Candida albicans adhesion on 3D-printed and thermopolymerizable polymethyl methacrylate for removable prostheses.

PURPOSE: To compare Candida albicans adhesion and quantify the biofilm formed on thermopolymerizable (T.PMMA) and 3D printing (3D.PMMA) polymethyl methacrylate through quantitative and qualitative analyses. METHODS: The specimens were made (n= 39/material) by conventional polymerization (T.PMMA) and designed in Autodesk Meshmixer software, followed by 3D printing (3D.PMMA) - CAD-CAM method. After the roughness standardization, the monospecies biofilm of C. albicans (ATCC 10231) was submitted to adhesion analysis, verifying the quantification and microbial load, in triplicate, by the methods of counting colony forming units (CFU/mL) and staining with crystal violet, followed by optical density reading, respectively. Qualitative analyses were performed by scanning electron microscopy to analyze the surface characteristics of the specimens and biofilm formed. The Mann-Whitney U test was used for comparisons between resins regarding the count of CFU/mL (log¹°+ 1) and optical density values (P≤ 0.05). RESULTS: T.PMMA (5.78 ± 0.43) had a CFU/mL count (P< 0.001) higher than 3D.PMMA (4.84 ± 0.39). There was a difference between C. albicans biofilm accumulation (P< 0.001), in which on T.PMMA (1.59 ± 0.31) was higher than 3D.PMMA (1.10 ± 0.14). The qualitative analyses corresponded to the quantitative ones and allowed the visualization of more porosities in T.PMMA. CLINICAL SIGNIFICANCE: The adhesion (microbial load and biofilm accumulation) of C. albicans was lower in the 3D printed polymethyl methacrylate when compared to the thermopolymerizable model.

Denture cleanser effect on resilient liners with distinct optical characteristics.

PURPOSE: To evaluate denture cleansing solutions regarding the surface roughness and color stability of two resilient liners with distinct optical characteristics used for the maximum recommended period of use. METHODS: The specimens of each resilient liner, transparent and white, were randomly distributed into groups (n= 15) of a daily 20-minute immersion simulation of 0.25%, 0.5% and 1% sodium hypochlorite (SH) and 4% acetic acid solutions. Surface roughness (Ra) and color stability (ΔE CIELab formula and NBS systems) were measured after 7, 14, 21, 30, 60, 90, 180, and 270 days. The factors of variations analyzed were material, solutions, and time of immersion. Statistical analysis used three-way ANOVA and Tukey tests (Ra), and repeated measure ANOVA (ΔE and NBS systems), P< 0.05. RESULTS: For Ra analysis, the variations occurred regardless of time and solution, as the white liner showed the greatest changes (P< 0.001). Regarding interactions between solution and time, in the period of 21 days until 270 days, Ra was equivalent for all solutions (P= 0.001). ΔE analysis showed a difference between solutions (P= 0.000) and interaction between time and solution (P= 0.000). For the transparent liner, the greatest changes were found for 1% SH after 60 days, however, at 270 days there was a color change equivalence with 0.5% SH, while 4% acetic acid solution showed intermediate values. For the white liner, 1% SH showed the highest color changes for all evaluated times, and the other evaluated solutions were similar after 270 days. For both resilient liners, 0.25% SH showed the smallest changes for the evaluated properties. CLINICAL SIGNIFICANCE: The changes found were dependent on the concentration of the solution used, as well as the length of exposure to the solution. In addition, the white resilient liner showed to be less susceptible to color changes. For both resilient liners, 0.25% sodium hypochlorite showed the least changes for the evaluated properties.

Evaluation of biofilm removal and adverse effects on acrylic resin by diluted concentrations of sodium hypochlorite and Ricinus communis solutions.

PURPOSE: To verify whether 0.1% and 0.2% sodium hypochlorite (NaOCl), and 8% Ricinus communis (RC) were able to remove denture biofilm without causing deleterious effects to acrylic resin. BACKGROUND: Previous data show that denture cleansers are effective in reducing biofilm; however, they can change acrylic resin properties. METHODS: In a crossover trial, 47 denture wearers brushed and soaked their dentures (20 min/14 d): control, 0.85% saline; SH1, 0.1% NaOCl; SH2, 0.2% NaOCl and RC. Denture biofilm on the intaglio surface was stained, photographed and quantified (Image Tool® ). Furthermore, 80 rectangular and 80 disc-shaped specimens (Lucitone 550) were assigned into tested solutions (n = 20), simulating 5 years of daily short immersions (20 minutes). A colorimeter and the National Bureau of Standards units (NBS) determined colour data (ΔE). Surface roughness and flexural strength were measured using rugosimeter and universal testing machine, respectively. Data were compared by the Friedman test (α = .05) followed by Wilcoxon, corrected by Bonferroni (α = .005) (clinical) and Kruskal-Wallis followed by the Dunn test (α = .05) (laboratorial). RESULTS: SH2 (MR=1.77) showed lower biofilm coverage; SH1 (MR = 2.37) and RC (MR = 2.74) presented intermediated values. RC (1.10 [0.96:1.75]) revealed higher colour alteration than SH1 (0.71 [0.62:0.80]) and SH2 (0.74 [0.58:0.85]); however, NBS classified all solutions as "trace" (0.0-0.5). There was no statistical significance for surface roughness (P = .760) and flexural strength (P = .547). CONCLUSIONS: The 0.2% NaOCl showed the best clinical performance and did not cause adverse effects on acrylic resin on laboratory analyses.

Phase 1 clinical trial on the effect of palatal brushing on denture stomatitis.

PURPOSE: This study aimed to assess the efficacy of palatal brushing in the treatment of denture stomatitis. MATERIALS AND METHODS: After screening 143 individuals with a potential diagnosis of denture stomatitis, 48 patients (mean age: 66.0 ± 11.2 years) were enrolled in a two-center phase 1 clinical trial with a one-group pretest/posttest design. The intervention of interest was manual palatal brushing after each meal and before bedtime. Clinical and microbiologic examinations were performed at baseline and 1 and 3 months after treatment. Additional data were obtained using a validated questionnaire. The primary and secondary outcomes were the remission of denture stomatitis and diminution of Candida colony-forming units (CFUs), respectively. Descriptive and nonparametric statistical tests were conducted to analyze the data. RESULTS: At the 3-month follow-up, denture stomatitis was completely cured in 10.4% of the participants, and 70.8% of denture wearers showed improvement in the clinical signs of denture stomatitis. There was a significant reduction in the area and severity of the palatal inflammation (P < .0001). The effect size ranged from medium to large (0.34 to 0.54) depending on the classification used for the diagnosis of denture stomatitis. A significant reduction in the number of Candida CFUs isolated from the palatal mucosa and dentures (P ≤ .05) was observed. CONCLUSIONS: The results of this study suggest that palatal brushing is an effective treatment of denture stomatitis.