No it doesn't. The bacteria in our mouths ferment sugars which is what causes the tooth decay.
Stevia has a different chemical structure than sugar, so the bacteria can't ferment it.
In fact, the stevia herb (I'm not sure about the extract) is included in some dental products (I like Dr. Christophers Tooth Powder). I think it's probably for the sweetness rather than for any positive effects on the teeth though.