Dentaltown January 2017 - 64

Fig. 1

Fig. 2

Fig. 5

Fig. 6

The importance of impressions
Impressions are an especially critical component of clear
aligner treatment. Align Technologies, the maker of Invisalign
clear aligners, is very selective about the impressions used for cases;
if one is slightly distorted or doesn't capture the entire tooth, the
company will reject it. The extra time and expense associated with
taking additional impressions can frustrate dentists and patients
alike, so my team strives to ensure that the impressions we take are
as accurate as possible the first time around.
The accuracy of impressions can also affect the final case results.
If one doesn't fit perfectly at the beginning of a clear aligner case,
the aligners could be off through the entire process; consequently,
the teeth won't move the way you want them, which alters every
step of the procedure from beginning to end. The importance of
getting the best impression possible can't be overstated: It's a vital
initial step and provides huge value when any kind of restorative
work is being done.

The options with impressions
With traditional impressions, different materials offer varying
benefits-faster setting time, improved flowability, ease of use, and
so on. I recommend looking for the option that, when all is said and
done, provides the greatest accuracy. In this case study I used my
"go-to," Imprint 4 Penta Putty VPS Impression Material from 3M.
Imprint 4 Penta Putty has a fast setting time-2½ minutes-and
is a stiffer substance with higher consistency, which I find easier to
use and more comfortable for patients. When I've used more-viscous
products in the past, they've spread out of the tray and spilled over
into the patient's mouth; for full arch impressions, I want something
that'll be easier for me to handle and more tolerable for the patient.
I combine the putty with Imprint 4 Light VPS Impression Material,

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JANUARY 2017 // dentaltown.com

a wash from 3M that spreads minimally against the putty, but not
out of the tray.
An automatic mixing unit helps eliminate air bubbles and user
error when mixing the product and dispensing it onto the tray. Some
putty materials required a two-step process that included me or my
staff molding balls of putty into a workable substance, which not
only was time-consuming but opened the door for contamination
and inaccuracies in the mixing process. With the Pentamix 3 from
3M handling our mixing, we get a void-free and reliable material
consistence each time.

The struggle with impressions
Many clear-aligner patients are undergoing treatment to straighten
crowded and crooked teeth, which can make obtaining an accurate
initial impression more challenging. In this case study, the patient's
initial visit required several impression retakes because the crowding
of his teeth was difficult to capture. Impressions taken during his
refinement visit, documented below, were easier to capture because
his teeth had straightened out over the time between visits.
Again, using the right impression material can make the process
simpler. Selecting a product with the right levels of rigidity and
flowability will help practitioners obtain an accurate impression
more quickly and efficiently.

Case study and clinical considerations for success
This 40-year-old patient was undergoing clear aligner treatment
to combat severe upper and lower tooth crowding. One tooth wasn't
tracking correctly during treatment, which required new impressions
at his refinement appointment to produce different aligners.
I selected a tray that would fit the patient's mouth (Fig. 1), then
filled it with Imprint 4 Penta Putty (Fig. 2). Once the putty was
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