Fabrication, characterization, and optimization selection of ceramic particulate reinforced dental restorative composite materials

The objective of the article is to explore the fabrication of dental restorative composite materials and the ranking order using the preference selection index (PSI) as a multi criteria decision making (MCDM) technique under a set of conflict performance defining criteria (PDCs). The polymer matrix of the dental restorative composite was prepared using bisphenol a-glycidyl methacrylate (55 wt.%), triethylene glycol dimethacrylate (44 wt.%), camphorquinone (0.3 wt.%), and ethyl 4-(dimethylamino) benzoate (0.7 wt.%). Five different dental restorative composite material compositions were fabricated using hybrid nSiO2-TiO2 particulates with a variation of nSiO2 (0, 2, 4, 6, 8 wt.%) while TiO2 is constant (15 wt.%). The results revealed that an increasing trend has been found in compressive strength, flexural strength, Vickers hardness, etc., while a decreasing trend has been shown in depth of cure, polymerization shrinkage, degree of conversion etc. The performance analysis of five dental composite formulations via the PSI method shows the following ranking order: nS4 > nS6 > nS2 > nS0 > nS8. The obtained experimental results are associated with the ranking order of the different sets of dental composite formulations. Hence, the preference selection index approach is one of the best techniques among MCDM techniques for ranking under different PDCs.

Statistical Analyses of the Strengths of Particulate Reinforced Metal Matrix Composites (PRMMCs) Subjected to Multiple Tensile and Shear Stresses

For design and application of particulate reinforced metal matrix composites (PRMMCs), it is essential to predict the material strengths and understand how do they relate to constituents and microstructural features. To this end, a computational approach consists of the direct methods, homogenization, and statistical analyses is introduced in our previous studies. Since failure of PRMMC materials are often caused by time-varied combinations of tensile and shear stresses, the established approach is extended in the present work to take into account of these situations. In this paper, ultimate strengths and endurance limits of an exemplary PRMMC material, WC-Co, are predicted under three independently varied tensile and shear stresses. In order to cover the entire load space with least amount of weight factors, a new method for generating optimally distributed weight factors in an n dimensional space is formulated. Employing weight factors determined by this algorithm, direct method calculations were performed on many statistically equivalent representative volume elements (SERVE) samples. Through analyzing statistical characteristics associated with results the study suggests a simplified approach to estimate the material strength under superposed stresses without solving the difficult high dimensional shakedown problem.