Adhesives vs. resin cement

I have been using PermaCem without primer/adhesive as per the manufacturer`s instructions. I learned in a hands-on course that PermaCem was a good "Fleck`s" substitute for PFMs. Should I use Fleck`s from now on?

Michael Miller, DDS

I have been using PermaCem without primer/adhesive as per the manufacturer`s instructions. I learned in a hands-on course that PermaCem was a good "Fleck`s" substitute for PFMs. Should I use Fleck`s from now on?

Since Fleck`s is a zinc phosphate, PermaCem would be a good substitute for all metal-based restorations. However, the manufacturer, Zenith/DMG, does recommend using an adhesive for optimal performance. For metal-free restorations, such as In-Ceram or Procera, it is best to use Panavia 21. For all others, it is best to use any dual-cure resin cement.

How do you treat the inside of an In-Ceram crown before cementing it with Panavia 21? Do you etch? Sandblast? Silanate?

In-Ceram should be sandblasted with Rocatec, an adhesion-promoter from ESPE. If your lab does not have a unit, it should be aggressively sandblasted with 110-micron aluminum oxide. Then, you should cement with Panavia 21, no silane, and no adhesive in the crown. Even though we have not tested this protocol, it has been tested by others and seems to work. Make sure you use the ED primers on the preparation.

I currently am using Panavia for bonding gold inlays, onlays, and crowns with compromised resistance and retention form. I am interested in 3M`s product, RelyX ARC. The old 3M resin cement did not cure well without light-curing. Has this been corrected?

RelyX ARC is a much better product than the old Scotchbond Resin Cement. In our June issue of Reality Now, we reported that RelyX ARC would chemically set rock hard in 8.5 minutes extraorally. So, it will definitely work with gold should you choose to use it. However, it still is a good idea to light-cure through the tooth and at the margins to accelerate the set.

What is the best technique for adding composite to a fully cured composite (no air-inhibition layer)? For example, what if you discover an air bubble in a composite restoration as you are polishing or you just need to add more composite?

If the composite to which you are adding was just cured (i.e., at the same appointment), all you need to do is lightly roughen it with a diamond just to clean off any polishing debris (you also could sandblast it, if you prefer). Then, rinse, dry, apply etch for five seconds as an extra decontamination step, rinse, dry, apply unfilled resin (such as Heliobond), lightly air-thin, and add the composite. If you are repairing a previously cured composite (i.e., it has been in the mouth for some time) and it is just the composite (no tooth structure involved), sandblast the composite with Co-Jet, which is a silica-based adhesion-promoter from ESPE. After using Co-Jet, blow off the residue (do not rinse), apply silane, dry, apply unfilled resin, lightly air-thin, and add the composite.

When you use a dual-cure adhesive, can you cure it right away or should you let it sit for a time? (Will it interfere with the polymerization process?) If you do not cure it, will it completely set on its own? If you have to wait, why bother using a light at all?

This depends on the film thickness. With Prime & Bond NT Dual Cure, your bond strength is much higher when you light-cure it before seating your restoration. With OptiBond (original formula), you cure it after seating your restoration. If you cure OptiBond before seating your restoration, its film thickness may prevent complete seating, while the film thickness of Prime & Bond Dual Cure is only about five microns, allowing you to seat any type of restoration.

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.reality=esthetics.com.

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