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I started to hum the song, "Should I Stay or Should I Go" when I was thinking about this blog topic. I blogged last week about being able to salvage a case on a patient who had a broken veneer and came in to my office to fix it. As I was writing the blog I had a patient call that I did a case on about 18 months ago. This is an elderly woman who had a tooth that had a very guarded prognosis. It was #7, it had large decay near the nerve and there was not much tooth structure left to bond to. There was a good amount of bone loss, but her daughter really wanted to save the tooth as long I could. I told them I'd try and do a build-up and crown and see what I could do. I did the case last year and all seemed well. I had seen her for a few recalls and it was holding up fine. They called last week and she broke it. When she came in, it appeared that there was a de-bond. The buildup I did was pristine. I decided that I'd find the old case on my CEREC machine and just mill it and see if the margins were ok. In about 10 minutes, I was able to take the crown out of the milling unit, try it in and have a perfect fit. I was so happy that I saved the case. It was a time-saver for me as well as for my patient. We were able to get her out of the office in less than 30 minutes, start to finish.

This story made me think about the question, "Should I have or should I throw?" Should I save all my old cases on my machine or should I delete them?  I have to say that this kind of thing has not happened to me often. When bonding, you normally would not be able to just re-mill. There would likely be some re-prepping to get the old porcelain and resin cement off the tooth.

From time to time, as in this case, you will get an ideal case to re-mill. Another instance of when this has happened to me over the years is with implant cases. I have had about three in the eight-plus years I've been doing CEREC break. This was mainly because I was using conventional porcelain blocks over the metal abutment. There was no choice early on in my CEREC career. The great thing was, when these restorations failed and the patient called me to tell me their crown broke, I was able to mill and characterize a new one by the time they came into the office that day and it fit perfectly over the metal abutment.

I do not feel that my machine is slowed down any by keeping the files. After a few years, I have saved them to an external drive just in case, so if they are removed from my machine, I still have them. If you ask me if you should save all your cases, I say, "If you save you'll avoid trouble, and if you throw there will be double."  Terrible Clash parody, I know, but save your cases. In my opinion the pros definitely outweigh any possible cons.

There are a lot of misconceptions, hyperbole and misunderstandings regarding the shortened cycle for e.max, and because this topic keeps coming up again and again, I thought it appropriate to dedicate another blog post to it.

I want to take this opportunity to review some facts, and let the folks make their own decisions regarding the shortened cycle and whether they want to use it or not in their practice. We as clinicians should always heed manufacturer instructions, however, sometimes it makes sense to read between the lines.

First - here is a blog post that I did a while back on this topic that addresses the strength issue:

I had the opportunity to be the opening keynote at a CEREC conference in Quebec, Canada. The event was amazing and it was absolutely brilliant how the entire Patterson Canada team came together to do this event. I've attached a brief video of Friday evening's festivities to give you a glimpse of how beautifully executed the symposium was. 

There were some great speakers at the event, one of them being Dr. Fasbinder who I've had the pleasure of knowing for years now. He is a researcher at the University of Michigan and one of the most knowledgeable people I know when it comes to CEREC materials. We started discussing one of my favorite topics: the shortened e.max cycle. 

Dr. Dennis Fasbinder presented some data on the fast fire. According to his data, you have a roughly 20% loss of strength with the fast fire. His data showed that at a 28-minute firing cycle, the strength was 476 mpa. At 19 minutes it was 456. At 12:40 it was 378 and Empress CAD glazed 177.

When Dr. Paul Child originally did the study, he found no loss in strength. So best case scenario you have no change in strength; worst case scenario you lose 20%.

Dr. Fasbinder also stated that in his numerous ongoing clinical studies, the worst success rate with ALL materials is 96%.

He and I were at dinner and we had a great discussion on how strong is strong enough. In other words, if I have a weaker material (VITA, Empress) and the lowest success rate with those materials is 96% in his studies, then isn't a supposedly "weaker" e.max with the shortened cycle at 378 mpa strong enough?

My contention remains that for routine work, the roughly 8-18 minutes saved in the fast fire cycle is well worth the loss of strength (even if its 20%). That 378 is still more than twice as strong as anything else.

I've asked Dennis to come on the site and discuss this as he feels that there are enough users here to collect some real world data to see if the 378 in his data is a big deal or not.

To me, loss of strength is not a reason to not use the shortened cycle at all. The restorations are "strong enough" in most routine applications. Dr. Russell Giordano has done a study similar to Dr. Paul Child’s study, where he found no loss of strength in e.max. so with three independent studies, two found no loss of strength, one found approximately 17 percent loss of strength from the 19 minute to the 12:40 cycle. So if you average the three studies, you have about a 5 percent loss of strength when you go to the shortened cycle.

The next area of contention is the incomplete conversion of lithium metasilicate to lithium disilicate when you fire the restorations. This conversion of the meta to the di is what causes the restorations to change color as well as gain its final strength. One may feel that if there is incomplete conversion in the shortened cycle. This may be interpreted as a problem.

However, let’s look at this conversion and look at the facts:

1. Yes there is incomplete conversion of the meta silicate in the 12:40 cycle. However, there is incomplete conversion at the 19-minute and 26-minute cycles as well. In all the cycles, some level of meta silicate remains in the restoration.
2. The only side-effect of the incomplete conversion appears to be a slight color modification on e.max LT blocks – as reported, the restorations look a bit "bright" – there is no effect on color on the e.max HT blocks.
3. Even with the incomplete conversion, there appears to be virtually no loss of strength (5 percent, as stated above)
4. Lithium metasilicate causes no damaging effects to the body – meaning it’s not as if your patients are going to develop any abnormal symptoms from metasilicate in their restorations.

So if you look at the facts, other than a slight color issue with LT blocks and a slight loss of strength, using the 12:40 cycle seems to have no ill effects. As a clinician, what you have to decide is when the seven to eight minutes of time savings is enough for you to use the shorter cycle. If time is not an issue, by all means use the 19 minute. But clinically I’ve used the 12:40 for several years with no issue whatsoever.

Does this mean that for the future we are completely safe?  Don’t know. Until more data comes out, we have to approach with caution, and as I stated above, we should always follow manufacturer recommendations. But you also have to use your clinical judgment.

I leave you with one thought – Let’s assume for a second that you do lose significant strength at the 12:40 cycle. A weaker restoration seems to be the big worry here, that the crowns will break prematurely. My question then is, why are you still using Empress and Vita? An e.max at 12:40 is still twice as strong as anything else. And as Dr. Fasbinder stated, the worst-performing material in his studies still had a 96 percent success rate.

My two cents: I have used this cycle without fear for several years now, thanks to Dr. Child and Dr. Giordano's research. The time savings to me are significant enough where in a busy practice I would not hesitate to use the 12:40 cycle. I know there are speakers and trainers out there proclaiming the end of the world if you use this shortened cycle. I just wonder if they will be as willing to admit they were wrong as loudly if and when Ivoclar ever does change the times officially.

As the end of the year comes, we get all kinds of emergencies. I always find that the broken front tooth or front crown seems so much more prevalent than other times of the year.

Here is a case that is a few years old, where the patient was going out of town for the holidays and broke an existing veneer. He had the broken veneer and brought it in with him.

I was able to bond it lightly back onto the tooth and then take some images of it with my CEREC machine that I used to copy exactly what was in his mouth. I then prepped the tooth a bit to clean it up, and took a new image to make a new veneer. I used a Vita block to match his existing porcelain and with just a bit of glaze I was able to get a great match and send him on his way.

This is the kind of service that is not possible without having the ability to mill in your office.

I took a three-year post-op image of the tooth. The patient could not be happier with the result. He was so amazed by the technology and service provided by our office. A nice way to wish a patient happy holiday!

Being able to design multiple units simultaneously is probably the greatest feature of the 4.0 software. Recently there was a discussion regarding ways to approach a case where the doctor was treating both teeth numbers 3 and 14. Basically, there are three ways to approach a case like this. The options are interesting.

- Image the full arch of the pre-operative situation. Image the full opposing arch. Image the full arch after the teeth are prepped. Image the buccal bite. Wow, that's a huge amount of work which will require a great deal of effort for both the doctor and the patient. Additionally, it will tax the resources of the machine. There are many issues that can occur to make doing it this way quite challenging.

- Image the right side pre-operative situation and then skip to the left side and image that. Go to the image catalog and ignore the images of the left side. Do the same for the opposing and ignore the left side. Do the same after both teeth are prepped and once again ignore the images the left side. Finally, take a buccal bite image of both sides and ignore the left side. Sure, you can see where this is going. Design the right side and send to the mill. Reopen the case and re-activate the ignored images and ignore all of the images for the right side. Move forward designing from this point. That's some pretty advanced image manipulation and some trickery. It's good practice for multiple adjacent units, but you can get in trouble very fast. The bottom line here is that you get slowed down at the cementation step because you need to isolate and cement separately.

- Finally, you can treat each tooth as an entirely separate case. In one instance of the program, image the right side completely and in another instance image the left. Once you finish designing one side, send it to the mill and design the opposite side. This is simple, reliable and fast. It's not glamorous and surely doesn't take advantage of the best part of 4.0, but it works well.

I am sure there are some who will use each way and feel that that's the best. There is no right or wrong here. As we all get used to the 4.0 software, just keep the basics in mind. That includes thinking through all of your options ahead of time and choosing the one that you feel most comfortable with. The end result will be the same for all options. It's the means to the end that has the ability to stress us out and change our day negatively.

Proper preplanning is the key to happiness.

On one of the recent discussion threads, there was a question about sandblasting the internal of e.max restorations and whether or not that may cause the restoration to fail prematurely.

After coming out of the oven, there is sometimes residue left over from the firing process. What’s the best way to remove this residue? Can you sandblast the internal of an e.max to clean out the debris?

Any time you alter the internal of a piece of porcelain, you risk microfractures that can spread.

Microfractures start out small but over time can spread and cause eventual failure of the restoration. If I take a handpiece to the outer surface of an e.max, chances are that the glaze or polishing the surface will remove the defects that I have created, and keep them from spreading.

On the internal however, because we don’t polish or glaze, there is a chance that the defect will spread. Whether that defect is created by a handpiece or by a sandblaster is not important – what is important is that we avoid causing any unnecessary stress to the porcelain itself. With weaker porcelains the stress can spread more quickly. With e.max – because of its strength, it typically takes longer for the stress to appear.

The bottom line: To avoid these microfractures, avoid altering the internal of the restoration at any cost. If you do have debris, try removing it with a tooth brush. If you must use some form of a sandblasting device, limit it to a small microetcher with the 25 microns of powder. Do not under any circumstances use an air abrader that has large particle size or has high pressure.

By minimizing any contact with the internal of the restoration, we minimize the potential for microfractures and the eventual failure of the restoration.

There is a great discussion on this topic happening here:

http://www.cerecdoctors.com/discussion-boards/view/id/8010

As the end of the year quickly approaches, I get questions from other doctors about what things they should invest in for themselves and their practices. I have a definitive Top 6 list of things that I cannot practice without. (I made it six because I really couldn't not talk about each of these six items.) I also have 1 BIG THING on my wish list that I hope to get soon.

My Top 6 list of THINGS THAT EVERY DENTIST SHOULD HAVE:

6.) A DIODE LASER

I love my diode. I use it every day when doing CEREC restorations, when doing cosmetic cases were I'm adjusting tissue height, when doing gingival composite restorations and so many other areas. Some use it for perio. I use it to remove the discomfort patients receive from pathos ulcers. The prices on this technology has dropped dramatically over the last few years and now is a great time to pick one up for your practice

5.) CEREC

I had to include this, of course. I'm sure that many would think this would be No. 1 on my list. Don't get me wrong, I love this technology. The reason it is No. 4 is because I don't use it on every patient every day. It has a great ROI, my patients love it, my staff loves it, it makes me a better dentist and it has re- energized my love for this profession.

4.) ISOLITE

I did a recent blog on the importance of this piece of equipment. I cannot stress strongly enough how important isolation is for the majority of the procedures we do. The reason this is higher on my list than CEREC is because I use it way more on a day-to-day basis. If you don't have one in your practice, get one. You will not regret it!

3.) DIGITAL X RAYS

I could not ever imagine going back to film. Getting my info immediately and being able to see it blown up on my chairside mounted monitor is fantastic. I don't miss processors, chemicals, mounting films and the time it took to get the images. So easy to share info with patients and use it as a teaching tool.

2.) INTRA-ORAL CAMERA OR SLR CAMERA

I think getting a digital camera and taking photos of every patient that comes into your practice is of the utmost importance. A picture tells patients 1,000 words. When you can show an image of a situation in your patient’s mouth and ask the question," Do you see that?" and wait for their answer, they will tell you what is going on or at least ask you about it. I use it for insurance reimbursement, before-and-after images, Invisalign cases and just a baseline when new patients come in. I also use it when I see a suspect area that I want to send for a surgeon for evaluation or biopsy. It is an invaluable piece of equipment in our practice.

1.) LOUPES AND A PORTABLE HEAD LIGHT

I will cancel patients if my loupes break. I have actually done it. I cannot imagine ever prepping a tooth without magnification. About five years ago I added a mounted portable light to my loupes and I could not believe how much more I could see. I have not turned on my overhead light in years. You have a flood of light wherever your eyes look. This combination of magnification has taken my dental skills to a much higher level. There are lots of good options for both loupes and lights. Get a 30-day trial and use them. An absolute must have for EVERY dentist, in my humble opinion.

Now for my wish list, I have one item on my brain.....GALILEOS. That will for sure be my next big present to me and my patients. I hope the next time I put out Must-Have list, I can give my feedback on what GALILEOS has done for me, my practice and my patients.

So, the neat thing in 4.0 is the ability to do multiple restorations. Not only multiple restorations on the same arch, but on opposing arches as well. Beta tester extraordinaire Dr. Bobby Chaggar ran some tests on which order you should propose the restorations.

Which is better?

Doing the mandibular first or the maxillary?

What about when you are doing two restorations in the same arch? Obviously you can propose both together, but sometimes, time-wise, it’s better to do one at a time to take advantage of the time savings.

Regardless – during beta testing, what Bobby found out was that if you are proposing two restorations together, propose the distal before the mesial and propose the mandibular before the maxillary. This will give you nice results and it will result in proposals that require the least amount of work. There are some great videos on this on the site that you can check out that go into the details of what happens when you don’t propose things in the proper order. Review them, and you will learn a ton about how the software functions:

Quadrant Rules in 4.0

Proposing Two Restorations – Mesial or Distal First?

One of the things I really love about CEREC and cerecdoctors.com is that rarely a day passes where I don't learn something new. I think it's great when a topic or process that is unclear to me suddenly just makes total sense. Sometimes it's the repetition of hearing it several times, but usually it's just the way the topic is presented or discussed that just hits a chord.

Recently there was a discussion board thread that did such a thing. Not an earth-shattering subject, maybe not even a topic that will change my technique at all. It is more like a clarity or understanding that just drives a point home. The discussion was about design techniques and when to use them. It was more of a poll with people chiming in with their opinions.

The general consensus was:

BioCopy for special posterior situations, like crowning a tooth that is a partial denture abutment or resides under an orthodontic aligner or night guard. Anteriorly, it is the design method of choice when we want to copy teeth with favorable shape and alignment, mocked-up situations or temporaries made to ideal specifications. That's generally the way it's been for a long time. Nothing really new here.

Biogeneric Individual for most posterior applications not listed above. That, hands down is what most are doing. Using BioCopy posteriorly was the way most did it years ago, but the Biogeneric process has gotten so good that most are now using it almost exclusively. Granted, there are exceptions to every rule, so use your clinical judgment and what you are most comfortable with. Using Biogeneric designs anteriorly can be done, but it can be a crap-shoot at times. For this we have other choices.

Biogeneric Reference is the best reason to avoid Biogeneric Individual in the anterior, and here is the thing that gave me clarity on the subject. Like I said, not-earth shattering, but makes sense for me. Use Biogeneric Reference anteriorly to copy the anatomy of a central or lateral. This will avoid the need for a mock-up to allow for Biocopy or the roll of the dice with Biogeneric Individual. Does NOT use Biogeneric Reference in the posterior to, say, copy a premolar when designing a molar. Sure it will work, but why use it when we have such a strong Biogeneric process? The exception might be when we have a lone molar or a bunch of blown-out adjacent teeth with limited, valuable data to base a proposal off of. Mostly however, I now think of Biogeneric Reference as an anterior design option that works great.

I may change my mind in the future, and that's ok. For now, that's what I took away from that thread and that is why I love what I do. The learning never ends and never gets old as long as you are open to accept it.

As I talk to docs all over the country, both CEREC users and non-CEREC users, I get lots of questions about the CEREC process. The two most common are about powdering and bonding. These are probably the two most technique sensitive parts of the CEREC process. This does not mean that either is difficult, but steps must be taken to make sure that both are done well.

The first question that I ask these doctors is, "What are you using for isolation?" Many times, the standard answers are cotton rolls and dry angles, and four-handed or even six-handed dentistry to keep saliva at bay. To me, this is the root of the problem.

When powdering, we have a few arch enemies: saliva, weeping tissue, cheeks and tongues. These things really tend to toss a monkey wrench into what we are doing, just as they do when taking conventional impressions. It is hard to have an assistant try and control that overly active tongue, that cheek and lip that seem to want to purse when we put anything inside the mouth, and the excessive salivation that occurs in many. 

These same issues also seem to rear their ugly heads when bonding. Some docs will tell me that they have the best chairside assistant ever and that they have no problem overcoming these barriers. I tell them that is great, but who is stopping that patient from breathing? Every time they exhale, there is moisture and likely a contaminated bond. This is why isolation is so important.

I know that when I mention the words “rubber dam” to doctors, they look at me as if I have spoken in an ancient language that they do not understand. I tend to get that look myself. I like to use the rubber dam on occasion, but also struggle with it for larger cases. I aspire to be like some of the CEREC docs out there who use it on every procedure (Andy and Russell, you know I'm referring to you!).

I have a list of things that I cannot practice without. One of those is the Isolite. This eliminates all the struggle of saliva, tongues, cheeks and respiration that we run into with every patient. I'm always amazed at how many people have not even heard of this device. It has been a practice-changer for me. This product hooks up to your high-speed suction and has disposable mouthpieces that keep away the cheek and tongue, and simultaneously suction the area. It allows you to work on upper and lower arches simultaneously. I use it for CEREC (even with full-arch impressions!), restorative, sealants, hygiene and sometimes even during extractions and implant placement. I cannot recommend this piece of equipment highly enough. You can get more info about it at isolitesystems.com. For those of you out there struggling with powdering and bonding, you can thank me later!

One of the first classes that we all had in dental school was Dental Anatomy. Granted, we like to forget those days, but as horrible as they were, what we learned was very important. The real problem with learning Dental Anatomy so early in our schooling was that we learned so many things and really didn't know what was truly important to remember and what wasn't.

I remember my first operative procedure. I knew ahead of time that it was a class 1 amalgam on tooth number 14. I studied up on the anatomy and spent probably 30 minutes carving the amalgam. The instructor sat down to check it and asked for the largest spoon excavator that I had and a wet cotton pledget in a college plier. He immediately scooped out all of my painstakingly placed anatomy and smoothed everything down with the cotton pledget. He never explained why, and I soon realized that most amalgams looked the same way. It was a lesson that made no sense and there was no reason for it.

Fast forward 25 years, and we as CEREC dentists now wear an extra hat. We are dentists and also lab technicians. It is up to us to know our dental anatomy cold and be able to place it virtually and manually. Sure, we stare at teeth all day long, but mostly what we see is that terrible-looking scooped-out amalgam. We need to make sure that we are up on our anatomy for each and every tooth.

Recently I began to take a greater interest in placing very accurate primary anatomy. It makes our restorations look better and provides a home or our stains, which then makes them look great. Grab your old anatomy book and take a look. It doesn't matter how old the book is, dental anatomy is unchanged. You might be surprised at some of the things that now, as seasoned dentists you see. You are able to cut to the chase and see what is most important.

I plan to make it even easier for you to brush up on things. I think it is so very important that I am in the process of making a series of videos on dental anatomy. After a review, I will show you my technique to place and refine correct anatomy virtually. It adds less than a minute of design time and really makes our restorations look great.

As soon as I have the first ready, I will post it for you. It's not the most riveting subject, but one that is very important to our daily practice of dentistry.