Does surface priming increase the bond strength of orthodontic brackets? An experimental study

Area of Science:

• Dental Materials Science
• Orthodontic Adhesion
• Biomaterials

Background:

• Orthodontic bracket debonding can damage tooth enamel and provisional restorations.
• Improving shear bond strength (SBS) is crucial for predictable orthodontic treatment outcomes.
• Metal primer II (MP II) is a bonding agent used in dentistry.

Purpose of the Study:

• To evaluate the effect of MP II on the SBS of orthodontic brackets bonded to human teeth.
• To assess the impact of MP II on the SBS of orthodontic brackets bonded to bis-acryl composite provisional material (Bis-Acryl).

Main Methods:

• Extracted human premolars and bis-acryl composite specimens were prepared.
• Specimens were divided into groups with and without MP II application before bracket bonding using Transbond XT.
• Shear bond strength was tested, and failure modes were analyzed using the Adhesive Remnant Index (ARI).

Main Results:

• MP II significantly increased SBS on both human teeth (T) and provisional materials (PM) compared to controls (p < .001).
• Bond strength was consistently higher for provisional materials than for teeth, both with and without MP II (p < .001).
• Tooth groups showed predominantly adhesive failure, while provisional material groups shifted from cohesive to adhesive failure after MP II application.

Conclusions:

• MP II application effectively enhances the shear bond strength of orthodontic brackets on human enamel.
• MP II also improves the bond strength of brackets bonded to bis-acryl composite provisional materials.
• The use of MP II offers a promising method for strengthening bracket adhesion in diverse dental substrates.