How to Fix a Tooth With CAD/CAM (CEREC)

Intro: How to Fix a Tooth With CAD/CAM (CEREC)

This instructable is about CEREC, a powerful CAD/CAM technology designed to fix teeth.
This is important because this technology is increasingly being used nation wide.

Why this matters:

1. It's here to stay.
   • Corporate mills, private practices, and national dental labs are adopting this because it's faster and cheaper--frankly insurance doesn't pay like it used to.
   • Patients love one visit crowns.
2. New possibilities for patient treatment.
   • If you can do something faster, cheaper, arguably better--why not?
   • Less sensitivity--Milled restorations have much less shrinkage than composites and less thermal conductivity than silver.
   • Quickly replaceable--break it? No problem. Mill a new one from a saved file.
3. CAD/CAM is cool

Note: Gold is the very best restoration in existence.

• It lasts longer than a ceramic crown.
• It spares the enamel from the opposing tooth
• It will not fracture catostrophically
• But it costs over $1700 an oz. 

Note:
At the time of writing, the author has no financial connections to Ivoclar, 3M, Patterson, or Sirona.

Note 2:
Sorry for taking so long! 
The community has been doing such a great job, that I couldn't think of anything of worth contributing until recently.
Feel free to PM me with any ideas you'd like covered.

STEP 1: Capture a Reference

To make a restoration, the CEREC needs a 3-D model.
This model is made by taking an optical scan.

In the case of the BlueCAM (formerly state of the art), it involves stitching multiple images together.
For the OptiCAM (released late last year), the scanner creates a 3-D image by compiling from a video feed in live time.

1. Start one tooth distal (to the back) to the main tooth to one tooth mesial (to the front of the prepared tooth).
2. Have a steady hand.
3. Capture the smallest area required.  For the bluecam, try to have no more than 3 images to the model.
4. Less data-> faster processing.

STEP 2: Cut the Tooth. Scan.

1. Cut the tooth.
   • CEREC needs at least 2 mm of occlusal clearance (2 mm cut off the top) for the porcelain to stay strong.
   • 1 mm axial reduction.
   • Try to have a clean preparation--preferably above the gumline
2. Scan prepared tooth.
   1. Dry.
   2. Powder (if bluecam or earlier)
   3. Scan 

Follow the same guidelines as before.

Again, try to minimize the number of scans to speed up processing power.

STEP 3: Design Restoration

Good design respects the harmony of the mouth.

My observations:

• Interproximal (side to side) contacts are important.
  • A poor contact results in good getting jammed into the gums.
  • Often Food gets stuck. Gums get damaged. I recommend beefing the contacts to yellow. 2.
• CEREC tends to make a light occlusion  (a light "bite").
  • This minimizes occlusal adjustments, but is based on the assumption that teeth will supraerupt into position.  There will be a slight shifting of other teeth.
• Most patients don't care about tooth anatomy (the valleys and ridges on the top of the tooth).
  • However a good dentist tends to pay particular attention to having

For anterior cases, you *will* need to tweak things by hand. CEREC tends to create an adequate margin, contacts and occlusion. Heights of contour tend to be oversimplified and "fake" looking.

Note: There is a very well done CEREC anterior case on Youtube. 
However, it doesn't mentiont that a master ceramicist did a final cutback, build up, and glaze prior to placement. 
Of course it should look good!

STEP 4: Mill

Choose the shade, material, and size.

• Dilithium silicate (e-max) is chosen for crowns and posterior onlays due to it's great toughness.
• Empress is chosen for inlays and anterior onlays due to it's easy machinability and esthetics.

Translucency

• HT- high translucency; for relatively esthetic looking restorations.  Tend to mimic enamel.
• LT- low translucency; for teeth that have been heavily stained.  Tends to block out dark spots.

Mill.

STEP 5: Try In.

• Check margins and contacts.
• Grind off sprue (the thin rod that sticks out after milling).

Don't check occlusion until the restoration is cemented.

• This is because the cement film may slightly change the height of the restoration.

STEP 6: Stain. Glaze. Bake

1. For the most lifelike restoration, stain it:
   • Most teeth aren't one color.
   • Darker stains in groove.
   • Increased chroma at neck of the tooth.
2. Glaze.
3. Bake.
   • Most porcelains are fairly weak until baked.
   • The baking initiates cross-linkages in the material that greatly prevent against fracture.

STEP 7: Cement. Adjust Occlusion

Cement the restoration.

Adjust the occlusion:

• If the bite is too high, it will hurt to bite on the tooth.
  • If the contact point is too large, additional stress is placed on the periodontal ligament.
  • This results in great pain that is usually triggered on biting.
  • Additionally, the tooth will be increasingly sensitive to cold.
  • Generally, this can be diagnosed because the pain is quick onset, quick offset--seconds, not minutes.
• CEREC and many labs default to a crown slightly out of occlusion.
  • The theory is that a tooth will supraerupt and the crown will raise to the right place
  • Unfortunately, this doesn't work for implant crowns (which won't erupt)
  • Personally, I feel that this is mainly a matter of laziness and I like my crowns to perfectly occlude.
• For an ideal contact, aim for point contacts in harmony with the original occlusion.

Occlusion is pretty complicated.
Frankly, it is one of the most important things that a dentist should know.
Personally, I recommend Kois, Dawson or Pankey to have a good grasp of it.

Strangely, occlusion (how teeth come together) is one of the most controversial topics in dentistry.

STEP 8: Strengths and Weaknesses

CEREC is a powerful technology that offers some strengths, but has serious flaws.

Strength:

• Convenient.
  • Immediate results.
  • No temporaries to break or fall out.
  • Less gas for patient.
• Cheaper
  • Less visits--less overhead: sterilization, drapes, sleeves, staff time,
  • A block of Ceramic is far cheaper than a ceramic crown.
• Quality control
  • Many labs are "off-shoring" work to Asia.
  • While some labs are great, many labs use mystery metals and techniques with no oversight.
  • Many domestic labs are also dropping in skill as experienced lab men are leaving.
  • Lastly, most domestic labs are making CAD/CAM milled crowns as their standard restoration

. Cons:

• More tooth has to be cut.
  • More tooth cut--> tooth more prone to failure.
• Inferior fit and durability to a good lab crown.
  • A good crown is built to the tooth.
    • Margins will stay intact indefinitely if hygiene is maintained and be *much* more resistance to breaking.
    • There is less space for washout.
  • The milling bur of a CEREC unit is fairly large, and will create various gaps in the restoration unless the tooth is prepared into a formless blob with minimal line angles.
    • *However,* a CEREC can be remade the same day, same hour. No problem.
    • With newer resin-modified cements, it is impossible to clinically see the difference in the short-term.
• Inferior long-term esthetics CEREC stains wash out easily. However, most people don't care.

STEP 9: Final Thoughts.

Final note: what would you choose?

1. Faster, cheaper, replaceable, one visit?
2. Longer lasting, better looking, more time, more expensive?

Please tell me what you think!

Note: this porcelain-fused-to gold crown will last forever, saves more enamel, and look great for decades.
However, it takes a lot more time to make, and at least 2 visits from patients:

1. Numbing Shot.  Prep. Impress. Make temp crown. Cement temp crown
2. Wax coping. Invest.  Bake for 2 hours
3. Cast gold coping. Polish
4. Hand stack porcelain base shade.
5. Bake.
6. Cut back
7. Repeat steps 4-6 until happy. Most good labs will have 1-3 cycles. World class ceramicists may do up to 20 cycles.
8. Final contour
9. Glaze.
10. Bake
11. Seat patient in chair. Cement.  Polish

Comments

[T0BY]

Interesting!

[SmilecraftD]

Considering bleaching your teeth? Be sure to discuss the possible risks with your dentist – especially if you plan to use an at-home bleaching system.

See More Information:

http://www.smilecraftdental.com

[SmilecraftD]

We use computer-aided drafting (CAD) and computer-aided manufacturing (CAM) dental technology to provide same-day crowns and other restorations.

See More Information:

http://www.smilecraftdental.com

[amvone]

Hello! I have 2005 Cerec model (red cam) and I'm trying to image the opposing tooth to establish the height of the crown. Unfortunately, I can't find that step anywhere. Any insight would be great!

[mkhiari]

hello i need to build a dental 3d scanner can some one help me please

[steveastrouk]

What an honest and professional Instructable ! Fascinating. I'm amazed how much cheaper Cerec restorations are here in the UK than the USA though - around $600 at my dentists - but he doesn't like them, except for teeth where the aesthetic is less critical. We kicked around doing an UL3 because I was interested in the tech (and NEEDED a crown ;-) ) , but in the end went conventional, for about the same price.

[tylerwhitworth]

Very cool, My mom called me up the other day (knowing how much I want a mill, and a 3d printer) and excitedly told me how she got a new crown that was made this way. She tried to explain it, and did a pretty good job, but it's neat to see how it's done. Thanks for sharing!

[camidumas]

I found this post to be utterly fascinating. By making the educated public aware of the bleeding edge of a highly technical field, one moves that new functionality a bit closer to common usage. I really appreciate harmless matt taking the time to provide this kind of esoteric information (and like another poster, dream of the day I can print out a new tooth, however far off it may be).

[biospot]

This seems to be for dentists. Its not the thing I can do at home and I REALLY wish I could. My wife needs implants and crowns and I need one too. The total cost will be $10-$15K when the dust settles and anything that could help by making that cheaper would be a big help. We just have empty spaces now and it will remain that way until something like this drops the price to where we can afford it.
Any idea how to get this done in more economical way that going to a dentist and having them do it? By the time big corporate makes it's profit and I have to pay my share of lost malpractice lawsuit awards, I just can't afford the costs.
This would be one answer to this problem.

[Morphik]

Well, you might consider going abroad for that. My sister lives in Bangkok and tells me that it's cheaper to travel there, have your teeth fixed and stay at the hotel than just having your teeth fixed at home (in France for me, where health insurance is good). Don't be afraid, Thaï doctors are very good, they speak English, and the food is so good (though spicy).
I'm sorry for this comment which not really related to the instructable, but teeth are so important.
Fascinating technology anyway.

[londobali]

yes!! i totally agree!!
Take a vacation to another country.. have your teeth fixed there..
It'll be way cheaper (including the tickets) than your numbers, plus you get the vacation for "free"...
:)
Singapore is also quite famous for "medical-tourism"..
Or if you want to come to Bali, i can point you out to a couple international standard dentist around here..

Sorry harmless matt, I understand that it was a big investment you made, but still, what can guys like 4sc4n10 do in this case?

[picturesofsilver]

I can't recommend going out of the country. Not to Mex on the border anyway. I thought I had a good dr; he and his dad had been in business for 2 generations. He did 8 teeth, upper fronts for $2000. After he got through with me, he put on a bridge; not individual crowns. I developed a gum infection, when the dentist saw my teeth, she told me there was impingement and a bad tooth that caused the infection. He had told me all my teeth were good and I did not need any root canals. To make a long story short, it cost me 14,000 to fix his job. He shaved my teeth off too short, so I had to have 4 root canals. They couldn't do straight porcelain crowns, I had to have silver bases b/c my teeth were so short. I could not floss with the bridge which was another reason I needed it off. My mouth had a dull ache all the time. The Mex dr told me I just needed to get used to them. When the US dentist took off the bridge, she took photos. She said it was abuse and my gums looked like raw hamburger meat. I had dead tissue under one tooth that had to be debrided. I cried for several months while I did medicinal rinses to clear up my gums. My home dentist told me Monterrey would have been a safe place to have work done, but not the border; they do not have the same standards in other countries that we do here. Of course I know you can run into prob here as well, but less probability here. I never want anyone to go through the nightmare I had to go through.

[harmless matt]

Sounds typical.

I'd see that all the time from people flying to China, India, or Latin America for work.

It's more expensive to fix it (IF it's fixable), than to do it right the first time.

[picturesofsilver]

hindsight is 20/20. veneers would have been cheaper and more beautiful done in the US. Thank God when I smile and I smile a lot, my gums don't show so you don't see the gray gumline from the silver bases. I'm just thankful not to be hurting and no running pus from my gums! Matt you are right on the 'IF' it is fixable. There are dental schools in major cities.

[harmless matt]

4sc4n10 is the relative of a sister in Bankok.

In terms of biospot's problem, I don't have enough information to know.
I would recommend contacting the local dental society.
There are often altruistic dentists that go out of there way to help needy people.

However, I have to add that I've personally been burned helping the poor many times: at my first practice in Oakland, at a nonprofit (that will remained unnamed), and at various events like RAMM and MOM that I've served at.

I'd advise against medical tourism, but I don't have first-hand knowledge of what's done outside the US. I would recommend going to a dental school instead, as it's significantly cheaper (but slower).

For guys who really have low income and want good solid dentistry, a dental school is probably the way to go. Free clinics can offer patchwork dentistry, but aren't equipped for bigger cases usually. Most of the foreign work that I've seen is downright junk--with the exception of some of the University work from top institutions (there was a patient who's cousin was the head of the dental program in Argentina).

[leedawg]

In response. This machine costs 150K to purchase plus software updates and revisions as well as hardware updates. As a clinician myself id love to be able to provide a crown to you for under 1k. What many forget to take into account it cost me as a clinician 8 years of upper education to be able to render these services to you, not to mention the school debt which is more than many peoples mortgages at an interest rate that is over double what the average home loan is going for.

The blocks of material that are milled into the crown are a consumable cost as are the cutting tools, I have to pay 3 different employees a fair wage so they can put food on the tables for their families and I have to pay the power company water company and garbage to make the office inhabitiable. By the time you add up all of these costs unfortunatly a crown has to cost 6-1000 dollars. There is not much of that cost that I take home at the end of the day.

When you start talking implants think about the risk involved and what we are working on is not a piece of metal that behaves the same way each time you cut into it. We have to deal with biology and physiological responses of tissues to invasive procedures. Everybody responds differently. If everything goes just like it should then an implant is profitable to the practitioner however one thing goes wrong or not as expected you will usually just be lucky to break even in costs of materials and time to follow up with that patient. For much less that 4k an implant it becomes hard to make doing these procedures worth your time.

The real problem in society today is peoples perceived value in their oral health. Most of us have no problem buying the new iPhone every year it is released or getting the new 50 inch led side lite 1080p tv.

Again I wish I could give dentistry away at far less than what it costs but that would mean companies would need to sell the things I need to do the job for far less and my education would need to be free from the govt and in the world we live in here in the united states that just is not going to happen. You can thank capitalism for that.

So not to rant but hopefully more so to educate you and anybody else reading this what goes into what we do and perhaps why costs are what they are. In my opinion we are not compensated enough for what we sacrifice in school today and the debt taken on as well as the battle constantly fought with insurance companies.

[harmless matt]

Amen!

Oh, and the CEREC is more like $170,000 + now

[biospot]

I wish I could afford to pay the dentists so they could do this procedure. I just don't have the money. Sorry for your money problems, but I have a company provided IPHONE that I use for free. I have a 23 year old car that I bought new and I fight the cable company tooth and nail for every $3 price increase on my cable internet (ONLY) bill. I am not a rich stingy person, I am a poor stingy person, and if this option can (someday) provide I and my wife a cheaper way to replace our missing teeth, we will be very happy indeed.

[harmless matt]

This is for the general public.

CEREC requires a minimum of $170,000 with at least $6000 a year for technical support and software updates. It is only cheaper with volume...which can influence the owners to prescribe CEREC for everything.

In terms of the expense of dentistry, I think that we're vastly undercharging for a highly technical, highly expensive skillset. We have the most expensive education (way more expensive than MD's), high overhead (staff, supplies, equipment, school fees), and we are squeezed by insurance companies. Frankly, I'd say to drop the insurance and get a health savings account. Budget for the dentistry, and realize that it's an investment in quality of life.

Going to a good local dentist is actually the cheapest way to do it. Corporations seem cheap--until you realize that they make up the difference in volume and "upgrades." Ask your local dental society.

My answer is prevention, and I hope to create a grassroots movement to eradicate tooth decay by the end of my career.

[harmless matt]

Let's keep this civil.

I'm a nerd dentist, and like to keep abreast of research.
I am *not* a researcher, but friends with many.
I don't consider anything that I'm presenting as cutting edge--just normal stuff.

I'm just reporting what I've read, and what I hear.
Look it up on pubmed.

I'm done responding.