Eastman Institute Studies Present New Data about Clear Aligner Therapy Outcomes

Jul. 3, 2024

For the last five years, Dr. Dimitrios Michelogiannakis, Eastman Institute for Oral Health associate professor, and his team have been working to gather evidence to help advance the knowledge base about outcomes of clear aligner therapy, which has gained increasing popularity in recent years.  

woman with braces smiling and pointing at them

Clear aligner therapy, or CAT, is appealing to adults and children because they are less obvious than braces, they’re more comfortable and are removable while eating and brushing.

However, compared to traditional metal braces, CAT is associated with challenges regarding the effectiveness of controlling orthodontic tooth movement and correcting more complex types of dentoskeletal malocclusions.

There are several clinical studies indicating the limitations of CAT toward expressing the planned digital outcomes.

“On the other hand, there are several commercial entitities, companies, and even providers who have made anectodal claims regarding the potential benefits of CAT on patients’ oral and general health,” said Dr. Michelogiannakis, program director, EIOH Orthodontics and Dentofacial Orthopedics Residency Program.

professional portrait of Dr. MIchelogiannakis
Dr. Dimitrios Michelogiannakis, Eastman Institute for Oral Health associate professor

Such anecdotal claims include the use of non-extraction CAT to perfectly align the teeth while enhancing the periodontal tissue and bone support; the ability of CAT to improve patients’ breathing and sleep quality by expanding the dental arches (thus potentially increasing airway volume); and even the ability to lose weight while undergoing CAT, often referred to as the Invisalign diet.   

“Because there has been a lack of clinical research to actually test these claims,” explained Dr. Michelogiannakis, “we set out to develop well-designed studies to objectively examine the outcomes of CAT.”
The results of these studies can help improve the care of many children and adults being treated with or seeking CAT, while protecting the general public from potentially false or unfounded marketing claims, he added.

To date, Dr. Michelogiannakis and his team have conducted seven clinical studies:

Three clinical studies examined the effectiveness and predictability of CAT in:

1. intruding the anterior teeth in patients with deep bite malocclusion;

2. distalizing (moving backward) the upper teeth in patients with protruded upper teeth; and

3. expanding the dental arches in patients with crowding (to gain space to align the teeth).

Results showed that CAT can produce favorable orthodontic outcomes in relation to the examined orthodontic tooth movements; however, the achieved tooth movements were considerably less than the projected/planned ones as part of the digital plan. This should be taken into consdideration when clinicians plan their cases with CAT as well as when they communicate the plan and goals with their patients as part of the informed consent process. It also indicates the need to “over-plan” or “over-correct” specific orthodontic problems when using CAT.

Two clinical studies examined the presence and magnitude of bone defects around teeth before and after non-extraction CAT in adult patients with crowded dentitions. Results indicated that dental expansion with CAT may increase the presence of bone dehiscences and fenestrations in adults with crowded dentitions. This research was the first in the literature to assess this aspect of CAT and highlights the need of clinicians to be judicious while planning dental expansion in patients with crowding in order to avoid moving teeth outside their natural alveolar housing/bone.


One clinical study evaluated the airway volume in adult patients with crowded dentitions treated with non-extraction CAT (including dental expansion of the arches). Results showed that the airway volume did not increase or improve with CAT. This highlights the importance of restraining from making marketing claims to patients that CAT will necessarily improve their breathing.

One clinical study examined weight changes in patients treated with braces and CAT; which tested the Invisalign Diet hypothesis. Results revealed that CAT cannot be used as a predictable weight loss strategy in adults in the general population.

These studies have already led to three publications in peer reviewed journals, with others in the process:

Santucci, V.; Rossouw, P.E.; Michelogiannakis, D.; El-Baily, T.; Feng, C. Assessment of Posterior Dentoalveolar Expansion with Invisalign in Adult Patients. Int. J. Environ. Res. Public Health 2023, 20, 4318.

Allahham DO, Kotsailidi EA, Barmak AB, Rossouw PE, El-Bialy T, Michelogiannakis D. Association between nonextraction clear aligner therapy and alveolar bone dehiscences and fenestrations in adults with mild-to-moderate crowding. Am J Orthod Dentofacial Orthop. 2023 Jan

Horani S, El-Bialy T, Barmak AB, Rossouw PE, Michelogiannakis D. Changes in Airway Dimensions Following Non-extraction Clear Aligner Therapy in Adult Patients with Mild-to-moderate Crowding. J Contemp Dent Pract 2021

“Our findings from these clinical research studies provide useful insight regarding the capabilities as well as limitations of CAT,” said Dr. Michelogiannakis. “Understanding treatment limitations can help develop appropriate treatment adaptations to enhance patient care.”

He also stressed that clear aligner therapy needs expert planning and monitoring in respect to patients’ individual biological and medical characteristics and many times interdisciplinary treatment approaches including various dental and medical doctors and specialists.

“Clear aligner therapy is constantly developing and improving with the development of new materials and techniques such as the use of newer 3D printed aligners,” he added. “It is pertinent to continue conducting clinical research to test the actual clinical impact and performance of new orthodontic technologies and products. Treatment strategies and marketing claims should be based on evidence-based and unbiased data to better serve our patients’ medical oral health needs.”