Roya Shoffet-Yaghoubian, DDS

It seems on photo the amount of fractured incisal edge is not much, therefore I am sure, a skilled dentist can remove the old stained incisal filling out and place the new composite filling and make the line also disappear nicely

of course, whether to save or extract this tooth, all depends on multiple factors, your intention, cost, time, age and the condition of upper teeth in opposing arch... 

this tooth has large decay extending below gum line which for the purpose of restorations very likely will need crown lengthening /gum surgery after a successful root canal and a great crown could provide some years of service for you. obviously it has guarded prognosis . 

Please be aware there is multiple reason for your crown failure. The following are exact reasons to this failure

1.The substructure tooth needs to be long enough to hold a crown and if you have short clinical crown, the procedure called crown lengthening procedure gum surgery will be a great way to lengthen the short clinical crown

2.The other reason, the crown needs to be perfect fitting with sealed margin ,the crown would fail if it leaks and cement under the crown washes out and most likely will cause food and bacteria remaining under the crown and not only will end with dental decay under the crown it will cause bad mouth odor as a result of bacteria growth as well.

3.The crown tooth needs to be in perfect occlusion, if not the traumatic bite may cause loosening of the crown.

dear Patient,

1.i would recommend to get an xray make sure health of the nerve.

2.discoloration is an inherent to composite fillings/bondings so you can get the bonding redone and before hand it is good idea to get whiter brighter teeth get whitening in office and then proceed to get your bonding replaced at a later time 

3.ultimately you can always get a veneer for better esthetics result

for sure, the braces will be determined by orthodontist when to come off but it has nothing to do with your cavity . I suggest to get your filling as soon as possible