Short report on a two-year interdisciplinary development project
The idea of deep-drawn veneering was applied for a patent in 2012/2013 by ZT Marlis Eichberger and ZT Josef Schweiger (both LMU Munich) and presented for the first time in a publication in 2014 [1]. Four years later, in the current issue of Quintessenz Zahntechnik (11/2018), the team of authors reports on the successful implementation of the patent-pending veneering technology (authors: Nina Lümkemann, Marlis Eichberger, Ralph Riquier, Norbert Schuhmann, Andreas Gesewsky, Bogna Stawarczyk).
Author: Annett Kieschnick
The idea behind it
The basic idea behind the deep-drawn veneer is to replace a ceramic veneered or fully anatomical crown with a deep-drawn veneer made of thermoplastic material. The weakest link in veneered crowns and bridges - the veneer - should be replaced with a thermoplastic material and chipping should be avoided. In addition, a polymer-based veneer can provide certain cushioning properties, which could be advantageous in relation to the antagonist and the jaw joint.
The defined material requirements for deep-drawing veneers include high mechanical and thermal properties, deep-drawability, appropriate aesthetics and resistance to discoloration and abrasion. In order to meet these requirements, the development of a deep-drawable film was necessary for the veneering technology using deep-drawing technology. A polyetheretherketone (PEEK)-based thermoforming film was developed (Chair of Medical Technology at the Technical University of Munich). A special injection molding tool was constructed to produce the deep-drawing film.

Agenda
A fully anatomical framework is constructed in CAD software and an occlusal cut-back is made virtually according to the film layer thickness. Depending on the thickness of the foil, the outer contour of the tooth is virtually reduced by a defined amount and the various effects or different veneer thicknesses are individually taken into account by the software. The framework data set reflects the exact occlusal morphology (reduced size) and is milled from zirconium oxide. The reduced morphology now provides the basis for deep drawing the PEEK film. After the framework and deep-drawn veneer have been worked out, they are bonded with a chemically hardening, adhesive bonding composite.

Results after two years
The procedure was developed over a period of two years within an interdisciplinary project team of scientists, dental technologists and dental technicians and was funded by AiF eV as part of a ZIM cooperation project (ZF4052001MU5). In addition to the Materials Science Department of Dental Prosthetics at the LMU, the Medical Technology Chair of the Technical University of Munich, Dreve and Pagoda Systems also participated in the cooperation project. Looking back at the past period and the results achieved, the team reports overall that the implementation was successful. The entire process for producing an occlusally reduced zirconium oxide framework, which is veneered with the biocompatible high-performance thermoplastic PEEK using deep-drawing technology, was implemented in an interdisciplinary collaboration. The technology is currently not yet available for everyday use in a dental laboratory, but can be considered a good basis for further development ideas and research projects.
[1] Eichberger M, Edelhoff D, Schäfer J, Schweiger J, Stawarczyk B. The deep-drawn veneer. Quintessenz Dental Technology 2014;40:548-569