The applicability of organomodified nanoclays as new fillers for mechanical reinforcement of dental composites

Objectives This study reports the evaluation of changes in crosslink structure and mechanical properties of dental microhybrid composite reinforced with clays when compared to silica nanofillers, which are already extensively used for this application. Materials and methods A standardized resin matrix with a glycerolate dimethacrylate, triethylene glycol dimethacrylate, and urethane dimethacrylate copolymers associated with a camphorquinone photoinitiator system was blended with 75wt% filler content. As fillers, two organically modified clays (hydrophilic silica and organomodified silica) and a boron-aluminum-silicate glass with 4 mu m were used to obtain nanohybrid nanocomposites. The samples were prepared by light curing and were evaluated by measuring flexural strength, elasticity modulus, hardness, tensile resistance, and crosslinking. Results The mechanical test results indicated that the system with 2.5% clay was better dispersed in the system, while the highest concentrations caused agglomeration of these clays. On the other hand, the silicas showed gradual gain in properties. The increase in concentration of all nanofillers reduced the crosslinking ability of the systems. This behavior can be explained because the clay's presence makes the reaction medium more viscous or because the fillers act as points of light absorption and scattering.