IADR Abstract Archives
The Effect of Home Bleaching Agents on the Vickers Hardness and Surface Topography of Polished and Unpolished CAD/CAM Composite Materials
Objectives: to investigate the effect of home bleaching agents on the Vickers hardness and surface topography of polished and unpolished CAD/CAM composite materials.
Methods: Four resin composite blocks (RCB), Grandio blocs (Gr), Lava™ Ultimate (Lu), BRILLIANT Crios (Bc) and Cerasmart (Cs), and a polymer-infiltrated ceramic network (PICN) block, Enamic (En), were prepared (14 mm × 12 mm × 2 mm) before undergoing home bleaching procedure using Opalescence 15% for 8 h and 56 h. The specimens were randomly divided into two groups, unpolished or polished. The micro-hardness of each specimen (n=4) of each group was measured before bleaching, at 8 h and 56 h of bleaching period, 24 h post-bleaching, and one-month post-bleaching using a Vickers micro-hardness instrument with a load of 300 gf for 20 s. Surface topography was investigated using a stylus contact profilometer (n=4) and a scanning electron microscope (n=3) at x40 k magnification. Data were statistically analysed using two-way and one-way ANOVA, the Tukey’s post hoc, and independent t-test.
Results: Polished samples exhibited hardness reduction after 8 hours of bleaching which was the most for En followed by Gr, Lu, Cs and Bc, with significant difference between all materials except for Cs and Lu. After 56 h, hardness reduction was the most for En followed by Gr, Lu, Bc and Cs, with significant difference between all materials except Bc and Cs. For unpolished group the following order was noticed: En followed by Lu, Gr, Bc and Cs, after 8 h of bleach and En followed by Lu, Gr, Cs and Bc, with significant difference between all materials except for Bc and Cs after 56 h of bleach. At 24 h and 1 month post-bleaching similar hardness reduction order was noted. Further, there was significant difference in hardness reduction between polished and unpolished groups for all investigated materials. There was a significant material and time effect with a significant interaction for hardness reduction (p<0.0001).
Conclusions: Home bleaching significantly influenced the Vickers hardness of the polished and unpolished CAD/CAM composite blocks, with PICN exhibiting the most hardness reduction among all composite blocks. Further, Home bleaching significantly influenced the surface roughness of both polished and unpolished CAD/CAM composite blocks.
Methods: Four resin composite blocks (RCB), Grandio blocs (Gr), Lava™ Ultimate (Lu), BRILLIANT Crios (Bc) and Cerasmart (Cs), and a polymer-infiltrated ceramic network (PICN) block, Enamic (En), were prepared (14 mm × 12 mm × 2 mm) before undergoing home bleaching procedure using Opalescence 15% for 8 h and 56 h. The specimens were randomly divided into two groups, unpolished or polished. The micro-hardness of each specimen (n=4) of each group was measured before bleaching, at 8 h and 56 h of bleaching period, 24 h post-bleaching, and one-month post-bleaching using a Vickers micro-hardness instrument with a load of 300 gf for 20 s. Surface topography was investigated using a stylus contact profilometer (n=4) and a scanning electron microscope (n=3) at x40 k magnification. Data were statistically analysed using two-way and one-way ANOVA, the Tukey’s post hoc, and independent t-test.
Results: Polished samples exhibited hardness reduction after 8 hours of bleaching which was the most for En followed by Gr, Lu, Cs and Bc, with significant difference between all materials except for Cs and Lu. After 56 h, hardness reduction was the most for En followed by Gr, Lu, Bc and Cs, with significant difference between all materials except Bc and Cs. For unpolished group the following order was noticed: En followed by Lu, Gr, Bc and Cs, after 8 h of bleach and En followed by Lu, Gr, Cs and Bc, with significant difference between all materials except for Bc and Cs after 56 h of bleach. At 24 h and 1 month post-bleaching similar hardness reduction order was noted. Further, there was significant difference in hardness reduction between polished and unpolished groups for all investigated materials. There was a significant material and time effect with a significant interaction for hardness reduction (p<0.0001).
Conclusions: Home bleaching significantly influenced the Vickers hardness of the polished and unpolished CAD/CAM composite blocks, with PICN exhibiting the most hardness reduction among all composite blocks. Further, Home bleaching significantly influenced the surface roughness of both polished and unpolished CAD/CAM composite blocks.