Effectiveness of protecting a zirconia bonding surface against contaminations using a newly developed protective...

The purpose of this study was to test the effectiveness of a newly developed lacquer and its ability to protect pre-conditioned bonding surfaces of zirconia ceramic against contamination with saliva or silicone remnants.

Disk-shaped zirconia ceramic specimens were conditioned and cleaned using air-abrasion. Before contamination with saliva or silicone, a newly developed protective lacquer (1% ethyl cellulose in ethanol) was applied to the bonding surface. After contamination, all specimens of the test groups were cleaned in an ultrasonic bath filled with 99% ethanol for 3 min and then air-dried. A universal primer (Monobond Plus) was applied to the surfaces and then the specimens were bonded to composite resin filled acrylic tubes using a luting resin (Multilink Automix). Each group (n=16) was divided into 2 subgroups (n=8). One subgroup was stored for 3 days in 37°C tap water and the other subgroup was stored for 150 days in 37°C tap water interrupted by 37,500 thermal cycles between 5°C and 55°C. After the storage, the bond strength was measured using a material testing machine.

The specimens of the test groups showed comparable bond strengths to the positive control group after short-term storage. After artificial aging, bond strengths of the test groups were statistically significantly lower compared to the positive control and were statistically significantly higher compared to the negative control groups.

Overall, the use of the newly developed protective lacquer appears to be a promising approach to protect pre-conditioned surfaces of zirconia ceramics against contamination.