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Pressing esthetics

Creating inlay/onlay restorations using IPS e.max Press.

By Nelson Rego, CDT, AACD; Smile Designs by Rego. Dentistry by Dr. Robert G. Ritter.


Historically, dentists and laboratory technicians have been challenged to find an esthetic restorative material that offers a combination of outstanding esthetics, high strength, biocompatibility, and efficient productivity.

In recent years, metal-free lithium disilicate glass ceramic (IPS e.max Press) has demonstrated the potential to satisfy multiple requirements for laboratory ceramists and their dentists.
The versatility and performance of lithium disilicate enable laboratory ceramists to enhance productivity because the familiar lost-wax pressing techniques can be used. Additionally, lithium disilicate material can used to fabricate full-contour restorations for the posterior region. As a result, otherwise difficult combination cases can be treated with one high-strength, highly esthetic ceramic.

IPS e.max Press is indicated for inlays, onlays, thin veneers, veneers, partial crowns, anterior and posterior crowns, 3-unit anterior bridges, 3-unit premolar bridges, telescope primary crowns, and implant superstructures. When minimal tooth preparation is desired, such as for thin veneers or no-prep veneers, the IPS e.max lithium disilicate can be pressed to as thin as 0.3 mm and still demonstrates strength of 400 MPa.

Following are the laboratory procedures for using IPS e.max Press when fabricating inlay/onlay restorations for a patient who presented with failing posterior amalgam restorations (Fig. A).
IPS e.max Press material is available in MO (medium opacity), HO (high opacity), LT (low translucency), or HT (high translucency) ingots, allowing dentists and laboratory ceramists to exercise creativity in the preparation design based on the translucency of the margins. With partial preparations such as inlays and onlays, margins can be placed in the most desirable location on the tooth because the translucency of the material makes the restorations defy detection in the mouth.


THE TECHNIQUE IN PICTURES: SLIDESHOW
{refer to the slideshow for images)

Pressing Technique

The dentist follows standard preparation, impression-taking, and provisionalization protocol (Fig. B). At the laboratory, tried-and-true lost-wax techniques can be used. The model is poured from the impressions received from the dentist.

01 Perform a full-contour waxup of the restorations (Fig. C). This waxup would be similar to what would be performed for any pressed restoration.

02 Sprue the waxup onto the ringer former (Fig. D).

03 Invest the waxup, burn it out, and press the appropriately colored IPS e.max Press ingot. Note: In this case, HT (High Translucency) B1 was used to create the full-contour inlay/onlay restorations.

04 Verify the fit and contour of the pressed restorations on the model (Fig. E).

05 Fire the restorations according to the manufacturer’s instructions. Then, verify the fit of the restorations on the model.

06 Stain and glaze the restorations using the IPS e.max Shade Pastes, Essence materials, and glazes (Fig. F).

07 Fire the restorations to create a natural luster in the restoration (Fig. G). Note: When placed on a mirror, the exceptional translucency of restorations is obvious.

08 Return the restorations to the dentist, where they can be seated using conventional cementation methods or adhesive bonding protocol (Figs. H, I, J, K). 

	Features Biocompatible lithium disilicate glass ceramic Offers exceptional fit, form, function, and flexural strength (400 MPa) Kind to opposing dentition Offered in low, medium, and high opacities to meet clinical needs Lifelike esthetics independent of prepared tooth shade Allows conventional or adhesive cementation

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