Specifics in Production of Fixed Partial Dentures Using 3D Printed Cast Patterns

Present paper deals with the specifics in production of fixed partial dentures (FPD) using 3D printed cast patterns. The cast patterns of four-part dental bridges were manufactured of polymer NextDent Cast using RapidShape D30 printer. Two cases of application of cast patterns were discussed - for production of press-ceramic and metallic constructions. The metallic samples were cast by centrifugal casting of Co-Cr and Ni-Cr dental alloys using different investment materials and heating regimes of the casting mold. The dimensions of polymeric cast patterns and cast bridges were measured. It was established that for production of FPD with high accuracy and high adhesion of porcelain coating, precise cast patterns should be manufactured by 3D printing. The dimensions of virtual model should be corrected with coefficients, specific for each axis. The increased roughness of 3D printed cast patterns is disadvantage in dental constructions with high smoothness requirements and advantage for metal-ceramic FPD. Therefore, the position of patterns with respect to the building direction should be different for FPD of press-ceramics and cast infrastructures for metal-ceramics. In the first, vertical axes of teeth must be parallel to the print direction Z-axis, and in the second, they have to be at an angle between 45 degrees-70 degrees to the base. For ensuring high adhesion strength of porcelain coating in metal-ceramic restorations, surface smoothing operations should not be applied to 3D printed cast patterns. The revealed specifics would be very useful in dental practice for manufacturing of accurate FPD using 3D printed cast patterns.