If stop areas like the A-line are required, the technician should prepare the model before scanning (trim material away respectively). If the A-line or other stop areas are built by the CAD system and not on the model, the basis will not fit on the model when it is printed or milled.
Nevertheless, the A-line and the butterfly zone can be defined by the CAD.
The relieve areas that are defined in this step are:
- torus palatinus (upper jaw)
- tuberculum (upper jaw)
- Trigonum retromolaris (lower jaw)
are raised by a further factor to prevent pain. These zones may need to be relieved if the patient has a thick gingival biotype.
The traditional relief zones (see graphics) are not relevant in digitally produced dentures.
As stated before the A-line and the Butterfly zone are not required when creating a denture base digitally. But considering the fact that dentists may search for it and want it, this is also added to this step.
The torus palatinum encloses the incisive papilla, which is determined in the “Alveolar Ridge” step.
All points that have been calculated until this step must be shown (provided the ability to show/hide) them.