Invisalign is a series of clear, removable teeth aligners that both orthodontists and dentists use as an alternative to traditional metal dental braces. As of April 2008, more than 730,000 patients have completed or are currently in treatment.
Invisalign is designed, manufactured, and marketed by Santa Clara-based medical-device company Align Technology, Inc. Align says that over 35,790 doctors are trained to provide Invisalign treatment in the U.S., with 48,130 doctors worldwide. Zia Chisti, one of the founders of Align, had started OrthoClear to compete against Invisalign. In a complaint filed with the United States International Trade Commission (ITC) on January 11, 2006, Align alleged that OrthoClear utilized Align's trade secrets and infringed twelve Align patents, comprising more than 200 patent claims, in the production of OrthoClear aligners at a facility in Lahore, Pakistan. On September 27, 2006, Align Technology settled its litigation with OrthoClear. OrthoClear has stopped accepting new cases and discontinued its aligner business worldwide. Align acquired all disputed intellectual property. Contrary to some reports, Align did not purchase OrthoClear.
Clinically, aligners avoid many of the side effects of traditional fixed appliances, for example the effects on the gums and supporting tissues. Almost all types of orthodontic treatment will cause the roots of teeth to shorten (root resorption) for most patients, and demineralisation or tooth decay occurs in up to 50% of patients because they cannot be removed for eating and cleaning, and because they prevent accurate x-rays from being taken. Patients "graduate" to a new set of aligners in their treatment series approximately every two weeks. The aligners give less force per week and less pain than do fixed appliances (traditional metal braces). Fixed appliances are adjusted approximately every six weeks and apply greater forces.
Aligners should be removed to eat, drink, to clean the teeth, or to have them checked by the clinician. Because you remove the aligners, you are not limited to what you eat. (It is acceptable to wear aligners while drinking water.) Computerized treatment planning is compulsory as part of the Invisalign protocol. As with other forms of orthodontic treatments that incorporate a computerized plan, this allows the prospective patient to review the projected smile design, learn how long the treatment is likely to take, compare different plans, and make a more educated decision about whether or not to use Invisalign.
Invisalign treatments have been claimed to be quicker than traditional orthodontics. A large-scale study of 408 patients with traditional appliances in Indiana took an average of 35.92 months with a maximum of 96 months, while Invisalign takes between 12–18 months. In a much smaller study Invisalign was shown to be faster and achieve straighter teeth than alternatives but relapsed to ultimately get similar results to the traditional appliances examined. The study was considered by the authors, however, to be too small for many conclusions to be statistically significant. Furthermore, this general concept that Invisalign is faster has been challenged by the Invisalign review which points out that there are other brace appliance systems that take half the time, for example by incorporating surgery or temporary implants that insert into the patient's bone, to accelerate the procedure.
The system is also somewhat expensive, as conceded by the Align company, and can be more expensive than traditional wire and bracket systems.
The aligners must be removed before eating, an advantage and disadvantage depending upon the person. They and the teeth should be cleaned before re-inserting them afterwards.
Because the aligners are removed for eating, they could be lost. Invisalign recommends that the patient keep the previous aligners in case this happens. However, Invisalign provides two plastic containers to keep the braces in, so they are safe and can't be lost or damaged.
Certain teeth are slightly problematic for Invisalign aligners to rotate. Some lower premolars with their rounded shape can be difficult for the aligners to grasp and apply a rotational force to.
Unlike traditional braces, if a patient grinds or clenches her or his teeth during the day or while sleeping, the aligners can become damaged. In practice, however, this problem is very rare and a new aligner can be ordered. Also, similar to traditional metal braces, aligners may cause a slight lisp at the beginning of treatment. This usually disappears as the patient becomes used to the treatment.
The aligners are constructed of implantable-grade polyurethane, and the Align company has acknowledged that, though extremely rare, there may be cases of allergic and toxic sensitivity reactions to Invisalign. Drs. Manual Lagravere and Carlos Flores-Mir were unable to draw strong conclusions about the effectiveness of the Invisalign system. They pointed to the need for randomized clinical trials. In a comparison of outcomes between the two approaches, Kuncio et al. Djeu and colleagues had similar findings to Akhlaghi above and concluded that "Invisalign was especially deficient in its ability to correct large anteroposterior discrepancies and occlusal contacts". They felt that "The strengths of Invisalign were its ability to close spaces and correct anterior rotations and marginal ridge heights." They added "Invisalign patients finished 4 months sooner than those with fixed appliances on average."
Furthermore, work at NYU/Buffalo University by Dr Omar Fetouh published in the ProQuest Dissertation & Theses in 2009, where 67 patients were studied, half of whom were treated with Invislaign and half with traditional braces. All cases had difficulty Index 'DI' less than 5 and were treated non extraction. The posttreatment results were graded using the ABO Objective Grading System. The results show that there was no statistical significant differences between the scores of both groups in treatment Alignment(p=0.059), Occlusal Relationship (p=0.223) and interproximal contacts. The Invisalign group had higher scores in Marginal Ridges, Bucco-lingual inclination, Occlusal contacts, and Overjet than Braces group. The study concluded that " Invisalign can treat mild cases of malocclusion (DI <5)as efficently, if not better, as braces."
In Europe, the treatment price ranges from €3,000 to €7,800, depending on case complexity and length.
'Attachments' are sometimes bonded to teeth that need to be "rotated" or moved more than other teeth. Patients can expect as many as fourteen attachments. They are tooth-colored and made of a glass-like substance.
'Reproximation' is a process by which the contacts between teeth are filed down to allow for a better fit. This may also be a part of treatment.
Average treatment time is about one year, again depending on the complexity of the treatment. Simple treatments (minor crowding, minor spacing) may be as short as twenty weeks—this is known as the "Invisalign Express" program. Although the aligners are removable, they must be worn at least 20 to 22 hours per day to avoid delaying the treatment process. If they are not worn consistently, treatment time will increase.
After the regular aligner or braces treatment is complete, retainers composed of a similar plastic material are usually required to be worn, at least at night.
Like other orthodontic systems, the patient has some flexibility. The final position of the teeth is not completely determined by the last aligner. If the patient wants to change the end position because the actual position is not optimal, new aligners are ordered, which are usually included in the originally quoted cost, called a 'Refinement.'
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