Dimer acid based metacrylates and TCD-urethane are promoted as new monomers of nano-hybrid resin based composites as alternatives for the conventional BisGMA. Investigations of this study focused on the mechanical and the storage behavior of nano-hybrid resin based composites (RBCs) composed of these new types of monomers in comparison to RBCs using BisGMA.

 Flexural strength and modulus were determined in a three-point-bending test. Additionally, the modulus of elasticity was measured on microscopic scale (E _micro ) using an automatic microhardness indenter. Tests were performed on samples after 24h storage in distilled water, as well as after thermocycling and storing the materials for four weeks in either distilled water, artificial saliva or ethanol.

 The six measured materials showed a pronounced decrease of flexural strength, flexural modulus and E _micro after four weeks storage in alcohol. Results after four weeks storage in water and saliva could not be proven to be significantly different. The most sensitive factor of influence on all test parameters was the material.

 Nano-hybrid composites with new or conventional monomers performed similar in regard to the mechanical properties and the behavior of the materials after aging.

  Source: Dental Materials

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