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Interlayer formation and its effect on debonding polycrystalline alumina orthodontic brackets
P K Sinha1, M D Rohrer, R S Nanda
1University of Oklahoma, Department of Orthodontics, Oklahoma City, USA.
Summary
Indirect bonding techniques for ceramic orthodontic brackets reduce bracket failure and enamel damage during debonding. This is due to a resin interlayer that facilitates easier removal, minimizing risks associated with direct bonding methods.
Area of Science:
- Dental Materials Science
- Orthodontic Technology
- Biomaterials Engineering
Background:
- Debonding ceramic orthodontic brackets can cause enamel damage.
- Indirect bonding techniques create a resin interlayer, unlike direct bonding.
- This interlayer's effect on debonding is not fully understood.
Purpose of the Study:
- To evaluate the impact of a resin interlayer on ceramic bracket debonding.
- To compare bracket failure, remnant adhesive, and enamel damage across bonding techniques.
- To analyze debonding mechanisms influenced by the interlayer.
Main Methods:
- 90 bovine teeth were bonded with ceramic brackets using direct, indirect (modified Thomas), or thermal-cured indirect methods.
- Each bonding group was subjected to lift-off, delamination, or twisting debonding techniques.
- Bracket failure (BF), adhesive remnant index (ARI), and enamel damage were assessed.
Main Results:
- Indirect bonding techniques (modified Thomas and thermal-cured) showed significantly lower BF and ARI scores compared to direct bonding.
- Debonding occurred at the filled-unfilled resin interface or within the interlayer for indirect techniques.
- Directly bonded brackets exhibited higher failure and remnant adhesive rates.
Conclusions:
- The resin interlayer formed during indirect bonding facilitates controlled debonding.
- Indirect bonding techniques offer a safer alternative for ceramic bracket removal, minimizing enamel damage.
- Understanding the debonding interface is crucial for improving orthodontic bracket systems.