Understanding Cement-Retained Implant Restorations

In a previous article I discussed the advantages and disadvantages of both screw-retained and cement-retained implant restorations. Although I have significantly increased the number of screw-retained restorations I am placing throughout the mouth, by far the majority of what I place in the maxillary anterior is still cement-retained.

The main advantage of cement-retained restorations in this area is that they can be done regardless of the implant angulation. However, in order to predictably cement the restoration and minimize the chance of leaving residual cement, I find that in most situations it is advisable to use a custom abutment.

The rationale for using a custom abutment is two-fold. The first reason is that the subgingival emergence profile that was created by the provisional restoration (which ultimately supports the soft tissue architecture) can be reproduced in the custom abutment almost identically if a customized impression coping is used.

The benefit of this is that we are able to maintain the support of the soft tissue that was created in the provisional phase. If the position of the soft tissue is correct with the provisional restoration and the emergence profile of the definitive abutment is different, there is a risk that the position of the soft tissue around the definitive restoration will change. If you like the position of the soft tissue with the implant provisional, a change in the tissue position may negatively impact the overall esthetics.

The second reason for using a custom abutment is it allows you to place the cement margin at a more coronal position to aid in cement removal. Traditionally, the cement margin is placed just below tissue on the facial and interproximal (0.5-1.0 mm) and at the level of the tissue palatally. However, given the esthetics of customized zirconia abutments today, we are now able to place the cement margin at the level of the tissue circumferentially without detracting from the esthetics, even if the tissue were to move apically over time.

In the posterior we typically see less soft tissue scallop from facial to interproximal and as a result, we may be able to get away without using a custom abutment. Most implant companies have “anatomic” abutments that allow you to choose from a variety of different emergence profiles, scallops and cement margin heights.

In most situations a custom abutment will still make it easier to clean cement, especially given the fact that our accessibility in the posterior can be more difficult.

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Gregg Kinzer, D.D.S., M.S., Spear Faculty and Contributing Author