Upto the age of 16-18 years all deciduous (milk teeth) are replaced by permanent teeth. Sometimes due to more flouride in drinking water causes flourosis of teeth i. E. Yellowing of teeth. As you are 16 years old, we have check for floursis. Yellowing can also be due to plaque and calculus
deposition on the teeth. You need an oral examination by dentist
. After knowing the reason we can prescribe you treatment.