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

This maybe because of decay or the Gap me be because ofspacing between the tooth. Kindly get it checked by a dentist he or she can guide you in a proper manner. The procedure is painless and can result in good aesthetic

Hello Visit a dentist soon and get the space filled. Regards

You might require simply cosmetic filling.consult with your dentist for needful