Ask Dr. Christensen

May 1, 2002
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 email to [email protected].

by Gordon J. Christensen, 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 email to [email protected].


A frequent frustration for me is temporizing a porcelain veneer case. Invariably some of the temporary facings fall off, even when I confirm that the occlusion is "clear." Is there a predictable technique to keep temporary facings in place for the usual two-week provisional period?

Answer from Dr. Christensen…

You have described a very common problem. I have placed ceramic veneers for more than 15 years, and the most frequently occurring challenge is retention of resin temporary restorations. I have some preventive measures that will help you alleviate this problem:

  • Schedule ahead with your laboratory so that the provisional restorations have the shortest service period required as possible. We try to arrange for this lab time to be only a few days.
  • Caution your patients to be very careful with the temporary restorations while they are in the mouth.
  • Ask patients to chew on the posterior teeth as much as possible while the provisional restorations are in place.
  • Provide patients with some easy-to-use temporary cement that they can carry in a pocket or purse for an emergency situation. This can be a tube of jelly-like denture adhesive that will hold the temporary in place until it can be reseated.
  • Educate dental assistants to make and replace provisional restorations to minimize chair time when a temporary does come off.

Now that you have given some preventive suggestions to patients, incorporate a few positive changes into your technique. Make the provisional restorations from the resin of your choice. One of the most aesthetically acceptable resin types is bis-acryl, such as ProTemp 3 (3M ESPE) or many others. Bis-acryl has a translucent appearance that takes on the color of the underlying tooth structure and the cement you use.

To make the provisional restoration, I prefer to use a vacuum-formed matrix that is made from a stone cast of the original tooth anatomy or a cast of a more ideally waxed-up anatomical form. Place the resin into the matrix and seat it on the tooth preparations. Once the resin sets, it can be taken off in one piece. Often, there is very little finishing to do. Use a standard, controllable acid-etch gel, such as Ultraetch from Ultradent, to etch a 3-mm circular portion of enamel in the exact center of the facial surface of the tooth preparation. Seat the temporary restorations with the same resin cement that you plan to use for the final cementation, or you may use a resin-based temporary cement, such as Tempbond Clear (Kerr).

Taking the precautions explained above, I have experienced only minimal problems with provisional restorations for veneers.

One of our recent, 60-minute videos shows the veneer procedure in detail: V1584, "Veneers - All Types." Call Practical Clinical Courses at (800) 223-6569 or visit


After several years of pondering the use of air abrasion, I am still undecided whether to buy an air abrasion unit or stay with conventional or newly designed rotary burs for minimal carious lesions. What do you advise?

Answer from Dr. Christensen…

Most dentists still use conventional or very small burs for minimal tooth preparations, but a loyal and devoted group of dentists is completely convinced that air abrasion is better.

The known advantages of air abrasion are clear:

  • The procedure can be nearly painless in many situations.
  • Tooth cuts are nontraumatic and do not make cracks in teeth.
  • The cuts are minimal in size.
  • There is no air-rotor noise or odor produced by cutting tooth structure.

On the other hand …

  • The devices range in cost from approximately $1,000 to $17,000.
  • The aluminum oxide debris in the office is significant.
  • It is difficult to predict which patients will not require anesthetic.

My candid suggestion is that if you accomplish a significant amount of operative dentistry, especially on children and adolescents or elderly people, get an air abrasion unit. A device that has received good evaluations in Clinical Research Associates tests is the Prep Start from Danville Engineering.

If most of your dentistry is more complex and you do not perform many minimal operative dentistry procedures, I suggest using conventional cutting devices or small, specially designed burs such as the Fissurotomy Burs from S.S. White or other similar burs.

One of the upcoming presentations for our new Forum Video Series will discuss the controversies associated with this topic: F1202, "Air Abrasion." The video will be available in December 2002.

Dr. Christensen is a practicing prosthodontist in Provo, Utah. He is the founder and director of Practical Clinical Courses, an international continuing-education organization for dental professionals initiated in 1981. Dr. Christensen is a co-founder (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.

Dr. Christensen's views do not necessarily reflect the opinions of the editorial staff at Dental Economics.

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