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Invisalign®, an innovative invisible orthodontic appliance to correct malocclusions: advantages and limitations

From Volume 39, Issue 4, May 2012 | Pages 254-260

Authors

Shaymaa Abdulreda AH Ali

BDS

MClinDent Orthod, MOrth RCSedi, Specialist, Orthodontics section, Hamad Medical Corporation, Doha-Qatar, PO Box 3050

Articles by Shaymaa Abdulreda AH Ali

Henno Rainer Miethke

DrmedDent, Fachzahnarzt für Kieferorthopädie, PhD

Senior Consultant, Chairman, Dental Department, Hamad Medical Corporation, Doha-Qatar, PO Box 3050

Articles by Henno Rainer Miethke

Abstract

Tooth movement may be achieved by the use of sequential positioners made by altering tooth positions on set-up models to simulate progress of treatment. The principle is based upon Kesling's positioner concept of 1945, though its subsequent application to splint therapy was labour intensive and did not result in precise tooth movement. Invisalign® was developed by Align Technology, Inc (Santa Clara, CA, USA) in 1997 by applying 3-D imaging technology to overcome these problems, and permitting customization on a large scale. Their system offers significant advantages, but still suffers from limitations which are discussed in this article.

Clinical Relevance: By providing an aesthetic means of correcting malocclusions of minor to moderate severity, Invisalign® has met with high patient acceptance. Aggressive marketing of the system makes it essential that the orthodontists and dentists understand the basic mechanism whereby the system works, along with its strengths and limitations.

Article

Kesling's positioner was a precursor to the aligner. In 1945, Kesling foresaw the future development when he stated that:

Major tooth movements could be accomplished with a series of positioners by changing the teeth on the setup slightly, as treatment progresses. At present this type of treatment does not seem to be practical. It remains a possibility, however, and the technique for its practical application might be developed in the future.1

The following decades were characterized by aligner-like thermoformed splints which were fabricated from different acrylics, and covered all teeth as well as the marginal parts of the alveolus. However, the utilization of these splints suffered from two disadvantages. First, they were labour intensive and second, the amount of tooth movement had to be very limited to avoid excessive tooth mobility. Sheridan, later on, broadened the use of vacuum-formed aligners after the widespread introduction of his air-rotor stripping.2 By blocking out and grinding areas on the working cast, cutting windows in the appliance, thermoforming the material with special pliers, placing composite mounds on teeth and attaching elastic traction to these mounds, he managed to expand the spectrum of tooth movement. However, all this still required extensive and expensive laboratory labour.

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