Download the use of propel to increase the rate of aligner progression

THE USE OF PROPEL TO INCREASE
INCREASING THE RATE OF ALIGNER PROGRESSION
THE RATE OF ALIGNER PROGRESSION
T
Dr. Thomas S. Shipley discusses increasing the bone remodeling rate
for more rapid aligner progression
he use of clear aligners has gained broad accep-
ing intermittent orthodontic forces on the dentition, which
tance as an alternative way to orthodontically move
could actually slow the overall progress of the movement.
the dentition. As the orthodontic community becomes
Increasing the rate of bone remodeling is the key
more familiar with this modality of treatment, questions
to being able to change aligners at a more rapid pace,
arise as to best clinical practices to achieve optimal re-
therefore, decreasing overall treatment time.
sults. One area of interest is how often to change align-
A female patient presented at age 21 with a mild
ers. The Invisalign® System suggests the optimal time
Class II, Division 2 malocclusion. Moderate upper and
to change from one aligner to the next, with good patient
lower dental crowding existed with a 60% deep bite
compliance, is 2 weeks. The aligner system and the
and negatively inclined upper incisors. The patient’s
amount of movement prescribed in each aligner determine
chief concern was the rotation of the upper left lateral
how frequently the patient is required to change aligners in
incisor. The CBCT showed good root parallelism and
the sequence. Changing aligners at a faster rate than the
normal development of the dentition (Figures 1-7).
velocity of tooth movement would be one cause of aligners 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 prescribed 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
Figure 1
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.
Figure 2
Figure 3
Figure 4
Figure 5
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 plac1
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medical device that creates Micro-Osteoperforations (MOPs). These
MOPs stimulate a cytokine response in the patient’s alveolar bone during orthodontic treatment
Figure 6
(Figures 10- 11).3 MOPs
Figure 7
reduce overall orthodontic treatment time by harnessing the body’s own
biology to increase the
rate of tooth movement
and release challenging
movements. 4 This in-
Figure 8
office technique can be
Figure 9
performed chairside in
The treatment plan was developed to use clear
minutes during a patient’s regularly scheduled office
aligners in conjunction with Class II elastics to resolve
visit and can be used in conjunction with any type of
the dental crowding, slightly procline the upper and
fixed or removable orthodontic appliance. Micro-Os-
lower incisors, correct the deep bite, and improve the
teoperforations with Propel can be used to advance
Class II dental relationship.
Once the treatment plan was finalized, the resultant 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 create 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 10
(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
Figure 11
FDA Registered Class 1 510(k)-exempt disposable
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the treatment of any malocclusions, including, but not
limited to, crowding, space
closures, molar uprighting,
rotations, intrusions, and
extrusions.
Aligners 1 and 2 were
delivered at the initial appointment. The patient was
Figure 12
Figure 13
Figure 14
Figure 15
told to wear each aligner
for 2 weeks and return in 4
weeks for placement of attachments. At the 4-week
return appointment, aligner
3 was delivered, attachments 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
was little discomfort of the procedure other than mild
tray was used. There are several advantages to start-
pressure between the teeth in a few areas. A post-Pro-
ing at this pace. The patient has ample time to adapt
pel CBCT was taken, which shows the location of the
to wearing the trays and to learn how to be compliant.
maxillary left MOPs (see image). The patient rinsed
Treatment progressed at a slower pace, not to
again with chlorhexidine gluconate after the procedure
overburden the patient with learning to wear the trays,
and was asked to wear the aligners at a progression of
having attachments placed, beginning elastic wear,
3 days each.
and Propel all at the same time. In addition, the clini-
With such a rapid pace of aligner progression,
cian is given an opportunity to gauge patient compli-
close monitoring by the clinician is needed to ensure
ance before beginning Propel. The enhanced cytokine
patient compliance and good aligner “tracking.” If the
response with the MOPs would be of little benefit with-
rate of aligner progression exceeds actual tooth move-
out good patient compliance.
ment, it will be apparent due to poor aligner fit. Aligner
progression may be slowed, if needed, based on how
Six weeks into treatment, Propel was initiated. The
the patient presents on follow-up visits.
use of local infiltration anesthesia (2% Lidocaine with
The patient was seen 2 weeks later and was
1:100,000 epinephrine) was employed. “Profound”
topical anesthesia may instead be used. The patient
now beginning aligner 9. As shown in the photos,
rinsed twice with chlorhexidine gluconate and expec-
the aligners were fitting the dentition perfectly (good
torated. MOPs were placed inter-radicularly using the
“tracking”). This indicated that the progression at
Propel device as follows:
3 days per aligner was appropriate for this patient
(Figures 16-18). In addition, the soft tissue had com-
Three MOPs mesial and distal of the maxillary lateral incisors, and two MOPs mesial and distal of the
pletely healed with no signs of trauma at 2 weeks
lower incisors (Figures 12-13). She stated that there
(Figures 19-20).
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Figure 16
Figure 17
Figure 18
Figure 19
Figure 20
The patient was seen again 2 weeks later (4
of 14 weeks. No refinement or detailing was needed
weeks post-Propel). At this time, she was just begin-
for the lower arch.
ning tray 14, and a CBCT was taken that shows the
More aligners were delivered, and Class II elastics
MOPs slightly smaller, but still present (Figure 21).
were continued. The patient returned every 4 weeks
Again, the “tracking” of the aligners was still excellent.
forward until completion of treatment of the maxillary
A 4-week interval was now chosen, continuing at 3
orthodontic treatment. The aligner progression con-
days per aligner.
tinued at 3 days per aligner. The patient continued to
Four weeks later, the patient was wearing the
change the lower passive aligners at the same pace.
23rd aligners. The aligners were still “tracking” per-
At 23 weeks, treatment was completed on the up-
fectly, and treatment was completed on the lower arch.
per dentition after the use of 43 upper aligners. No
Complete resolution of the lower dental crowding was
refinement aligners were needed. Attachments were
achieved as prescribed using 23 aligners over a period
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 21
Figure 22
Figure 23
Figure 24
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better anterior guidance, which was achieved by upper
and lower dental rotations. The post-treatment CBCT,
anterior labial crown torque and lower incisor proclina-
taken 6 months post-Propel, shows the MOPs almost
tion aided by the use of Class II elastics. In addition,
completely healed (Figure 25).
the overbite was corrected to an appropriate 30%. The
The final results show that Propel is a good ap-
patient’s chief concern of the rotated upper left lateral
proach to increasing the rate of clear aligner pro-
incisor was completely corrected to her satisfaction,
gression by increasing the rate of bone remodeling.
along with complete resolution of the remaining upper
Treatment time was reduced over 70% in this case as
Figure 25
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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 better 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 progression 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
Treatment Progression
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):11351141.
4. Khoo E, Tran J, Raptis M, Teixeira CC, Alikhani
M, Abey M. Accelerated Orthodontic Treatment
[research paper]. New York: New York University;
2011.
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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
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Original Release Date: March 2014
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Please visit www.catapultuniversity.com to take the CE quiz and obtain your certificate of completion.
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Intended Audience: Orthodontists, Dentists and all Dental Professionals
Subject Code 370
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