and i admit i'm an under prepper you know i i often tell the story of how i belong to a
12-step group called under preppers anonymous we meet every thursday morning at a local church
and share coffee and donuts and talk about our struggle and any slips we've had in under reducing
that week we've had 30 years of a pretty good thing in dentistry and i think it's time that
we have to step up to the plate and kind of do our job and i think this picture on the screen
kind of illustrates this this is a screen shot of a dental technician here at the laboratory
measuring the reduction that's been done for an emax crown on a molar and sent in by
a dentist and you can see that the laboratory technician can simply click on the prep tooth
and the opposing tooth and when they click on these two spots it tells them that there's 0.85
millimeters of reduction now as you'll see in a minute um it's we need a minimum of one millimeter
of reduction for emax lithium disilicate on a molar and preferably more so with this minimum
of one millimeter it's the lab now has to call the dentist and say hey we don't have enough reduction
on this tooth for an emax restoration now for the last 30 or 40 years it was kind
of a he said she said where the lab technician would say hey i don't think you reduced enough
on this tooth and you'd be all well i was there and i'm pretty sure i reduced enough
and since we write checks and give them to the technicians that would the argument would kind
of end there they wouldn't give us too much pushback but for the first time ever for the
last five years or so dental laboratories have jumped ahead of dentists in terms of technology
and there's way more technology now in the average dental laboratory than there is in the average
dental practice and as a result because of the embrace of cad cam by laboratories it's very easy
for them whether we send a digital impression or a traditional polyvinyl or polyether impression for
them to pour up the stone models scan it and then do exactly what you see here which is click in
between our prep and our opposing tooth and see to the hundredth of a millimeter how much we reduced
there's no more he said she said there's no we've been caught red-handed under reducing
now when you look at the crowns that come in here to the lab at glidewell you'll notice that
75 of the crowns are single unit crowns and another 11 percent are two unit grounds
so we're the largest lab in the country and dentists from all 50 states are sending cases
in here and out of those cases that are coming in 86 of them are one and two unit crowns so i would
say with the way insurance reimbursement is three crowns together you know 18 19 20 or wherever they
may be or 7 through 10 those four that's kind of the sweet spot for crown and bridge where we can
be our most productive have the least amount of remakes so the good news is it would appear the
dentist of america for the most part or at least the ones using glidewell are doing it one in two
units as a time and if we can get really efficient at these and really good at turning out good one
and two unit cases we're gonna have a pretty good career in dentistry and so one of the ways to get
proficient is with loops and um we did not have these in dental school this was an after dental
school modification these are the three loops in one it's a 3x 4x and 5x the downside of these is
they're kind of heavy you know the if you if you don't have a wide broad nose like i do an italian
nose that can support a lot of weight you may not like these loops but i love prepping everything
at 3x i went from 2x with my first set and then to 2.5 on my next set of loops now i'm at 3x for most
of the prep but i love going to 5x for the last 90 seconds to two minutes of the preparation so we
need to make absolutely sure how smooth the margin is it doesn't matter with the rest of the tooth
leave it rough it's micro mechanical retention it's fine but when laboratory technicians got
involved with cad cam and started blowing up dennis margins you can see the chunks out of
the margin and it makes it very hard for them to mark the margin it ends up looking like a richter
scale with a 2.0 earthquake kind of going along the margin and most materials don't like to be in
that kind of zipper shape and so we need to smooth it because we know when the technicians blow up
they're going to see it so these are the loops that i like so for this case we're gonna prep
tooth number nine using this technique uh it's an interesting case because tooth number seven
is an all ceramic crown not a very good one tooth number eight is a natural tooth and 10 and 11 are
splinted pfms so we've got all kinds of things going on here and we tooth number nine is an
endodontically treated tooth with some old failing composites and approximately so we're gonna go
ahead and prep this for a crown so step one of the reverse preparation technique like most other
crown prep techniques is the break to contacts so again i'm just going to use a 56 burr here all
we're trying to do is create some space between the prep tooth and the adjacent tooth so here we
are putting in a double zero cord this is an ultra pack cord from ultranet and i'm just flossing it
into place like it was dental floss and then leaving a little excess on the facial so i
can pack that down uh into that facial sulcus now this cord hasn't been soaked in anything there's
no epinephrine or anything in any of the strands so it's a totally plain cord so here we go i said
we were going to be doing it early and very early on we're prepping and then we put the copper cap
on top have the patient bite down for 10 minutes i come and why 10 minutes because that's how long
it takes me to do a hygiene exam but no 10 minutes in this case is to get all the blood out of there
take it off rinse off whatever styptic material you're using it will look like the patient had
a gingival transplant i mean the gingiva looks so good it will blow you away don't admire it
too long because the blood's coming back from the capillary bed and it's angry that it's been forced
out for the last five minutes so take it off and quickly take that impression but these anatomical
copper caps can be lifesavers in dubious crown and bridge situations especially on posterior teeth
anteriors too but especially on posterior teeth so the reverse preparation technique works fantastic
anytime that you're prepping a crown for the first time on a tooth but what about all those
times where we're taking off an old crown we don't know where we are for years i struggled
with that and what to do and that was solved for me a couple years ago when a company called
contact easy came out with the prep sure crown prep guides that you see on the screen right now
so reduction is very important and considering that every lab owner and technician i've ever
talked to says it's the number one issue that they fight with us dennis we need to step our game up
it's time for 30 or 40 years we got away with eyeballing it and under prepping and uh hoping
they didn't notice or just arguing that with them but they're checking it now digitally every lab is
the gig's up they can see what's going on we got to step up so whether it's getting involved with
you know digital scanning so we can check our reduction that way using the reverse preparation
technique or using those prep sure guides from contact easy make sure you're reducing and
checking enough i really hope you'll you'll get some of those round birds and try doing the margin
that way it's a fantastic way to be able to form that margin and get some depth cutters for your
initial prep so you know where you are i promise you the more attention that you pay to reduction
and getting the right reduction in the right places the better the restorations will look
that come back from your technicians and the more your technicians will love working with you
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with the rise of the monolithic restorations like solid zirconia and lithium disilicate i don't find
much of a use for my two millimeter depth guard anymore i'm using the 0.6 the one and the 1.5
most of the time those are the workhorses and the two and not so much the even the 0.6 the one and
the 1.5 get the most use the two millimeters i'm not using that much because i don't do
bi-layered restorations anymore like porcelain fused and metal porcelain fused as zirconia