Shear Bond Strength of Different Adhesive Systems for Bonding Orthodontic Brackets to Porcelain Surfaces

ABSTRACT

The aims of this study were to measure and compare the effects of five different adhesive systems on the shear bond strength of orthodontic brackets bonded to porcelain surfaces and to analyze the modes of bond failure after de-bonding the brackets. One hundred porcelain cylindrical disks were divided into five groups. The orthodontic brackets were bonded to the porcelain using five different adhesive systems Group I, etching with 9.6% hydrofluoric acid; Groups II and IV, etching with 37% phosphoric acid followed by Silane; Groups III and V, etching with 9.6% hydrofluoric acid followed by silane. Specimens in Groups I, II and III were bonded with System1™ + and those in Groups IV and V with Super-Bond C\&B. The shear bond strength was then tested using a universal testing machine. The mean shear bond strength values in Groups I to V were 10.9, 18.5, 20.7, 23.7 and 27.6 MPa, respectively.  All data were analyzed using an analysis of variance. The lowest mean shear bond strength was in Group I and was significantly different (p \< 0.05) from that in the other groups. There was no significant difference between the mean shear bond strength values in Groups II, III and IV (p \< 0.05). Group V had the highest mean shear bond strength and was significantly different from that in Groups I, II and III (p\< 0.05). The porcelain/adhesive interface was the commonest site of failure in Group I (65%), whereas the failure sites in the other groups showed mixed types of bond failure with no specific location predominating. Some damaged porcelain surfaces were found in Groups II, III, IV and V. Keywords shear bond strength, adhesive systems, dental porcelain, orthodontic bracket