Introduction: Stainless steel crowns (SSCs) are widely used in restoring severely damaged primary molar teeth. Since these crowns do not adapt ideally to tooth substance, they may lead to some changes in surrounding gingiva. This clinical study was performed to evaluate the effect of Stainless steel crowns placed on primary molars on gingival structures. Materials & Methods: In this retrospective study, 117 crowns in eighty four 4-11 year old children attended to pediatric department of Zahedan dental school were evaluated. Convenience sampling method was done. Some clinical factors such as gingival index, tooth type, state of being either right or left molar, or upper or lower molar, time elapsed after cementation, crown marginal adaptation, excessive cementation around the margin of crown and the oral hygiene level were examined. Kruskal-Wallis and Mann-Whitney tests were used for data analysis through SPSS 15 software (P<0.05). Results: In our study only 11.1% of the evaluated crowns demonstrated clinically healthy gingiva, and there was a significant correlation between upper and lower molar, crown marginal adaptation and oral hygiene level with gingival index (P<0.05), while gingival index was not significantly affected by tooth type, tooth side, time elapsed after cementation and presence of excessive cement around the margin of crown and sex (P>0.05).Conclusion: Stainless steel crowns had no harmful effect on the gingiva provided performing standard preparation procedures especially in upper molars and stablishing proper marginal adaptation and good oral hygiene level.

Introduction: The bonding process of the brackets to enamel has been a critical issue in orthodontic research. The purpose of this study was to evaluate the shear bond strength of 3 lightcured adhesives (transbond XT, Z250, light bond).Materials & Methods: In this study sixty extracted human premolars were collected and randomly divided into 3 test groups. All teeth were etched by 37% phosphoric acid. In first group brackets were bonded by Transbond XT adhesive, in group two brackets were bonded by Light bond adhesive and in third group were bonded by filtek Z250 composite. All of them were cured with Ortholux xt for 40 seconds.24 hours after thermocycling, Shear Bond Strength (SBS) values of these brackets were recorded using a Universal Testing Machine. Adhesive Remnant Index (ARI) scores were determined after the failure of the brackets, using Stereo Microscope the data were analyzed using ANOVA and Chi-square tests.Results: Mean shear bond strength of Transbond XT, light bond and Z250 were 28.9±2.25 MPa, 25.06±1.98 MPa and 26.8±2.57 MPa, respectively. No significant difference was observed in the SBS among the groups and a clinically acceptable SBS was found for the three adhesives. ARI scores were not significantly different between the various groups (P>0.05).Conclusion: This study showed that the Z250 can be used as light bond and transbond xt to bond orthodontic brackets and ARI and SBS scores were not significantly different.

Background and Objective: Denture fracture due to excessivethickness, malocclusion or other traumas during sneezing or washingare disadvantages of acrylic prosthetics and PMMA resin. So furthermethods are needed to increase their transverse strength. Althoughthere are many studies on reinforcing and modifying withcopolymers, cross–linking or use of metallic or fibric strengtheners toenhance mechanical properties, There are limited studies withparadoxical results. The aim of this study was to compare thetransverse strength between reinforcement with polyethylene fiberand two older methods (Stainless steel, metallic mesh).Subjects and Methods: In this study 40 PMMA resin samples (65x12x3 mm) were made and categorized in 4 groups: With noreinforcing agent (control group); with metal wire (diameter 1.0mm); with metal mesh (diameter 0.3 mm) and with polyethylene fiber (Fibre–braid). These samples were put to 3-point loading test byInstron universal testing machine.Results: The average transverse strength in control group was 78.37MPa and for three other groups: metallic wire, mesh and polyethylenefibers, in sequence, were 80.25 MPa, 9 MPa and 78.56 MPa. Theresults were not statistically significant (P>0.05).Conclusion: Reinforcing the acrylic resin using different techniquesdo not produce increases in transverse strength in comparison withthe conventional acrylic resin with no reinforcement. Therefore, noneof the tested techniques are recommended.

The robustness of steel joints in fire is important for steel building structures because of the need to prevent progressive collapse. Stainless steel is widely used in building construction mainly because of its corrosion resistance, but it also possesses improved fire resistance compared with conventional non-alloy, fine grain structural steels. Extensive research performed on the robustness of steel joints in fire has revealed that failure at elevated temperature may be controlled by bolt shear for fin plate and web cleat connections. Hence, this study focussed on the use of Stainless steel in experimental tests conducted on fin plate and web cleat connections at high temperatures. In addition, this study investigated the use of a component-based model to predict connection performance at elevated temperature.

Nowadays, due to mechanical, physical, thermal, electrical, and vibration properties, metallic multilayer rods have specific applications in industry. Bimetallic rods made from layers with two different materials have been considered by manufacturers in recent years for simultaneous use of the properties of several materials in a single work piece, such as high strength, corrosion resistance, wear resistance, and improved stress distribution. In this research, the tensile test was performed on steel wire and Stainless steel pipes to obtain the stress-strain curve of each sample. Wire drawing dies have been used to make bimetallic rods. Then, two samples of the bimetallic rod were made by swaging with the reduction ratio of 9. 75% and 21%. Samples were cut by wire cut machine after production. For interlayer strength testing, dies were designed based on the punch method. The test results were used to calibrate the parameters of the adhesive element in the software. The simulation was performed, using Ansys 17. 0 software. Then the results were compared with experimental results. The effects of reduction ratio, internal diameter, sample length, and clad thickness were investigated. The experimental results were in good agreement with the simulation results. By increasing the reduction ratio, the force required for the separation of the two layers has increased, resulting in increased bonding strength between layers.

Dissimilar welding of AISI 304L austenitic Stainless steel to AISI 409 ferritic Stainless steel with GMAW process usingtwo Ar-O2 and Ar-CO2 shielding gas mixtures was studied. ER316LSi and ER309LMo filler metals were chosen by considering 5 and 15% delta ferrite according to the Schaeffler equations and diagram. Based on the observations, both filler metals accompanied by Ar-2%O2 shielding gas resulted in acceptable weldments. Yield strength and UTS of tensile samples were 288 and 424 MPa, respectively. All tensile samples fractured in the ferritic base metal. Microhardness test results demonstrated that the maximum hardness of 190-200 HV was obtained from ER316LSi weld metal. The minimum hardness of 145 HV was found in the HAZ of 409 side mainly due to the grain coarsening. Microstructural examinations revealed needle-like precipitates formed perpendicular to each other in the HAZ of 409 Stainless steel. It seemed that the pre-existing TiC precipitates evolved into the needle shape precipitates as a result of rapid heating and cooling rates during the welding process.

In this paper microstructure, phase formation and Vickers hardness profile of the hardfaced layer, Co-based alloys (Stellite-6) filler metal on 410 martensitic Stainless steel specimens with 309 austenitic Stainless steel interlayer were investigated. Gas Tungsten Arc Welding (GTAW) cladding was carried out for deposition. The specimens were investigated by an X-ray diffractometer, energy dispersion spectroscopy (EDS), scanning electron microscopy (SEM) and hardness test. According to the analyzed results, the microstructure of the clad layer consists of eutectic structure, and undissolved carbides dispersed in the matrix of the Co-based alloy with dendritic structure. The dendrites have epitaxial growth. Diffusion of carbon from the liquid Stellite to the austenitic Stainless steel took place along grain boundaries resulting in the formation of chromium carbide “arms” that penetrated along the austenite grain boundaries in the interfacial region. The dilution of the clad layer by Fe from the substrate decreases hardness, wear and corrosion resistance. The interlayer resulted in a decrease in the dilution of Fe and increase in hardness.