THE EFFECTS OF RESIN MATRIX COMPOSITION, FILLER VOLUME AND PARTICLE SIZE ON THE MECHANICAL PROPERTIES OF DENTAL RESIN COMPOSITES

Abstract

The behaviour of dental resin composites (DRCs) under mechanical loading has been of concern in dentistry as it determines their clinical application. The aim of this study is therefore to check the effect of the resin matrix composition, filler volume and particle size on the mechanical properties of DRCs. In this experimental in-vitro study, six types of composite resins were used as follows: Two(2) Micro hybrid- Super Cor (SC) and Natural look(NL); Two(2) hybrid- Alpha dent (AD) and Henry Schein (HS) and two(2) Nano hybrid- i-Xcite(IX) and Fusion(FS),each with varying resin matrix composition, filler volume and particle size. Samples were prepared in aluminum molds and light cured using Optilight Max GNATUS light curing unit at constant time intervals of 20 seconds as specified in literature and designed by curing light manufacturers. The specimens were stored in distilled water at 37C for 48 hours. Subsequently, the specimens were subjected to tensile test and three point loading using the BOSE Electro Force 3200 system at cross head speed of 1.0mm/min and varying speed of 0.5, 2.0 and 5.0mm/min. Henry Schein 20/20 (hybrid;bis-GMA;56%) exhibited flexural strength of 17MPa but tensile strength of 29.7MPa amongst the group. i-Xcite (nanohybrid; bis-GMA,TEGDMA,UDMA;76.5%) showed the flexural strength of 138MPa and relatively low tensile strength of 25.3MPa. All resin types showed increasing flexural strength with increasing strain rate. Tensile and Flexural strength are dependent on the resin matrix composition, the filler particle size and then the filler volume in that order