Quality of prescription and fabrication of single-unit crowns by general dental practitioners in Wales.

The aim of this investigation was to describe the quality of prescription and fabrication of single-unit crowns by general dental practitioners in Wales. One hundred pre-piloted questionnaires were distributed to commercial laboratories in Wales with large catchment areas, and 20 pre-piloted questionnaires were distributed to the production laboratory at the Cardiff Dental Hospital. Information was collected relating to the quality of prescription and master impressions for single-unit crowns. One hundred and seven completed questionnaires were returned (response rate = 89%). Sixty per cent (n = 64) of questionnaires related to single-unit crowns being made in general practice under private funding arrangements, 30% (n = 32) were being made in general dental practice under National Health Service (public) funding arrangements and 10% (n = 11) were collected from the Dental Hospital. Polyvinylsiloxane impression material was used to record the master impression in all cases (n = 107). Plastic stock trays were used to make the master impression in 79% of cases (n = 85), metal stock trays were used in 19% of cases (n = 20) and special trays were used in 2% of cases (n = 2). Eighty-five per cent (n = 91) of master casts were considered to be adequate for crown fabrication. Less than 50% of written instructions (n = 52) were considered 'clear' and of sufficient detail to adequately specify the planned crown. In 21% of cases (n = 22), the technician had to contact the dentist for clarification of the design prior to making the crown. While the quality of impression making for single-unit crowns was of a reasonable standard, the quality of the accompanying written communication was poor and more than one-half of written instructions examined failed to meet the requirements of the European Union Medical Devices Directive.