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I love doing crowns on implants with my CEREC machine.

One of the annoying aspects of the procedure is what to cover up the screw hole with when imaging the abutment. I have the same issue when I take conventional impressions for larger cases that need to go to the lab. I have used wax, impression material, cavit, IRM, uncured composite. They all had their drawbacks for me.

I was reading the other day about just this thing and got a great tip that I wanted to share on how to deal with this exact issue. The answer? Plumbers tape. You heard me ... plumbers tape.

I have no use for plumber’s tape at home since I can't fix anything. We have a rule in my house: don't ask me to fix anything in the house unless you want the final product to look like a tooth!  

I know nothing about fixing things, especially plumbing, but I do use the plumbers tape for anterior composites all the time as a separating medium from the adjacent contact. I tried it out today on a case and it was perfect. Plumbers tape is almost rubbery. You can condense it into the opening of the abutment or the transfer coping and take your impression. When you are done, just take an explorer and pull it right out. No mess, nothing getting stuck in the access opening or over the screw. It’s fantastic. Give it a try.

One of the questions I get asked frequently is what’s the best instrument to remove the sprue from the restoration when it comes out of the milling chamber?

Well, there are a lot of good ways, but I thought I’d share something that we started using at the Center recently for the CEREC courses. The Alpen polishers from Coltene Whaledent. I use the coarse wheel on a slow-speed straight hand piece at about medium speed to remove the sprue. These burs handle nicely and I would imagine this wheel would last a long time given that it will remove a sprue in just a few seconds.

Once you remove the sprue, you basically polish up the restoration prior to stain and glaze. I’ve included some product shots for reference. If anyone wants to try them, they’re available through your Patterson rep. Good product. I liked it.

I love the idea of partial coverage restorations:  Being conservative and less invasive!  But I hate seeing some of these restorations where there now is obvious decay in the interproximal area of the wall we did not reduce.  Eventhough we made every effort to check for caries at the intial placement, there are times where they go undetected and surface years later.  This is one of the few arguments against partial coverage.  What adjuncts do you use to make sure the tooth structure you leave behind is not compromised?

The year has come to an end, and it was touch and go for awhile. The normal week-before-Christmas cancelations didn’t come, but of course all the emergencies came out of the woodwork.  Five long days, from morning to night, it was bananas.

Broken teeth, people in from out of town, and the following week I am to be out of the office. The perfect storm that CEREC can help tremendously.

One particular case that stands out and makes me publicly thank (Sirona’s Manager of CEREC software) Mr. Ingo Zimmer was a broken crown I did a few years ago. The patient was back in town to visit her family. I got her to come in at 6:30 a.m. prior to my other patients, and proceeded to redo it. I proceeded to do the visit as normal. Give a block, apply Liquid Reference, take buccal bite and opposing, and in this case I took a pre-op even though I was planning on utilizing Biogeneric.

I took the pre-op because:

1. I was trying out a new workflow
2. I wanted to copy an old PFM with a fractured DB cusp
3. No real reason

I removed the old PFM and the recurrent decay that extended pretty far sub-G, rebuilt a core and refined prep. Nothing out of the ordinary, and things looked good, just took some time to get this completed. Rendered the proposal and looked from the buccal and saw my marginal ridges were way off. Then I looked at the clock and saw that the appointment time for my next patient was quickly approaching. In my sleep-deprived state, I messed up the buccal bite and didn’t pick it up.

What to do? Re-image buccal bite and possibly the prep and opposing? Guess at the occlusion and grind it in? But this would take time. Then it hit me I had the extra folder! Even though I was doing Biogeneric I have the flexibility in 4.0 to do so many things efficiently. I could edit restoration and turn it to Bio-copy if I wanted. In this case, I just overlaid the Bio-copy folder on the virtual model and used that to establish the occlusion. By taking 30 seconds to take the Bio-copy folder, I save a bunch of time in the long run due to my missing a good buccal bite.

So the answer is C. But I was real lucky that I did do the extra imaging. The extra folders help add flexibility to an already powerful system

Thank You, Mr. Zimmer.

One question I get very often from people is, "How do I design my preps for CEREC restorations?”  When I hear this question, my mind immediately goes back to dental school – how we are programmed to think a certain way... an onlay looks like this, a crown looks like this, etc...

I completely understand this line of thinking, because I was once there myself. Every full-coverage crown was similar in design. Maybe you prepped a deep chamfer or maybe a shoulder with a bevel. Whatever your design of choice, you most likely went into that procedure with a plan in place on how you were going to prep that tooth.

One of the great pleasures of practicing same day CAD/CAM dentistry is throwing that philosophy completely out the window. CEREC allows me to be creative on how I approach a situation. I never have a set prep in mind.

I now approach a tooth in a much different way. I start by removing the restorative material and any existing decay, and then I just let the prep "come to me." Every prep is different, just like every tooth is different. Not only can this often be better and more conservative for the patient, but this creative mindset is also much more fun for a dentist.

Take a look at this case and visualize how you would prep this case. There are no right or wrong answers, and many dentist would prep it differently. I will show you how I prepped it. How would you prep it?  Feel free to join in on our discussion on this topic here: http://www.cerecdoctors.com/discussion-boards/view/id/8179/page/1

My two good buddies from dental school are cerec users now.  Dr. Raj Anand was actually the very first office in the US to have Cerec 3D installed the very first day it was released some 8 years ago, and they have been cranking ever since.  My other good friend Dr, Joseph Nguyen, aka, a to the k, Sundance Kid, just had their cerec delivered.  He has been watching all the videos on this site and I was elated to get this text from him today:

"Did my 1st Cerec Yesterday.  Was awesome and your site had me totally prepared me.  Restoration flew in there with minical occl adjustments.  So much better than traditional lab."

I can't emphasize how excited I am that they are on board.  From our class of 1998, there are now a good number of us in the digital realm.  Dr, Brad Drosh, Dr. Eric Martin, Dr. Veena Bhat, and Raj's wife Nisha is also using a cerec in her office.  Ask me about Nisha when you see me next time in person and I'll tell you how she discourage my wife from dating me  :)

Both Raj and Joe played the role of Bridesmaids for me back in a dental school halloween party.  I have worn a dress twice in my life, both at halloweem, and I have to admit it was the most comfortable outfit I have ever put on.

I had an interesting observation today when milling out some units for an experiment Im doing on Adhesive Gap - you know the paramters for onlays that so many people understand so clearly (Insert sarcasm here).   In milling out some restorations out of the LAVA Ultimate material for this test, I noticed something interesting - how thin the material will mill.

Let me explain - when you mill out a CEREC restoration, there are some left over fins on the block itself. sometimes the fins stay, sometimes they break- we really dont give it another thought in that the amount of remaining porcelain is somewhat errratic.  

So I milled the first restoration and lo and behold there were some fins left over on the block. It was interesting to see how thin the remaining material was as you can see from the photo below:

Yes- as a reference I put a dime behind the restoration to give you an idea of size.  The material mills very thin:

What wasnt interesting that only one restoration had the left over fins.  What was interesting was that all 5 blocks that I milled had the exact same pattern. Even if you are milling the same file, other materials will break off and sometimes you have a fin left over, sometimes you dont. In this case all 5 blocks had the same effect.

If the long term luster and shine holds up on this LAVA Ultimate material, I think we have a real winner here. Initial impressions are very promising.

I get lots of questions over the years about CEREC. I honestly think that one of the biggest misconceptions that we have had to deal with is that the margins are not good. The margins are what makes me love doing CEREC. 3M has come out with a new material called Lava Ultimate. It is a nanoceramic, and may be the nicest milling material of all the materials we have available to us. I have been really impressed by it.

I can show post-op photos all day of what a restoration looks like, but I think images of a restoration right out of the milling unit with no resin in there speak volumes. Here is a recent MOL onlay I did on a second molar. I'm pretty darn happy with these margins out of the miller.

I have been using this material on what I was using standard resins for before. For me, it beats placing a ring and band and wedge and praying I have a good contact.

If you do a lot of resins in your practice, you know how exhausting a quad of resins can be. One of these days, try doing it with your CEREC and Lava Ultimate. I've been really happy with my results.

In the 4.02 software update, one little feature that we now have is the ability to ­­­track how many times the burs have been used. In the Mill Preview, in the Restoration step menu, prior to hitting Start to begin the milling, you will see (as indicated by the arrow) the number of mills each bur has. This allows you to keep track of the bur usage and change it out regularly.

The question that arises is how many times should you use a bur before you swap it out? There has been a lot of research done on this internally by Sirona, and the consensus is that after about 20 mills, you should swap out your burs. There is a tremendous amount of wear after 20 mills, and not only does it affect the time it takes to mill (your indicator says six minutes to mill but it actually takes eight – this is a sign of worn burs) but you can have increased chipping at the margins. Worn-out burs will tend to chip your restorations and leave a slightly rougher surface if you push the limits with them milling. So once you hit 20 mills, change out your burs.  If you are at 18 mills and one bur goes bad, change them both out.  Keep things consistent and simple.

Cement sepsis is now thought to be a leading cause of peri implantitis. It will lead to bone loss around an implant and ultimately to total implant failure. This iatrogenic problem is easily preventable. Avoiding intraoral cementation is the key. This is simply accomplished by fabricating screw-retained implant crowns wherever possible.

Fabricating cement-retained implant crowns with CEREC is simple and predictable. Fabricating screw-retained implant crowns is also very easy and makes the placement visit fast and enjoyable. This is a procedure I tend to do in two visits, which makes this totally stress-free. It's a total win/win for both the doctor and the patient.

Simply, I take a fixture-level impression and images of the opposing arch and buccal bite, pour up a soft tissue, place the appropriate abutment and adjust it as needed. I image the abutment and design the crown as usual. I make the restoration transparent, and using the Form Minus tool, I make a hole directly over the screw hole in the abutment. I mill the crown, finish the screw hole by hand and complete the crown. Then I cement the crown to the abutment and thoroughly clean up the extruded cement.

At the place visit, I just unscrew the healing cap and screw in the restoration and abutment as one unit. Now, surely there are more nuances to this technique than I have listed. After a few, you will find so many shortcuts to make your life easier. Challenge yourself to do this and you will be totally convinced that this is a fantastic way to do dentistry. Most importantly, you will remove the risk of the dreaded cement sepsis.

There are multiple threads on the cerecdoctors.com discussion boards to help you through the learning process, as well as videos to visually walk you through. CEREC and implants are a match made in heaven. We have the accuracy and the materials to make fantastic restorations. Do it and make dentistry fun.

One more thing to mention: Using the InLab software and fabricating a custom abutment will also help to avoid cement sepsis. The custom abutment will raise the cement margin to be at or just slightly below the gingival level. The crown is then cemented, and the extruded cement is easily cleaned up. Both ways work well. Do what you feel comfortable with.