Clear aligners

3D representation of a person's teeth in the Invisalign software

Treatment begins with taking x-ray and photographs for diagnostic purposes, followed by capturing the patient's bite, teeth, and gums via a bite registration and polyvinyl siloxane impressions or an intra-oral digital scanner. The latter method has greatly increased in popularity in recent years as digital scanning technology has improved. The dentist/orthodontist completes a written evaluation that includes diagnosis and treatment plan.[9][10][11][12] Dental impressions are scanned in order to create a digital 3D representation of the teeth.[10][11] Technicians move the teeth to the desired location with the program Treat, which creates the stages between the current and desired teeth positions.[11][12][13] Anywhere from six to forty-eight aligners may be needed. Each aligner moves teeth .25 to .33 millimeters.[6][9]

A computer graphic representation of the projected teeth movements, created in the software program ClinCheck, is provided to the doctor and patient for approval or modification before aligners are manufactured.[9][11][13] The aligners are modeled using CAD-CAM (computer-aided-design and computer-aided-manufacturing) software and manufactured using a rapid prototyping technique called stereolithography.[10][11] The molds for the aligners are built in layers using a photo-sensitive liquid resin that cures into a hard plastic when exposed to a laser.[10] The aligners are made from an elastic thermoplastic material that applies pressure to the teeth to move into the aligner's position.[13][14][15] Patients that need a tooth rotated or pulled down may have a small, tooth-colored[16] composite attachment bonded onto certain teeth.[13] Since the form-fitted plastic used in clear aligners is not as rigid as the metal used in traditional braces, sometimes the flexibility in the materials need to be compensated in the areas that require movement. Alternatively, attachments may be used to facilitate movement by changing the shape of the tooth.[17] More attachments can make the aligners less aesthetically pleasing.[11] Reproximation, (also called interproximal reduction or IPR and colloquially, filing or drilling), is sometimes used at the contacts between teeth to allow for a better fit.[18][19]

Each aligner is intended to be worn an optimal 22 hours a day for one to two weeks.[6] On average the treatment process takes 13.5 months,[7] although treatment time varies based on the complexity of the planned teeth movements.[6] The aligner is removed for brushing, flossing and eating. As clear aligners are made from plastic, they can be warped by hot liquids. While undergoing treatment you should limit your intake of hot liquids to protect the shape of your aligners and stop them from becoming stained.[20] Once the treatment period has concluded, the patient is advised to continue wearing a retainer at night for the foreseeable future.[21]

When the Invisalign system was first developed, many of the aligner manufacturing processes were carried out by hand, and computer technicians had to modify each tooth in the computerized model individually.[10]

Woman wearing an Invisalign clear aligner

Invisalign is manufactured by Align Technology, an American multinational medical-device company. The company's clear align system has been used to treat more than 12.2 million patients.[2] Invisalign does not use wires or brackets that require ongoing painful adjustments. Not only are the adjustments painful but the wires themselves can actually cause irritation, cuts, and nicks in your mouth.[22]

The company was founded in 1997 by Zia Chishti. Chishti conceived of the basic design of InvisAlign while an adult orthodontics patient. During his treatment with a retainer intended to complete his treatment, he posited that a series of such devices could effect a large final placement in a series of small movements.[9][10][23]

Sales began in the U.S. in 1999.[4][11]

Orthodontists were resistant to adopting Invisalign at first, in particular because the founders had no orthodontic credentials or expertise, but the product became popular among consumers.[9] As of 2014, 80,000 dentists had been trained how to use it.[4]

Zia Chishti was ousted from Align Technology in 2002. In 2005 he developed Orthoclear, a similar product, which resulted in several legal disputes involving allegations of patent infringement, false advertising, defamation and trademark infringement. The case was settled in 2006.[24][25][26] Align paid OrthoClear $20 million and OrthoClear agreed to end its operations.[25]

ClearCorrect, LLC, based in Round Rock, Texas, was established in 2006. The company distributes its product throughout the United States, and in 2011 was named the fastest-growing health company in America by Inc. magazine.[27][28] It has been reported that in 2017 its clear align system had been used to treat about 80,000 patients.[2]

ClearCorrect was founded in Houston, Texas, by Willis Pumphrey, Jr., a dentist.[29][30] In 2001, Pumphrey started using Invisalign.[24][31] He decided to switch to OrthoClear, because of the way OrthoClear manufactured its aligners and because of its reduced lab fees.[32] When manufacture of Orthoclear ceased, Pumphrey had 400 patients in treatment. With no other options available, he started his own company to complete his patients' clear aligner treatment.[33]

SmileDirectClub, based in Nashville, Tennessee, was launched in 2014 as an alternative to in-office clear aligners. The company offers direct-to-consumer clear aligner service which can be availed from home, without having to see a dentist. This allows them to price aligners at half of the other competitors. The company faces criticism from the orthodontic community because of no involvement of a physical dentist.[34] Similar startups have also launched in different parts of the world.

Following SmileDirectClub, multiple companies provide aligner treatment to patients by mailing their aligners and monitoring the treatment through a digital platform. The American Association of Orthodontists, the largest society representing orthodontists in the United States and abroad, released consumer alert explaining potential risks associated with such services.[35]

The litigious history in the clear aligner market prompted ClearCorrect to be proactive in addressing patent issues between itself and Align Technology. Align had previously filed a complaint with the U.S. International Trade Commission against OrthoClear Inc. In the end an agreement was made between Align and OrthoClear in which Align paid OrthoClear $20 million for its intellectual property and OrthoClear agreed to stop accepting cases in the United States.[24]

In 2009, Align Technology began to require that doctors prescribing Invisalign complete at least ten cases per year and ten hours of training in order to maintain their Invisalign provider status. In January 2010, 20,000 doctors had their certification suspended for not meeting the requirements, but a class action lawsuit regarding providers that paid for training under the original rules resulted in some certifications being re-instated.[36]

In February 2009, ClearCorrect filed a declaratory judgment against Align Technology. ClearCorrect claimed that some of Align's patents were invalid, and thus ClearCorrect's product did not infringe on Align’s patents.[33] ClearCorrect voluntarily dismissed the suit in April 2009, after Align stated to the court that it had no intention of suing ClearCorrect for patent infringement.[33][37]

On February 28, 2011, Align Technology filed two lawsuits against ClearCorrect. Align alleged that under California’s Unfair Practices Act, that ClearCorrect sold products for a price below the average production cost, with the purpose of "destroying competition in the market for clear aligner systems". Align also claimed that ClearCorrect infringed eight of Align's patents.[38]

On May 12, 2011, ClearCorrect filed a countersuit against Align Technology, denying allegations that it is infringing on Align patents. In the countersuit, ClearCorrect alleged that Align's allegations are invalid and accused Align of patent misuse and double patenting. The countersuit cited much of the evidence raised in Align's previous patent case against Ormco, which resulted in a federal court ruling that 11 of Align's patent claims were invalid.[39][40]