Objectives: The aim of this study was to compare the microtensile bond strengths between layers of Filtek P90 bonded with Filtek Z350, Filtek P90 or Vitremer due to the absence of the oxygen inhibition layer on the silorane-based composite and its different components.
Methods: Initially, substrates for the testing specimens were fabricated using a silicone mold (5mm x 5mm x 2.5mm) and light-cured for 40 s (Blue Star 3, Microdont; 1076mW/cm2). According to the testing group, it was used or not an adhesive layer, light-cured for 10 s. The second substrate was applied in a 2.5mm increment and cured for 40 s (Table 1). The specimens were sectioned in beams with 0.64mm2 cross-sectional area and stored in distilled water at 37¼C for 24 h. Microtensile bond strength test was performed using a universal testing machine with a 0.5mm/min crosshead speed. Values were calculated in MPa. Data were analyzed with ANOVA and Tukey's post-hoc tests at a 5% significance level.
Table 1. Tested groups and bond strength results
Group
| Bonding condition
| Bond strength (MPa) |
G1
| P90/P90 adhesive/P90
| 50.9(15.3)abdf * |
G2
| P90/without adhesive/P90
| 40.2(10.2)acfh |
G3
| Z350/without adhesive/Z350
| 62.1(15.2)bdf |
G4
| P90/without adhesive, polyester strip/P90
| 28.8(9.2)cegh |
G5
| Z350/P90 adhesive/P90
| 62.1(8.2)df |
G6
| P90/Single Bond 2/Z350
| 37.1(12.5)aeh |
G7
| Z350/Single Bond 2/Z350
| 54.3(12.3)f |
G8
| Vitremer/Single Bond 2/Z350
| 37.4(7.4)agh |
G9
| Vitremer/P90 adhesive/P90
| 34.9(4.1)h |
*Means with the same letter are statistically the same.
Results: The mean and standard deviations of the microtensile bond strengths data are presented in Table 1. G5 showed the highest mean value (62.1 MPa) and G4 the lowest (28.8 MPa). Significant difference was showed between G2 and G3. No significant difference was found between G8 and G9, G5 and G7, G1 and G6.
Conclusions: Within the limitations of this study, it can be concluded that silorane composite showed similar bonding properties when bonded with methacrylate-based materials. Significantly lower bond strength was observed between layers of P90 than of Z350. Financial support: CAPES/Brazil.