Inside Dentistry
October 2020
Volume 16, Issue 10

Recovering a Clear Aligner Case After COVID-19

Using the PDL and bone physiology to achieve tooth movement

Cynthia Lynne Graves, DDS

When the patient's chief concern stopped tracking, and then, a global pandemic interrupted the delivery of the clear aligner orthodontia, it became time to get creative. The following case explores treatment options and periodontal ligament (PDL) management in the provision of interrupted clear aligner therapy.

Case Report

A 48-year-old woman presented to the practice as a new patient and requested clear aligners to "fix her crooked tooth" (ie, tooth No. 10) (Figure 1). The preoperative patient consultation is an excellent opportunity to establish goals and build expectations. It's especially important when a doctor-patient relationship is new because trust is more fragile. As part of the patient's history and examination, clinical photographs were taken, which demonstrated wear on the lower incisors (Figure 2). It was explained that realignment could protect her teeth while mitigating gingival clefting. Such discussions are marketing opportunities that can help to create value in orthodontia that goes beyond esthetics.

Impressions were taken, and the clear aligners (Clear Aligners, ClearCorrect) were fabricated and delivered. One of the patient's family members had previously completed orthodontic treatment with ClearCorrect aligners, so she asked for them by name. When compared with other clear aligner systems made available during the past 16 years, the higher trim line of the ClearCorrect aligners results in a longer aligner, which provides excellent retention, facilitates efficient tooth movements with less intrusion of the upper and lower incisors, and requires fewer attachments. In addition, ClearCorrect's aligner material has been associated with fewer fractures and failures, and it can help to achieve fuller engagement of the teeth, which may result in more predictable results and fewer case revisions.

At the patient's fourth aligner check, tooth No. 10 wasn't tracking as planned; therefore, unscheduled interproximal reduction was performed to provide the space required for tooth No. 10 to properly rotate into place. Light hand stripping is sometimes needed when a tooth lacks sufficient space to complete scheduled movements.1 Even when the treatment plan is followed, and the patient is fully compliant, additional interproximal reduction can be required. Each interproximal space must be checked and adjusted using a four-handed technique with the same force applied that the tooth will be under during planned aligner movements. Because the PDL can flex and rebound, it's easy to become confused into thinking that adequate space is present when the adjacent teeth actually lack clearance to pass each other under the force applied by aligners. In this case, Tooth No. 10 lacked the space to rotate.

When performing this interproximal reduction, force must be applied to both of the adjacent teeth in the direction of their planned movement. This can be achieved using fingertip or instrument handle pressure on the teeth, simulating the forces of each aligner. In this case, force was applied to the distal axial wall of tooth No. 9 in a buccal direction, and to the mesial axial wall of tooth No. 10 in a lingual direction. Floss was passed through the contact while these forces were being applied to test it. Next, light interproximal reduction was performed until the floss was able to pass through the contact while forces were being applied without dragging.

At the next aligner check, the initial movement of tooth No. 10 was confirmed, and the decision was made to stay on plan. The patient was instructed to wear her fifth aligner until she was scheduled return in 2 weeks to confirm that tooth No. 10 had been recaptured.

Then the COVID-19 pandemic shut down dental practices. The patient only had the fifth aligner in her possession, so after 2 weeks, she was instructed to only use it at night. The community became a COVID-19 hot spot, and then the shutdown ensued, which significantly delayed her next visit. This 118-day interruption in active movement changed her bone physiology because dynamic force was no longer being applied to the teeth.

When the shutdown ended and the patient could be reappointed, she returned to the practice to resume treatment with micro-osteoperforation. As this would be her first "real procedure" at the practice, nitrous oxide and local anesthetic were used to increase patient comfort. First, the patient was checked for adequate space (Figure 3), and light hand stripping was performed where necessary (Figure 4). Next, micro-osteoperforation (Excellerator® PT, Propel Orthodontics) was performed at 14 sites on the bone adjacent to the teeth in both the upper and lower arches from the distal aspects of the canines and across the midline to the distal aspects of the contralateral canines (Figure 5).

Three aligners were delivered to the patient with 7-day wear cycles prescribed for each. The patient was also given a high-frequency vibration device (VPro+, Propel Orthodontics) to use for 5 minutes each day. The vibration created by the device maximizes tooth movement by engaging aligners and stimulating bone formation.

Three weeks later, the patient returned wearing her eighth aligner. Although tooth No. 10 was not 100% engaged, it was predicted to achieve rotational movements with the remaining aligners. When it did not, additional composite buttons, elastics, and refinement aligners were used.

The patient reported experiencing mild postoperative pain for 2 days at some of the sites where micro-osteoperforation was performed, but she noted rapid movement of tooth No. 10 while wearing her seventh aligner, which motivated her to maintain compliance with the aligner therapy and use her high-frequency vibration device.

At the completion of the orthodontic treatment, the patient expressed that she was thrilled with the results (Figure 6 through Figure 8). To further improve the esthetics of her smile restorativey, tooth No. 10 would undergo cosmetic reshaping and the mandibular incisors would be further refined, as well.


The PDL can be both a friend and enemy, and it can be deceptive. Clinicians should bear in mind how it moves and rebounds while confirming that teeth have the space necessary to complete planned movements. One reason that the PDL is the dentist's friend is because it helps with boney remodeling. As forces are applied to teeth, PDL compression creates an inflammatory response that spreads to the bone. Furthermore, compressive torque forces applied by micro-osteoperforation can create microfractures in bone, inciting localized inflammation to achieve faster bone remodeling.2

The use of a high-frequency vibration device to target the PDL increases cytokine and chemokine levels, facilitating activation of osteoclastic bone changes while also providing increased engagement of the aligners on the teeth. These devices can also help to reduce the pain and discomfort experienced during clear aligner treatment.3

About the Author

Cynthia Lynne
Graves, DDS
Private Practice
Austin, Texas

For more information, contact:


1. Somers JL. Tight Contacts. ClearCorrect Website. https://support.clearcorrect.com/hc/en-us/articles/212179368-Tight-Contacts. Updated July 31, 2018. Accessed August 21, 2020.

2. Alikhani M, Raptis M, Zoldan B, et al. Effect of micro-osteoperforations on the rate of tooth movement. Am J Ortho Dentofacial Orthop. 2013;144(5):639-648.

3. Alansari S, Atique MI, Gomez JP, et al. The effects of brief daily vibration on clear aligner orthodontic treatment. J World Fed Ortho. 2018;7(4):134-140.

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