The Effect of Universal Adhesives on Shear Bond Strength of Orthodontic Brackets

A proper bond between enamel and bracket is essential in orthodontic treatment. Recently, a new type of adhesive (universal adhesive) has been introduced, which has been claimed to present the ability to bond with metal surface. The aim of this study was to evaluate the effect of universal adhesives on shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets to enamel surfaces.

In this experimental in-vitro study, 56 intact human premolars were randomly divided into four groups according to the adhesives used. All teeth were etched by 37% phosphoric acid. Then, in Group 1 (control), Transbond XT primer was only applied on the enamel surface. Group 2: Transbond XT primer applied on both enamel and bracket base. Group 3: Single Bond Universal adhesive was applied on both enamel and bracket base. Group 4: G-Permio Bond was applied on both enamel and bracket base. Then, the brackets were bonded to teeth with Transbond XT composite. After storing samples in water for 24 hours and thermocycling (2000 cycles), SBS was recorded using a Universal Testing Machine. The debonded samples were examined under the stereomicroscope at 10x magnification to check the amount of remaining adhesives on teeth (ARI).

Group 3 showed the highest SBS (25.4±8.7 Mpa) and group 2 showed the lowest SBS (16±5.3 Mpa). The SBS of group 3 was significantly more than group 2 (p=0.03) and there was no significant difference between the other groups. There was no significant differences among the four groups in term of ARI score.

The bond strength values of orthodontic brackets to enamel using universal adhesives (Single Bond Universal and G-Permio Bond) are similar to the conventional adhesive (Transbond XT).