Does the application of whitening dentifrices during at-home bleaching affect the bond strength of resin composite to dentin?

AIM: This study aimed to evaluate the effect of using whitening dentifrices during at-home bleaching on the shear bond strength (SBS) of resin composite to dentin, and investigate whether the increased polymerization time would improve SBS. METHODS: Ninety-six bovine incisors were divided into 4 groups of 24, according to the whitening treatment applied as follows: group 1, at-home bleaching + brushing with a regular dentifrice; group 2, at-home bleaching + brushing with a whitening dentifrice containing ozone; group 3, at-home bleaching + brushing with a commercial whitening dentifrice; and group 4 (control), no whitening/brushing treatment. Each group was divided into two subgroups (n = 12) to assess the effect of curing time (20 versus 80 s) on SBS. A self-etch adhesive was bonded to dentin, and after 2-day water storage, SBS was determined. RESULTS: SBS was significantly affected by the whitening treatment (P = 0.03), but increasing the curing time had no significant effect on SBS (P = 0.137). Bond strength in group 1 was comparable to the control group (P > 0.05). The specimens in group 3 displayed significantly lower SBS than either group 4 or group 1 (P > 0.05). No significant difference was observed between the SBS of group 2 compared to any other group (P > 0.05). There was no significant association between the treatment group and failure type (P > 0.05). CONCLUSION: The bonding interface was not negatively influenced by the at-home bleaching procedure. However, using a commercial whitening dentifrice during at-home bleaching produced a significant detrimental effect on SBS. Extending the curing time would have no beneficial effect on adhesion to a whitened dental substrate.

Total antioxidant capacity as a marker of severity of COVID-19 infection: Possible prognostic and therapeutic clinical application.

The pathogenesis of SARS-CoV-2 infection, causative pathogen of the known COVID-19 pandemic is not well clarified. In this regard oxidative stress is one of the topics that need to be investigated. Therefore, the present research was performed to explore the relationship between the oxidant/antioxidant system and COVID-19 exacerbation. Sera were collected from 120 patients with COVID-19 infection and 60 healthy volunteers as the control group. The patient group consisted of 60 cases with mild disease and 60 severely ill patients. Serum levels of total antioxidant capacity (TAC) and nitric oxide (NO) as well as serum activities of the two main antioxidant defense enzymes, superoxide dismutase (SOD) and catalase (CAT), were measured. TAC levels were considerably lower in patients compared with healthy individuals (p < 0.05) and also between patients with mild and severe diseases (p < 0.05). A rather decreasing trend was also found in NO concentration as well as SOD and CAT activity, though, the observed differences were not statistically significant (p > 0.05). These findings suggest that COVID-19 patients may be susceptible to depleted total antioxidant capacity. Moreover, showing such variations in blood samples of infected individuals could be considered as a predictive marker of COVID-19 severity.

The effect of acupressure on fasting blood glucose, glycosylated hemoglobin and stress in patients with type 2 diabetes.

OBJECTIVE: This study aimed to determine the effect of acupressure on stress, fasting blood glucose (FBG) and glycosylated hemoglobin (HBA1C) in patients with type 2 diabetes. METHODS: In this randomized controlled clinical trial, sixty-six diabetic patients who met the inclusion criteria were randomly divided into intervention and sham groups. The intervention group applied self-acupressure to the desired points for a month. The sham group were asked to slightly touch the same points. The DASS-21 and FBG were measured before intervention, 24 h after the intervention for both groups. In addition, HBA1C was measured for both groups before intervention and three months after the beginning of the intervention. Data were analyzed with SPSS 15. RESULTS: Statistical data analysis of 60 patients showed that the mean FBG and the mean stress score of the intervention group reduced significantly after the intervention (p < 0.001) but the mean rate of HBA1C in the intervention group did not differ significantly after the intervention (p = 0.21). CONCLUSION: Acupressure should be considered for diabetic patients to reduce their stress and FBG.

Synergistic influence of mesoporous spinel nickel ferrite on the electrocatalytic activity of nano-structured palladium.

Structure and surface area are critical factors for catalysts in fuel cells. Hence, a spinel nickel ferrite mesoporous (SNFM) is prepared via the solution combustion technique, an efficient and one-step synthesis. Dynamic X-ray analysis has clarified the structural properties of SNFM. The grain size of SNFM is determined to be ∼11.6 nm. The specific surface area (87.69 m2. g-1) of SNFM is obtained via the Brunauer-Emmett-Teller method. The Barrett-Joyner-Halenda pore size distributions revealed that the size of the mesopores in as-synthesized SNFM mainly falls in the size range of 2-16 nm. Scanning electron microscopy studies showed the regularities involved during porous-structure formation. SNFM is employed as the support for nano-structured palladium (PdNS). Field emission scanning electron microscope studies of PdNS-SNFM showed the deposition of PdNS in cavities and on/in the pores of SNFM. The electrochemical surface area obtained for PdNS-SNFM is about 27 times larger than that of PdNS via cyclic voltammetry. The electrochemical studies are utilized to study the features and catalytic performance of PdNS-SNFM in the electro-oxidation of diverse small organic fuels, whereas the electrooxidation of diethylene glycol is reported for first-time.

New Pd/Co-Ni electrocatalysts for formic acid electrooxidation and their fabrication from inorganic precursor [Co0.14Ni1.86(dipic)2(phen)2(H2O)2]·4H2O.

Novel Pd/Co-Ni oxide composites were developed as electrocatalysts for formic acid electro-oxidation as a process that can be utilised in fuel cells and electrochemical sensors. For achieving this goal, the new complex [Co0.14Ni1.86(dipic)2(phen)2(H2O)2]·4H2O (1) was synthesised and used as an inorganic precursor for producing a Co-Ni mixed metal promoter. In the following, palladium nanoparticles were anchored on Co-Ni mixed metal oxides via a reaction of chemical reduction with four different loadings. The electrocatalytic activity of the electrocatalysts was investigated for HCOOH electro-oxidation by electrochemical studies. Compared with single component electrocatalysts, the new electrocatalysts exhibited higher current, improved absorption/desorption of hydrogen, and a higher loading for metal oxides.

Tanacetum parthenium enhances pentobarbital-induced sleeping behaviors.

OBJECTIVE: Sleep disorders are among the most common psychiatric and medical conditions. In the present study, the hypnotic effect of Tanacetum parthenium was studied in mice. MATERIALS AND METHODS: The hydro-alcoholic extract (HAE) of T. parthenium and three fractions of it, namely water fraction (WF), ethyl acetate fraction (EAF), and n-hexane fraction (NHF), were intraperitoneally (ip) administrated to mice 30 min before injection of sodium pentobarbital (30 mg/kg, ip). Then, 30 min after administration of HAE, motor coordination (rota-rod test) was evaluated. Besides, LD50 of HAE was determined and the cytotoxicity of HAE was evaluated in PC12 cells using the MTT assay. RESULTS: HAE 50-200 mg/kg increased the sleeping time. EAF was the only fraction which could prolong the sleep duration and decrease sleep latency. The LD50 value was 4.8 g/kg. The extract induced no cytotoxic effects in PC12 cell line. CONCLUSION: The results suggested that T. parthenium potentiates pentobarbital hypnosis without causing toxic effects. Probably, its effects are mediated by the components present in EAF of this plant.

Catalyst Behavior Analyzed via General Regression Model with the Parameters Depending on a Covariate.

In this work, the catalytic activity of modified glassy carbon electrodes with xPd-yLaNi0.5Fe0.5O3-chitosan as an anodic catalyst for the polymeric fuel cell was investigated with cyclic voltammetry and controlled potential coulometry techniques; x and y are the mass loading of noble metal and mixed oxide, respectively. For the first time, the statistical regression mixed models were used to compare the electrocatalytic ability of nanocomposites in a fuel cell. The nonlinear regression model of y i,j = f(x i , (s j )) + ε i was considered and simulated, where X i is a random variable, s j is a covariate value, ε i is a normal random error variable, and θ is a P-dimensional vector of parameters of the mentioned model. A strategy to make a mixed model was proposed by using the maximum likelihood or mean square error methods. Then, the appropriate linear and nonlinear models were applied to the electrochemical results. The equations of current density vs time were obtained via the fitting and simulation of experimental data at different potentials and mass loadings of components. The amounts of transferred charge during the methanol oxidation were calculated vs time through the integration of mentioned equations at different potentials and mass loadings of components.

Ocular response analyzer parameters in healthy, keratoconus suspect and manifest keratoconus eyes.

BACKGROUND: To evaluate and compare corneal biomechanical indices and their specificity among keratoconus (KC), keratoconus suspect (KCS), and normal eyes (NL) before and after controlling potential confounders. MATERIALS AND METHODS: A total of 160 eyes in three groups were included prospectively: NL, KC, and KCS groups based on clinical examination and topography. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by the ocular response analyzer. CH and CRF were compared between the three groups by analysis of variances test. RESULTS: The three groups consisted of 80 NL, 48 KC, and 32 KCS eyes. The mean CH measured was 10.4 ± 1.25, 7.83 ± 1.28 and 10.17 ± 1.80 mm Hg in NL, KC and KCS eyes, respectively. The mean CRF was 10.23 ± 1.75, 6.5 ± 1.63 and 9.98 ± 2.00 mm Hg in NL, KC and KCS eyes, respectively. Mean CH and CRF were significantly different between the NL and KC (P < 0.05); however after controlling for central corneal thickness and sex; there was no significant difference between NL and KCS (P > 0.05). CONCLUSION: CH and CRF can be helpful in differentiating KC from NL eyes; however, they are not valuable for detecting KCS that is the main concern for refractive surgery. Future studies focusing on more accurate tests for identifying KCS, using a consistent grading scale for defining KC and KCS are still warranted.