Comparison of Bond Strength of Different Eighth-Generation Adhesives in Orthodontic Bonding

This in vitro study aims to compare the shear bond strength (SBS) and Adhesive Remnant Index (ARI) values of various eighth-generation adhesives used in orthodontic bonding.

A total of 40 extracted human premolars were randomly divided into four groups; (i) Group 1: 3M Unitek Transbond-XT (fifth-generation adhesive, conventional etch, 3M Electro & Communication India Private Limited, Bengaluru, India) (ii) Group 2: 3M ESPE Single Bond Universal (eighth-generation, 3M Electro & Communication India Private Limited, Bengaluru, India), (iii) Group 3: Tetric-N-Bond Universal (eighth-generation, Ivoclar Vivadent, Schaan, Liechtenstein), and (iv) Group 4: G-Premio Bond (eighth-generation, GC Corporation, London, UK). The premolars, stored in saline water, were bonded with stainless steel brackets using respective bonding agents and 3M Unitek Transbond-XT composite. The SBS values were tested using an Instron universal testing machine (Asian Test Equipments, Ghaziabad, India). Post-debonding, ARI scores for each group were evaluated using a stereomicroscope at 10X magnification.

The SBS values for the adhesives were 3M ESPE Single Bond Universal (2.29 ± 1.12 MPa), Tetric-N-Bond Universal (5.26 ± 2.6 MPa), G-Premio Bond (5.07 ± 1.72 MPa), and 3M Unitek Transbond-XT (10.22 ± 4.83 MPa). ARI scores differed across groups, with most samples showing a score of 2 and only the 3M Unitek Transbond-XT group recording an ARI score of 3. The Chi-square value was 19.42 (p = 0.02), indicating a moderately significant difference.

This study concluded that while eighth-generation adhesives like Tetric-N-Bond Universal and G-Premio Bond offer advantages in enamel protection and cleanup due to lower ARI scores, their SBS was lower than that of 3M Unitek Transbond-XT, which performed significantly better.