No, dental schools won't care if you don't update them that you've just recently added that one class. It would be crucial to report to dental schools of your schedule change only in the following circumstances:
1) your cumulative GPA is lower (2.5 - 3.0 range) where you must demonstrate earning higher grade in upper division science courses and by taking a heavy load semester
2) this one Anatomy course boosts you up to a full-time student status from a part-time student status
If neither of the above circumstances pertain to you, then there's no need to update the dental school just because you've added one more class to your Fall schedule. Besides, the dental schools will see it on your final transcript when they ask you for one once they've accepted you and you're about to matriculate.
You're fine, just be sure that you earn no less than a "C-"!
OR
You can inform them, it's really up to you. It's no big deal really.