All orthodontic appliances have limitations as well as advantages. In this regard, we would like to address some of the shortcomings of Invisalign. The dentist utilizing Invisalign should be aware of its disadvantages as well as its advantages.

First, although the orthodontists/innovators of the Invisalign concept are testing its utility for use in a more varied patient population, it is recommended today for a very small percentage of orthodontic problems. As such, the appliance is advertised for mild orthodontic problems. The notion that may come from this is that these types of cases are "easy."

However, we believe these are truly the more troublesome cases. It could be argued that orthodontic treatment cases that have a relatively severe malocclusion, say an Angle’s Class II¹ with a 10- to 15- millimeter overjet, may be more difficult to treat from an orthodontic-mechanics perspective, but they are less troubling from a patient-satisfaction viewpoint.

For instance, a patient presenting for Invisalign orthodontic treatment for a relatively mild problem might be more prone to expect an ideal and perfect result and finish because his or her case is "mild." A slight deviation from perfection may not be tolerated by this patient. Remember, that is why he or she presented for treatment; that is, treatment of a mild orthodontic problem. The patient is focused on the slightest of detail.

Perhaps the patient with the severe Angle’s Class II¹ malocclusion whose orthodontic treatment does not quite finish ideally (slight overjet remaining, etc.) and even has some relapse, still will be satisfied with the treatment result considering where he or she started from and the obvious improvement.

Also, consider that the Invisalign patient is probably paying a high price for a very minor correction and would be fussier about the result and its stability. What emotional price does the dentist/orthodontist treating the Invisalign patient potentially face with patient complaints and possible retreatments?

The Invisalign system uses many, many aligners to treat relatively minor orthodontic problems. Most, if not all, of the Invisalign cases could be more efficiently and economically treated with partial fixed appliances, Hawley spring-aligners, positioners and so forth.

Furthermore, we have adapted an Essix, clear, plastic removable appliance, which is similar to and the forerunner to Invisalign, for "active" tooth movement. This appliance can be fabricated in-house and correction can be accomplished with one or two appliances.

Both the Invisalign and the Essix-based appliances are rather rigid, plastic-type appliances with little of the flexibility (elasticity/spring) necessary for ideal, efficient tooth movement. This is the reason there are so many appliances (aligners) used in the Invisalign technique. The teeth to be moved are slowly "teased" into position with each successive aligner. These type appliances basically tip teeth, with negligible "bodily" tooth movement.

For the Essix, the appliance is adapted for tooth movement by a prior tooth/model set-up, the addition of attachments, or "divots." For Invisalign, the dentist/orthodontist must, for certain cases, add bonding resin/auxiliaries to the teeth and/or aligner(s).

Finally, there is a compliance issue with the Invisalign appliance because it is removable. The Invisalign patient must faithfully wear the aligner(s), and also clean and care for them. In this regard, some orthodontic patients would consider it a liability rather than an asset to wear a removable appliance vs. a fixed appliance.