IPS e.max Press Lithium Disilicate Case Study:
A Full-Coverage Crown

A 32 year old female presents with a fractured posterior tooth requiring a full coverage crown (Figs. 1 and 2). The tooth is prepared with a required 1.5mm axial reduction, and a 2mm occlusal reduction (Figs. 3 and 4).  It is ideal to have an axial margin of 1mm or greater, as well as a coronal length of at least 4mm. The margin is left slightly supragingival. 

"Steve Austin, a man barely alive….. we can rebuild him.   Better than he was before.  Better, stronger, faster”.  I can still remember being a kid and staying up late on a Friday night to watch the Six Million Dollar man come alive.  The opening lines of the show still etched in my mind, as I bet it may have been etched in yours--Better, Stronger, Faster.              Have your restorations over the years become Better, Stronger, Faster?  Is the PFM still your restoration of choice?  Are early failures of all ceramic crowns in the posterior segment stopping you from prescribing them when warranted?   In dentistry we have many choices in materials for our patients posterior restorations.  As the esthetic demand from our patients increases, many dentists are left wondering how we can satisfy these demands without scarifying strength, and more importantly without increasing the difficulty or time of the procedure.  With the many types of ingots available, including the new high translucency, IPS e.max Press lithium disilicate offers me the ability to exceed my patients’ expectations for natural looking metal free restorations.  With a flexural strength of 440-Mpa it offers both esthetic and strength capabilities for the anterior and posterior segment.  These restorations can be fabricated with full conventional preparations or as thin as .3mm restorations.  Due to the materials single press construction, the strength of Emax press has shown to exceed that of porcelain to zirconia restorations where the layering porcelain is far weaker than the zirconia core.               The esthetics of lithium disilicate materials allow you to achieve better results than conventional PFM and many all ceramic restorations.   This will allow us to meet the esthetic demands of our patients today in both the anterior and posterior regions.               With the ability to keep our margins supragingival should allow us for an easier and more predictable impression technique.  In combination with the lithium disilicate materials conventional cementation technique should allow for a faster overall preparation and seat appointment.

Impressions are taken and sent to the lab with the prescription for a full-coverage IPS e.max Press lithium disilicate crown.

Delivery appointment

1. The restoration is reviewed to ensure color match, esthetic appearance, contacts, marginal integrity and occlusion on the working models (Fig. 5).
2. The temporary is removed, the preparation is cleaned of any residual temporary cement, and the final restoration is verified for fit.
3. Once the restoration is cleared for insertion, it is removed from the mouth and acid etched.  Rinse, dry and silane the restoration for 1 minute and dried.
4. Multilink primers A and B are mixed and applied to the preparation for 15 seconds.  The primer is air dried for 5 seconds.
5. Multilink Automix Universal Adhesive Cement is mixed and dispensed into the restoration (Fig. 6).
6. The restoration is seated, excess cement will extrude from the margins.
7. The cement is spot tacked into place for 3-5 seconds and the excess cement is removed from the margins.  Floss interproximally to remove any excess cement prior to final set or cure.  Cure for an additional 10 seconds.
8. Allow the restoration to self-cure for an additional 5 minutes.  The margins can then be finished with a fluted carbide burr.  The occlusion is verified and adjustments made if necessary.
9. The restoration is finally polished if adjustments were made using intra-oral porcelain polishing cups or points. Figs. 7 and 8 show the post-op facial and occlusal views respectively.