Glasfaserverstärkte Komposite: Eine In-vitro-Studie zur Beurteilung der Belastungsfähigkeit im Vergleich zu einem herkömmlichen Komposit

1.2.1 Background and aims of this study Fiber Reinforced Composites (FRCs) are dental filling composites that are used for great posterior restaurations. They are characterized by their biomimetic behavior and have been developed to inhibit marginal leakage and to stop crack propagation due to high chewing forces by imitating the stress-absorbing properties of the dentin-enamel junction. The aim of the present in-vitro-study is to evaluate the fracture strength of two FRCs (XENIUS® base and everX Posterior™) and a conventional composite (Heliomolar®) with regard to marginal integrity before and after thermo-mechanical loading (TML). 1.2.2 Material and methods 40 extracted intact human third molars were prepared with a deep mesio-occluso-distal preparation and the major cusps were reduced by 3 mm. The teeth were divided into five groups (n=8) and filled with different composites (group 1: pure Heliomolar®; group 2: pure XENIUS® base; group 3: pure everX Posterior™; group 4: XENIUS® base body and 2 mm Heliomolar® cover; group 5: everX Posterior™ body and 2 mm Heliomolar® cover). To prevent dehydration, the teeth were stored in a 0.1 % thymol solution. The roots have been shortened by 3 mm apical the dentin-enamel junction. To form replicas, dental impressions were made before and after thermo-mechanical loading (100000 x 50 N and 2500 thermocycles between 5 and 55 °C). The marginal integrity of the approximal filling section has been evaluated through a scanning-electron-microscope (SEM) imaging a magnification of 200. The results were statistically analyzed with SPSS 17.0 (Superior Performing Software System). 1.2.3 Results The artificial aging of the teeth with TML led to a significant disimprovement of the marginal adaptation in all testet groups. The teeth of group 2 (pure XENIUS® base) exhibited the significantly worst results of marginal adaptation (79.2 %). The teeth of group 3 (pure everX Posterior™) showed a 85.2 % adaptation. Group 1, 4 and 5 showed better results. With extensive class-II cavities, the combination of everX Posterior™ and the composite Heliomolar® (group 5) revealed a marginal integrity of 90.3 %. The use of a common composite (group 1) exhibited a continuous margin of 92.3 %. The teeth of group 4 had the best results with a perfect margin of 94.3 %. The results before TML showed a perfect margin of 100% in all five groups. 1.2.4 Practical conclusions Within this in-vtro-study, it can be concluded that the application of fibre-reinforced composite does not lead to statistically significant improvement of the fracture toughness of molar teeth with extensive class-II cavities, compared to the use of a conventional composite.