Achieving the Optimal Restorative Outcome

While it is possible to press IPS e.max lithium disilicate restorations in virtually any press furnace, the quality of the pressing may vary greatly depending on the furnace design. The EP 5000 automatically senses when the press cycle is complete to ensure that a dense, clean pressing is achieved. Unlike other pressable materials, lithium disilicate will lightly absorb some investment materials at the contacting surfaces during pressing. This reaction layer between the glass-ceramic and the investment creates a dirty bond surface that must be cleaned prior to veneering, shading, or glazing. In automatic press furnaces such as the EP 5000, this reaction layer is very light and easily removed. With press furnaces that do not automatically sense the complete filling of the mold, the user must estimate a pressing time. If this educated guess results in a pressing time that is too short, the furnace will abort the program prior to complete filling of the investment mold. If the pressing time is too long, an excessive reaction layer will develop, resulting in either heavy clean-up or in extreme cases, a pressing that is unusable.

Daniel O'Rourke, CDT, BDT, experienced this frustration firsthand when he first purchased the IPS e.max ceramic system. "I thought it would be wise to save myself the cost of the EP 5000 and use my existing pressing oven—I spent the next month dealing with incomplete pressings," says O'Rourke, owner of the Daniel O'Rourke Dental Studio in Dublin, New Hampshire. "I explained my problem to a technician friend of many years, and he had experienced the same issues until he purchased the EP 5000. I purchased the EP 5000 that same day, approximately 2 years ago, and to date have never had a mis-press."

The following case demonstrates the highly esthetic results that can be achieved when using IPS e.max Press lithium disilcate ceramic in conjunction with the EP 5000 pressing and firing furnace.

A patient presented needing three anterior crowns to restore teeth Nos. 7, 8, and 9 to improve her smile. The dental team decided the optimal restorative solution was to use three IPS e.max Press glass ceramic crowns. Demonstrating a high strength of 400 MPa, IPS e.max Press offers four levels of translucency—high translucency (HT), low translucency (LT), medium opacity (MO), and high opacity (HO)—and two ingot sizes for maximum flexibility.

The dentist prepared the teeth (Figure 4), impressed the case, and sent the impression to the laboratory for processing. In the laboratory, the technician poured the model and completed a full-contour wax-up of the crowns. The restorations were then sprued, invested, and burned out for pressing. The crowns were pressed in the EP 5000 pressing furnace, cut back for layering, and adjusted for shade (Figure 5). The technician applied layering ceramic to the crowns (Figure 6) and fired the restorations in the EP 5000 furnace. After firing, the crowns were contoured (Figure 7), stained, glazed, and fired once again in the EP 5000. Lastly, the final restorations were placed on the master cast (Figure 8), and the crowns were seated in the patient's mouth (Figure 9).

The preceding material was provided by the manufacturer. The statements and opinions contained therein are solely those of the manufacturer and not of the editors, publisher, or the Editorial Board of Inside Dental Technology. The preceding is not a warranty, endorsement, or approval for the aforementioned products or services or their effectiveness, quality, or safety on the part of Inside Dental Technology or AEGIS Communications. The publisher disclaims responsibility for any injury to persons or property resulting from any ideas or products referred to in the preceding material.

Maria Longo, DMD
Private Practice
Brookline, Massachusetts

Daniel O'Rourke, CDT, BDT
Owner/Operator
Daniel O'Rourke Dental Studio
Dublin, New Hampshire