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Shear bond strength of self-ligating brackets
Maria Francesca Sfondrini1, Sara Gatti, Andrea Scribante
1Department of Orthodontics, University of Pavia, Italy.
European Journal of Orthodontics
|July 28, 2010
Summary
This study compared conventional and self-ligating orthodontic brackets, finding that self-ligating types (Smart Clip and Damon 3MX) exhibited superior shear bond strength (SBS) and adhesive remnant index (ARI) scores, indicating better clinical performance.
Area of Science:
- Orthodontics
- Biomaterials Science
- Dental Materials
Background:
- Orthodontic bracket selection impacts treatment efficiency and outcomes.
- Understanding the bond strength and failure modes of different bracket types is crucial for clinical success.
Purpose of the Study:
- To compare the shear bond strength (SBS) and adhesive remnant index (ARI) of conventional stainless steel brackets with three types of self-ligating brackets.
- To evaluate the clinical adequacy of bond strength for all tested bracket systems.
Main Methods:
- Four groups of 20 bovine enamel specimens were bonded with either conventional (Step) or self-ligating (Smart Clip, Quick, Damon 3MX) brackets.
- An adhesive system (Ortho Solo primer, Transbond XT resin) was used for bonding.
- Shear bond strength was tested using an Instron universal testing machine.
- Adhesive failure rates were analyzed using chi-square tests.
Main Results:
- Self-ligating brackets (Smart Clip and Damon 3MX) demonstrated significantly higher shear bond strength (SBS) compared to conventional brackets and the Quick self-ligating bracket.
- Conventional brackets and the Quick bracket showed a higher frequency of ARI score 1 (enamel fracture), while Smart Clip and Damon 3MX showed a higher frequency of ARI score 2 (adhesive fracture with some enamel).
- All tested bracket systems exhibited clinically adequate SBS.
Conclusions:
- Passive and interactive self-ligating brackets, specifically Smart Clip and Damon 3MX, offer superior shear bond strength compared to conventional brackets.
- The choice of self-ligating bracket system can influence bond failure modes, with some systems showing a tendency towards adhesive failure over enamel fracture.
- All evaluated bracket types provide sufficient bond strength for clinical orthodontic applications.
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