While metal bracketed orthodontic braces were voted the least attractive teeth straightening appliance, they are also considered the most effective. Clear brackets, lingual brackets, and clear orthodontic trays (like Invisalign) are more esthetic than traditional metal bracketed braces, and patients will pay hundreds of dollars more for these attractive options. However, if results are the issue, orthodontists have more control over traditional, stainless steel orthodontia. The research by Dr. Fields and James Ziuchkovski, and other colleagues was published in the American Journal of Orthodontics and Dentofacial Orthopedics.
SOURCE: http://www.sciencedaily.com/releases/2008/07/080709144136.htm