Fracture strength of anterior cantilever resin-bonded fixed partial dentures fabricated from high translucency zirconia with different intaglio surface treatments.

Abstract

To compare the fracture resistance and failure modes of anterior cantilever resin-bonded fixed partial dentures (RBFPDs) fabricated from high translucency zirconia with different intaglio surface treatments. Sound-extracted canines (N=50) were randomly divided into five groups (n=10) to be restored with high translucency zirconia RBFBDs of different intaglio surface treatments. The RBFPD was designed using exocad software and fabricated using a CAM milling machine. The RBFPDs were treated differently: abrasion with 50µm alumina particles (Group 1); abrasion with 30µm silica-coated alumina particles (Group 2); abrasion with silica-coated alumina particles (30µm) and silane application (Group 3); abrasion with silica-coated alumina particles (30µm) and 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primer application (Group 4); abrasion with silica-coated alumina particles (30µm) and silane, and 10-MDP primer application. All RBFPDs were cemented using dual-cured resin cement. The RBFPDs underwent 6000 thermal cycles with distilled water at 5/55°C for 2min per cycle and then mechanical cyclic loading with 1200,000 cycles of 50N at a 1.7Hz frequency at an angle of 135° to the abutment's long axis. Then, RBFPDs were loaded to fracture using a universal testing machine at 1mm/min. Maximum fracture forces and failure modes were recorded. Fractured specimens and uncemented specimens were examined using a scanning electron microscope. Data was analyzed using ANOVA and Games-Howell post hoc tests at p<0.05. Mean fracture load results showed a statistically significant difference between the research groups (p<0.0001) and it ranged from 69.78 to 584N. Group 4 exhibited the highest fracture load mean (p<0.0001) which was significantly different from all other groups. Group 2 recorded a significantly higher fracture load mean than Group 3 (p=0.029). Three modes of failure were observed: prosthesis debonding, prosthesis fracture, and abutment fracture. Abrasion of zirconia surface with 30µm silica-coated alumina particles and application of 10-MDP primer yielded the highest mean fracture loads of monolithic high translucency zirconia RBFPD. The mode of fracture of the RBFPDs was influenced by the type of surface treatments.