Three things you can do today, to improve the quality of your adhesive dentistry

and it doesn’t matter what materials you’re using

By Nelson Gendusa, DDS –
Director Research
Richard Goldman, DDS, FAGD –
VP Clinical Dentistry

Here are three hints we gleaned from recent issues of our Adhesive Newsletter to help you achieve more predictable results from your bonding efforts. One of them involves new research. One is a golden oldie that’s too often overlooked. And the third is a “universal truth.”

Don’t wait till the final restoration is delivered to apply the bonding agent.

There are lots of reasons to apply a bonding agent to your crown preps at the preparation appointment – even if you don’t intend to bond the final crown.

With a resin hybrid layer sealing the prep, the tooth will be dramatically less sensitive during the provisional period. The dentin and pulp will be protected from fluids, the bugs and toxins that inevitably creep in at those leaky margins. The tooth will be protected from the dreaded black skuzz that can discolor provisional crowns. Furthermore, most patients won’t have to be numbed when you’re ready to remove the temporary and cement the definitive crown.

And if you plan to bond the final crown, there’s another compelling reason to apply the bonding agent at the preparation appointment –

A growing number of studies are suggesting that dentin and enamel are most receptive to bonding immediately after preparation. In other words, you’ll get a better bond if you apply the bonding agent after prepping than if you wait a week or two till you’re ready to bond the definitive crown.1, 2

Here are a few suggestions for applying the bonding agent immediately after preparation ...

• If you make temps directly in the mouth, do it before you apply the bonding agent. (Otherwise the temp will bond to the tooth!)

• If you use a vinyl polysiloxane impression material, take the impression before applying the bonding agent. (Residue from the bonding agent may inhibit the set of the impression.)

• Use a thin-film bonding agent like Brush&Bond – not a thick bonding agent like Clearfil SE. Remember, the bonding agent is applied after the impression.

• If the final crown will be bonded … At the cementation appointment, clean the prep with phosphoric acid, apply and cure another layer of bonding agent, then cement with your resin cement.

If you’re concerned that the two layers of bonding agent may cause fit problems, don’t be. The typical marginal gap in a well-fitting clinical crown generally runs 35-75 microns. At the maximum, two layers of Brush&Bond would only be about 18 microns.

Bonding metal: A blast from the past

The call came in about 5:00 pm.

According to the dentist, a threaded post had broken in the implant. He’d drilled out the broken segment … taken an impression, and had his lab cast a replacement in high-gold alloy.

Apparently another dentist had told him that if he expected the cast post to stay in the implant, he needed to bond it with C&B-Metabond. So he bought a kit. He even invested a little extra to get the MTL-V primer to boost the bond to the gold alloy.

Now could we just run over the procedure step-by-step?

US: Sure, no problem. First, blast the gold post with aluminum oxide at about 80psi. Then using a rubber dam to protect the soft tissue, blast down the hole in the implant.

HIM: Don’t have a blaster. I’ll use a diamond.

We did the best we could do for the dentist. We talked to him and his assistant for maybe half an hour. We even typed out a suggested procedure and FAXed it to the office so they’d have something to refer to as they worked.

But the fact is, without first blasting the metal, C&B-Metabond will only deliver about half the retention it’s capable of. Hopefully that would be enough for this case. But considering what’s riding on the bond, wouldn’t it be nice to assure that it was as strong as it could be?

It’s been a few years since we mentioned how important it is to air-abrade metal before adhesive procedures. A diamond is a very poor substitute. Air-abrasion does at least 5 things you’ll never achieve with a diamond.

• Air-abrasion triples or quadruples the surface area you’re bonding to. Diamond-abraded surfaces APPEAR rough to the naked eye, but under a microscope they look like clapboards on a house. Broad smooth areas interrupted by parallel ridges. In contrast, an air-abraded metal surface looks like a satellite view of the Himalayas.

• Air abrasion cleans the surface by stripping off contaminants and excessive oxides.

• Air abrasion creates millions of small undercuts, so it supplements the cement chemical adhesion with micro-mechanical retention.

• Air-abrasion “work hardens” the metal surface, which may make it more chemically reactive.

• Air abrasion raises the surface energy of the metal. This improves wetting properties, so it achieves more intimate molecular contact with the adhesive.

Blasters are a cheap investment in the quality of your bonds to metal. In fact, they’re probably cheaper than a kit of your favorite adhesive cement. For example, our AeroEtcher costs $179.99 (pg. 18). Danville Engineering also makes a good one.

Get a blaster. And use it any time you’re bonding to metal.

And finally, THE MOST IMPORTANT THING TO KNOW about any bonding agent...


A young dentist was on the internet asking what kind of long-term success dentists were having with Brush&Bond. Apparently he’d been using the stuff a while and hadn’t noticed any problems - but he was worried that he wasn’t using it quite right.

He described his technique -
1) After prepping, he applied Consepsis®
2) He then etched the tooth.
3) He applied Systemp^® Desensitizer.
4) Then he applied and cured the Brush&Bond.

He was a little concerned because his partner used a similar technique with B&B but really scrubbed the tooth with the desensitizer to “disrupt the smear layer.” He was wondering if maybe scrubbing might be a better approach than blotting.

WHAT IS IT WITH YOU GUYS?

Why is it when some dentists adopt a new product they’ll get their technique from their partner, or last weekend’s guru, or REALITY, or even some stranger on the internet. HEAVEN FORBID they should read the instructions that came with the product.

Here’s the most important thing to know about your bonding agent ... (Write this down. It’s important) ... The world’s foremost source for information on the proper technique for any product is the company you bought it from.

Think about it. It’s in the company’s best interest to see that you get good results. And if they’re doing their job properly, their instructions will be based on the combined input of their chemists and the collective feedback from dentist-users.

For the record, here’s the technique we recommend for bonding to dentin and cut enamel:

1.) Apply Brush&Bond using the special applicator brush.
2.) Let it sit on the tooth for 20 seconds. Don’t thin it. Don’t agitate it. Don’t rub it. If the tooth seems to dry out, we’ll let you add some more - but that’s all.
3.) Dry it with air.
4.) Light cure for 5-10 seconds.

If you ever have questions about our recommended technique, feel free to call us (1-800-243-7446) or send us an e-mail (info@parkell.com).

Now concerning this particular dentist’s embellishments to the technique ...

Disinfecting –

I’ll grant that “disinfecting” preparations sounds right and most studies suggest that Consepsis won’t hurt the bond. It may even help it. But there isn’t much research suggesting that disinfection offers a real clinical benefit. Many good dentists routinely disinfect their preps and have good results. Many good dentists never disinfect their preps and have good results. I’m skeptical that disinfecting makes the patient feel any better, but it obviously makes many dentists feel better.

Etching -

If you truly enjoy etching, plus rinsing, plus drying - you can do that too I suppose. But unless you’re bonding to uncut enamel, it probably won’t add anything to clinical performance.

And as for using a separate desensitizer -

Don’t do it! Don’t dab on a desensitizer. And certainly don’t scrub with one. Numerous studies suggest that a separate desensitizing step can interfere with the bonding mechanism. Besides, Brush&Bond itself is one of the world’s most effective desensitizers. So applying an initial desensitizer before B&B may actually increase sensitivity.

2 Magne P, et al. Immediate dentin sealing improves bond strength of indirect restorations. Jour Prosth Dent. 94:6, p511-519, Dec 05
2 Nikaido T, et al, The resin-coating technique. Effect of a single-step bonding system on dentin bond strengths. Jour Adhsv Dent. 5:4, p293-300, 2003

For more information about AeroEtcher click here.
For more information about C&B-Metabond click here.
For more information about Brush&Bond click here.

©2007 Parkell, Inc. Notice