Effects of surface properties on bond strength between layers of newly cured dental composites

The shear strength was measured of a polymerizing increment to a newly cured composite increment of the same material with various surface properties. The results showed that the materials with the original surface which had been cured against a cover glass resulted in a significantly higher bond strength than any of the other preparations. It was concluded that the unreacted double bonds (due to the oxygen inhibition) functioned as a bonding medium between two increments of dental composites. The process which impaired the original cured surface decreased the bonding between increments.