Invisalign

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. [http://investor.aligntech.com//ReleaseDetail.cfm?ReleaseID=290654 Align Technology Announces Fourth Quarter and Fiscal 2007 Results] ]

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. As of January 29, 2008, Align Technology has 1,307 employees worldwide, and has manufactured more than 32 million aligners. The company has 133 patentsFact|date=July 2008.

Align Technology was in a legal battle with the makers of a competing product, OrthoClear, from early 2005 until September, 2006. [http://investor.aligntech.com/litigation_OC.cfm Align Technology and OrthoClear Complete Definitive Agreement] ] 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.

Advantages and disadvantages

Advantages

The most obvious advantage of the treatment is cosmetic: the aligners are completely transparent, therefore far more difficult to detect than traditional wire and bracket braces. This makes the method particularly popular among adults who want to straighten their teeth without the look of traditional metal braces, which are commonly worn by children and adolescents. In addition, the aligners are marketed as being more comfortable than braces. [ [http://www.invisalign.com/generalapp/us/en/what/index.jsp Invisalign corporate website] . Accessed July 19, 2008] Due to the removable nature of the device, food can be consumed without the encumbrance of metallic braces.

Clinically, aligners avoid many of the side effects of traditional fixed appliances,citation
title=One hundred consecutive Invisalign cases analysed
author=Humber, PV.
journal=Aesthetic Dentistry Today
year=2008
volume=2(1)
pages=36-41
url=http://www.sohamdental.co.uk/abstract.htm] for example the effects on the gums and supporting tissues. [citation
author=Taylor MG, McGorray SP, Durrett S. et al.
title=Effect of Invisalign aligners on periodontal tissues
journal=J Dent Res
year=2003
pages=1483
url=http://iadr.confex.com/iadr/2003SanAnton/techprogram/abstract_26357.htm] Fixed appliances are known to cause the roots of teeth to shorten for most patients, [citation
author=Linge BO and Linge L
title=Apical root resorption in upper anterior teeth
journal=J Dent Res
year=1983
volume=5(3)
pages=173-183
url=http://ejo.oxfordjournals.org/cgi/content/abstract/5/3/173
doi=10.1093/ejo/5.3.17] and demineralisation or tooth decay occurs in up to 50% of patients [citation
author=Gorelick L, Geiger AM, Gwinnett AJ.
title=Incidence of white spot formation after bonding and banding
journal=Am J Orthod.
year=1982
volume=Feb;81(2)
pages=93-8
url=http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=6758594&cmd=showdetailview&indexed=google] 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. [Miller KB, (2005) [http://etd.fcla.edu/UF/UFE0010291/miller_k.pdf "A comparison of treatment impacts between Invisalign and fixed appliance therapy during the first seven days of treatment"] ]

Aligners should be removed to eat, drink, to clean the teeth, or to have them checked by the clinician. (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, [citation
title=Assessment of Orthodontic Treatment Outcomes: Early Treatment versus Late Treatment
first=Tsung-Ju|last=Hsieh
first2=Yuliya|last2=Pinskaya
first3=W. Eugene|last3=Roberts
url=http://www.angle.org/pdfserv/i0003-3219-075-02-0162.pdf
journal=Angle Orthodontist
volume=75
issue=2
pages=162-170
year=2005] while Invisalign is taking between 12-18 months.citation
title=Current Products and Practice Invisalign®: early experiences
first=L.|last=Joffe
url=http://jorthod.maneyjournals.org/cgi/reprint/30/4/348
journal=Journal of Orthodontics
volume=30
pages=348–352
year=2003] In a much smaller studycitation
title=Invisalign and Traditional Orthodontic Treatment Postretention Outcomes Compared Using the American Board of Orthodontics Objective Grading System
last=Kuncio, Daniel "et al."
url=http://www.angle.org/anglonline/?request=get-document&issn=0003-3219&volume=077&issue=05&page=0864
journal=Angle Orthodontist
volume=77
issue=5
pages=864–869
doi=10.2319/100106-398.1
year=2006] 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. [ [http://www.invisalignreview.com/#jy Invisalign corporate website] . Accessed July 19 2008]

Disadvantages

The product also has potential disadvantages: the very fact that the aligners are removable means they are not continually correcting the teeth. Unlike traditional fixed braces, they are largely dependent on a patient's habits and their consistency in wearing the aligners. The success of the Invisalign aligners is based on a patient's commitment to wear the aligners for a minimum of 20-22 hours per day, only removing them when they are eating, drinking, or brushing their teeth.

The system is also somewhat expensive, as conceded by the Align company,citation
title=Align Form 10-K
year=2006
publisher=Align Technology, Inc.
url=http://sec.edgar-online.com/2006/03/01/0001104659-06-013213/Section2.asp] and can be more expensive than traditional wire and bracket systems. This is not always the case.

The aligners must be removed for eating. They and the teeth should be cleaned before re-inserting afterwards. This can be troublesome for people who are constantly snacking and may mean the patient has to clean their teeth up to six times daily.

Because the aligners are removed for eating, they can become lost or stolen. Because the aligners must be removed for eating and re-inserted, problems occur in patients who forget to do these things. Invsialign treatment will not be successful in patients who forget to remove the inserts, who forget to re-insert them, or who lose them.

By their very nature, Invisalign aligner trays are not as proficient as fixed braces at moving teeth in the vertical dimension. Certain teeth are also 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 his or her 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. Minor symptoms such as sore throat, cough, and nausea have been reported. In more serious cases, the FDA has received reports of systemic swelling or throat pain that has extended to the upper chest and wind passages requiring emergency medical treatment and discontinuation of the Invisalign treatment.Fact|date=July 2007 While the Invisalign company provides no information except the MSDS (material safety data sheet) directly to patients or orthodontists, working through the patient's orthodontist Invisalign will make the aligners with several different materials to attempt to reduce toxic or allergic sensitivity.

Should the treatment go off track, or patients fail to keep the aligners in for the required length of time, then the next aligner in the series will not fit, and a new set of impressions and aligners will be necessary, adding to the cost.

cientific studies

In a systematic review of the literature, is published in the "Journal of the American Dental Association" in 2005,citation
title=The treatment effects of Invisalign orthodontic aligners: A systematic review
author=Lagravère M, & Flores-Mir C
journal=J Am Dent Assoc
volume=136
issue=12
pages=1724-1729
year=2005
url=http://jada.highwire.org/cgi/content/abstract/136/12/1724] 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. Since this paper, more studies about the clinical effectiveness have been published; for example in the UK, Dr Paul Humber has analyzed 100 back-to-back Invisalign cases. In the USA, Akhlaghi and colleagues compared treatment with the invisalign system with treatment with conventional braces and concluded that "conventional fixed appliances achieved better results in the treatment of Class I mild crowding malocclusions". [citation
url=http://iadr.confex.com/iadr/2007orleans/techprogram/abstract_92553.htm
last=Akhlaghi A, "et al."
title=Outcome of Invisalign and traditional orthodontic treatment using PAR index
journa;J Dent Res
volume=77
year=2007] In a comparison of outcomes between the two approaches, Kuncio "et al." reported that the Invisalign group displayed greater relapse saying "the mean alignment of the Invisalign group was superior to the Braces group before and after the retention phase, but these differences were not statistically significant. Therefore, even though the Invisalign cases relapsed more, they appear to have the same, if not better, overall alignment scores." In a larger study [citation
title=Outcome assessment of Invisalign and traditional orthodontic treatment compared with the American Board of Orthodontics objective grading system
author=Djeu G. "et al.'
journal=American Journal of Orthodontics and Dentofacial Orthopedics
volume=128
issue=3
pages=292-298
year=2005
url=http://jada.highwire.org/cgi/content/abstract/136/12/1724] 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."

Pricing

The treatment price is often the same, as or more than traditional braces. Treatment price is set by the dentist or orthodontist, although the cost of treatment varies considerably by doctor. Doctor fees are usually determined by complexity and length of treatment. In the U.S., treatments range in price from $3,500 to $7,000, depending on geographic location. For example, in northwest Ohio, the case of a patient with a mild overbite and several teeth that needed to be turned cost $5,580.00 in 2008 (for a 13-month treatment). Braces would have cost $4,500.00 (if the express treatment were available, it would have been $4,300). It is important to remember that costs vary from case to case.

In Europe, the treatment price ranges from €3,000 to €5,700, depending on case complexity and length. Medical insurance is not as common in Europe, and cosmetic treatments are generally not covered by the state-supported universal health-care systems, so the braces are usually paid for entirely by the patients. Financing is frequently available.

Treatment

An orthodontist begins by taking dental impressions, x-rays and photographs of the patient's teeth and sending them to Align Technology. The impressions are put through a CT scan from which a computer creates a three-dimensional model. Technicians then individualize the teeth in the computer model and move them to their final position as prescribed by the orthodontist. Custom software then simulates the movement of the teeth in stages. The orthodontist reviews the simulation online using Align Technology's ClinCheck via a web browser and approves or modifies the treatment. Once approved, a plastic resin aligner is manufactured for each stage of the computer simulation and shipped to the orthodontist.citation
title=An esthetic and removable orthodontic treatment option for patients: Invisalign
author=Bishop A, Womack R, and Derakhshan M. (Sep-Oct 2002).
journal=The Dental Assistant
page=14]

'Attachments' are sometimes bonded to teeth that need to be "rotated" or moved more than other teeth. Clients can expect as many as thirteen attachments. They are tooth-colored and made of a glass-like substance.

'Reproximation' is a process by which the contacts between teeth are sanded down to allow for a better fit. This may also be a part of treatment.

Average treatment time is about one yearcitation
title=A Snapshot of Invisalign|author=Humber, PV.
journal=Aesthetic Dentistry Today
year=2008
volume=2(1)
pages=85-88
url=http://www.sohamdental.co.uk/abstract.htm] , 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.'

Competition

AOA Orthodontic Laboratory develops a similar system for minor-to-moderate anterior crowding or spacing and can be cheaper than Invisalign.

Notes

References

* Align Technology, Inc. (Apr 6, 2000). "Straightening Teeth Over the Internet; Thousands of Orthodontists Use Web for First Time to Treat Patients". Press Release.
* Align Technology, Inc. (Jun 20, 2006). "NAD Refers OrthoClear Inc. to FTC". Press Release.

Bibliography

The first book devoted to the treatment technique is "The Invisalign System" by Orhan C Tuncay, published by Quintessence in July 2006, ISBN 978-1850971276. This well-illustrated volume provides an interesting and useful insight into the technology of Invisalign aligners and their clinical application.Fact|date=August 2008

External links

* [http://www.invisalign.com Invisalign Official Website]
* [http://www.braces.org American Association of Orthodontists]