Are the low-shrinking composites suitable for orthodontic bracket bonding?

Area of Science:

• Orthodontics
• Dental Materials Science

Background:

• Orthodontic bracket bonding relies on composite adhesives.
• Minimizing polymerization shrinkage is crucial for adhesive longevity.
• Evaluating new low-shrinking composites is essential for clinical practice.

Purpose of the Study:

• To compare the shear bond strength (SBS), adhesive remnant index (ARI), and microleakage of a low-shrinking composite versus a conventional composite for orthodontic bracket bonding.

Main Methods:

• Human premolars were bonded with either Silorane (low-shrinking) or Transbond-XT (conventional) composite.
• Shear bond strength was measured using a universal testing machine.
• Adhesive remnant index and microleakage were assessed using dye penetration and failure analysis.

Main Results:

• Conventional Transbond-XT demonstrated significantly higher SBS than the low-shrinking composite.
• Significant differences in ARI scores favored the conventional composite.
• The low-shrinking composite exhibited significantly lower microleakage compared to the conventional composite.

Conclusions:

• While the low-shrinking composite offers reduced microleakage, its SBS and ARI scores were insufficient for orthodontic bracket bonding.
• Further development may be needed to improve the mechanical properties of low-shrinking composites for this application.