The effects of a multi-step dentin bonding system on dentin permeability

Composite resin was bonded to dentin of crown segments using the multi-step Bowen bonding method. The permeability of the crown segments was measured before and after each step of the procedure to determine their effects on dentin permeability. Treatment of dentin smear layers with ferric oxalate alone reduced dentin permeability by 65%. The use of NTG-GMA or PMDM alone had much less effect on dentin permeability. The combined use of NTG-GMA and PMDM increased dentin permeability. The use of these agents following ferric oxalate treatment reduced permeability. The combined use of these agents followed by composite bonding led to a decrease in dentin permeability, which remained low after breaking the bond for 3 months, the longest time period studied. The ability of a dentin bonding system to seal dentinal tubules and decrease dentin permeability should be an important characteristic of dentin bonding agents.