Methods: Matrix finished specimens of each resin-modified glass ionomer cement (RMGIC) (Fuji II LC, Photac Fil, and Ketac Nano) were fabricated, stored (37°C, 1d), and randomly divided into two groups (G1 and G2; n=6). Specimens in G1 were treated with 9.5% hydrogen peroxide (PolaDay) and in the G2 with 37.5% hydrogen peroxide (PolaOffice), on just one side. The other side of the specimens was used as a control. In G1 the bleaching product was applied to the top surface of the specimens for 30 min per day for 21 days. In G2 a total of 24 min bleaching session was conducted at one-week intervals. The samples were stored in distilled water (37°C). Surface roughness (Ra) and contact angle measurements were carried out using Surftest SJ-210 (Mitutoyo, Kanagawa, Japan) and Ramé-Hart (Mountain Lakes, U.S.A), respectively, before and after 1, 2, and 3 weeks of bleaching sessions. Data was statistically analyzed (ANOVA, Tukey’s, p<0.05).
Results: Contact angle testing shows an increase in wettability for G2, but not for G1. The table below shows mean Ra values and standard deviations (p<0.05) of the three materials after the various bleaching sessions.
|
Control |
Week 1 |
Week 2 |
Week 3 |
|
Fuji II LC |
9.5% HP |
0,151 ± 0,03 |
0,196 ± 0,03 |
0,134 ± 0,03 |
0,245 ± 0,02 |
37.5% HP |
0,137 ± 0,02 |
0,199 ± 0,05 |
0,141 ± 0,04 |
0,160 ± 0,04 |
|
Photac Fil |
9.5% HP |
0,210 ± 0,02 |
0,226 ± 0,06 |
0,203 ± 0,03 |
0,203 ± 0,03 |
37.5% HP |
0,210 ± 0,02 |
0,233 ± 0,03 |
0,192 ± 0,02 |
0,214 ± 0,02 |
|
Ketac™ Nano |
9.5% HP |
0,421 ± 0,22 |
0,375 ± 0,25 |
0,779 ± 0,43 |
0,273 ± 0,20 |
37.5% HP |
0,408 ± 0,28 |
0,819 ± 0,29 |
0,647 ± 0,48 |
0,530 ± 0,199 |
|
Conclusions: G1 and G2 means are significantly different (p<0.05). The RMGIC had a surface degradation after being exposed to the bleaching agents.