To compare the immediate and 24 hour shear bond strength values of an experimental universal adhesive and a commercially available universal adhesive (Scotchbond Universal, 3M ESPE) by three experienced operators.
Method:
Human molars were sectioned, mounted and ground to a flat dentin or enamel surface using 600 grit silicon carbide paper. Three groups of 5 specimens were tested by each of the three operators for each adhesive:
Group 1: Self-etch to dentin, tested after 60 seconds; Group 2: Self-etch to dentin after 24 hours Group 3: Self-etch to enamel after 24 hours.
Adhesives were applied to the dentin or enamel surface according to manufacturer’s instructions. Specimens were placed in the Ultradent jig. Composite (Tetric EvoCeram Bulkfill, Ivoclar Vivadent) was applied via the nylon insert. The specimens were light cured for 20 seconds, removed from the jig and loaded in the Instron Universal Testing Machine using a 1KN load cell with a crosshead speed of 1.0 mm/min. They were either tested immediately or stored in the incubator at 37°C in 100% humidity for 24 hours prior to loading.
Result:
Shear bond strength values (MPa).
Experimental Adhesive (EA) |
Scotchbond Universal (SU) |
|||||
Dentin 60s |
Dentin 24h |
Enamel 24h |
Dentin 60s |
Dentin 24h |
Enamel 24h |
|
Operator 1 |
29.3±6.2 |
47.8±1.8 |
21.9±3.5 |
29.2±4.4 |
42.7±7.4 |
13.0±5.1 |
Operator 2 |
26.3±6.9 |
43.6±7.3 |
20.9±7.8 |
27.3±5.9 |
30.8±2.8 |
13.7±3.3 |
Operator 3 |
28.9±1.5 |
42.6±4.9 |
21.6±7.7 |
31.0±1.8 |
47.9±3.1 |
17.2±4.7 |
Data was analyzed by one-way univariate analysis of variance (ANOVA), p < 0.05. Follow up multiple comparisons (Tukey HSD) were performed.
Conclusion:
There was a statistically significant difference in shear bond strength to enamel after 24 hours for EA compared to SU for all Operators. There was no statistically significant difference in bond strength between Operators with the exception of Operator 2 for SU on dentin after 24 hours.