Double Screw Metal technique for full arch prosthetics on divergent implants

The M2 milling units, like all other Zirkonzahn milling units, are perfectly compatible with the company's software, components and further hardware, in order to guarantee a smooth workflow from the beginning to the end of the treatment. The case described here exemplifies a smooth workflow made for a patient suffering from maxillary edentulism. Threaded channels on the metal structure were milled with the M2 Dual Wet Heavy Metal milling unit, showing the machine's high-precision milling.

The production of full-arch prosthetics on divergent implants is one of the most challenging restorations for a techno-clinical team. However, with the new Double Screw Metal technique it is now possible to produce highly stable and precise bar-supported rehabilitations even in complex cases without compromising full arch aesthetics.

In the current case, a patient presented with complete maxillary edentulism and severe left bone atrophy in the upper jaw. The virtual tooth set-up revealed a strong divergence of implants towards the vestibular area. To strike a balance between function, stability and aesthetics in the final restoration, a primary bar was integrated using the Double Screw Metal technique.

The planned restoration consisted of a titanium bar and a secondary structure in Prettau® 2 Dispersive® zirconia. The design of the primary structure incorporated an innovative CAD/CAM workflow, in which four additional screws were integrated to screw the secondary structure to the bar. The virtual position of the screws was visualised using the new Double Screw Metal function of the Zirkonzahn.Modellier design software (Attachment module), which allows the generation of virtual screw threads within the bar design. The 3D rendering provides the optimal position of the screw channel in the primary structure, as well as the ideal fit of the screw head in the superstructure. The additional threaded screw channels were then milled during the bar milling process.

After milling, the final restoration in Prettau 2 Dispersive zirconia was characterised with the ICE Stains 3D by Enrico Steger and veneered in the gingival regions with Fresco Ceramics. The titanium bar was then screwed to the implants and the secondary structure to the bar.