New Approaches of Planar Piezoelectric Ultrasonic Transducers for Effective Periodontal Scaling and Care

Besides dental caries, periodontitis and periimplant infections are the two most prevalent biofilm-associated oral diseases. Such chronic inflammation can cause destruction of the supporting gum tissue and eventually bone and tooth loss. To prevent oral pathologies, a professional routine for the removal of soft and hard bacterial deposits is recommended in supplement to daily oral hygiene. Manual instrumentation with curettes and ultrasonic scalers are used for prophylactic treatment. However, current ultrasonic instruments are limited in dimensions and operating frequencies. An innovative design for a novel dental scaler based on a planar ultrasonic transducer is introduced. The planar design allows the mass to be considerably reduced compared to a conventional Langevin transducer, resulting in a higher velocity to current ratio and thus an efficient but also sensitive scaler. The feasibility and potential of the planar scaler have already been confirmed by achieving displacement amplitudes of >50 μm at 28 kHz. In addition, the planar design allows for an alteration of the resonant frequency through minor geometric adjustments to the horn. The design was modified for 20 and 40 kHz to obtain information about the most advantageous operating frequency, through both electromechanical characterisation and an in vitro setup with an artificial biofilm pocket model.