For some dental clinics, intra-oral scanning to create a digital rather than physical impression of a patient’s dentition is but the first stage of an in-house production of a crown, bridge or inlay. While many dentists send the digital impression to a dental technician with a purchase order for the required prosthesis, chairside manufacture offers the advantage of one-session treatment and the close involvement of the dentist in producing the prosthesis. In some ways, it is a return to olden days, especially in country districts where a dentist made prostheses for patients.
Today, however, the manufacture of medical devices is a highly regulated activity. In Europe, the Medical Device Directive (MDD) places requirements, albeit mild ones, on the manufacturers of custom-made devices. In a recent article*, NIOM senior scientist John Tibballs and colleague Bjørn Einar Dahl from the Faculty of Dentistry, University of Oslo explored the ramifications of the MDD for CAD/CAM in the dental surgery.
As its full name, Computer-Aided Design and Manufacturing, suggests, dental CAD/CAM has two stages. After a satisfactory digital impression has been obtained, design software presents the dentist with a rotatable screen image of the prepared dentition together with a suggested shape for the dental appliance. This design can, within limits, be modified. When and if the dentist is satisfied and has selected the material to be used, the software generates manufacturing instructions. These pass to a milling machine that shapes a ceramic or alloy block. For many materials, the final step is sintering in a high-temperature furnace.
One requirement that the MDD places on the manufacturer of custom-made devices is a skeletal system for quality improvement. To aid the dental clinic in establishing a modicum of quality management, NIOM, with funding from the Norwegian Directorate of Health, is preparing a workbook, initially in Norwegian, called “CAD/CAM på tannlegekontoret” (CAD/CAM in the dental clinic). Publication is planned for early autumn. An English version will appear later.
* Odontologi 2015, P. Holmstrup (ed), pp. 141–153, Munksgaard, Copenhagen. An English translation of the text is available. Send an email to firstname.lastname@example.org.