Open the image.
Go to View > New View. This will open
a duplicate window of the same image.
Zoom one of the windows in very
closely on the teeth. Set the other window view to Actual Pixels (100%), so you
can see how they look actual size.
Arrange your windows so you can see
both the zoomed view and the Actual Pixels view at the same time.
Select the Dodge tool.
In the options palette select
Midtones, select exposure to about 20-25%.
Select a small, soft brush, smaller
than teeth.
Paint over the teeth with the dodge
tool, which will lighten them with each stroke. Be careful not to lighten too
much that they look artificial. Keep an eye on your progress in the Actual
Pixels window.
Be sure to save the retouched photo
in a new file.
