# Using one segmentation to subtract out from another during thresholding

**URL:** <https://discourse.slicer.org/t/using-one-segmentation-to-subtract-out-from-another-during-thresholding/13978>\
**Category:** Support\
**Created:** [October 10, 2020, 6:28pm UTC](https://discourse.slicer.org/t/using-one-segmentation-to-subtract-out-from-another-during-thresholding/13978 "2020-10-10T18:28:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Stone18jo](https://avatars.discourse-cdn.com/v4/letter/s/34f0e0/32.png) [@Stone18jo](https://discourse.slicer.org/u/Stone18jo)\
**Post date:** [October 10, 2020, 6:28pm UTC](https://discourse.slicer.org/t/using-one-segmentation-to-subtract-out-from-another-during-thresholding/13978/1 "2020-10-10T18:28:00Z")

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Hello all!

I am trying to create 2 separate models for teeth that are biting together (occluding). It takes a while to isolate the lower teeth. Because they are touching, I then have to repeat the process. Instead I would like to use the lower jaw segmentation to subtract out that area on the upper jaw, to make it a faster process. On the attached photos, I want to use the cyan color to subtract out the green color. I appreciate the help!

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/0/e0cf12cb832e450ee26d53e4db56ee0b81de8f90.png)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/d/9d34504d31caae93982d427e27312299bd82e9e0.jpeg)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/c/5cf38749672d20dbf9ace184356351249c9c0004.jpeg)

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [October 10, 2020, 6:59pm UTC](https://discourse.slicer.org/t/using-one-segmentation-to-subtract-out-from-another-during-thresholding/13978/2 "2020-10-10T18:59:47Z")

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You can use “Logical operators” effect to subtract one segment from another.

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**Author:** ![Stone18jo](https://avatars.discourse-cdn.com/v4/letter/s/34f0e0/32.png) [@Stone18jo](https://discourse.slicer.org/u/Stone18jo)\
**Post date:** [October 11, 2020, 3:27pm UTC](https://discourse.slicer.org/t/using-one-segmentation-to-subtract-out-from-another-during-thresholding/13978/3 "2020-10-11T15:27:01Z")

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Thanks! This worked perfectly. Saves quite a bit of time. Take care.