I don't think it is required for most of the dental schools.
i think it would be great to take intro to phsych (psych 101) since it is very useful and it's an easy A.
If I can remember correctly, UCLA requires one psych course.
I don't know where it is required, but it is a suggested course for many schools. I had to take PSY 101 for my major too (psych, go figure). Keep looking at those school websites, or beter yet: get the AADEA guidebook. It's worth it, and the new version is out.