Tooth movement animations can be a fantastic tool for both clinicians and patients, but we don't want to kid ourselves or mislead our patients as to what it shows.
First and foremost, the tooth movement animation provides clinicians with an opportunity to double check that the aligner sequence is starting from the correct position! We ask for photos and impressions or scans to help with this verification on our side, but some malocclusions where a patient may displace can be tricky and it is always advisable to verify the starting position is accurate. If treatment is not starting from the right place then the planned tooth movements will not be appropriate and there'll be some tweaking required before giving the go ahead to manufacture the aligners.
There are two questions that are the first big temptations when looking at the animation - what does the "end result" look like, and how many aligners will it take to get there?
Wait a second - "end result"?! Why are there quotation marks there?! Well, the appearance of the teeth at the final aligner stage of the animation is unfortunately not a guaranteed end position. The way that the software systems of aligner plans work is essentially to represent the forces exerted on the teeth at each aligner stage, and this is true of all aligner companies' animations. The implications of this are that the animation can give you a reasonable indication of where the teeth are being pushed, but particularly difficult tooth movements may fall short of this representation and require a refinement phase, or in fact the animation may appear to "over-do" the forces in order to get the best results.
This is why it’s important to reiterate the potential need for refinement when reviewing treatment simulations as the teeth can be stubborn and in most instances may not track 100% to the animated simulation. Understanding challenging tooth movements and over-correction in aligner prescriptions can open new avenues to more efficient treatment plans.Whilst refinements can be a useful way to get finishing just right, additional impressions/scans and manufacturing time will elongate treatment and it's worth every effort to reduce the likelihood of this. If you plan for over-correction from the outset in your prescription then you tip the balance further in your favour.
An example of this would be in a deep bite case, where the appearance in the final aligner stage may be that of an open bite - this is because this challenging movement is not going to be fully delivered and so in reality the overbite should finish in just the right range.
Regarding the number of aligner stages, patients are understandably keen to know how long their treatment will take, and of course clinicians will also want to know the timelines of the orthodontic phase of a patient's treatment. In light of the above, we suggest looking at the numbers of aligners and examining the forces on the teeth at each stage. Make sure that these make sense to you and fit in with your overall treatment aims. An example might be extrusive forces on upper incisors (moving them in an incisal direction) - the animation doesn't show the lip or smile line, so refer to your photos and ensure that the extrusive movements will have the right effect on the incisal show at rest and on smiling.
Another area where the animation risks misleading is in the use of elastics.
The timing and period of elastic wear in a case may vary, but the changes they incur in the bite is always going to be gradual. Rather than guessing as to when and how much improvement in the bite will take place, the animation simply adds the bite correction in at the end. This is why you may see a sudden jump in the lower arch position at the final aligner stage in the animation. Keep this in mind when reviewing your patients, if they are using elastics then do not compare the bite to the equivalent aligner stage in the animation where gradual bite correction isn’t shown.
This is the interesting part of orthodontics where you can almost look under the hood and see what's happening and why! Truly understanding how your aligners are working should give you more confidence with your treatment and also tip you off as to some of the challenging tooth movements that need close monitoring to ensure everything stays on track. This confidence can only help you when showing the animation to patients as you've banished the mystery of what's really happening throughout treatment.