I am 20 years old & have mild white spot on smooth surface of my tooths which i discovered recently. during checkup dentist told it was due to fluorosis so is it possible to have white spots due to fluorosis at this age?

Yes, I answered your question before. Fluorosis began in childhood with high fluoride exposure in the first 48 months of age and can manifest in adult years. BY UPTODATE: "According to data from the National Health and Nutrition Examination Survey, the prevalence of fluorosis among persons aged 6 to 39 years was 23 percent during 1999 to 2002".

The features are present in the enamel before the teeth erupt but one thing- whitening- sometimes accentuates the appearance of fluorosis. A whitening toothpaste or professional whitening may initially make the spots more noticeable but they often tone down when whitening is terminated. Severe fluorosis can make teeth brown and weaken the enamel. Sometimes well water naturally has excessive F.