Is light-curing necessary?

March 1, 2005
Ihave two unrelated questions. First, we recently obtained [Discus] Cabrio CQ adhesive and catalyst to use with PermaCem on gold-based restorations.

Ihave two unrelated questions. First, we recently obtained [Discus] Cabrio CQ adhesive and catalyst to use with PermaCem on gold-based restorations. According to Discus instructions, we mix the two parts, paint it on the preparation(s), and immediately (within one minute) place the restoration with PermaCem for 2.5 minutes with no air-thinning of the adhesive. Is this correct? Second, my favorite adhesive system for both directs and all-ceramic indirects for the past 10 years has been Optibond FL. Although more recent instructions indicate that it is not necessary to light-cure the Optibond primer, we always have for 10 seconds. We have a zero postoperative sensitivity rate and zero debonding rate. Could it be that by light-curing the primer, it toughens the hybrid layer so that application and blotting of the adhesive doesn’t collapse the collagen fibers on the dentin surface? I’ve always thought that there was camphorquinone in the primer for a reason, and I seem to recall that the original instructions called for light-curing the primer. Is it practical to test this protocol to see if there is a difference between cured and noncured primer?

First, forget Discus’ instructions and follow those in the 2005 Annual Edition. You have to apply air to evaporate the solvent. Setting time depends on the cement, not adhesive. CQ is mixed in a 1:1 ratio, not 2:1 as the original formula. Second, we have tested curing versus not curing the OptiBond FL Prime and found no differences whatsoever. As you stated, Kerr even stopped recommending curing the Prime. About the only advantage to curing the Prime is to allow it to stabilize the hybrid layer during the curing period. However, you could probably achieve the same benefit by merely allowing it to sit on the dentin for an additional 10 seconds before applying the FL Adhesive. Nevertheless, if you have had 100 percent success curing the Prime, we suggest continuing that protocol.

Den-Mat recommends using Infinity Syringeable without the need to etch and bond. Your evaluation in REALITY states that this should never be done. Why? Did you find inadequate bond strength or other adverse problems?

Actually, our tests reveal much higher bond strengths when the dentin is etched and an adhesive is applied, although the bond strengths without etch and bond are probably adequate for crowns with good resistance and retention form.

I have been suspicious of the output of our older 3M Elipar LED light. On the light base, it has a test port and series of lights that all light up when testing the light output. Our dental rep says that is how you test the adequacy of this LED light. However, when I tested it on the Demetron light meter, it only gave a reading of around 200 mw/cm2. I know that, with conventional halogen lights, you want a minimum of 400 mw/cm2. Does this 400 mw/cm2 minimum readout hold true for LED lights as well, or should we go by the particular light’s own testing method?

The original Elipar FreeLight has been discontinued and replaced with the more powerful Elipar FreeLight 2. Our test of the first version showed a peak power of 427 mw/cm2, while the new version puts out an impressive 904 mw/cm2. Your reading of 200 mw/cm2 seems quite low. Regardless of the built-in radiometer, a reading that low gives us cause for concern. We suggest sending it back to 3M for a check-up. Don’t use it clinically until this loss of power issue is resolved.

I have read all the reports on LED curing lights, but am not clear about which would be best. Is it better to contact the composite manufacturer or the light manufacturer to determine what materials are curable? Also, what would be the benefits of a plasma arc light?

No manufacturer of curing lights or composites will guarantee that a specific light will cure a specific composite unless both the light and composite are made by that manufacturer. That’s why we are cross-testing as many products as we can. The Ultralume 5 is the only LED that we have tested that has the ability to cure all materials. Unfortunately, it’s not quite as easy to use as some other lights and, of course, it still has a cord.

There are virtually no benefits to a plasma arc light any longer. While they do cure faster than most halogens or LEDs, their tips are typically only 7-8 mm in diameter, which means you will probably be overlapping cures, thus eliminating the time savings. They are also quite expensive compared to halogens and LEDs.

I will often use Gluma as a desensitizer/rewetting agent following the total etch technique prior to placing the primer/adhesive. However, we have been wondering about the use of Gluma and SEPs. Would the use of Gluma prior to the application of an SEP affect the already limited etch (or perhaps modification of the smear layer) of these SEPs?

Since you don’t need to desensitize or rewet prior to using a self-etching adhesive, there would be no reason to use Gluma or any similar product. Therefore, we have not tested any desensitizer in combination with a self-etcher.

I recently attended a seminar by one of your contributing editors. In the course of his discussion on bonding techniques, he said that flowable composites could be used to bond porcelain veneer along with the proper tooth and veneer preparation described in REALITY. Is this correct? If so, are there specific flowables that are better than others?

Flowable composites are basically just slightly modified resin cements. As such, any of them can be used to lute veneers. The only limitation would be the viscosity. Some flowable composites do not even flow - they are too viscous!

I have a patient who wants a metal fused to porcelain Maryland bridge. I typically do not do this procedure and was looking for a good cement for this. I was using Unicem for similar procedures, but the self-cure bond strengths do not look good. Duolink from Bisco seems to have good self-cure properties. Do you think this would be good? If not, can you recommend a different one? What would be the recommendation on preparing the metal? Also, how do you think Fuji Plus would hold up? I can’t find bond strengths on these cements in REALITY.

Panavia 21 is your best bet for bonding a metal-based RBB. Be sure to use phosphoric acid on any unprepared enamel. Another good choice would be C&B Cement Luting Composite. If the metal is nonprecious, just refresh the sandblasting inside the wings and bond. With Panavia 21, you don’t even need a primer on the wings if the metal is nonprecious. With C&B Cement, you’ll need to use a metal primer like Alloy Primer. If the metal is semiprecious or precious, tin-plating the wings is fast and effective, then proceed as if it were nonprecious.

Dr. Michael 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. For more information on REALITY and to receive a complimentary issue of his monthly update, REALITY Now, call (800) 544-4999 or visit