Ask Dr. Christensen

In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers.

by Gordon J. Christense, DDS, MSD, PhD

In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers. If you would like to submit a question to Dr. Christensen, please send an e-mail to info@pccdental.com.

Q The nonprep, thin veneer concept appears to be more popular than ever. Patients are requesting this type of veneer, and dentists are placing more of them instead of conventional ceramic veneers. I have observed many companies promoting these conservative restorations. I have been doing conventional ceramic veneers for many years with great success. Are there reasons to change to the nonprep bonded ceramic veneer?

A The conservative veneer concept is not new. More than 20 years ago, the nonprep veneer was suggested and promoted by Den-Mat. The company now has a signifi cant advertising campaign directed not only to dentists but also to the general public. As a result, although there are numerous brands available, patients are actually asking for conservative veneers by the brand name LUMINEERS"!.

What are the advantages of the nonprep veneer concept? Obviously, the patient does not worry about pain or tooth structure being removed since only the most out-ofline teeth need to be contoured slightly. Anesthetic is not needed, which is attractive to many patients. The procedure to slightly contour the teeth to be veneered and seat the nonprep veneers is relatively painless and comfortable. After many years of service, the veneers can be removed and replaced with minimum effort and little or no discomfort to patients.

There also are some disadvantages. The teeth being veneered must receive more contour than the original shape, ranging from 0.3 mm and up. When overdone or on already protrusive teeth, this much additional bulk can be objectionable to patients and false looking to observers. Placing a single tooth nonprep veneer is very diffi cult because the color and contour of the veneered tooth is almost always different from the adjacent natural teeth.

Therefore, patients who receive nonprep veneers almost always require them on several teeth to provide homogeneous contour and color. Because the laboratory work is similar in time and skill to making a typical crown, the lab cost is similar to that of conventional veneers and crowns. This makes the clinical fee equal to or higher than conventional ceramic veneers or crowns.

The indications for nonprep veneers are quite logical. If the teeth are inclined lingually, nonprep veneers can build them facially to provide near normal contour and anatomy. If the teeth to be veneered have diastemas -- and add-on resins are contraindicated for some reason -- nonprep veneers can fill the diastemas easily and provide only a small additional facial bulk to the teeth. If the teeth are pointed or developmentally defi cient, nonprep veneers are an excellent solution.

The contraindications are also obvious. If the teeth to be veneered are normal in contour or large and facially located, adding more contour to the facial surfaces gives the appearance of "buck teeth," with an overcontoured and false look.

Your question is a good one. Yes, for certain situations, nonprep veneers are an excellent, noninvasive, and beautiful choice. But they are not for everybody.

I have demonstrated my views on the clinical procedure for nonprep veneers in our newest video -- V1521 "Lumineers -- Well Proven, Conservative Veneers." For more information, call Practical Clinical Courses at (800) 223-6569 or visit our Web site at www.pccdental.com.

Q I have heard that some of the laboratory work requested from dental laboratories within the United States is really coming from developing countries. This concept disturbs me. How can I tell if my laboratory work is not being done in the laboratory to which I have sent the case?

A At this time, estimates of laboratory work being done offshore and delivered in the U.S. range from 10 to 20 percent of the total lab volume, and it is increasing rapidly. American laboratories are being solicited by offshore laboratories in numerous countries. The fees that the offshore labs charge the American labs are considerably lower than the cost for American labs to construct your laboratory requests. The result is higher profit for the American labs when they use offshore services.

From personal observation of the offshore products, I can state that some of the work is very good and would compete with American quality, while other offshore labs are not up to our standards. Some laboratory owners are informing clients about the location in which the laboratory work is fabricated.

Some labs have different fees for work fabricated in their own labs vs. work that is fabricated offshore, and they are telling clients why the fees are different. As is the case in all vocations, some labs are less honest. These labs are not informing clients about the use of offshore products.

I agree that I would prefer to know where the laboratory work is being accomplished. I also would prefer to know the categories and name brands of the materials used in the fabrication of the prostheses and the infection-control standards of the offshore laboratory.

The federal government should analyze these offshore products as they come into our country, but their overloaded employees are not able to cope with the enormous quantity of laboratory work coming into the United States. The responsibility to check these labs rests with you and me!

The offshore laboratory challenge will continue to grow, and eventually this segment of lab work will become a major part of the American laboratory industry. The resultant decrease in American lab technicians and American influence in the laboratory industry has significant, but unknown, consequences. It appears that, as developing countries progress and become more affluent, those countries in which the offshore lab work is now being done for U.S. dentists will need their own dental laboratory support for their domestic dentists. The challenge to the American lab industry may be self-limiting. Only time will prove or disprove this statement.

To answer your question, I suggest that all dentists have a face-to-face interview with the owner of the dental laboratory they are using, and ask a direct question of the owner about the location in which the work is being fabricated. Assuming the lab owner is honest, he or she will answer your question. If that answer does not satisfy you, change to a lab where you can get an answer to the question.

Q When seating an all-ceramic or porcelainfused-to-metal prosthesis, I often have to adjust the ceramic on the occlusal surfaces. What is the best way to smooth the ceramic?

A Although all of us have to adjust and polish ceramic surfaces occasionally, the best way to have a smooth surface on the ceramic over a long period of service is to leave the glaze in place and not remove any ceramic at all. According to scanning electron microscope observation in our research laboratories (CRA), the ceramic surfaces can be smoothed to appear very shiny to the naked eye or loupes. But the ceramic surface roughens again after a few months of chewing. The result is abrasion of opposing tooth structure or restorative material. I suggest warning the patient at the seating appointment that the teeth on the opposing arch may need to be smoothed, assuming that they are natural teeth. Minor adjustments can be made in opposing enamel without a problem. The result is a prosthesis with the smooth, long-lasting glaze still intact.

In spite of all of us not wanting to send the prosthesis back to the laboratory, if large portions of ceramic have been removed at the seating appointment, the case should be reglazed for optimum longevity and smoothness.

When many teeth are being restored with ceramic or PFM crowns, it is nearly impossible to seat them without adjusting the occlusion, thus removing some ceramic on the occlusal surfaces.

If removal of ceramic is necessary before or after cementation of ceramic restorations, which is often the case with multi-unit restorations, I suggest the following technique:

  1. Smooth the affected ceramic surfaces with a mediumtype composite disc.
  2. Further smooth the ceramic with a pre-Dialite® polishing wheel (Brasseler).
  3. Develop a shine with a Dialite wheel (Brasseler).
  4. Develop a higher shine with a polishing paste on a stiff brush. A great polishing paste example is VH Technologies polish (www.vhtechnologies.com). Some of the instruments described are available to fit either straight-handpiece mandrels or contra-angle mandrels. The preceding finishing and polishing procedure develops ceramic surfaces that are extremely smooth when finished. The smooth surface retains itself relatively well over a period of service.

Dr. Christensen is a practicing prosthodontist in Provo, Utah. He is the founder and director of Practical Clinical Courses, an international continuing-education organization initiated in 1981 for dental professionals. Dr. Christensen is a cofounder (with his wife, Rella) and senior consultant of Clinical Research Associates which, since 1976, has conducted research in all areas of dentistry and publishes its findings to the dental profession in the well-known "CRA Newsletter." He is an adjunct professor at Brigham Young University and the University of Utah. Dr. Christensen has educational videos and hands-on courses on the above topics available through Practical Clinical Courses. Call (800) 223-6569 or (801)226-6569.

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