Piezoceramic shortens root canal treatments

A new development from the Fraunhofer Institute for Ceramic Technologies and Systems IKTS should be of interest to all patients who have ever undergone root canal treatment in the dentist's chair. This is often necessary when deep-seated caries and inflammation have attacked the roots of the tooth. To save the tooth, the dentist opens the tooth and removes the inflamed tissue inside the root canal using a rotating file instrument. Even if a local anaesthetic is administered in the process: The procedure is exhausting and strenuous for both the person in the dental chair and the doctor. This is not least due to the fact that the tissue removed from the root canals adheres to the file and sticks to it.

As part of the joint research project »IPUCLEAN« (Intelligent piezoelectric ultrasonic system for increasing the cleaning and cutting performance of root canal files made of nickel-titanium alloys), researchers at Fraunhofer IKTS in Dresden have designed an innovative file instrument that makes the dentist's work easier and reduces treatment time. To this end, the team led by Dr Holger Neubert, Head of the Intelligent Materials and Systems department, has developed a tiny piezoceramic stack actuator that superimposes an axially oscillating movement in the ultrasonic frequency range on the rotation of the file.

In the classic procedure, the dental file rotates at around 200 revolutions per minute using an electric motor in the handpiece. It is inserted into the root canal and periodically moved forwards and backwards. Some of the tissue to be removed adheres to the file as a sticky mass, which reduces the cleaning performance and increases the strain on the file. Although the dental file is made of a highly elastic nickel-titanium alloy (NiTi), there is an increased risk of the file breaking under load. It must therefore always be removed and carefully rinsed.

Neubert explains the advantages of using the piezoceramic stack actuator: »By superimposing the rotation with an axial oscillation, the file clogs less quickly and therefore does not need to be rinsed as often. The dentist can concentrate much better on the already difficult work in the root canal. This also reduces the risk of file breakage for patients: The root canal treatment is over much faster.

»The basic idea of combining the two movements of the dental file came from doctors at the Faculty of Dentistry at the University of Rostock. As piezoceramic stack actuators best fulfil the special requirements in terms of vibration amplitude and frequency, the small installation space and the electrical supply voltage, we realised these as the drive element," explains Neubert. Brasseler GmbH & Co KG was the coordinator of the IPUCLEAN project funded by the German Federal Ministry of Education and Research (BMBF). Doctors from the Faculty of Dentistry at the University of Rostock have already trialled the technology on plastic teeth and given positive feedback.

Actors based on piezoceramics have several advantages. They are compact and small, work quickly and precisely, are easy to control and generate only low heat losses. In stack actuators, several layers are placed on top of each other and interconnected in such a way that the deflection of the actuator is increased. This enabled the scientists in the IPUCLEAN project to miniaturise the hand-held device so that it can still be moved easily in the confined space of the oral cavity. Another success: Fraunhofer IKTS has also produced stack actuators made of lead-free material. These already fulfil future requirements of the European RoHS Directive and are free from hazardous substances.

Further applications in medical technology

Fraunhofer IKTS is leading the way in realising the enormous potential of piezoceramic materials. The researchers have focussed on a number of other applications in medicine, such as low-frequency ultrasound transducers with high penetration depth for tomography. Thanks to miniaturisation, these piezoceramic transducers are so compact that up to 2000 pieces fit into a conventional-sized tomography system. This enables high-resolution 3D images of the human body for diagnostic purposes. High-frequency ultrasound transducers are in demand in dermatology, for example. They provide precise images with high resolution and low penetration depth. Applications as power ultrasound transducers are also possible. Here, highly focussed sound input is used to destroy tissue locally, for example in cancer therapy.

Fraunhofer IKTS will be represented at the COMPAMED medical technology trade fair in Düsseldorf at the joint Fraunhofer stand (Hall 8a, Stand G10). From 13 to 16 November 2023, visitors will be able to see the potential of piezoceramic technology for themselves with demonstrators.

Source: Press release Fraunhofer-Gesellschaft from 02 November 2023