/

  • linkedin
  • Increase Font
  • Sharebar

    How to streamline the cementation of crowns

    With the rise of all-ceramic restorations, it’s more important than ever to consider your cements carefully.

    Dentists, more than ever before, are able to deliver some absolutely beautiful, lifelike and well-fitting final restorations. The pendulum has swung from the predominantly porcelain-fused-to-metal market to all-ceramic restorations, driven by lithium disilicate and zirconia substrate options that offer esthetics and durability.

    Because of these materials’ dominance, it is important to look at the cements chosen for final placement, their composition and mechanisms used by which to secure the final restoration placement. Securing a final indirect restoration has moved well beyond just conventional luting or cementing.

    Gone are the days of sole reliance on mechanical retention. Adhesive cements are readily available that provide both chemical and mechanical retention. These cements allow clinicians to rely on specific adhesive features that enhance the bond strength, create an efficient workflow and provide a more confident outcome.

    Related article: 4 big benefits of resin cements

    The current landscape of cement choices is complex to navigate, and without a strong foundational knowledge of what cementation strategy to implement, cementation failures can occur. Clinical consideration must be given to the retention and resistance form of the preparation, margin placement, preparation of the intaglio surface of the restoration and adhesive cement characteristics, along with possible light curing to facilitate easier marginal and inter-proximal clean up.

    Here are some pointers to help dentists and their assistants steer through the decision-making process and determine which cement offers the best potential benefit given the clinical presentation.

    Preparation

    Begin by assessing the design, height and taper of the tooth preparation because this will determine whether the restoration needs to be cemented or bonded. The purpose of any cement is to fill the micro-gap that exists between the restoration substrate and the tooth. The cement translates the retention form of the preparation to the restoration.

    More ideal preparations permit traditional cementing options as well as allow for adhesive protocols. For those preparations that are clinically short or have a taper greater than 20 degrees, those indirect restorations will require bonding or an adhesive protocol.

    Cement choices

    Understand that modern adhesive resin cements offer versatility in how they are placed and cured. They are usually a one or two paste system, delivered in a syringe and often coined “universal cements” because they allow for the clinician to choose which of the three bonding mechanisms is appropriate given the clinical case.

    Related article: How to achieve esthetic results with direct composites

    Adhesion occurs via a total-etch method, which requires etching of the tooth accompanied by a bonding agent application; self-etch modality whereby a self-etching adhesive is applied to the tooth preparation prior to cementing; and a self-adhesive method, which is closest to traditional luting in that a bonding agent is not required.

    Light curing

    Another differential in all of these cements is their curing mechanism — some offer the ability to be light cured, while others require a dual or chemical cure. Keep in mind that light does not pass through zirconia, so when using this particular substrate, you must use a dual- or chemically-cured cement. Additionally, many of these cements feature a “wave or tack” cure of three to five seconds at the margins. Essentially, the tack cure facilitates an easier clean up around the margins while the cement is in a more gel-like phase.

    Continue to page 2 to see a case study...

    0 Comments

    Add Comment
    • No comments available