Comparison of shear, tensile and shear/tensile combined bonding strengths in bracket base configurations

Lee, Choon Bong; Lee, Seoun Ho; Kim, Jong Ghee

Abstract

The purpose of this study was to evaluate shear, tensile and shear/tensile combined bond strengths(SBS, TBS, S/TBS) in various orthodontic brackets bonded to human teeth with chemically cured adhesive (Ortho-one, Bisco, USA). Five types of metal brackets with various bracket base configurations (Micro-Loc base(Tomy, Japan), Chessboard base(Daesung, Korea), Non-etched Foil Mesh base(Dentarum, Germany), Micro-Etched foil Mesh base(Ortho Organiners, USA). Integral base(Unitek, USA)) were used in this study. Shear, tensile and shear/tensile combined bond strengths according to the direction of force were measured by universal testing machine. The bracket base surface after bond strength test were examined by stereoscope and scanning electron microscope. The assessment of remnant on bracket base surface was carried out by ARI(adhesive remnant index). The results obtained were summarized as follows ; 1. In all brackets, SBS was in the greatest value(p<0.05), TBS was in 50% level and S/TBS was in 30% level of SBS. 2. In bond strength, Micro-Loc base bracket showed the maximum bond strength(SBS:22.68+/-1.37kgf, TBS:11.37+/-0.42kgf, S/TBS:6.69+/-0.34kgf) and Integral base bracket showed the minimum bond strength(SBS:10.52+/-1.27kgf, TBS:4.27+/-1.08kgf, S/TBS:2.29+/-0.58kgf) (p<0.05). 3. In bond strength per unit area Integral base bracket showed the minimum value, Micro-Loc base and Chessboard base brackets were in similar value(p>0.05). Non-Etched Foil Mesh base and Micro-Etched Foil Mesh base bracket were similar in SBS and TBS(p>0.05), But Micro-Etched Foil Mesh base bracket was greater than Non-Etched Foil Mesh base bracket in S/TBS(p<0.05). 4. Bond failure sites were mainly between bracket base and adhesive, therefore ARI scores were low.