Structural Alterations of Zirconia Depending on Sintering Parameters and Effects on Bond Strength After Different Surface Treatments
Cumhuriyet Dental Journal
Objectives: Zirconia having different physical and optical properties is obtained after the application of different sintering parameters. This study aims to investigate structural variations after administering different sintering protocols and to evaluate the effect of different surface treatments on shear bond strength. Materials and Methods: Eighty translucent zirconia specimens (7x3 mm) were divided into two different sintering groups (1480 0 C for 180 min; 1510 0 C for 30 min), then
... d into four subgroups according to surface treatments: control, sandblasted, Er-YAG, and Nd-YAG (n:10). One specimen from each group was analyzed with XRD and one from each subgroup was analyzed with SEM. Ceramics (5x3 mm) were fired onto the zirconia for shear bond strength test using universal testing machine and the failure mode was determined by using stereomicroscope. Translucency and contrast ratio were measured by using spectrophotometer, and biaxial flexural strength test performed by employing universal testing machine on specimens with a diameter (15x1,3 mm) from each sintering group (n:10). Data was analyzed by using two-way ANOVA and Bonferroni Post hoc tests (p<.05). Results: The short sintering group showed higher biaxial flexural strength (943.87±48.69 MPa). The highest surface roughness values were obtained in short sintering groups and within the groups Nd-YAG application was found the most effective method (4.11±0.28 Ra). The highest bond strength value was obtained in sandblasted short time sintered group (29.71±2.52 MPa). The translucency and contrast ratio showed no significant difference. Conclusions: Although a physically stronger zirconia is obtained by short sintering process, long-term sintered zirconia forms a more durable bond strength with ceramics. Sandblasting improve the ceramic-zirconia bond strength may have more benefits than the use of Er-YAG, and Nd-YAG lasers.