Objectives: The technique of sealing the exposed dentin with resin-based adhesives prior to impression taking has been recommended to establish a peripheral seal in order to preserve the health of the pulpodentinal complex. This study tested the hypothesis that all-in-one adhesives are effective in minimizing dentin permeability after in vivo tooth preparation procedures.
Methods: Crown preparations in vital human teeth were sealed with Xeno III (XE, Caulk-Dentsply), Adper Prompt (AP, 3M ESPE), One-Up Bond F (OU, Tokuyama) and iBond (IB, Heraeus-Kulzer). After removal of the oxygen inhibition layer from the cured adhesives, epoxy resin replicas were produced from polyvinyl siloxane impressions for SEM examination. They were compared with epoxy resin replicas of crown preparations that were bonded with these all-in-one adhesives, followed by the application of an additional low viscosity resin-coating (Scotchbond Multi-Purpose Plus resin, 3M ESPE). Epoxy replicas reproduced from crown preparations with intact smear layers (i.e., without adhesive application) were used as the control.
Results: Resin replicas of in vivo crown preparations revealed sporadic regions along the surfaces of the adhesive-coated dentin in which there was swelling of the adhesive. When the all-in-one adhesives were used on their own, transudation of dentinal fluid droplets could be universally identified from the surfaces of all resin replicas examined. Dentinal fluid transudation in iBond and One-Up Bond F was similar to, and that of Xeno III and Adper Prompt was more profuse than the control smear layer-covered dentin. Fluid transudation was not evident when an additional resin-coating was used after the application of the all-in-one adhesives.
Conclusions: The intrinsic permeability of all-in-one adhesives does not permit hermetic seal of vital human dentin. As better seal is achieved by converting these adhesives to two-step self-etch adhesives, one is compelled to ask: reducing steps in dentin bonding – what have we really gained?