Treating a complex Class III case with segmented clear
aligners, elastics, high-frequency vibration and virtual visits
by Dr. David R. Boschken
March 1, 2020, was a disruptive day: California issued a
shelter-in-place order that would stay in effect for 3½
months. This resulted in a sharp decline in dental care
use, which persisted for many months.1 During practice closure,
demand for teledentistry options increased 60-fold1 but not all
practices were ready for the absolute digital adoption that would be
required to help them survive the shutdown and following months.
Some authors report that patients treated with fixed appliances
during the COVID-19 pandemic had more problems and emergency
visits than clear aligner patients.2,3 This discrepancy in emergency
visits may have been related to issues with wires or brackets, while
aligners can be disposed of and replaced with the next sequential
or previous aligner as needed.
With the disruption of in-office visits for patients, there was
a need for properly managing patients’ treatment needs while
maintaining proper protocols required by shelter-in-place regulations
and COVID-19. Our offices had already made the transition to
Invisalign’s digital platform, which includes a suite of tools that
help capture data and digital imaging, create treatment plans, direct
the fabrication of clear aligners and retainers, and allow doctors to
monitor and communicate with patients remotely.
For my practice, the most indispensable tool ended up being
Invisalign’s Virtual Care system. Being able to monitor my patients’
progress remotely let the practice ensure continuity of care while
minimizing physical contact. During 2020, we used Virtual Care
with more than 300 cases, which allowed patient treatment to occur
with no in-office visitation after the initial consultation and setup
appointments. One such case is presented here.
Diagnosis and etiology
A 24-year-old patient with a Class III skeletal/dental malocclusion
(Fig. 1) came in concerned about his anterior crossbite. He presented
with a retrognathic maxilla and slight prognathic mandible, mild
upper (2 mm) and lower (1 mm) crowding, anterior crossbite,
10% overbite, mandible deviated to the left (2 mm), lower midline
shifted to the left (2 mm), missing teeth #1, #16, #17 and #32, and
moderate lower anterior facial recession (1–2 mm).
Panoramic radiography (Fig. 2) noted a generalized reduction
of 1–2 mm in lower anterior alveolar bone levels and confirmed
the patient was missing third molars from previous extractions.
The lateral cephalogram (Fig. 3) and Wits analysis (Fig. 4)
confirmed a Class III skeletal pattern (ANB -3.9 degrees and Wits
Appraisal -8.6 mm) because of mandibular prognathism (SNB
83 degrees) and maxillary retrognathism (SNA 79.1 degrees).
After a thorough discussion with the patient regarding our
clinical analysis, we identified the following treatment objectives:
• Create a bilateral Class I dental occlusion
(molar and canine).
• Correct the anterior crossbite to establish ideal
• Correct the mandibular dental midline deviation.
• Correct the maxillary and mandibular deficiency
to address the patient’s main aesthetic concern.
• Most importantly, establish an ideal long-term
Because the patient’s previous consultations with other practitioners
had all resulted in treatment plans that recommended surgery and/
or extraction, we set out to prove that segmental mechanics using
Invisalign clear aligners (Align Technology) was a viable option.
During the in-office exam, we suggested two treatment options
with the patient; for each, the discussion included advantages,
disadvantages and risk analysis.
The first option was directed toward fixing the patient’s skeletal
issues with a combination of orthognathic surgery and clear aligners.
This option had the advantages of predictability and long-term
stability, but the patient immediately declined any surgical correction.
The second option was a nonsurgical treatment plan that involved
segmentalizing clear aligners in a virtual Class III (VC3) setup,
Class III elastics and accelerated orthodontics using high-frequency
After the patient decided on the second option, we completed an
intraoral scan using an iTero device (Align Technology) and ordered
an initial 28 SmartForce/SmartTrack maxillary and mandibular
aligners to be fabricated by Invisalign.
We sectioned lower aligners distal to the lower anterior 2–2
teeth (teeth #23–#26) and added Class III buttons from the lower
canines to the upper first molars (Fig. 5). Upper aligners would
not be segmented.
The lower aligner, upper aligner and elastics were to be worn at
least 20 hours a day. The patient was instructed to wear 3/16-inch,
6-ounce elastics for 20 hours a day for six weeks, then switch to
3/16-inch, 8-ounce elastics until it had been ascertained that Class I
occlusion had established. Weekly virtual monitoring helped ensure
compliance and reduce risk of “overcorrection” of occlusion.
Teeth #23–#26 were to remain stationary, while lower canine
to second molar (bilateral) distalization into a full Class I occlusion
was programmed. Optimized attachments on the upper and lower
canines, bicuspids and first molars were added for aligner retention,
and Class III cutouts for button and elastic placement were used.
The upper anterior was proclined with a 1 degree-per-aligner palatal
root torque, with a maximum of 10 degrees.
The patient was told to use HFV (Propel Orthodontics/Dentsply
Sirona) for five minutes every night while wearing the aligners, and
to switch out aligners every five days if the corrective treatment and
compliance stayed on track.
To confirm case progress, each week the patient used a provided
lip retractor before taking progress photos, which were uploaded
to the Virtual Care platform so the treating doctor could verify
the progress (Fig. 6). Because of the high level of transparency and
communication with this system, the patient and doctor were able to
develop a fun bonding experience that rarely exists with traditional
No adverse movements or fit issues were noted during treatment.
Fig. 7 shows the end-stage views of the lower arch in full Class I
Orthodontic treatment was completed in 10 months—much
quicker than the original estimate of 18 months.
The extraoral clinical exam at the final appointment (Fig. 8)
noted the improvements in the patient’s profile: Proper lower lip
setback was at normal limits, while the interincisal angle improved
from the original 120 degrees to 135 degrees. The intraoral clinical
exam showed ideal dental arch alignment, correction of the patient’s
Class III malocclusion and alignment of his midline.
The posttreatment OPG (Fig. 9) showed proper root
alignment, with no root resorption issues and no further anterior
alveolar bone loss. Posttreatment cephalometric analysis (Fig. 10) showed maintenance of the sagittal relationship: SNA changed
from 79.1 degrees to 79.5 degrees, SNB changed from 83.0 degrees
to 82.6 degrees, and ANB changed from -3.9 degrees to -4.1 degrees.
While the maxillary incisor did not change much (U1–FH
from 122.6 degrees to 121.5 degrees), the mandibular incisor was
improved during treatment and correctly positioned within the mandibular symphysis. (IMPA changed from 104.3 degrees to
86.9 degrees.) The patient’s facial profile (Figs. 11–13) improved by
proper repositioning of the lower lip (lower lip to E-plane 1.5 mm
changed to -2.4 mm). Additionally, the FMIA (L1–FH) improved
from 62.6 degrees to 77.3 degrees.
The patient was satisfied with the clinical results and expressed
gratitude for achieving his beautiful new smile.
Managing Class III malocclusions is often challenging because
of skeletal/dental responses, patient compliance and patient burnout
concerns. This case was successfully treated using a combination
of clear aligners, Class III elastics, accelerated orthodontics using
HFV, and remote monitoring.
The segmentalization of aligners for Class III malocclusions had
not been well researched or published before this case was initiated.
From my perspective, existing third-party “distalizers” require
more office appointments, exhibit frequent breakage and unwanted
reactive movements during treatment, and carry additional overhead
cost. The pandemic pushed the need for an effective alternative.
Also, I have seen with Class III cases that using distal movement
products can result in issues with canine extrusion/rotation and
molar axial tipping/rotation from heavy use of elastics. These issues
are often addressed later and fixed once the sagittal correction is
completed. With VC3 mechanics using clear aligners as a tool,
these unwanted “reactive” movements are minimized. Total control
of first- (expansion), second- (vertical) and third- (torquing) order
movements are effectively managed using Invisalign’s software.4,5
While more research is needed with VC3 cases, what is apparent
is how effective segmentalizing aligners works with channeling
en masse distalization. Teeth move seamlessly through the alveolar
bone without resistance from the anterior teeth. Stationary placement
of the lower anterior teeth helps reduce drag while the posterior
teeth move distally. As with many distal movement cases, removal
of wisdom teeth can be a necessary requirement.
Summary and conclusions
Using a long-established concept of sectioning aligners to
generate predictable and controlled movement, complex Class III
cases that often are planned with surgical correction and/or
extraction of teeth can be successfully treated with clear aligners
alone. This provided a benefit to this patient, who sought to avoid
surgery, which was proposed in preceding consultations.
This case study also provides insight into technologies that
allow for improved patient management and successful treatment
for complex cases without frequent in-office visits.
1. Choi, SE, Simon, L, Basu, S, and Barrow, JR (2021). “Changes in Dental Utilization Patterns
Due to COVID-19 Among Insured Patients in the U.S.” The Journal of the American Dental
2. Bustati, N, and Rajeh, N. (2020). “The Impact of COVID-19 Pandemic on Patients Receiving
Orthodontic Treatment: An Online Questionnaire Cross-Sectional Study.” Journal of the World
Federation of Orthodontists, 9(4), 159–163.
3. Colonna, A, Siciliani, G, and Lombardo, L. (2021). “Orthodontic Emergencies and Perspectives
During and After the COVID-19 Pandemic: The Italian Experience.” Pesquisa Brasileira em
Odontopediatria e Clínica Integrada, 21.
4. Zimmo, N, Saleh, MH, Mandelaris, GA, Chan, HL, and Wang, HL. (2017). “Corticotomy-Accelerated
Orthodontics: A Comprehensive Review and Update.” Compendium of Continuing
Education in Dentistry (Jamesburg, N.J. : 1995), 38(1), 17–26.
5. Cai, Y. (2021). “Effectiveness of Vibration (Cyclic Loading) in Accelerating Bone Remodeling
and Orthodontic Tooth Movement: A Short Review.” Journal of Mechanics in Medicine and
Dr. David R. Boschken graduated with a double major in biochemistry and
anthropology from the University of California, Berkeley, then finished his
dental degree and orthodontic training at the University of Pennsylvania
School of Dental Medicine. Boschken has been treating Invisalign patients in
the San Francisco Bay Area since 2000, with private practices in Los Altos and
San Jose. A member of Align’s global faculty for more than 23 years, he also is
a key opinion leader for Propel Orthodontics and LightForce Orthodontics.