From exocad documentation
To design the bottom of the abutment, the part which is below the gingiva, you might follow these steps.
The gingiva is displayed opaque, so that you can look through it for better design control.
|To define the opacity, right-click the part you want to change and choose 'Visual properties' in the context menu. Then choose the opacity value.|
|To choose a different shape, you can select it by using the shape buttons . To create a more convex shape, use the shape on the right or a dished shape with the left button. With the sliders  you can also control the shape: with the upper slider you can control the upper part of the abutment and with the lower one, you can control the shape of the lower part.
Free-forming abutment bottoms
Any change done using these controls applies to all abutment of the whole restoration. If you want to change only one abutment, don't use the sliders. Use the free-forming mode instead by clicking the checkbox Free-form . Left-click where you want to add material, and material will be added there.
|While holding the <SHIFT> key and left-clicking, you can remove material. Left-clicking adds material only locally. If you want to add material all around, you can hold the <CTRL> key while clicking left.|
Visualizing intersections (pressure) to the gingiva
You can also visualize intersections with the gingiva by activating the checkbox Visualize  so you can see how much pressure is applied on the gingiva or how far the distance from the gingiva is.
- Blue color indicates that there is space to the gingiva.
- Red color indicates that there is pressure on the gingiva.
You can control the scale of the visualization by moving the sliders . This is important because we need a very precise control for the pressure we want to apply on the gingiva.
We can also limit the intersection to the gingiva by activating the checkboxes . The upper checkbox is for distance control, the checkbox below is for intersection control. The distance and intersection are then controlled for all abutments by the values in the fields left from the limit checkboxes . If the values are set to zero, the emergence profile is adapted to the gingiva scan.
Control points at the border of the abutment bottom
You can drag these points  by dragging the arrows or the point itself. When using the arrows, the movement is restricted to the arrow direction. The point can be dragged freely in all directions.
If you want to create a very complex shape, it is useful to add more control points.
|To add a control point, click the margin of the emergence profile while holding <STRG>.
To remove a control point, click it, hold the left mouse button and right-click.
The toggle disk - meaning of the color
Rose-colored means that the point is attached to the gingiva.
Below each control point there is a toggle disk . Using this disk, you can change the color of the control point to green. In the green mode  the control point detached from the gingiva, and you can move it freely away from the gingiva. You can set pressure to the gingiva by intersection.
|With holding <CTRL>, you can set all points to green.||
With Height , you can define the height at the border of the abutment to the supraconstruction. The dental technician wants to have a sharp edge here. But milling a sharp edge is a problem, there are material-specific limitations, especially if you want to mill in zirconia. If the Radius slider  is set to zero, the radius of the abutment is a straight line to the implant.
Checking the Allow below implant  box will allow free-forming below the level of the implant surface - Use with caution!
The entire margin can be moved together with the Move All Margins  controls.
With Unstick all , you can detach all control points of all constructions. All control points and toggle disks switch to green. The opposite can be reached by clicking Re-stick all , so that all control points and toggle disks switch to rose color.
|You can also enforce a predefined shape either by holding <SHIFT> and clicking "Unstick all" to enforce a predefined radius, or by holding <CTRL> and clicking "Unstick all" to enforce a predefined height.||