My 7-year old girl has her front permanent teeth turning into black on the back, is that a serious problem? What should we do in terms of treatment and perventing further deep blackening? Thank you!

Hello jiangting

We have 2 types of tooth discolorations

First 1 : external stains... and this type we can remove it by simple polishing and scaling .

Second 1 : internal stains... this type caused by systemic factors ( like flourosis stains ) and we treat this type by bleaching or veneer layer

You should to visit a dental clinic to determine stain type .