I think that molars overgrown can affect the eyes watering but it could be a watery discharge. As far as I know the white gunk is pus indicating infection.
My rabbit beau had a lot of teeth pulled several months ago and now has an infected eye on the opposing side of the teeth extractions .
he has a corneal ulcer and has had pus in that eye.
Right now I cannot help but make a relationshop between the massive dental surgery and his eye problem but I really have evidence to support that other than it is strange timing....
If your bun has pus in his eye he has an infection somewhere.