When i am sick my teeth turn two different colors, the top is really yellow and the bottom is super white. why does this happen ?

Contact DDS: See your dentist, it may be as simple as a hygiene visit or the need for bleaching, must see clinically to determine.

2 visits: Make an appointment with your Dentist when you are well to document the color and color pattern of your teeth. Return to Dentist when you are sick and you perceive color change. That will enable Dentist to get a better handle on what's happening and what needs to be done, if anything.

Mouth breathing : When you are really sick and your nose is stuffy it may cause you to mouth breath. This both drys out the edges of your teeth and causes any plaque to get stickier and adhere better. Both other these reasons can cause your teeth to temporarily change color. Once you are no longer sick and are breathing through your nose again these issue resolve and your teeth return to normal color.