What are the benefits of using self-adhesive resin cement instead of resin cements that require separate bonding agent and primer?

Self-adhesive resin cements contain an acid primer and an adhesive in the cement. Therefore, there is no need to etch or use a separate bonding agent and primer in order to obtain a bond. The lack of a separate etching gel and bonding agent often allows for metal-based and ceramic restorations to be bonded without the use of anesthetic. Self-adhesive cements (3M ESPE RelyX Unicem 2 Automix Self-Adhesive Resin Cement, 3M ESPE) have also been shown to have a lower incidence of sensitivity versus adhesive resin or total-etch esthetic resin cements. However, bond strengths are generally not as high as resin cements with separate primers.