Light cured direct bonding--is it necessary to use a primer?

Area of Science:

• Dental materials science
• Adhesive dentistry
• Biomaterials engineering

Background:

• Orthodontic bracket bonding relies on adhesive systems to secure brackets to enamel.
• Primer resins are often used to enhance the bond strength between the adhesive and the etched enamel surface.
• Understanding the influence of primer viscosity and composition is crucial for optimizing clinical outcomes.

Purpose of the Study:

• To evaluate the effect of a low viscosity unfilled primer resin on the shear bond strength of orthodontic bracket adhesives.
• To assess the bond strength at the enamel/adhesive and bracket/adhesive interfaces.
• To determine if the use of an unfilled primer significantly alters bond strength compared to its absence.

Main Methods:

• Orthodontic brackets were bonded to etched enamel using a standard adhesive system.
• One group received a low viscosity unfilled primer, while a control group did not.
• Shear bond strength was measured in megapascals (MPa) after debonding.
• Statistical analysis (P > 0.05) was performed to compare bond strengths between groups.

Main Results:

• No statistically significant differences were observed in shear bond strength between the primer group and the control group (P > 0.05).
• The bond strength at the enamel/adhesive interface was comparable in both conditions.
• The bond strength at the bracket/adhesive interface also showed no significant variation.

Conclusions:

• The use of a low viscosity unfilled primer resin does not significantly impact the shear bond strength of the bracket adhesive system to etched enamel.
• The primer does not appear to negatively or positively influence the integrity of the bonding system at critical interfaces.
• Clinicians can consider using such primers without expecting significant alterations in immediate bond strength performance.