Solidify Modifier solidifying the wrong way for only a few vertices I am  touching up a Jack O'Lantern that I made last year. I put the mouth back and manually de-solidified the thing. After I made my adjustments to the mouth and other minor things I wanted to make it a little more high poly so I added a SubSurf Mod to it. Then I naturally wanted it to be solid so I added the Solidify, but one of the carved out teeth is acting funny and solidifying the wrong way from all the rest of the mesh. I will give the file for you because this seems like a really hard problem to figure out just from pictures and an explanation.

https://www.dropbox.com/s/960ns0jtcsok1nv/Pumpkin%20StackExchange.blend?dl=0
Your normals on the offending tooth had gotten flipped somehow.  I fixed this by selecting the entire mesh and hitting Ctrl+N.  Alternatively you could have selected the individual faces and hit Ctrl+F > flip normals.

You can visualize normals in the 3D view under N menu > mesh display rollout > normals.