IADR Abstract Archives
Contraction Stress of Adhesive Agents Bonded to Dentin
Objective: The aim of this study was to investigate the concerted action of dentin and adhesive agents on the setting contraction stress development. Methods: The adhesive resin was placed in a thin layer between a glass plate and parallel to it the flat surface of a dentin cylinder in a tensilometer. The contraction stress was determined continuously from the start of light curing up to 30 minutes. Two total-etch systems: Excite (Ivoclar) and One-Step Plus (Bisco) and two systems with self-etching primers: Protect Bond and Liner Bond 2V (Kuraray) were used. Measurements were also conducted on these adhesives combined with the composite Z250 (3M Espe) in a 1 mm thick layer. Results: All contraction stress curves showed a maximum at approximately 1-2 minutes after the start of light curing. Thereafter the stress decreased dramatically for the total-etch adhesive systems and to a lesser extend for the adhesives with self-etching primers. The stress decrease was reflected in the curves for the adhesives combined with Z250 (Table).
|
Test group (n=12) |
Contraction stress MPa(SD) |
Stress decrease % |
|
|
|
At maximum |
At 30 min |
From max to 30 min |
|
Excitea |
4.0(1.0) |
0.9(0.7) |
78 |
|
One-Step Plusa |
1.9(1.1) |
0.2(0.3) |
89 |
|
Clearfil Protect Bondb |
2.8(0.7) |
2.0(0.6) |
29 |
|
Clearfil Liner Bond 2Vb |
3.3(1.1) |
2.2(0.9) |
33 |
|
Excitea + Z250 |
3.2(0.7) |
2.9(0.7) |
9 |
|
One-Step Plusa + Z250 |
3.8(1.0) |
3.3(0.8) |
13 |
|
Clearfil Protect Bondb + Z250 |
3.5(0.8) |
3.2(0.7) |
9 |
|
Clearfil Liner Bond 2Vb + Z250 |
3.7(1.1) |
3.5(1.1) |
5 |
|
a = Total-etch system; b = System with self-etching primer. |
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Conclusion: The greater stress decrease for the total-etch systems may be caused by the opened dentinal tubules from which water and/or solvents are released into the adhesives by the pulling/sucking action of the contraction stress. This happens less with the adhesives with self-etching primers where the tubules mainly remain closed.