As you are young, there problem are not common in this age group. but you may have malaligned teeth, which can be a cause of gum recession in selective teeth.
kindly visit your dentist, if possible to a periodontist for correction of gum recession. you may have to go for root canal treatment of that particular teeth and orthodontic treatment also depending upon the investigation. your dentist will be the best judge after actually seeing the tooth condition.
Wish you a healthy smile soon.
Dr Vishal jain,
Hi this is the most common problem who are having poor oral hygiene...must be due to calcific deposits on the tooth surface...visit ur dentist for proper diagnosis and treatment ...u might need professional tooth cleaning ..best of luck take care