Influence of the use of complete denture adhesives on microbial adhesion and biofilm formation by single- and mixed-species.

OBJECTIVES: To verify whether the Ultra Corega Cream and Corega Strip Denture Adhesive adhesives interfere in the microbial adhesion and biofilm formation by Candida albicans and Lactobacillus casei in single- and mixed-species settings, and observe whether synergistic or antagonistic relationships between these species occur. METHODS: Specimens made from heat-polymerized acrylic resin (Lucitone 550) were fabricated (n = 144) with a circular shape and standardized roughness (3.0 µm ±0.3 Ra) and were divided into three groups: Without Adhesive (WA), with Ultra Corega Cream adhesive (CA) and Corega Strips adhesive (SA). These groups were divided into three subgroups each: C. albicans single-species, L. casei single-species and C. albicans with L. casei (mixed-species). Microbial adhesion and biofilm formation assays were performed in duplicate at four distinct experimental times (n = 8 per experimental condition). The amount of each microorganism on the surfaces of the specimens was observed by counting of the Colony Forming Units (CFU) per substrate. Additional specimens were characterized by Scanning Electron Microscopy (SEM), with 18 specimens being used in this analysis (n = 18), 2 per experimental condition (n = 2). Two-way ANOVA and Tukey's test for multiple comparisons were employed, using α≤0.05. RESULTS: L. casei (mixed-species) adhered more on the WA substrate than the CA, while C. albicans (single- and mixed-species) adhered more on the SA. C. albicans, both single- and mixed-species adhered more than the L. casei (single- and mixed-species), regardless of the substrate. L. casei (single-species) formed more biofilm on the WA, but in its mixed cultivation, it had no difference of growth among the tested situations. C. albicans (single- and mixed-species) formed more biofilm on the SA than the CA, and the fungus formed more biofilm when compared to L. casei. In general, whenever a species was compared in its single- and mixed-species situation, no statistically significant difference was observed. SEM of biofilm formation assays demonstrated that L. casei single-species WA formed more biofilm than when the adhesives tested were used, and C. albicans (both single- and mixed-species) formed more biofilm on the SA than on the CA. CONCLUSIONS: (1) The two denture adhesives tested increased the adhesion of C. albicans but not of L. casei; (2) biofilm formation by C. albicans (single- and mixed-species) was increased on the SA; (3) Relations of synergism or antagonism was not observed between the two microorganisms studied.

Proinflammatory cytokine production from NOK-SI keratinocytes after exposure to denture adhesives.

STATEMENT OF PROBLEM: Although the cytotoxicity of denture adhesives has been widely assessed, data on the release of proinflammatory cytokines from oral epithelial cells are still scarce. PURPOSE: The purpose of this in vitro study was to evaluate the proinflammatory cytokines interleukin (IL) 1ß, IL-6, and tumor necrosis factor α (TNF-α) released from human oral keratinocytes after exposure to denture adhesives. MATERIAL AND METHODS: Eluates of the Ultra Corega cream, Corega powder Fixador Ultra, and Corega strip denture adhesives were created at 1% wt/vol after 24 hours of exposure in a Dulbecco modified Eagle medium culture. The release of IL-1ß, IL-6, and TNF-α was measured using a sandwich enzyme-linked immunosorbent assay after the oral epithelial cells (NOK-SI) had been exposed to the eluates for 3, 6, and 24 hours (n=6). RESULTS: IL-1ß release from the strip was higher at 3 hours compared with the control (Bonferroni post hoc test, P=.016). IL-6 releases from the cream and powder denture adhesives at 6 and 24 hours were higher than for the controls (Bonferroni post hoc test, P<.05). TNF-α release was not detectable in some groups and periods. CONCLUSIONS: In long periods, denture adhesive strips do not induce any change on cytokine release from human oral keratinocytes.

Crossover clinical trial of different methods of removing a denture adhesive and the influence on the oral microbiota.

STATEMENT OF PROBLEM: The difficulty of removing denture adhesive is a common problem reported by users of these products. PURPOSE: The purpose of this clinical study was to investigate the effectiveness of different cleaning protocols for removing a denture adhesive (DA) and the influence on the oral microbiota. MATERIAL AND METHODS: Twenty participants wearing well-fitting complete dentures were instructed to use a denture adhesive 3 times a day during a 4-week trial, divided into 4 stages: (A) control-3 daily denture brushings using water at ambient temperature, (B)-3 daily denture brushings using water at ambient temperature plus coconut soap, (C)-3 daily denture brushings using water at ambient temperature plus dentifrice; (D)-3 daily denture brushings using water at ambient temperature combined with immersion in sodium perborate solution for 5 minutes before nocturnal sleep. After each 1-week stage, saliva specimens were collected. A dye was used to display and quantify the remaining DA on the internal surface of the maxillary dentures as a percentage. For microbiological analysis, the saliva was diluted and plated onto Petri dishes containing a nonselective culture medium and Candida spp culture media. After the incubation period, Candida species were identified and the number of colony forming units (CFU/mL) was calculated. RESULTS: A significant difference was found among the 4 cleaning methods for the quantification of remaining DA (Friedman, P=.036). Brushing the dentures with coconut soap, dentifrice, or water combined with immersion in sodium perborate solution was more effective in removing DA than brushing with only water. The cleaning methods did not influence the quantification of microorganisms in general or Candida albicans and other Candida species in particular. CONCLUSIONS: Brushing the dentures with coconut soap, dentifrice, or water combined with immersion in sodium perborate solution was more effective for removing cream-type denture adhesive than brushing with only water.

Reestablishment of Occlusal Vertical Dimension in Complete Denture Wearing in Two Stages.

The assessment and reestablishment of the occlusal vertical dimension (OVD) are considered important factors in the treatment of complete denture wearers. The long-time use of a complete denture can result in jaw displacement due to abrasion of the artificial teeth and residual ridge resorption, causing esthetic complications. Most patients with old dentures and incorrect OVD accept reestablishment of the OVD with new complete dentures, even if they were used to their old dentures. The present clinical report describes a method of gradual reestablishment of OVD using a diagnostic acrylic splint on artificial teeth in old complete dentures before the manufacture of new complete dentures. Clinical Significance. The use of a reversible treatment for reestablishment of the OVD in old complete dentures with a diagnostic occlusal acrylic splint allows for the reestablishment of the intermaxillary relationship, providing physiological conditions of masticatory performance associated with the recovery of facial esthetics in edentulous patients.

Masticatory performance of complete denture wearers after using two adhesives: a crossover randomized clinical trial.

STATEMENT OF PROBLEM: Masticatory performance analysis of conventional complete denture wearers who use denture adhesives is scarce in the dental literature. PURPOSE: The purpose of this study was to assess the effect of the use of 2 denture adhesives on the masticatory performance of conventional complete denture wearers by means of a crossover study. MATERIAL AND METHODS: Forty individuals who were edentulous received new maxillary and mandibular complete dentures, and, after an adaptation period, were submitted to masticatory performance analysis without denture adhesive (control). The participants were randomly divided and assigned to 2 protocols: protocol 1, denture adhesive 1 (Ultra Corega cream tasteless) use during the first 15 days, followed by no use of denture adhesive over the next 15 days (washout), and then use of denture adhesive 2 (Ultra Corega powder tasteless) for 15 days; protocol 2, denture adhesive 2 (Ultra Corega powder tasteless) use during the first 15 days, followed by no use of denture adhesive during the next 15 days (washout), and then use of denture adhesive 1 (Ultra Corega cream tasteless) for 15 days. The masticatory performance was assessed immediately after the use of denture adhesive by means of the sieve method, in which participants were instructed to deliberately chew 5 almonds for 20 chewing strokes. Masticatory performance was calculated by the weight of comminuted material that passed through the sieves. Data were analyzed by a 1-way ANOVA for paired samples and the multiple comparison of means by using the Bonferroni test (α=.05). RESULTS: A significant increase in masticatory performance was noted after using the Ultra Corega cream (mean, 32.6%) and Ultra Corega powder (mean, 31.2%) when compared with the control group (mean, 19.8%) (P<.001). No significant difference was found between the 2 denture adhesives evaluated. CONCLUSION: The use of denture adhesive improved the masticatory performance of conventional complete denture wearers. No difference was found in masticatory performance with the use of cream or powder denture adhesive.

Chemical characterization and flexural strength of a denture base acrylic resin with monomer 2-tert-butylaminoethyl methacrylate.

PURPOSE: The objectives of this study were to investigate the flexural strength (FS) and chemical interaction between 2-tert-butylaminoethyl methacrylate (TBAEMA) and a denture base acrylic resin. MATERIALS AND METHODS: Specimens were divided into five groups according to the concentration of TBAEMA incorporated in acrylic resin Onda-Cryl (0%, 1%, 2%, 3%, 4%) and were submitted to Fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (XPS-ESCA), and differential scanning calorimetry (DSC) analyses. FS of the specimens was tested, and results were analyzed by ANOVA/Tukey's test (α < 0.05). RESULTS: Different nitrogen ratios were observed on specimens' surfaces: 0.36%, 0.54%, 0.35%, and 0.20% for groups 1%, 2%, 3%, and 4%, respectively. FTIR indicated copolymerization of acrylic resin and TBAEMA, and DSC results demonstrated a decrease in glass transition temperature (Tg ). Significant differences were found for FS (p < 0.05). The mean values were 91.1 ± 5.5,(A) 77.0 ± 13.1,(B) 67.2 ± 12.5,(B) 64.4 ± 13.0,(B) and 67.2 ± 5.9(B) MPa for groups 0%, 1%, 2%, 3% and 4%, respectively (same superscript letters indicate no significant difference). CONCLUSIONS: The incorporation of TBAEMA in acrylic resin resulted in copolymerization and the presence of amine groups on specimens' surfaces, and in decreases of Tg and FS.