Ask the Experts Answer

What is the difference between the bonding generations?

• 4th generation adhesives are 3-step adhesive systems, involving etching, priming, and application of a bonding resin in three separate steps.
• 5th generation adhesives are 2-step adhesive systems, either involving etching followed by application of a combined primer-bonding resin or involving application of a combined etch-primer (self-etching primer) followed by a bonding resin.
• 6th/7th generation adhesives are 1(single)-step adhesive systems, involving application of etchant, primer, and bonding resin to the preparation all in a single step.
• Classifying dental adhesives by generations can be confusing and ambiguous. A more logical and straightforward approach would be to classify adhesives by the number of clinical steps involved and/or by the etching method (total-etch or self-etch).