The Truths and Myths of Aligner Therapy

Updated: Jan 6

Download PDF • 1.58MB

The Truths and Myths of Aligner Therapy

Invisalign has been commercially available since 1999, and now some of the key patents that Invisalign had in place have expired. There has now been an influx in the market of numerous other aligner companies and traditional orthodontic companies adding aligner therapy to their range of products. Clear aligner treatment is now in high demand mostly by adult patients but there is an increasing trend for children seeking aligner orthodontic treatment.

It is becoming increasingly more popular due to its advantages over traditional braces of no fixed brackets or arch wires and easier maintenance of oral hygiene. Clear aligner treatment can be an excellent alternative to conventional fixed braces, however, there are some pros and cons to consider, and most importantly to understand the myths and misconceptions of this relatively new orthodontic approach.

Aligners provide the following benefits:

More aesthetically pleasing, especially for adult patients.

Many adult patients now ask and even demand to have clear aligners, as they do not want conventional fixed braces. Most adults don’t like the look of brackets and wires on the teeth. For adult patients this is usually related to social or work-related reasons. Some adults may even consider it too late to get braces, and perceive that clear aligners are the way to proceed for adults, whilst traditional braces are more for children/adolescents.

Reduces dietary restrictions

By not having the brackets and wires with all the precautionary instructions given when getting conventional fixed braces.

Generally, allow the patient to maintain better oral hygiene.

Since the patient removes the aligners for eating, brushing and drinking anything other than water, there is less debris on teeth and teeth are much easier to clean without the obstacle of fixed braces.

Less chairside time is required during an average patient visit.

The typical visit requires assessment of tracking, checking attachments are intact and assessment of IPR requirements. Some visits require longer appointments, such as bonding

of attachments – but these too are much easier than bonding with traditional braces.

Provide fewer emergency appointments There are no broken brackets or wires that have slipped around causing damage and discomfort to the cheek or gums.

However, Aligners have the following limitations:

Aligner patients may have longer treatment times (especially for the inexperienced aligner clinician).

Treatment may take longer due to slower and less predictable tooth movements, and the fact that certain aligner protocols can be clinically ineffective.

Treatment is highly dependent on patient compliance.

The patients need to wear aligners a minimum of 22 hours per day (to be removed only for eating and teeth cleaning ) to achieve any dental changes as per the proposed setup.

The seven general myths of aligner treatment:


The initial setup provided by the aligner company is accurate and can be approved without modification

Unfortunately, this will never happen – I believe you have more chance of winning Tattslotto two weeks in a row!!! There are numerous reasons for this – there can be play and lag with the aligner material and hence the teeth will not track absolutely perfectly as per the digital set up. Even in fixed appliance therapy, we place wires to provide significant tooth over-correction and we still just achieve the desired end result. This is no different with aligner setups where significant over-corrections need to be built into the set up just to achieve an ideal outcome.


I can rely on the technician to perform the set up and click the approve button

Never should we rely on a technician to provide the perfect set up as we need to assess this from a clinical feasibility point of view. Otherwise we are just performing “cartoonodontics”. Hence, we need to understand the predictability of tooth movements such as distalisation, Class II or Class III correction to understand what we can achieve clinically. As Isaac Newton said “For every force there is an equal and opposite force” and hence a knowledge of biomechanics is essential to understand attachment placement and design, based on various tooth movements and the reciprocal effect of these tooth movements on adjacent teeth. Without this knowledge, incorrect placement and design of attachments will cause a lack of seating of the aligner over time and hence reduce or possibly eliminate the efficiency of any tooth movement that was scheduled in the appliance design. In addition, a thorough knowledge of correct staging of treatment is vital. Tooth movement can be restricted by incorrect staging and having constraints in the system that do not allow movement to occur. One of the big issues with any aligner therapy - is if the aligner does not fit properly i.e. does not track well, and then in every subsequent aligner it will be fitting less than the previous one and the lack of movement becomes a significant domino effect. I have never been involved in an aligner case that I have not gone back at least three if not 4, 5 or 6 times to modify the digital set up before approving the aligners for fabrication.

Figure 1a. Linitial photos of patient with Figure 1b. Poor planning resulting in lack

crowding and minimal overbite of extrusion of anterior teeth


All movements are equal

All aligner software utilises specific attachments and velocities for different tooth movements. Having said this, there are situations that require different attachments and different speed of tooth movement to achieve more predictable outcomes. The experienced aligner practitioners have known for some time that teeth which require significant extrusion, significant root tip and even rotating curved teeth such as canine’s have had the challenges and have been unpredictable. We have also seen traditionally a squeezing effect of aligner treatment in the upper anterior region which invariably causes intrusion to the upper lateral incisors-and hence these teeth require attachments routinely to prevent the unwanted intrusion(even though there was no intrusion performed in the digital set up). Many of the movements required – such as rotating crowded teeth, or bodily movement of teeth into extraction sites, or even extrusion of teeth – require spacing to be present to allow full

coverage of the aligner on those teeth and hence correct staging of treatment is paramount to the success of aligner therapy. It’s not appropriate just to look at the initial set up on the final set up. One needs to look at each stage of the process to assess exactly the space requirements and how the individual tooth or teeth will be moving at each stage of aligner treatment.


Only need to do a simple accreditation course to use aligners properly

There have been significant advances in aligner therapy over the last five years – with more predictable approaches to correction of Class II or Class III malocclusions by combining aligner treatment with appliances such as the Carriere Distalising appliance. Also, we are seeing the advent of the hybrid aligner system, where aligners can be combined with fixed braces – the practitioner can choose to start treatment with fixed appliances for a shorter period of time and then perform the fine tuning of alignment or even commence treatment with aligner therapy and then possibly finish the case with fixed appliances.

Nowadays, there are many companies who are offering aligner therapy for dentists and orthodontists. However not all clear aligners are the same. They are different in the aligner material, the type of attachments that can be utilised, their manipulation software, staging of treatment, online portal, support and education, and many other different aspects, and obviously cost as well.

There is further new disruptive technology in the dental industry. Recently, companies such

as Smile Club Direct have started to advertise significantly cheaper treatment costs to patients

by eliminating the majority, if not all doctor visits. Only a scanning appointment or a DIY impression at home is required then shipping all the stages of aligners at once to the patient to use at home, with no supervision of treatment by an experienced practitioner.


Diagnosis is not important because the aligners will move the teeth

Aligner therapy should only be one part of a dentists armamentarium for orthodontic correction – and it is still vital that dentists understand proper orthodontic diagnosis and

treatment planning – and be able to utilise fixed appliances for those cases that are more

appropriately treated with braces – and use aligners for those cases that would be more

appropriately treated with clear aligner therapy.

Remember if you only have a nail – then everything relies on a hammer. I don’t believe

there is any area in dentistry that would rely on one type of therapy to resolve all issues.

This I believe would be mistreatment and mismanagement of our patient to purely rely

on one modality of treatment in orthodontic delivery to our patient.


The amount of IPR and where and when it should be performed is dictated primarily and solely by the aligner company’s digital set up

This is one of the great fallacies in aligner therapy - and in fact the greatest clinical reason for aligner treatment not tracking, is if there is binding occurring between the contact points of various teeth. Unless there is at least 0.5mm of collision between teeth, the aligner algorithms

do not pick up any binding and hence would not prescribe any IPR.

Also, the extent of the IPR that is suggested by an aligner company is dependent on the prescribed movements being 100% achieved. By that I mean, there may be 5mm of expansion

prescribed – but if only 2mm of expansion is actually achieved – that would mean further

binding and further IPR would be required than the prescribed by the aligner company’s digital set up.

Hence, from a clinical aspect every time the patient presents to your practice for an aligner

adjustment visit and for you to provide them with their further aligners – it’s essential that

there are no binding contacts. If any contact point has binding at that time – or anticipated in the future stages/aligners you are about to provide, then removal of this binding and any

anticipated binding is mandatory with IPR - irrespective of what the aligner company states in their digital setup.


Drs expect aligner treatment will require 2-3 case refinements

In the past, practitioners expected treatment would require at least two and usually three case refinements to even obtain a satisfactory result.

Over the last few years, with advances in technology and more importantly advances in knowledge of treatment planning, experience with the correct staging of treatment and a thorough understanding of biomechanics and aligner attachments, we are now finding if all is done correctly at the beginning of treatment, aligner cases can be completed with only one refinement – which would be the equivalent of “case finishing” or “fine tuning” if one was referring to a fixed braces case.

In fact, our Complete Aligner Planning Service (CAPS) which has partnered with the world renowned ClearTPS - have now been involved with over 150,000 aligner cases – and have demonstrated less than a 10% case refinement rate.

Figure 2a. Initial malocclusion, significant Figure 2b. Excellent result achieved in

crowding of anterior teeth 15 months - 45 aligners in total

Figure 3a. Initial presentation with patient Figure 3b. Completed case with 28

with spacing upper anterior teeth aligners and approx. 1 year of treatment

with an excellent result

In summary, to provide efficient and predictable aligner treatment requires the correct plan. The correct plan requires extensive knowledge of aligner biomechanics, the correct staging of movements, the type, position and size of the attachment for various movements, the over corrections required for different objectives and a realistic understanding of movements

that can be achieved. This requires excellent knowledge as a result of loads of training, learning and practical experience.


Dr. Geoffrey Hall

Specialist Orthodontist

Director of the OrthoED institute

Director of CAPS

Download PDF • 1.58MB