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Indirect versus direct bonding: bond strength and failure location.
1University of Florida College of Dentistry, Gainesville.
Summary
Direct and indirect orthodontic bracket bonding showed similar strengths, but indirect bonding resulted in less resin on teeth. Sealing voids in indirect bonds is crucial for optimal strength.
Area of Science:
- Orthodontics
- Dental Materials Science
- Biomaterials
Background:
- Orthodontic bracket bonding is essential for treatment efficacy.
- Direct and indirect bonding techniques offer different clinical advantages and challenges.
- Understanding bond strength and failure modes is critical for material selection and clinical practice.
Purpose of the Study:
- To compare bond strengths and failure locations of direct versus indirect orthodontic bracket bonding.
- To evaluate the impact of marginal voids on bond strength in indirect bonding.
- To assess the clinical implications of sealing voids in indirect bonding.
Main Methods:
- In vitro study using extracted human premolars.
- Direct bonding with composite resin.
- Indirect bonding utilizing silicone positioners and two-part unfilled resin.
- Assessment of bond strength and failure interface analysis.
Main Results:
- No significant difference in bond strength between direct, void-free indirect, and sealed indirect bonds.
- Indirect bonds with marginal voids were significantly weaker (half the strength).
- Direct bonds predominantly failed at the bracket-adhesive interface (44%).
- Indirect bonds mainly failed at the enamel-resin interface (72%).
Conclusions:
- Indirect bonding offers comparable bond strength to direct bonding.
- Sealing marginal voids in indirect bonding is essential to maintain bond integrity.
- Indirect bonding may facilitate easier debonding with less residual resin on enamel.