Effects of Fillers on Fiber Reinforced Acrylic Denture Base Resins

Abstract

Objectives. This study was designed to evaluate the mechanical properties of acrylic resin reinforced by the addition of four types of filler (clay, glass powder, SiO2 and ZrO2). Methods. The mixtures of filler containing resin and fiber were cured at 70oC in a water bath for 15 hours, then at 90°C for 1 hour, in 70×25×15 mm3 stone molds enclosed in dental flasks. The cured resin blocks were cut into 63.5×12.75×10 mm3 and 65×2.5×10 mm3 segments and tested for impact strength and bending strength according to ASTM specification No. 256 and ISO specification No. 1567, respectively. Specimens used in the impact strength test were reused for the Knoop hardness test. Result& The results showed that a small volume of filler increased the impact strength and had no influence on bending strength; however a large volume of filler (greater than 4%) decreased bending strength markedly. The Knoop hardness test revealed that the higher the content of filler, the greater the surface hardness. In general, of the four types of filler, SiO2 gave the best results at a ratio of 2% (w/w), based on three evaluations of the resultant mechanical properties. Conclusions. We conclude that 2% (w/w) SiO2 filler is the optimum formula of fiber reinforced acrylic resin which improves strength.