The objective of the present work is the evaluation of the contents of inorganic particles in the mechanical and tribological behavior of polymeric matrix composites. In order to control easily the production of the specimens, a polyester resin was used as matrix and silica particles were added as inorganic filler. The volumetric particle content was ranged from 0 to 46%. In order to understand the influence of the inorganic load was evaluated the mechanical and tribological behaviors for several percentage of particle content was evaluated. There are several applications of inorganic fillers where their volume percentage is important, namely in dentistry. In posterior restorative resin materials, the particles percentage in volume goes up to 50 or more. In most cases spherical and irregular shaped fillers are dispersed randomly. In the studied composites the filler has irregular shape therefore the connection between the matrix and the particles is more effective. Function of the shape, concentration degree and particle size of the filler the composite mechanical properties vary greatly. All of these factors influence the mechanical properties of the particle-reinforced composite, namely: wear resistance, hardness, flexural modulus, flexure strength and toughness The morphology of the failure surfaces was observed by scanning electron microscopy and the results were widely discussed.