Stephanie returned for her first monitoring visit. Her current set of aligners, stage 3, fit perfectly. I should first report that there was a problem to solve during the scheduled first 3 aligners. Stephanie called us while on her vacation to report that she had “lost” aligners #2. Since the aligner #2, two week activation wear time was almost completed, we instructed Stephanie to move to aligners #3. In most cases, this will work just fine especially when the aligner wear is almost complete for the “lost” stage.

It is best to have the patient return to the office for an evaluation of the fit of the next aligner to ensure the case stays on track. There are several other possible solutions if a patient loses an aligner. I will have the patient simply wear the last prior stage and return to the office as soon as possible. If it seems best for movement sequencing, we will order a replacement aligner from Align and use the prior stage good fitting aligner to hold the teeth in place until the replacement arrives. To insure a good fit it seems to help to have the patient wear the “new” aligner for a longer activation time of 3-4 weeks to help reduce the chance of movement lag. In Stephanie’s case, during her monitoring visit, aligner #3 appeared to be an excellent fit.

IPP was scheduled for several mandibular anterior areas. I like to perform IPR in a sequential and incremental fashion. The IPR prescription supplied by Align is a very basic guide to outline the interproximal reduction. It is first important to execute some IPR at the indicated contact at the earliest stage indicated. The reason for this is that planned tooth movements assume that the tooth is “free” to move within the aligner. Only when the contact has been reduced can the tooth move properly. The second objective is to remove something less than the full amount of IPR scripted.

For example, in Stephanie’s case 0.3mm of IPR is seen in the prescription form for the lower anterior contacts (#24-25 contact at stage 1, #25-26 contact at stage 2 and #27-28 contact at stage 2). Let’s see how the IPR was actually performed. I executed .15mm of IPR at these three contacts at the time of delivery. During the first monitoring visit, we checked these contacts with dental floss and determined that the contacts were not tight, and in fact there was slight space at these contacts, therefore I did not perform additional IPR at these mandibular anterior proximal contacts. Additional IPR will not be performed again until floss tells me that the contact is tight indicating tooth movement to close the contact.

There are 3 additional sites indicated for IPR (#26-27, #23-24, #22-23). The prescription form called for .3mm at each these sites. Again using the sequential and incremental method of IPR, I executed .15mm leaving another .15mm in reserve. In general, I will perform IPR leaving at least .1mm in reserve.

I have used the slow speed disc method of interproximal reduction with great success for many years. The slow speed disc makes a very quick, smooth reduction with little patient objection. The thickness of the disc can be used as an easy gauge to quantify the actual proximal reduction. There are several different disc thicknesses that are useful. I use the perforated .18mm disc (Brasseler 934 size #180 or #220), a thin solid disc that cuts on both sides for a .15mm thickness reduction, and also of value are the solid discs that cut either “inside” or “outside” and have the diamond coating on only one side. The single side disc is the thinnest available and they are .10mm in thickness.

If you will look at the close-up photos, you will see that I use a good finger rest, have awareness of the rotation direction to protect tissue, and most important maintain the disc parallel to the long axis of the tooth to avoid “ditching.”

After performing the IPR always check with floss to ensure that you have not left a ledge. It is important not leave a ledge as the proximal teeth may still touch and therefore not allow the desired movements within the aligner.

Stephanie’s IPR was performed successfully in a sequential (checking at each monitoring interval) and incremental (removing segments rather than the entire amount). I will continue to follow the IPR process for Stephanie in subsequent blogs.