The very need for orthodontic treatment by a majority of adult patients is derived with a desire for enhancement of dental alignment and facial aesthetics. Although buccal fixed metallic appliances are efficient treatment systems, the reluctance of their use is mainly due to metal look, poor aesthetics and fear of pain. Clear plastic aligners’ offer an excellent alternative to unaesthetic orthodontic treatment with labial fixed appliances The clear aligner appliance(s) is nearly transparent, colourless and almost invisible. As these devices are removable, they allow the patient an additional option to be without braces for social and professional engagements. The oral hygiene is not a problem with this appliance and most patients adapt to it very quickly. The success of these types appliances is intimately related to the compliance in wearing the appliance for a minimum number of hours and following the required schedule of changing the aligners as per sequence assigned to the case. Patients are asked to wear the aligners for a minimum of 22 h/day. Thus, patient compliance is paramount in clear aligner therapy. Some of the patients seeking clear aligner treatment are those who have previously received orthodontic treatment using fixed appliances and have had a relapse or are unsatisfied with treatment outcome.

1. Clear Aligner Treatment
Guided by- Dr. Jeevan M. Khatri sir
(Professor & HOD)
Dept. of Orthodontics and Dentofacial Orthopaedics
Presented by- Dr. Krutika A. Patankar (2nd YR MDS)

2. Contents:
• Introduction
• Historical aspects
• CLEAR ALIGNERS apart from Invisalign
• Overview of steps in clear aligner treatment
• Case selection and records
• Virtual setup
• Clincheck
• Clinical management.

3. Introduction
• The very need for orthodontic treatment by a majority of adult patients is derived with a desire
for enhancement of dental alignment and facial aesthetics. Although buccal fixed metallic
appliances are efficient treatment systems, the reluctance of their use is mainly due to metal
look, poor aesthetics and fear of pain. Clear plastic aligners’ offer an excellent alternative to
unaesthetic orthodontic treatment with labial fixed appliances
• The clear aligner appliance(s) is nearly transparent, colourless and almost invisible. As
these devices are removable, they allow the patient an additional option to be without
braces for social and professional engagements. The oral hygiene is not a problem with
this appliance and most patients adapt to it very quickly. The success of these types
appliances is intimately related to the compliance in wearing the appliance for a
minimum number of hours and following the required schedule of changing the aligners
as per sequence assigned to the case. Patients are asked to wear the aligners for a
minimum of 22 h/day. Thus, patient compliance is paramount in clear aligner therapy.
• Some of the patients seeking clear aligner treatment are those who have previously
received orthodontic treatment using fixed appliances and have had a relapse or are
unsatisfied with treatment outcome.

5. Historical Aspects:
• You will be surprised to learn that it took almost hundred years to develop the invisible
braces that are being used in the modern days. Here is a phase by phase evolution of the invisible
braces that will provide you with a knowledge of how these tooth aligners were developed and
modified until the invisible braces came into use.
• 1925 – The origin of the dental aligners dates back to 1925 when the ‘Flex-O-Tite’ gum massaging
appliance was invented by Orrin Remensnyder for the treatment of dental diseases like
periodontitis. A slight movement of the teeth was noticed as a side effect.

6. • 1946: KESLING CREATED TOOTH POSITIONER : 20 years down the road in 1946, Kesling invented
his ‘tooth positioner’ which was made from an elastic vulcanite plastic. It was meant to be used
after the orthodontic treatment along with fixed appliances, like dental brackets. The
‘Positioner’ was made based on the ideal position for teeth by way of a cast model at the end of
the treatment, and he found that significant movements could be achieved. Somewhat ahead of
his time, he remarked in his notes the following:
"Major tooth movements could be accomplished with a series of positioners by changing the teeth
on the setup slightly as treatment progresses. At present this type of treatment does not seem to
be practical. It remains a possibility, however, and the technique for its practical application might
be developed in the future."

7. • 1964: NAHOUM’S PLASTIC SHEETS:It wasn’t until 1964 that Dr. Henry Nahoum would build on
Kesling’s idea, albeit with a twist. Nahoum created a method using thermoformed plastic sheets
to move teeth ("The Vacuum Formed Dental Contour Appliance"). This was arguably the first
dental ‘aligner’ to be produced, but Nahoum found that the process was somewhat limited
because of the difficulty found in evenly dividing larger movements into small precise stages.

8. • Sheridan et al. introduced the concept of interproximal tooth
reduction (IPR) for resolution of the lower incisor crowding and alignment of
teeth with the help of labio-lingual clear plastic retainer. His appliance is named
‘Essix appliance’. The method adopted by Sheridan required newest of dental
study model to fabricate each appliance, making this technique cumbersome and
time-consuming for patient, orthodontist and laboratory technician alike.

9. • 1997: ALIGN TECH, GOING MAINSTREAM:In 1997, two MBA students put
together a business plan for what would later become Invisalign. If Remensnyder
was the one creating the concept, Kesling/Nahoum were the ones who began
using it as a treatment method, and Sheridan was the one to clinically validate it,
then it was Align Tech that popularized dental aligners.

10. CLEAR ALIGNERS apart from Invisalign
• CLEAR CORRECT
• BYTE
• CANDID
• ALIGNERCO
• SMILE DIRECT CLUB
• SIX MONTHS SMILE
• INVISALIGN EXPRESS

11. • It is important to understand that clear aligner treatment is a
technique, not a product.
• Certain terminologies associated with Clear Aligner.
• A MIDCOURSE CORRECTION
• REFINEMENT
• INTERPROXIMAL REDUCTION
• ATTACHMENTS

12. Overview of steps in clear aligner treatment
1. Case records and case selection
2. High-quality impressions or intraoral scans
3. 3D virtual set-up and treatment progress stages
4. Approval of treatment steps on the web
5. Construction of aligners’ delivery to treating doctor. Issue of aligners
and review
7. Finishing and retention

13. A COMPARISON BETWEEN EDGEWISE APPLIANCES
AND CLEAR ALIGNERS
• Clear aligner treatment is an orthodontic technique. As such, the
orthodontic principles of force application, engagement, anchorage,
and biomechanics need to be applied to clear aligner technique.
However, clear aligners move teeth differently than fixed appliances
do. Therefore, a clear understanding of the similarities and
differences between fixed appliances and clear aligners is essential for
the clinician when making a decision whether to treat a case with
fixed appliances or clear aligners. Clear aligners are uniquely suited to
treat some malocclusions more efficiently than fixed appliances,
offering better vertical control and superior management of
anchorage considerations. Knowing the strengths and weaknesses of
clear aligners as an orthodontic appliance will assist the clinician in
selecting the best orthodontic appliance to address a specific
malocclusion.

14. FORCE
• A fundamental difference between the way a bracket and wire system
moves teeth and the way clear aligners move teeth is that fixed
appliances pull on teeth while clear aligners push on teeth.

15. Engagement
• Fixed appliances engage teeth via an archwire ligated into the bracket slot. The thicker and more
rigid the archwire, the better the engage- ment. The archwire sequence starts with round, flexible
archwires with a long working range and high elasticity and gradually moves toward rigid,
rectangular stainless steel archwires.
• Clear aligners engage teeth by having align- er material wrapped around teeth. The more aligner
material wrapped around a tooth, the better the engagement.

16. ANCHORAGE
• In fixed edgewise appliances, the most common anchorage model is
that of reciprocal anchorage, based on Newton’s third law: For every
action, there is an equal and opposite reaction.
• In clear aligner treatment, the anchorage segments can be
predetermined and may change at different stages in treatment.

17. Capabilities of fixed appliances versus clear aligners in terms of
extrusion, intrusion, torque, and root inclinations

19. Relative intrusion with a reverse curve in the
archwire.

20. (a and b) Superimpositions in the software program showing anterior
intrusion to level out the curve of Spee.

21. (a and b) Superimpositions in the software program showing
posterior intrusion to create occlusal clearance.

22. Power ridge feature for incisor torque on maxillary and
mandibular incisors.

23. Optimized root control attachments for control of
root inclination.

24. Capabilities of fixed appliances versus clear aligners in terms of
incisor inclination, vertical control, midline correction, and tooth
size discrepancy

25. • Traditionally, orthodontists are trained to be reactive. An adjustment
is made to the appliance and, based on the patient’s treatment
response and the resultant tooth movement, another treatment
decision is made at the next appointment and the archwire adjusted
accordingly. Each treatment decision is made reactively, based on the
treatment response to the adjustment to the orthodontic appliance
made previously.
• Clear aligner technique requires a more pro- active, disciplined
approach. Before a single tooth is moved, the correction of the
malocclusion is visualized through a series of tooth movements made
on a software program and the final occlusion designed into the
treatment outcome. This requires a paradigm shift in the thought
process from being a reactive orthodontist to being a proactive
orthodontist.

26. Case selection: Arch length discrepancies

27. Vertical discrepancies

28. Transverse discrepancies

29. Techniques for the treatment of dental AP discrepancies and
their respective degrees of difficulty.

30. Techniques for the treatment of skeletal AP discrepancies and
their respective degrees of difficulty

31. Indication for clear aligner treatment

32. • Steps and treatment stages with Invisalign system of clear aligners
• 1. A collection of high-quality records. The pre-treatment records are
obtained for documentation and purpose of comprehensive diagnosis
and treatment planning. The essential records include extra and
intraoral photographs, lateral (and PA if required) cephalograms OPG
and relevant X- rays. High quality impressions are obtained with a
polyvinylsiloxane material. The bite is also recorded. The impressions
are sent to the Invisalign office. Since 2007, the iTero scanner, has
replaced the need for traditional dental impressions. In 2013, Align
Technology introduced the iTero imaging system available as a single
hardware platform with software options for restorative or
orthodontic procedures. It has a direct connectivity with Invisalign
and has the option to show patients the outcome of their Invisalign
treatment.

33. • Treatment success begins with a high-quality polyvinyl siloxane (PVS)
impression. Initially, Align Technology used a process called destructive
scanning to produce the three-dimensional (3D) digital image of the
patient’s teeth. It involved pouring the impressions with plaster to produce
a conventional 3D model. Those models were then “scanned” using a
destructive technique whereby the model was photographed from the
occlusal view, milled down slightly, photographed again, milled down some
more, photographed again, etc.
• The destructive scanning method had the advantage that a lab technician
could fix minor imperfections in the impression by repairing the model
prior to scanning. The disadvantage was that it was expensive and time
consuming and produced huge quantities of plaster dust. Align Technology
no longer uses the destructive scanning technique but converts the
impression directly into a 3D virtual model by means of a high-resolution
industrial computed tomography (CT) scan. The special plastic impression
trays must not interfere with the x-ray scanning and there is no plaster
model intermediary on which a lab technician can repair defects, so the
impressions must be perfect.

34. There are three basic impression techniques:
• The easiest but most likely to result in defective impressions involves a one-step
impression using a suitable “medium body” PVS material in the proprietary
Invisalign impression trays. Many orthodontists prefer this method because of the
potential for reduced chair time and expenses. The problem with this one- step
technique is that there is a higher probability of missing the critical anatomy of
one or more teeth, especially the areas distal to the second molars which are
required for proper fit of the aligners.

35. • The second impression technique that can be used is a combination
technique wherein impressions of the second molars are first
captured using a PVS putty material to create a posterior dam. The
medium body material is used over the putty to gain a more detailed
impression of the second molars, as well as to capture the rest of
dentition.

36. Putty technique final.

37. • The third impression technique involves a more involved two-step
process. The first step involves making custom trays and Essix-type
retainers that we later describe to the patient as “training aligners.”
When the patient elects to start treatment, an alginate impression is
taken of both arches. The patient is then scheduled to return for final
impressions. The rest of the first step is completed in the laboratory.
The impressions are poured up in the office using standard dental
stone and trimmed as though they were to be used to make Essix-
style retainers

38. Models with thermoformed plastic material in
place.

39. Models with thermoformed plastic sheet inverted
into heavy body material.

40. Completed custom trays.

41. A, B, Custom trays with light body wash ready for
final impression.

42. Completed final impression

43. • Troubleshooting Problems with Impressions
• The aligner fit is only as good as the quality of the impressions.
• The most common shortcoming with impressions is failure to capture
sufficient detail of the distal of the second molars
• A common error is multiple areas of “drag” near the gingival margin.
These are triangular voids caused by seating the tray with impression
material too quickly into the mouth and not allowing sufficient time
for the material to flow around the gingival margins. This is a critical
error because there is no way to have the appliances properly
trimmed for comfort and effectiveness if the gingival margins cannot
be identified. This can be avoided by seating the impression tray more
slowly

44. Drag defects near gingival margins.

45. • A third common error involves surface or immediate
subsurface air bubbles in the impression. These are created
either by capturing air in folds of the material while loading
the tray due to moving the syringe tip in and out of the
material or by seating the impression tray too quickly into
the mouth and trapping air between the tooth and the
material. If the air bubble is immediately below the surface
of the impression material, the impression may appear to be
of good quality, but when it is scanned with the CT, the PVS
material may not be of sufficient thickness to be resolved on
the image and the tooth will have a large area of distortion
on the virtual model. Both these errors can be avoided by
using proper technique.

46. Air bubbles in the impressions.

47. • The last common error is seating the impression tray too far from or
too close to the buccal or lingual tooth surface so that the impression
material bleeds through to the impression tray and the material
becomes too thin to be resolved on the CT image. These errors
produce a virtual model with the same problems as an air bubble.
This can be avoided by using the correct size impression tray and
seating it properly in the mouth. It should be noted that the
impression trays that are provided by Align Technology are plastic and
are easily customized to the patient by heating the tray and forming it
to the individual patient’s arch form

48. Impression tray bleed through.

49. • The Virtual Setup
• When the impressions arrive at Align Technology in Santa Clara,
California, they are scanned using an industrial CT scan to produce a
3D virtual model. The technician uses a best-fit occlusion based on
wear facets and virtual contacts along with the intraoral photographs
provided in the submission kit to articulate the models.
• It is important to understand that the occlusal registration sent with
the impressions is used to verify the occlusion only if the photographs
are of poor quality

50. A–C, Three-dimensional virtual models generated
from CT scan of PVS impressions.

51. • Once the virtual models are produced, they are segmented using
Boundary recognition software to define individual teeth. It is
important to remember for future discussion that the impression
generally does not capture the interproximal surfaces of the teeth, so
the software must interpolate that information and estimate the loca-
tion of interproximal surfaces and contact areas. Once that is
accomplished, virtual “roots” are placed

52. • The technicians recreate the virtual gingival margins using morphing-
type software to mimic the gingival conditions seen on the clinical
photographs

53. • The preparation work is finished at this point, and the virtual model is
forwarded electronically to the TREAT (Align Technology, Inc.)
operator to perform the virtual setup and staging. TREAT is the
proprietary software that Align Technology uses to simulate
treatment and set up the virtual model to allow the manufacture of
the aligners. It is a sophisticated 3D graphics program that gives the
operator great control of tooth position and rate of tooth movement.
It is not the software that the orthodontist uses to view the virtual
model, which is called ClinCheck (Align Technology, Inc.).Once the
virtual setup is completed and approved by the orthodontist, a series
of plastic models is fabricated using stereolithography on which the
aligners are then made by a thermoforming process.

54. Direct Digital Manufacturing
• Due to the time and expense of producing PVS impressions, shipping them
to Align Technology, scanning them once received, and subsequent
processing of the image data into a usable format, there is emphasis on
finding a method of direct digital conversion of the dentition into a usable
3D image. Currently, there are two promising technologies: cone beam CT
(CBCT) and intraoral light scanners. Both of these technologies have the
potential of producing an image that would be of a sufficiently high quality
that the orthodontist would be able to capture the image directly in their
office and then electronically transmit that image to Align Technology to
have the appliances made.
• The advantage of direct digital capture of the dentition would be (1) the
elimination of the need for PVS impressions and their inherent potential
for clinical errors and (2) reducing the time needed to produce appliances
because the image would be transmitted instantly to Align Technology via
the Internet. There are still multiple challenges remaining with both
approaches. However, prototype appliances have been made using both
techniques and it is likely that one or both approaches to direct digital
manufacturing will be available in the future.

55. Clincheck
• The clinicians download the virtual treatment set-up, stage by stage
at the dedicated Internet site and if required request for modification
of treatment/tooth movement sequence. This step is called ‘Clin
Check’. In 2016, Invisalign launched the new Clin-Check Pro 6.0 that
provides a 3D modelling of the whole treatment

56. • Once the step-by-step progress of the patient’s treatment is reviewed by
the treating doctor, he may ask for any changes at this stage concerning the
sequence of tooth movement or plan of the treatment. Once precise
treatment plan and course of tooth movement has been finalised, the
aligners are made and dispatched to the Orthodontists.
• The number of Aligner made may vary.
• Clinical management with Invisalign aligners. Some aligners
• for a patient vary according to the severity of the malocclusion. Invisalign
offers the following treatment modalities:
• a. Invisalign Full: It is the most commonly used course of therapy.
“Invisalign Full” is used for treating complex malocclusion conditions.
• b. Invisalign Lite: Providing for less complex alignment problem cases,
Invisalign Lite uses up to 14 aligners.
• c. Invisalign i7: This was developed for the cases of minor dental
corrections. It comprises up to seven aligners.
• d. Invisalign Teen: With teenagers, there is commonly a period of rapidly
shifting changes occurring as they grow. Invisalign Teen was developed to
help accommodate these issues with some special features.

57. • Historically, each aligner was supposed to be worn for 2 weeks, and
patient visits the doctor every 4–6 weeks. The new G7 features,
introduced in 2016, allow the patients to change aligners every week.
However, it is the practitioner’s discretion and the type of movement
required which decides the schedule of change of the aligners. The
appliance is recommended to be removed during eating and to brush
the teeth. The patient should be warned to safeguard the appliance
as its chance of being lost is great due to its colour-less structure.

58. To be continued….