Methods: Three glaze materials were developed using commercial glass powders (P25, P54, Pemco, Canada). P25 (0.2g) mixed with P54 (0.02g) to produce (P25/P54). P54 (0.2g) mixed with P25 (0.02g) to produce (P54/P25). P25 (0.2g) mixed with an experimental glass powder (P25/Frit). 82 disc specimens were produced by heat pressing a leucite glass-ceramic (Den-Mat, USA). Group 1 control (10) was sandblasted using 50 micron alumina oxide. Groups 2-4 (10 per group) were coated using P25/frit (group 2), P25/P54 (Group 3) and P54/P25 (Group 4) before sintering. Groups 1-4 were etched for 2 minutes using 9.5% HF. Composite cylinders (Marathon® v, Den-Mat) were light cured and bonded to the glazed and prepared disc surfaces. Groups were water stored (8 days) before Shear bond strength (SBS) testing at 0.5 mm/minute. Disc specimens (42) were tested using the biaxial flexural strength (BFS) test at a crosshead speed of 0.15mm/min. Group 5 was tested as pressed (21) and Group 6 (21) after coating the tensile surface with P25/frit. Xrd and Sem analyses were carried out.
Results: Mean SBS (MPa ± SD) were: Group 1: 10.7 ± 2.1; Group 2: 9.8 ± 1.9; Group 3: 1.8 ± 1.0 and Group 4: 2.6 ±1.7. Groups 1 and 2 were statistically different to groups 3 and 4 (p < 0.001). There was no difference between groups 1 and 2 or between 3 and 4 (p > 0.05). Mean BFS (MPa ± SD) of group 6 (200.2 ±22.9) was statistically different (p < 0.001) to Group 5 (150.2 ± 14.3).
Conclusions: The P25/Frit glaze increased the biaxial flexural strength of the leucite glass ceramic (p < 0.001) and had comparable shear bond strength to an etched and bonded control.