Ask Dr. Christensen

Jan. 1, 2002

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].

Question ...
I have a patient who requested two amalgam fillings to be replaced with resin-based composite. The fillings were small- to medium-sized Class I's. Since they were done, the teeth have been sensitive when biting on the fillings. I replaced them with other composites. I made sure that the resin was placed in layers and light-cured with the Virtuoso Arc light, but the sensitivity continues. What can I do? I feel bad, because the teeth were fine before this treatment.

Answer from Dr. Christensen ...
I have heard this question many times before. In spite of the significant advertising that claims certain bonding agents will stop sensitivity in Class I and Class II restorations, many of the products do not stop this postoperative tooth sensitivity. In my opinion, from experiences on the lecture circuit, as many as 25 percent of Class I and II resin-based composite restorations have postoperative tooth sensitivity that lingers from a few weeks to prolonged sensitivity requiring endodontic therapy.

Many papers in the literature emphasize the bond of resin to dentin, yet fail to state the level of tooth desensitization afforded by the product. How important is the bond to dentin if the tooth requires root canal therapy after the restoration is placed?

Many years ago, after accomplishing hundreds of these types of restorations myself and suffering through several years of tooth sensitivity, I have finally solved the problem in my own practice. There are several ways to prevent postoperative tooth sensitivity on a predictable basis. You do not have to use all of the following techniques at one time. I will state my own technique at the end of my response to this question.

  • Use a resin-reinforced glass ionomer (RRGI) liner on the virgin-cut dentin surface. Vitrebond (3M/ESPE) or Fuji Lining Cement LC (GC America) placed about one-half millimeter thick over most of the dentin will stop almost all sensitivity.
  • Use a self-etching primer. Self-etch products — such as Clearfil SE Bond (Kuraray), or Prompt L-Pop (3M/ESPE), or Touch & Bond (Parkell) — used after the resin-reinforced glass ionomer liner almost assuredly prevent postoperative tooth sensitivity. (Unless you use it perfectly, avoid the so-called "total etch" concept.)
  • Use a flowable resin after the placement of the bonding agent. This layer of thinned restorative resin reduces the sensitivity.
  • Do not overdry the tooth preparation at any time. About one second of air blast is enough for most drying needs.
  • Use a desensitizer, such as GLUMA (Heraeus Kulzer) or Microprime (Danville Engineering).
  • Make sure the curing light you are using is adequate by testing it with a radiometer. A good radiometer is the Spring 3K Light Meter by Spring Health Products — (800) 800-1680.

I prefer to use Items #1 and #2 above in that order. Place the RRGI first, follow with a self-etching primer, and bond. Cure; then place the restorative resin incrementally and cure.Postoperative tooth sensitivity is history with this technique.

A recently made Practical Clinical Courses video shows my Class II resin-based composite technique in detail — Item #C501B "Predictable Long-Lasting Class II Resin Restorations." Call (800) 223-6569 or visit

Question ...
I have been told that I shouldn't use a local anesthetic containing a vasoconstrictor when I am treating patients who have had heart problems. Occasionally I need the vasoconstriction in certain clinical situations. What can I use to control bleeding and prolong the anesthetic effect in those situations?

Answer from Dr. Christensen ...
Most authorities agree that cautious use of local anesthetics containing vasoconstrictors is acceptable for patients who have had heart problems. The recommended maximum dosage for these patients is one 1.7-1.8 ml cartridge of anesthetic containing 1:50,000 epinephrine, or two cartridges of local anesthetic containing 1:100,000 epinephrine. When treating patients who have had heart problems and who need to have several oral treatment procedures accomplished, I use local anesthetics without a vasoconstrictor for the simple, fast procedures and save the vasoconstrictor-containing anesthetics for the more difficult, potentially painful, or longer procedures.

A Practical Clinical Courses video is available on a subject related to the above question — Item #3973 "Easy Management of Medical Emergencies." Call (800) 223-6569 or visit

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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