The components of fourth generation dentin bonding systems are described as
As in the fourth-generation adhesives, enamel and dentin are etched simultaneously; these systems were initially called the “total-etch” technique, now they are commonly known as the “three-step etch-and-rinse” technique.
Ref : Talal A, Nasim HM, Khan AS. Enamel etching and dental adhesives. InAdvanced Dental Biomaterials 2019 Jan 1 (pp. 229-253). Woodhead Publishing
Self etching adhesive
Self etching primer/adhesive
Total etch, multi bottle
Total etch, single bottle