Evaluation of Shear Bond Strength of Four Commercially Available Resin Cements: In Vitro Study

INTRODUCTION: Dentists have searched for ideal restorative material for many years, although direct restorative materials such as amalgam, cements and composites have been used with reasonable good success during past several decades, but they are not ideal for large restorations or for fixed partial dentures. When a restoration is placed in aesthetic zone, the surface quality and aesthetic potential over a period of time becomes very crucial to provide a life like restoration to the patients. The end of twentieth century saw vast development in all-ceramic dental restorations because of increased popularity of all-ceramic materials. Dental ceramics are attractive dental restorations, because of their biocompatibility, long term color stability, wear-resistance, and their ability to be formed into desired shapes. Dental restorations using all-ceramic materials in association with adhesive cements have become popular in the last decade, primarily because of esthetic properties such as translucence, fluorescence, and opalescence that better simulate the appearance of natural dentition. The cementation process is vital for the clinical success of all-ceramic restorations. It has been purported that some all-ceramic restorations may be cemented with zinc phosphate, glass ionomer, or resin composite cements. Therefore, the success of the cementation process may depend on the composition of the ceramic material. When zinc phosphate or glass- ionomer cements are used, adequate retention form of the preparation is necessary. When this is compromised, adhesive luting systems are recommended. The bond of the resin luting agent to the tooth structure is enhanced by acid etching the tooth structure and by the use of a dental adhesive. The applications of dual-polymerizing resin cements for all-ceramic restorations have considerably increased due to the ability of these cements to polymerize completely and their greater resistance to occlusal loading. Since the use of all ceramic restorations requires considerable support from the underlying composite resin cement and dentin for a successful clinical outcome, the luting agent should have high bond strength, not only to the ceramic surface, but also to the tooth surface. The long-term success of resin bonded all-ceramic restorations depends in part on a durable bond being created between the hard tissues of the tooth and the adhesive cement4. A durable bond between the adhesive cement and the restoration is also critical, throughout the lifetime of a restoration. There is agreement that a stable bond increases both the retention and the fracture resistance of the abutment and the restoration and that it reduces the incidence of micro leakage. AIM AND OBJECTIVES: The aim of this study was to compare the shear bond strength of four commercially available resin cements with their respective bonding system to human teeth. The objectives of this in vitro study are: 1. To compare the shear bond strength of four commercially available resin cements with their respective bonding system to human teeth. 2. To conduct failure mode analysis of resin cements using microscopy. METHODOLOGY: I. Tooth Preparation, II. Laminate Fabrication, III. Cementation of Veneers to the tooth, IV. Experimental design- Randomized four groups of twelve teeth comprising Six Anterior and Six Posterior teeth. a. Group I Rely X. b. Group II Variolink N. c. Group III Calibra. d. Group IV SeT PP. V. Measurement of Shear Bond Strength by Universal Testing Machine (UTM). VI. Statistical Evaluation. STATISTICAL EVALUATION: Statistical analysis of the Maximum load recorded was done with the use of a Software (SPSS Software). Mean of all the cement group were analyzed using One way ANOVA test with maximum load as the dependent variable and the type of Resin cements as independent variable. Unpaired T-Test was also done with <0.05 to indicate significance. SUMMARY AND CONCLUSION: This study was done to Compare and Evaluate the Shear bond strength of four commercially available resins cements namely Rely X, Variolink N, Calibra and SeT PP to human dental hard tissue and ceramic. The number of teeth sample for each group was six in number (three anterior and three posterior teeth). Ceramic Laminates was fabricated and luted to the respective human teeth samples according to manufactures instructions. The samples were stored for 24hrs in distilled water followed by thermo cycling. The sample was tested for maximum load failure using Universal Testing Machine. The data obtained was analyzed statistically by One Way ANOVA and Unpaired T-test. For Anterior teeth sample Calibra shows the highest mean load value of 464.33 and SeT PP shows the lowest value of 288.00. For Posterior teeth sample, Rely X shows the highest value of 272.97 while SeT PP shows the lowest load value of 154.33. Among all the cements SeT PP shows the lowest load values. One Way ANOVA Test for teeth sample shows insignificance of load value among all the cements at 5% of confidence level (p<0.05). Within the limitation of this study following conclusions was made: (1) There is no significance differences exist in long-term durability to human dentin between the cementing agents with their respective bonding system. (2) Simplifying the application procedures of the corresponding adhesives following three step total-etch, two step total-etch, one-step self-etch, or no use of adhesives, affect the effectiveness of the bond to human dentin

(E)-4-[(3,5-Dimethyl­phen­yl)imino­meth­yl]-2-meth­oxy-3-nitro­phenol

The mol­ecule of the title compound, C16H16N2O4, exists in the E configuration with respect to the central C=N double bond. The dihedral angle between the two benzene rings is 2.17 (9) Å. In the crystal, mol­ecules are linked via O—H⋯N hydrogen bonds into chains that propagate along the b-axis direction. There is also π–π stacking of inversion-related mol­ecules, with inter­planar spacings of 3.479 (5) Å and ring centroid–centroid distances of 3.876 (4) Å

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Vanillin Schiff bases: Molecular interactions in methanol and THF solutions

Density, ultrasonic velocity and viscosity of some vanillin Schiff bases derivativeshave been studied in methanol and tetrahydrofuran (THF) at 308.15 K. From theexperimental data, various acoustical parameters such as isentropic compressibility(κs), Rao’s molar sound function (Rm), Van der Waals constant (b), relaxation strength(r), intermolecular free length (Lf), apparent molar compressibility, etc. have beenevaluated, which helps in understanding the molecular interactions occurring inthese solutionsEn este trabajo se estudiaron la densidad, la velocidad ultrasónica y la viscosidad desoluciones de algunas bases de Schiff derivadas de la vainillina en metanol y tetrahidrofurano(THF) a 308,15 K. A partir de los datos experimentales, se evaluarondiversos parámetros acústicos, como la compresibilidad isentrópica (κs), la funciónacústica molar de Rao (Rm), la constante de Van der Waals (b), la fuerza de relajación(r), la longitud intermolecular libre (Lf), la compresibilidad molar aparente,etc., todo lo cual ayuda a comprender las interacciones moleculares que ocurren enestas soluciones

Coupled Fluid-Structure Transient Thermal Analysis of a Gas Turbine Internal Air System With Multiple Cavities

This paper presents the transient aerothermal analysis of a gas turbine internal air system through an engine flight cycle featuring multiple fluid cavities that surround a HP turbine disk and the adjacent structures. Strongly coupled fluid-structure thermal interaction problems require significant computational effort to resolve nonlinearities on the interface for each time step. Simulation times may grow impractical if multiple fluid domains are included in the analysis. A new strategy is employed to decrease the cost of coupled aerothermal analysis. Significantly lower fluid domain solver invocation counts are demonstrated as opposed to the traditional coupling approach formulated on the estimates of heat transfer coefficient. Numerical results are presented using 2D finite element conduction model combined with 2D flow calculation in five separate cavities interconnected through the inlet and outlet boundaries. The coupled solutions are discussed and validated against a nominal stand-alone model. Relative performance of both coupling techniques is evaluated

Examining the Influence of Training and Job Involvement on Employee Job Performance at Ahmedabad Janmarg Limited

This research delves into the intricate relationship between training initiatives, job involvement, and employee job performance within the operational landscape of the Bus Rapid Transit System (BRTS) in Ahmedabad. The study employs use of quantitative surveys to explore the multifaceted dynamics at play. By focusing on the specific context of BRTS, this research tried to explore the impact of tailored training programs on employee engagement and subsequently on their job performance. The correlation analysis revealed strong positive associations between Training and Job Performance, as well as between Job Involvement and Job Performance. Regression analyses reinforced these findings, indicating that the models accounted for a substantial portion of the variability in Job Performance on account of Training provided to the employees and very high portion of the variability for Job Involvement of the employees. The study's outcomes highlight the significance of effective training programs and the cultivation of job involvement in optimizing employee job performance at Ahmedabad Janmarg Limited. Strategic initiatives aimed at enhancing these factors may prove instrumental in fostering a more productive workforce. It is important to note that while these findings offer valuable insights future research could delve into additional variables to provide a more comprehensive understanding of the other factors influencing employee job performance

Coupled FE-CFD Thermal Analysis for a Cooled Turbine DisK

This paper presents transient aero-thermal analysis for a gas turbine disk and the surrounding air flows through a transient slam acceleration/deceleration “square cycle” engine test, and compares predictions with engine measurements. The transient solid-fluid interaction calculations were performed with an innovative coupled finite element (FE) and computational fluid dynamics (CFD) approach. The computer model includes an aero-engine high pressure turbine (HPT) disk, adjacent structure, and the surrounding internal air system cavities. The model was validated through comparison with the engine temperature measurements and is also compared with industry standard standalone FE modelling. Numerical calculations using a 2D FE model with axisymmetric and 3D CFD solutions are presented and compared. Strong coupling between CFD solutions for different air system cavities and the FE solid model led to some numerical difficulties. These were addressed through improvement to the coupling algorithm. Overall performance of the coupled approach is very encouraging giving temperature predictions as good as a traditional model that had been calibrated against engine measurements

Coupled Fluid-Structure Transient Thermal Analysis of a Gas Turbine Internal Air System With Multiple Cavities

This paper presents the transient aero-thermal analysis of a gas turbine internal air system through an engine flight cycle featuring multiple fluid cavities that surround a HP turbine disk and the adjacent structures. Strongly coupled fluid-structure thermal interaction problems require significant computational effort to resolve nonlinearities on the interface for each time step. Simulation times may grow impractical if multiple fluid domains are included in the analysis. A new strategy is employed to decrease the cost of coupled aero-thermal analysis. Significantly lower fluid domain solver invocation counts are demonstrated as opposed to the traditional coupling approach formulated on the estimates of heat transfer coefficient. Numerical results are presented using 2D FE conduction model combined with 2D flow calculation in five separate cavities interconnected through the inlet and outlet boundaries. The coupled solutions are discussed and validated against a nominal stand-alone model. Relative performance of both coupling techniques is evaluated

A comparative study of cascade vanes and drilled nozzle designs for pre-swirl

Design of pre-swirl systems is important for the secondary air cooling system of gas turbine engines. In this paper, three pre-swirl nozzles, a cascade vane and two drilled nozzles are analysed and their performances are compared. The two drilled nozzles considered are a straight drilled nozzle and an aerodynamically designed nozzle. CFD analyses are presented for stand-alone and pre-swirl system 3D sector models at engine operating conditions near to engine maximum power condition rotational Reynolds number (Re ?) up to 4.6 ! 10 . Nozzle performance is characterised by the nozzle discharge coefficient (C ), nozzle velocity coefficient (?η) and cooling air delivery temperature. Two commonly used eddy viscosity models are employed for the study, the standard κ-ε and Spalart-Allmaras models with wall functions. Both models give very similar results for C and η and are in reasonable agreement with available experimental data. Effects of nozzle or vane number and sealing flow have been analysed. The cascade vanes perform slightly better than the aerodynamically designed drilled nozzles but the final design choice will depend on other component and manufacturing costs. An elementary model is presented to separate temperature losses due to the nozzle, stator drag and sealing flow. Copyright © 2011 by Rolls-Royce plc