Press technology: a success story

Modern all-ceramic materials such as IPS e.max set high standards in esthetic dentistry. The path to achieving this was lined by a series of research projects and inventions. Below follows a review of the eventful ride to the top.

Press ceramics: a breakthrough technology

Until the beginning of the 1990s gold alloys were considered the material of choice when incompatibility reactions on the part of the patient had to be ruled out. However, this meant that the request for a restoration that was esthetic, gentle to the natural tooth structure and free from metal could often not be met. Meanwhile, the demand for esthetic and biocompatible materials continued to grow. This provided the impetus to search for an adequate solution: Over 30 years ago, dental technician Arnold Wohlwend from the University of Zurich had the ground-breaking idea of moulding glass-ceramic in a hot state.

The wishful thinking of customers and the idea of Mister Wohlwend turned into reality in 1991. Ivoclar Vivadent achieved a breakthrough in the development of metal-free esthetic restorations: the press technology. The solution was an ingot made of leucite glass-ceramic. Pressed ceramics result in restorations that provide a very high accuracy of fit as, during the pressing procedure, the viscous (thick flowing) ceramic material flows into a mould that has been created by means of a wax pattern in the lost-wax technique.

The age of metal-free restorations

Over time, all-ceramic materials evolved into an alternative to dental alloys. Ever more patients requested highly esthetic restorations and biocompatible materials. Glass-ceramics fulfilled these requirements perfectly. And so, the press technology based on IPS Empress, the ceramic material system of the time, and the Programat press furnace, came to be seen as the state of the art. “It was not only the high strength, accuracy of fit and true-to-nature optical quality of this new glass-ceramic that made it so successful,” recalls Marcel Schweiger, Director R&D Inorganic Chemistry at Ivoclar Vivadent. “Equally decisive was the pressing process, which contributed significantly to the economic efficiency in the laboratory.” Leucite glass-ceramics, combined with the option of using an adhesive cementation technique, enabled a maximum level of esthetics and function. The passion for esthetic restorations and the incomparable feeling of seeing happily smiling patients were the driving force behind the continued further development in terms of esthetics, functionality and processing technique.

A new state-of-the-art all-ceramic material

Accepting the set benchmark as the standard was simply not an option. Rather, the aim was to further improve the esthetic and physical properties of the ceramic in line with customer needs. In 2005, Ivoclar Vivadent set the next milestone with the introduction of IPS e.max. These lithium disilicate glass-ceramic (LS₂) ingots are manufactured using especially designed processing technologies, which result in a high crystal density and provide the ceramic with excellent mechanical characteristics without impacting on its optical properties. Armin Ospelt, Senior Director of the Global Business Unit Labside Analog speaks of an exceptional press ingot: “Having a strength of 470 MPa^[1], IPS e.max Press is predestined for single-tooth restorations offering expressive esthetics. These esthetic properties are the result of the optimal interplay between the press ingot and the IPS e.max Ceram veneering ceramic, the IPS Ivocolor stains and characterization materials and the craftsmanship and esthetic sensitivity of the dental technician.”

Evolution continues

New manufacturing methods, increasing pressure on cost effectiveness and production times and the ever closer integration of laboratories and practices call for modern, efficient workflows. A coherent workflow that integrates analog press procedures with digital technologies provides a solution to these developments. The PrograPrint 3D printing system takes many time-consuming chores off the hands of the dental technician. Technical skills and a trained eye will continue to be the most important factors in giving restorations their unique individuality. Nonetheless, Armin Ospelt does not dismiss the potential of 3D printing: “The press process is made future-proof due to the increase in performance achieved with the rapid manufacturing of several wax patterns in a single printing process and the integration of the proven press technology.”

Across the world, dentists and dental technicians are using IPS e.max Pess with enthusiasm and confidence. The ceramic is also popular among patients, who love the outstanding esthetic qualities of the restorations made from it. In addition to its exceptional light optical properties, IPS e.max impresses with its excellent clinical performance: 150 million restorations placed^[4] and a survival rate of 96.2 %^[5] speak for themselves. The ten-year IPS e.max warranty inspires confidence, just like the material itself.