Randspaltbreiten im Dentin - eine neue Methode zur Evaluation der benötigten Leistungsfähigkeit moderner Adhäsive

The aim of this study was to determine the necessary performance of modern adhesives. To this aim, in-vitro investigations, concerning the marginal gap formation of direct composite-fillings of two diferent types of composites (one nanohybride composite and one bulk-fill composite) were made. In order to assess the necessary adhesive performance which would be able to prevent mikroleakage, a modified conditioning of the cavity was used. In this study 32 human third molars received occlusal-distal and occlusal-mesial class-II slot preparations. The 64 cavities were randomly assigned to eight groups with eight samples each (n = 8). Modified conditioning included phosphoric acid and a light-curing bonding, disclaiming the usage of an adhesive pre-treatment. Depending on the experimental group cavities were filled with Venus Diamond or SDR with diferent incremental thickness. After working-out and polishing of the fillings, marginal quality was assessed under a scanning electron microscope (SEM). Data were evaluated statisically with the program R. How it was expected, all samples showed marginal gap formations as a result of the modified conditioning. Incremental thickness had a significant impact on marginal quality (p ≤ 0,05). The shape of the cavities (round or square) had no significant impact on marginal quality. A significant difference could be observed between the two composites Venus Diamond and SDR in relation of their performance for different increments processed. While the performance for small increments is better with Venus Diamond, for bulk-fill increments of 5 mm significant better results could be reached with SDR (p ≤ 0,05). The results of the study showed that the bulk-fill composite SDR can be used for dental restaurations with no adverse effect for marginal quality. Marginal gap formations are considered as a result of not compensated polymerization shrinkage and polymerization stress of the composite used. In order to prevent marginal gap formation, the usage of effective dentine adhesives is essential. The necessary performance of the adhesive depends upon the composite as well as upon the incremental thickness of the composite-layer. To guarantee a safe adhesion of a restauration on dentine there must be found an adhesive which is is able to compensate polymerization shrinkage of clinical relevant (bulk-fill) increments, realized with a sufficient sticky power without having adverse effects for the marginal quality when it comes to the usage of smaler increments.