The permeability of resin-dentine bonds is closely related to the mechanical stability of resin-dentine bonds and bonding durability. Water from dentinal tubules, contained in the adhesives or remained after etching and rinsing, together with water from the outside environment are sources of water in the areas of nanoleakage, which leads to decreased resin-dentine bonds. Two aspects related to permeability are thought to improve the mechanical stability of resindentine bonds. One aspect is the reduction of permeability in the dentinal tubules, and the other is the improvement of resin infiltration to the hybrid layer. This review includes the permeability of dentine, infiltration of adhesives in the hybrid layer, and strategies concerning permeability and infiltration to create stable resin-dentine bonds.
