hello welcome back to another episode of terra sight live i'm dr. justin she in this
episode registered dental assistant will schmidt discusses full-arch PBS impression
techniques more specifically impressions taken by dental assistants for night guards snore
guards Invisalign starts and refinements and any full-arch impression that requires
more detail than an alginate or pentameter impression can provide take it away well
thank you dr. qi i want to focus this episode on a specific technique that i prefer when
taking full-arch diagnostic impressions today's demonstration is going to be performed solely on
unprepared teeth no retraction or temporization is necessary dental assistants perform full arch
impression procedures in cases where Invisalign preparation occlusal guards and snore appliances
require extremely accurate models to proceed my process is similar to a two-step impression but
with a bit of a twist one of the main challenges with two-step impressions is the difficulty in
receiving the tray back into the mouth properly to avoid a step or a double impression the bonding
of multiple layers of material can also be a deterrent let's look at a different approach
to avoid these common failures my armamentarium for today's demonstration starts with Glidewell
directs own capture soft putty this VPS material is packaged with separate base and catalyst jars
and corresponding spoons for the wash I prefer Glidewell direct capture syringe medium body
material with standard six point five millimeter mix tips and then capture hard bite registration
with a larger barreled six point five millimeter mixed tip to withstand the higher hydraulic
pressure of the more rigid material all materials can be extruded with the universal one to one by
two to one mixing gun I am also going to utilize a small single-use disposable plastic sheet that
you can usually already find in your office in the form of a headrest cover or a seat cover and your
plain everyday pair of paper scissors the capture putty Basin catalyst jars are color contrasted to
ensure a homogeneous mix when activated the spoons allow the putty to be removed from
the jars without cross-contamination and easily dispensed always in equal amounts closing the jars
immediately after removing putty further protects the remainder from cross-contamination or from
drying out starting with the thin plastic sheet I cut a square just bigger than each of the trays
that I will use for today's impressions since I used a headrest cover in this demonstration
I simply cut a folded square and then unfold it to cut into two individual pieces finish
each square with a centerline cut approximately 1/3 into the center of each sheet while mixing
capture putty there are a couple things to keep in mind be very aware of what type of gloves you are
wearing during the process gloves with powder or added sense such as mint or bubblegum may
actually [ __ ] the setting of the VPS material or prevent it from completely setting at all need the
material with opposing motions to ensure an even mix and remove any excess that you may find to be
too much roll the putty into a cylindrical shape and place into your precise tray I always like
to start with the easier lower arch to build patient's confidence in the impression taking
process shape the material and then place the pre-cut plastic square over it with the centerline
cut in the open space that the tongue will occupy place the entire formation in the mouth press to
seat as much as possible with hand pressure check and make sure that the lips are out of the way and
then ask the patient to bite with firm pressure on two cotton rolls that are placed bilaterally
at the first molar if done properly you should see the excess material squeeze through the locking
holes built into the tray as shown here once the material stops squeezing out ask your patient to
open and immediately remove the impression tray what we have created here is basically
an immediate chairside custom tray since the material is still viscous use finger pressure
to remove any undercuts and form higher walls or troughs if desired I can now put this impression
to the side to continue to set and carry on with my maxillary impression with a new clean
pair of gloves I once again carry out the steps of mixing the Captur soft buddy and placing it in the
impression tray in this demonstration I'm using a metal tray for the mandible and a plastic tray for
the maxilla during an actual treatment I tried to stay away from swapping trays between metal
and plastic and stay true to one product for the sake of this video demo I want to show that the
process is the same between each choice however if I were looking for the most diagnostic impression
possible my preference would naturally be a metal tray overuse of plastic trays compromise results
with consistent discrepancies due largely to the elastic memory of the tray when impinged
on hard tissues inside the mouth or from firm pressure holding the tray in place once again
placing the maxillary tray in the mouth I asked the patient to bite on two cotton rolls and
quickly remove the tray once the material stops extruding out I make a quick sweep to manipulate
the flow buddy if desired and I can immediately move back to my lower arch tray now the plastic
sheet can be removed and I have a VPS custom tray that is not only set but largely free of
saliva integration one more common challenge with two-step impressions moving on to the wash phase
I choose capture medium body syringe able material I prefer the medium body in this situation because
it is going to make up the bulk of my accurate anatomical impression so a bit less viscosity is
beneficial I make sure to bleed the cartridge when I place a new mixing tip on it get into the habit
of doing this every time an uneven unmixed start leads directly to a failed impression extrude the
wash into the tray while keeping the nicks tip buried in the material to prevent air bubbles
from getting trapped and forming pockets fit the tray back into the mouth and seat into place since
our initial putty phase did not render undercuts or tight areas our worries of double impressions
are an afterthought this chairside custom tray is also preventing excess from using out and into the
patient's throat at this stage hold the tray in place with finger pressure and never by asking
the patient to bite on cotton rolls or anything else our impression comes out clean and without
error so we can move on to the opposing arch the custom tray feature really comes handy during the
maxillary impression to prevent posterior loss of wash material into the patient's throat most
dental assistants will be on their own during these stages of impression taking so the lesson
variables that have to be worried about the better once again a perfect compression on the
first try is a predictable outcome in cases where bite registration is necessary a fast
set registration material such as capture hard bite is an ideal choice the one-minute set time
prevents the patient from tiring and slipping out of occlusion don't forget to always all
bleed cartridges especially when opening a fresh tube this material flows at a nice consistency to
be able to be spread at an unrushed pace while also stacking to accurately register the biked
asking the patient to bite and then to smile at the same time will enable you to have an
appropriate field of view during the setting process and make sure the patient has bitten
correctly even though you practiced this stage with them in advance holding the set material
down with finger pressure helps the patient to open and prevents ripping of the registration be
persistent on developing impression techniques that make the flow of your practice smooth and
your patients happy with the outcome capture putty and VPS bite registration materials are always
available for purchase through Glidewell direct thank you for watching today's demonstration
right back to you dr. Qi thanks for those clever tips wool on behalf of everyone here
at the lab thanks for watching chairside live and we'll see you back here next time
you