Critiquing the Computer - Aided Design of Dental Prostheses

This paper describes RaPiD, a computer-aided assistant for the design of dental prostheses called removable partial dentures. The user manipulates icons directly to indicate the desired design solution to a given clinical situation. A developing design is represented as a logic database of components in a design; expert rules are applied as integrity constraints governing valid database transactions/design alterations. RaPiD has two modes of operation: manual mode designed for educational use (at either "student" or "expert" level) , and automatic, which is intended for dentists in practice. In automatic mode, the dentist enters key clinical information, after which the system takes over and completes the ''esign. Contravention of design rules is presented to the user in a critiquing style. The critiquing style strategies form the basis for the system's use in undergraduate and graduate dental education. Critiquing strategies used include: (1) a critique is issued only when the user has completed the proposed alteration; (2) a critique is issued immediately upon the user's radical misuse of a tool; (3) critiquing dynamically without negotiation with the user; (4) critiquing requested by the user upon completion of a design session, or at certain other stages in the design process; and (5) optional critiquing, requested by the user who wishes to compare his design with that which would have been produced independently by the system. An assessment of the educational effectiveness is planned. Expanding the range of design rules in RaPiD so that it becomes comprehensive is a current priority, as is the introduction of critiquing strategies (4) and (5), as well as completion of the automatic mode of operation. The extensive use and testing of RaPID, already carried out, show it to be a versatile and robust knowledge-based system. (Contains 14 references.) (Author/MAS) **) ****************************************************************** Reproductions supplied by EDRS are the best that can be made from the original document. *********************************************************************** U.S. DEPARTMENT OF EDUCATION Critiquing the computer-aided design of dental prostheses Office ol Educational Research and IrnOrovement EDUCATIONAL RESOURCES INFORMATION CENTE R (ERIC) O This document has been reproduced as received from the person Or organization originating tt C Minor changes have been made to improve reproduction (Wality Points ot view or opinOns stared in this dor, ment do nOt necessarily represent acid! OERI position or potcy F. J. Fitzpatrick', J. C. Davenport', P. Hammondu and D. A. Randell' 1The School of Dentistry, The University of Birmingham, St. Chad's Queensway, Birmingham B4 6NN, England. E-mail: [email protected]. 2Advanced Computation Lab, Imperial Cancer Research Fund, Lincoln's Inn Fields, London. Abstract: This paper describes RaPiD, an assistant for the design of dental prostheses called removable partial dentures. The user manipulates icons directly to indicate the desired design solution to a given clinical situation. A developing design is represented as a logic database of components in a design; expert rules are applied as integrity constraints governing valid database transactions/design alterations. Contravention of design rules is presented to the user in a critiquing style. e critiquing This paper describes RaPiD, an assistant for the design of dental prostheses called removable partial dentures. The user manipulates icons directly to indicate the desired design solution to a given clinical situation. A developing design is represented as a logic database of components in a design; expert rules are applied as integrity constraints governing valid database transactions/design alterations. Contravention of design rules is presented to the user in a critiquing style. e critiquing CNI strategies form the basis for the system's use in undergraduate and graduate dental education. oo oo The education of dental undergraduates includes instruction in the principles of the design of dental prostheses. C2) The design process is a complex and difficult task, and the time available in the dental curriculum to impart the required knowledge is limited. If students were to have open access to a knowledge-based system for the design of prostheses, there could be important educational benefits. Such a system, RaPiD (Removable Partial Denture design using artificial intelligence), is now being developed by specialists in prosthetic dentistry and knowledge-based systems. RaPiD is usable both as a prescription system for dental practitioners and as a teaching system which can be configured for undergraduate and postgraduate use. RaPiD as a prescription system has already been described in the dental and Al literature (Hammond et al, 1993a and 1993b); this paper concentrates on its educational use, in particular on its critiquing strategies which guide a user through a design. I. Removable partial dentures A removable partial denture (RPD) is a denture provided for a patient who has some natural teeth remaining. It enables its wearer to chew food effectively, assists speech and helps to stabilise the remaining natural teeth; it may also enhance the patient's appearance. An RPD comprises up to 40 components, the most important of which are as follows. The saddles carry the artificial teeth and fit over the area of the gum from which natural teeth are missing. Rests are metal extensions which transmit biting forces from saddles to the adjacent natural teeth. Clasps are flexible metal clips which grip natural teeth, making a denture secure during function. Finally, a major connector is a rigid metal bar or plate which unites the other components into a single prosthesis. 2. The motivation for the development of RaPiD Designing a satisfactory RPD requires clinical training and experience. The dentist should carry out a detailed assessment of the patient and of models of the patient's teeth and then draw a design to be sent to a dental technician as a prescription for the manufacture of the denture. However, general dental practitioners commonly delegate responsibility for design to technicians, whose training is inadequate to assess the clinical factors in a case. The resulting denture may fit poorly, and may even pose a threat to the patient's remaining natural teeth. The reasons for this delegation of responsibility are not entirely clear, although limited design experience may be crucial (Basker et al, 1978 and 1991). One factor which motivated the development of RaPiD was the desire to build an educational tool that could enhance the training of dental students and practitioners. A general dental practitioner in the UK designs, on average, one RPD a month, while in dental schools students may have to produce only five or six RPD designs for patients throughout their undergraduate study (Holt et al, 1993). It is doubtful whether this frequency is sufficient to ensure adequate familiarity with good design principles, whether by students or by graduate dentists. Clearly a knowledge-based system which uses a graphical interface allowing the creation of new designs and alteration of existing ones, which incorporates all the principles governing correct design of RPDs and can detect and critique attempts to violate them, could be a powerful educational tool. The evidence is, then, that a system such as RaPiD will meet a genuine and pressing need. "PERMISSION TO REPRODUCE THIS MATERIAL HAS BEEN GRANTED BY