The metal framework is the foundation of every implant overdenture. Whether milled from a solid block or cast using traditional techniques, the design principles determine long-term success.
Milled Bars
Milled titanium bars offer superior precision with passive fit verified to within 10-20 microns. The milling process eliminates casting shrinkage and porosity. Milled bars are indicated for full arch cases where passive fit is critical and for patients with metal allergies (titanium is hypoallergenic).
Cast Frameworks
Cast chrome-cobalt frameworks remain cost-effective for conventional partial dentures. Modern induction casting produces frameworks with acceptable fit for non-implant applications. However, casting shrinkage of 1.5-2% makes passive fit on multiple implants challenging without sectioning and soldering.
Design Parameters
- Minimum cross-section: 4mm vertical, 3mm horizontal for titanium
- Finish line design: Chamfer or shoulder for predictable cementation
- Attachment selection: Locator, ball, or bar-clip based on retention needs