In a recent discussion board thread, a dentist was wondering if it ever makes a difference exactly where you draw the lines to trim the model and mark the gingiva for an implant restoration. IOW, if the trim line is closer or farther away from the ScanBody and whether it is inside, outside or crosses over the line outlining the gingiva, does any of that matter?

Dr. Mike Skramstad answered this way a created a great video:

Here are the general rules for this:

• Trim has no affect on base line proposal if you are using Gingiva Mask when clicking on ScanBody head
• Trim has no affect on initial emergence profile if you are using Gingiva Mask when clicking on ScanBody head
• When using Gingiva Mask when clicking on ScanBody head, the emergence will follow the Gingiva Mask.  It makes no sense to draw a large line outside of it.  You will only make matters worse.  Follow whatever the shape is of the tissue.
• It doesn’t matter where you click on the ScanBody head, the base line proposal is the same
• Model Axis is the most important. It controls axis of trim. 
• The axis of the trim (not the trim itself) controls the base line proposal (both when using and not using Gingiva Mask).
• Trim DOES affect the mesial distal base line extensions if you are NOT using Gingiva Mask when clicking on ScanBody head
• Trim DOES NOT affect the buccal lingual extension of the base line when NOT using Gingiva Mask when clicking on ScanBody head.  Therefore it makes no sense to anatomically trim the buccal or lingual

These are the rules... write them down :-)

This will explain all you need to know:

https://www.cerecdoctors.com/digital-learning/view/id/1590