hello welcome back to another episode of chair sight live I'm dr. Justin Chi
clinical research associate and a member of the team of practicing dentists here
at Gladwell Laboratories for this case I'll show you what I did for a patient that had
post-operative sensitivity for over a year with an Emacs crown that was placed on tooth
number 30 I'll show you how I remove the old crown and then go through the proper bonding
sequence on an obsidian CAD crown to help avoid this situation in the future let's take a look
here our patient presents with a Emacs full-coverage crown on tooth number 30 and
you can see the buccal surface is somewhat under contoured but that's not really the reason why
we are going to replace this the patient states that for over a year since the restoration was
seated she could not chew on the right side of her mouth because of the sensitivity and pain that she
experienced each time she bit down right on it and this is actually quite a common occurrence
that I've heard of from situations where a glass ceramic restoration is bonded in especially so
to remove this Emacs restoration which can certainly be difficult when it's bonded in
place I make depth cuts along the buccal surface and occlusal and then all the way around to the
lingual ensuring that I carefully prep down to the original preparation and also make a cross from
mesial to distal connecting all of these grooves so I use a combination of these ER cater diamond
bur and also the razor carbide burr to assist with making cuts on each surface of the restoration and
then with a crown removal tool with a twisting action to remove these sections sometimes that
final piece may need to be prepped off if it's really bonded on well once the old restoration is
removed I will begin evaluating the prep and see what areas can be improved upon with all ceramic
restorations the preparations ideally should have a one and a half to two millimeter occlusal
reduction and about one millimeter axially with all rounded internal angles that's really key
with these all ceramic materials to ensure that we have a restoration that's well adapted to the
prep once the preparation is set I'll sometimes use a probe or an explorer to run it along the
shoulder of the preparation just to ensure that the surfaces are nice and smooth we also want the
transition from the cervical wall to the axial wall of the prep to be rounded to so we want a
rounded shoulder or heavy chamfer with these all ceramic restorations because again a lot of these
new materials are either milled out and even and when they're pressed they much rather adapt to a
rounded preparation now that the prep is set I place two retraction cores the first one is a
triple zero and followed by a larger second chord size number two and that will help displace the
tissue away from the preparation laterally once the cord is seated I just roll over some of the
other sharp angles that I see and when everything is set I'll place a copper cap the copper cap is
placed to aid with hemostasis and also to provide additional pressure apical e on to the retraction
cord to allow some more effectiveness in its placement once the cord is removed you can see
the separation of the heart and soft tissue and that's what we want to achieve a good impression
for this tooth and really for any tooth we want to not only have a nice preparation but unless
we separate the soft tissue from the tooth we won't be able to accurately fabricate a good
fitting restoration along that marginal finish line so for this case I did scan this in with a
digital impression system designed it chairside and used the TS 150 milling system to mill out
an obsidian CAD lithium silicate restoration the process in the milling cycle took about
12 minutes and the lithium silicate CAD material does require a crystallization cycle of about 20
minutes so I did take advantage of that required cycle to apply some additional staining glaze to
enhance the aesthetics of the restoration once the restoration is crystallized and stained
and glazed I go ahead and test fit it I tried into the patient's mouth and the first thing we
want to evaluate will be the proximal contacts so I'll use some floss to verify that the contact is
where we want that to be and knowing where the contacts were set knowing that they're not too
heavy then we can evaluate the marginal integrity the marginal adaptational this crown to the prep
we want to ensure that the margins are sealed and also that they're flush whenever the transition
from the prep to the restoration is checked we want to verify that that's as smooth as possible
if there's any sort of overhang or over contour that can certainly affect the gingival health and
lead to inflammation for the restoration itself we do have to surface treat it with hydrofluoric
acid especially if you do mill this chair aside when it comes to bonding of these restorations
a lot of times we can desiccate the tooth by over drying the preparation and that's what we want to
avoid so to help avoid desiccating the tooth I will apply an additional desensitizer prior to
delivering this restoration and there are several different desensitizes in the market in this case
I'm using glue ma and most of them have a combination of glutaraldehyde and Hema which
is hydroxy ethyl methacrylate and the combination of the two really helps to rehydrate the tooth to
re-wet it but also a big key with the combination of glutaraldehyde and Hema is they will include
the dentinal tubules and help slow down or prevent the flow of fluids within the tooth and also again
the big part is rehydrating the preparation so I apply a small drop of this desensitizer to the
preparation and while you do this you also want to ensure that you avoid getting this solution
onto the soft tissue because it can cause some irritation to the gingiva I allow the desensitize
ER agent to set on the prep for about a minute a minute to two minutes and once it's set I don't
rinse it off I go ahead and apply the cement into the restoration and then go ahead and seat it and
that's really key to help avoid these post-op sensitivity situations in this case I use three
ends relaxed unison and allow that to enter a gel state and then I'll proceed with the removal of
the cement removing the excess on the buccal and lingual and then with a floss that has a knot in
it to help ensure that the interproximal cement is removed effectively once the restorations seated
we can see that with a chair aside CAD lithium silicate restoration we can help restore the
patient's form and function and also have excellent aesthetics with this as well and
here I just used some gym stock to help verify that the occlusal contacts are ideally where we
want them to be so here is our restoration once it's in place and I'm happy to report
that this patient immediately after the delivery of this new restoration did not experience any
post-operative sensitivity she was so happy that she was able to continue chewing on the right side
an area that she avoided for several months so to help avoid post-operative sensitivity
with these all ceramic restorations it's not so much the material that you decide to use it's
all about the bonding protocol and ensuring that we avoid desiccation of the tooth to ensure that
our patients are comfortable I hope you enjoyed this case presentation on behalf of everyone here
at the lab thanks for watching chairside live and we'll see you back here next time
you