While the AKC breed standard does not include a toothy picture, there was one I found attributed to the Doberman Pinscher Club of America.
A Doberman's toothy maw is supposed to contain 42 total teeth. A lot, yes? That's 6 incisors, on the top and bottom, for a total of 12. Four canines, two top, two bottom.
Also (From the Doberman Pinscher Club of America web site::
Sixteen Premolars -The upper jaw has 3 small premolars plus I large premolar (4 to aside) located behind the canines totaling 8 premolars. The lower jaw has 4 small premolars located behind the canines totaling 8 premolars.
Ten Molars - The upper jaw has 2 small molars (2 to a side) located behind the premolars totaling 4 molars. The lower jaw had I large molar plus 2 small molars (3 to a side] located behind the premolars totaling 6 molars.
The Doberman has a "scissors bite", which means the lower incisors touch the inside of the upper incisors.
Reasons a dog may be missing teeth vary, but may include things like accidents, poor nutrition, and occasionally (I hear tell), they just don't come in. According to this web site, dental x-rays can be performed as early as 10 weeks to make sure all teeth are present and accounted for. I don't know how often a breeder will do this when picking a show prospect, but I guess it would be done if there was adequate concern.