Teeth whitening is probably the most common of all the oral improvement techniques. It is also one of the most affordable. The dentist makes a silicone impression of a persons teeth that is taken home, along with the dental grade whitening gel. The mold is filled the with the gel and then worn over night, for several weeks, or until you achieve the desired effect. While this will improve the surface appearance of discolored teeth, more complex methods are needed to fix shape and structure problems.