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Purpose: To compare the influence of surface roughness and accelerated aging on the mechanical properties of polymer-based and ceramic CAD/CAM materials.Materials and Methods: Three polymers (Lava Ultimate [LVU], VITA ENAMIC [ENA], and Shofu Block HC [SFB]) and one ceramic (IPS Empress CAD [EMP]) were selected for this study. The specimens were treated with the aim of measuring surface roughness (Ra [mm]) and its influence on the mechanical properties. The treatments were: polishing (POL); etching with 9.6% hydrofluoric acid for 90 seconds (ETC); airborne-particle abrasion with 50-μm aluminum oxide at 2-bar pressure (SBT); and airborne-particle abrasion with 50-μm aluminum oxide at 2-bar pressure plus etching with 9.6% hydrofluoric acid (SAC) for 90 seconds. Before and after the accelerated aging (AA) protocol (30,000 cycles, 5°C and 55°C), the specimens were subjected to the 3-point bending test. The data were analyzed with two-way and three-way ANOVA and post hoc Tukey test (P < .05).Results: The surface roughness ranged from 0.24 μm to 1.96 μm, with statistically significant differences (P < .05). The highest surface roughness, in descending order, was exhibited by: LVU > SFB > EMP > ENA. The AA demonstrated an influence on the flexural strength of LVU, ENA, and SFB. The surface treatment did not affect the flexural moduli of the materials tested. The LVU and SFB showed decreased moduli of resilience after the AA; however, modulus of resilience was not influenced by surface treatment.Conclusion: The polymer-based materials were affected by AA. In addition, surface treatment could jeopardize their mechanical properties in certain conditions. [ABSTRACT FROM AUTHOR]

CD4+Foxp3+Tregs maintain immune homeostasis, but distinct mechanisms underlying their functional heterogeneity during infections are driven by specific cytokine milieu. Here we show that MyD88 deletion in Foxp3+ cells altered their function and resulted in increased fungal burden and immunopathology during oral Candida albicans (CA) challenge. Excessive inflammation due to the absence of MyD88 in Tregs coincided with a reduction of the unique population of IL-17A expressing Foxp3+ cells (Treg17) and an increase in dysfunctional IFN-γ+/Foxp3+ cells (TregIFN-γ) in infected mice. Failure of MyD88-/- Tregs to regulate effector CD4+ T cell functions correlated with heightened levels of IFN-γ in CD4+ T cells, as well as increased infiltration of inflammatory monocytes and neutrophils in oral mucosa in vivo. Mechanistically, IL-1β/MyD88 signaling was required for the activation of IRAK-4, Akt, and mTOR, which led to the induction and proliferation of Treg17 cells. In the absence of IL-1 receptor signaling, Treg17 cells were reduced, but IL-6-driven expansion of TregIFN-γ cells was increased. This mechanism was physiologically relevant during Candida infection in aged mice, as they exhibited IL-1 receptor/MyD88 defect in Foxp3+ cells, loss of p-mTORhighTreg17 cells and reduced levels of IL-1β in oral mucosa, which coincided with persistent tongue inflammation. Concurrent with Treg dysfunction, aging was associated with increased CD4+ T cell hyperactivation and heightened levels of IL-6 in mice and humans in oral mucosa in vivo. Taken together, our data identify IL-1β/MyD88/Treg axis as a new component that modulates inflammatory responses in oral mucosa. Also, dysregulation of this axis in an aging immune system may skew host defense towards an immunopathological response in mucosal compartments. [ABSTRACT FROM AUTHOR]

Purpose: This cross-sectional study was performed to determine whether an association exists between the width of keratinized mucosa and the health of implant-supporting tissues. Materials and Methods: Data on 200 dental implants were collected. Periodontal parameters measured included Plaque Index, Gingival Index, width of keratinized mucosa, thickness of keratinized mucosa, radiographic bone level, and bleeding on probing. Statistical analysis was accomplished with the t test, Wilcoxon rank sum test, and logistic and linear regression models. Significance was established when P was less than .05. Results: The mean Gingival Index score, Plaque Index score, and radiographic bone loss were significantly higher for those implants with a narrow zone (< 2 mm) of keratinized mucosa. Implants with a narrow zone of keratinized mucosa also were more likely to bleed upon probing, even after adjusting for Plaque Index, smoking, thickness of the gingiva, and time since implant placement (adjusted odds ratio, 2.37; 95% confidence interval, 1.04 to 5.83). Significant independent association also was found between the width of keratinized mucosa and radiographic bone loss in favor of wider zone of keratinized mucosa. Conclusion: Increased width of keratinized mucosa around implants is associated with lower mean alveolar bone loss and improved indices of soft tissue health. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the machinability of four CAD/CAM materials (n = 13) assessed by brittleness index, Vickers hardness, and fracture toughness and interaction among such mechanical properties. The materials selected in this in vitro study are Feldspathic ceramic [FC], Lithium-disilicate glass ceramic [LD], leucite-reinforced glass ceramic [LR], and nanofilled resin material [RN]. Slices were made from the blocks following original dimensions 14 x 12 x 3 mm (L x W x H), using a precision slow-speed saw device and then surfaces were regularized through a polishing device. Brittleness index and fracture toughness were calculated by the use of specific equations for each one of the properties. The Vickers hardness was calculated automated software in the microhardness device. One-way Anova and Pearson's correlation were applied to data evaluation. LD obtained the highest values for brittleness index and was not significantly different from FC. LR presented statistically significant difference compared with RN, which had the lowest mean. Vickers hardness showed LD with the highest average, and no statistical difference was found between FC and LR. RN presented the lowest average. Fracture toughness showed FC and LR not statistically different from each other, likewise LD and RN. The brittleness index, considered also as the machinability of a material, showed within this study as positively dependent on Vickers hardness, which leads to conclusion that hardness of ceramics is related to its milling capacity. In addition, fracture toughness of pre-sintered ceramics is compared to polymer-based materials. [ABSTRACT FROM AUTHOR]

ALS gene expression was studied in the hyposalivatory rat model of oral candidiasis and in clinical specimens collected from HIV-positive patients to assess similarities in expression patterns between the model system and clinical isolates. Two Candida albicans strains, SC5314 and OY-2-76, were used in the rat model system and infection progressed for 3 or 5 days. The strains produced similar oral lesions at 3 days. At 5 days, strain OY-2-76 produced more superficial lesions containing relatively more yeast forms compared to invasive hyphal forms observed for strain SC5314. For all infections, the most severe lesions were observed on the tongue and gingiva overlying the mandible. ALS transcripts were easier to detect by RT–PCR later in infection and under other conditions where more fungal cells were present. Expression of ALS1 , ALS2 , ALS3 and ALS4 was observed in rats infected for 3 days with ALS5 and ALS9 transcripts detected after 5 days of infection. Expression of ALS6 was observed in a single specimen from a 5-day infection while ALS7 transcript was never found. Expression of all ALS genes was observed in oral clinical material collected from HIV-positive patients although ALS6 and ALS7 transcripts required an extra PCR amplification step to be detected. Overall, the patterns of ALS gene expression were similar between the rat model and human clinical specimens, suggesting that the model would be useful for studying the phenotype of alΔ/alΔ mutant strains. [ABSTRACT FROM AUTHOR]

Purpose: There is a burgeoning recognition and interest in the potential of probiotics in the treatment and prevention of oral candidiasis associated with the use of dentures. Our aim was to investigate if commercially available over-the-counter probiotics can influence the ability of Candida albicans to form biofilms, which is considered a hallmark of the initiation and progression of oral candidiasis. Methods: We conducted a 2x5 factorial in vitro study to culture C. albicans on denture strips and challenge with one of the following four commercially available probiotics in bacterial or cell-free supernatant form: Accuflora®, Align®, Culturelle® and Sustenex®. C. albicans biofilm formation was studied in triplicates in all factorial combinations of the study and assessed qualitatively with fluorescence microscopy and quantitatively with tetrazolium salt (XTT) reduction assay. Quality control measures included determination of coefficient of variation, Bland Altman plots and Pittman's test. Results were analyzed using two-way analysis of variance (ANOVA) with pairwise post-hoc Scheffe's tests. Results: Our experimental conditions passed the quality control checks. Two-way ANOVA results indicated that cell-free supernatants provided a stronger and significant inhibitory effect on biofilm formation than their bacterial counterparts (2-way ANOVA p=3.8×10-6). Further, Lactobacillus-containing probiotic formulations (Accuflora® and Culturelle®) significantly reduced biofilm formation especially in supernatant form. Conclusion: Commercially available probiotics that contain Lactobacilli species interfere with the in vitro ability of C. albicans to form biofilms on dentures. The mechanistic and clinical implications of our results need to be addressed by larger in vivo studies. [ABSTRACT FROM AUTHOR]

CD4 + Foxp3 + T regs maintain immune homeostasis, but distinct mechanisms underlying their functional heterogeneity during infections are driven by specific cytokine milieu. Here we show that MyD88 deletion in Foxp3 + cells altered their function and resulted in increased fungal burden and immunopathology during oral Candida albicans (CA) challenge. Excessive inflammation due to the absence of MyD88 in T regs coincided with a reduction of the unique population of IL-17A expressing Foxp3 + cells (T reg 17) and an increase in dysfunctional IFN-γ + /Foxp3 + cells (T reg IFN-γ) in infected mice. Failure of MyD88 -/- T regs to regulate effector CD4 + T cell functions correlated with heightened levels of IFN-γ in CD4 + T cells, as well as increased infiltration of inflammatory monocytes and neutrophils in oral mucosa in vivo . Mechanistically, IL-1β/MyD88 signaling was required for the activation of IRAK-4, Akt, and mTOR, which led to the induction and proliferation of T reg 17 cells. In the absence of IL-1 receptor signaling, T reg 17 cells were reduced, but IL-6-driven expansion of T reg IFN-γ cells was increased. This mechanism was physiologically relevant during Candida infection in aged mice, as they exhibited IL-1 receptor/MyD88 defect in Foxp3 + cells, loss of p-mTOR high T reg 17 cells and reduced levels of IL-1β in oral mucosa, which coincided with persistent tongue inflammation. Concurrent with T reg dysfunction, aging was associated with increased CD4 + T cell hyperactivation and heightened levels of IL-6 in mice and humans in oral mucosa in vivo . Taken together, our data identify IL-1β/MyD88/T reg axis as a new component that modulates inflammatory responses in oral mucosa. Also, dysregulation of this axis in an aging immune system may skew host defense towards an immunopathological response in mucosal compartments., (Copyright © 2020 Bhaskaran, Faddoul, Paes da Silva, Jayaraman, Schneider, Mamileti, Weinberg and Pandiyan.)

Purpose: To compare the fracture toughness of four different CAD/CAM materials, (VM) Vitablocs Mark II, (IP) IPS e.max CAD, (LU) LAVA Ultimate, and (VE) Vita Enamic under long thermocycling conditions., Methods: Each type of ceramic block was sectioned into beams (n=9) with dimensions of 14×3×2.5 mm (L × W × H). All four ceramics were submitted to different conditions: the desiccator or distilled water, each for 7 days. The third and fourth conditions involved the specimens being submitted to 60,000 and 120,000 thermocycles in water respectively. The dwelling time was 52 seconds at 5° and 55°C. A three-point bend test with a universal loading machine on notched samples was per-formed. Furthermore, a fractographic analyses was made by scanning electron microscopy (SEM) to determine if any of these conditions influenced the type of fracture. Data were analyzed by two-way ANOVA (α= 0.05)., Results: A significant difference in fracture toughness (P< 0.05) was found among the groups; IP (4.20±1.23) had the highest value followed by VE (2.02±0.39), which did not have a statistically significant difference from LU (1.96±0.42). The lower value and statistical difference for VM was 1.52±0.35. The ceramics performed better after they were hydrated, while the polymer-based materials had the fracture toughness means decreased after the thermocycles., Clinical Significance: A significant difference in fracture toughness (P<0.05) was found among the groups; IP had the highest value followed by VE, which was not statistically significantly different from LU. The ceramics performed better after they were hydrated, while the polymer-based materials had fracture toughness means decreased after thermocycling., Competing Interests: The authors declared no conflict of interest. Study supported in part by CAPES - Brazil as part of the PhD program from the São Paulo State University - UNESP - Araraquara Faculty of Dentistry, grant #99999.008214/201400., (Copyright©American Journal of Dentistry.)

Background: Bio cellulose is a byproduct of sweet tea fermentation known as kombusha. During the biosynthesis by bacteria cellulose chains are polymerized by enzyme from activated glucose. The single chains are then extruded through the bacterial cell wall. Interestingly, a potential of the Kombucha's byproduct bio cellulose (BC) as biomaterial had come into focus only in the past few decades. The unique physical and mechanical properties such as high purity, an ultrafine and highly crystalline network structure, a superior mechanical strength, flexibility, pronounced permeability to gases and liquids, and an excellent compatibility with living tissue that reinforced by biodegradability, biocompatibility, large swelling ratios., Material and Methods: The bio-cellulose film specimens were provided by the R.P Dressel dental materials laboratory, Department of Comprehensive Care, School of Dental Medicine, Case Western Reserve University, Cleveland, US. The films were harvested, washed with water and dried at room temperature overnight. 1wt% of PEG-2000 and 10wt% of NaOH were added into ultrapure water to prepare PEG/NaOH solution. Then bio-cellulose film was added to the mixture and swell for 3 h at room temperature. All bio-cellulose film specimens were all used in the TA Instruments Q500 Thermogravmetric Analyzer to investigate weight percent lost and degradation. The TGA was under ambient air conditions at a heating rate of 10ºC/min., Results and Conclusions: PEG control exhibited one transition with the peak at 380ºC. Cellulose and cellulose/ PEG films showed 3 major transitions. Interestingly, the cellulose/PEG film showed slightly elevated temperatures when compared to the corresponding transitions for cellulose control. The thermal gravimetric analysis (TGA) degradation curves were analyzed. Cellulose control film exhibited two zero order transitions, that indicate the independence of the rate of degradation from the amount on the initial substance. The activation energies for three transitions for cellulose and cellulose/PEG showed increasingly higher values for the transitions at higher temperatures. Key words: TGA, Bio-cellulose, PEG., Competing Interests: Conflict of interest statement:The authors hereby report no conflicts of interest with regards to this work.