hello everyone and welcome into this episode of chairside life I'm your host Megan strong
in today's episode duct achieves talking about technological advances in chairside milling
we'll take a look at a case example of what cad/cam technology can do for your practice
and your patients then we're bringing back an old segment I love called viewer mail dr. bys
answering some great questions regarding implants and occlusion but first dr. Chi's
exploring a case with failing P FM's on number 18 and 19 he is using a completely digital CAD
cam workflow imagine being able to deliver a crown an hour after preparation your patients
would love you and your practice could rapidly grow let's see how he does it take it away dr. Qi
for this case we have existing porcelain fused to metal restorations on tooth number 18 and 19
and as you can see the buccal area of 18 the feldspathic porcelain has chipped away near
the margin so first things first we are going to remove the existing crowns here I'm using
a 557 carbide burr once the crowns are removed I am clearing out the interproximal areas and
everyone has their own preference when it comes to preparation I just prefer to get the occlusal
reduction taken care of first and then moving on to the axial walls here I'm using a coarse
football to reduce the occlusal surface we are using an all ceramic restoration for this case
so ideal reduction occlusal ii is one and a half to two millimeters and i do use a prep check guide
that shows me what areas need to be reduced even further even though P FM's were placed previously
there was still a lack of reduction so I do most of my gross reduction with a coarse round
ended tapered diamond and once I have most of the reduction occlusal II and actually actually about
one millimeter of reduction and then once the overall gross reduction is completed I will refine
the preparation with a fine rounded a tapered diamond and here sometimes I do like to take
a composite rubber wheel to help roll over the sharp angles we do want rounded internal angles
whenever we prescribe all ceramic restorations and especially in this case when you're milling
restorations the rounder you can make those internal angles that the easier it will be
for the mil-to-mil these restorations so here are the final preparations enough reduction occlusal
II and axially and then once that is taken care of a very important step that should never be
overlooked is gingival retraction here I'm using a double core technique the first layer is a
then our double zero and that will help displace the gingiva apical e and a second layer of cord
is applied right on top of that to help displace the tissue laterally we need to create some form
of separation not just for digital dentistry but in dentistry in general if you're doing it
conventionally it's extremely important and even more so whenever you are scanning chairside and
milling these restorations in your office because again now you are responsible for finding those
margins so we are going to utilize the 3m true definition intraoral scanner and I will apply a
very light mist of the contrast agent and it's just a little bit you don't want to completely
cover the areas you want to scan you still want those areas exposed but all this will do is help
the 3d in motion technology that the 3m true def uses to capture these areas so I start off with
the preparation scans I start off right over to number 18 I get the occlusal areas and I begin my
rotations to the buccal and to the lingual and as you can see the areas are filled in in white any
areas that are missing you will see those appear in a in a dark area with some pink around that and
that will indicate whether or not you're missing that information and you can just easily go right
back over and sweep over it the system captures and acquires the information very very easily
once 18 is completed I begin moving slowly toward the mesial and ensure that I capture everything
buccal lingual occlusal on tooth number 19 and then I began move my way even more mesial to
capture a couple teeth toward mesial neighbors of 18 and 19 and that will help with the design
and also matching this quadrant to the opposing scans which will merge together with our buccal
bite when scanning the adjacent teeth it's very important to also include the contact point of
the adjacent teeth so in this situation the distal surface of tooth number 20 you want to make sure
that that area is acquired as well and then I just capture the opposing scans the entire upper left
quadrant the occlusal surfaces lingual surfaces the functional areas and the buccal surface which
is important for the third set of scans the buccal bite where the patient bites down all the way and
it's also helpful to get the gingival margins for those two previous scans the preparation and the
opposing to merge those together once the data is captured the three intrude F then sends the model
scans to the iOS fast design software and the first step of the process is to set up the case
indicating the type of restoration this these are going to be full coverage crowns then the
type of material we are going to use obsidian CAD the shade is selected which is c3 and then
the next part of the process is to determine the occlusive direction the occlusal direction just
helps the software position the design proposal is properly over the preps then it's time to mark
the margins and just going back to property Sheree traction that's why it's so critical
because now it's up to you or if you delegate to your assistant which is also very very great to
use use while you're using CAD cam and have them mark the margins and work the design because the
software is very intuitive and easy to use so once the tissue retraction is done properly you
can see the margins very clearly when it comes time to market after the margins are placed we
will indicate the buckle directions the software is not really sure which direction is the buckles
so you just help guide that with these arrows and that is just an additional step like the
occlusal direction to aid the software and help guide the position of these design proposals so
here I am manipulating a little bit the proposals the initial proposals and establishing the curve
of speed the curve of Wilson having these lower molars tilted slight toward the lingual and that
just helps to position it properly within the arch once the position is set correctly in the
design portion I typically want to ensure that the functional position is set properly the buccal and
lingual position of these molars are set where the buccal cusp are within good function and the
central fossa of the upper molars of 14 and 15 once the position functionally is set correctly
then I usually will make some minor aesthetic changes the dental technician inside of me wants
to make lots of changes making broader contacts moving costs around it's really not necessary but
I'm just a little bit nit picky when it comes to the aesthetics of these restorations but really
the software does place very very good proposals initially without really any any work needed to
enhance that once I'm satisfied with the designs I will send this off to the TS 150 so each of these
restorations take about 15 minutes to mill and during that time you could actually either work
on another patient or a great thing is to work on any direct restorations that need to be performed
on the patient and with the lithium silicon material you can see it comes out a little bit
in a purplish color it's just a good reminder that you do need to put these in the porcelain furnace
for about a 20 minute cycle and it takes it up to about 810 degrees centigrade for 10 minutes
and during that process it crystallizes and transforms the material into its final hardened
state but here I do try in the restorations prior to putting them in the porcelain furnace for its
crystallization cycle because at this stage I want to adjust the context to how I like them
I verify that the occlusion is where I want it and if there's any adjustments that need to be
made it's much easier to do when it's in this pre crystallized state so I do enhance the aesthetics
I do take advantage of the required porcelain oven cycle and add a few stains to the occlusal
surface and the axial surfaces we were able to deliver these restorations for this patient
within a single appointment replacing failing P FM's on eighteen and nineteen with I think very
beautiful results for any type of Dentistry chair side or traditional so one of the great benefits
of having a chair side system is to deliver and be able to deliver a beautiful result within the
same appointment back to you Meghan thank you for that dr. Qi now it's time for me to take to the
newsdesk we have some viewer mail questions for dr. bye come on let's go for this week's viewer
mail we got a question in on YouTube from a doctor with the YouTube handle armistice and he writes
great videos thank you but why did you leave the implanted tooth out of occlusion on episode
167 of chairside life Meghan that's a very good question and I want to address all the doctors
out there a lot of us already know that there is a major difference between natural teeth and
implants in terms of the way that the implant or natural tooth comes in contact with the underlying
bone so for natural teeth there is periodontal ligament that's surrounding it and it goes all
the way down into the socket into the alveolar process and that is called a gum BOCES which
is a joint essentially between the natural tooth and albula process for an implant what we have is
a solid foundation saw the connection between the implant and the bone and that connection
does not move and we call it a synarthrosis which is sometimes a misnomer and it should really be
called an ankylosis so based on that foundation usually when we restore single posterior teeth
which is what this question was was addressing what we like to do is keep it out of occlusion
by just a little bit so what I usually use is one layer of shim stock and when I check the occlusion
I want to make sure that that is out of occlusion now what gets really complicated with the clusion
and implant dentistry is when you have multiple implants and different scenarios so for example
if you have a single tooth and it's surrounded by many teeth in the arch what we can do is leave
that out of occlusion slightly now let's say we have multiple teeth for example a through Yona
bridge that's being held by two implants what does the clinician have to do and usually with
my experience I have found that when I deliver this restoration the patient will tell me that
they can feel it if it's an occlusion so similar to delivering a regular three under bridge what
I usually do is I place the restoration and I take it out of occlusion slightly there was a follow-up
question Megan with was the armistice on YouTube right so you had answered his question on YouTube
in the comment section and he had replied and said yes I completely agree but I've noticed that the
more aware the less stressful it gets for the bone surrounding an implant itself so for example if
a patient is scheduled for life long every six month checkups but it leaves a country or can't
make the appointment then the implant opposing tooth relation may get tighter and tighter with
zirconia because of less wear so with that being said I think it might be more protective to use
veneered porcelain instead of zirconia thank you for all of your responses responses much
respect for you that's nice yeah it is nice Megan and again I just goes back to implant dentistry
and occlusion being multifactorial in terms of the long term success of the restoration one
of those factors is the occlusal plane and and actually that the buccal lingual width
of the tooth and the type of loading that we can have on top of the implant so usually when we're
loading an implant restoration what we want to do is keep the occlusal table very narrow on the
restoration and that way we can have the forces being compressive and going through the long
axis of the implant now the type of restoration that's also an important question and obviously
I've been placing a lot of Brookes restorations on top of my employ and the reason I do that
is because of studies like the ones coming out of Gordon Christensen and relic Roche instance
group that have shown a favorable response of zirconia versus natural tooth structure
or opposing natural tooth structure so I've felt very comfortable with goozle scheme and I've been
able to restore the cases that way another factor that comes into play Megan and in the audience is
over time there is super eruption of the opposing tooth and that's a major decision and when do we
adjust the tooth and do we bring the patient back once every six months now I want to cite dr. Karl
mich and he had mentioned in several papers that there is something called progressive occlusive
rules of loading so at the beginning if you're loading the implant you might have some forces
that cause there to be cervical bone loss around the implant over time it's okay to progressively
load the implant more and more so as the opposing tooth is erupting it might actually be favorable
in terms of keeping the bone around the implant great well thank you so much for those responses
and Thank You armistice for your questions and if you have any questions you can either
comment on one of the youtube episodes or you can write to us at chairside live at Gladwell dental
com well that about wraps it up for this episode of chairside live on behalf of everyone here at
Gladwell laboratories we thank you for watching and I'll meet you right back here next time
you