The Effect of in Vitro Sample Preparation Methods on Bond Strength of Mineral Trioxide Aggregate to Root Dentin

Introduction: The aim of this study was to compare the effect of sample preparation methods on push-out bond strength of mineral trioxide aggregate (MTA). Methods and Materials: Twenty-four extracted human mandibular premolars with single root canal were selected for this in vitro study. After instrumentation, irrigation and drying of root canals, they were randomly divided into two experimental groups (n=12). Group 1: After removing the 3 mm of root ends, 2 mm thick sections were established from the remaining roots. MTA was mixed following the manufacturers’ recommendations and root sections were filled. Group 2: The whole root canal was used for filling and packing of MTA and like group 1, after removing the 3 mm of root ends, root sections were provided. Push-out bond strength was measured and analyzed by the independent t-test. Level of statistical significance was set at 0.05. Results: The highest mean push-out bond strength was in apical section of group 2 (4.86±1.31) and the lowest value was in coronal section of group 2 (3.05±1.15). The results of the independent t-test showed a significant difference between two groups only in the apical section (P=0.02). Conclusion: Based on the results of this in vitro study, the highest mean push-out bond strength was in apical section of group 2. It seems that using the whole root canal for MTA application is better for MTA in vitro analysis of bond strength to root dentin because it is more similar to the clinical conditions.Keywords: Bond Strength; Endodontics; Mineral Trioxide Aggregate; Root Denti

Antibacterial Effect of Two Nano Zinc Oxide Gel Preparations Compared to Calcium Hydroxide and Chlorhexidine Mixture

Introduction: The aim of this study was to compare the antibacterial effects of two gels containing zinc oxide and zinc oxide/silver nanoparticles and a mixture of calcium hydroxide and 0.12% chlorhexidine as intracanal medicaments in root canals contaminated with Enterococcus faecalis (E. faecalis) at different time intervals. Methods and Materials: After preparation and culturing of E. faecalis in 132 single root teeth, the initial count of bacteria was performed. Then, different materials as intracanal medicaments were used in periods of 3, 7 and 14 days (group 1: calcium hydroxide with 0.12% CHX paste; group 2 zinc oxide nanoparticles gel; group 3: zinc oxide/silver nanoparticles gel; group 4: normal saline as the control group). After the specified time, intracanal medicament was removed and the final count of bacteria was performed. Antibacterial effect of materials was counted by measuring the percentage reduction in the colony counts (RCC). Data were analyzed using the descriptive statistics (Mean±SD) and multi-factorial analysis of variance (by taking into account the effect of the time factor on the dependent variable). Results: There were no statistically significant differences among mean RCC of different time intervals in each group (P=0.09). However, the differences in mean RCC of different dressing materials were significant (P<0.001). The effect of interaction between time and materials was significant (P=0.015). Comparison of the antibacterial effects of experimental agents at different time intervals showed that the mean RCC in group 1 was higher than other groups (P<0.001). The difference in antibacterial effect between groups 2 and 3 was not significant (P>0.05). The minimum antibacterial effect was observed in group 4 (P<0.0001). Conclusions: The mixture of calcium hydroxide/chlorhexidine as an intracanal medicament was more effective than zinc oxide and zinc oxide/silver nanoparticles gels. Keywords: Calcium Hydroxide; Chlorhexidine; E. faecalis; Nanoparticles; Zinc Oxid

Experimental analysis and mathematical prediction of Cd(II) removal by biosorption using support vector machines and genetic algorithms

We investigated the bioremoval of Cd(II) in batch mode, using dead and living biomass of Trichoderma viride. Kinetic studies revealed three distinct stages of the biosorption process. The pseudo-second order model and the Langmuir model described well the kinetics and equilibrium of the biosorption process, with a determination coefficient, R2 > 0.99. The value of the mean free energy of adsorption, E, is less than 16 kJ/mol at 25°C, suggesting that, at low temperature, the dominant process involved in Cd(II) biosorption by dead T. viride is the chemical ion-exchange. With the temperature increasing to 4050°C, E values are above 16 kJ/mol, showing that the particle diffusion mechanism could play an important role in Cd(II) biosorption. The studies on T. viride growth in Cd(II) solutions and its bioaccumulation performance showed that the living biomass was able to bioaccumulate 100% Cd(II) from a 50 mg/L solution at pH 6.0. The influence of pH, biomass dosage, metal concentration, contact time and temperature on the bioremoval efficiency was evaluated to further assess the biosorption capability of the dead biosorbent. These complex influences were correlated by means of a modeling procedure consisting in data driven approach in which the principles of artificial intelligence were applied with the help of support vector machines (SVM), combined with genetic algorithms (GA). According to our data, the optimal working conditions for the removal of 98.91% Cd(II) by T. viride were found for an aqueous solution containing 26.11 mg/L Cd(II) as follows: pH 6.0, contact time of 3833 min, 8 g/L biosorbent, temperature 46.5°C. The complete characterization of bioremoval parameters indicates that T. viride is an excellent material to treat wastewater containing low concentrations of metal

Design and Implementation of a Web-based Greenhouse Remote Monitoring System with Zigbee Protocol and GSM Network

In modern and big greenhouses, it is necessary to measure several climate parameters to automate and control the greenhouse properly. Monitoring and transmitting by cable may lead to an expensive and stiff measurement system. Since, Wireless Sensor Network (WSN) is a distributed system that consists of small-size wireless sensor nodes equipped with radio and one or several sensors; it is a low cost option to build the required monitoring system. In this paper, we introduce and implement an intelligent monitoring system based on WSN by using Xbee modules. The Xbee Series 2 hardware uses a microchip from Ember Networks that enables several different flavors of standards-based ZigBee mesh networking. All gathered information by sensors, are sent to a remote center in form of GPRS packets through a GSM network and viewed by monitoring software. The proposed system has low power consumption, low cost and simple driver circuits. Furthermore, it can support various types of digital and analog sensors

Exploring the state of tourism in Iran’s higher education

In tourism, like any other service industry, the people offering service are a constituent part of the product, and their expertise, theoretical knowledge, and job skills undeniably affect the quality of services. Hence, Composition and implementation of human resource development strategies is of a great importance and education/training, therein, plays a major part. Higher education, compared to other educational levels, is of greater significance for being in charge of training expert human resources to create knowledge and transfer it to the lower levels. Among the component indices of higher education system, the scientific criteria, including learning factors, teaching factors, and learning conditions and facilities, correlate directly with the quality of academic courses. In order to explore the state of these criteria in tourism academic courses, two models are used: horizontal model (based on the scientific nature of courses) and vertical model (based on the education level and hierarchy). Having investigated the indices of scientific system of tourism education based on these two models, it allows ascertaining the efficiency of education system in terms of form and content. This research focuses on identification of the model and quality of scientific and learning criteria of tourism in Iran’s higher education, utilizing a comparative-longitudinal research method. A comparative study was also performed between Iran and Turkey, using interviews and secondary data analysis. Results indicate that although the number of students and tourism education centers has increased dramatically in Iran, the development model has not conformed to the selected horizontal and vertical models of the research in terms of form and content. In addition, serious shortcomings seem to exist in learning facilities and conditions of all educational courses

Exploring the state of tourism in Iran’s higher

In tourism, like any other service industry, the people offering service are a constituent part of the product, and their expertise, theoretical knowledge, and job skills undeniably affect the quality of services. Hence, Composition and implementation of human resource development strategies is of a great importance and education/training, therein, plays a major part. Higher education, compared to other educational levels, is of greater significance for being in charge of training expert human resources to create knowledge and transfer it to the lower levels. Among the component indices of higher education system, the scientific criteria, including learning factors, teaching factors, and learning conditions and facilities, correlate directly with the quality of academic courses. In order to explore the state of these criteria in tourism academic courses, two models are used: horizontal model (based on the scientific nature of courses) and vertical model (based on the education level and hierarchy). Having investigated the indices of scientific system of tourism education based on these two models, it allows ascertaining the efficiency of education system in terms of form and content. This research focuses on identification of the model and quality of scientific and learning criteria of tourism in Iran’s higher education, utilizing a comparative-longitudinal research method. A comparative study was also performed between Iran and Turkey, using interviews and secondary data analysis. Results indicate that although the number of students and tourism education centers has increased dramatically in Iran, the development model has not conformed to the selected horizontal and vertical models of the research in terms of form and content. In addition, serious shortcomings seem to exist in learning facilities and conditions of all educational courses

Gelatin–Curcumin Nanocomposites as a Coating for Implant Healing Abutment: In Vitro Stability Investigation

Regarding the importance of preventing peri-implantitis in dental implants, the current study aimed to coat a healing abutment with gelatin–curcumin nanocomposites, and the stability of this coating on the healing abutment was evaluated. A cell viability measuring test was used to determine the cytotoxicity of nanocomposites against dental pulp stem cells. To show the pattern of curcumin release from nanocomposites, drug dissolution apparatus two was applied. Then, 16 healing abutments were examined in vitro. Titanium healing abutments were coated with the gelatin–curcumin nanocomposite. The dip coating method was applied for coating and the consistency of coated cases was evaluated at intervals of one, 30, and 60 days after coating inside the simulated body fluid (SBF) solution. A scanning electron microscope (SEM) was used for investigating the microstructure and morphology of coatings, and an energy dispersive X-ray (EDX) was applied for determining the combination of the coating. Moreover, the healings were weighed before and after coating via an accurate digital scale with an accuracy of 0.0001. Finally, the data were analyzed using SPSS software. The prepared nanocomposite was non-cytotoxic against tested cells. The nanocomposite showed a relatively rapid release pattern in the first 10 days for curcumin. The release of curcumin from the nanoparticles continued slowly until the 30th day. The weight changes were statistically significant (p-value < 0.001) during this time. Based on the post hoc test, the weight between two times immediately after coating and 30 days after coating, and also one day after coating and 30 days after coating, was statistically insignificant. The results revealed that the coating of the gelatin–curcumin nanocomposite on the healing was successful and this consistency was kept for at least one month. It is necessary to investigate more evaluations in different fields of physicochemical, mechanical, and antimicrobial aspects for coated healing abutments

Gelatin–Curcumin Nanocomposites as a Coating for Implant Healing Abutment: In Vitro Stability Investigation

Regarding the importance of preventing peri-implantitis in dental implants, the current study aimed to coat a healing abutment with gelatin–curcumin nanocomposites, and the stability of this coating on the healing abutment was evaluated. A cell viability measuring test was used to determine the cytotoxicity of nanocomposites against dental pulp stem cells. To show the pattern of curcumin release from nanocomposites, drug dissolution apparatus two was applied. Then, 16 healing abutments were examined in vitro. Titanium healing abutments were coated with the gelatin–curcumin nanocomposite. The dip coating method was applied for coating and the consistency of coated cases was evaluated at intervals of one, 30, and 60 days after coating inside the simulated body fluid (SBF) solution. A scanning electron microscope (SEM) was used for investigating the microstructure and morphology of coatings, and an energy dispersive X-ray (EDX) was applied for determining the combination of the coating. Moreover, the healings were weighed before and after coating via an accurate digital scale with an accuracy of 0.0001. Finally, the data were analyzed using SPSS software. The prepared nanocomposite was non-cytotoxic against tested cells. The nanocomposite showed a relatively rapid release pattern in the first 10 days for curcumin. The release of curcumin from the nanoparticles continued slowly until the 30th day. The weight changes were statistically significant (p-value < 0.001) during this time. Based on the post hoc test, the weight between two times immediately after coating and 30 days after coating, and also one day after coating and 30 days after coating, was statistically insignificant. The results revealed that the coating of the gelatin–curcumin nanocomposite on the healing was successful and this consistency was kept for at least one month. It is necessary to investigate more evaluations in different fields of physicochemical, mechanical, and antimicrobial aspects for coated healing abutments