White spots on the front teeth usually happen either naturally or are caused by braces during orthodontics to straighten the teeth. It appears white because of a slight change in the structure of the outer layer of the tooth.
The first treatment that I recommend for white spots on the teeth here in my Victoria, TX dental office is to bleach the teeth. Teeth can only get so white, so if you bleach the teeth around the white spots, usually it will all blend together. During the bleaching though, these spots can appear even whiter than before because they tend to bleach more rapidly than the tooth around them.