1. Capturing the case
A CAD/CAM crown starts with data: an intraoral scan or a desktop scan of the model. Three files matter — the prepared arch, the opposing arch and the bite registration. If the margin is obscured by tissue or blood in the scan, no design software can invent it, so retraction and a clean scan remain the most important clinical step.
2. Marking the margin line
In the CAD software the designer traces the finish line around the preparation. This single curve determines the seating, the emergence profile and how well the restoration closes at the cervical area. Where the scan is ambiguous, a good designer asks rather than guesses.
3. Insertion axis and cement gap
The insertion direction is set to avoid undercuts, and the cement gap and spacer values are configured for the chosen material and production method. Milled zirconia, pressed lithium disilicate and printed temporaries all need slightly different parameters.
4. Anatomy and occlusion
A tooth library proposal is adapted to the patient: cusp position, ridge direction, contact points and embrasures. Static contacts are checked against the antagonist, and dynamic movements are simulated so the restoration does not interfere in excursion.
- Proximal contacts adjusted to the neighbouring teeth
- Occlusal contacts distributed, not concentrated on one cusp
- Connector dimensions checked on bridges
- Minimum wall thickness respected for the material
5. Export and production
The finished design is exported as an STL or in the native project format so the lab can nest and mill or print it. When the file arrives production-ready, the lab spends its time on finishing and staining rather than on redesign.
Where crown designs usually fail
In practice most remakes trace back to three things: an unclear margin in the scan, occlusion checked only statically, and material thickness ignored in favour of aesthetics. Each of those is avoidable at the design stage.