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American Journal of Orthodontics and Dentofacial Orthopedics
THE USE OF PROPEL TO INCREASE
THE RATE OF ALIGNER PROGRESSION
Dr. Thomas S. Shipley discusses increasing the bone remodeling rate
for more rapid aligner progression
The use of clear aligners has gained broad accep-
tance as an alternative way to orthodontically move
the dentition. As the orthodontic community becomes
more familiar with this modality of treatment, questions
arise as to best clinical practices to achieve optimal re-
sults. One area of interest is how often to change align-
ers. The Invisalign® System suggests the optimal time
to change from one aligner to the next, with good patient
compliance, is 2 weeks. The aligner system and the
amount of movement prescribed in each aligner determine
how frequently the patient is required to change aligners in
the sequence. Changing aligners at a faster rate than the
velocity of tooth movement would be one cause of align-
ers not “tracking” over time. This rate of aligner change is
a limiting factor in the overall case completion time.
In more difficult cases, the number of aligners pre-
scribed may reach as many as 40 to 60 aligners, with
even more in the most difficult cases. To the patient,
who can quickly do the math, and to the clinician, who
knows “refinement” or “auxiliary treatment” has not even
been accounted for yet, the future of the orthodontic
treatment becomes daunting. In these cases, or with
any case, where increased velocity of tooth movement
is desired, a way to change aligners at a more rapid
pace becomes attractive.
The rate of tooth movement is dependent on the rate
of the physiologic process of bone remodeling.1,2
If this
rate of bone remodeling is increased, then the rate at
which aligners should be changed increases also. Failing
to change the aligners fast enough to coincide with the
velocity of tooth movement would be equivalent to plac-
ing intermittent orthodontic forces on the dentition, which
could actually slow the overall progress of the movement.
Increasing the rate of bone remodeling is the key
to being able to change aligners at a more rapid pace,
therefore, decreasing overall treatment time.
A female patient presented at age 21 with a mild
Class II, Division 2 malocclusion. Moderate upper and
lower dental crowding existed with a 60% deep bite
and negatively inclined upper incisors. The patient’s
chief concern was the rotation of the upper left lateral
incisor. The CBCT showed good root parallelism and
normal development of the dentition (Figures 1-7).
Figure 1
Figure 2
Figure 4
Figure 3
Figure 5
INCREASING THE RATE OF
ALIGNER PROGRESSION

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American Journal of Orthodontics and Dentofacial Orthopedics
The treatment plan was developed to use clear
aligners in conjunction with Class II elastics to resolve
the dental crowding, slightly procline the upper and
lower incisors, correct the deep bite, and improve the
Class II dental relationship.
Once the treatment plan was finalized, the resul-
tant prescription for aligners was 43 upper and lower
aligners. The aligners consisted of 43 active maxillary
aligners, and 23 active lower aligners, followed by 20
lower passive aligners (Figures 8-9). Cuts were made
in the upper aligners near the maxillary canines to cre-
ate hooks for Class II elastics and cutouts in the lower
aligners in the buccogingival area of the lower second
molars to allow for Class II button hooks to be bonded
(Figure 14). No interproximal reduction was prescribed.
The patient desired to finish treatment faster
than 86 weeks! The clinician was concerned that this
treatment did not allow much time for refinements
and detailing which may be needed. Both agreed
that Propel would be an appropriate way to speed
the orthodontic treatment.
Propel is a technique performed with the patented
FDA Registered Class 1 510(k)-exempt disposable
medical device that cre-
ates Micro-Osteoperfo-
rations (MOPs). These
MOPs stimulate a cyto-
kine response in the pa-
tient’s alveolar bone dur-
ing orthodontic treatment
(Figures 10- 11).3 MOPs
reduce overall orthodon-
tic treatment time by har-
nessing the body’s own
biology to increase the
rate of tooth movement
and release challenging
movements.4
This in-
office technique can be
performed chairside in
minutes during a patient’s regularly scheduled office
visit and can be used in conjunction with any type of
fixed or removable orthodontic appliance. Micro-Os-
teoperforations with Propel can be used to advance
Figure 6
Figure 8
Figure 7
Figure 9
Figure 10
Figure 11

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American Journal of Orthodontics and Dentofacial Orthopedics
the treatment of any maloc-
clusions, including, but not
limited to, crowding, space
closures, molar uprighting,
rotations, intrusions, and
extrusions.
Aligners 1 and 2 were
delivered at the initial ap-
pointment. The patient was
told to wear each aligner
for 2 weeks and return in 4
weeks for placement of at-
tachments. At the 4-week
return appointment, aligner
3 was delivered, attach-
ments were placed, and
Class II elastics com-
menced. No Propel was used for the first 6 weeks of
treatment. A regular tray progression of 2 weeks per
tray was used. There are several advantages to start-
ing at this pace. The patient has ample time to adapt
to wearing the trays and to learn how to be compliant.
Treatment progressed at a slower pace, not to
overburden the patient with learning to wear the trays,
having attachments placed, beginning elastic wear,
and Propel all at the same time. In addition, the clini-
cian is given an opportunity to gauge patient compli-
ance before beginning Propel. The enhanced cytokine
response with the MOPs would be of little benefit with-
out good patient compliance.
Six weeks into treatment, Propel was initiated. The
use of local infiltration anesthesia (2% Lidocaine with
1:100,000 epinephrine) was employed. “Profound”
topical anesthesia may instead be used. The patient
rinsed twice with chlorhexidine gluconate and expec-
torated. MOPs were placed inter-radicularly using the
Propel device as follows:
Three MOPs mesial and distal of the maxillary lat-
eral incisors, and two MOPs mesial and distal of the
lower incisors (Figures 12-13). She stated that there
was little discomfort of the procedure other than mild
pressure between the teeth in a few areas. A post-Pro-
pel CBCT was taken, which shows the location of the
maxillary left MOPs (see image). The patient rinsed
again with chlorhexidine gluconate after the procedure
and was asked to wear the aligners at a progression of
3 days each.
With such a rapid pace of aligner progression,
close monitoring by the clinician is needed to ensure
patient compliance and good aligner “tracking.” If the
rate of aligner progression exceeds actual tooth move-
ment, it will be apparent due to poor aligner fit. Aligner
progression may be slowed, if needed, based on how
the patient presents on follow-up visits.
The patient was seen 2 weeks later and was
now beginning aligner 9. As shown in the photos,
the aligners were fitting the dentition perfectly (good
“tracking”). This indicated that the progression at
3 days per aligner was appropriate for this patient
(Figures 16-18). In addition, the soft tissue had com-
pletely healed with no signs of trauma at 2 weeks
(Figures 19-20).
Figure 12
Figure 14
Figure 13
Figure 15

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American Journal of Orthodontics and Dentofacial Orthopedics
The patient was seen again 2 weeks later (4
weeks post-Propel). At this time, she was just begin-
ning tray 14, and a CBCT was taken that shows the
MOPs slightly smaller, but still present (Figure 21).
Again, the “tracking” of the aligners was still excellent.
A 4-week interval was now chosen, continuing at 3
days per aligner.
Four weeks later, the patient was wearing the
23rd aligners. The aligners were still “tracking” per-
fectly, and treatment was completed on the lower arch.
Complete resolution of the lower dental crowding was
achieved as prescribed using 23 aligners over a period
of 14 weeks. No refinement or detailing was needed
for the lower arch.
More aligners were delivered, and Class II elastics
were continued. The patient returned every 4 weeks
forward until completion of treatment of the maxillary
orthodontic treatment. The aligner progression con-
tinued at 3 days per aligner. The patient continued to
change the lower passive aligners at the same pace.
At 23 weeks, treatment was completed on the up-
per dentition after the use of 43 upper aligners. No
refinement aligners were needed. Attachments were
removed, and retainers with similar Class II elastic
hooks and cutouts were fabricated. The bonded buccal
hooks on the lower 2nd molars were left for 6 months,
for the continued use of class II elastics for 12 hours
per night as part of the retention protocol. Otherwise,
the clear removable retainers were worn according to
the clinician’s normal retention protocol.
Evaluation of the final records shows adequate
inclination of the upper and lower incisors to allow for
Figure 16 Figure 17
Figure 19
Figure 21
Figure 22 Figure 23 Figure 24
Figure 18
Figure 20

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American Journal of Orthodontics and Dentofacial Orthopedics
better anterior guidance, which was achieved by upper
anterior labial crown torque and lower incisor proclina-
tion aided by the use of Class II elastics. In addition,
the overbite was corrected to an appropriate 30%. The
patient’s chief concern of the rotated upper left lateral
incisor was completely corrected to her satisfaction,
along with complete resolution of the remaining upper
and lower dental rotations. The post-treatment CBCT,
taken 6 months post-Propel, shows the MOPs almost
completely healed (Figure 25).
The final results show that Propel is a good ap-
proach to increasing the rate of clear aligner pro-
gression by increasing the rate of bone remodeling.
Treatment time was reduced over 70% in this case as
Figure 25

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American Journal of Orthodontics and Dentofacial Orthopedics
compared to a typical 2 week interval aligner case.
The overall amount of appointments were reduced
from 20+ to 8. More research is needed to gain a bet-
ter understanding of the exact rate of tray progression
that should be used. A clinician new to this treatment
modality should consider starting at a slower progres-
sion than that shown with this case, such as 7 days
per aligner. Close monitoring should be employed, and
adjustments may be made to the rate of progression
based on the clinical results for each patient.
REFERENCES
1. Henneman S, Von den Hoff JW, Maltha JC.
Mechanobiology of tooth movement. Eur J
Orthod. 2008;30(3):299-306.
2. Krishnan V, Davidovitch Z. On a path
to unfolding the biological mechanisms of
orthodontic tooth movement. J Dent Res.
2009;88(7):597-608.
3. Teixeira CC1, Khoo E, Tran J, Chartres I, Liu
Y, Thant LM, Khabensky I, Gart LP, Cisneros G,
Alikhani M. Cytokine expression and accelerated
tooth movement. J Dent Res. 2010;89(10):1135-
1141.
4. Khoo E, Tran J, Raptis M, Teixeira CC, Alikhani
M, Abey M. Accelerated Orthodontic Treatment
[research paper]. New York: New York University;
2011.
Treatment Progression

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American Journal of Orthodontics and Dentofacial Orthopedics
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Catapult Group, LLC is an ADA CERP Recognized Provider. ADA CERP is a service of the American D
Association to assist dental professionals in identifying quality providers of continuing dental education.
does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit ho
of dentistry. Concerns or complaints about a CE provider may be directed to the provider or to ADA CE
www.ada.org/cerp.
Catapult Group, LLC is an Academy of General Dentistry Approved PACE Program Provider FAGD/MA
Approval does not imply acceptance by a state or provincial board of dentistry or AGD endorsement.
6/1/13 to 5/31/16 Provider #306446
Catapult Group, LLC is an Academy of General Dentisry Approved PACE Program
Provider FAGD/MAGD Credit. Approval does not imply acceptance by a state or
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ABOUT THE AUTHOR
Thomas Shipley, DMD, MS, received his Bachelor of Science degree in Business Management from Brigham
Young University and went on to earn his doctorate from the University of Kentucky College of Dentistry. Dr.
Shipley completed a master’s program in orthodontics at West Virginia University. He maintains a full-time
private practice in Peoria, Arizona, and is an Adjunct Professor at Arizona School of Dentistry, Department of
Orthodontics in Mesa, Arizona. Dr. Shipley maintains membership in numerous professional organizations, such
as the American Dental Association, the Arizona Dental Association, the American Association of Orthodontics,
the Pacific Coast Society, the Comprehensive Care Continuum Study Club; and he is the coordinator of the
International Dental Ed Continuing Education Study Group for the Northwest Phoenix area. He is board certified
by the American Board of Orthodontics.
Catapult Group, LLC is an ADA CERP Recognized Provider. ADA CERP is a service
of the American Dental Association to assist dental professionals in identifying quality
providers of continuing dental education. ADA CERP does not approve or endorse
individual courses or instructors, nor does it imply acceptance of credit hours by
boards of dentistry. Concerns or complaints about a CE provider may be directed to the
provider or to ADA CERP at www.ada.org/cerp.
R
Intended Audience: Orthodontists, Dentists and all Dental Professionals
AGD Subject Code 370