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Effect of Cyclic Loading on Shear Bond Strength of Orthodontic Brackets: An In Vitro Study
Mohammad Moslem Imani1, Farzaneh Aghajani2, Nafiseh Momeni3
1Assistant Professor, Department of Orthodontics, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Journal of Dentistry (Tehran, Iran)
|March 8, 2019
Summary
Cyclic loading simulating mastication did not significantly affect orthodontic bracket shear bond strength (SBS) in either self-etch or total-etch systems. However, cyclic forces did alter the adhesive remnant index (ARI) scores, indicating changes in bond failure patterns.
Area of Science:
- Dental Materials Science
- Orthodontic Adhesion
- Biomaterials Engineering
Background:
- Orthodontic brackets undergo stress from mastication and intraoral forces.
- Understanding the impact of these forces on bracket bond strength is crucial for clinical success.
Purpose of the Study:
- To evaluate the effect of simulated masticatory cyclic loading on the shear bond strength (SBS) of metal brackets.
- To compare the performance of self-etch and total-etch bonding systems under cyclic stress.
Main Methods:
- 84 bovine incisors were bonded with self-etch or total-etch systems.
- Samples underwent thermocycling and cyclic loading (40 N, 2 Hz, 10,000 cycles) to simulate mastication.
- Shear bond strength (SBS) and adhesive remnant index (ARI) were measured.
Main Results:
- Cyclic loading did not significantly impact SBS for either bonding system (P>0.05).
- Total-etch systems showed higher SBS than self-etch systems, though not statistically significant in the context of cyclic loading.
- Cyclic loading significantly affected ARI scores (P<0.05).
Conclusions:
- Simulated low-intensity masticatory forces over 10,000 cycles do not significantly weaken bracket-adhesive bonds.
- Cyclic loading influences how the adhesive fails (ARI), but not the overall bond strength.
- Both self-etch and total-etch systems demonstrated clinically acceptable performance.
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