Open your image
Make a selection of the teeth by using one of the lasso tools and/or magic wand tool
Now we’re going to refine the edge of our selection.
Go to Refine Edge or Select > Refine Edge (Alt + Ctrl +R)
Now give some Feather by sliding the slider towards the right. The amount of feather may vary depending on the size of the image and the resolution
Then click Ok
Will now turn this selection into layer mask
Make a new layer and place it under a group by pressing Ctrl + G
select the group and click on layer mask
The selection that you had will turn into layer mask
Now we’re going to tackle the color by going to the adjustment layer
Check the Colorize option & slide the Hue slider almost all the way to the left. In my case I’ve set it at 28. Adjust the saturation levels as well. In my case it’s at 25
To take the Dark areas in the teeth, go to the Adjustments Layer again, select Curves. Select the Curves Layer and double-click on it. This will open up the Layer Style dialog Box. Now Alt + Click on the Underlying Layer Slider right pointer. This will split the pointer into 2. Now move the left half of the newly created half and slide it to the right to your liking. Same with the right half, but not too much left.
Now we’ll take care of the lighter areas.
Create a new Layer inside the group. Select the Marquee tool and select the entire teeth area
Now open Edit > Fill. And fill the entire area with white
Now double-click on the recent created layer to open the Layer Style dialog box. Go to the Underlying slider & this time select the left slider arrow (the dark one) and Alt + Click to split in half. Move the right half of the pointer as far to the right as how much you need. Then do the same with the left half till you get desired results. You can also play with the opacity.
The final output!
Check this out while you wait!