Ask Dr. Christensen

Feb. 1, 2003
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

Question ...

Recently, I heard during a continuing-education course that "self-etching" primers do not create an adequate bond to enamel when compared to "total-etch" bonding agents. I prefer to use "self-etch" solutions because there is less post-operative tooth sensitivity, but I do not want to have reduced enamel retention. What type of bonding agent is best?

Answer from Dr. Christensen ...

Etching enamel with phosphoric acid creates a significant bond. Clinicians know that post-operative tooth sensitivity is common with some Class I, II, and V tooth restorations when "total-etch" bonding systems are used. The perpetual question for clinicians is: Should they change to "self-etch" systems to avoid the potential of sensitivity, or should they continue to use "total-etch" systems?

There are many brands of "self-etch" products on the market, but reliable comparisons of all of the many brands are not available. Most of the popular brands of "self-etch" primers are producing adequate bond strength to enamel. One popular brand is SE Bond by Kuraray.

A few brands of "self-etch" primers are less effective than phosphoric acid, but some have shown retention to treated enamel equal to that of "total-etch" systems. The seal of dentin surfaces attained with "self-etching" primers has been shown to be similar to that of properly used "total-etch" systems. Experienced clinicians accept lack of post-operative tooth sensitivity produced by "self-etching" primers.

Most typical tooth preparations, Class I through V, have retentive features placed in them by the practitioner. They do not require additional enamel retention provided by the acid-etched surfaces. However, there are some types of restorations that require additional retention of resin restorative material or resin cement afforded by acid-etch irregularities. Examples are ceramic or polymer veneers placed over acid-etched dentin surfaces, or tooth-colored inlays or onlays placed in clinical situations where there is minimal mechanical retention.

If you have any doubt about the ability of your "self-etch" primer to produce adequate bond to enamel, or for some reason you want to ensure optimum bond to etched enamel, I suggest the following technique: Carefully etch the enamel surfaces with controlled phosphoric acid gel, such as Ultradent's UltraEtch, before placing the "self-etching" primer on the entire preparation. Be careful to avoid getting phosphoric acid on the dentin surfaces, since the opening of the dentinal canals caused by the acid etch, and the potential lack of a seal effected by the subsequent primer, may still create post-operative tooth sensitivity.

A Practical Clinical Courses video demonstrates successful use of "self-etching" primers in clinical practice. Item number C501B, "Predictable, Long-Lasting Class 2 Resin Restorations" can be purchased by contacting us by phone at (800) 223-6569, by fax at (801) 226-8637, or visiting our Web site at

Question ...

When a restoration fails, when should the patient be given a refund or free redo for the procedure?

Answer from Dr. Christensen ...

You have asked a very important public relations question. The answer will differ from practice to practice. I will express my own opinions on the question based on many years of experience.

The first premise is that the patient's opinion should almost always be respected as correct. Most patients will accept a reasonable solution to this problem. Deciding when to discount a redo fee when a restoration has failed is a delicate and personalized matter.

My own decisions vary from situation to situation. If the restoration has been in service for a short time (up to two or three years), I feel that the patient deserves a new restoration at no charge. You know how you would feel if your new automobile ceased to function after only several months of service. Often, it is faster to redo a simple restoration than it is to hassle with the patient about redoing the restoration for a fee. Furthermore, the ill will caused by a debate over payment for the failed restoration is never good.

If the restoration has been in service for three to five years, or if the patient was partially responsible for its breakage, I feel that a partial refund of the cost of the redo is in order. My usual reduction is 10 to 50 percent of the restoration cost, depending on the apparent cause of the failure.

If the restoration has been in service for five to 10 years, patients usually accept that it has had a reasonable service life. On such failed restorations, I may deduct a small percentage of the fee as a gesture of goodwill.

After a restoration has served for 10 or more years, it is unlikely that the patient will object to paying the full fee, and that approach seems fair to me. I have always tried to be fair and honest with patients. I attempt to put myself in the patient's place, and make an effort to ensure that the patient leaves the office with a positive feeling about the experience. Patients will discuss a positive experience with many other potential patients, and they also will discuss a negative one in equal detail. A negative experience has the same profound negative impact on our practices.

Two Practical Clinical Courses videos related to this topic have been very popular and useful. Item numbers V19-93, "Long-Term Maintenance and Repair of Fixed Prostheses" and V4744, "Malpractice Suits, Prevention or Coping with One" can be purchased by contacting us by phone at: (800) 223-6569, (801) 226-8637 fax, or visit our Web site at

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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