Canine interfering with bottom lip? Canker sore?

I just noticed this last night, and is this common? It looks like his left canine is wearing a hole in his lower lip

Here is the best picture of it, among a few others:


It has that yellow/orange crusty stuff in it sometimes, and it's red around the hole. Do we need to see a dentist? I hate canker sores, so I can't imagine how needling this must be for him.

Other pictures
http://smg.photobucket.com/albums/v665/WilyWaltzer

It's definitely something that the vet needs to check out just to be sure there's no infection and treated if there is.

Looks to me like there's an abcess just above the hole and to the right - the rounded lighter area on the gum. The hole is where the abcess is draining.

Definitely needs to be seen by the vet.

Well gosh, now it looks like his right canine is doing the same thing to the lip

The picture you posted looks normal to me... All my cats have this white bump on the bottom gum where the canine hits. However, I am concerned with the crust you are talking about... If the is not food, then yes, I would see a vet...