Surface treatment and storage time affect bonding to zirconia

Researchers from NIOM have tested how time between surface treatment and cementation influences bonding to zirconia restorations.

“These results highlight that timing is part of the bonding procedure, not just the materials and techniques we choose,” says dentist and scientist Mina Aker Sagen at NIOM.

What is this about?

Zirconia is widely used in restorative dentistry, but achieving reliable bonding to zirconia remains a clinical challenge. Surface treatments such as airborne particle abrasion (APA) or chemical etching are commonly used to improve adhesion before cementation.
In this study, researchers investigated how the time between surface treatment and cementation affects two key factors: surface free energy and bond strength between zirconia and composite cement.

What did the researchers find out?

The study compared two surface treatment methods: APA and hot etching with potassium hydrogen difluoride. Specimens were stored for different time intervals after treatment: immediately, 24 hours, one week, and one month.

The results showed that surface free energy decreased over time for both treatment methods. Chemically etched zirconia showed higher surface free energy overall, but this advantage also declined with storage.

Bond strength was, to some extent, influenced by storage time. For chemically etched zirconia, bond strength was higher after one week compared to immediate testing. However, longer storage was also associated with more adhesive failures at the interface.

What are the key results/main findings?

The findings indicate that time plays a role in how well zirconia bonds to composite cement. Even though different surface treatments affect surface properties, delaying cementation may reduce the effectiveness of the treatment.