Hi there,
It really depends on how bad the decay is. If it is fairly superficial, the dentist can fix it and retard the decay activity thus salvaging the tooth without any impact on her adult tooth that will be replacing it in the future.
However, if there is a very deep decay, resulting in an infection of the soft tissue and the underlying tissues of the baby tooth, there is a chance that the adult may be affected since it is lying in fairly close proximity. If this is so, removing the infection is ideally the best way to minimize any bad effects on its adult tooth.
Treatment could range from an extraction or a root canal treatment. However removing the baby tooth too early could cause higher risk of misalignment as well. Thus it is best to talk to your dentist regarding the pros and cons of each treatment.
Hope this helps!
Cheers,
Kenneth
