Michael Miller, DDS
The Clinical Research Associates Newsletter gave very poor shear bonding strengths for Prime and Bond NT with self-cure activator. Does your research agree? Have you ever tested the shear bonding strength using Encore build up by Centrix?
Another reader wrote: CRA showed bond strengths with dual and self-cure composites. I`m using more light-cure buildup material now and wonder whether there are comparable weak bonds, such as with Prompt L-Pop from ESPE with light cure. I guess I`ll stick with Clearfill SE bond and various buildup materials. I know we`re not supposed to use etch before using SE Bond. Is the same true for the ESPE product? They even recommended it before sealing teeth.
As you probably know, our report three years ago on the incompatibility of single-component adhesives and self-cure composites was the first on this subject. At that time, we investigated all of our REALITY`S CHOICES single-component adhesives and found the only one that would bond to self-cure composite was One-Step from Bisco. Shortly after our report, the self-cure activator was added to Prime & Bond NT. Our test materials were Core Paste from Den-Mat and Bisfil 2B from Bisco. We have not tested Encore, but it should behave very similarly to Core Paste. There has never been any problem with bonding to light-cured materials.
We first published our data in the 1999 edition of our book. Our results were much different than those of CRA. After the test specimens were allowed to cure in a temperature/humidity chamber set at 37°C/95 percent humidity for five minutes to simulate a core being placed clinically, bond strengths were 15.2MPa for Bisfil 2B and 14.5MPa for Core Paste. While that was lower than the bond strength to light-cured composite (19.7MPa), it should be more than adequate for a core and will no doubt increase over time.
Therefore, we believe CRA`s results with Prime & Bond NT Dual Cure are incorrect, since our tests and our clinical experience clearly show it does bond to at least two self-cure materials.
As far as Prompt L-Pop is concerned, it is only designed for light-cured composites and compomers, such as Clearfil SE Bond. CRA found Prompt had no bond strength to any of the self-cure materials, but that SE Bond did actually adhere to all of its tested products. Our results for both products revealed that neither bonded to Core Paste or Bisfil 2B. Our tests are consistent with those of the respective manufacturers. We do not recommend either product when using a self-cure core material. And you should not etch with phosphoric acid when using Prompt or SE Bond.
I have had problems with Empress onlays or crowns coming off using the Variolink system with Heliobond. The material always sticks to the crown and there is no bond to the tooth.
Another reader wrote: I use the Variolink and Heliobond with the two-component Syntac system. Do I also need Excite? I was at an occlusion seminar where the speaker stated this type of restoration was nothing more than a long-term temporary. Is this true?
Heliobond is merely an unfilled resin and has no adhesion to dentin. You must use a dental adhesive on the tooth. Please see our section on Dental Adhesives in the 2000 edition of REALITY. If you want to stay with Ivoclar, the correct adhesive would be Excite. If you are using the original Syntac, then you don`t have to use Excite. However, for dual cure applications, your better choice would be Prime & Bond NT Dual Cure.
As far as Empress being a long-term temporary, that`s nonsense. Assuming the restoration is well done and the occlusion is properly adjusted and any adjusted surface is properly repolished, an Empress restoration should have excellent longevity, maybe even for the patient`s lifetime.
Dr. Miller is the publisher of REALITY and REALITY Now, the information source for esthetic dentistry. He is an international lecturer and a fellow of the American Academy of Cosmetic Dentistry, as well as a founding member. He maintains a private practice in Houston, Texas. For more information on REALITY and to receive a complimentary issue of his monthly update, REALITY Now, call (800) 544-4999 or visit www.realityesthetics.com.