- Invisalign is an orthodontic technique that uses clear plastic aligners to gradually move teeth over time. It was introduced in 1998 and involves wearing a new set of aligners for 2 weeks and replacing them every 2 weeks. - Studies have found that Invisalign has a lower success rate and takes longer than traditional braces. It is also more expensive. However, Invisalign is aesthetically pleasing and causes less pain than braces. - Invisalign works best for minor malocclusions like crowding or spacing less than 5mm. It is not recommended for more complex cases like open bites or severe rotations. Regular monitoring by the orthodontist is needed to ensure the treatment is on track.

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Clear aligner appliances
Invisalign
History
• The idea originally described by Sheridan in 1980 and 1990
• The Invisalign system was introduced by Align Technology (Santa Clara,Calif) in
1998.
Philosophy
• It is an orthodontic technique used a succession of clear aligner to position the teeth
• It is used 24/7 and replaced every 2 weeks with aiming to move the teeth by 0.25mm
each time.
• The system uses CAD/CAM stereolithographic (STL) technology to predict
treatment outcome and creates custom made aligners from a single impression
Evidences
• Align Technology would suggest that 20-30% of patients may require mid-course
fixed appliance orthodontic appliance correction to achieve the predicted treatment
outcome.
• Many orthodontists, however, report that 70-80% of patients require case refinement
and /or detailing with fixed appliances.
• The mean accuracy of Invisalign for all tooth movements was estimated at 41% in a
recent prospective clinical study, Kravitz 2009
• Djeu et al 2010 retrospective comparison of outcomes of non-extraction Invisalign
and fixed appliance treatments, using the ABO objective grading system (1998), found a
significant difference in the pass rate of Invisalign compared to Tip-Edge treatment
(20.8%, 47.9%, respectively) and the time for Invisalign at 1.4 years compared to 1.7
years for Tip-Edge treatment. So Invisalign is shorter in the duration of treatment BUT
with poor outcomes and expensive!!!!!! The reason why it is shorter in time because they
are moving the teeth without round tripping to the defined final position
• Lagravere 2005 systematic review, The inadequately designed studies the authors
found represented only a lower level of evidence (level II). Therefore, the authors found
that no strong conclusions could be made regarding the treatment effects of Invisalign

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appliances. Future prospective randomized clinical trials are required to support, with
sound scientific evidence, the claims about Invisalign's treatment effects. Clinicians will
have to rely on their Invisalign clinical experience, the opinions of experts and the
limited published evidence when using Invisalign appliances.
Classification of invisalign system
(Malek 2013)
A. Invisalign Full
Maximum flexibility in treatment of a wide range of malocclusions
B. Invisalign Teen
• Treatment for teenager patients.
• The device has unique Innovative features that address patient compliance.
C. Invisalign Anterior
Treatment limited to moving upper and lower anterior teeth (canine to canine) with
crowding or spacing of 4 mm or less per arch
D. Invisalign Lite
Treatment for
• minor crowding or spacing
• orthodontic relapse
Only allows use of 14 aligners or less
E. Vivera Retainers
Retainer made by Invisalign at the end of treatment
Indication of Invisalign
• Mild crowding and mal-alignment problems (1-5 mm).
• Spacing (1-5 mm).
• Deep overbite problems (class II division 2) where the overbite can be reduced by
intrusion and advancement of the incisors.
• Narrow arches that can be expanded without tipping the teeth too much.
Contraindication of Invisalign
• Crowding over 5 mm.
• Spacing over 5 mm.
• Anterior-posterior discrepancies of more than 2 mm.

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• Open bite correction.
• Severely rotated teeth more than 20 degrees.
• Severely tipped teeth, more than 45 degrees.
• Teeth with short clinical crowns.
Advantages of Invisalign
• Ideal aesthetics.
• Less pain
• Improved periodontal health due to cleansibility.
• Less decalcification
• Less OIRR
• Shorter treatment duration
Disadvantages of Invisalign
• Poor control over root movements resulting in problems with root parallelling,
severe rotations, tooth uprighting and extrusion.
• Not suitable for the use in anteriorposterior discrepancies greater than 2 mm as
intermaxillary correction is very limited.
• Lack of operator control. Once the treatment is underway and the aligners have been
made, if changes to treatment are needed new impressions and aligners will need to be
produced.
Process of Invisalign manufacturing
Goffe, 2003
http://www.youtube.com/watch?v=u19Xka-g9WU
• Impressions must be taken with poly-vinyl siloxane (PVS) due to its superior
accuracy and stability.
• PVS bite registration,
• Photographs (both intraoral and extraoral)
• Radiographs
Send to USA
• The PVS impressions and bite registration are scanned by x-ray to create accurate
three-dimensional digital models, registered in maximum intercuspation.
• Removes artefacts from digital model.

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• Digitally separate the teeth and add gingiva around them.
• Moves the teeth to their final positions in a series of stages according to the doctor’s
prescription.
• Doctor for approval
• A series of casts are created using stereolithography
• Clear plastic aligners are made from these casts and sent directly to the doctor.
• Composite attachments bonded to specific teeth may be required in order to
accomplish certain tooth movements.
• Invisalign Assist, an internet access and communication services to the clinician. It
has the benefit of helping treatment stay on track. About every eighteen weeks, the
practitioner has the opportunity to send Align a new set of impressions to verify that the
case is proceeding as expected via superimpositions of the patient’s current impressions
over the original approved treatment plan stage, verifying that the teeth are tracking with
the aligners as planned. If necessary, adjustments are made to the next stage of the
treatment and a new set of aligners are sent to the doctor.