According to Bob Miller, CDT, Director of CAD/CAM and Ceramics for Zahn Dental, the Dental Wings Operating System (DWOS) also has a built-in anatomy library for occlusion for each tooth, and labs soon will be able to scan in their own occlusions to add to the library.

One of Grubb’s favorite features of his wax printer is that it allows him to do the wax design work during the day, set the machine, and come back the next morning with 100-plus units ready to invest and press. He added that the system even lets him place a case number label next to the wax coping for easy identification of the individual units.

However, Grubb doesn’t discount the benefit of a knowledgeable waxer on staff. “You can count on the printer for 95% of the waxing work, but you’re always going to need someone if the machine goes down or you have a complex case or a rush case.”

In addition, labs that can’t justify the expense of a wax CAD/CAM printer have the option of outsourcing the production of the printed forms just as they would outsource a zirconia milled coping.


SPLITTING, THE DIFFERENCE

For cases that involve pressing to a metal or zirconia framework for additional structural support, digital designing offers an advantage well beyond what is possible with hand waxing.

Traditional press-to-metal cases involve double waxups for the coping or bridge framework itself and then for the pressed form to go on top, in addition to twice the spruing, investing, etc. Conventional pressing to zirconia necessitates the fabrication of the milled substructure even before the wax portion of the pressing procedure could begin.

That is soon to change with digital systems such as Zahn’s DWOS or Weiland’s Zeno. Using these two systems, the technician can scan the prepared die, design the press-to restoration to full anatomy, then the software automatically splits the file into the separate parts needed for fabrication, including allowing for the proper space for cement (see “Splitting image” on page 15). The framework design file goes to the CAM machine, whether it’s for milled zirconia or laser-sintered metal, and the other file goes to a wax CAM machine to generate the wax form for overpressing. The two structures are created simultaneously, then are matched together back at the lab, pressed, and finished.

Smaller labs now need only to invest in a digital scanner to increase their pressing options, outsourcing both parts of a press-over restoration, then completing the case just a few days after electronically transmitting the design data to the outsource provider.

“You can mill and print and receive them at the same time,” said Miller, who also is President of CMC Custom Milling Centers. “Put the top on the bottom, invest, press. Boom, you’re done.”

Although the production area of pressable restorations is experiencing a new look from technology developers—though Laingchild feels that the zirconia and milling equipment side of CAD/CAM gets more R&D attention—it should be pointed out that pressable material represents a different type of restoration, strong and singly esthetic.

“The advent of pressing technology was the biggest single catalyst for esthetic dentistry,” said Laingchild. “Before pressing, we made the framework and hoped it would fit within the esthetic zone and then compromise the esthetics to accommodate the framework. When we went to pressing, our restoration had a full-contour concept to it. It wasn’t based on a framework. The thought process with pressing starts at full contour and works its way backwards. Whereas, the other starts at the framework and comes to meet the full contour.” 

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