DentAI – Oxygen-Inhibited Layer (OIL)

What is the Oxygen-Inhibited Layer?

• Description: The Oxygen-Inhibited Layer (OIL) — also known as the Air Inhibition Layer and the Oxygen Inhibition Layer — is a layer of resin in which complete polymerization does not occur because of contact with oxygen.
• Cause: Oxygen reacts with the free radicals that initiate the polymerization process; as a result, the free radicals can no longer convert the monomers (the building blocks of the resin) into oligomers and polymers (longer chains), and complete polymerization does not happen.
• Thickness: This layer is usually between 10 and 40 microns thick.

Solutions

• Two solutions have been proposed to address this problem:
• 1. Adding a resin coating: Provide more free radicals by adding a layer of resin coating (RC).
• 2. Using a glycerin layer: Use a layer of glycerin to block oxygen and cure through the glycerin layer.
• Important note: This method should only be used for curing the final resin layer.
• Important note: If a direct restoration is performed in the same session, there is no need to cure the layer (Immediate Dentin Sealing - IDS) or RC through a glycerin layer, because the subsequent resin layers provide the free radicals needed at this stage.

The importance of the Oxygen-Inhibited Layer when building the Biobase

• Description: When building the Biobase using bonding systems that have a thin adhesive layer, attention to the Oxygen-Inhibited Layer (OIL) is important.
• Example — Clearfil SE Protect: This bonding system has a much thinner adhesive layer than Optibond FL.
• Consequence: If a resin coating (RC) is not used, the thin adhesive layer of Clearfil SE Protect may not polymerize significantly (because of the OIL effect).
• Solution: By placing an RC layer, the thickness of the adhesive layer is increased to counteract the effects of the Oxygen-Inhibited Layer in this critical area (the junction of the Biobase).
• Optibond FL: This bonding system has a thicker adhesive layer.
• Consequence: Because of the greater thickness of the Optibond FL adhesive layer, using an additional layer of Optibond FL adhesive itself as the RC layer may be appropriate.