Man, I live pretty close near here. The area is not that rich, it has a lot of criminal activity and most of the people there are either foreigners or descendents of foreigners. So the chance of her being from eastern europe is imho higher than her being dutch. Wish I could contribute more
BTW- Regarding the dentals. In the Netherlands children up to 18 years old can go to the dentist without having to pay. So any dutch person would take their children to a dentist. There could still be a probability that she is Dutch and her parents simply didn't know but it's unlikely. That is why they concluded that the uid is most likely a foreigner.