Shear-peel Bond Strengths of Hydrophilic Orthodontic Bonding Systems at 24 Hours

Objectives: This study evaluated and compared the shear-peel bond strengths of 3 orthodontic bonding systems: (Gp.1) a light-cured, 1 paste system which served as the experimental control (ie: dry bonding to etched enamel); (Gp.2) a cyanoacrylate moist orthodontic bonding system ;and (Gp.3) a light cured glass-ionomer moist orthodontic bonding system.

Methods: Thirty, recently extracted sound human teeth were mounted in the tooth cups of the Bencor Multi T test system (Danville Engineering, USA) and divided into 3 equal groups. The enamel was cleaned with a pumice and water slurry and etched with phosphoric acid according to the manufacturers’ recommendations. Bondable orthodontic buttons (Ormco, USA) were bonded to the etched enamel surfaces according the manufacturers’ guidelines and then stored in distilled water for 24 hours. The test assemblies were individually tested to failure in a Zwick Z010 testing machine (Ulm, Germany) with a crosshead speed of 0.5 mm/min and a 10 kN load cell. Bond strengths were computer generated and statistically analyzed using the Anova single factor test. The fractured interfaces were assessed under a traveling light microscope (Meiji, Japan) at 30X magnification.

Results: System1(Ormco,USA)(Gp.1) produced the highest mean bond strength values (21.32 ±5.1 MPa), followed by Fuji Ortho LC(Fuji,Japan)(Gp.3)(17.67 ±3.34 MPa) and Smartbond(Gestenco,Sweden)(Gp.2) (16.89 ±1.88 MPa). At the 5% level of confidence, no statistically significant differences were evident between any of the three materials (p>0.05; p=0.062004). Mixed adhesive-cohesive fractures occurred for all three systems.

Conclusions: The two moist bonding systems produced bond strengths in a similar range of magnitude to the control material indicating that moist or wet bonding could be a viable option in clinical orthodontics.