|Michael C. DiTolla, DDS|
Our editor-in-chief, Dr. Damon Adams, interviews Dr. Michael DiTolla, a much sought-after lecturer now serving as the director of clinical affairs for Sirona Dental and the director of SIROWORLD, Sirona’s official community for owners and fans of their digital technologies.
You recently underwent a pretty big change in your career; in fact, it seems like you almost went 180°. Can you talk about that?
Dr. DiTolla: You are correct, Damon. I recently left Glidewell Laboratories where I was the director of clinical education to become the director of clinical affairs for Sirona. And I can see why those 2 jobs would seem like complete opposites: one is inside a dental lab that fabricates restorations for clinicians that are seated about 2 weeks after the preparation appointment, and the other is working for the company that has pioneered and championed single-visit dentistry utilizing chairside CAD/CAM. But at Glidewell, we embraced CAD/CAM wholeheartedly and, in that respect, we shared Sirona’s vision. It didn’t take us long to realize that CAD/CAM manufacturing allowed us to achieve a consistency that we had never seen when all our restorations were handmade by hundreds of different technicians. As it turns out, one of the most common complaints that large dental labs receive relates to a lack of consistency from case to case; this leads to frustration for the dentist. CAD/CAM changed that for the laboratories by having crown designs come from a software library, with defined parameters to ensure that the die spacer, occlusal clearance, and contact pressure would always be the same. Initially, at Glidewell, we were using 13 Sirona MCXL mills to fabricate our lithium disilicate crowns (IPS e.max CAD [Ivoclar Vivadent]), but we would end up having to switch to using IPS e.max Press because we couldn’t get our dentists to prepare proper chamfer margins to prevent chipping at the margins when milled.
Michael, are you saying that the lab team had to change the way crowns were being made because the doctors were not providing a proper 360° chamfer margin?
Dr. DiTolla: Exactly! And I will share with you how I learned to prep correctly a bit later. I began to notice that the only dentists who were preparing e.max crowns correctly on a routine basis were the clinicians who were sending us digital impressions through the Sirona Connect portal. Dentists who use chairside CAD/CAM technology learn to cut and evaluate their preparations when designing and milling their own crowns. They don’t have to ruin too many $30 ceramic blocks to realize that they need a good chamfer rather than a featheredge margin. Being your own lab technician forces you to improve your preps and impressions, because you can no longer simply let your lab team deal with it. It became clear that the point of chairside CAD/CAM is not that dentists can make more aesthetic crowns than their lab technicians; it’s that they can make better crowns simply because they are single-visit crowns that don’t require a temporary and, therefore, almost eliminate the need to adjust and or have to remake these crowns.
|The Teneo Treatment Center integrates imaging, intraoral scanning, and implant and endodontic handpieces to create the Sirona Ultimate Office.|
|The Galileos Comfort Plus cone beam offers patient-friendly workflow by allowing CEREC dentists to mill their own surgical guides in order to precisely place and restore implants in a single-visit.|
In your experience, is it your opinion that laboratory owners felt threatened by the idea of dentists producing their own restorations in their own office?
Dr. DiTolla: The feeling at the lab was, now that we had proven to ourselves that this CAD/CAM technology really works, it was just a matter of time until the dentists learned this too. So the lab made the decision to build its own chairside CAD/CAM unit with an intraoral scanner and a mill. For any dentist who remains unconvinced that chairside CAD/CAM crowns are an inevitable future, the fact that the largest dental lab in the world developed its own system should put that to rest. You don’t see digital companies like Sirona opening dental labs just in case 2-appointment dentistry wins out in the long run. When you consider that 80% of the crowns done in the United States are for posterior teeth, the majority of these crowns could easily be fabricated with chairside CAD/CAM. Dental labs will always exist for cases where there is a lot of artistry needed, such as veneers, anterior crowns, and smile makeovers. They will function much like specialists in dentistry do. For example, most general practitioners will take care of the easier and straightforward endodontic procedures in their own practices. However, when it comes time to do a more difficult molar, or perhaps an apicoectomy, most will send those to their endodontist.
Considering that the majority of crowns that are placed in the United States today still use this 2-week turnaround time, is it actually a bigger challenge to convince the dentists that this is a better way to do dentistry than it is to convince patients?
Dr. DiTolla: Definitely! When you ask patients whether they would prefer their crown to be done in either one or 2 appointments, they look at you a little confused, wondering why you would ask this trick question. Of course they would always rather see us for one visit! When I speak to doctors, I always try to shift their thinking by presenting a scenario where we take a typically single-visit procedure and propose we do it in 2 visits—a Class II posterior composite is a good example. On the first visit, you would remove the old amalgam, any remaining decay, and place a temporary filling. Two weeks later the patient would come back, and you would re-anesthetize, remove the temporary filling, place a sectional matrix, and then etch, bond, place, and cure the composite. If you propose that workflow to dentists, they will tell you it’s ridiculous. Why would you leave a leaky temporary filling in the tooth for 2 weeks? Why would you subject the patient to a second injection and a second appointment, which also happens to remove most of the profit from that procedure? In the real world, composite is placed on that first visit because it’s the right thing to do for the tooth, the patient, and the practice. Today I see crowns the same way, and have no doubt that one day we will look back on temporary crowns as a necessary evil.
|Figure 1. Tooth No. 9 is going to be prepared for a lithium disilicate (IPS e.max [Ivoclar Vivadent]) using depth cuts that respect the 1.0-mm minimum material thickness recommended by the manufacturer for this material. (This same technique could be utilized for a solid zirconia crown with appropriate size burs for the material.)||Figure 2. The first step in the Reverse Preparation Technique is to use a 56 carbide bur to break the proximal contacts. Then, the first retraction cord is placed, determining the location of the gingival margin.|
|Figure 3. A size 00 Ultrapak plain cord (Ultradent Products) is the first cord packed. (Note: It is not soaked in any medicament.) The cord is flossed into place on the mesial and distal, and the 2 loose ends are packed flush to each other.||Figure 4. Once the first cord has vertically retracted the tissue about 0.5 mm, the gingival margin is prepped. This technique is called the Reverse Prep Technique because the gingival margin is prepped first, using an 801-021 bur to cut a perfect half-circle into the gingival third.|
|Figure 5. This gingival depth cut helps ensure that an aesthetic crown results, as many anterior crowns look unnatural due to under reduction in the gingival third. There is no easier way to prep an ideal margin.||Figure 6. Since the tooth is being restored to its original length, two 1.5-mm depth cuts are made in the incisal edge. Under-reduction of incisal edges causes crowns to look bulky and to end up too protrusive.|
Can you elaborate on temporary crowns being a “necessary evil”?
Dr. DiTolla: Of course. One of the most frustrating things in the lab is how, when a crown leaves the lab, the occlusion is perfect on the articulated models 95% of the time. However, when you look at the dentist feedback, nearly half of the dentists say that the occlusion was high on the crown. It became clear that the discrepancy was the influence of the temporary crown. More specifically, it was caused by the temporary being in place for 2 weeks, a number that has no scientific or clinical basis. Two weeks is simply the only option most laboratories give their dentists. Since I was practicing dentistry in the lab, it was easy for me to have crowns fabricated the next day and to cement them on the third day. I noticed that the amount of occlusal adjustment I had to do on a 3-day crown versus a 14-day crown dropped dramatically. Every dentist knows that the longer a temporary crown stays in place, the odds of the permanent crown fitting plummet dramatically. For example, if a patient goes away for 6 months with a temporary, we know that we may have to re-impress the prep and start over. The longer a temporary remains in place, the worse the fit of the permanent crown. Conversely, the shorter the period of time the temporary stays on, the better the fit of the permanent crown. In my opinion and clinical experience, the best case scenario is no temporary crown at all…single-visit dentistry!
Is it the actual composition of the temporary material itself that sets us up for having to do too many adjustments or remakes at the seat appointment, or do you think it is something else about the temporary?
Dr. DiTolla: Actually, I believe that the issue with the temporary crown is as much about operator error as it is with the material itself. In an attempt to make the temp as smooth as possible so it won’t bother the patient, many well-intended dental assistants inadvertently polish away the occlusal contacts that the temp should have with the opposing tooth. At one point, I decided to check my assistant’s temps to see if that was why I was having to adjust the occlusion a lot when doing 2-week dentistry. Just before she dismissed each patient, I checked the temp with a piece of articulating paper to see if there was a centric stop, and 80% of the time it was not there. I’m convinced it’s a chronic issue that is responsible for the super-eruption that takes place during the 2-week turnaround time that leads to the need for excessive occlusal adjustment at the seat appointment.
I have heard you begin your lectures by describing yourself as an average dentist and then telling a story to prove that you aren’t making it up. Do you mind sharing that story?
Dr. DiTolla: Not at all, Damon. It was my second year of dental school, and our first big clinical course was operative dentistry. At the University of the Pacific, the operative dentistry department had 9 instructors, 8 of whom were men, with a combined age of about 950 years. And, there was one female instructor who was 25 years old and gorgeous. I immediately had a crush on her, and I would have her check all of my preps just so I could spend a little more time staring into her beautiful blue eyes. One day, while I was on the clinic floor doing some paperwork, she came over and asked me what I was doing that weekend. I had wanted to ask her on a date, but I assumed I would be kicked out of school for doing that, but here she was asking me about my weekend plans! As calmly and as coolly as I could, I told her I was free and asked her what she had in mind. That’s when she told me there was a remedial operative clinic at the school that Saturday. I didn’t realize what she was getting at, and asked her if she needed help passing out the typodonts or the teeth. That’s when she informed me that I was going to be taking the remedial class! That should have been my first clue that I was going to need a little more help than the average student. It wouldn’t be until I started practicing at Glidewell, where everything I did was filmed and blown up onto two 42-inch monitors, that I would develop a technique that would allow me to prep teeth as well as my clinical mentors.
|Figure 7. With the depth cut bur perpendicular to the facial surface of the tooth, at the junction of the incisal and middle thirds, a 1.0-mm axial depth cut is placed. This depth cut should be just gingival to the incisal edge depth cuts.||Figure 8. Next, the depth cuts are all finished, allowing the rest of the prep to be done very efficiently with no guesswork related to reduction. Once the depth cuts are gone, the prep is essentially completed.|
|Figure 9. After some smoothing, it is time to place the top cord (2E Ultrapak cord [Ultradent Products]). While the first cord that was placed retracts the tissue gingivally for margin placement, the second cord provides all the lateral retraction to get a great impression. (Note: A one-cord technique will not accomplish this.)||Figure 10. This No. 2E cord cannot be used in all clinical situations; it is simply too large for many mandibular anterior teeth or upper bicuspids that may have minimal attached tissue. A smaller top cord, such as a size one cord, may be used in these cases. (Note: Some retraction is always better than none.)|
|Figure 11. This photo shows the top cord in place with just a small tail protruding on the lingual for easier removal. The gingival margin of the preparation is uniform and smooth all around the preparation; due to the use of the round bur early in the procedure with all the hard-tissue landmarks still in place.|
Is the technique you are referring to the Reverse Preparation Technique that I have seen you demonstrate online?
Dr. DiTolla: Yes! The Reverse Prep Technique was not my attempting to be an innovator, it was my looking for a way to keep from embarrassing myself at Glidewell when prepping and impressing teeth in front of the lab team. I call it the Reverse Prep Technique because it is pretty much backwards from how I was taught to prep teeth in dental school. I prep the margin first rather than last, and use a special bur (a round diamond bur—an 801-018) that makes it incredibly simple to do with better results than I was ever able to obtain before. I am convinced that the method most dental schools use to teach students to prepare teeth for crown and bridge is fantastic for the top 10% to 15% of the students in the class. Of course, these are the same students who could probably learn to prep teeth with their feet if necessary; they can make almost any technique work for them. But, for the majority of the class, we need to give them a technique that doesn’t require one to be an artist to end up with a beautiful, properly reduced prep. This isn’t the Olympics, where you get a higher score if the degree of difficulty is higher, so I came up with a technique for myself that was like the paint-by-numbers kits from childhood. It is essentially “prep-by-numbers,” where you follow a checklist with a certain set of burs that ensure you get adequate reduction through the use of self-limiting depth cutting burs (Figures 1 to 11).
Rather than prepping a tooth like a free-handed sculpture—where you start with a huge cylinder of marble and end up with something like Michelangelo’s David from it—your technique is based on depth cuts?
Dr. DiTolla: The funny thing is, when you place the appropriate depth cuts in the correct places on the tooth and then connect them, you end up with a prep that looks exactly like a prep from a highly skilled dentist who can do it without the use of these specific burs. It used to bother me that I needed a checklist to accomplish the same result that an artistic dentist could accomplish freehand, but I stopped caring about that a long time ago. I don’t think the lab team or the patient cares about how you get to a great prep. Furthermore, I fly more than 150,000 miles a year lecturing, and every time I get on a plane, I see the 2 pilots who often appear to have almost 100 years of flying experience between them using a checklist prior to takeoff, even though I’m pretty sure they have it memorized by now. Well, if a checklist is good enough for professional airline pilots, then it’s good enough for me for my preps! I’m done feeling artistically insulted by needing to use a checklist, because no one cares about the process; they only care about the results.
Digital impressions aren’t being adopted as quickly as many in the industry had expected. Why do you think that is?
Dr. DiTolla: First of all, if any dentist, young or old, wants to improve his or her preparation skills, I always recommend that these dentists purchase a digital impression unit and use it regularly. There is no other way to jump start one’s skills as quickly and effectively. If I were teaching at a dental school, I would want the students to use digital impressions for their first 20 crowns. But I think the biggest reason they aren’t seeing widespread adoption is that digital impressions were never really designed to be used as a stand-alone system; they only existed because they were necessary to accomplish single-visit dentistry. Sirona never introduced a stand-alone digital impression system until a few other companies released stand-alone systems; I think they understood that it would be hard for digital impressions to compete with silicone impressions if you weren’t doing single-visit dentistry. I don’t even like calling these systems “digital impression” systems because I think it invites dentists to compare them head-to-head with vinyl polysiloxane (VPS) and polyether impressions, both of which are accurate and affordable…when handled correctly. It’s no wonder doctors look at digital impressions and are confused as to why they should invest in this technology when VPS and polyether impressions are clearly “not broken.” I would rather call them digital scanning or digital enhancement systems, because the truth is that they do 6 other things that no other technology can do. In fact, they make loupes look silly with their ability to blow up a prep on a 27-in computer monitor. In my opinion, out of the 6 amazing things these digital systems can do, the least impressive is their ability to make an impression. But these systems are about so much more than that—that list of the 6 other things they do is pretty revolutionary in my opinion.
Dr. Adams: Michael, I want to to thank you for taking the time out of your extremely busy schedule to give our readers some clinically relevant insights based upon your clinical experiences and work with the laboratory team at Glidewell Laboratories, and on your work with Sirona. We wish you the all the best for continued success!
Dr. DiTolla was in private practice for 15 years before becoming director of clinical education for Glidewell Laboratories. In 2015, he became director of clinical affairs for Sirona Dental. He is also director of SIROWORLD, Sirona’s official community for owners and fans of their digital technologies. He lectured on behalf of Clinician’s Report, presenting their iconic “Dentistry Update” lectures from 2012 to 2015. In 2011, he received the “Most Effective Dentist Educator” award in a nationwide survey of dentists. He can be reached at firstname.lastname@example.org or through his website at drditolla.com. Listen to his podcast Accidental Geniuses at the website accidentalgeniusespod.com.
Disclosure: Dr. DiTolla is the director of clinical affairs for Sirona Dental.