Conformity of removable partial denture designs from three laboratories to a set of design principles

Purpose. The purpose of this study was to assess and to compare the technical quality of removable partial dentures (RPDs) servicing both public and private sectors in relation to biomechanically acceptable principles. A convenience sample of work carried out in three commercial dental laboratories servicing both the private and government sectors was used to provide a descriptive study of the laboratory stage of fabrication of RPDs over a 3-month period. Prescription sheets, master casts and completed dentures of 114 cases were evaluated and procedural and design-related information data were captured for each case. The results were disappointing in that not one of the RPDs evaluated conformed to commonly accepted principles. Not one dentist prescribed the design of the denture. Only one cast was surveyed to determine the path of insertion and any undercuts for the placement of clasps, yet 119 clasps were placed. Although 81 rests were used (in only 25 of the dentures), only 11 of those rests were pre-prepared on the teeth. Only 8 of the 95 acrylic-based dentures had any rests, making the remainder entirely mucosa-borne and therefore potentially iatrogenic.The study suggests that principles of RPD design taught during undergraduate training are not being adequately practised in both private and public sectors; and if practised the RPDs are not designed, nor constructed to requirements guided by design principles. Further training of dental technicians and clinicians is clearly indicated, and consideration should be given to a system of clinical audit to identify and prevent the malpractice observed in this study. In addition, ethical and legal guidelines emphasising the roles of clinicians and technicians in the prescription and design of RPDs in South Africa should be developed; and the mandatory comprehensive completion of laboratory work authorisation forms by dental clinicians should be considered.