Often times I throw around terminology that may be confusing to those reading from different schools or countries. In a recent entry, I mentioned bonding systems and used the terminology of “4th generation.” Some of us may take for granted our understanding of this, so I thought I might recap bonding agents over a few articles in order to increase our knowledge of the subject.
Dental literature and manufacturers use the terminology of generations when describing bonding agents. While somewhat confusing, there seems to be little movement amongst the industry to move away from generational classification of bonding agents.
Today I will discuss 1st thru 3rd generation bonding agents. They are of little importance to us today, as 4th generation and above are the only generations currently available on the market.
1st generation bonding agents- Date back to early 50’s; achieved dentin bond strengths of 2-3 MPa that were unstable in water; Cervident by SS White was the first commercially sold dentin bonding agent “theoretically bonding to enamel and dentin by chelation with calcium on the tooth surface and had improved water resistance.” Obviously, a dentin bond that is unstable in water is no good intraorally. I think it is interesting to note that dentin bonding was being explored as far back as the 1950’s.
2nd generation- introduced in 1978; relied mainly on enhancing ionic interactions within the dentin structure; yielded bond strengths of 5-6 MPa; clinical trials yielded poor results; most bond strength probably came from bonding to the smear layer and not to the dentin itself.
3rd Generation- developed in early 1980’s; first bonding agents that utilized the philosophy of acid etching dentin to remove smear layer; served as basis for some bonding systems available today like Amalgambond and C&B Metabond; adhesives were mainly self-curing resins; Scotchbond 2 was first product to receive provisional acceptance from ADA which was followed by full acceptance.
There we have it. A brief look at 1st thru 3rd generation bonding agents. I will be back soon with a summary of 4th thru 7th generation bonding agents.
Always remember, the generational classifications pertain to dentin bonding only. Enamel bonding has been successful for many years with an acid etch technique. Dentin bonding requires the presence of adhesives and primers. Just an afterthought worth noting…