Bonding of ceramic brackets to enamel: morphologic and structural considerations.

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Materials

Background:

• Ceramic brackets are widely used in orthodontics due to their aesthetics.
• Understanding the interfacial properties of ceramic brackets is crucial for successful orthodontic treatment.
• Previous studies have focused on specific bracket types, necessitating a comparative analysis.

Purpose of the Study:

• To evaluate the form and microstructure of three ceramic bracket types.
• To assess interfacial surface shapes and bond strengths with different adhesives after thermocycling.
• To determine the optimal bonding mechanism for ceramic brackets.

Main Methods:

• Characterization of monocrystalline and polycrystalline ceramic bracket microstructures.
• Assessment of bonding base morphology and its implication on adhesive interaction.
• Evaluation of bond strength using visible light-cured and chemically cured adhesives.
• Thermocycling to simulate intraoral conditions and assess bond durability.

Main Results:

• Three distinct bonding mechanisms were identified: chemical bonding, mechanical retention with adhesion, and micromechanical retention with adhesion.
• The gamma-methacryloxypropyltrimethoxysilane coupling agent was applied to all ceramic bases.
• Bracket base design influenced the adhesive layer thickness.
• The highest bond strength was achieved with micromechanical retention and adhesion, with failure at the resin/bracket interface.

Conclusions:

• Ceramic bracket design significantly impacts bond strength and failure modes.
• Micromechanical retention combined with adhesion offers superior bond strength for ceramic brackets.
• Understanding interfacial characteristics is key to improving bracket-enamel adhesion in orthodontics.