6 things to keep in mind for successful impressions

Dr. Tim Bizga, DDS, who is in private practice in Parma, Ohio, has a unique background that gives him an unusual perspective for a clinician. He started his career as a lab technician, then moved to chairside assistant, and after graduating from dental school, became a clinician himself.

With crown and bridge treatments generating major revenue for many practices, he believes dentists should consider impressions a vital component of their bread and butter. When they don't, it creates problems in the lab. We asked him to share his views on taking-and making-a good impression.

What is the state of impressions today?

The state of it is that we could do a better job. What you send out is what you're going to get in return. We used to have a saying in the lab: Garbage in, garbage out. If we can do things to make the quality better for impressions, we're going to have a better result long-term.

What are some ways clinicians can make the quality better?

First, you have to have care and attention to detail. Whether you're taking digital or conventional impressions, both require a level of detail to ensure that you don't have errors. And then, not giving the lab whatever and saying "Oh, just make it work."You hear that a lot when you're on the lab side. That frustrates technicians. 

Why is it frustrating?

With all these materials, they have parameters. If you're looking at the scientific side of it, the lab needs a certain amount of reduction. They have checklists that they run through on the lab side. How much margin do you have? Is it a shoulder? Is it a chamfer design? Is it a feather edge? How is material support? That all comes from the science. They all have these numbers that we have to live by in terms of how much reduction to have and margins so that you can get something that you say should last X number of years.

For instance, if you're picking something like a Porcelain Fused to Metal, which has been around for decades, you have to have 1.5 to 2 mm of occlusal reduction. Most dentists under-reduce because they're trying to be conservative. You have to have room for the metal. You have to have room for the porcelain. You have to have room for the opaque layer. If it's short, the lab will say, "Well, the occlusal reduction is inadequate.” The dentists will say, "Just do your best.”

What happens is the porcelain area in that area of the crown gets thin. Because it's thin, there's a high likelihood that if they bite the right thing, like a nut or something very hard, and that material isn't the proper thickness, it can chip or break. That can happen in week one or that can happen in year two, and there's no way of telling. You don't have a crystal ball.

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Are there any innovations right now that have you excited about the future of dental impressions?

Clinicians should expect the most from their material in order to do the best job. This means high tear strength, high hydrophilicity, precision placement options, appropriate set and work times and good material flow. There are enhancements to the standard impression materials coming that deliver the best performance not only across all areas of the procedure, but also in how it handles with the presence of fluids. In a lot of cases, dentists ask "Does it work in blood?” They always want to know if they have to be strict with their tissue management because polyvinyl siloxane materials are hydrophobic. So manufacturers have to add certain things to make them behave better in the presence of saliva and blood. You still want to make it as dry a field as possible when you're taking an impression, but the new materials seem to behave extremely well in the presence of fluids, which is unlike most of the older materials. 

Everyone says scanning is the way to go, and yet people still make traditional impressions. Can you explain why?

It's a business. The fees for service are set where they are so you also get to take home a paycheck, which, in America, shouldn't be a bad thing. But dentists are getting hosed by the insurance companies. That's the problem. It's all about return on investment for dentists while watching their return for procedures go down. Sometimes it's just easier to stay with impression materials.

Things have changed since 2007-2008. When that whole mortgage meltdown happened, buying patterns changed. Things changed in dentistry, and some people are still trying to figure it out, believe it or not. People have changed. I travel all over, and I find that it's different. Our patients don't feel prosperous. I don't think the country feels prosperous. 

Why haven't all people adopted scanning? Because you've got to have the extra cash. You don't want to finance everything; you want to try and make a smart investment.

Related reading: How digital scanning increases speed and convenience in the dental practice

What is the key takeaway every clinician should have about dental impressions?

Do your best even when no one is watching. Sometimes in school, you had that pair of eyes over your shoulder, and you always tried to produce your best. But now when you're in the privacy of your own little practice and nobody is out there judging your work, sometimes it's easy to cut corners and send it off to the lab. 

I went to a Jesuit high school, and they used to make me sign every one of my papers with the Latin symbol AMDG, which stood for "ad maiorem Dei gloriam." It was your honor code. It stood for the greater glory of God. They said if you put that on your work, you're saying you did your very best. 

When you're writing your lab script, and you sign your name, I look it as saying you did your very best. That's the takeaway. When people put that kind of standard to it, it's hard to lose.