What Could Have Caused a Tiny Hole/dent in my Skin After Botox?

I have never heard of a mark being left by a botox needle. These needles are very tiny and I can't imagine any physician using a very large diameter needle for Botox, and even those wouldn't usually leave a mark.  You might have a dilated pore that only became noticable to you recently, especially if it was in the valley of a crease and hidden until this botox treatment made the valley less deep by flattening the bulging muscles and made the pore become visible.

That can be from the needle mark and generally goes away.  Or, it might have always been there and you are just now noticing it.  It could also be a pore that is too large.  If you are really concerned, talk to your physician, but it’s probably nothing to be alarmed about. 

It is probably that you noted the dilated pore or comedone after the botox injection.  I would visit your doctor/ botox injector and share your concerns however.

The needles used for practically any skin injection are all 25 gauge or smaller.  They don't leave marks at all.  Did you have a bruise or some other area of concern there from a prior treatment.

The Botox injeections are done by small needle(30 gauge) and this will not leave any marks. Check with your doctor and most likely you had a depression before and noticed it post injection.