluated. Adverse effects were estimated on heat-polymerized resin specimens, simulating a 5-year period of overnight use. Acrylic resin specimens were randomly distributed into three groups: C: Control (distilled water); AP: alkaline peroxide; and SH: 0.5% sodium hypochlorite. Color change, surface roughness and flexural strength were evaluated at baseline and after immersion procedures. Data were compared by Kruskall-Wallis followed by Dunn's test (color change and surface roughness) and one-way ANOVA (flexural strength) (α= 0.05). RESULTS: There was a reduction of Candida spp. counts after using both solutions (AP and SH). The Candida spp. most often isolated was C. albicans, followed by the C. glabrata. Only 24.7% of isolate strains were resistant to at least one of the tested antifungals, highlighting azole compounds. Immersion in AP [ 5.73 (5.45-5.91)] caused significantly higher color change, with lower ΔE values for C [1.12 (1.15-1.37) ] followed by SH [3.70 (3.51-3.98) ]. The NBS values were classified as "slight" for C (1.12) group and " considerable" for AP (5.27) and SH (3.40). No solution altered surface roughness significantly. Flexural strength (in MPa) was significantly lower for C (64.59), AP (63.96 ± 12.98) and SH (62.84 ± 8.62) when compared to a group without any immersion (109.12 ± 8.37). CLINICAL SIGNIFICANCE: Both solutions tested presented antimicrobial action against Candida spp. and may be useful for denture biofilm control, but should be used with caution as an overnight immersion solution since they may damage denture bases in the long-term. Candida was most frequently isolated at baseline and after using the products. Only 24.7% of isolate strains were resistant to at least one of the tested antifungals, especially with azole compounds.

Effectiveness of non-fluoride and fluoride dentifrices for denture hygiene.

OBJECTIVE: To compare the effectiveness of commonly used herbal/non-fluoride with fluoride dentifrices in order to eliminate pathogenic oral microorganisms from denture base material. MATERIALS AND METHODS: Heat-polymerized acrylic resin specimens (n = 288) were divided into three groups and each group inoculated with three various microorganisms (n = 96 for each) Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa (P. aeruginosa). Contaminated specimens were randomly assigned to the application of six herbal/non-fluoride and three fluoride dentifrices. These specimens were divided into two groups: negative and positive control (n = 3 for each). All acrylic specimens were incubated at 37 °C for 24 h for samples inoculated with bacterial strains and 37 °C for 48 h for samples inoculated with yeast strains. After the incubation period, all brain-heart infusion broths that contained disinfectant acrylic specimens were cultured on 5% sheep blood agar for bacterial counts and Sabouraud dextrose agar for yeast counts. The number of colony-forming units per millilitre (CFU/mL) were calculated. The results were analysed by Mann-Whitney U and Kruskal-Wallis tests (p = .05). RESULTS: Both herbal/non-fluoride and fluoride dentifrices were effective against Candida albicans. However, fluoride dentifrices were comparatively better than the herbal/non-fluoride dentifrices against Staphylococcus aureus and P. aeruginosa. CONCLUSIONS: Herbal dentifrices could be used, especially among the elderly who lack a degree of manual dexterity during the rinsing of dentifrice chemicals from their dentures.

Effect of sodium hypochlorite and Ricinus communis solutions on control of denture biofilm: A randomized crossover clinical trial.

STATEMENT OF PROBLEM: The prevalence of complete edentulism remains high in the elderly, and previous data have shown that poor denture hygiene is common among patients with edentulism. PURPOSE: The purpose of this randomized crossover trial was to evaluate the efficacy of denture cleansers in terms of biofilm removal, antimicrobial action, and the remission of denture stomatitis. MATERIAL AND METHODS: Fifty denture wearers with denture stomatitis were instructed to brush their dentures (brush and soap) and to soak them (20 minutes/14 days) in 4 solutions, as follows: C (control), 0.85% saline; SH1, 0.1% sodium hypochlorite; SH2, 0.2% sodium hypochlorite; and RC, 8% Ricinus communis. The biofilm in the intaglio surface of maxillary dentures was stained, photographed, and quantified by software (Image Tool). It was then collected (brushed with saline solution), and the obtained suspension was diluted (100 to 10-3) and seeded (50 µL) in CHROMagar for Candida spp. After incubation, colony-forming units per milliliter values were calculated. Denture stomatitis remission was classified according to the Newton classification. Data were analyzed by Friedman (α=.05) and Wilcoxon tests and corrected by the Bonferroni test (α=.005). RESULTS: SH1 (mean rank [MR]=1.98) and SH2 (MR=1.64) showed lower biofilm coverage than C (MR=3.73) that was similar to RC (MR=2.92). SH1 (MR=2.43) and SH2 (MR=2.10) showed antimicrobial action for Candida spp, and RC (MR=3.36) showed similar results to C (MR=3.51) and baseline (MR=3.50). Clinical signs of denture stomatitis were reduced by SH1 (MR=2.44), while SH2 (MR=2.56) and RC (MR=2.74) showed intermediate results. CONCLUSIONS: The two sodium hypochlorite solutions were the most effective means of biofilm control. All tested solutions were effective in reducing the signs of denture stomatitis.

Chemical Methods for Cleaning Conventional Dentures: What is the Best Antimicrobial Option? An In Vitro Study.

PURPOSE: To investigate the antimicrobial efficacy of different chemical agents used for denture cleaning. MATERIALS AND METHODS: Biofilm samples collected from 10 removable dentures were subjected to 10 disinfection protocols: distilled water for 30 min (negative control); 1% sodium hypochlorite for 10 min (positive control); diluted sodium hypochlorite for 10 min; vinegar for 20 min; 0.2% peracetic acid for 5 min; alkaline peroxide solution for 5 min; alkaline peroxide solution for 30 min; 0.12% chlorhexidine digluconate for 10 min; 0.05% sodium salicylate solution for 10 min; and enzymatic detergent for 2 min. Each of the samples was plated on petri dishes with Mueller-Hinton agar. The numbers of microbial colonies after 48 h at 37°C were compared using the Kruskal-Wallis and Dunn's tests (α = 0.05). RESULTS: Diluted sodium hypochlorite, vinegar, and chlorhexidine digluconate inhibited bacterial growth, with an effect similar to that of 1% sodium hypochlorite. The 0.2% peracetic acid and 0.05% sodium salicylate solutions were ineffective against bacterial growth, while enzymatic detergent and alkaline peroxide achieved an intermediate effect. CONCLUSION: Diluted sodium hypochlorite, vinegar, and chlorhexidine digluconate can be considered adequate products for cleaning dentures due to their potential for inhibiting bacterial growth, similar to 1% sodium hypochlorite. However, the effect of these chemical agents on acrylic resin (polymethylmethacrylate) denture base materials needs to be examined to provide complete information about their clinical indication.

Adjuvant antifungal therapy using tissue tolerable plasma on oral mucosa and removable dentures in oral candidiasis patients: a randomised double-blinded split-mouth pilot study.

Extended use of antimycotics in oral candidiasis therapy gives rise to problems related to fungal drug resistance. The aim of this pilot study was to investigate the efficacy of tissue tolerable plasma (TTP) in denture stomatitis patients. It was hypothesised that (I): erythema and (IIa): complaint remission would be accelerated and (IIb): colony forming unit (CFU) reduction would be improved. The halves of the upper jaws of eight patients were randomly assigned to control (nystatin, chlorhexidine and placebo treatment) and test sides (nystatin, chlorhexidine and TTP administered six times each 7 days). The patients and the investigators, who were different from the therapists, were both blinded. Compared to the control sides, the erythema surface was reduced significantly more extensively on the test sides between 2 and 6 weeks of antifungal therapy (P ≤ 0.05). Visual analogue scale values and the frequency of moderate or heavy growth of Candida post-treatment did not differ significantly between both sides (P > 0.05). The primary hypothesis was confirmed, which may be interpreted as an accelerated remission. As drug therapy is usually limited to the time in which signs of infection are present, TTP might help reducing antifungal use. Even though the secondary hypotheses were not confirmed, persistence of Candida might be only colonisation.

Antimicrobial efficacy of complete denture cleansers.

PURPOSE: To evaluate the in vitro antimicrobial efficacy of alkaline peroxides against microbial biofilms on acrylic resin surfaces. METHODS: Denture base acrylic resin (Lucitone 550; n= 360) circular specimens (15 x 3 mm) were obtained from a circular metal matrix and sterilized with microwave irradiation (650 W, 6 minutes). The specimens were then contaminated with suspensions [106 colony-forming units (CFU)/mL] of Candida albicans (Ca), Candida glabrata (Cg), Staphylococcus aureus (Sa), Streptococcus mutans (Sm), Bacillus subtilis (Bs), Enterococcus faecalis (Ef), Escherichia coli (Ec), and Pseudomonas aeruginosa (Pa). After contamination, the specimens were incubated at 37 degrees C for 48 hours and then placed in a stainless steel basket, which was immersed in a beaker with one of the following solutions prepared and used according to the manufacturers' instructions (n= 10 per group): Group PC (positive control), phosphate-buffered saline (PBS) solution; Group MI, NitrAdine, Medical Interporous; Group EF, Efferdent Plus; Group CT, Corega Tabs; and Group NC (negative control; n= 5), no contamination and immersed in PBS. After incubation (37 degrees C, 24 hours), the number of colonies with characteristic morphology was counted, and CFU/mL values were calculated. The data were processed following the transformation into the formula log" (CFU + 1) and statistically analyzed by the Kruskal-Wallis and Dunn's tests (alpha = 0.05). RESULTS: There were significant differences between the groups for the evaluated microorganisms with a significant reduction in the CFU/mL. MI was effective for Ca, Cg, Sa, Sm, Ef, Ec and Pa; EF was effective for Cg, Sm, Ef, Ec and Pa; and CT was effective for Sa, Bs and Ec, when compared with the PC group.

Potential respiratory pathogens colonisation of the denture plaque of patients with chronic obstructive pulmonary disease.

INTRODUCTION: The role of bacterial infections in acute exacerbations of chronic obstructive pulmonary disease (COPD) is widely examined. Denture plaque in patients with COPD is an example of bacterial and fungal biofilm, which is a reservoir of potentially pathogenic respiratory tract microorganisms. Poor denture hygiene might cause acute exacerbations of COPD. OBJECTIVE: Assessment of prevalence of respiratory tract pathogens in denture plaque in stable patients with COPD and it influence on oral ontocenoses depending upon the therapy. MATERIALS AND METHODS: The study was based on the clinical assessment of oral mucosa and denture hygiene in 53 patients with COPD with mean age of 70 ± 18 years and 14 generally healthy participants with mean age of 65 ± 14 years. Microbiological and mycological tests were performed by culturing direct denture swabs. RESULTS: The study showcased the presence of potential pathogenic micro-organisms in denture plaque of 48 patients with COPD (90%) and nine healthy subjects (64.3%). Yeast-like fungi prevailed in denture surface swabs of 40 (75%) in patients with COPD and 8 (57%) in cases of control group. In 66% of patients, various degree of oral mucosa inflammation prevailed. CONCLUSIONS: Denture plaque could be a potential source of bacterial and fungal infections in patients with COPD.

Evaluating the efficiency of humic acid to remove micro-organisms from denture base material.

OBJECTIVE: To evaluate the efficiency of humic acid substances on removing micro-organisms from denture base materials. BACKGROUND: Old denture wearer needs effective, easy-use and safe denture-cleaning material. MATERIAL AND METHODS: Square-shaped, heat-polymerised acrylic resin specimens (n = 550) were prepared and divided into five groups (n = 110 for each) corresponding to the microbial contamination (Candida albicans, Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Pseudomonas aeruginosa). Contaminated specimens were randomly assigned to the application of five different denture-cleaning agents as follows (n = 20 for each): Kloroben, Corsodyl, Steradent, Corega, experimental solution with humic acid. Ten specimens were assessed as an experimental control carried out simultaneously for the treatment groups for each micro-organism. It was divided into two groups: negative control and positive control (n = 5 for each). All acrylic specimens were incubated 37°C for 24 h (for bacterial strains) and 37°C for 48 h (for yeast strains). After incubation period, all brain-heart infusion broths (BHI) which contain disinfectant acrylic specimens were cultured on 5% sheep blood agar (for bacteria) and Sabouraud dextrose agar (SDA) for yeast using loop. The numbers of colony-forming units per millilitre (CFU/ml) were calculated. The results were analysed by Mann-Whitney U-test and Kruskal-Wallis tests (p = 0.05). RESULTS: Corsodyl and Kloroben completely eliminated the adherence of all investigated micro-organisms (100%) and showed the highest removal activity compared with other cleaning agents (p < 0.05). There was no statistically significant difference between Corsodyl and Kloroben (p ≥ 0.05), and there was no statistically significant difference between Corega, Steradent and experimental solution (p ≥ 0.05). CONCLUSION: Humic acid could be used as an alternative 'natural' solution for denture-cleaning agent.

Influence of melaleuca and copaiba oils on Candida albicans adhesion.

OBJECTIVE: To evaluate the efficacy of Melaleuca alternifolia and Copaifera officinalis in inhibiting the adhesion of Candida albicans biofilm. BACKGROUND: Over 65% of denture wearers suffer from denture stomatitis, which is one of the most prevalent forms of oral candidiasis. This disease is characterised by the inflammation of the oral mucosa in contact with the contaminated denture. The contaminated denture contributes to the switch of C. albicans from yeast to its pathogenic hyphal form. Candida albicans adheres and colonises the polymethylmethacrylate resin surfaces and thus contributes to the development of denture stomatitis. MATERIALS AND METHODS: The minimal inhibitory concentration (MIC) of M. alternifolia and Co. officinalis was assessed by the agar dilution method. Sixty-six thermopolymerised acrylic resin squares were used and treated with phosphate-buffered saline, sodium hypochlorite 1%, melaleuca 0.75%, melaleuca 0.375%, melaleuca 0.188% and copaiba 10%. For adherence and biofilm formation, the treated squares were placed in six-well tissue culture plates containing 1 × 10(7)  cells/ml of ATCC1023 or SC5314 in Roswell Park Memorial Institute (RPMI) medium, and after 12 h, the planktonic cells were counted. RESULTS: Copaiba oil did not inhibit C. albicans growth. However, melaleuca oil showed an MIC value of 0.375% (3.4 mg/ml) for ATCC10231 and 0.093% (0.84 mg/ml) for SC5314. CONCLUSIONS: Our results demonstrated that M. alternifolia oil inhibited the growth of C. albicans. Moreover, both oils promoted significant adhesion reduction in the tested strains. These findings suggest the possibility of using these oils in prophylaxes against candidiasis.

Host contributions to construction of three device-associated Candida albicans biofilms.

Among the most fascinating virulence attributes of Candida is the ability to transition to a biofilm lifestyle. As a biofilm, Candida cells adhere to a surface, such as a vascular catheter, and become encased in an extracellular matrix. During this mode of growth, Candida resists the normal immune response, often causing devastating disease. Based on scanning electron microscopy images, we hypothesized that host cells and proteins become incorporated into clinical biofilms. As a means to gain an understanding of these host-biofilm interactions, we explored biofilm-associated host components by using microscopy and liquid chromatography-mass spectrometry. Here we characterize the host proteins associated with several in vivo rat Candida albicans biofilms, including those from vascular catheter, denture, and urinary catheter models as well as uninfected devices. A conserved group of 14 host proteins were found to be more abundant during infection at each of the niches. The host proteins were leukocyte and erythrocyte associated and included proteins involved in inflammation, such as C-reactive protein, myeloperoxidase, and alarmin S100-A9. A group of 59 proteins were associated with both infected and uninfected devices, and these included matricellular and inflammatory proteins. In addition, site-specific proteins were identified, such as amylase in association with the denture device. Cellular analysis revealed neutrophils as the predominant leukocytes associating with biofilms. These experiments demonstrate that host cells and proteins are key components of in vivo Candida biofilms, likely with one subset associating with the device and another being recruited by the proliferating biofilm.

Colonisation of dentures by Staphylococcus aureus and MRSA in out-patient and in-patient populations.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen, and colonisation with this organism can result in localised or systemic infections which may be fatal. One hundred in-patients admitted to a London teaching hospital and 100 out-patients attending prosthetic dentistry clinics were recruited into this study. Of the 100 out-patients, 27 % harboured S. aureus on their dentures, compared to 33 % of in-patients. Only one out-patient had MRSA colonising their dentures whereas 12 % of the in-patients harboured MRSA. The median total bacterial count of the denture plaque samples was 6.2 × 10(7) cfu/sample and 6.9 × 10(7) cfu/sample for the out-patient and in-patient populations, respectively. In most instances, where present, S. aureus comprised less than 1 % of the total viable denture microbiota. Phage typing demonstrated that EMRSA-15 and non-typeable strains were harboured on dentures. The results of this study have revealed that dentures are a potential reservoir of MRSA and so account should be taken of these findings when planning decontamination procedures for elimination of this pathogen.

The Prevalence of Oral Inflammation Among Denture Wearing Patients with Chronic Obstructive Pulmonary Disease.

Oral inflammation is an important contributor to the etiology of chronic obstructive pulmonary disease, which can impact patient's health status. Previous studies indicate that people with poor oral health are at higher risk for nosocomial pneumonia. Denture wearing is one promoting factor in the development of mucosal infections. Colonization of the denture plaque by Gram-negative bacteria, Candida spp., or other respiratory pathogens, occurring locally, may be aspirated to the lungs. The studies showed that chronic obstructive pulmonary disease (COPD) patients treated with combinations of medicines with corticosteroids more frequently suffer from Candida-associated denture stomatitis. Treatment of oral candidiasis in patients with COPD constitutes a therapeutic problem. Therefore, it is essential to pay attention to the condition of oral mucosal membrane and denture hygiene habits. The guidelines for care and maintenance of dentures for COPD patients are presented in this paper. The majority of patients required improvement of their prosthetic and oral hygiene. Standard oral hygiene procedures in relation to dentures, conducted for prophylaxis of stomatitis complicated by mucosal infection among immunocompromised patients, are essential to maintain healthy oral tissues. The elimination of traumatic denture action in dental office, compliance with oral and denture hygiene, proper use and storage of prosthetic appliances in a dry environment outside the oral cavity can reduce susceptibility to infection. Proper attention to hygiene, including brushing and rinsing the mouth, may also help prevent denture stomatitis in these patients.