This picture shows the upperjaw of a dog, the M3 both sides are (still) missing.

Teeth abnormalities can be genetically induced by disturbances in the differentiation of the dental lamina and the tooth buds, and are relatively common in dogs.

Overshot: The lower jaw does not reach proper length in proportion to the upper, resulting in some degree of malocclusion.
* Bracco Italiano puppies can have a minimal overshot untill the age of 7-8 month. The lower jaw seems to grow a litle slower then the upper jaw. At the age of 12 month the overshot must has disapear.

Undershot: The lower jaw extends beyond the upper, causing some degree of malocclusion

Missing Teeth:
Dogs will lack one or more teeth, usually pre-molars.

Extra teeth:
Dogs can have extra teeth, molars or pre-molars (P). In genaral it will be the pre-molars that are extra, normally these extra pre-molars will not be a problem and do not need to removed.
But extra teeth or molars can cause problems and almost alway's a vet or dentist has to remove this elements. When this is the case it is recommended to make a x-ray first of the mouth of the dog to see if there are more problems.