Teeth discoloration

Hello looking for some help/advice. Recently one of my Chins had a problem with one of his eyes by keeping it closed and slight discharge around it. I took him to my local vet who checked him over and gave him a clean bill of health and said he might have just had something in his eyes and gave some eye drops, he's completely fine now.

At the time the vet checked his teeth as well and said they were healthy but I've noticed some dark discoloration at the tips and was wondering if anyone...

Teeth discoloration