A logic-based model of prosthesis design

RaPiD (J.C. Davenport et al., 1994) uses ideas from logic databases, declarative graphics and critiquing, together with expert design knowledge, to provide a CAD style graphical interface for both instructional and professional design of a dental prosthesis called a removable partial denture (RPD). An RPD is a prosthesis for replacing missing teeth and related tissues. It restores the patient´s appearance, improves speech, assists mastication and maintains a healthy, stable relationship between the remaining natural teeth. The design of RPDs requires a detailed knowledge of design principles and clinical factors. It should therefore be carried out by a dentist after a careful analysis of the patient´s oral condition and plaster models of the patient´s jaws. The resulting design is recorded as a diagram (annotated manually) and supplied to a dental technician to guide manufacture. In England and Wales, provision of RPDs increased from 228000 in 1949 to 682000 in 1994 at a cost in that year of £50M. Although the design of RPDs is a clinical responsibility, there is evidence from the USA, Australia, Scandinavia and the UK that it is frequently delegated by dentists to dental technicians who do not have appropriate clinical training. Poor RPD design results in failure of treatment and damage to oral tissues. An improvement in this unsatisfactory situation through the use of a knowledge based system to make design more compliant with best practice could be cost effective and improve quality of health care