Whiten Teeth (Bleach Teeth) in Photoshop

Note: This tutorial is done by Adobe Photoshop CS

Before and After photos

1. If you already have a suitable image for this tutorial open it in Photoshop, otherwise you can download this image. Open the image and duplicate it by pressing Ctrl+J, zoom in to the teeth and select the teeth nicely without going out to the gums. (Note: Use Quick Mask tool with Brush to make a smoother selection for better results).

2. Now go to Image>Adjustments>Desaturate or press Shift+Ctrl+U to turn the teeth to black and white.

3. Hide the selection by pressing Ctrl+H and open the Levels Dialog by pressing Ctrl+L, from Levels Dialog box move the white triangle handle to the left until you are satisfied with the results and press OK.

4. Now change the opacity of the Dublicate Layer to make the teeth look real, I have set it to 80% as shown below. You can go step further to make it look more real by applying gradient effects to the edges of the teeth, so that it blends nicely with the gum. Or you can use eraser tool to erase the edges of the teeth little bit for a nice blend.