PORTFOLIO

The 7% of dental implants, crowns and bridges fails in the first few years after the operation. The failure of the implant is in most situations caused by malpositioning. The angle of the implant placement and the height of the implant with respect to the occlusal plane (a plane passing through the occlusal surface of the teeth) directly affect the implant load forces and pressure distribution in its different parts. The placement and the fine adjustment of the implant must be precise and controlled in order to avoid failures and long restorative actions after eventual failure. Today a device that quantitatively measures the occlusion (contact between teeth) and helps dentists in correctly positioning the dental prosthesis is still missing.

To address these issues, a team of scientists at Ecole Polytechnique Fédérale de Lausanne (EPFL), in close collaboration with medical experts from the Clinique Universitaire de Médecine Dentaire de Genève (CUMD), is developing a medical device able to analyze the dental occlusion of a patient under dental implant treatment and detect the tooth contact points and the load distribution on the dental arch in a few seconds during the implant positioning (crown sitting procedure). With such tool, professionals can act on the fine adjustment of the crown minimizing the risk of failure.

Based on a soft and bio-compatible sensor array, this device provides a fast and non-invasive solution to monitor the dental occlusion and the load distribution before, during and after dental implant treatments. Moreover, being thin and elastic, the sensor can adapt its shape to the dental morphology of the patient without any influence on dental occlusion. The use of the device could become a standard tool in dental implantology and pave the way for new diagnosis tools in maxillofacial surgery and orthodontics.

The innovativeness of our project resides in the use of stretchable electronics. Conventional electronic substrates and boards are rigid and they cannot be deformed to follow the human physiological curves and shapes. The appearance of flexible electronic substrates in the late `90s has allowed the production of bendable sensors and electrodes. However, the human body and its movements require an additional degree of freedom: electronic devices operating in close contact with the bodily geometry need to be stretchable, elastic and soft. That is particularly true in the case of dentistry, since any potential sensor to employ clinically in the mouth of patients has to be pulled, compressed and bitten while remaining fully functional. The demand for sensors of such kind by dental professionals has driven us to design an array of very thin pressure sensors that, upon patients' clenching, can provide different parameters about jaw occlusion (including dental contact points, the balance of relative forces and stability of the bite) helping dentists in their everyday clinical activities.

Concerning clinical aspects, the innovation resides in the capability of monitoring the patient occlusion with soft sensors that will not alter the physiological clench of the patient. This cannot be done with any of the technological solutions existing nowadays.

We have developed a technology that is able to evaluate the load distribution and detect the tooth contact points on the dental arch without influencing the patient occlusion. In order to achieve unprecedented resolution, we challenged the accuracy of a single stretchable sensor built with our technology (the entire array will be manufactured during this project). By mechanical testing in our laboratory, we demonstrated that our technology is able to resolve 70 kPa (which corresponds to 35 µm of sensor compression) on a single 0.5 0.5 mm2 stretchable sensor. By designing an array of such sensors to cover the dental arch, we will be able to sense the occlusal forces and distances with millimiter resolution in the occlusal plane and sub-millimiter resolution in the vertical axis (midsagittal plane). Thanks to the accuracy of our platform, professionals can evaluate the height of the crown with respect to the occlusal plane and its overall position with respect to near and antagonist teeth. Together with a software that displays the dental pressure map, our platform can drastically improve the current accuracy of prosthesis placement.

The team has developed a functional prototype during this last year, making sure with many experiments, that the technology can be used for medical devices in an industrial context.

Y/Ref.: 6.1376-PCT - Capacitive Sensor Array for Dental Occlusion Monitoring