532 BRITISH DENTAL JOURNAL, VOLUME 189, NO. 10, NOVEMBER 25 2000 PRACTICE pr osthe t ics Fig. 1 — Surveying The surveyor was first introduced to the dental profession in 1918. This instrument, which is essentially a parallelometer, is one of the cornerstones of effective RPD design and construction. The surveyor allows a vertical arm to be brought into contact with the teeth and ridges of the dental cast, thus identifying parallel surfaces and points of maximum contour. Ideally the clinician, rather than the dental technician, surveys the study cast in preparation for designing an RPD. It is this design, produced in the light of clinical knowledge and experience, which guides decisions on pre-prosthetic treatment and which is ultimately sent as a prescription to the dental technician, who constructs the denture accordingly. There are several different attachments that may be used with the surveyor. 4 Surveying This article describes the clinical objectives and procedures for surveying a dental cast prior to designing an RPD In this part, we will discuss • Surveyor attachments • Guide surfaces • Paths of insertion and displacement • Surveying sequence • Indications for tilting a cast • Positioning retentive clasps • Recording the orientation of a cast 1* Emeritus Professor, University of Birmingham, UK ; 2 Professor of Dental Prosthetics, University of Leeds and Consultant in Restorative Dentistry, Leeds Teaching Hospitals NHS Trust, Leeds, UK; 3 Honorary Research Fellow, University of Manchester (Formerly Senior Lecturer in Restorative Dentistry, University of Manchester) and Consultant in Restorative Dentistry, Central Manchester Healthcare Trust, Manchester, UK; 4 Consultant in Restorative Dentistry, Leeds Teaching Hospitals NHS Trust and Senior Clinical Lecturer, University of Leeds and Honorary Visiting Professor, Centre for Dental Services Studies, University of York, York, UK; 5 Professor of Prosthetic Dentistry, Consultant in Prosthetic Dentistry, Faculty of Odontology, University of Malmo, Sweden *Correspondence to: 5 Victoria Road, Harborne, Birmingham B17 0AG email: john.davenport@btclick.com REFEREED PAPER © British Dental Journal 2000; 189: 532–541 New publications: All the parts which comprise this series (which will be published in the BDJ) have been included (together with a number of unpublished parts) in the books A Cinical Guide to Removable Partial Dentures (ISBN 0-904588-599) and A Clinical Guide to Removable Partial Denture Design (ISBN 0-904588-637). Available from Macmillan on 01256 302699 J. C. Davenport, 1 R. M. Basker, 2 J. R. Heath, 3 J. P. Ralph, 4 and P-O. Glantz, 5 Analysing rod Fig. 2 — Analysing rod This metal rod is placed against the teeth and ridges during the initial analysis of the cast to identify undercut areas and to determine the parallelism of surfaces without marking the cast.