How to produce a readable “equigingival” margin without retraction cord

Margins are supposed to be invisible to the patient, not to the technician. Here’s a trick that assures an easy-to-read finish-line.

by Martin B. Goldstein, DMD
Wolcott, CT

Sometimes we have to place our crown margins subgingivally. We may be chasing deep caries or prepping a tooth with an amalgam MOD. And of course, adding a 2mm ferrule to a crown over a post&core usually puts you into the sulcus.

But truth be told, over the years most of the subgingival margins we’ve placed have been purely for cosmetic reasons. It was the best way to hide a pfm margin.

Think back! Even when subgingival margins were the rule, we all feared the long-term periodontal consequences of what we were doing. To add insult to periodontal injury, those “esthetic margins” that looked terrific at the first recall, were often visible as black lines just a few recalls later. Ring a bell?

With the growing popularity of all-ceramic restorations, the subgingival prep is being replaced by a finish line at (or just above) the gingiva.

From the tissue’s point of view this is a vast improvement. When we place the margin supragingivally there’s no subgingival plaque-trap. Moreover, the likelihood of an over-contoured restoration, one with a bulky emergence profile, is all but eliminated.

We find less need to disturb the tissue by packing retraction cord and there’s virtually no chance of a free gingival curettage during tooth preparation.

While this newer approach to finish lines can make our lives easier, from the technician’s point of view, these so-called “equigingival margins” can be difficult to read at times.

Take a look at this case done recently (Figure 2). The finish line simply disappeared into the gingiva. Taking an impression in this manner might leave the true crown margins open to interpretation.

One option was packing retraction cord. But I’m going to admit something here: Packing cord is not my favorite dental procedure. It’s time-consuming - annoying - and when I pull the cord, I often trigger bleeding. So in addition to the time I spend packing, I have to add the time I spend staunching the hemorrhage.

So instead, I created a quick mini-trough using a fine wire tip in my e-surge (Figure 3). It took me just under three minutes for both crowns combined! The spark runs ahead of the probe, so I can avoid touching the teeth. And because it cauterizes as it cuts there’s little or no bleeding.

As you can see (Figure 4), this small tissue modification left the margins beautifully readable. I frequently use electrosurgery around posterior preparations to improve the clarity of my impressions. Take note: I’m less apt to use this approach in the anterior, however, because even the slightest variation in the height of the healing tissue may impair the esthetics. The exception would be intentional crown lengthening and or tissue sculpting prior to preparing a veneer or anterior crown case. In such instances, the E-surge is the poor man’s laser producing very satisfactory results.

In praise of dinky little applications

I’m a huge fan of electrosurgery. I use it daily; sometimes several times a day. I rely on it so much, in fact, that I’ve a surge located in each operatory.

Over the years, Parkell Today has printed a number of good “How to” articles concerning electrosurgical procedures - How to do a frenectomy ... How to remove tissue tags ... How to modify a crown’s emergence profile.*

In comparison, mini-troughing prior to impressing seems like a trivial application. Well, you’re right. But that’s my point!

Many of the e-surge procedures that make my practice easier are “dinky” little applications like this.

When my assistant seated this patient, I hadn’t intended to use electrosurgery. It wasn’t till I completed the preps, that I decided to modify the tissue. If my surge had been in another room (even on a mobile cart), I wouldn’t have taken the time to drag it in. I would have just gritted my teeth and packed some cord.

One secret to getting the most out of an electrosurgery unit is to always have it at hand, turned on with the indifferent pad in easy reach. No matter where I’m working, I have a device at my fingertips. As a result, I find myself routinely using electrosurgery on cases where I hadn’t originally intended to. If I run into a small hemorrhage, I can quickly cauterize it. As alluded to above, electro-surgery has even made my cosmetic dentistry more “cosmetic.” If the tissue contour doesn’t look quite right to me when I’m evaluating a patient for laminates, and adequate sulcus depth is present, I’ll often fine tune tissue contours at the preparation/impression visit. Healing in the presence of bisacryl provisionals occurs uneventfully.

I admit that electrosurgery lacks the sex-appeal of a soft-tissue laser. Though they both do pretty much the same thing, an e-surge can’t compete in terms of WOWING the patient. But at $7000-10,000 a pop, I’d have to think long and hard before I installed a laser in each operatory. But at just $600 for an e-surge, it’s a no-brainer.

Dr. Goldstein is a 1977 graduate of the University of Connecticut School of Dental Medicine and practices general dentistry in a group setting in Wolcott, Conn. He enjoys promoting the cosmetic side of his practice and has found it helpful to incorporate digital photography into his daily routine as a practice builder. Recently, Dr. Goldstein has been appointed to the staff of Contributing Editors at Dentistry Today. In addition to writing for Dentistry Today, Dr. Goldstein also writes for DentalTown, Contemporary Esthetics and Dentistry, the UK’s version of Dentistry Today.

Doctor Goldstein can be contacted at martyg924@cox.net or at his office at 203-879-4649. He is available for speaking engagements on both digital imaging in dentistry and the use of high tech methodology to further the cosmetic practice.

His step-by-step technique article discussing Direct Bonded Veneers (Report #47: The Three-Hour Cosmetic Rehabilitation) can be found here [PDF format]

For a summary of Dr. Martin Goldstein's upcoming lectures and courses, go to
http://www.drgoldsteinspeaks.com