Adhesion of orthodontic cements to human enamel.

The tensile bonding characteristics of five orthodontic cements to etched human enamel with and without a silane primer after storage for 1, 7, and 30 days in artificial saliva at 37 C were compared. The scatter of the data was probably due to the wide variation of surface morphology of etched human enamel. Cement L, a composite resin cement, was significantly stronger than the other cements tested. Cement D, a polycarboxylate cement, was significantly the weakest cement tested. Cements U, O, and N-B were of relatively equal bond strengths. Of the direct-bonding systems commercially available, the N-B system had the fastest setting time. The silane primer used in the research decreased the bond strength of cement O; however, it significantly increased the bond strength of cement L. Storage in artificial saliva at 37 C for 30 days decreased the mean bond strengths of most of the orthodontic cements with and without a silane primer. The exceptions were cement N-B without a silane primer and cements O and D with silane primer.