Low-shrinkage composites: an in vitro evaluation of sealing ability after occlusal loading.

The objective of this in vitro study was to compare the microleakage of a flowable low-shrinkage-stress resin composite--in a Class II fatigue-loading design when used as a 4 mm dentin replacement--to a conventionally layered silorane-based resin composite. Eighty standardized 4 mm deep cavities, divided into 4 subgroups, were restored with the 2 tested materials. Half of the restorations were submitted to mechanical loading, and all of the restorations were prepared for microleakage evaluation. The evaluation of the marginal adaptation to dentin was performed with scanning electron microscopy. The results showed that both silorane-based composite groups had higher rates of microleakage in comparison to the low-shrinkage-stress resin composite groups.