Invisalign Therapy: A Guide to Clear Aligner Treatment

Contents
× Introduction
× History of overlay appliance
× Essix appliance
× Principles and Biomechanics
× Invisalign
× History of Align technology
× Steps of Invisalign process
× Taking impressions - Best practices
× Align’s standard on quality
impression
× Virtual diagnostic setup
× Scanning of impressions
× Invisalign software
× ClinCheck
× Stereolithography
× Staging
× Attachments
× Tooth movement with Invisalign
× Surgical treatment and Invisalign
× Conclusion
× References
3

Introduction
With increasing
sophistication “Clear
Aligner Technology” offers
a invisible method of
straightening the teeth.
Everybody wants to look
great, at work, at school,
and with friends and in the
society.
4

× The present era has
evolved to emerge
with a new treatment
modality other than
the regular arch wires
and brackets.
× A recent technological
advance in
orthodontics is the
Aligner system, which
combines the idea of
using overlay
appliances and the
application of three-
dimensional
technology to move
teeth.
5

Movement of teeth without the use of bands,
brackets, or wires was described by Dr H. D.
Kesling as early as 1945.
By using a flexible tooth positioning appliance
called Vulcanite tooth-positioning appliance as a
method of refining the final stage of orthodontic
finishing after debanding.
7Orhan.C.Tuncay. The Invisalign system. First edition 2006.

8
•As early as 1926, however, Remensnyder had
introduced the Flex-0-Tite gum-massaging appliance,
with which he reported achieving minor tooth
movements.
•Later Nahoum (vacuum formed dental
contour appliance ,1964)
•In 1971, Ponitz introduced a similar appliance called
the “invisible retainer” made on a master model that
prepositioned teeth with base-plate wax.
Orhan.C.Tuncay. The Invisalign system. First edition
2006.

9
The Two contemporary systems for
moving teeth with plastic appliances are
the Essix systems and Clear Aligner System
× The Essix System is based on in-course
adjustments of what is essentially a
single appliance to achieve the
treatment goals.
× The Clear Aligner System is unique in
that ,the clinician must be able to plan
the path to optimal results before
treatment is initiated so that a series
of aligners can be constructed to
achieve treatment objectives.
Orhan.C.Tuncay. The Invisalign system. First edition 2006.

10
• ESSIX RETAINER
Clear Aligner
System

× First introduced in 1993 by Raintree essix
× It’s a plastic removable device that snaps over
the teeth and is invisible.
× Its inexpensive and can be quickly fabricated,
× Minimal bulk with sufficient strength,
× Retentive without clasps,
× Usually requires no adjustment
× ‘Does not interfere with speech, efficiency of the
occlusion, and function.
11
2006.

14
Force +
Space +
Time
=
Tooth
movement
2006.

Creating space:-
There are two types of space that must be
evident for tooth movement with Essix
appliances
1) Space within the appliance.
2) Space within the dentition.
15

A. Blocking out the cast
B. Cutting a window
16
2006.

A. Extraction: Extraction is not a suitable option for gaining space
with plastic appliances because it is difficult to upright roots
and to efficiently close any remaining extraction space after
the crowding is resolved.
B. Expansion: Expansion with a clear plastic appliance is possible,
but arch coordination is difficult during the finishing stage
C. Interproximal reduction:
× To avoid the complexities associated with extraction or
expansion, the judicious removal of interproximal enamel is
indicated.
Various techniques:-
a) Metal strip
b) Hand piece-mounted reducing disks.
c) Air-rotor stripping (ARS).
17Orhan.C.Tuncay. The Invisalign system. First edition
2006.

There are two methods
1. Hilliard thermopliers alters the appliance by spot-
thermoforming it to induce force when appliance is
seated.- Bubble bump
2. Mounding does not alter the appliance to induce
force. It involves the sequential placement of small
mounds (layers) of bonding composite on the surface
of the tooth.
× These two basic systems can be used independently or
in combination.
2006.

19
× The location of force determine
the type of tooth movement.
× If the force is placed incisally,
more tipping will be evident on
the target tooth.
× If the force is placed gingivally,
more bodily movement will occur
as force is applied more towards
the center of resistance.
2006.

20
Torque
× Essix-induced root positioning is more
efficient than edgewise bracket because
the moment arm of the couple
generated is longer than the edgewise
bracket.
2006.

21
Mesial and Distal Movement
× For mesial movement of the teeth space has to
be created by placing blockout material, on the
mesial side of the tooth to be moved.
× The force - indentation or placing a bump in the
thermoplastic with a thermoplier on the distal
side.
× Space must be in proportion to the amount of
tooth movement.
× The block out relief must be even with, or slightly
above, the incisal edge, if not the incisal edge will
contact the inside of the Essix appliance, and
interfere with tooth movement
Orhan.C.Tuncay. The Invisalign system. First edition 2006.

22
Tipping
× If an incisor is to be tipped lingually the
bump is placed on the center of the labial
surface of the appliance.
× The relief would cover the entire lingual
surface of the working cast.
2006.

23
Rotation
× If rotation is needed on both side, in
opposite directions, it is necessary to
induce a force(bump) one side and
relief on opposite side.
force
Relief
2006.

24
Intrusion with Essix appliance
× Thermoforming Essix plastic over the
unaltered cast.
× The plastic covering the crown of the
tooth to be intruded is cut off at the
cervical line
× On the facial and the lingual of the
plastic gingival to the tooth elastic
attachment tabs are made.
× A rubber band should be stretched
from one attachment tab to the other
so that it crosses the crown of the tooth
to be intruded.
2006.

25
Extrusion using Essix appliance
× It is done using sling shot method
use of elastics which involves
anchoring an elastic on each side of
the tooth to be extruded.
× The elastic as it returns to resting
state induces an extrusive force on
the target tooth.
× Force used should be no more than
50 gms.
2006.

Invisalign is the invisible way to straighten teeth without braces.
Invisalign uses a series of clear, removable aligners to gradually
straighten teeth. 26

× Kelsey Wirth and Zia Chishti, two MBA students
from Stanford University, founded Align Technology
in April 1997
× Invisalign takes the principles pioneered by Kesling,
Remensnyder, Sheridan, and others and integrates
CAD/CAM technology.
27

× The concept on which
the company was
founded came from
Chishti, who underwent
adult orthodontic
treatment.
× After the treatment he
was not consistent in
wearing his clear
retainers.
× He developed
recrowding of his
mandibular teeth,
Chishti returned to
wearing his overlay
retainers which
realigned his teeth.
× He came up with the
idea of using multiple
appliance and
computer imaging
technology to effect
major tooth
movements.
28

• Esthetics
• Comfortable
• No Reported Root Resorption
• Less Discomfort and Pain
• Operator controlled movements
.
29

× Compliance Dependent
× All permanent teeth should be fully erupted /
Short clinical crowns
× Treatment plan cannot be changed once begun.
× Expensive.
30

× Initial consultation
× Records
× Polyvinyl Siloxane
impression
× Treatment planning form
32
Clinician’s
office
Align
Technology
• Impression
scanned
• Treat software
process
• Clincheck.
Align
Technology
Clinician’s
office
Shipped
ClinCheck via internet
Acceptormodify
Shipped

Invisalign treatment is based on the patient records acquired
by the clinician.
Five different records are necessary to create a "virtual
patient"
1. Impressions of the maxillary and mandibular dental
arches,
2. Bite registration,
3. Intraoral and extraoral photographs,
4. Panoramic and full-mouth series radiograph, and
5. The prescription and diagnosis form.
33

Taking
impressions -
Best practices

Putty Impressions - How to Take Two-step Impressions

Disinfection of impressions
× Before shipping the impression should be
disinfected.
× Polyvinyl siloxane (PVS) impressions can be
disinfected by a variety of disinfectants like
glutaraldehyde, iodophor, and phenols as
per the manufacturer's directions.
36

38
A study from 2014 found that the use of intraoral scanners could significantly accelerate the work
flow of making impressions.
 More comfortable for patients than conventional
impressions
 Save costs on impression materials
 No shipping hassles
 Higher accuracy than traditional impressions
 Fewer errors resulting in having to re-impress
 Facilitates sending scans electronically, resulting in
a faster turnaround
https://support.clearcorrect.com/hc/en-us/articles/115004919647-Intraoral-scanning
Benefits of using an intraoral scanner include
The time efficiency of intraoral scanners -Patzelt, Sebastian B.M. et al.
The Journal of the American Dental Association, Volume 145, Issue 6, 542 - 551

A good impression has proper identification of tooth
anatomy and the manufacture of aligners that fit
properly.
After the impression is scanned, it is inspected by Align
technicians.
The impression should extend more than 2 mm beyond
the free marginal gingiva on the buccal and lingual
surfaces.
If any minor discrepancies are present in the impression
then the technician can see the photographs and
make some modifications.
The most common mistake is incomplete or partial
recording of terminal molars.
40

41
× Photographs: The doctor should supply 8 digital photographs of the patient
in jpeg format.

44
1. Obtaining diagnostic information regarding the patient's restorations,
caries, skeletal form, and the condition of the dentition and surrounding
bone structures.
2. Radiographs can reveal the presence of crowns, and implants that may
not be shown on photographs.

Prescription and Diagnosis
Form
× Communication between the treating clinician and
Align Technology technicians.
1. Arch(es) treated,
2. Diagnostic setup,
3. Teeth not to be moved,
4. Overbite and overjet goals,
5. Handling of tooth size discrepancies, and other
general preferences.
45

LABORATORY AND
TECHNICAL PROCEDURES
 Impressions scanning
 Preparation of virtual dental models
 Virtual bite registration
 Tooth separation (on the virtual models)
 Staging of tooth movements
 Elaboration of clincheck
 Clincheck review by clinician (approve or
modify)
 Aligners production and delivery 46

The clinician ships all the 5 records
A 3-dimensional virtual treatment .
Acquisition or scanning is used to describe the process of converting
a physical object into 3 dimensional electronic data.
1. Laser scanning
2. Destructive scanning
3. Computerized tomograph
4. White-Light Scanning
47

49
Tooth separation (on the
virtual models)
In early 1997, the software component of the
Invisalign process was broken into two parts:
1. Modeling and
2. Moving the teeth.

Modeling:
A 3-D model is created that looks very similar to a dental cast
.
This surface, small triangles.
50
The surface is composed of many
small triangles

Two corresponding software were created for tooth
movement(1997):
1. Clipper - used to "cut" a virtual dental model into multiple pieces, each one
representing a tooth.
2. Aligner-Taking the virtual model created by Clipper it allowed the user to move
the teeth into a final position.
Over time, these 2 programs were eventually
merged into a single application called Treat
(2002).
51

.
1.Tooth shaper
× Technician verifies that the quality of the records and begins
to cut the teeth using Toothshaper software.
× If the impression is of poor quality, the technician calls the
clinician to request another impression.
52
Treat software

.
A. Identifying and marking
the facial axis of the
clinical crown (FACC)
of each tooth using a
point on the incisal
edge and a point on the
cementoenamel
junction.
× This helps in estimating
the shape and
angulation of the teeth.
B. The next step is to
detail any imperfections in
the impression (i.e., fill
voids, remove excess
material, correct
deficiencies in the scan
model).
53
Two basic steps

54
× Painting tool gives each tooth a color to
discriminate between them.
× Once each tooth has been identified
the technician simply clicks a button to
segment the teeth.
2.Painting tool

Then the technician prepares the models for
the setup process
× This begins by setting the axis or widget
of each tooth.
× The axis or widget are set in the X, Y, and
Z directions, which enables the technician
to easily move the teeth in the desired
position when performing the virtual
setup.
55
3.Axis

56
× The Treat software adjust the
virtual gingiva to replicate the
patient’s actual gingival tissue.
× Proper gingival adjustment is
required for a good fitting.
4.virtual gingiva

57
× After segmenting , detailing, and setting of the axis have been
completed, the bite is set in centric occlusion using an Auto
Bite tool in the Tooaper software and confirms the result
with the photo.
5.Bite Tool

Final Setup and Staging
The setup and stage technician reads the prescription form submitted by the
clinician to know how the case should be treated.
Invisalign's Treat software performs this function.
The process of specifying tooth movements is broken into two steps:
a. Specifying the final position of the teeth and
b. Specifying the paths that each tooth will take between its initial and
final positions.
58

,
59
BoltonAnalysis Tool
× The Bolton analysis tool calculates the tooth size discrepancy
that is present in a case.
× The Bolton analysis displays the anterior and overall
discrepancy.

.
60
Tooth Motion Information Window
× The Tooth Motion Information window provides a review of
the clinical information on the linear movements plus the
rotation of the teeth around its long axis.

Arch Information Tool
When one of the arches is selected in the Treat software, the Arch
Information tool allows the technician to visualize descriptive
information such as arch length, perimeter, intercanine width,
and intermolarwidth.
61

ANCHORAGE
Cases can be staged as low-anchorage pattern or a high-
anchorage pattern based on the doctor's prescription and
diagnosis form, and also based on the internal staging
protocols that the technicians follows.
62

63
× After the case is staged, the virtual setup contains information
like how many stages or steps are required, the velocity at which
the teeth are moving and the timing of the movements for each
particular tooth.
× The technician converts the Treat software data to ClinCheck
software data.
Orhan.C.Tuncay. The Invisalign system. First edition 2006

× The ClinCheck file is a three-dimensional (3-D) virtual
representation of a clinician's prescribed treatment plan
× It has two components
.
1st component- It is a series of computerized graphic images
of the patient's teeth showing several stages of movement,
from initial to final position.
2nd component- Pressure formed clear plastic appliances
made from STL models of images of 1st component.
64Orhan.C.Tuncay. The Invisalign system. First edition 2006

The ClinCheck is sent via the Internet
to the clinician for review, and the
clinician can communicate back to
the Align technician to accept the
ClinCheck or request any changes.

× The first step in the production of an aligner is the
acceptance of the planned treatment by the submitting
clinician through ClinCheck.
× The rapid manufacturing process currently used at Align
Technology is known as stereolithography (SLA).
× The computer images are converted to physical models
by using a process called stereolithography
× These models are then used to fabricate the aligners on
a Biostarpressure molding machine
66

67
× SLA selectively exposes a
photosensitive epoxy resin, layer by
layer, using laser optics to generate
models based on the Stereolithography
data.

.
× Afterwards the molds
are removed from the
machine and transferred
to an automated post
processing line, where,
excess uncured resin
and debris are removed.
× The platform is then
automatically
transferred to an
ultraviolet (UV) curing
station to completely
cure them.
2006

× All molds created at Align has some
embedded tracking features in it for
identification.
1. Readable text is engraved on the side of the
mold to indicate the patient identification
and the stage number.
2. Two-dimensional bar code information
which contains similar information.
69
2006

70
× These models are then used to fabricate
the aligners on a Biostar pressure molding
machine.
× The aligners are trimmed and laser-etched
with the patient’s initials, case number,
aligner number, and arch (upper or lower).
× They are then disinfected, packaged, and
shipped to the doctor’s office.
2006

Aligner Materials
Invisalign appliances are fabricated from a polyurethane material
1. 0.030-inch thickness (Ex30)
2. 0.040 inch thickness (Ex40).
Ex30- initial correction stage till the early stages of tooth
movement.
Ex40 - end of treatment to slightly improve the alignment
used during the retention stage.
3. SmartTrack® material
innovative multi-layer polymer that delivers more gentle,
constant force to improve control of tooth movement

72
× Traditional orthodontic appliance systems are designed around components
that transmit forces (i.e., wires) and elements that apply these forces (i.e.,
brackets) to the teeth.

73
× The Invisalign System also follows
this design where aligners are
analogous to wires and
attachments are equivalent to
brackets.
2006

74
× Attachments are composite geometries that are bonded to the facial or
lingual surfaces of the teeth to create undercuts to help facilitate
maximum adaptation of each aligner to the teeth and help avoid aligner
displacement, so that the movements programmed into each aligner can
be fully expressed.

75
SmartForce attachments:
•Are tiny and barely noticeable
•Make complex tooth movements possible without
braces
•Help aligners apply the right amount of force in the
right direction

76
× An attachment is readily identified in a
ClinCheck presentation as a red
geometric body that lies on one or more
tooth surfaces.
× The attachments placed in the virtual
setup are built into the resin models for
each aligner stage.

77
× An attachment template (thin-material
aligner) is created to transfer the exact
shape and position of the attachment
from the 3-D model to the actual tooth.
× The clinician fills each attachment
reservoir in the template with
restorative dental composite and then
place it on the tooth and cures the
composite.

78
× There are three types of attachment:
1. Movement Attachments
2. Retention Attachments, and
3. Auxiliary Attachments.
× All three act as force transmitters however, they do so in different ways.
1) Movement Attachments
• Intended specifically to induce or
aid the repositioning of the teeth to
which they are bonded.

79
2) Retention Attachments
× Factors such as short clinical crowns,
insufficient undercuts, missing or extracted
teeth, and pronounced tooth-size
discrepancies, necessitates the need for
additional retention for the appliance to be
stable.

80
a) Force augmentation
× During appliance fabrication plastic thins
in the maxillary central incisor area.
× Thickening the plastic over the centrals
would tend to make the region stronger.
× This can be achieved by placing rigid
attachment across the interproximal
region.
3)Auxiliary Attachments
Attachments have numerous applications as auxiliary treatment elements.

81
Fixation points
× Fixation points is created when
aligners are used as surgical splints.
× These help in tying the jaws
together through them during
postoperative healing.
2006

Intrusion
Anterior teeth
× When dental intrusion is programmed into the
aligners, an occlusal interference is naturally
created that unseats the aligner from the
posterior teeth unless attachments are placed on
the posterior teeth to help anchor the aligner.

.
× Once attachments are placed to prevent the
separation of the aligner from the posterior
teeth, the aligner is able to deliver a vertical
force to intrude the anterior teeth.
83

.Posterior teeth
× When attempting to intrude posterior teeth, it is
important that the interproximal surfaces of the
intruding tooth be clear from the adjacent tooth
surfaces to avoid tooth-to-tooth collision.

.
Rotation
× The aligner is prone to slipping along the facial and lingual
surfaces as it tries to derotate the tooth.
× Placement of buccal and lingual attachments is designed to
create aligner purchase points for improved tracking during
tooth movement.

.
Translation
× To achieve root translation and avoid tooth tipping,
orthodontic force must be generated near the gingival area
of the tooth.
× Rectangular attachments can be used in this circumstance
because the sides of the attachment create additional
surface contact with the aligner near the gingival third of the
tooth.

87
× Overcorrection is not necessary as the
retention aligners will hold the teeth in
position.
× If any minor alignment discrepancies at the
end of treatment is noticed, this can be
handled by using Invisalign detail pliers to
generate additional orthodontic forces in
the aligners.

88
× The plunger and recessed stop
at the tip of the detail pliers
create a permanent bump in the
aligner which create a force.
× In case if the bump is positioned
in the wrong location then an
eraser pliers can be used to
flatten the formed bump.

× Invisalign in orthognathic surgery cases can be used
as an appliance and as a diagnostic tool (ClinCheck)
to help plan the patient's surgery and orthodontic
treatment.
× ClinCheck offers the orthodontist a new way of
viewing treatment goals.
× ClinCheck is model based that is, created from an
impression of the teeth without the reference of the
skeletal base, it can provide simulations that will
help with the diagnostic process.
89

90
Combination therapy
× Some clinicians prefer to use fixed appliances before
Invisalign, and others opt for Invisalign first.
× Align technology advices to use Invisalign until 4
months before surgery and then fixed appliances until
6 months after surgery and if necessary again
Invisalign.
2006

Mandibular Advancement Feature
91
Invisalign clear aligners with mandibular
advancement:
•Straighten the teeth.
•Have precision wings that push the jaw forward.
•Mandibular advancement can fix class II malocclusions
in tweens and teens.

Instructions
92
• Take aligners out to eat and drink, then brush teeth before
putting them back in.
• Wear clear aligners 20 to 22 hours a day for best results
• Each set of aligners for one to two weeks, as prescribed by
doctor.
• Schedule check-ups every six to eight weeks to check your
progress and pick up the next batch of aligners.
• When patient start wearing each new set of aligners, they may
feel a little extra pressure or discomfort for the first few days, which
is totally normal
•Rinse aligners every night and brush them gently with your
toothbrush to keep them fresh and clean.
•Use the aligner cleaning system to keep aligners clear.

93Creative Adjuncts for Clear Aligners, Part 1: Class II Treatment S. JAY BOWMAN DMD, MSD jco

95
Segmental Multiple-Jaw Surgery without Orthodontia: Clear Aligners Alone, Hadyn
K. N. Kankam et al Plast Reconstr Surg. 2018 Jul;142(1):181-184. doi:
10.1097/PRS.0000000000004491.

× These esthetic appliance is a boon for us in many
ways
× Our job us a clinician is to have a realistic treatment
goals .
× The future orthodontists may need to carry
armamentarium for a labial, lingual and clear aligner
systems.
96

98
1) Orhan.C.Tuncay. The Invisalign system. First edition 2006.
2) Essix Appliance Technology: Application, fabrication, and Rationale.
John. J. Sheridan and Keith Hilliard.
3) Profitt, Contemporary orthodontics, Fourth Edition.
4) Kesling HD. The philosophy of tooth positioning appliance. Am J
Orthod 1945; 31:297–304.
5) Ponitz RJ. Invisible retainers. Am J Orthod 1971; 59(3):266–273.

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