What are the advantages and disadvantages, and the primary difference in usage among acetone, ethanol, and water-based solvents in dental bonding agents?

The main differences in the water and acetone/ethanol systems are that water-based systems are primarily the self-etching adhesives (6^th– and 7^th-generations). These bonding agents must be water based because they contain a mild acidic primer within the adhesive. The acetone- and ethanol-based systems are 4^th– and 5^th-generation systems, which are total-etch products. The etching of enamel and dentin comes in a separate step utilizing phosphoric acid, so they do not need a water solvent to deliver the dentin primer. They do have to be water soluble, however, for the hydrophilic primer to penetrate the relatively wet dentin. The primary difference in usage is that the water-based systems are not as technique sensitive and the tooth can be drier during usage. Acetone- and ethanol-based systems require a more moist bonding surface for them to work properly.