Cat won't eat..and very small

Recently, one of my cats had to have a few teeth removed, and has eaten less and less. His usual weight is now dropped significantly, and wont eat for the life of him. Wet, dry, nothing. He has always been a, well, for lack of a better term-scardy cat. And I fear that him not eating my bring the worst. How is it possible to get him to eat even if small amounts so he may gain a few pounds..?

When was the dental done? 

Did he have a recheck/does vet know of this issue? 

Was blood work run before or after dental?

This cat needs to be seen ASAP and get to the reason all this is happening.  Many times a cat will be better then before since it hurt to eat and now don't.  Infection could be a cause.

I agree.  He definitely needs to be seen by the vet to check for infection or mouth sores.  He also might be dehydrated and need some fluids. 
 

I think a vet visit is in order. for you and kitty!