Marginal Adaptation of Nanofilled, Packable and Hybrid Dental Composite Resins Stored in Artificial Saliva

Resin based composites are possibly the most universal material available in dentistry as they are used in a huge variety of clinical applications, ranging from filling material, luting agent, indirect restorations and metal facing for endodontic posts and cores. The growth of bacteria on the composite resin surfaces, secondary caries and pulp damage or marginal imperfections may occur at the site of gap formation. In this study, marginal adaptation of three composites were measured and compared. A total of sixty human mandibular first molars were used. The teeth were divided into three main groups (20 teeth each) according to the composite resins that were used. In group I, Surefil (packable composite) was used as the restorative material. In group II, Esthet-X-improved (nanofilled composite) was used, while in group III Glacier (hybrid composite) was used. Each group was subdivided into four subgroups (five teeth each) according to the storage intervals (24 hours, one week, two weeks, and three weeks). In each group, occlusomesial cavities were prepared with diamond burs and restored with the composite, according to manufacturer's instructions. In all specimens, composite was applied to the cavity using incremental technique. All the restored teeth were subjected to in vitro thermal cycling and mechanical loading simulating a total of six months in vivo function. Marginal adaptation was evaluated using Measurescope-10 and the results were confirmed with scanning electron microscope. These specimens were dried, sputter coated with gold-palladium and then photographed with SEM at 1500x. A highly significant difference in marginal adaptation was found between the used composites. After specimen storage in artificial saliva, there was a gradual improvement in the marginal adaptability of the specimens. It can be concluded that the marginal adaptation of the nanofilled composite was the best when compared to the other composites.