ABSTRACT
Acidic primer is the bonding agent which combines the conditioning and priming agent into the single solution and was originally developed for the dentin bonding system. It is less harmful to the tooth structure and more convenient to manipulate than the traditional etching procedure. The purpose of this study is to evaluate the shear bond strength of various bonding materials when the enamel is treated with acidic primer for the bracket bonding procedure. Fifty recently extracted human premolars were randomly separated into five groups : Group I using Clearfil Liner Bond 2 adhesive system to the enamel treated with acidic primer, Group II using Transbond XT adhesive system to the enamel treated with acidic primer, Group III using panavia 21 adhesive system to the enamel treated with acidic primer, Group IV using Fuji-Ortho LC adhesive system to the enamel treated with acidic primer, Group V using Transbond XT adhesive system to the enamel treated with 37% phosphoric acid. The shear bond strength was measured with Instron universal testing machine after storing in 37oC water bath for 48 hours. After debonding, the teeth and brackets were examined under scanning electron microscope (SEM) and assessed with the adhesive remnant index (ARI). The results were as follows : 1. There were no significant differences in shear bond strength between group III (8.69 +/- 2.72 MPa), group IV (9.7 +/- 3.16 MPa), and group V (10.48 +/- 2.60 Mpa) (p>0.05). 2. The shear bond strength of group III and group IV was significantly higher than that of group I (1.09 +/- 0.53 Mpa), and Group II (2.70 +/- 1.46Mpa) (p0.05). This result suggests that the combination of acidic primer and some bonding adhesive can provide sufficient shear bond strength for clinical orthodontics.