Shear Bond Strength of Ceramic Brackets with Different Base Designs: Comparative In-vitro Study

Area of Science:

• Orthodontics
• Dental Materials Science
• Biomaterials Engineering

Background:

• Understanding the shear bond strength (SBS) of ceramic brackets is crucial for successful orthodontic treatment.
• Bracket base design significantly influences the bond strength to enamel.

Purpose of the Study:

• To compare the shear bond strength (SBS) of ceramic brackets with varying base designs.
• To analyze the fracture site after debonding to assess bond failure patterns.

Main Methods:

• Five bracket types (four ceramic, one metal) with distinct base designs were evaluated.
• Brackets were bonded to 50 maxillary premolars using Transbond XT adhesive.
• Shear bond strength was tested using a universal testing machine, and failure modes were analyzed using the Adhesive Remnant Index (ARI).

Main Results:

• The microcrystalline base demonstrated the highest mean SBS (27.26±1.73 MPa).
• The bead ball base (23.45±5.09 MPa), adhesive precoated base (20.13±5.20 MPa), polymer mesh base (17.54±1.91 MPa), and mechanical mesh base (17.50±2.41 MPa) showed progressively lower SBS.
• Significantly different ARI scores were observed among the groups (p<0.001).

Conclusions:

• Bracket base design is a significant factor affecting the shear bond strength (SBS) of ceramic and metal brackets.
• All evaluated bracket base designs achieved clinically acceptable bond strength to enamel.