The interim restorations play an important role in protection of hard and soft oral tissue and providing the critical function and esthetics before the final restoration replacing. Temporary restorations must have sufficient flexural strength to resist deformation during mastication force. Moreover, sufficient surface hardness is also necessary to resist abrasion. The color stability of materials is considered as an important clinical criterion, specifically in esthetics zone. Several materials have been applied to improve ‏the flexural strength and surface hardness for representing clinical success. Zirconia nanoparticles show desirable features, such as high hardness, biocompatibility, and favorable color because of its white color. ‏It seems that the addition of the nano zirconia to acrylic resins can be the appropriate method for improving interim restoration.

This paper presents a methodology to systematically quantify the interphase thickness in epoxy nanocomposites using local mass density profile.

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Various nano- and micro-sized fillers can be integrated into polymers to enhance their flame-retardant performance. In this work, a diglycidyl-ether bisphenol A epoxy was used as the matrix and nanostructured silica aerogel (AG) and ammonium polyphosphate (APP) microparticles were investigated as fillers to improve the flame-retardant and thermal properties of the epoxy. The anti-flame, thermal, and mechanical properties of the composites were investigated for different volume fractions of filler particles. It was found that APP decreased the burning rate while significantly improving the thermal stability. To investigate the flame resistant properties of combined AG and APP, an optimized ratio of AG and APP was added to the epoxy, leading to a stable flame-retardant epoxy with a low thermal conductivity and improved glass transition temperature (Tg). The synergy between the AG and APP in composite samples resulted in an interesting burning behavior where sample core was relatively less deteriorated compared with the samples containing only APP or AG. This was attributed to the decrease of thermal conductivity due to the addition of AG. Lastly, samples containing APP showed the highest limiting oxygen index percentage and it was found that only small amounts of APP are required to make the epoxy flame-retardant.