Written by David Clark, DDS Sunday, 31 October 2004 19:00
One of America’s best-known architects, Frank Lloyd Wright, once said, “The physician can bury his mistakes, but the architect can only advise his clients to plant vines.” Recent dramatic changes in the practice of dentistry have placed us in a position that is now very similar to Wright’s architect. Patients now “grade” their dentists on the aesthetic quality of their results, and the bar goes ever higher.
Like me, the majority of dentists practicing today were trained in dental school to restore teeth using amalgam and gold. Composite was only for anterior teeth, and porcelain was supported by a metal coping. Trying to “graft” aesthetic dentistry and bonded porcelain to this old tree of knowledge is often pointless. It is time to burn that tree down and plant a new one because everything just changed. In this final article in a series of articles highlighting the impact of the operating microscope in dentistry, I will touch on tiny segments of the myriad of aesthetic issues the clinicians of the Academy of Microscope Enhanced Dentistry have raised.
AESTHETIC DENTISTRY IS MUCH MORE THAN PRETTY PORCELAIN
Micromisfits cause tissue response that can doom a case. In addition, the microleakage that in years past simmered uneventfully for years or decades can now cause immediate and cataclysmic aesthetic failure (Figure 1).
|Figure 1. This all-porcelain crown began to microleak and turn gray after just a few weeks. The dentist had enjoyed success with porcelain-fused-to-metal crowns for 20 years of practice prior to this failure. These failures may become epidemic as PFM crowns are phased out.|
A patient recently joined our practice with a story and wake-up call that illustrates this point. Her previous dentist had placed a crown on tooth No. 19 that subsequently required endodontic therapy. I asked her if that was the reason she had sought out a new dentist. She replied, “No, I haven’t finished my story.” The reason she left her previous dentist was that the composite repair in the endodontic access was gray and kept getting grayer. When she complained about this to the dentist, he responded that it was the best he could do. His best was not good enough. Microleak-age, together with a lack of opacifiers, had lost the day. The use of microscopic visualization will shed light on answers to these problems.
The qualities that give porcelain and composite their beauty also rob them of their visual contrast against teeth and stone dies.
In addition, their translucent nature further masks their fit. Amalgam and gold are reasonable materials when used with low or no magnification. Tooth-colored materials, in contrast, require 5 to 10 to 20 times as much magnification. Magni-fication has simply not kept up with the dramatic changes in both materials and patient expectations. In spite of other advances in dentistry, marginal integrity, emergence profile, and resistance to microleakage have all taken a giant step backward.
THE ART OF THE POSSIBLE: CASE 1
The microscope made quite a dramatic difference in the care of another of my patients. His distraught parents brought this 8-year-old boy to the office just as I was about to head out the door one afternoon. His central incisors had been smashed (Figure 2) in a fall at a roller rink. In years past, I would have initiated endodontic therapy and begun post/composite buildups. But in today’s practice, with the operating microscope at hand, I am able to do “much less” and accomplish “much more.” Exquisite microscope-guided treatment of this case represented the pinnacle of health and aesthetics (Figure 3), but it did not involve porcelain or exotic composite layering.
|Figure 2. Case 1: Devastating fractures at a young age can lead to a lifetime of embarrassment and re-treatments||Figure 3. Case 1: Immediate postoperative result. Microscopic visualization allowed intimate union of the fragments to teeth.|
I began by asking the parents if they kept the boy’s tooth fragments. Fortunately, they had picked them up (Figure 4) for his scrapbook. I administered anesthesia and placed a rubber dam. The pulp exposure was not bleeding when he arrived. Using the operating microscope, I next performed an absolute deplaquing of both teeth and fragments at 16x. I then examined the fragments from a variety of angles at 10x to verify fit and familiarize myself with their shapes. At this point I phoned Dr. John Khademi, a founding member of the Academy of Microscope Enhanced Dentistry, for advice. He was brief: “Leave the pulp!”
Next, I administered a brief application of sodium hypochlorite to tooth fragments, teeth, and exposed pulp. Then I gently shaved back the pulp at 24x (Figure 5)—without causing any bleeding—in order to compensate for any swelling of the pulp that could impede full seating of the fragments and to create a little more space to seal the chamber. (My motto: “The seal is everything.”) The next step was selective etching (Figure 6) of the enamel (20 seconds), the dentin (10 seconds), and the pulp (5 seconds). I then verified the absolute absence of weeping or hemorrhaging of pulp by observing for 30 seconds at 24x.
|Figure 4. Case 1: These tiny tooth fragments seem like so many fingernail clippings at no magnification. At high magnification, their beauty and true worth can be appreciated.||Figure 5. Case 1: Flame-shaped coarse diamond bur is utilized to shave back tiny, mushroom-shaped pulpal tissues. No bleeding resulted.|
With the room lights off and an orange microscope filter on, I then began bonding just as I would a porcelain laminate. The orange filter afforded extended working time, which was a huge advantage over other ap-proaches, particularly in this instance when it took several minutes to line up tooth fragments perfectly. I stayed at 24x, teasing and pumping the fragments into maximal interdigitation. The use of flowable composite (Filtek Flow, 3M ESPE with Opti-bond Solo Plus, Kerr) permitted me to achieve a microscopically satisfying fit, while the microscope and orange filter relieved me of the misery of manipulating tiny fragments I could hardly see as I worried about premature polymerization from an operatory light. (I used flowable composite because most composites and composite cements are too viscous to allow consistently complete seating when viewed at high magnification). Final polish was simply a few light strokes with a brownie point at 16x. Over polishing is a concern.
|Figure 6. Case 1: Selective etching at 24x. Note how microscopic visualization allows ideal etchant control. We cannot afford pulpal hemorrhaging as a result of excessive contact with etchant.|
The outcome of this treatment was outstanding aesthetically and biologically, for nothing could be more natural than recycling the patient’s own enamel. The best long-term aesthetic treatment in this case was to maintain the pulp for as long as possible. Pulpless teeth have been described as “a car without a driver.” The proprioception of the pulp provides protection. An additional goal is to delay and minimize the inevitable darkening of a nonvital tooth. Frequent and regular follow-up visits with the patient have shown the root continuing to mature with vital pulp. It has been wonderful for me to have achieved such an excellent treatment result for this young man, a result that would not have been possible without the operating microscope.
MICROSCOPE-ASSISTED PRECISION IN PORCELAIN ADAPTATION: CASE 2
The patient presented with severe enamel mottling. She had been waiting most of her adult life for the right time to treat the aesthetic problems (Figure 7). In this case, I chose bonded porcelain re-storations (Empress 1, Ivoclar Vivadent). I placed most of the finish lines either slightly subgingival or equi-gingival because while there was no enamel on most of the facial surfaces, enamel was present at the CEJ. I therefore had the luxury of bonding to enamel at the margins, which I find to be more predictable and potentially more permanent. “Burying” the margins, on the other hand, would have meant moving them past the enamel onto dentin. I have confidence bonding to enamel. I tolerate bonding to dentin.
Postoperative photographs (Figure 8) show optimum tissue health that was rarely this aesthetic before I incorporated microscopic visualization for preparation, im-pressing, temporization, presculpting of finish lines, and seating. Gingiva loves microscopically adapted and in-credibly smooth porcelain. At 24x, absolute cement removal is possible. Many clinicians using the operating microscope report that microscopically adapted and polished porcelain can resist plaque buildup more effectively and promote better tissue health than natural enamel or cementum.
|Figure 7. Case 2: Preoperative photograph. Interesting enamel hypoplasia left her maxillary anteriors deficient of most of the facial enamel||Figure 8. Case 2 Continued: postoperative photographs. Predictability in marginal and gingival aesthetics is a priceless benefit of the microscope. Ceramics by Peggy J. Parker at DTI.|
TECHNICIANS CAN BE THE MISSING LINK
Microscope dentists enjoying newfound precision with preparations and impressions may well become frustrated with ceramists whose work becomes the weak link in precision. In my case, I wandered from lab to lab toiling with ceramists who, though they had lab microscopes, were unwilling to treat my cases with special care (Figure 9).
|Figure 9. A brownie point at 24x was used to trim finish lines with less than 0.75 mm of emergence profile in the impression. Other modalities can cause chunks of the marginal stone to tear away with the excess.|
One of the most challenging steps in the quest for precision in porcelain is the visual challenge of lack of contrast. In addition to the stark color contrast it offers, gold casts a useful shadow when viewed directly on the tooth or die. Unfortunately, most technicians use the visual approach that works well with gold when analyzing porcelain. While gold may be analyzed by looking directly at the margin-die interface, I have found that porcelain must
be evaluated in profile. Together with my ceramists, I have created a protocol to produce porcelain and porcelain-fused-to-metal restorations that hold up consistently to the scrutiny of 16x. One component of the system is the 3-die protocol that gives me a virgin die for performing an evaluation and final sculpting of the finish lines. In order to implement this entirely new level of precision, Chuck Rickabaugh at Twin Lakes/DTI actually created a lab within a lab. It can be done!
INTERNAL SURFACES OF PORCELAIN RESTORATIONS AT 16X: PREPARE TO BE HORRIFIED
The internal aspect of porcelain (porcelain butt margins, porcelain crowns, porcelain laminates) may be smooth, glazed, or contaminated on part or all of the porcelain. Powdery salts may be left behind from hydrofluoric acid-etching. Chunks of die stone and pencil marks may be everywhere. Ramifications of internal surfaces are significant. These contaminations are ignored by many technicians and unseen by dentists, especially when it comes to full crowns. One former ceramist commented, “If you aren’t bonding the crown, why does it matter?” It matters.
GINGIVAL PORCELAIN FINISHING BURS ARE UNNECESSARY IN A MICROSCOPE-CENTERED APPROACH
Mainstream dentistry is moving toward the creation of 2 margins: porcelain and a composite margin. Porcelain that is several hundred microns off in both horizontal and vertical axes are theoretically sealed by the new, superviscous composite ce-ments. Margins that are accessible are sometimes dressed down with finishing burs. These protocols are the standard of care, but when their results are viewed under the microscope, we see the following:
•The high luster of porcelain cannot be fully re-established near the sulcus with the “dressing down” of porcelain margins.
•The cement margin portion is chalky and becomes even bumpier over time.
•The composite margins are prone to microleakage.
•The fear of marginal aesthetics has driven clinicians to “bury” these margins, creating a whole new set of problems.
•Over time the gingival tissues have subtle or not-so-subtle inflammation that manifests as the purple color that many patients deem unattractive.
•The new, superviscous cements are creating ever widening marginal gaps, as the crown or veneer cannot be wrestled fully to place.
At our microscope-centered, hands-on porcelain laminate courses at the Newport Coast Oral Facial Institute and Precision Esthetics Northwest, there are no gingival finishing burs. The concept is different. With microscope precision, the excess luting cement is “scissored” away cleanly as the ultraprecise laminate is seated. There is only one margin—a laboratory or chairside presculpted, prepolished porcelain margin.
3 MYTHS OF THE MICROSCOPE
Myth No. 1: Microscopes aren’t practical in a “normal” restorative practice. In fact, restorative dentists are elevating their vision to “microscope-centered practices” all over the world. In our courses, we are seeing clinicians become comfortable using a microscope in a single day. During one of our hands-on courses, a microscope sales representative made this observation: “I guess they (clinician students) didn’t know it is supposed to be hard.”
Myth No. 2: Microscopes are rigid and cumbersome. Though it is true that many endodontists have rigid microscopes laden with heavy peripherals (a perfectly satisfactory arrangement in endodontics), I have found in my restorative practice that I can set up my microscopes to move constantly and easily. With a little patience and practice, microscopes can become nearly as flexible as loupes, so long as the microscope is not “loaded up.” In Figure 10, I am working in the 9 o’clock position with only a tiny lipstick video camera.
|Figure 10. Dr. Gary Carr, pioneer of microendodontics, is pictured at right with several pounds of peripherals on his microscope. For Dr. Carr, the microscope is fairly stationary, and the patient moves to the microscope. The author is pictured at left. For the daily routine of full-time microscope use in restorative, he has unloaded his microscopes, which allows easy, light movement that genuinely feels much the same as loupes.|
Myth No. 3: Microscopes are expensive. Unlike most cutting-edge, high-tech dental gadgets, microscopes have reached a high state of evolution and may never wear out or become obsolete like a computer or a curing unit. Some microscopes have lifetime guarantees. Despite a significant initial cost, therefore, the amortized cost is quite low. In addition, a microscope can allow you to forgo instruments and materials that are unnecessary in the microscope-centered setting, further saving money and time.
There are gifted clinicians who operate with little or no magnification and do breathtaking aesthetic dentistry. The microscope does not make one dentist better
than another. Nonetheless, a few accomplished restorative dentists, though their dentistry was already exquisite, have embraced the use of the microscope. Examples of such clinicians are Dr. Cherilyn Sheets and Dr. Mark Fried-man, who report that it has brought greater predictability and joy to their dentistry. Excellence in dentistry is a choice, and magnification can be a powerful asset in achieving it.
The testimony of doctors who use the microscope daily in their practices confirms its value. An overwhelming majority affirm that it has improved their clinical skills. The microscope, with instantaneous magnification from 2.5x to 24x, no visual noise, and shadowless coaxial light, offers the best means for achieving complete visual information in dentistry. It can nurture great confidence, healthier posture, and better and surer hands for the clinician. And in the end, the excellent visual information it offers can help the doctor to create more precise, more healthful, and more aesthetically pleasing dentistry.
Disclosure: Dr. Clark is not a paid spokesman for any microscope manufacturer. Royalties from sales of the Clark Explorer Series are donated to the Academy of Microscope Enhanced Dentistry.
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