Effect of desensitizing agents on the resin bond strength to sound dentin.

This study aimed to evaluate the effect of dentin hypersensitivity treatments on immediate and long-term shear bond strength (SBS) of composite restorations. Ninety non-carious extracted human molars were cut to expose dentin, which was embedded in acrylic resin, and randomly divided into three groups (n = 30/group) according to surface treatment: 1) no treatment (C and C*; control); 2) silver diamine fluoride with potassium iodide (SDF/KI and SDF/KI*; Riva Star); and 3) nano-hydroxyapatite (nHAp and nHAp*; PrevDent). The specimens were etched through the etch-and-rinse technique, followed by universal adhesive application and resin composite cylinders (2.38 mm in diameter × 3.5 mm high). The SBS was tested immediately (24 h after the restoration) and after thermocycling (*) (5000 cycles, 5 °C to 55 °C) at a 0.5 mm/min crosshead speed using a universal testing machine. A stereomicroscope was used to evaluate the mode of failure, and representative scanning electron microscopy (SEM) images were also acquired. Data normality was verified, and two-way ANOVA and Tukey's post hoc tests were performed for multiple comparisons (α = 0.05). The control group presented the highest SBS (27.10 MPa), while SDF/KI* had the lowest values (6.87 MPa). nHAp-based desensitizer exhibited higher SBS than SDF/KI for both immediate (22.6 MPa) and thermocycled (19.03 MPa) conditions. No intragroup difference was evidenced between immediate and thermocycled samples for any group. Most specimens for the C and nHAp groups presented mixed failure, while the SDF/KI groups presented comparable adhesive and mixed failures. The SBS of adhesive restorations after the application of desensitizing agents is material dependent, where SDF/KI reduces SBS values below the acceptable minimum bond strength, while the nHAp application meets the minimally required bond strength.

Incorporation of Arginine to Commercial Orthodontic Light-Cured Resin Cements-Physical, Adhesive, and Antibacterial Properties.

(1) Background: The amino acid arginine is now receiving great attention due to its potential anti-caries benefits. The purpose of this in vitro study was to evaluate the shear bond strength (SBS), ultimate tensile strength (UTS), and antimicrobial potential (CFU) of two arginine-containing orthodontic resin cements. (2) Methods: Forty bovine incisors were separated into four groups (n = 10): Orthocem, Orthocem + arginine (2.5 wt%), Transbond XT, and Transbond XT + arginine (2.5 wt%). The brackets were fixed to the flat surface of the enamel, and after 24 h the SBS was evaluated using the universal testing machine (Instron). For the UTS test, hourglass samples (n = 10) were made and tested in a mini-testing machine (OM-100, Odeme). For the antibacterial test (colony forming unit-CFU), six cement discs from each group were made and exposed to Streptococcus mutans UA159 biofilm for 7 days. The microbiological experiment was performed by serial and triplicate dilutions. The data from each test were statistically analyzed using a two-way ANOVA, followed by Tukey's test (α = 0.05). (3) Results: The enamel SBS mean values of Transbond XT were statistically higher than those of Orthocem, both with and without arginine (p = 0.02033). There was no significant difference in the SBS mean values between the orthodontic resin cements, either with or without arginine (p = 0.29869). The UTS of the Transbond XT was statistically higher than the Orthocem, but the addition of arginine at 2.5 wt% did not influence the UTS for either resin cement. The Orthocem + arginine orthodontic resin cement was able to significantly reduce S. mutans growth, but no difference was observed for the Transbond XT (p = 0.03439). (4) Conclusion: The incorporation of arginine to commercial orthodontic resin cements may be an efficient preventive strategy to reduce bacterial growth without compromising their adhesive and mechanical properties.

Correction: Trans,trans-farnesol, an antimicrobial natural compound, improves glass ionomer cement properties.

[This corrects the article DOI: 10.1371/journal.pone.0220718.].

Trans,trans-farnesol, an antimicrobial natural compound, improves glass ionomer cement properties.

A series of experiments were conducted to characterize a novel restorative material. We explored the effect on biological, physical and chemical properties of glass ionomer cement (GIC) adding-the naturally occurring tt-farnesol (900 mM). Two groups were accomplished for all assays: GIC+tt-farnesol and GIC (control). Biological assays: 1) agar diffusion against some cariogenic bacteria; 2) S. mutans biofilm formation and confocal laser scanning microscopy-CLSM. 3) gtfB, gtfC, gtfD, gbpB, vicR, and covR expression; 4) MTT and microscopic morphology. Physical properties assays: 1) roughness; 2) hardness; 3) compressive strength and 4) diametral tensile strength. Chemical assay: Raman spectroscopy. The adding of tt-farnesol to GIC led to larger zones of inhibition (p<0.05), biofilms with a short-term reduction in bacterial viability but similar biomass (p>0.05). Polysaccharides levels increased over time, similarly over groups (p>0.05). Viable and non-viable S. mutans were seen on the specimens' surface by CLSM but their virulence was not modulated by tt-farnesol. The tt-farnesol increased the HaCaT cell viability without impact on compressive and diametral tensile strength and roughness although the hardness was positively affected (p<0.05). Raman confirmed the presence of tt-farnesol. The incorporation of tt-farnesol into GIC inhibited the growth of cariogenic bacteria but had a little effect on the composition, structure and physiology of the biofilm matrices. Also, the tt-farnesol increased the hardness and the biocompatibility of the GIC, not influencing negatively other physical properties of the restorative material.

A novel Triclosan Methacrylate-based composite reduces the virulence of Streptococcus mutans biofilm.

The use of antimicrobial monomers, linked to the polymer chain of resin composites, is an interesting approach to circumvent the effects of bacteria on the dental and material surfaces. In addition, it can likely reduce the incidence of recurrent caries lesions. The aim of this study was to evaluate the effects of a novel Triclosan Methacrylate (TM) monomer, which was developed and incorporated into an experimental resin composite, on Streptococcus mutans (S. mutans) biofilms, focusing on the analyses of vicR, gtfD, gtfC, covR, and gbpB gene expression, cell viability and biofilm characteristics. The contact time between TM-composite and S. mutans down-regulated the gbpB and covR and up-regulated the gtfC gene expression, reduced cell viability and significantly decreased parameters of the structure and characteristics of S. mutans biofilm virulence. The presence of Triclosan Methacrylate monomer causes harmful effects at molecular and cellular levels in S. mutans, implying a reduction in the virulence of those microorganisms.

Rubbing ethanol and time of use: critical factors compromising latex gloves structure / Desinfecção com etanol e tempo de uso: fatores críticos que comprometem a estrutura das luvas de látex

Abstract Introduction Personal protective equipment is mandatory to protect patients and professionals from diseases, especially in the dental environment. The risk of gloves micro-perforations is imminent when using sharp instruments or cleaning them up during lengthy clinical procedures. Objective This study evaluated the integrity of sterile and non-sterile gloves before clinical use and clarified whether friction with disinfectant solution modifies surface morphology and integrity. Material and method Samples of gloves from four different brands were divided into two groups: (1) Sterile surgical gloves (n=260) and (2) Non-sterile gloves (n=260). They were scissored and placed in Ostby's arch so that three solutions - distilled water, ethanol 70°, ethanol 96° - were rubbed with a cotton swab. After 30s, 5, 10, and 15 minutes of solution rubbing, samples were verified by a Scanning Electron Microscope. The pore sizes were measured by Image J software. Result Regardless of the brands, all gloves have been significantly affected by solutions and assessment periods. In general, remarkable changes were evident with ethanol 70° and 96°, and higher pore diameters were observed compared to distilled water. Conclusion Rubbing disinfectant solutions increases gloves' pores sizes, and time negatively influenced its quality.

Resumo Introdução Para proteger pacientes e profissionais de doenças, o uso de equipamentos de proteção individual é obrigatório, principalmente no ambiente odontológico. O risco de microperfurações das luvas é iminente ao usar instrumentos cortantes ou na tentativa de limpar as luvas durante longos procedimentos clínicos. Objetivo Este estudo avaliou a integridade das luvas cirúrgicas e de procedimento antes do uso clínico e esclareceu se o atrito com a solução desinfetante modifica a morfologia e integridade da superfície. Material e método Amostras de luvas de quatro marcas diferentes foram divididas em dois grupos: (1) Luvas cirúrgicas (n = 260) e (2) Luvas descartáveis não estéreis (n = 260). As luvas foram cortadas e colocadas em arco de Ostby, de modo que três soluções - água destilada, etanol 70 °, etanol 96 ° foram esfregadas com um cotonete. Após 30s, 5, 10 e 15 minutos de fricção das soluções, as amostras foram verificadas utilizando um microscópio eletrônico de varredura. Os tamanhos dos poros foram medidos pelo software Image J. Resultado Independentemente das marcas, todas as luvas foram significativamente afetadas por soluções e períodos de avaliação. Em geral, maiores alterações foram evidenciadas com o uso do etanol 70° e 96°, e maiores diâmetros dos poros foram observados quando comparados à água destilada. Conclusão Esfregar soluções desinfetantes aumenta o tamanho dos poros das luvas e o tempo influenciou negativamente sua qualidade.