Methods: 3mm x 6mm cylindrical molds were filled with Vitrebond Plus RMGI. Samples were then treated in one of two ways: 1) RMGI surfaces were treated with 35% phosphoric acid (N=27) or 2) RMGI surfaces were not treated with phosphoric acid (N=26).
Within each category, all samples were treated with ExciTE® F total-etch bonding agent. Separate cylindrical molds (8mm x 3mm) were then placed over the RMGI samples and 3 mm of Filtek Supreme Ultra was added to each sample.
The composite resin side of the buttons were embedded in acrylic molds and these molds were kept at room temperature for 24 hours. All experimental samples were created following manufacturers’ instructions. The shear bond strength of each button was determined using a universal testing machine (Instron® 5566A) at a crosshead speed of 1.0 mm/min. Data was analyzed via the independent-samples t-test. A p-value <0.05 was considered statistically significant.
Results:
Group statistics
Group |
N |
Mean (MPa) |
SD (MPa) |
Etched |
27 |
3.17 |
1.97 |
Non-etched |
26 |
3.22 |
1.84 |
No statistically significant difference was observed between the acid-etched and non-etched groups (p=0.918).
Conclusions: Literature review shows some clinicians selectively etch RMGI and this study shows there is no statistically significant effect on the bond strength between Vitrebond Plus and Filtek Supreme Ultra. Further research is warranted to ensure etching RMGI does not increase microleakage when using these two products.