Most Universal adhesives contain an adhesion promoting monomer that will bond to the tooth structure in both self-and total-etch modes. Universal bonding agents also contain water that will ionize the adhesion promoting monomer, which will alter the smear layer and incorporate it into the bonding layer without the need for etching with phosphoric acid when using it in the self-etch mode. With the total-etch technique, the smear layer is removed, and then the universal adhesive can penetrate the collagen fiber layer and hybridize the dentin. Universal bonding agents provide versatility when it comes to clinical applications, regardless of the bonding technique.