Invisalign – Understanding Unintended Consequences

In January 2013, Invisalign, a popular clear tray aligner treatment system, introduced its next generation product material named “Smart Track”, a more flexible, more consistent force range and better fitting tray. Other improvements to the trays improve bite opening, bite closing, proper “pitch” of upper incisors and built in hooks for elastic wear.  Improvements in the design of tooth attachments (larger, wider and more of them) bonded to the teeth for the tray to push against increase control of specific teeth. Many patients may be surprised to learn that the larger multiple attachments bonded to the teeth somewhat like the clear brackets of conventional orthodontic techniques are necessary for tooth movement, but it is because smooth rounded tooth surfaces do not give the plastic a purchase point for a controlled move. The added attachments make the tray a little more difficult to place and remove, but the more flexible tray makes up the difference.

Invisalign aligners & tray

There is no question that Invisalign has revolutionized orthodontic treatment and provided a desirable feature for many prospective patients, but the revolution is a two edged sword. Like all health care treatment modalities there are advantages and disadvantages, pros and cons that need to be understood before deciding what is best for your situation.  In my humble (because I am a seasoned practitioner) opinion, I believe that the specialists in orthodontics are the “go to” folks for consults. There is a reason why three additional years of training beyond dental school are needed to be certified as an orthodontist – it is a complex biomechanical field quite different from any other field of dentistry. The revolution in orthodontics caused by Invisalign and other clear tray aligner systems is that any licensed dentists can offer orthodontic treatment without the background knowledge of the genetics, biology and physics related to bone and teeth so their results with aligners can be disappointing when compared with what conventional braces could deliver by the hands of an orthodontist.


In fairness, results can be exceptional with aligners by experienced clinicians and final results should be equal with any technique so that there is no ethical dilemma about a poor choice for one vs. the other. Every dentist has seen poor results from orthodontists and it is natural to think you could do better so why not take advantage of a computerized “cook book” method of straightening teeth. However there is a highly significant difference, the orthodontist knows why the result was poor and knows that there is no “cook book” method for excellence. The dentist doing orthodontist’s treatment will soon learn that some of his/her results are also in the poor result category, but will not know what corrections could have been made to avoid the unintended consequences that always accompany human engineering. Orthodontic treatment is best left to those who have dedicated their lives to this challenging calling and who are repeatedly confronted by the problems of making teeth obey force systems without side effects. At the very least, you may want realistic advice.


There is the art and science coupled with patient compliance and motivation that makes beautiful smiles not the appliance or technique. I am pleased and proud of patients that achieve the best result possible regardless of preferring plastic, porcelain, silver or gold.


John B. Harrison DDS, MSc

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