New strategy for overcoming microleakage: an elastic layer for dental caries restoration.

An elastic layer fabricated by photo-crosslinked polyurethane (PU) is introduced for the first time for dental composite restoration. The introduction of this layer can effectively inhibit water permeation through the dental adhesive layer to the resin composites for its perfect hydrophobic property and its excellent elastic property. The results show that only minimum microleakage was observed in the experimental group (composite restoration with elastic layer), while significant microleakage was observed in the control group. This new concept based on this elastic layer is first presented for the first time in the composite restoration field. This study may shift the future research focus from increasing the mechanical properties of dental resin composites to an alternative solution for limited restoration lifetime based on the use of an elastic layer intermediate between the composite adhesive and the dental tissue.