Some people have a white spot(s) on a tooth or teeth. These spots can be either enamel hypoplasia or hyperpasia. Hypoplasia is more significant since it is defect in the enamel formation. The enamel doesn't form in the proper matrix and these spots are softer and can be more prone to decay if they are not kept clean. They are also more prone to become intrinsically stainned and can appear yellow, creamy or brown.
Often bleaching can help alter the appearance of teeth with these spots, since the rest of the tooth becomes lighter when bleached, so that after significant bleaching , the whitespots can become less noticable. Interestingly, when patients do first start bleaching the white spots immediately become more noticeable because they brighten faster than the rest of the surrounding tooth. hypoplastic enamel is close to the surface and more porous than the rest of the tooth.
Enamel hyperplasia can cause tiny white flecks (or brown) on teeth and can be seen often near the incisal edges or proximal sides of the teeth. These are portions of the enamel that are harder than ordinary enamel and are even more resistant to decay. These are thought to be related to fluoride intake and are more prevalent in populations taking higher doses of fluoride in their water (higher that 1ppm).