Similar to the CT converter step, teeth can be marked and defined (segmented) as independent and annotated 3D objects from the X-ray data. In order to segment teeth, the areas containing the teeth are 'colored' or marked on the CT data to define the regions which should be included in the tooth object.
Erase color from a tooth segmentation
Difference between smart and simple tools
A tooth is defined using a smart 3D brush tool (the Magic mark fill icon
) or a simple 3D brush tool (the Mark brush icon 
). When the left mouse button is pressed on CT data, the region corresponding to the clicked position is marked to be added to the tooth. The smart brush colors parts of the tooth with a similar gray value adjacent to the clicked point.
To mark a tooth:
1. First do one of the following:
— Click the Magic mark fill icon in the Mark group of the Annotate Tooth toolbar to work with the smart brush tool.
— Click the Mark brush icon in the Erase group of the Annotate Tooth toolbar to work with the simple brush tool. Alternatively, press M on the keyboard.
Note
When pressing the Mark shortcut key (M), the tool remains in the mode it was previously in. In other words, when the Annotate Tooth action is in 'smart mode' - with the upper icon selected - it will remain in smart mode when switching between the Mark or Erase tools by using the shortcut keys.
2. Scroll through the CT slices and click to mark the bone bit by bit or keep it pressed down and drag to color the bone to mark it. All data in a sphere around the clicked position is marked to be added to the tooth. Apply and verify these actions in both axial and perpendicular reslice to ensure the whole tooth is completely colored as intended.
If too much color was applied to a tooth segmentation, it can be erased using the Annotate tooth action. .
To erase color from the tooth segmentation:
1. Do one of the following:
— Click the Magic Eraser 
in the Erase group of the Annotate Tooth toolbar. Alternatively, press E on the keyboard.
— Click the Eraser 
in the Erase group of the Annotate Tooth toolbar.
2. Press the left mouse button on the CT data or keep it pressed down to erase the color to be removed from the tooth segmentation. All data in a sphere around the clicked position is removed.
Tip
The brush settings might not be suitable in specific cases. To change these settings refere to the Tool settings section.
To create the virtual annotated tooth, check whether the correct regions are marked. Click Update 3D 
in the Create Tooth group on the Annotate Tooth action page. Alternatively, press U on the keyboard.
A preview of the segmented tooth is displayed at the left hand side of the screen and is incorporated in the 3D bone model.