Objectives: The purpose of this in vitro study was to evaluate the shear bond strength of self-adhesive resin cements to dentin, enamel, and etched enamel.
Methods: Extracted third molars were sectioned mesiodistally exposing dentin, or sectioned flat on the proximal surface for enamel, and wet ground with 600 grit silicon carbide abrasive. Sections were mounted in PMA tray material and ten sections were randomly assigned to each test group. The tooth substrate was prepared according to each cement manufacturer's instructions. The etched enamel sections were etched for 20sec with 37% phosphoric acid. Ceramic rods (eMax Press/Ivoclar) were etched with 4.9% hydrofluoric acid, rinsed, dried, and silanated (Monobond Plus/Ivoclar) prior to bonding. The ceramic rod was cemented to the tooth substrate, held in place with a clamp (Ultradent Products Inc), and light polymerized with a VLC curing unit. Bonded specimens were stored (370C, 10min) prior to testing. Shear bond failure was measured with an Instron testing machine at a load rate of 0.5mm/min until failure.
Results:
Cement | Dentin | Enamel | Etched Enamel |
MultiLink | 26.61±3.93 A | 22.10±1.39 A | NA |
SpeedCem | 14.27±2.51 B | 14.43±4.6 B | 23.83±8.30 A |
Unicem | 6.55±2.34 C | 14.54±2.51 B | 16.89±4.20 AB |
Bifix SE | 6.26±1.94 C | 9.11±3.63 C | 16.53±5.37 B |
MaxCem Elite | 4.46±2.18 C | 6.53±2.40 C | 21.89±6.59 AB |
Clearfil SA | 2.60±1.07 D | 7.29±1.69 C | 9.48±1.66 C |
The data (MPa) was subjected to an ANOVA test and a Tukey test was used to determine significant differences between cements. Letters identify significantly different groups (p<0.05).
Conclusion: There was a significant difference in shear bond strength of cements on all substrates. There was no significant difference in shear bond strength between unprepared and etched enamel for Unicem and ClearFil SA. All other cements had a significant increase in shear bond strength when the enamel was etched. This project was supported by Ivoclar Vivadent.