EFFECT OF MODIFICATION IN RESIN MATRIX AND TECHNIQUE OF PACKING ON POLYMERIZATION SHRINKAGE OF COMPOSITE RESIN

Abstract

Composite materials and adhesive techniques have become the foundation of modem dentistry and composite are one of the most heavily researched dental materials today. Therefore, this study was designed to investigate the influence of modification in resin matrix on the polymerization shrinkage of composite resin. The parameters of the study were to assess the effect of the technique of packing on polymerization shrinkage of composite resin. Furthermore, to determine the effect of aging on polymerization shrinkage of composite resin. Two composite resin materials were used in this study. The first contained two-resin matrices, namely; Bis-GMA (Bisphenol A-diglycidyl ether dimeth acrylate) and TEGDMA (tri [ethylene glycol] dimethacrylate. The second composite resin was formed of three resins namely TEGDMA, UDMA (urethane dimeth acrylate) and Bis-EMA (Bisphenol apolyethylene glycol diethr dimeth acrylate). The study was divided into three parts, in the first part i.e., rnicrometric assessment, a total of 40 specimens were prepared. They were divided into two groups relative to the type of composite resin used. The first group was for the two-resin containing composite, while the second group was for the three-resin containing composite. Each group was subdivided into two equal subgroups-relative to the technique of composite resin packing used, i.e., in the first subgroup the composite resin was packed with conventional incremental packing technique, while in the second subgroup the ultrasonic packing technique was utilized.