Shear bond strength comparison of RelyX Unicem with six other orthodontic resin adhesive systems

Orthodontic bracket adhesion involves multistep procedures which are technique sensitive to various factors within the oral environment. RelyX Unicem is a restorative/prosthodontic adhesive material which by virtue of its one step adhesion procedure may prove to be suitable for efficient orthodontic bonding. The objective of this study was to compare the SBS of RelyX Unicem with six other known orthodontic bonding materials. Seventy extracted human premolar teeth were divided into seven groups of 10 teeth each. On each group, metal orthodontic brackets were bonded using one of the seven bonding materials: (A) Transbond XT primer and Transbond XT luting cement (B) F2000 compomer primer/adhesive (C) Transbond Plus and Transbond XT luting cement (D) RelyX Unicem (E) Prime & Bond NT and Calibra cement (F) Xeno III and Calibra cement (G) NRC + Prime & Bond NT and Calibra cement. Shear bond strength evaluation of each tooth was tested and recorded using the Instron materials testing machine. The results show that the mean SBS for RelyX Unicem is 5.38 MPa and NRC is 4.70 MPa which rates weak compared to all the other materials where the means for the SBS are within the acceptable range of 5.9 to 7.8 MPa. It appears that by reducing the number steps followed for orthodontic bracket adhesion, the SBS of the orthodontic adhesive materials becomes significantly compromised to the extent where such materials can be rejected as suitable for orthodontic bracket adhesion. RelyX Unicem and NRC were found to be unsuitable for orthodontic bracket adhesion.