NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980’s NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not costeffective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight...

Bismaleimide (BMI) resins are developed very rapidly due to the demands of the defense and aerospace industries. They are cross-linked polymers which process like epoxy resins but have an upper use temperature of 230°C, compared to the epoxy upper use temperature of 175°C. Also due to the available intrinsic properties of BMI resins such as higher thermal stability and lower toxicity than those...

statement of the problem addition of metallic nano-particles to composite resins can change their water contact angle purpose the aim of this study was to evaluate the effect of addition of nano-particles of silver and zinc oxide to composite resins on their water contact angle materials and methods this in vitro study was performed on 60 composite resin samples. nano-silver and nano-zinc oxide...

Background. Acrylic resins used in restorative dentistry are the most popular denture base material, because they have good optical properties and small solubility in body fluids. However their mechanical properties are limited and therefore acrylic resins require different methods of reinforcement one of which can be application of different kinds of fibers. Objectives. To investigate the effe...

background: the purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (esthet•x hd, clearfi l ap-x, gradia direct) and fi ve nanohybrid composite resins (ceram•x, gc kalore, g-aenial, grandio, grandioso), after staining and bleaching procedures. materials and methods: the composite resins were polymerized with a curing light (celalux ii, voco...

tooth fracture is a common dental problem. by extension of cavity dimensions, the remaining tooth structure weakens and occlusal forces may cause tooth fracture. the aim of this study was to evaluate and compare the fracture resistance of teeth restored with direct and indirect composite restorations.sixty-five sound maxillary premolar teeth were chosen and randomly divided into five groups eac...

objectives: this study sought to compare the push-out bond strength of two bulk-fill and one conventional composite to intracanal dentin in primary anterior teeth. materials and methods: this in vitro, experimental study was conducted on 39 primary anterior teeth, which were randomly divided into three groups. after cleaning and shaping, the root canals were filled with metapex in such a way th...

In this study, acrylated soybean oil (AESO) was used as modifying agent for DGEBF-type epoxy resin (ER). AESO was used as a co-matrix in 50 wt % with ER. Composites with ecofriendly natural fillers-banana bark and seashell were prepared. MNA was used as a hardener. Effect of banana peel (BP) and seashell (SSh) fillers on mechanical properties, such as tensile strength, elongation at break, and ...

introdouction: bleaching has become a common treatment for improving the appearance of natural teeth. however, the need to protect dental restorations from bleaching agent exposure is inevitable, as these agents may change the color of restorative materials by oxidation. filtek p90 composite resin has recently been introduced with the aim of decreasing polymerization shrinkage. the purpose of t...