Screw hole design

Screw hole design

For the design of a screw retained bridge it can be helpful to design the screw channel extended above the actual framework. The reason for this, first of all, is an advantage during the application of ceramic which can't flow into the screw channel holes. The second reason is, that during the fixation of the bridge, the tool is better guided and canting of the the tool effects no chipping of the ceramic, which is a certain risk in that process.

The anatomy will here be presented with transparency.

We could specify an offset between the anatomy and "Height" [1] of the screw channel. You can use slider for that, or put the values in the input field. Values greater than zero makes the screw channel higher than the anatomy, values below zero shrink the screw channel lower than the anatomy.

Furtherwise we have also control points with toggle disks here. The toggle disks below the control points are black colored, which means that the control points were fixed in their height to the anatomy and the thickness is controlled default to the value by slider „Thickness“ [2].

You might want to change the thickness individually and selectively to one or more control points, then you can click on the arrow by the control point, hold the mouse button and drag it to outside from the center away to your desireable value. The minimum value is fixed by the „Thickness“ slider. If you want to increase the thickness in one direction, eg mesial/distal/oral/vestibular, then click on the arrow which you define as center of range movement at the control point, hold <SHIFT> Key pressed and drag the part of the screw channel to the desired thickness.

If you want all-over the same thickness of the screw channel, then you can click on an arrow at the control point, hold <CTRL> key pressed and drag the border of the screw channel out.



You can switch to free movement mode by clicking on the toggle disk. The color switch from black to green [1]. Now you can move this control point in all directions, only restricted by the minimal thickness.

There is also another usefull thing now available. In the middle of the screw channel appears another control point [2], which makes movement controlled in up/down direction possible. But only for the control points which are toggled to free mode.

To unlock all control points, you have to choose a locked control point, hold <CTRL> pressed while clicking on the toggle disk. Now all points change to free movement mode. You can now individually lift them to an height by dragging the green point in the middle of the screw channel as you desire. 

While pressing <CTRL> and <SHIFT> together and clicking on the big green control point in the middle of the screw channel, you can flatten the top of the screw channel.

Through clicking on the „Anatomy“ button [1], you can snap the height of the screw hole to the anatomy or through clicking on the „Framework“ button [2] you can snap the height of the screw hole to the framework. The offset value „Height“ is then in reference to the chosen mode. 

It is also possible to switch between the modes by using the toggle buttons [3] on the specific tooth in the tooth bow:

anatomy/ white colored
framework / green colored

off, no screwchannel / yellow colored

You can get a summary of all available commands by holding the mouse cursor over the blue „i“ in the little Wizard window on the left upper edge.