Out of Sight, Out of Mind?

Tips and Techniques to improve your success with Invisalign

Article from PCSO Bulletin - Winter 2007

By Victoria Lynskey, DDS
Assistant Clinical Professor,
Division of Orthodontics
University of California, San Francisco

So often in our busy lives we take new technology for granted. If it’s not right in front of our face, it just gets forgotten! The new paperless charting system we bought often goes under-utilized because of lack of staff training; the soft tissue laser is a little dusty from lack of use. And your idea of Invisalign is what you learned at your initial certification or at the last workshop you attended back in 2003. Well, Invisalign has changed since then and like all other technology, requires ongoing continuing education to utilize the new advancements.

We all go to CE courses at the AAO or PCSO to hear the latest and greatest on new gadgets, but Invisalign’s technology has been in our offices for years yet we may not be using it optimally. Perhaps it’s the totally different way of thinking that goes into Invisalign treatment planning, or maybe it’s just "invisible" and therefore out of sight and out of mind. Let’s make a plan to change today.

So how has Invisalign changed?

Let’s start with the new treatment protocols, or what Invisalign calls the Clinical Best Practices Protocol (BPP). These new recommendations, like previous Invisalign protocols, were developed over time by clinicians striving to produce better, more reliable results with Invisalign. It is the culmination of opinions by leading Invisalign doctors, research studies (1-3), and over 500,000 cases in treatment.

There are two main elements to the BPP’s:

• New staging protocol
• New attachment protocol.

The New Staging Protocol

The New Staging Protocol is radically different from what we had previously. In the past it was recommended to do "sequential staging," where complex movements of individual teeth were done separately (i.e. rotation and extrusion), with the more difficult movement often left until the end of treatment. We also used to move specific teeth at specific times, initially thought to enhance anchorage or reduce “collisions.” The biggest drawback to the original protocol was that it was difficult for the clinician to determine and estimate the optimum velocity of tooth movement, resulting in long treatment times and excessive numbers of aligners.


Figure 1

The new protocol recommends simultaneous staging. All teeth are moved together from the initial stage through the final stage, just like in traditional orthodontic treatment. The tooth that needs the most movement therefore dictates the overall number of stages, or aligners, based on the maximum allowable tooth velocity.

Invisalign has found that moving teeth simultaneously reduces the velocity for all other movements, while increasing the predictability without increasing the overall number of aligners. For example: in the past we may have had to make space for anterior crowding by moving posterior teeth first, then moving the anterior teeth. Now all teeth will be moving at the same time, just at different velocities. The questions I had when these protocols were first explained had to do with “collisions.” Collisions occur when there is no space between the teeth, causing them to bind. According to the BPP’s movement is not allowed if the software does not detect space. So does that mean more IPR? No, in fact with the BPP’s expansion and proclination are considered before IPR. In addition, IPR is now only programmed on interproximal contacts. Previous protocols recommended IPR early in the series for severely rotated teeth. Performing IPR on rotated teeth often meant removing enamel from other tooth surfaces (such as the lingual or facial) in order to accomplish the reduction. Now the software incorporates better tooth alignment first via proclination or expansion so that IPR can safely be done on the interproximal surfaces only. Utilizing the new staging editor in ClinCheck 2.5 will make sure simultaneous movements are occurring for all teeth throughout treatment.

The New Attachment Protocol

The New Attachment Protocol allows for attachments to be passive or active. Passive attachments are for aligner retention and anchorage for intrusion. Active attachments are used for rotations of rounded teeth, extrusion and root correction. Currently Align Technology has three types of attachments for commercial use: the ellipsoid, rectangular and the beveled attachment (Fig.1). Ellipsoid attachments are often placed horizontally and are the default for anterior tooth extrusions. They are 1mm in thickness and placed between the cervical and middle third of the tooth.



Figure 2

Vertical rectangular attachments as seen in Figure 2 are the default for rotations of canines and premolars. In addition, these attachments are used for root control on teeth adjacent to extraction spaces. For premolar extraction cases, the default is placement of two rectangular attachments distal to the space and one mesial to the extraction space. Typically these attachments are 1mm thick, 2mm wide and either 3, 4 or 5 mm long. The vertical rectangular attachments are very retentive, so take care when placing multiple attachments in one quadrant. The aligner can become too retentive for patient convenience. An interesting option is the beveled attachment for rotations. Sometimes the rectangular attachments don’t fit perfectly and during rotation can put unintended forces on the tooth, resulting in side effects.

Beveling the attachment can ease the fit and make the attachment "active," causing rotation. Rectangular attachments can also be placed horizontally and are currently the default attachment on first premolars as anchorage during anterior intrusion or torque (Figure 3).





Figure 3

They can be beveled incisally (default) or gingivally. To aid you in determining type and quantity of attachments, utilize the superimposition tool. This tool is a fantastic aid in predicting the feasibility of the entire process.

Utilizing the new protocols requires a little work, but the results will make the Invisalign series more reliable and predictable. First, make sure to change your treatment preferences. The new BPP’s often conflict with old treatment protocols. Second, there are significan’t changes with respect to IPR. Minimizing IPR has been a key goal and with the BPP’s, I believe it is significantly reduced. Should IPR be required, it is best to accomplish this after the first two sets of aligners. This eases the patient into treatment and can be done when attachments are placed at stage 3.

I have found that for any patient requiring IPR, I request a virtual c-chain to tighten contacts at the end of treatment to snug up any open contacts. Again, when performing IPR, make sure to log the exact amount at each appointment.

Align Technology has been quite proactive with respect to offering continuing education and regular updates to their software. This product has many more uses than what we learned during our initial certifications. Just as with any other product, it is our job to keep abreast of new changes, additions and modifications of its use.

In a future article, I can discuss specific tooth movements and how to use the BPP’s to improve their reliability. Until next time, although Invisalign is virtually invisible, let’s not keep it out of sight and out of mind.

1. Tuncay, O. C. (ed.). The Invisalign System. Quintessence, 2006.
2. Paquette, D. and Nocozisis, J. Clinical Reports and Techniques, Tuncay, O. C.(ed.) 2006
3. Wheeler, T., Dolce, C. and Taylor, M. Attachment evaluation for extrusion, rotation and intrusion. Cases and Commentaries in Orthodontic technology; pg.5-6, 2000

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