Model system for the in vitro testing of a synthetic histidine peptide against Candida species grown directly on the denture surface of patients with denture stomatitis

Efficacy of three denture brushes on biofilm removal from complete dentures

The aim of this study was to compare the efficacy of three denture brushes (Bitufo-B; Medic Denture-MD; Colgate-C) on biofilm removal from upper and lower dentures using a specific dentifrice (Corega Brite). The correlation between biofilm levels on the internal and external surfaces of the upper and lower dentures was also evaluated. A microbiological assay was performed to assess the growth of colony-formed units (cfu) of Candida yeasts on denture surface. Thirty-three patients were enrolled in a 10-week trial divided in two stages: 1 (control) - three daily water rinses within 1 week; 2 - three daily brushings within 3 weeks per tested brush. Internal (tissue) and external (right buccal flange) surfaces of the complete dentures were disclosed (neutral red 1%) and photographed. Total denture areas and disclosed biofilm areas were measured using Image Tool 3.00 software for biofilm quantification. Dentures were boxed with #7 wax and culture medium (CHROMagar Candida) was poured to reproduce the internal surface. Statistical analysis by Friedman's test showed significant difference (p<0.01) between control and brushing stages. No difference was found among the brushes with respect to their efficacy on biofilm removal (p>0.01). Analysis by the Correlation test showed higher r values (B=0.78; MD=0.8341, C=0.7362) for the lower dentures comparing the surfaces (internal and external) and higher r values (B=0.7861, MD=0.7955, C=0.8298) for the external surface comparing the dentures (upper and lower). The results of the microbiological showed no significant difference (p>0.01) between the brushes with respect to the frequency of the species of yeasts (chi-square test). In conclusion, all denture brushes evaluated in this study were effective in the removal of biofilm. There was better correlation of biofilm levels between the surfaces for the lower dentures, and between the dentures for the external surface. There was no significant difference among the brushes regarding the frequency of yeasts.

Candida-associated denture stomatitis. Aetiology and management: a review. Part 2. Oral diseases caused by Candida species

Certain systemic conditions and/or defects in the immune system may predispose the host to oral candidal infection and the commonest form of oral candidosis is candida-associated denture stomatitis. Until recently there has been controversy concerning the aetiology of the disease. Although some earlier investigators linked denture stomatitis with trauma or bacterial infection, others had isolated Candida albicans from the mouths of patients with the condition. Current studies indicate that denture stomatitis lesions are associated with the detection of candida species while other factors such as denture hygiene, trauma, systemic diseases and deficiencies of the immune system may be involved.

Assessment of antimicrobial treatment of denture stomatitis using an in vivo replica model system: therapeutic efficacy of an oral rinse

Five denture stomatitis patients demonstrating Candida albicans on both maxillary dentures and palates volunteered to test the effects of Peridex oral rinse in treating their oral disease. They used Peridex rinse both as a mouthrinse and as a denture soak for a period of 24 days. Agar replicas of the tissue-fitting surfaces of the maxillary dentures revealed elimination of C. albicans. Significant decreases in palatal inflammation were also noted, although some inflammation was still evident. Several weeks after the termination of Peridex oral rinses, inflammation increased as concentrations of C. albicans on the denture surface returned to pretreatment levels. A marked similarity in the site-specific localization of this yeast species on the denture was noted before and after Peridex rinse treatment.

In vivo antifungal efficacy of salivary histidine-rich polypeptides: preliminary findings in a denture stomatitis model system

Six denture stomatitis patients, all found to have Candida albicans on their maxillary denture and palatal tissue surfaces, volunteered in this preliminary study to test the in vivo efficacy of human salivary antifungal histidine-rich polypeptides (HRPs) in treating their oral disease. The patients were equally divided among the Newton types classification and, as expected, the severity of the inflammation was greatest in the Newton type III patients and least in the Newton type I patients. Patients received sterile solutions of either HRP-3 or HRP-4, which they used both as a mouthrinse and as a denture soak for a period of 1 week. Agar replicas of the tissue-fitting surface of the maxillary dentures revealed HRP reduction and/or elimination of C. albicans from the denture; in one Newton type II individual, this finding directly correlated with a site-specific reduction in palatal inflammation. In the Newton type II and type III individuals alike, there was a significant generalized decrease in inflammation suggesting the therapeutic efficacy of the HRPs. Killing of this yeast species by the HRPs, as determined by scanning electron microscopy (SEM), was probably responsible for the observed clinical benefits noted in this investigation. In the SEM, HRP-treated blastospores appeared severely deflated, as if they had been emptied of significant quantities of intracellular material.

In vivo and in vitro studies on soft denture materials: microbial adhesion and tests for antibacterial activity

The microbiological properties of four tissue conditioners, one soft liner, and one acrylic resin were studied. The tissue conditioners showed no or negligible antimicrobial effects toward salivary microorganisms by two different in vitro tests. In in vitro adhesion experiments, more Streptococcus mutans and Candida albicans adhered to the tissue conditioners and the soft liner in comparison with conventional acrylic resin used for denture-base fabrication. No difference in bacterial adhesion was found among the tissue conditioners. The microbial colonization of two tissue conditioners lined on maxillary dentures in three volunteers was followed for 14 days. No difference among the materials was found, but a tendency for subject-dependence in plaque formation on the materials was noted.

Role of pH in salivary histidine-rich polypeptide antifungal germ tube inhibitory activity

Purified synthetic salivary histidine-rich polypeptides (HRPs) 2, 3, 4, 5 and 6 were found to inhibit Candida albicans conversion of blastospores to germ tubes. HRP-4 was the best inhibitor within the pH 5 to 7 range tested and all of the HRPs were observed to lose potency as the pH was raised from 5 to 7. The pH pattern obtained with a synthetic homologous histidine peptide suggested that the protonated form of the histidine imidazole residues of the HRPs was important to the germ tube antifungal activity. Similar pH inhibition profiles of germ tube formation by parotid saliva and the HRPs were also observed.

An in vivo replica method for the site-specific detection of Candida albicans on the denture surface in denture stomatitis patients: correlation with clinical disease

A site-specific agar replica technique for detecting Candida albicans on the acrylic resin denture surface of denture stomatitis patients has been developed. The method is selective for C. albicans during a finite incubation period with a specific synthetic growth medium. C. albicans colonies can be geographically observed on the replica and their presence can be correlated with inflammatory lesions visible on the mucosa of the maxillary and mandibular residual ridges. In 12 denture stomatitis patients studied, a close clinical correlation of Newton type III patients was noted but this clinical correlation could not be observed in Newton type I and II patients. In general, the number of C. albicans colonies increased with the severity of the inflammation. The findings are discussed in light of lack of knowledge of the etiology of the stomatitis. The importance of the replica method is also discussed.