Diagnosis and treatment of a yellow stain in front tooth since childhood

[israb]

I have this stain on my front tooth that has been there since it came out. Now, in my 20s, it is still there. Can you help me with the diagnosis and possible treatments for it.

 

[MattKW]

Molar-Incisor Hypomineralisation (MIH). More commonly seen on molars, but happens occasionally for incisors (my son has a small one). They are fairly shallow (unlike decay) - as suggested in attachment, you can try GC Tooth Mousse. Apply a dab 2-3x daily after first brushing your teeth and try not to disturb for at least 30mins. I have seen some good results that have made the white marks reduce in size, but not always completely disappear. Otherwise, it would require a drill-and-fill.