The answer to this question is “it depends.”
First it is important to define what is meant by the terms “Analog” and “Digital.” The terms have different meanings for different media such as music and photography. In the art world, analog art is defined as “any art where the material making the art is manipulated by hand, like paint. You can control any portion of it.1” Since Dentistry is half art and half science, I’m going to amend this definition for dentistry: Analog Dentistry is “any dental art or science where material is manipulated by hand.”
By contrast, the term “digital dentistry” can be defined as “any dental art or science where individual pieces of electronic information that cannot be further broken down are manipulated electronically.” In the case of photography, these pieces of information are known as “pixels.” Pixels are often manipulated electronically on a computer to produce a physical product. Technologies that can accomplish this feat by following computer instructions include milling, 2D printing and 3D printing.
In order to answer the question of whether analog dentistry or digital dentistry is better, it is important to understand that no matter how dentistry is made, the dentist is entirely responsible for the OUTCOME2. Technology is a tool; NOT an end in itself. In order to create an ideal outcome BOTH analog and digital techniques must satisfy the same basic principles of health and longevity that have been PROVEN.
Analog Dentistry came first, so the standards that were set with analog procedures must also apply to digital procedures. If full coverage restorative dentistry is truly going to advance, anything new that comes down the pike MUST be compared to the standard that came before. Sadly, this is NOT being done.
In fact, most young professionals have absolutely no idea where full coverage restorative dentistry came from and how it evolved. Dentistry’s forebears were able to accomplish feats that young professionals CANNOT match—either with analog techniques or digital techniques. Most young professionals also have no idea what basic principles allowed Dentistry’s forbears to have such phenomenal success with full coverage restorations. They look at crowns and bridges as “tooth coverings” and not as a form of “plastic surgery” that can alter the architecture to prevent disease such as recurrent decay and periodontal bone loss.
How sad that young professionals are experiencing problems with crowns and bridges that were actually solved in the 1930s. One such problem is loss of retention on crowns. Crowns and bridges are not supposed to fall out and require periodic recementing. If crowns and bridges can come out, they can leak and decay.
The prevailing philosophy of retention that only makes use of tooth structure ABOVE the gingiva is the problem. What is really important is tooth structure BELOW the gingiva—getting a good grip on the root surface with dentistry that fits properly. Very few practitioners make use of the entire root surface below the gingiva. If they did, ANY tooth structure above the gingiva would not be required in order to have phenomenal retention. Butt-joint restorations, which are quite common these days, are not designed to extend below the gingiva onto the root surface. These restorations include CEREC, all-ceramic crowns and zirconia restorations. As a result, these restorations do NOT rise to the standard set by gold and porcelain-to-metal restorations by the pioneers of full coverage restorative dentistry. The pioneers of full coverage restorative dentistry designed their restorations to grip the root surface below the gingiva for tremendous retention, so they did not have crowns and bridges routinely falling out. Their restorations also mimicked the design of the Mason Jar Cover, which is the best means of food preservation ever devised. This design virtually eliminates recurrent decay.
It may sound like I am a nostalgic luddite who does not like technology. Not true! Some new technology DOES compare to the standard set by the pioneers of full coverage restorative dentistry. Scanning and milling technologies have proven to be every bit as accurate and perhaps superior to the analog technologies of waxing, casting and soldering. The Strategy Milling company of Pittsburgh, PA is at the forefront of milling precious metals and I am amazed at the advancements Scott and Tom Mappin have made to the dental profession. [https://strategygoldmilling.com/]
Intraoral scanning is confined to registering tooth structure above the gingiva and has great applications for orthodontics, appliance therapy and implant stent design. It is not, however, suitable for crown and bridgework. No one has yet invented a technology that can scan the entire root surface of teeth below the gingiva. That being said, desktop scanning of analog models and dies has proven to be quite accurate. A combination of analog and digital technologies is a great way to get around the inability of intraoral scanners to register an impression of the entire root surface below the gingiva. In fact, combining digital and analog techniques to produce artwork is quite common in the art world.1
Today’s young professionals pride themselves on being able to digitally produce dentistry on the computer. Indeed, mastering CAD-CAM software and digital design is no small feat. But without an understanding of basic principles of health and longevity, the OUTCOME is not going to be ideal and a poor OUTCOME translates to a lower percentage of successful cases. Restorations must be designed to fit with precision, prevent recurrent decay, correct occlusal balance, promote muscular harmony, restore the integrity of the dental arch, restore an ideal plane of occlusion, minimize forces on the bone and roots and distribute the load evenly on weak teeth with stress-breaking mechanisms such as splinting.
Most dentists and dental technicians, however, do not seem to understand how to apply these basic requirements to their restorations. Let’s take one of these principles and examine it closely—the basic principle of minimizing forces on the bone and the roots in order to solidify and preserve the teeth. One way to reduce forces on the supporting structures is to design dentistry with narrower buccolingual diameters. In preparing a vital tooth, only 1.5 to 2mm of tooth structure can be removed without interfering with the pulp. Creating restorations that are thicker than the amount of tooth structure removed will apply greater forces to the bone and roots, resulting in a poor prognosis. By contrast, creating restorations with a thickness that is less than the amount of tooth structure removed will reduce the forces applied to the bone and roots. This strategy requires a great deal of diligence and attention to detail. I always measure my temporaries, castings and permanent restorations to ensure the most ideal OUTCOME and I want my laboratory technicians to do the same.
After I started working with dental laboratories in Arizona, I realized that most dental laboratories are overflowing with oversized dentistry. I tasked the first dental laboratory I worked with in Arizona with waxing and casting a simple 4-unit bridge on articulated models and dies that I made myself. I asked the technician to allow me to check the wax up before investment and casting. The technician made a big production out of creating this wax up, and it seemed to take him forever. I couldn’t understand why until I saw what he was doing.
First, the technician waxed the entire bridge to full contour (which was actually over-contoured in my opinion). Then he cut away the outer surface for porcelain. The wax understructure was easily 1.5 to 2.0 mm thick, when it should only be .5mm thick. If the porcelain was added to this cast understructure, the OUTCOME surely would have been a monstrosity. In the wrong patient periodontal problems would be the likely result. Most dentists do not know anything about laboratory work, so they are happy to accept whatever is sent by the dental laboratory.
I was dismissed from this laboratory after their casting machine broke and they decided not to fix it. I soon found out that that less and less laboratories were waxing and casting restorations, which are century-old technologies. So I turned my attention to scanning and milling—technologies that DO conform to the basic principles I believe in. I worked closed with the Strategy Milling Company, which is at the forefront of milling precious metals. I made analog models and dies that were converted to digital models in a desktop scanner.
Once digitized, digital technicians designed the restoration on the computer. To my horror and disbelief, the digital technicians proceeded to make the EXACT same mistake as their analog colleagues! They first designed the restoration to full contour on the computer (which was really over-contoured) and then did a digital cut-back for the porcelain. The result can be seen in the adjacent picture. The second molar milling is what was sent to me untouched. I ground the first molar milling so that it was .5mm thick. Notice that it is considerably smaller than the second molar. What a waste of precious metal!
My NY technician NEVER designed crowns and bridges in this manner. In “analog” fashion he used dipping wax to create a coping with a uniform thickness of .5mm. The dipping wax is a plastic-like wax that hugs the die closely. All that was needed to complete the wax up was the addition of inlay wax to form a lingual collar, interproximal struts and perhaps even out the occlusal surface. The wax up was completed in no time! And, what’s more–very little finishing was required after casting, so precious metal was not wasted.
But both analog and digital technicians justified their cutback approach by maintaining that my technique would result in unsupported porcelain that was likely to break. Seventy years of documented cases does not support their claim. Even if breakage was a major complication, wouldn’t it be better to have broken porcelain than periodontal problems and loss of teeth? Techniques are available to easily repair broken porcelain. Oversized dentistry, on the other hand, can lead to periodontal bone loss that cannot be fixed, and the doctor will have to deal with the consequences long after the technicians have been paid.
Today’s new dentists have very little knowledge of laboratory work, and they no longer are required do any laboratory work as part of their dental school curriculum. When I was in dental school, I had to do all of my own laboratory work, so I graduated with some idea of the concerns that dental technicians have in creating full coverage restorations. I continued to do laboratory work in dental practice for my entire career. To this day I still pour all my own models, make my own dies and ditch the margins. I want to make sure that the models are correct–that there is adequate room to make ideal restorations and that there is no guesswork as to where the margins should be.
I also create and hand carve my own temporaries. I use the temporaries as a blueprint to determine how I would like the finished case. I want to correct all the deformities and incorporate basic principles of ideal dentistry in my temporaries. I want patients to walk out better than when they walked in. Once I am satisfied with the temporary restoration, I measure it with an Iwansen Gauge to make sure it has the correct thickness before I take my final impressions. I have carved thousands of temporaries for my patients and for my father’s patients over the course of my career. Today I can carve teeth practically in my sleep. I can make any temporary restoration for natural teeth or implants on the spot. On one occasion I even created an entire temporary denture for a patient from scratch while she sat in the chair!
Skills like carving temporary restorations are not part of dental school curricula. So what are dental students learning in the dental schools today? They are learning advanced digital techniques with state-of-the-art equipment. Ironically, they most likely won’t have access to this equipment in their residency programs. What are they going to do there without analog skills?
I think the best approach for dental education is to learn “analog” first and then learn “digital.” As I mentioned earlier, neither approach is the be-all and end-all and I can combine both for the most ideal result. I believe that if the digital student understands analog–how to physically carve and manipulate teeth–the transition to digital will be much easier. After learning analog, basic concepts are already visualized and imprinted in the brain.
Before I moved to Arizona, I applied to teach at a brand-new dental school that was built just five miles from my house. Never in my life would I have believed that building such a school in my neighborhood would become reality! I served on my component society’s liaison committee to the new school and I applied for a part-time faculty position. I told the interviewers (who already knew me personally) that I could teach the dental students techniques that were beyond what most attending dentists in residency programs could do. The new school had no track record with residency programs, since it hadn’t graduated a single class. Having uniquely trained students would have put that school “on the map” immediately and the new school would hit the ground running with a fabulous reputation.
But even though I was well known and highly regarded in the vicinity, the new deans didn’t want me. It was immediately clear to me that this dental school was going to be no different than any other. In dental education everyone must march in lock step; and outsiders need not apply. Anyone who thinks differently is to be shunned. The deans were set on perpetuating dental school hierarchy by enticing professors from nearby dental schools to serve on their faculty.
Never in my life did I expect to be considered as a radical outlier. I was classically trained by a master and pioneer of full coverage restorative dentistry, and the techniques I use actually hail from the roots of full coverage dentistry. These techniques have the track record for the best OUTCOMES. This is the REAL evidence-based dentistry! I can show many cases which have been in the mouth for decades and documented WITH follow-up X-Rays for comparison. This is the OUTCOME that counts–regardless of whether analog or digital techniques are utilized.
These days I do not see any educators showing case OUTCOMES with follow-up X-Rays at continuing education courses. All that is shown is the esthetic result on the day of insertion. I believe strongly that the desired OUTCOME should be measured in terms of health and case longevity. Cases fabricated with analog techniques, digital techniques or a combination of both should all be judged in the same way. Esthetic improvement may be dramatic, but esthetics alone does not demonstrate successful OUTCOME. X-Ray follow-up of at least five years is required to ensure a reasonably good OUTCOME. My father and I always considered full coverage restorations that did not last at least TEN years to be failures. As dental health professionals we should care most that our efforts corrected dental problems and eliminated disease. While esthetics certainly is important, we are doctors first. We are not cosmeticians.
1Brown, Bill; Digital vs Analog in Art; https://www.ehow.com/about_6323970_digital-vs_-analog-art.html
2The importance of case OUTCOME cannot be over-emphasized. For this reason, every instance of the word “OUTCOME” in this blog is spelled with capital letters.
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