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Ask Dr. Christensen

Oct. 1, 2006
In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics® readers.

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 [email protected].

Q I have noticed a significant emphasis in journals and lectures encouraging dentists to use all-ceramic crowns and resin-based composite restorations instead of porcelain-fused-to-metal (PFM), gold alloy, and amalgam restorations. Should I yield to this trend, even though I prefer to use conventional long-proven materials and techniques?

A Amalgam, gold alloy, and PFM restorations are still considered to be state-of-the-art. In the United States, they are the most used for intracoronal restorations and crowns, respectively. Many dentists would rather use conventional materials and techniques than the newer concepts. There is nothing wrong with that opinion.

At top, before upper rehabilitation; at bottom, after maxillary Lava®rehabilitation.
Click here to enlarge image

Patients should be advised during their informed-consent education session about the availability of the alternative forms of restorations. Assuming they have confidence in you and your clinical ability, they will listen to your opinions and observations on the desirability of the various restorations for their own treatment. In the event that they would prefer to have resin-based composite restorations or all-ceramic crowns, you should be prepared to provide those restorations, which are also considered to be state-of-the-art. In my opinion, dentists should offer their patients the currently accepted options for therapy.

At top, before mandibular anterior rehabilitation; at bottom, after mandibular anterior rehabilitation with Cercon®.
Click here to enlarge image

The current generation of resin-based composites can compete well with amalgam in small- to moderate-sized restorations when placed correctly, and they are certainly better than amalgam from an esthetic standpoint. Furthermore, the zirconia-based crowns and fixed prostheses are gaining in popularity, and both laboratory and clinical research on them appears to be very positive. Products such as 3M ESPE’s Lava and Cercon® from DENTSPLY have now had enough research to be considered successful restorations as observed over at least a few years.

In summary, I suggest offering patients complete informed consent, including the alternatives for treatment for their situation, the advantages and disadvantages of each, the costs of each treatment, the risks involved, and what happens if nothing is done. When that information has been provided in detail and the patient has had the opportunity to discuss the options with you, I suggest that you and your staff should be capable of providing all of the state-of-the-art restorations, including resin-based composite and all-ceramic restorations.

Our new PCC video, V3519, “Predictable, Non-Sensitive Resin-Based Composite Restorations,” shows in close-up live action the placement of typical Class II, III, IV, and repair restorations. For more information, contact Practical Clinical Courses at (800) 223-6569, or visit our Web site at

Q I have read several articles that promote the use of flowable resin-based composite restorations in many clinical situations, including restoration of Class I and Class II locations. To date, I have not found this many uses for flowable resin-based composites. I am concerned about the use of flowable restorative resins in areas of occlusal wear. What am I missing?

A Flowable resins have a few good uses, but in my opinion, they are being significantly overused. You will remember that a flowable resin is a thinned-down version of a fully-filled restorative resin. In most brands of flowable resin, the physical characteristics have been depreciated when compared to full-filled restorative resins from the same companies, including reduction of strength, higher wear expectations, higher polymerization shrinkage, greater expansion and contraction during service, and overall reduced potential for long-term service when exposed to oral conditions.

The most significant positive characteristic that flowables have is “flow.” If that characteristic is necessary in a specific situation, then a flowable resin should be used. They should not be used in wear-prone situations. Flowable resins appear to be acceptable for use on the inside of typical fully-filled, resin-based composite restorations to provide easy adaptation into intricate irregularities or retentive features, and to potentially provide some flexibility in the restoration to reduce stress.

However, other techniques also can be used to encourage “flow.” If a typical fully-filled restorative resin is allowed to remain on a tooth preparation for a few seconds, it absorbs body heat, and the material soon becomes more flowable. In fact, it may have as much flow as some of the so-called flowables. Almost without exception, such fully-filled restorative resins have better physical characteristics than the commercially-produced, thinned-down flowable resins.

Although use of flowable resins is popular because of their ease of use, I do not find many significant uses for flowable resins that cannot be achieved as well or better by fully-filled, properly-used conventional restorative resins. In my opinion, flowable resins are a valuable adjunct to fully-filled resins for restorative use, but not a replacement for them.

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.

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