Dr. Karl Leinfelder’s brief comments on the durability of composites vs. dental amalgams ("Do Restorations Made of Amalgam Outlast Those Made of Resin-Based Composite?", August JADA) leave disturbing questions unanswered. Why does the resin "encourage the growth of microorganisms" under fillings and not under sealants?
Dr. Ronald Jordan convinced me in 1986 that sufficient research had been done to justify a switch from dental amalgams to composite in posterior teeth. It was necessary to wait another year before dentin bonding agents were available in the United States, so for about a year these restorations were placed with glass ionomer bases. However, I’ve used just composite with dentin adhesives since 1987 (no more amalgam), and there seem to be no problems with wear or recurrent caries.
Of course, crowns are still indicated in bruxers, and others are advised that that alternative is available if needed, but overall crowns are used a lot less than in the old days before dentine adhesives and good-quality posterior composites.
It seems reasonable to expect this switch from dental amalgams to bonded composites will reduce the incidence of fractured cusps, reduce periodontal disease owing to less extensive subgingival margins, and reduce the need for endodontics owing to good sealing of dentin, which has not suffered quite so much trauma to begin with.
It seems likely the real culprit, when "the rate of secondary caries associated with resin-based composite restorations is substantially higher than that associated with amalgam restorations," is the bacteriologically sloppy technique most of us settled into, knowing that we could get away with it (even before we understood how the amalgam vapors were helping us).
I challenge Dr. Leinfelder to cite a study in which cavities were prepared with rubber-dam isolation and an assist from Fusayama’s cavity-detecting dye where he can demonstrate substantially higher secondary caries. It just isn’t going to happen.
It is too bad that so many dental schools pay lip service to teaching rubber dam technique, yet so many students graduate feeling very uncomfortable and inept with this approach to operative dentistry.
