Bonding with self-etching primers--pumice or pre-etch? An in vitro study

Area of Science:

• Orthodontics
• Dental Materials Science
• Adhesive Dentistry

Background:

• Effective bonding of orthodontic brackets is crucial for successful treatment outcomes.
• Self-etching primers (SEPs) offer an alternative to traditional acid-etching techniques.
• Enamel surface preparation methods can influence the bond strength of orthodontic adhesives.

Purpose of the Study:

• To compare the shear bond strengths (SBSs) of orthodontic brackets bonded with SEPs.
• To evaluate the impact of different enamel surface preparations on SBS.
• To assess the adhesive remnant index (ARI) following bracket debonding.

Main Methods:

• A two-by-two factorial design was employed with sixty human premolars.
• Four enamel preparation groups were established: pumicing plus pre-etching, pumicing only, pre-etching only, and no preparation.
• Shear bond strength (SBS) and adhesive remnant index (ARI) were measured after 24-hour water storage.

Main Results:

• The group pre-etched with 37% phosphoric acid for 5 seconds demonstrated the highest SBS (36.2 ± 8.2 MPa).
• Pumicing alone resulted in lower SBS (16.1 ± 7.3 MPa), while no preparation yielded the lowest SBS (13.1 ± 10.1 MPa).
• The combination of pumicing and pre-etching yielded an SBS of 22.9 ± 6.6 MPa.
• ARI scores indicated that most adhesive remained on the bracket across all groups.

Conclusions:

• Pre-etching enamel surfaces with 37% phosphoric acid for 5 seconds is a superior method compared to pumicing when using SEPs for bonding orthodontic brackets.
• This preparation technique significantly increases shear bond strength, optimizing bracket adhesion.
• The findings suggest that incorporating a brief phosphoric acid pre-etch enhances the efficacy of SEPs in orthodontic bonding.