Clear Aligner Technique: Bringing Orthodontic Treatment into the Digital Era

Reading time: 13 minutes

When clear aligners were first released to the market in 1999, most clinicians understood them to be limited to the orthodontic treatment of Class I cases with minor crowding. While they presented as an esthetic treatment option for these minor correction cases, they did not claim significant territory overall from traditional fixed appliances due to their perceived treatment limitations. However, recent advances in digital technology in dentistry have resulted in explosive improvements in clear aligner technology, and these developments have brought the technology in line with the capabilities of fixed appliances. Clear Aligner Technique, a new clinical orthodontic textbook by Sandra Tai, BDS, MS, examines clear aligner treatment from this new perspective—that clear aligner technology is a comprehensive treatment modality that can both satisfy current clinical expectations and propel the field to new heights of success.

Modern Orthodontics and the Rise of Clear Aligner Technology

Since the 1970s, the fixed straight-wire edgewise appliance has held its place as the standard treatment in modern orthodontics. However, almost immediately after this technology was achieved, innovation shifted toward improving the esthetics of orthodontic treatment. Many possible solutions have been explored, including lingual and ceramic brackets. But the motivation behind the shift from brackets to clear aligner technology isn’t limited to esthetics: The presence of fixed brackets on the teeth, whether metal or ceramic, lingual or buccal, presents meaningful issues regarding oral hygiene and patient comfort. In 1997, all three of these needs were addressed by the invention of a customized clear aligner system: Invisalign by Align Technology. This new technology revolutionized the world of dentistry and orthodontics.

“There is a distinct difference between evolutionary change and revolutionary change,” Dr Sandra Tai explains. “Evolutionary change comprises incremental changes that take place gradually over time. The evolution of fixed appliances represents variations and incremental improvements on a bracket and wire system that has taken place over the last 100 years. Revolutionary change, in contrast, is transformational change. Revolutionary change is profound, dramatic, and disruptive. Revolutionary change challenges conventional thinking and requires a radical paradigm shift in our mindset. Clear aligner technology represents a revolutionary, transformational change in orthodontics that challenges the conventional thinking of how orthodontists move teeth.

“However,” she continues, “the advent of clear aligner technology does not mean that 150 years of orthodontic principles are no longer valid. The time-tested principles and concepts of bone biology, biomechanics, anchorage, and occlusion still apply. The challenge in this 21st century of digital technology is that the clinician must now learn to apply those principles of orthodontics to the field of clear aligner technique.”

There are also significant differences between techniques for fixed appliances and aligners that clinicians must understand. “One fundamental difference,” Dr Tai explains, “is between the way a bracket and wire system moves teeth and the way clear aligners move teeth. Fixed appliances pull on teeth while clear aligners push teeth. In the illustration below, you can see that when an archwire is engaged onto a lingually erupted tooth, the elasticity in the archwire causes the archwire to return to its original arch form. As the archwire returns to its original shape, it pulls on the lingually erupted tooth to move it into the arch. The force applied to the tooth is dependent on the flexibility of the archwire and the amount of deflection it undergoes to engage the tooth. In contrast, clear aligners move teeth by exerting a push force. When an aligner is inserted over teeth, there are minor differences between the positions of the teeth intraorally and the positions of the teeth in the aligner. The aligner deforms over the teeth, and the elasticity in the aligner material pushes the teeth into position. Optimized attachments provide an active, flat surface that the aligner may push against to effect tooth movements such as extrusion or rotation.

“When making the decision as to what orthodontic appliance is best suited to resolve a malocclusion,” Dr Tai continues, “the clinician should be aware that the decision is not a matter of choosing between an esthetic appliance and an unesthetic appliance. The choice is not between two different materials of plastic versus metal. It is a decision between different mechanisms of action to move teeth. Traditionally, orthodontists are trained to be reactive. An adjustment is made to the appliance and, based on the patient’s treatment response and the resultant tooth movement, another treatment decision is made at the next appointment and the archwire adjusted accordingly. Each treatment decision is made reactively, based on the treatment response to the adjustment to the orthodontic appliance made previously. Clear aligner technique requires a more proactive, disciplined approach. Before a single tooth is moved, the correction of the malocclusion is visualized through a series of tooth movements made on a software program and the final occlusion designed into the treatment outcome. This requires a paradigm shift in the thought process from being a reactive orthodontist to being a proactive orthodontist.”

Realizing the Full Potential of Clear Aligner Technique

Another area of clear aligner technique where clinicians must revise their knowledge is in their clinical expectations for these appliances.

“Many clinicians and patients think that aligners can only be used for slight corrections versus a complete treatment,” Dr Tai says, “and I would say that this impression may have been correct for the aligners available 15 years ago. However, the technology, material, and software algorithms have evolved significantly since then. Today, clear aligners are the orthodontic appliance of choice for a wide range of occlusions.”

Dr Tai’s personal revelation regarding clear aligner technology’s treatment capabilities came when she treated a touring gospel singer. The catch? The patient lived in New Zealand, and Dr Tai’s practice is in Vancouver, Canada. “Her band toured in North America 4 times a year, and she committed to seeing me every 3 months,” Dr Tai recalls. “Our only option was aligner treatment. The case treated out well with no complications, and it was then that I realized no patient is ‘too far’ and that even challenging cases can be successfully treated with clear aligners. Today, I have patients who fly in to see me from all over the world for clear aligner treatment.

“It is important to understand that clear aligner treatment is a technique, not a product,” Dr Tai continues. “The common misconception is that clear aligners are a ‘compromise’ orthodontic treatment, either prescribed for only minor correction or when a patient’s main concern is esthetics. However, the clear aligner system of today is a comprehensive orthodontic appliance, capable of treating a wide range of malocclusions when in the hands of an experienced clinician.”

The following case—one of many shown in Dr Tai’s book—serves as a striking example of the degree of clinical success that can be achieved with clear aligner technique.

The Danger of DIY Aligner Products

The same benefits of clear aligner treatment that made it possible for Dr Tai to treat a touring gospel singer has also left the field vulnerable to the do-it-yourself (DIY), on-demand economy. A quick internet search will return half a dozen results for online mail-order aligner companies, all with a similar business model: The customer can begin their treatment by requesting an at-home impression kit, which they mail back to the company (some companies also have brick-and-mortar locations solely for impression-taking). The patient’s impression is then converted to a 3D image, and a treatment plan is developed using the aligner software. The company then produces and mails a set of aligners to the patient. The two benefits most commonly advertised for these companies are the time and money they save prospective patients; in fact, many boast that the patient never has to step foot inside a dental office. This naturally raises concern from trained clinicians.

“I think patients need to understand that DIY orthodontic companies are not just offering cosmetic services to make you look more beautiful,” Dr Tai says. “It is not the appliance that treats the patient. It is the orthodontist’s clinical expertise in making a proper diagnosis, treatment planning, and executing the treatment clinically that treats the patient. Moving teeth and changing the bite should only be done within the context of proper diagnosis and an understanding of the occlusion. To move teeth without first ascertaining overall oral health, caries risk, periodontal status, and taking radiographs would amount to malpractice in the place where I practice.”

Many general dentists are also now providing treatment with clear aligners, and while their level of expertise and practice model can in no way be compared to mail-order aligner companies, they still need to understand their limitations. “General practitioners may receive some orthodontic training in dental school or attend continuing education courses to recognize, diagnose, and treat simple malocclusions,” Dr Tai explains. “However, just as a family physician may treat high blood pressure but refer a patient who develops coronary artery disease to a cardiologist, general practitioners must be able to recognize and refer complex malocclusions, particularly in patients with underlying skeletal problems, to an orthodontist for treatment.”

An International Perspective

Part of what makes Dr Tai’s perspective unique is her international experience as a student, as an educator, and as a clinician. Born in Aldershot, England, she studied dentistry at the University of Malaya in Kuala Lumpur, Malaysia, and obtained her certificate in orthodontics at the University of Minnesota in Minneapolis. Since opening her practice in Vancouver, British Columbia, she has continued to lecture internationally, which has resulted in a clinical textbook applicable to dental practices across the globe.

“Through my education, travel, and clinical experience, I have learned that there are different orthodontic philosophies all over the world,” Dr Tai explains. “Malocclusions vary by ethnicity, and some populations have more complex malocclusions. For example, a high proportion of Asian malocclusions in China and Japan are treated with premolar extractions. In clear aligner treatment, the software programs that determine the tooth movements are customizable to accommodate these different approaches to orthodontic treatment. In our example of premolar extraction, these cases are often programmed for maximum anchorage. Extraction sites may also be closed in a variety of ways, such as with moderate anchorage considerations. In Japan, orthodontists use a technique called the staggered staging technique, where the canine is moved for 10 stages then stops, then the incisors are retracted for 10 stages then stop, then the canine is moved another 10 stages, and the sequence is repeated until the extraction spaces are closed.”

Just as it would be hard to prescribe one orthodontic treatment philosophy to every distinct population group in the world, it can be hard to write a clinical orthodontic textbook applicable to many different markets. Through the combination of her professional experience and the fact that clear aligners are available internationally with customizable treatment software designed to individualize treatment based on the patient, Dr Tai’s book accomplishes just that.

“I started lecturing globally in 2011,” she says. “As a result of my travels and interacting with professional colleagues all over the world, I have become more broad-minded and accepting of various orthodontic approaches to treatment. Everywhere I went, dentists and orthodontists expressed interest in learning more about clear aligners and wanted to know what textbook I could recommend. There were no good resources available, so I decided to write my own! It took 6 years to develop the teaching material that forms the foundation and contents of the textbook, which incorporates everything I’ve learned through my practice and my professional travels.”

The Future of Orthodontics

Clear aligner technology has gained significant momentum in recent years, and Dr Tai says this technology shows no signs of slowing down.

“I see clear aligner technology as the future of orthodontics,” she explains. “Just as we now look back on the full-banded appliances of Edward Angle’s day and realize how far orthodontics has evolved and developed since then, one day we will look back at bracket and wire systems in the same way. Clear aligners are part of the larger picture of the digital age and how this era has affected every part of our lives from computers to mobile phones to advances in medicine and dentistry. Dentistry itself now has CBCT for diagnosis and treatment planning, CAD/CAM–milled crowns, 3D-printed models, and digital impressions—a digitally produced orthodontic appliance such as clear aligners is part of this revolution in the technological age. The power of digital treatment planning and the ability to design occlusions with customized tip, torque, and arch forms enables us to serve our patients better and deliver superior treatment outcomes. As clear aligner technique continues to evolve, there is no doubt that one day soon we will be able to treat all malocclusions with clear aligners, and bracket and wire systems will become part of our history.”

As to where her book Clear Aligner Technique fits into this timeline, Dr Tai sees it as an integral piece in bridging the foundation of orthodontic knowledge developed and refined previously with these new advances in digital technology and clear aligner technique.

“I think this book will revolutionize the way dentists and orthodontists think about the future of orthodontics and clear aligners,” she explains. “It establishes clear aligners as a valid orthodontic technique that is capable of treating a wide range of malocclusions. Over and above that, it also demonstrates how clear aligners—when in the hands of a well-trained clinician—are capable of delivering finished results to the same standard of excellence as traditional bracket and wire systems. As both a clinician and educator in this field, my hope is that dental schools will start incorporating clear aligner technique into their curriculum for training orthodontists and dentists. This textbook will be a great resource for educators everywhere. As we move forward, it is also imperative that we take the field of clear aligners seriously and devote the time to do the scientific research that is necessary so that we continue to practice clinically sound, evidence-based orthodontics.”

Dr Tai closes with a quote from her book: “‘The future lies in continuing to innovate with passion to transform the future of our profession.’ At the heart of it all, we are changing smiles and changing lives.”

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Sandra Tai, BDS, MS, has been an Invisalign certified orthodontist since 2000 and is currently an Invisalign Top 1%/Diamond Provider who has treated over 1,500 cases with Invisalign. As an editorial board member for the Journal of Aligner Orthodontics and a member of Align Tech Faculty in North America, she is involved in several clinical research projects and FDA clinical research trials with clear aligners. Dr Tai is currently a clinical assistant professor in Orthodontics as well as the coordinator for the Invisalign program at the University of British Columbia in Vancouver. She also maintains a busy international lecture schedule, speaking to orthodontists all over the world about clear aligners and their potential. Dr Tai is a Fellow of the College of Dental Surgeons of British Columbia and a Fellow of the Royal College of Dentists, Canada, as well as a member of several professional organizations. She is also the founding member and past president of the Orthodontic Ties Seminars Study Club in Vancouver and the Vancouver Invisalign Study Club, where she mentors and trains dentists in the Invisalign system. She received her graduate training in Orthodontics at the University of Minnesota.

 

Clear Aligner Technique

Sandra Tai

Clear aligners are the future of orthodontics, but digital orthodontics evolves so rapidly that it is hard to keep pace. This book approaches clear aligner treatment from a diagnosis and treatment-planning perspective, discussing time-tested orthodontic principles like biomechanics and anchorage and demonstrating how to apply them to orthodontic cases using these appliances. Each chapter explains how to use clear aligners to treat a given malocclusion and teaches clinicians how to program a suitable treatment plan using available software, how to design the digital tooth movements to match the treatment goals, and finally how execute the treatment clinically and finish the case well. This clinical handbook will prepare orthodontists and dental students to exceed patient expectations with the most esthetic orthodontic appliance currently available.

320 pp; 1,344 illus; ©2018; ISBN 978-0-86715-777-2 (B7772); US $218