The aim of this study was to identify and characterize aetiological and predisposing factors in denture-related stomatitis (DRS), by means of a case-control, transversal study, in a large cohort of 140 persons wearing removable maxillary polymethylamethacrylate prostheses. Data were obtained by (1) a questionnaire that included the identification of the subject, demographic and social data, medical history and behaviour; (2) intra-oral examination; (3) evaluation of the prosthesis; (4) microbiological examination; (5) yeast identification and analyses using Epi-info and the chi-square test. Results showed significant associations between DRS and yeasts, gender, age and alcohol consumption. We also found a significant relationship between the presence of yeasts and hyposalivation and decreased salivary pH. We found a highly significant difference between groups with and without DRS concerning the presence or absence of yeasts, regardless of the sample origin. Most cases of DRS showed the presence of Candida albicans. The results confirm a highly significant difference between groups with and without DRS concerning the presence or absence of yeasts.

The results reinforced the idea that C. albicans is the most frequent and can be the most pathogenic yeast in oral candidosis. However, the strains isolated from DRS patients and healthy individuals showed the same virulence factors. It seems that several virulence attributes are involved in the infective process but no single factor contributes to Candida virulence. Candida dubliniensis was absent in the oral cavity of individuals with and without DRS.

Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles.

Objective: Denture-wearing favours the growth of Candida. In view of the fact that many denture wearers regularly use adhesives to enhance denture retention, stability and function, the aim of this work was to study the effect of denture adhesives on Candida albicans growth in vitro. Materials and methods: The denture adhesives tested were CoregaÒ powder and Corega Ò strip. C. albicans growth curves were obtained in the presence or absence of a 1% solution of the denture adhesive diluted in Sabouraud broth. Macro-and microscopic morphological changes in C. albicans were analysed, as was microbial contamination of the denture adhesive. Results: Most of the denture adhesives studied induced morphological changes in C. albicans cells and colonies, but only two had any significant inhibitory effect on yeast growth. Kukident Ò cream markedly inhibited C. albicans growth in a concentration-dependent way, reducing the growth rate by 95%, whereas Corega Ò cream also inhibited C. albicans growth but in a non-concentration-dependent way, reducing the growth rate by 37%. In addition, denture adhesives available as powders had detectable microbial contamination. Conclusion: Some commercially available denture adhesives showed microbial contamination and some had significant inhibitory effect on C. albicans growth.

Denture-related stomatitis (DRS) is the most common condition affecting removable-denture wearers, and Candida albicans the most frequent pathogenic agent. Systemic antifungal treatment is indicated but recurrences are frequent. The aim of this study was to characterize the oral load, fluconazole susceptibility profile and genotypic variability of oral C. albicans isolates from patients with DRS before (T0), immediately after fluconazole treatment (Tat) and after 6-months follow-up (T6m). Eighteen patients presenting DRS and treated with fluconazole were followed at the Faculty of Dentistry of Oporto University. Seventy C. albicans isolates were obtained and identified using standard cultural and biochemical multi-testing. Fluconazole susceptibility was tested by E-test®. Microsatellite-primed PCR was performed to assess the genotypic variability of C. albicans isolates. The patients’ mean age was 58.0±3.2 years, and 55.6%/44.4% had total/partial dentures. Before treatment, 22.2%, 44.4% and 33.3% of the patients presented DRS type I, II or III, respectively. Fluconazole treatment healed or improved DRS in 77.8% of the patients, accompanied by an 83.5% reduction in oral C. albicans load. However, after 6-months, oral C. albicans load increased significantly and DRS severity was similar to the one observed before treatment. Moreover, the prevalence of patients presenting fluconazole resistant isolates of C. albicans increased significantly throughout the study: T0-5.6%, Tat-10.0% and T6m-42.9%. A change in the genotypic variability of C. albicans isolates was also verified, being mostly associated to fluconazole susceptibility profile change. In conclusion, fluconazole presents a good short-term DRS treatment efficiency, but may be associated to a long-term emergence of C. albicans fluconazole resistance.