Objective: The purpose of the study was to compare the shear bond strength of three adhesives used in the self-etch mode to enamel and dentin before and after thermocycling.
Method: Freshly extracted intact (no caries or cracks) human molars (n=120) were flattened with a model trimmer and then wet-ground with SiC discs (60,180 & 320-grit) to obtain flat enamel and dentin surfaces. Teeth were randomly divided into three groups; each adhesive was applied according to manufacturer’s instructions. A Teflon tube (1.5mm diameter) filled with Clearfil AP-X (Kuraray) composite resin was placed over the bonding area and cured with Ivoclar Bluephase curing light (950-1000mW/cm²) for 20s from four directions in standard mode. Samples were stored in distilled water (370C/24 hrs). Half the samples were thermocycled (5º-50ºC/15s dwell time/10,000cycles) the remainders were debonded at 24 hours. All samples were placed into a steel fixture mounted in the Instron Universal Testing machine, subjected to shear loading until failure using a 1mm/min crosshead speed. Data were analyzed using a 2 Factor ANOVA and Tukey post hoc tests (p=0.05).
Results: MPa (Mean±SD) (n=10/group)
Adhesive |
Adhesive monomer |
Etching application |
Enamel |
Dentin |
||
24 hour |
Thermocycled |
24 hour |
Thermocycled |
|||
Clearfil SE Bond 2 |
MDP |
Self-etch |
32.6±8.1 |
34.2±8.3 |
44.4±10.44 |
40.1±10 |
Optibond XTR |
GPDM |
Self-etch |
31.9±6.6 |
32.7±8.3 |
35.0±9.6 |
38.4±7.1 |
SBU |
MDP |
Self-etch |
28.0±7.4 |
31.1±9.3 |
35.2±12.1 |
33.2±9.2 |
Conclusion: The Clearfil SE Bond 2 adhesive had significantly greater shear bond strength to dentin even after thermocycling (p<0.05).
Keywords: Shear Bond Strength, Dentin and Enamel.