In an effort to help the dental practitioner better understand the sometimes complicated terminology relating to dental adhesives, Dentalcompare was lucky enough to be able to ask educator and clinician Dr. Jose Luis Ruiz a few basic questions. We hope this sheds some light on the subject.
Dentalcompare: There appears to be confusion among dentists about terminology surrounding dental bonding systems. Just as an introduction, please define self-etch bonding and total-etch bonding, outlining the important differences and particular applications for each.
Dr. Ruiz: Terminology of dental adhesives had historically been very confusing, especially with the "generation" nomenclature, or even the component-based nomenclature.
When it comes to adhesive bonding systems, there only 2 families–the self-etch and the total-etch. Simply…Total etch requires a separate phosphoric acid step to etch the enamel and dentin, a subsequent rinse, and application of primer and bond. Self-etch systems have an acidic resin which etches and primes without the need for etching or rinsing, and then there will be a subsequent application of bond.
Newer generations of both families have attempted to simplify the process by putting both primer and bond in one bottle, in some cases this oversimplification has resulted in less then ideal results. I am personally partial to 2-bottle systems.
In regards to when to use one or the other, the literature shows that, properly used, both systems can work. Self-etch systems are without a doubt more user friendly, which translates in to more predictable results. I personally use primarily self-etch systems because I know that the dentin adhesion with a good quality self-etch bonding system, like Kuraray’s Protect Bond, is as good as it can possibly be, and when I am working with mostly enamel or even uncut enamel, I will do a separate enamel etching with phosphoric acid for 15 seconds to achieve maximum adhesion to enamel, this way I only need to have one light-cure, self etch system for direct restorations and one dual-cure, self-etch system for indirect.
DC: Dentalcompare conducted a casual Web poll asking practitioners about when they use self-etch or total-etch systems. Here are some responses:
- “It depends on how much enamel and dentin are available for bonding…if little dentin use total-etch, if little enamel use self-etch.”
- “Self-etch for composites, still total-etch for veneers.”
- “I'm using self-etch for all direct restorations and some indirects (i.e. inlays/onlays). For some reason, I'm still hesitant to commit 100% to self-etch for indirect veneer/crown cementation and am still using total-etch techniques for those (although I have recently done several cases with self-etch for evaluation).”
Do these comments reflect a high-level of knowledge about the difference between self- and total-etch systems?
Dr. R: Somewhat. It looks like these comments come from people friendly to self-etch, because many educators only like total-etch for everything. Nevertheless the comments reflect the fact that people trust the results and like the benefits of self-etch on dentin. It also reflect the belief that self-etch doesn’t work as well on enamel. I trust enamel adhesion with self-etch as long as the enamel has been cut. On the other hand, I am convinced based on my own research that with a short phosphoric acid etching, the adhesion to enamel, especially uncut, increases to the point of being just as good as it would be with a regular total-etch system. So if we understand this, we don’t need two systems. We can use only one system, a self-etch for everything.
DC: Discuss the sensitivity issue? Better with self-etch?
Dr. R: Post-operative sensitivity is a touchy subject. Many people in academia will strongly oppose to the idea that total-etch systems cause more sensitivity. But CRA’s surveys and my own conversation with hundreds of dentists during my lectures all over the country have convinced me that post-op sensitivity with total-etch is a problem which many dentists have to deal with on a daily basis.
First of all let me start by saying that the belief that it is normal for patient to be sensitive for days and weeks after an adhesive procedure, like a direct composite or an indirect porcelain onlay, is absolutely false. Properly performed adhesive procedures will almost always result in zero post-op sensitivity from day one, very different than with amalgam. Self-etch bonding systems are much more user friendly, and they don’t require the acidic removal of the smear layer. This leads to more predictability and less post-operative sensitivity.
DC: Discuss the bond strength issue between self- and total-etch.
Dr. R: When using a good quality self-etch system like Kuraray’s SE Bond or Protect Bond, the bond strength will be as high and predictable as any system can provide, and literature is clear about this. Enamel is a different issue. When bonding to cut enamel, self-etch systems do an acceptable job, some better that others, but if we want higher strength or we are bonding to uncut enamel, it makes sense to do a short phosphoric acid etching and then use the self-etch. Then we have the best of both worlds.
DC: Are manufacturers doing an adequate job of educating dentist customers about bonding/adhesive systems?
Dr. R: My feeling is that manufacturers are usually not doing enough to educate the dental community about bonding systems. On the other hand, academics and educators in general are not doing that great of a job either, especially with all the bickering and contradictory information being put out there. Additionally, I feel that sometimes manufacturers in an effort to look good, compete and gain market share, sometimes bring materials in to the market which are not always as good as the predecessors, further confusing dentists. This can’t be good for the profession.