Objective: Self-etching primers are widely used in restorative dentistry. However, only one primer has been developed for orthodontic applications. The objective of this study was to assess the suitabiliy of restorative self-etching primers on unabraded enamel. Material and Methods: Seven self-etching primers (Transbond™ SEP +, Xeno®III, Clearfil™SE, Futurabond®NR, OneCoat, M-Bond and OptiBond®) were compared with two conventionally-etched control groups (Transbond™ MIP). All groups with the exception of one of the two control groups underwent thermo-cycling (1000x, 5-55°C). Bovine teeth stored in physiological saline solution were used for the purpose of this study. Results: Both before and after thermo-cycling, the control groups presented very similar shear strengths which did not differ significantly from each other or from the Transbond™ SEP + and Clearfil™SE specimens. During thermo-cycling, all groups except the control group and the Transbond™ SEP + specimens displayed losses from the shear bodies. These losses occurred on all of the OptiBond® samples. The adhesive remnant index (ARI) and enamel tear-outs correlated closely with the adhesive values. Conclusions: Our adhesive value assessments support the conclusion that only Transbond™ SEP + and Clearfil™SE can be recommended for clinical us
