First step - choose implant type for construction in DentalDB
From exocad documentation
If you want to construct a custom abutment or a screw-retained bridge, you can choose this option in the DentalDB, see section "Defining jobs for individual teeth".
To choose the implant type on a selected tooth, unfold the combo box Implant-based?  and select "On Custom Abutment" or "Screw-retained".
|Custom Abutment||Screw Retained|
If you have scanned a model with a separate scan, unfold the combo box Scan gingiva seperately?  and select "Yes".