Nothing to worry , it might be Dental Caries and needs to be treated soon , depending on depth doctor will decide to do filling or RCT with a good cap , since she is female and involving front tooth , if doctor advise cap the My advise for you to go for Zirconia crown which gives better aesthetic appearance , if she is scared and treatment is delayed then there are chances of losing her tooth soon , also dentist cannot save the tooth if you delay for the treatment
Next Steps
Kindly visit nearby dentist soon
Health Tips
Brush twice a day , use interdental brush and floss