Method 1: Dodge

Follow the diagrammatic view to learn the same.

Fig 1: Portrait that needs  whitening of teeth & eye.

Fig 2: Pick te dodge tool from the tools menu.

Fig 3: Select midtones for the range of the didge tool and keep the exposure to 50%

Fig 4: Image treated.

Method 2: Screen mode

Follow the diagramatic view to learn the same.

Fig 1: Portrait that needs  whitening of teeth & eye.

Fig 2: Make selection of the teeth.

Fig 3: Press Cmd/Cntl+J to copy and paste the selected portion of teeth onto a new layer. Change the Mode of the layer to screen. That makes the white portion look whiter. The effect is too strong in itself, but by reducing the opacity you can control the amount of whitening effect you want.

Fig 4: Dental treatment achieved.

Method 3: Curves

Follow the diagramatic view to learn the same.

Fig 1: Portrait that needs  whitening of teeth

Fig 2: Select the teeth area with a magic wand or a pen tool.

Fig 3: Open curve dialogue box (Cmnd/Cntl+M on Mac or pc respectively). Keep the channel as RGB an drag the top right corner of the diagnol ine to the left as shown.

Fig 4: You will notice that the result is slightly yellowing. Hence change the channel to blue, as blue compliments yellow. Then create curve as shown.

Fig 5: dental teatment done.