If the soft tissue within a tooth (the pulp/nerve) becomes infected then treatment is required to remove it. The tooth root is mechanically cleaned and disinfected prior to the placement of a suitable filling material. This procedure is known as root canal treatment and is a speciality of Dentistry referred to as Endodontics. Root canal treatment is a major source of activity in dentistry with one million root fillings being placed in the General Dental Service in the year to March 2004 at a cost of 50.5 million to the country. These National Health Service figures do not take into account the endodontic work done under private contract. Any clinical technique that serves to improve the longevity of the tooth by increasing the success of the shaping and disinfection of the root canal will lead to improvements in the quality of life.Dental ultrasonic instruments are used to clean the external surface of teeth. Part of this cleaning process is by the occurrence of inertial cavitation occurring in the associated cooling water. This project aims to focus on the cavitation process and to look to maximising its ability to provide a more significant cleaning mechanism within the internal part of the tooth.Our research will be based in two centres. The University of Birmingham will evaluate the vibration performance of ultrasonic root canal files in tooth root canals (in vitro) using scanning laser vibrometry. The University of Bath will measure the occurrence of cavitation and its spatial distribution within the root canals of tooth models during ultrasonic instrumentation using newly development measuring systems such as a Cavimeter. Both teams have a strong record of collaboration and we will come together to identify those endosonic file designs that produce the optimum cavitation. We will look using both MicroCT and SEM to assess the contribution of cavitation to the cleaning process. We will develop in vitro model systems that have the potential not only to assist in the project but will lead to commercial development for the training of dentists. Our goal is to produce a set of commercially available files that may be ultrasonically activated to produce cavitation. It will be possible to predict where this cavitation occurs and then this will lead to improvements in clinical technique which will eventually bring about benefits for patients receiving such treatment.