Shear bond strength comparison between direct and indirect bonded orthodontic brackets

Area of Science:

• Orthodontics
• Biomaterials Science
• Dental Adhesives

Background:

• Orthodontic bracket bonding is crucial for treatment efficacy.
• Direct and indirect bonding techniques are commonly used.
• Evaluating adhesive strength is essential for clinical success.

Purpose of the Study:

• To compare the shear bond strength of orthodontic brackets using indirect bonding with a new adhesive versus direct bonding with a light-activated adhesive.
• To assess the amount of residual adhesive after debonding for both techniques.

Main Methods:

• Fifty-four extracted premolars were randomly assigned to either indirect or direct bonding groups (n=27 each).
• Shear bond strength was measured using a universal testing machine at a crosshead speed of 1 mm/minute.
• Adhesive remnants were quantified using a modified adhesive remnant index under magnification.

Main Results:

• Mean shear bond strength was 11.2 MPa for indirect bonding and 10.9 MPa for direct bonding.
• Both groups demonstrated bond strengths above the clinically recommended range (5.9–7.8 MPa).
• No statistically significant difference in shear bond strength or adhesive remnant scores was found between the two techniques.

Conclusions:

• Both direct and indirect bonding techniques provide comparable and clinically adequate shear bond strength for orthodontic brackets.
• The choice between direct and indirect bonding may not significantly impact initial bond strength or adhesive remnant levels.
• Further research could explore long-term bond durability and patient-reported outcomes.