Effect of effervescent tablets on removable partial denture hygiene.

PURPOSE: To evaluate the effectiveness of five alkaline peroxide-based effervescent tablets in reducing both biofilms and the food layer adhered on the cobalt-chromium surface. METHODS: Cobalt-chromium metal alloy specimens were contaminated with Candida albicans, Candida glabrata, Streptococcus mutans and Staphylococcus aureus. After biofilm maturation, the specimens were immersed in Polident 3 Minute, Polident for Partials, Efferdent, Steradent, Corega Tabs or distilled water (control). Residual biofilm rates were determined by colony forming units counts and biofilm biomass. In parallel, to investigate the denture cleaning capability of effervescent tablets, artificially contaminated removable partial dentures were treated with each cleanser. Data were analyzed by Kruskal-Wallis followed by Dunn post hoc test or ANOVA followed by Tukey post hoc test (α= 0.05). RESULTS: None of the hygiene solutions reduced C. albicans biofilm. Efferdent and Corega Tabs promoted reduction of C. glabrata biofilm, while Steradent was favorable against S. aureus biofilm. For S. mutans, lower biofilm rates were observed after immersion in Polident for Partials and Steradent. The effervescent tablets showed good cleaning performance, removing an artificial layer with carbohydrates, proteins, and fats, however, they were not effective in removing aggregated mature biofilm. CLINICAL SIGNIFICANCE: The different effervescent tablets presented favorable antimicrobial activity against C. glabrata, S. mutans and S. aureus on cobalt-chromium surfaces and showed cleaning capability. However, for an appropriate biofilm control, a complementary method should be evaluated since none of the peroxide-based solutions reduced C. albicans biofilms or substantially removed aggregated biofilm.

Effects of a high-fat diet on the bone structure of Wistar rats: a systematic review.

CONTEXT: Saturated fats found in diets known as high-fat, cafeteria, or Western diets appear to have a negative effect on bone structure; however, few studies have focused on investigating this association, and the data available in the literature remain controversial. OBJECTIVE: The aim of the current review was to investigate the effects of a high-fat dietary intake on the bone structure of Wistar rats. DATA SOURCES: A search for articles was carried out in the Pubmed/MEDLINE, Web of Science, Embase, and Scopus databases. DATA EXTRACTION: In total, 447 articles were found in the initial search; 5 articles were included in the systematic review, after application of the exclusion criteria. DATA ANALYSIS: The review was guided by the PICOS strategy and based on the PRISMA protocol for animal reviews. CONCLUSION: High-fat diets appear to affect bone structure of Wistar rats. Diet composition and exposure time are the factors determining the strength of the effect.

Preliminary study on a novel dedicated plate for iliac fractures in dogs.

INTRODUCTION: The aim of this study was to describe and evaluate a novel plate designed specifically for the canine ilium using finite element methods. The cranial portion of the plate had an elliptical shape and contained nine screw holes. The caudal portion of the plate was triangular with three screw holes. Four and three screws were used at the cranial (screw 1 to 4) and caudal (screw 5 to 7) segment of the plate. Finite element models of the plate and canine pelvis were created. A load of 300 N was applied on the femur-hip joint contact area. Values of Von Mises Stress on the plate, screws and the maximum and minimum main stresses in the bone were used to capture the mechanical factors in this study. RESULTS: The novel implant had a plate stress of 51.9 megapascals (MPa) with higher stress in the dorsal part of the plate. Screws 2 and 4 showed similar stress values of 17.3 MPa. Screws 1 and 3 were the most loaded (51.9 MPa and 75 MPa, respectively). Screws 5, 6, and 7 showed similar dissipation and stress values (21.55 MPa). There was traction force in the dorsal region of the pubis and compression in the ventral part, with dissipation and values of 15.4 MPa and 23.9 MPa, respectively, acquiring balance between them. CONCLUSION: The novel plate is potentially applicable and specifically suitable for iliac fractures in dogs. The screws distribution modeled proved itself strategical since the simulated stresses were evenly distributed throughout the implant construct.

Effect of local hygiene protocols on denture-related stomatitis, biofilm, microbial load, and odor: A randomized controlled trial.

STATEMENT OF PROBLEM: Denture stomatitis affects complete denture wearers and is frequently treated with antifungals drugs, as well as treating the denture with sodium hypochlorite. Whether the limitations of these treatments can be overcome with local hygiene protocols that do not damage the denture materials or adversely affect the patient is unclear. PURPOSE: The purpose of this randomized controlled trial was to evaluate the effect of denture hygiene protocols on complete denture wearers with denture stomatitis. MATERIAL AND METHODS: For this randomized, double-blind controlled clinical trial, 108 participants were assigned to parallel groups: 0.25% sodium hypochlorite (positive control) 0.15% Triclosan, denture cleaning tablets, or denture cleaning tablets plus gingival cleaning tablets. The participants were instructed to brush the dentures and the palate and immerse the denture in the solutions. The outcomes of denture stomatitis remission, biofilm removal, decrease of microbial load (colony-forming units), and odor level of the mouth and denture were measured at baseline and after 10 days. Descriptive analyses were used for sociodemographic characterization of the participants; the Pearson chi-square test was used to compare participant frequency with different degrees of denture stomatitis. The data were not normally distributed (Shapiro-Wilks test) or homogeneous (Levene test). So, the Kruskal-Wallis and Dunn post hoc tests and Wilcoxon test were used to compare the effects of solutions and time on the variables (α=.05). RESULTS: The frequency of the highest to lowest denture stomatitis scores was significantly different for the 0.15% Triclosan and denture cleaning tablets groups. No significant difference was found among the groups in terms of denture stomatitis scores, biofilm, or colony-forming unit count of Candida spp. or C. albicans and S. mutans; a significant reduction was found in these parameters. The 0.25% sodium hypochlorite and 0.15% Triclosan treatments caused a significant reduction in Gram-negative microorganisms; these 2 protocols, and the denture cleaning tablets showed a significant reduction in Staphylococcus spp.; all protocols had similar effects. Only the S. mutans count of the palate decreased after 10 days. The odor level of the mouth and the denture was not significantly different (P=.778). CONCLUSIONS: The evaluated protocols can be recommended for the hygiene of complete dentures, since they were effective for all the variables studied.

Effectiveness of Oil-Based Denture Dentifrices-Organoleptic Characteristics, Physicochemical Properties and Antimicrobial Action.

Denture dentifrices must be effective and not deleterious to prosthetic devices. This study formulated and evaluated dentifrices based on oils of Copaifera officinalis, Eucalyptus citriodora, Melaleuca alternifolia, Pinus strobus, and Ricinus communis. Organoleptic characteristics (appearance, color, odor, taste), physicochemical properties (pH, density, consistency, rheological, abrasiveness, weight loss, and surface roughness) and antimicrobial (Hole-Plate Diffusion-HPD)/anti-biofilm (Colony Forming Units-CFU) action against Staphylococcus aureus, Streptococcus mutans, and Candida albicans were evaluated. Formulations were compared with water (negative control) and a commercial dentifrice (positive control). The data were analyzed by Kruskal-Wallis and Dunn tests (α = 0.05). The organoleptic and physicochemical properties were adequate. All dentifrices promoted weight losses, with high values for C. officinalis and R. communis, and an increase in surface roughness, without differing from each other. For antimicrobial action, C. officinalis and E. citriodora dentifrices were similar to positive control showing effectiveness against S. mutans and C. albicans and no dentifrice was effective against S. aureus; regarding the anti-biofilm action, the dentifrices were not effective, showing higher CFU counts than positive control for all microorganisms. The dentifrices presented satisfactory properties; and, although they showed antimicrobial action when evaluated by HPD, they showed no effective anti-biofilm action on multispecies biofilm.

Exercise Counterbalances Rho/ROCK2 Signaling Impairment in the Skeletal Muscle and Ameliorates Insulin Sensitivity in Obese Mice.

Physical exercise is considered a fundamental strategy in improving insulin sensitivity and glucose uptake in skeletal muscle. However, the molecular mechanisms underlying this regulation, primarily on skeletal muscle glucose uptake, are not fully understood. Recent evidence has shown that Rho-kinase (ROCK) isoforms play a pivotal role in regulating skeletal muscle glucose uptake and systemic glucose homeostasis. The current study evaluated the effect of physical exercise on ROCK2 signaling in skeletal muscle of insulin-resistant obese animals. Physiological (ITT) and molecular analysis (immunoblotting, and RT-qPCR) were performed. The contents of RhoA and ROCK2 protein were decreased in skeletal muscle of obese mice compared to control mice but were restored to normal levels in response to physical exercise. The exercised animals also showed higher phosphorylation of insulin receptor substrate 1 (IRS1 Serine 632/635) and protein kinase B (Akt) in the skeletal muscle. However, phosphatase and tensin homolog (PTEN) and protein-tyrosine phosphatase-1B (PTP-1B), both inhibitory regulators for insulin action, were increased in obesity but decreased after exercise. The impact of ROCK2 action on muscle insulin signaling is further underscored by the fact that impaired IRS1 and Akt phosphorylation caused by palmitate in C2C12 myotubes was entirely restored by ROCK2 overexpression. These results suggest that the exercise-induced upregulation of RhoA-ROCK2 signaling in skeletal muscle is associated with increased systemic insulin sensitivity in obese mice and further implicate that muscle ROCK2 could be a potential target for treating obesity-linked metabolic disorders.

Bacteriophage Cocktail-Mediated Inhibition of Pseudomonas aeruginosa Biofilm on Endotracheal Tube Surface.

Although different strategies to control biofilm formation on endotracheal tubes have been proposed, there are scarce scientific data on applying phages for both removing and preventing Pseudomonas aeruginosa biofilms on the device surface. Here, the anti-biofilm capacity of five bacteriophages was evaluated by a high content screening assay. We observed that biofilms were significantly reduced after phage treatment, especially in multidrug-resistant strains. Considering the anti-biofilm screens, two phages were selected as cocktail components, and the cocktail's ability to prevent colonization of the endotracheal tube surface was tested in a dynamic biofilm model. Phage-coated tubes were challenged with different P. aeruginosa strains. The biofilm growth was monitored from 24 to 168 h by colony forming unit counting, metabolic activity assessment, and biofilm morphology observation. The phage cocktail promoted differences of bacterial colonization; nonetheless, the action was strain dependent. Phage cocktail coating did not promote substantial changes in metabolic activity. Scanning electron microscopy revealed a higher concentration of biofilm cells in control, while tower-like structures could be observed on phage cocktail-coated tubes. These results demonstrate that with the development of new coating strategies, phage therapy has potential in controlling the endotracheal tube-associated biofilm.

Adaptation accuracy of milled lithium disilicate crowns: A 2D and 3D microCT analysis.

OBJECTIVE: Evaluate the effects of the scanning techniques and the crystallization in the internal and marginal adaptation of milled lithium disilicate crowns by two techniques computer microtomography analysis. MATERIALS AND METHODS: Sixteen polyurethane teeth prepared for a complete crown were divided into two groups according to the scanner method (n = 8): indirect (IND), dental stone models were scanned with laser-surface scanner, and direct (DIR), digital typodont creates with an intraoral scanner. Internal and marginal gap were evaluated by micro-computed tomography (microCT). The replica technique (RT) was applied for analysis of total volume (TV) and marginal volume (MV) gap in microCT. The data showed normal distribution (Shapiro-Wilk test). One-way ANOVA (scanner techniques) with repeated measures (crystallization) was performed. Multiple comparisons were performed with Bonferroni adjustment (α = .05). RESULTS: The axial gap showed a significant difference between the times (P = .017) for lower values after crystallization. The vertical marginal gap presented a significant difference in times for higher value after crystallization (P = .001). The marginal horizontal gap IND was greater than DIR after crystallization (P = .001) and IND before lower than after crystallization. For TV was not significant difference and MV in DIR was reduction (P = .002) after crystallization. CONCLUSION: Crystallization changes the relationship between the crown and tooth, reducing internal gap and preventing the adequate fit in indirect and direct scanning. CLINICAL SIGNIFICANCE: The measure gap under technological methodology is useful for adjust clinical parameters prosthetic in the CAD/CAM and the applicability of the new possibilities of analysis.

In vitro evaluation of the effectiveness of alkaline peroxide solutions in reducing the viability of specific biofilms.

PURPOSE: To evaluate in vitro the effectiveness of eight different cleansers containing alkaline peroxide against yeast [Candida albicans (Ca) and Candida glabrata (Cg) ], Gram-negative bacteria [Escherichia coli (Ec) and Pseudomonas aeruginosa (Pa) ], and Gram-positive bacteria [ Bacillus subtilis (Bs), Enterococcus faecalis (Ef), Staphylococcus aureus (Sa), and Streptococcus mutans (Sm) ]. METHODS: Denture base acrylic resin specimens (Lucitone 550; 1264 denture base acrylic resin specimens) were obtained from a circular metal matrix (15 x 3 mm) and sterilized with microwave irradiation (650 W, 6 minutes). The specimens were contaminated with 106 CFU/mL suspension of yeasts and 108 CFU/mL suspensions of Gram-positive and -negative bacteria. The contaminated specimens were incubated (37°C/48 hours) and immersed (short cycle) in a stainless steel basket placed in a beaker. The beaker contained one of the following cleanser solutions, which were prepared and used according to the manufacturers' instructions (n=10): PBS (positive control, C), Fixodent (FI), Medical Interporous (MI), Kukident (KU), Efferdent Plus (EF), Equate (EQ), Kroger (KR), Kirari (KI), and Corega Tabs (CT). Reduction in the viability of microorganisms was evaluated through counting of Colony Forming Units (CFU/mL), metabolic activity (XTT), and cell viability by epifluorescence microscopy (EM) analyses. For counting CFU, the specimens (n=10 of each group) were washed and immersed in Letheen medium, from which aliquots were obtained and seeded into selective solid culture media. After incubation (37°C, 24 hours), the colonies were counted (CFU/mL). The metabolic activity of microorganisms was measured using XTT reduction assay (n=5). For EM analysis, the specimens (n= 2 of each group) were stained (Live/Dead BacLight), and the images were analyzed in terms of biofilm areas (total and living cells). Data were processed and analyzed by Wilcoxon, Mann Whitney and Kruskal-Wallis tests followed by Dunn test (α= 0.05). RESULTS: Significant differences were found between the experimental groups and C for the evaluated microorganisms. MI was the most effective for yeasts; this cleanser reduced the metabolic activity, viability, and total counts of both yeasts evaluated. All cleansers reduced the total counts of Gram-negative microorganisms, except CT for Pa. For Gram-negative bacteria, KR, CT, EF, and EQ significantly reduced the metabolic activity of Ec but did not remove all dead cells. FI and MI significantly reduced the metabolic activity of Pa, and the latter also removed the dead cells of Pa. FI and MI showed improved results against all Gram-positive bacteria. Both cleansers significantly decreased the metabolic activity of all bacterial species and reduced the viability of Sa, Ef, and Bs. MI also reduced the biofilm aggregates of Sm. CLINICAL SIGNIFICANCE: This study concluded that under the experimental conditions tested, denture cleansers can be used as coadjutants in denture cleaning. The evaluated cleansers exhibited disinfectant action, thereby preventing the proliferation of microorganisms on the denture surface and reducing the risk of opportunistic infections.

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.

A Digital Image Correlation Analysis of Strain Generated by 3-Unit Implant-Supported Fixed Dental Prosthesis: An In Vitro Study.

OBJECTIVE: To evaluate the influence of different veneering materials (porcelain and resin) and implants (short and conventional) in the strain distribution of implant-supported splinted fixed partial dentures (FPDs) using digital image correlation (DIC). MATERIAL AND METHODS: Four polyurethane models were fabricated with resin replicas (first premolar) and short and/or conventional implants replacing the second premolar and first and second molars, according to the following configurations: G1, 2 conventional (second premolar and first molar) and 1 short (second molar) implant; G2, 1 conventional (second premolar) and 2 short (first and second molar) implants; G3, 3 short implants; G4, 3 conventional implants. Porcelain- and resin-veneered splinted FPDs were screwed to the implant abutments. The DIC system was used to calculate strains during application of occlusal load (250 N). RESULTS: Porcelain- and resin-veneered showed similar strain distribution for all groups (P > 0.05). Concentration of compressive strains was higher in G3P and G3R with maximum compressive strains of -1271.50 and -1026.88 µs, respectively. G4 transferred the best strain distribution (porcelain, -275.14 µs; resin, -254.44 µs), followed by G2 (porcelain, -306.79 µs; resin, -310.63 µs). CONCLUSION: The veneering material used did not influence the strain distribution. In addition, conventional implants generate less strain concentration, although the combination of 2 short and 1 conventional implant seems to be a viable plan.

The influence of gender and ethnicity on children's peer collaborations.

Gender and ethnicity are important aspects of children's everyday social relationships, yet little is known about how these social categories influence children's collaborative interactions. In the present study, 322 White (Caucasian) and South Asian boys and girls (mean age, 7.5 years) collaborated in pairs on easy and difficult versions of a model completion task. As expected, girls were less assertive than boys in conversation, yet this relation held only for all-Asian pairs (i.e., an Asian boy and girl in conversation). Also consistent with expectations, levels of conversational affiliation were lowest in cross-ethnic interaction. The influence of gender and ethnicity on conversations did not vary in light of contrasting cognitive demands of the tasks. Results are discussed in relation to work on effective peer collaboration and the potential role of contact in promoting positive ethnic and gender group attitudes.