“Ouch!” – That was it: The tooth is broken. An accident, caries or simply wear and tear can put a lot of strain our natural tooth crowns. And if nothing more can be saved, an artificial crown is the last option. This is the only way to protect the tooth from further damage. Above all, we also need intact teeth to ensure our chewing function. Glass ceramics are a popular material for crowns because they are the most natural.

If an artificial crown is made, patients usually face a lengthy treatment. The dentist first examines the tooth, tooth root and tooth nerve before starting the preliminary work for the crown, the grinding of the tooth. Then he makes a jaw impression so that there is a template for the manufacture of the dental prosthesis. To bridge the gap, the patient receives a temporary solution for the next few weeks. Only then, the finished crown – which was also designed in the individual tooth color – is cemented onto the previously damaged tooth. All in all, this was a very time-consuming procedure until now.

Researchers Break Dogma

Researchers at the Fraunhofer Institute for Silicate Research ISC in Würzburg have now developed a glass ceramic for teeth that is not only high-strength, but can also be used immediately by patients. The development seems almost like a revolution in this field. Glass ceramics – consisting of an unshaped (amorphous) glass part and a composite (crystalline) ceramic part – were considered exhausted to date.

© Fraunhofer / Piotr Banczerowski

The team around Dr. Bernhard Durschang and Dr. Jörn Probst was not deterred by this. On the contrary: Together with the companies VITA Zahnfabrik H. Rauter GmbH & Co. KG and DeguDent GmbH, they broke new ground for their research. They turned upside down the previous principle of increasing the strength of a crown by pushing the crystalline phase as high as possible during production:

Instead, we have altered the properties of the glass phase – and achieved something amazing”, explains Durschang, who has been developing glasses and glass ceramics at the Fraunhofer ISC since 1996. “Adding various metal oxides to the amorphous portion increases its strength. Thus, the amorphous portion of the unpleasant residual glass, that you want to get rid of, is transformed into a useful content, that even increases the overall strength.”

Chairside Treatment

His colleague, Probst, who has been responsible for the application area of ‘Health’ at the Fraunhofer ISC since 2002, adds:

At more than 500 MPa, our glass-ceramics are significantly stronger and more robust than conventional glass-ceramics, which only reach around 350 MPa.”

Furthermore, the new material is convincing because post-curing in the furnace is no longer necessary. In addition, the glass-ceramic material has an excellent appearance, with its enamel-like translucency in all required shades. Thus, the denture can be optimally selected according to the tooth shade of the patient. And: it looks completely natural. But the best thing is that a so-called chairside treatment is possible. The patient can wait in the dentist’s chair until his new crown is inserted with only one treatment.

Award: “Technik am Menschen” (Technology for Humans)

In recognition of their research work, the Würzburg-based company was recently awarded the “Technology for Humans” prize. Every two years, the Fraunhofer Institute awards this prize for research and development work that makes a significant contribution to improving people’s quality of life. This, in turn, maintains their performance in daily life into old age. The prize is endowed with 50,000 euros.

Dr. Jörn Probst & Dr. Bernhard Durschang © Fraunhofer / Piotr Banczerowski

Long Development Time

The project ranged from the initial solution idea through material development to the CI-certified production plant. In the meantime, many dentists are already using this new type of glass ceramic. The annual turnover of these glass ceramics at the two partner companies is already in the double-digit million range – with annual growth rates of around 20 percent. Further information on this development can be found in this video.