Monday, August 16, 2010

Effect of air-abrasion on the retention of zirconia ceramic crowns luted with different cements before and after artificial aging

A question that is always popping up is what do you use to cement zirconia crowns? This reasearch tries to help answer that question. MJ

 

Effect of air-abrasion on the retention of zirconia ceramic crowns luted with different cements before and after artificial aging

 

Dental Materials

Volume 26, Issue 9, Pages 922-928 (September 2010)

Ramez Shahin, Matthias Kern

Abstract 

Objectives
The purpose of this in vitro study was to evaluate the effect of intaglio surface air-abrasion on the retention of CAD/CAM produced zirconia ceramic crowns cemented with three different types of cement. In addition the influence of artificial aging in masticatory simulator and thermocycling was tested.
Methods
Extracted human premolars were prepared for all-ceramic crowns (12° taper, 3mm axial length). CAD/CAM zirconia crowns were manufactured. Half of the crowns were air-abraded with 50μm alumina particles at 0.25MPa, the rest was left as machined. The crowns were luted with zinc phosphate cement (Hoffmann), glass ionomer cement (Ketac Cem), or composite resin (Panavia 21), subgroups were either stored for 3 days in 37° water bath or stored for 150 days in 37° water bath, with additional 37,500 thermal cycles (5–55°) and 300,000 cycles dynamic loading with 5kg in a masticatory simulator. Then crown retention was measured in tension at a crosshead speed of 2mm/min using a universal testing machine. Statistical analysis was performed with three-way ANOVA.
Results
Mean retention values were ranged from 2.8 to 7.1MPa after 3 days and from 1.6 to 6.1MPa after artificial aging. Air-abrasion significantly increased crown retention (p<0.001), while artificial aging decreased retention (p=0.017). In addition, the luting material had a significant influence on retention (p<0.001) with the adhesive luting resin providing the highest retention.
Significance
The use of phosphate monomer containing composite resin on air-abraded zirconia ceramic can be recommended as most retentive luting method.

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