I am seeking out ideas for why the darkened areasof this .gltf behave so differently with lighting than the other surfaces. Specifically the lower molars, and the tongue facing surfaces of the lower incisors.

I have attempted substituting the materials of each tooth (they each use a different one with seemingly identical properties) and it has no effect. I have attempted transposing the various elements around incase it is a shadow or a lighting issue and it has no effect. This is my first blender project and I am at quite a loss.

What is most perplexing of all to me is that the tongue facing surfaces of the canines do not exhibit this behavior.

For this file, I would like each tooth surface to render with identical lighting; this model is being used to exhibit research results on the spatial positioning of childhood tooth decay, by updating the texture and material of the teeth accordingly.

Thank you so much for your assistance.

the file itself can be found here if it would aid your investigation, https://drive.google.com/file/d/1DCN1bfNcfQFS2YS195rX1iaaQRdxRrIb/view?usp=sharing

Example of lighting anomaly

  • 1
    $\begingroup$ Maybe flipped normals? Go to your Viewport Overlays, and turn on "face orientation" to see what's going on, or select all in edit mode and select mesh > normals > recalculate-outside $\endgroup$ Jan 27, 2021 at 3:03

1 Answer 1


Many of the objects have custom split normals data that need to be removed. This is fairly common with objects imported from other software, and is good to check when running into any shading issues with imported objects that aren't simply resolved.

To fix, simply go to Object Data>Geometry Data>Clear Custom Split Normals for each problem object. To speed up the process, you could use ⇧ Shift + R after selecting the next tooth to repeat the last operator. See the gif below for an example:

enter image description here


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .