The advantage of self-etching systems is that the smear layer is altered but never removed, resulting in a reported lessening of post-operative sensitivity and simplification of protocol. The adhesive acts as both an etchant and a primer. This implies that etching and priming occur to the same depth of penetration. Before applying the self-etching primer, the preparation is dried. This means that there is no guessing as to “how wet is wet” as with traditional, total-etch adhesives.