September 2019
Volume 40, Issue 8

What Impact Is Clear Aligner Therapy Having on Orthodontic Treatment?

Robert L. Boyd, DDS, MEd; Sandra Tai, BDS, MS; Donna Galante, DMD

Dr. Boyd

The most rapidly developing and exciting new area for clear aligner therapy is early mixed dentition treatment-traditionally called phase 1 treatment-in growing children (ages 6 through 10). Since crowding is commonly encountered at an early age, phase 1 treatment with clear aligners typically involves expansion until normal arch width is attained. This usually means widening the arches to established norms and achieving some anterior movement of incisors, especially in deep overbites, until class I molars, normal overbite, and 1.5 mm spacing is present mesial and distal to the primary canines. This type of treatment planning enables straightforward software-generated computer plans that are similar for most class I patients.1

Conventional early treatments typically depend on all four upper incisors being erupted for fixed treatment, so treatment is usually delayed until the middle or late mixed dentition at age 8 to 10 years. Parents often appreciate having their child's teeth straightened with clear aligner therapy at an earlier age than with traditional methods.

Class II patients who are at risk for incisor damage (especially youths involved in sports) can be started with treatment as early as 7 years old when only upper central incisors are erupting, because the lateral incisors can be accommodated with space and a temporary pontic, which guides the permanent teeth into a normal path of eruption. Class II patients may also receive clear aligner treatment with a new mandibular advancement (MA) feature, which works like a twin block appliance or other removable functional appliance. With the MA feature, class II correction can occur faster than with other appliances because the aligner is worn almost full time, like a Herbst appliance, rather than only at nighttime. Thus, clear aligner with MA therapy for mixed dentition class II correction can result in faster treatment, often accomplished in less than 12 months.1

Additionally, when comparing phase 1 clear aligner therapy (and subsequently clear aligner therapy for teenagers if a second phase is needed in the permanent dentition) to treatment that utilizes sharp wires and other types of appliances that may poke the soft tissue, the smooth thermoplastic aligner enhances patient comfort, and the need for emergency visits for repair is typically lessened.

Conventional phase 1 treatment in the mixed dentition has been shown to usually lead to shorter treatment time in the second phase of treatment (that is, the teenage permanent dentition, if necessary), with less need for later permanent teeth extractions.2 Logically, these outcomes could also be expected for phase 1 clear aligner treatment.

The teenager market is a rapidly expanding area in clear aligner treatment. This second phase of therapy in the permanent dentition for teenagers can offer the same benefits as those attained during phase 1, including longer intervals between visits, shorter visits, reduced treatment time, and better esthetics and improved hygiene during treatment. Clear aligner therapy has also been found to be effective in open-bite treatment, which is a notoriously difficult treatment for fixed appliances.3

Finally, the management of sleep apnea and other airway issues in conjunction with orthodontic treatment is another emerging area. This type of orthodontic treatment emphasizes initial CBCT airway evaluation and, when a problem is detected, preference for non-extraction treatment via arch expansion and correction of class II malocclusions by moving teeth forward to open the airway. This is a complex area of dentistry beyond the scope of this article, and requires a discussion of early management of airway issues during orthodontic treatment. At present, clinicians are using other mandible-protruding appliances for treatment to open the airway as the clear aligner MA appliance potentially could. The MA appliance positions the mandible in a more forward position like sleep apnea appliances do. Some clinicians are currently gaining experience with MA appliances for this specific application of expansion and movement of the mandible forward for airway issues because of the potential positive effect of increasing the dimensions of the airway.

Dr. Tai

Clear aligners represent a revolutionary change in orthodontic appliances for the 21st century, offering many benefits over traditional fixed appliances. From a patient's perspective, a clear aligner is esthetic, easier to clean, and more comfortable and has no dietary restrictions. From a clinician's viewpoint, teeth can be moved in different ways, such as sequential distalization, with better control of intercanine width, anchorage, and lower incisor position. Clear aligner therapy also offers the benefit of digital treatment planning where the treatment outcome and the process required to achieve it may be visualized on a software program.

Clear aligner technique started as an adult orthodontic treatment alternative. However, with innovations that allow the clinician to address more comprehensive malocclusions, such as correction of class II and class III discrepancies, deep bites, open bites, and even extraction cases, clear aligners are increasingly becoming the orthodontic appliance of choice for teenagers. Because of their involvement in extracurricular activities like sports and music, many teenagers find clear aligners a convenient alternative.

Recent innovations such as clear aligners for phase 1 therapy offer treatment for mixed dentition interceptive therapy. Studies at the University of the Pacific have shown that a phase 1 treatment leads to shorter phase 2 treatment times with fewer extractions. The younger the age of the patient, the more concerns parents typically have regarding their child undergoing orthodontic treatment. Clear aligners address many parental concerns regarding pain, diet, oral hygiene, and emergency appointments.

The guidelines for a general practitioner to refer to an orthodontist for orthodontic treatment should be based on degree of difficulty of the malocclusion, not specifically on the type of orthodontic appliance the patient requests. Simple class I malocclusions that do not require extractions and do not have severe discrepancies in the vertical plane, such as deep bite or open bite, should be within the scope of the general practitioner. Another guideline could be that simple treatments that can be completed in less than 1 year should be within the scope of general practice. However, more complex cases like a skeletal malocclusion with severe anterior-posterior discrepancy, extraction cases, and severe vertical discrepancies should be referred to an orthodontist.

As for do-it-yourself (DIY) and mail-order aligner treatments, the public needs to understand that aligning teeth is not just a cosmetic procedure. It is not the appliance that treats the patient. It is the orthodontist who makes a proper diagnosis and treatment plan with an understanding of growth and development and the biological processes of teeth movement that not only aligns teeth but addresses skeletal discrepancies and corrects malocclusions.

Dr. Galante

When clear aligner technology was launched in 1999, there was much skepticism in the dental community about the utilization and actual effectiveness of the treatment for moving teeth and correcting orthodontic problems. Today, after 20 years of usage, this therapy and its impact on how clinicians treat patients has disrupted an entire industry.

Initially, the marketing and sales of clear aligners focused on adult patients. Candidates would present with a class I occlusion and have either mild spacing or crowding issues and slight overbite, but typically no serious malocclusion. At the onset it seemed this technology would provide a creative solution for patients who wanted a better smile but did not wish to be seen with metal braces and wires. Adults were excited and sales soared, and eventually the makers of clear aligners targeted a new and much larger market segment, teenagers.

Today, between the software capabilities, the flexible thermoplastic material, and even the artificial intelligence incorporated into the process, clear aligners are rather remarkable, efficient, and effective appliances for treating adults, teenagers, and even mixed dentition cases. Recent design advances include the use of the appliance for children as young as 6 or 7 with phase 1 therapy. This product provides doctors the ability to offer a phase 1 clear aligner treatment for approximately 18 months. With "smart" features that are customizable for the mixed dentition and the use of patented staging to enhance the process of expansion in these cases, clear aligners are now available for doctors wanting to use a removable appliance for their phase 1 patients.

I have had great results with clear aligners in phase 1 patients. Use of this therapy has allowed my practice to eliminate many of the fixed appliances we traditionally used to correct narrow arches, crowding, deep bite, and minor crossbite problems early. Incorporating this treatment has been a practice-builder. It allows us to finish cases slightly ahead of schedule and avoid the pitfalls of brackets, such as emergency visits and poor oral hygiene. Parents appreciate the process as well, as typically fewer visits are needed and the child's eating habits do not have to be monitored so closely.1

Another innovation has been clear aligners with mandibular advancement. In my practice this product is successfully utilized in growing children with class II skeletal malocclusions presenting with mandibular retrognathia. Custom-designed precision wings are placed strategically in the molar and premolar areas of the aligners, and once patients occlude with the aligners in place, they are forced to gently bite forward into a more protrusive position. The protrusive bite jumps occur every 8 weeks and are typically 2 mm. This comfortable, easy-to-wear appliance aligns the teeth and corrects the skeletal malocclusion simultaneously.


The authors are consultants for Align Technology, Inc.

Robert L. Boyd, DDS, MEd

Former Chair, Department of Orthodontics, Arthur A. Dugoni School of Dentistry, University of the Pacific, San Francisco, California; Principal Investigator for the first clinical study of Invisalign® orthodontic appliance

Sandra Tai, BDS, MS

Clinical Assistant Professor, Graduate Orthodontics, Faculty of Dentistry, University of British Columbia, Vancouver, Canada; Private Practice specializing in Orthodontics, Vancouver, Canada; Fellow, College of Dental Surgeons of British Columbia; Fellow, Royal College of Dentists, Canada

Donna Galante, DMD

Faculty, Harvard School of Dental Medicine, Boston, Massachusetts; Clinical Instructor
and Faculty Member, Align Technology, Inc; Private Practice specializing in Orthodontics, Rocklin, California; Diplomate, American
Board of Orthodontics


1. Galante D. Clear aligners in phase 1 treatment. Orthotown. 2018;11(7):46-51.

2. Oh H, Baumrind S, Korn EL, et al. A retrospective study of Class II mixed-dentition treatment. Angle Orthod. 2017;87(1):56-67.

3. Garnett BS, Mahood K, Nguyen M, et al. Cephalometric comparison of adult anterior open bite treatment using clear aligners and fixed appliances. Angle Orthod. 2019;89(1):3-9.

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