Dogs do not have clean mouths. Dogs are known to lick themselves, eat garbage, chew on decomposing animals and drink from toilets. However, much of the bacteria in dogs' mouths are species specific and are harmless to humans.
Dogs lick their own wounds, but this is not a treatment that cleans out an infection. A dog's tongue removes dead tissue. All that remains is the new tissue, so the wound appears to be getting healing faster.
Food adds to the bacteria inside a dog's mouth. Tartar and plaque build up on a dogs' teeth and gums causes gingivitis. Tarter and plaque may lead to bad breath, gum disease and tooth loss.