CEREC at Amy Guthrie, D.D.S.

There's something about the nature of dentists that draws them to new technology. But while many hi-tech tools look and sound amazing at first, when you get right down to it, they don't have a lot to offer where it counts--helping patients. So our approach at Amy Guthrie, D.D.S. has been to wait for the technologies to mature and prove themselves before jumping onto the bandwagon.

We have recently (spring 2002) started using some amazing technology that more than meets our requirement of substantial benefit for our clients. It's called CEREC (for CEramic REConstruction). It works by replacing the physical processes used to make a "part" for a tooth with a 3-d camera, some computer software, and a small but sophisticated milling machine in the office.

CEREC often works better in your mouth than traditional restorations while being far more convenient for you to have done!

Here's more information, organzized as an FAQ (frequently asked questions). Click on your question, or just scroll down.

Note: I, Rich Acuff, am not a dentist (and I don't play one on TV). This overview I've written is intended just as a description for the non-doctor. It is not intended to replace a detailed discussion with your dentist!

How is CEREC better for my mouth?
How does CEREC make life easier for me?
What will my CEREC look like?
How is CEREC different from other restorations?
Is CEREC safe?
As Bob Vila says, "yeah, but what does it cost?"
When is CEREC the right choice?
Exactly how does the CEREC system work?
Where can I find out more about CEREC?

Email us or call if you don't see the answer you need!

How is CEREC better for my mouth?: CEREC has lots of nice properties we've been looking for since before Paul Revere used walrus teeth on George Washington:

Tooth Compatible
The ceremic material used in CEREC is as similar to natural tooth (enamel) as anything yet devised. The hardness and abrasiveness are very similar to natural tooth, so we don't have to worry about the CEREC beating up on the opposing tooth, or being worn away by it.
CEREC material also expands and contracts with heat and cold much like natural tooth, allowing less stress to your teeth when you eat and drink hot or cold things.

Lets you keep more natural tooth
CEREC restorations are bonded (glued) into place, effectively replacing the missing part of your tooth to form a continuous structure. To make sure Traditional restorations stay in place, otherwise healthy tooth structure must be cut away to provide the shape needed to lock in the restoration (mechanical retention). Often, CEREC allows the dentist to limit cutting to only the damaged part of the tooth.
For traditional restorations you'll typically need to wear a soft "temporary tooth" for two weeks or more while the lab makes your final restoration. The problem is that thinner, weaker areas of tooth are not well supported by a temporary, and could easily break during that time. So the dentist has to cut down those parts to make sure the tooth is strong enough to last with a temporary. Since no temporary is needed with CEREC, the dentist is free to keep every bit of tooth possible.
Here at Amy Guthrie, D.D.S., we think keeping your natural tooth intact a very good thing.

Lasts a long time
The data is still preliminary, but all indications are that CERECs will last a long time; as long as or longer than their lab-made porcelain counterparts. The first CERECs were done in around 1983, and lab-made ceramics go way back.

Looks like tooth!
The CEREC material comes in various colors that closely match most natural tooth shades. In fact, it's often difficult to spot the restoration after it's bonded into the tooth.
How does CEREC make life easier for me?: If you've had an inlay, onlay, or crown done, you know it's a bit of a hassle. You have to make two trips to the dental office two weeks apart, and in between you have to wear that temporary that, no matter how hard we try to make it right, is always a little bit uncomfortable, ugly, and weak, and then it sometimes falls out, so you have to make yet another trip to the office.
Well, CERECs are usually done in just one visit! That means:

only one trip to the office
(Amy will kill me, but I'm gonna use the 's' word!) you only need to feel one shot.
no temporary to mess with (including saving the 1/2 hour it typically takes to make it)
no yucky goo in your mouth to make a mold of your tooth (it's done with a 3-d camera)

Then, since CERECs should last a long time, you should save more time not coming back!
What will my CEREC look like?: Thanks to the translucent, tooth colored ceramic and the blending nature of the bonding agents, a tooth restored with CEREC looks like, well, a tooth. Some people have teeth with different colors in the same tooth, and CEREC may not be the best way to restore a front tooth in a case like that, but much of the time you can't even see the CEREC after it's installed, polished, and the tooth rehydrates (a tooth looks whiter when it gets dry during the operation (and by the way, that's one of the reasons the super-fast teeth whitening systems appear to give great results at first, only to darken up later)).
How is CEREC different from other restorations?: CEREC is a form of indirect restoration. For indirect restorations, the tooth is prepared, then a new piece is manufactured outside of the mouth. With CEREC that happens in about 20 minutes while you relax. With these others it takes about 2 weeks while you live with a temporary. All the indirect restorations are close to the same price. Here's the run down:

Type Advantages Disadvantages

Porcelain Skilled technician can do good "art" to produce very natural looking result

Glazed and fired so harder and more abrasive; can wear and stress the opposing tooth
If the fit isn't perfect on the first try, can't really adjust; another long wait

Gold Strongest and toughest material available; good for back teeth of heavy chewers

A lot more tooth must be removed to provide the thickness and mechanical retention needed
Gold color stands out

Porcelain
on Gold Compromise between pure porcelain and pure gold; still fairly strong but also natural looking

Requires removing the most tooth structure to fit the gold and make room for the porcelain
Fired porcelain can wear on other teeth
The porcelain can chip off of the gold over time

The other way to approach fixing a tooth is a direct restoration, often just called a "filling" as the tooth is prepared and then the soft material is pressed into the hole (to fill it), shaped and somehow hardened.

Type Advantages Disadvantages

Composite
Tooth-colored, plastic-like material, good for small defects
Costs less than indirect restorations

Relatively soft so wears quickly
Not strong; can't support heavy chewing stresses
Cannot be very large

Amalgam
Least expensive option, usually
Can fill large voids

Silver to black color
Stains teeth; can show through from back
Softer than enamel so wears
Temperature changes can weaken it (differential expansion)
A lot of tooth must be removed to provide mechanical retention
Is CEREC safe?: The new part of CEREC is how the restoration is made, not what it is made of, so while it's impossible to be 100% certain that no person out there can have a bad response to the materials, they have a long track record of being safe and reliable, and are widely accepted as the standard of care by dental authorities.
As Bob Vila says, "yeah, but what does it cost?": The joy of technology that actually works: we're able to offer the many advantages of CEREC at the same price level as the other indirect restorations. Our experience so far is that most dental plans provide the same coverage for a CEREC as they do for a full-coverage porcelain-on-gold crown, though we've had to write some of them letters of explanation. Hopefully the dental plan carriers will quickly understand that CEREC is better for them in the long run since people will be coming back for more and bigger procedures less often. However, as always, your dental plan is individual to you, as arranged by your plan sponsor (employer, typically) and the carrier, so your experience may be different. If you're concerned about your benefits, contact your carrier and ask.
When is CEREC the right choice?: CEREC is only one of many tools we can use to keep your smile healthy and your chompers chomping. We're happy to talk with you about your individual needs and priorities. CEREC may be right for you if:

You want a long lasting restoration
You want to keep as much of your own natural tooth as possible
You want to minimize the number of trips to the office
You want your teeth to look as natural as possible
CEREC may not be the right thing for restoring a badly damaged tooth in an area where you chew very hard, or for restoring very small cavities.
Exactly how does the CEREC system work?: This part is for the techies, so don't say you weren't warned!
The initial preparation of a tooth is mostly similar to traditional methods. The area is numbed if required and the surgical field is prepared, typically with either a rubber dam or an Isolite. Then a handpiece is used to removed the damaged tooth structure and prepare the proper shape to receive the restoration. Some of the early CEREC systems required the preparation to follow various rules to accomodate the limitations of the milling machines. The new CEREC-3 mills, with 6 degrees of freedom, impose very few limits on the dentist. The main concern the dentist has is making sure the preparation is made so that the camera will be able to "see" all of it (no part is hidden behind another part), and that the "lines" used in the computer design process will be clear.
After the preparation is complete, an inert, uniformly reflective powder is spread over the tooth. This compensates for varying optical properties of the tissues in the mouth. Then the wand-like camera is placed just above the tooth and an image of it and it's neighbors is recorded. The cameral uses its own built-in infra-red light source and special sensors to capture a very accurate three dimentional model of the tooth surface. For each position (pixel) in the image CEREC captures height (X, Y, and Z) data instead of the color data that would make up a normal digital picture.
Now you get to relax and the real fun begins. The dentist uses one of several design methods in the CEREC software to specify your new dental part. Loosely, the design methods are:

Coorelation or, as I like to call it "copy". If you have something that's basically the right shape already, we can take an image of it before preparing the tooth (or sometimes we'll use a model of the tooth), then have the software design a restoration that "fills in" between the original shape and the prepared shape. This method can give great, natural-looking results, but, of course, you have to have something good to image to start with! Even then, the dentist can build up the desired shape out of easy-to-work materials like wax or composite and use that as the basis for coorelation.

Extrapolation is really "build from scratch", handy for small, simple restorations, especially when the surrounding tooth structure is in some way unusual so that the more automatic methods won't give a good result.

Function is really two different modes. One is like an extension of coorelation, but you can edit out a bad spot and have the software fill it back in with idealized tooth shape. The other is used by imaging the opposing tooth and designing the new tooth shape to fit well with it; useful if there is something odd about the way your teeth fit together (occlusion).

Dental Database designs your tooth to be "average" tooth based on an aggregation of data about thousands of teeth.

Endo Crown is used to fill in the "pothole" left after the endodontic treatment (root canal).

Veneer allows us to wrap the visible part of a tooth in ceramic to change the shape and look without removing much structure.

We place various "lines" in the computer, specifying where certain key points should be located, especially the edges of the restoration where it will join with the exiting tooth, and where the restoration will work with the tooth that it chews against. This is where the dentist's skill shines, customizing the look and fit to your specific needs. After the design is complete, an ingot of ceramic is loaded into the milling chamber, and the computer controls the special diamond-tipped cutters as they mill the desired shape to within 20 microns in about 10 minutes. Then the dentist touches up the fit of the custom-made restoration and bonds it into your mouth, and finishes up by polishing the surface.
Where can I find out more about CEREC?: Certainly you can ask us, or you can check out PlanetCEREC for many details.

Type	Advantages	Disadvantages
Porcelain	Skilled technician can do good "art" to produce very natural looking result	Glazed and fired so harder and more abrasive; can wear and stress the opposing tooth If the fit isn't perfect on the first try, can't really adjust; another long wait
Gold	Strongest and toughest material available; good for back teeth of heavy chewers	A lot more tooth must be removed to provide the thickness and mechanical retention needed Gold color stands out
Porcelain on Gold	Compromise between pure porcelain and pure gold; still fairly strong but also natural looking	Requires removing the most tooth structure to fit the gold and make room for the porcelain Fired porcelain can wear on other teeth The porcelain can chip off of the gold over time

Type	Advantages	Disadvantages
Composite	Tooth-colored, plastic-like material, good for small defects Costs less than indirect restorations	Relatively soft so wears quickly Not strong; can't support heavy chewing stresses Cannot be very large
Amalgam	Least expensive option, usually Can fill large voids	Silver to black color Stains teeth; can show through from back Softer than enamel so wears Temperature changes can weaken it (differential expansion) A lot of tooth must be removed to provide mechanical retention

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Last updated February, 2003 by Rich Acuff.