Most probably the filling is broken and lodged in gum due to occlusal/ chewing forces. If so, it has to be filled again and gum will heal once broken material is removed, you can try among orasore gel, rexidine m forte gel, dentogel, dologel CT etc whatever is prescribed by your dentist at that time. If filling breaks again and again, ask for capping as a Permanent solution.
As such if everything is normal then there will be no complications in removal of tooth. But if it can be saved then it's better to save your natural tooth than implanting artificial. Clinical examination is important for decision.
Dear Lybrate user,
black spot which you are mention is rampant caries. It is a type of dental caries. Maintain her oral hygiene, wash her mouth with fresh water after every milk or any other feeding. Avoid excess sugar consumption. Consult to dentist for restoration of caries, either it will increase with time and can effect other other healthy teeth.