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    How to master single-unit crown procedures

    The secret to a successful single-unit crown procedure is preparation and tissue management — but that’s easier said than done.

    According to the ADA, the two most common restorative procedures in a general practice are a two-surface posterior resin and a single crown.1 Single crowns have long been the mainstay, the bread and butter, of general dental practices as the treatment of choice when full coverage is indicated.

    Several factors help determine the most appropriate type of restoration. The most important involve the size of the lesion/destruction of tooth structure and whether the remaining tooth structure must gain strength and protection from the restoration.2,3

    In many cases, the factors necessitating a full-coverage restoration are consistent with a tooth needing restoration after endodontic treatment. Given the large number of teeth that undergo root canal therapy, it’s important for restorative dentists to become proficient in this basic — and commonly needed — procedure. In fact, the single-unit crown procedure is made up of several integral procedures that when done efficiently and correctly result in an excellent treatment outcome.

    The ultimate goal for every restorative procedure in my clinical practice is to align the patient’s wants, needs and expectations with my own ability. As it relates to a crown, the patient’s expectation is simplistic: a “cap” that makes the tooth whole again, causes no discomfort, and will allow him or her to eat normally.

    Related article: Why a perfect crown may not always be the best option for a patient

    The best compliment a patient can give after a crown is completed would be, “I’ve completely forgotten it is there; it just feels like my other teeth.” This compliment might seem anticlimactic for the clinician, but it’s exactly the result we hope to achieve. A well-made restoration should mimic the natural clinical situation and when done correctly should be indistinguishable to the patient.

    The minutia of a single crown procedure, such as maintaining and facilitating gingival health, creating wide, broad contacts, or avoiding occlusal interferences, mean nothing to patients. What every dentist understands, however, is that achieving an “indistinguishable crown” is the result of properly completing all the steps of the single crown procedure. In my experience, the most important parts of the procedure involve proper preparation of the tooth as well as the creation of an ideal environment for impression-making through effective tissue management.

    PFM crowns

    Porcelain-fused-to-metal (PFM) crowns have two potential drawbacks:

    1. Veneering of feldspathic porcelain can causes abrasion, sometimes severe, of the opposing tooth.
    2. Due to the fact that PFMs are bilayered restorations, there’s a chance the weak feldspathic layer can chip or fracture and the gray metal substructure could be exposed.

    Figure 1 Occlusal view of tooth #30 showing the fractured disto-occlusal-lingual amalgamFig.1Despite the possible drawbacks of the PFM crown, it has been a stalwart in dentistry for almost 70 years. Although recently supplanted by zirconia and glass ceramics by most dental offices as the crown restoration of choice, in my 29 years of clinical practice I’ve had excellent results with PFMs, and I rarely have a case that fractures due to the bilayered construction.4

    The key to creating an indistinguishable PFM crown restoration in my experience is proper preparation. With proper reduction of the supra- as well as the sub-gingival regions of a tooth, the dental technician can develop excellent margins and life-like esthetics that highlight why the PFM restoration has stood the test of time.

    Case study

    A 60-year-old male patient presented complaining of pain from the lower right first molar. Upon clinical examination, tooth #30 was sensitive to percussion and had a fractured disto-occlusal-lingual amalgam.

    After discussion with the patient and effective local anesthesia, the existing amalgam was removed to reveal caries extending into the pulpal tissue (Fig. 1).

    Shalom Mehler, DMD
    Dr. Shalom Mehler practices in Teaneck, NJ.

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