Different Composite Veneer Surface Preparations for Metal Orthodontic Bracket Bonding: An In Vitro Study

Area of Science:

• Dental Materials Science
• Orthodontic Adhesion
• Composite Resin Technology

Background:

• Assessing shear bond strength (SBS) is crucial for orthodontic bracket adhesion to composite veneers.
• Different surface preparation techniques can influence the mechanical properties of the bond interface.

Purpose of the Study:

• To evaluate the shear bond strength (SBS) of orthodontic metal brackets bonded to composite veneers.
• To compare the effects of various surface preparation methods, etching agents, adhesive protocols, and bonding agents on bond strength.

Main Methods:

• One hundred composite disks were divided into 10 groups with varying surface preparations (roughening/no roughening), etching agents (phosphoric/hydrofluoric acid), adhesive protocols (self-etch/total-etch), and bonding agents (with/without G-Premio Bond).
• Metal brackets were bonded using Transbond XT resin, followed by incubation, thermocycling, and SBS testing via a universal testing machine.
• Adhesive Remnant Index (ARI) was used to analyze failure modes.

Main Results:

• Surface roughening and preparation materials significantly affected bond strength (p < 0.0001).
• No significant difference in bond strength was found between phosphoric and hydrofluoric acid etching (p > 0.05).
• The highest SBS was observed with roughening + total-etch + phosphoric acid + G-Premio Bond (10.24 ± 2.99 MPa), while the lowest was without roughening + phosphoric acid (1.47 ± 1.06 MPa).

Conclusions:

• Surface preparation significantly influences the shear bond strength of metal brackets to composite veneers.
• High bond strength achieved with G-Premio Bond and specific surface preparations (ARI score 4) may risk veneer damage during debonding.
• Surface preparation methods yielding lower bond strength are recommended unless frequent bracket failures occur.