Evaluation of the effect of various types of fluoride varnishes on color stability of a composite resin

BACKGROUND AND AIM: Fluoride varnish as an extrinsic factor may cause discoloration in tooth-colored restorative materials. This research compared the impact of different fluoride varnishes on color change of a composite restorative material. METHODS: This laboratory experimental study was conducted on 40 specimens of flowable composite resin were divided into four groups based on the brand of applied varnishes (Durashield, Nupro, Fluorilaque, and Profluoride varnishes) (n = 10). Color measuring (ΔE) was performed using the easy shade device and according to Commission Internationale de l’Eclairage (CIE) L*a*b* system at three times: 24 hours after immersing in artificial salvia (baseline), 24 hours after fluoride varnishes application and after brushing. The amount of color changes was calculated for all of the specimens as follows: ΔE1 (difference between fluoride application-base line), ΔE2 (difference between brushingfluoride application), and ΔE3 (difference between brushing-base line). P < 0.05 was considered as significant. Statistical analysis was performed by one-way ANOVA and post-hoc Tukey. RESULTS: The maximum and minimum color changes after applying varnishes were observed by Nupro and Profluoride, respectively. A significant difference was observed between ΔE 1 values of all types of studied varnishes (P < 0.01) except Durashield and Fluorilaque (P = 0.35). After brushing, no significant difference was shown between color change of stained specimens due to Durashield, Fluorilaque, and Nupro. There was no significant difference between ΔE 3 values of Durashield and Fluorilaque. CONCLUSION: Trends of color change after using all studied varnishes were clinically acceptable (ΔE < 3.3). Durashield, Nupro, Fluorilaque, and Profluoride varnishes can be used without adversely affecting the color of flowable composite resin. KEYWORDS: Fluoride Varnish; Discoloration; Resin Composit

The experimental and numerical analysis of the ballistic performance of elastomer matrix Kevlar composites

In this paper, the behavior of high-velocity impact of Kevlar fabric and elastomer composites was investigated both experimentally and numerically. The experimental tests were performed by a gas gun device and hemispherical projectiles at different velocities, ranging from 122 m/s to 152 m/s for 2- and 4-layer samples. The penetration resistance of these composites during impact was determined using ABAQUS/Explicit. The present study's novelty lies in choosing the finite element model for Kevlar fabric and elastomer matrix in composites with nonlinear behavior to estimate the damage mechanism in the impact zone. For this purpose, the material model of the formable was used to define the damage criteria for Kevlar, and the material model of the VUMAT was used to consider the non-linear behavior and damage evolution of elastomer matrix with one of the damage criteria. Then, the dynamic behavior of the laminate was studied by a Split Hopkinson Pressure Bar. The effect of the number of layers, the shape of the projectile, the energy absorption and failure mechanisms were studied. The verification of this numerical model with experimental observations showed good agreement. The results reveal that elastomeric composites can cause to increase energy absorption and reduce the damaged area

A comparative study on hypoglycemic properties, lipid profile and bioactive components of hydro-alcoholic extracts of cooked and raw Brassica napus.

Introduction: Many plants with anti-oxidant properties proved to be effective on diabetes treatment. Brassica napus (turnip) is an anti-oxidant plant consumed raw or cooked. In this study, we examined and compared hypoglycemic and hypolipidemic properties of raw and cooked Brassica napus in diabetic rats. Objectives: Due to measuring bioactive component of Brassica napus as a rich source of flavonoid we investigate the hypoglycemic properties in raw and cooked type. Material and Methods: For this experimental study, 50 male Wistar rats weighing 200-250 g were designated into five groups of 10 consist of control, diabetic control, diabetic cooked turnip, diabetic raw turnip, and diabetic glibenclamide. The alloxan-induced diabetic rats received extracts orally for 4 weeks. Then, the serum biochemical factors were measured and compared statisticaly by analysis of variance (ANOVA) test. Results: Serum glucose, triglyceride (TG), cholesterol, and low density lipoprotein cholesterol (LDL-C) were significantly decreased in cooked and raw turnip rats compared to control ones. Cooked and raw Brassica napus extracts both helped high density lipoprotein cholesterol (HDL-C) increase; cooked turnip competency was superior in view of cholesterol and LDL-C decrease as well as HDL-C increase (P < 0.05). The mean difference in glucose and TG decrease was not significant between diabetic cooked turnip and diabetic raw turnip rats. Conclusion: Improving the blood glucose and lipid levels diabetic rats, in this study, may indicate that both raw and cooked Brassica napus extracts (especially the cooked one) may be beneficial in diabetic patients

Effects of silver nanoparticle on lactate dehydrogenase activity and histological changes of heart tissue in male wistar rats

Background & Objective: The silver nanoparticles are important in many applications of nanoparticles on human health . The toxicity of silver nanoparticles are not well documented yet. The aim of this study was to investigate the effect of silver nanoparticles on lactate dehydrogenase activity and histological changes in heart tissue.   Materials &Methods: In this study, 40 adult male wistar rats of 220±20gr were divided in to five groups including control and four experimental groups. The latter groups were injected intraperitoneally spherical nano silver particles of 50, 100, 200 and 400 ppm respectively for five consecutive days. Then three, eight and twelve days after the last injection, blood samples were collected and lactate dehydrogenase (LDH) activity was assayed . Also, tissue samples from the heart muscle were prepared and studied after staining with Hematoxiline-Eosine. Data of LDH activity was analyzed by One way- ANOVA- test and P-value of ≤ 0.05 were considered as significant.   Results : The result showed that different concentrations of silver nanoparticles have no significant effect on the lactate dehydrogenase (p=0.192) . T he histological study of the tissue after exposure to 400 ppm concentration of silver nanoparticles showed the start of primary apoptosis in heart tissue.   Conclusion: The LDH activity was not changed significantly after exposure to different concentration of silver nanoparticles, which shows the safety of these particles on LDH activity

Evaluation of the effect of various types of fluoride varnishes on color stability of a composite resin

BACKGROUND AND AIM: Fluoride varnish as an extrinsic factor may cause discoloration in tooth-colored restorative materials. This research compared the impact of different fluoride varnishes on color change of a composite restorative material. METHODS: This laboratory experimental study was conducted on 40 specimens of flowable composite resin were divided into four groups based on the brand of applied varnishes (Durashield, Nupro, Fluorilaque, and Profluoride varnishes) (n = 10). Color measuring (ΔE) was performed using the easy shade device and according to Commission Internationale de l’Eclairage (CIE) L*a*b* system at three times: 24 hours after immersing in artificial salvia (baseline), 24 hours after fluoride varnishes application and after brushing. The amount of color changes was calculated for all of the specimens as follows: ΔE1 (difference between fluoride application-base line), ΔE2 (difference between brushing-fluoride application), and ΔE3 (difference between brushing-base line). P < 0.05 was considered as significant. Statistical analysis was performed by one-way ANOVA and post-hoc Tukey. RESULTS: The maximum and minimum color changes after applying varnishes were observed by Nupro and Profluoride, respectively. A significant difference was observed between ΔE 1 values of all types of studied varnishes (P < 0.01) except Durashield and Fluorilaque (P = 0.35). After brushing, no significant difference was shown between color change of stained specimens due to Durashield, Fluorilaque, and Nupro. There was no significant difference between ΔE 3 values of Durashield and Fluorilaque. CONCLUSION: Trends of color change after using all studied varnishes were clinically acceptable (ΔE < 3.3). Durashield, Nupro, Fluorilaque, and Profluoride varnishes can be used without adversely affecting the color of flowable composite resin