Select the Zoom Tool and zoom into about 120%.

Select... Paint brush tool.

Use these settings:

Size... 15

Hardness...18

Step... 25

Density...100

Thickness... 100

Rotation... 0

Opacity... 32

Blend Mode... Lighten

Now click the Foreground Swatch then click... OK.

Paint the teeth then save... Done.

 

Congratulations!!!!

 

Note: If you have any questions let me know.