Chris Scharf, owner of Espritdent, a CAD/CAM outsourcing Super Center located in Golden, Colo., has assembled the science, the material, and the manufacturing method. Scharf’s background is hardly steeped in the dental profession. For 18 years, he was involved in commercial and defense aircraft manufacturing technology, supplying customized aluminum, titanium, and ceramic part assemblies that are commonly found on 737s, 747s, C-130s, C-17s, and F-22s, typically 5-axis milled or injection-molded parts using robust CAD/CAM machines. In that business, Scharf was no stranger to material science, tight production tolerances, and customized automated manufacturing.

After September 11, 2001, however, the aircraft industry exponentially changed and Scharf was left with a new 30,000-foot facility full of expensive machinery. Unsure where to turn, he followed the advice of a dentist friend and began investigating the field of dental technology, which he had been told was rapidly converting from hand-craftsmanship to customized CAD/CAM production methods.

He ordered a market research study from the University of Colorado on the current status of the dental industry in the United States. After studying the results, he determined zirconia would be the material of choice for the future and a career opportunity existed to open an outsourcing facility to service dental laboratories with genuinely American-made substructures from the ground up.

Scharf took his years of experience in CAD/CAM technology and rapidly started working with software companies to build a solution that would create a mass customized process. In August 2004, the FDA accepted the first medical device registration from Scharf, and in 2005, he opened the doors of Espritdent for business.

“I went on a quest to develop the next-generation solution for zirconia. Our ultimate goal is to eliminate cutting tools altogether, thus eliminating material waste. As anyone who owns a CAD/CAM system knows, approximately 75% of a milled zirconia block is waste.”

Because Espritdent isostatically presses its own zirconia milling blocks, Scharf originally attempted to ball mill leftover zirconia blocks to recycle them into something usable. However, he found that the proprietary binder used to hold the zirconia powder together prevented a controlled mixture of binder to zirconia, resulting in blocks that when fired did not possess the desired density level.

Enlisting help from chemical engineers, his next attempt at creating a next-generation zirconia material looked more promising. By adding a slurry polymer binder with chemical reactants to the zirconia powder, Scharf was able to create a zirconia liquid material that could be poured into milling block molds and hardened via a chemical heat reaction.

What resulted was a plastic-like milling block that was 50% more dense than conventional pre-sintered zirconia milling blocks yet more wear kind to bur technology, increasing tool life. Controlling bur wear is critical to controlling the consistency, accuracy, and fit of each substructure milled. Once sintered, substructures made from this new zirconia block tested stronger than those milled and sintered from presintered zirconia. In the near future he plans on commercializing these blocks for the industry.

Now on the right track, Scharf realized he still had the material wastage issue because he was CAM milling these new softer blocks. He wanted to eliminate wastage by fabricating zirconia substructures without the use of milling burs.

Immediately, he began work on the last phase of material development, which was to create a liquefied zirconia that could be injection molded into customized tooth forms manufactured by advanced technology and hardened by chemical heat reaction. Colorants could be added to the liquefied material to produce tooth shades that correspond to the Vita shade guide or even customized colors that mimic gingiva or adjacent dentition.

The tooth forms are manufactured complete with sprue vents for the injection molding process. During the heat-generated hardening process, the mold material burns off, and the zirconia substructure handled conventionally, either using conventional pressing or layering techniques, once sintered.