Effects of Different Surface Treatments on the Compression-Shear Strength of Cad-Cam Zirconia Posts

Abstract

Aim: Post systems are crucial for the treatment of endodontically treated teeth with excessive crown destruction. Currently, increase in esthetic demands has increased the use of tooth-colored post systems. The aim of this study was to evaluate compression-shear strength after the application of different resin cements and different surface treatments to zirconia post-cores produced by the CAD-CAM milling technique. Methodology: One hundred twenty crown parts of maxillary central incisors were cut using a 2-mm enamel–cement joint using a water-cooled diamond bur in an air turbine handpiece at 300,000 rpm. Root canals with the same diameter were prepared using Gates-Glidden drills and Snowpost system drills. According to the enlarged canal, zirconia posts were prepared by the CAD-CAM copy-milling technique, and the zirconia post surfaces were roughened by different techniques (hydrofluoric acid, Al2O3 partial abrasion, CoJet silica coating). The roughened posts were cemented to the tooth canal using three resin cements: 10- Methacryloyloxydecyl dihydrogen phosphate (MDP)-containing cement, Bis-GMA-based resin, and resin-based adhesive. As the control group, the zirconia post surfaces with no application were fixed using three resin cements. The specimens were set down into 25u25x25 mm fabricated blocks with acrylic resin materials. Compression-shear strength tests of the prepared samples were conducted on the Instron Testing Machine by using appropriate equipment. Results: In summary, the combination of roughening techniques such as Al2O3 partial etching and CoJet silica coating using cement-containing MDP rendered the highest compression-shear strength. Conclusion: This in vitro study proposes the cementation of zirconia post-cores etched by Cojet silica coating and Al2O3 particles using MDP- containing resin cement.