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Virtues of VirtualDigital impression-taking systems and electronic data transmission to change the model of dentistry.
By Richard Palmer
ForwarDTrends
12 dentallabproducts August 2008 dlpmagazine.com
Creating dental restorations conven-
tionally has always been a very tactile, hands-on, physically
laborious process for both the dentist and laboratory techni-
cian. From impression-taking to hand-pouring the model to
porcelain buildup, each step in the process requires touching
and examining a physical representation of the case.
Today, with the advent of digital impression-taking sys-
tems, Internet portals, and CAD/CAM technology, some
traditional physical fabrication steps have gone virtual. New
advancements in digital technologies are now available that
could one day eliminate not just the use of physical impres-
sions but in select cases the very models technicians use
every day, creating a new virtual world of dentistry.
First step FirstFor the most part, digital dentistry in the lab currently is
limited to the scanning of a poured model to digitally capture
physical information, which is then used in the virtual design
(CAD) and manufacture (CAM) of restorative substructures,
such as zirconia frameworks, wax patterns for pressing or
casting, all-ceramic full contour crowns, implant bars, and
patient-specific abutments. Impression-taking and model-
prepping procedures include unpleasant, time-consuming,
costly, and hazardous processes that would be eliminated if
the entire process began with digital impressions.
Four digital impression systems are available now for
chairside use: CEREC (Sirona Dental Systems), Lava Chair-
side Oral Scanner C.O.S. (3M ESPE), iTero (Cadent), and E4D
(D4D Technologies). Comprised of a handheld acquisition
unit for capturing tooth prep data (i.e., digital impression)
and a design module, each allows the dentist to instantly see
the three-dimensional digital tooth prep on the computer
monitor in a positive configuration (versus the negative
format of a traditional impression). After reviewing the 3D
prep image, the clinician can adjust the tooth prep, if neces-
sary, capture a new image right then, and send the digital
impression files electronically to a laboratory equipped
with the compatible laboratory component (D4D expects
to introduce a lab component early next year). When the
laboratory receives the data, the two parties can consult in
real-time on the case, make further adjustments as needed,
then proceed with the restorative case design.
Both the D4D and the CEREC systems also allow the
dentist to design and fabricate inlays, onlays and full-contour
single-unit ceramic restorations directly at chairside while
the patient waits in the office. However, until recently, the
use of these acquisition and milling units was limited to
these type of select cases.
“The goal of chairside systems has been to get the patient
in and out very quickly and not have to come back,” said
Lee Culp, CDT. Founder of Mosaic Studio dental laboratory
and the Institute of Oral Art and Design teaching facility
(now part of the Dawson Academy), Culp also has been
instrumental in bringing the D4D system to market (see
“On the cusp” sidebar on page 15). “The system gives the
general dentist an addendum to his workflow where he can
do a single crown or a couple inlays fast and easy.”
With the ability to now use the chairside system for digi-
tally capturing intraoral data and sending case files the labora-
tory, the role of the chairside system is greatly expanded. Dr.
Roger Briggs has used his CEREC 3 chairside unit at Briggs
Family Dentistry in Scottsdale, Ariz., since the upgraded sys-
tem was launched several years ago. “We probably do maybe
//// Digital impressionsForwarDTrends
13August 2008 dentallabproductsdlpmagazine.com
starting oFFWorking with the CEREC Connect system, Cody iverson, G.M. of Iverson
Dental Laboratories, creates a cutting-edge restoration without a model,
going from virtual to reality.
The lab receives the electronic prescription from the doctor with the
digital impression image (Fig. a) and prescription information.
The virtual model is trimmed to replicate a working die and the margin
marked using the automatic margin finder (Fig. B).
From an anatomy library, the technician selects the design of the tooth
to replicate adjacent teeth (Fig. C).
Through virtual grinding, the software adapts the crown to the model,
adjusting contacts and occlusion to specified parameters (Fig. D).
In the final milling preview, the last adjustments and directions for milling
the crown are completed (Fig. e).
The crown is milled out in the “blue” partially crystallized state. (Fig. F),
then fired to finish the crystallization process (Fig. g).
The crown is stained and glazed, prepared for cementation (Fig. H), then
sent to the doctor for seating.
Photos: Cody Iverson, Iverson dental laboratorIes.
1.
2.
3.
4.
5.
6.
7.
Fig. a Fig. B
Fig. C Fig. D
Fig. e Fig. F Fig. HFig. g
options and a much wider range of restor-
ative materials. The broadened capability of
the system also frees Dr. Briggs and his staff
to focus on the practice.
“Prepping and cementing is still the
best use of Dr. Briggs’ time,” said Rick
Durkee, CDT, owner of Lafayette Den-
tal Laboratory in Phoenix, who is on the
receiving end of Dr. Briggs’ CEREC Connect
case transmissions. “I see it as giving him
flexibility,” he added. “With as busy as his
office is, it makes more sense for him to
use the CEREC Connect.”
tHe moDel-less moDelDigital impressions and case transmission
moves technology-driven labs further into
the digital domain by offering the ability to
fabricate full-contour single-unit restora-
tions without a model. Removing the model
entirely from the fabrication process not only
shortens the overall turnaround time, but
also eliminates such negatives as dealing
with the dust associated with model trim-
ming as well as the inconsistencies created
by material shrinkage/expansion. However,
without the model, there is no checking the
fit, contacts, and occlusion until the patient
is back in the chair.
Dr. Briggs compares the experience of
model-less dentistry to walking out on the
Grand Canyon Skywalk, which allows visi-
tors to walk on a clear glass platform that
extends 65 feet out over the edge and 4,000
feet above the floor of the canyon.
However, he said that the fit is usually
comparable, if not better, than a porcelain
crown created on a model, requiring little
adjustment prior to seating and cementing.
The key is getting the initial digital impression,
which requires the same standard learning
curve associated with any new technology.
Durkee commented, “It’s a little out of
the comfort zone not to have a model, but
it’s a work in progress and we’re getting bet-
ter the more we do. It seems to be working
extraordinarily well.”
Iverson Dental Laboratories in Riverside,
Calif., also is registered on the CEREC Con-
nect Web portal (www.cerec-connect.com).
General Manager Cody Iverson said the lab
signed up when the system was first launched
but just received its first digital case in July
(see “Starting off” sidebar on page 13). “It’s
just a matter of getting dentists on board,”
he said.
He attributes some of slow start to den-
tists not thinking outside the box. “They’ve
got the CEREC, and they’re milling inlays and
onlays in-house. Our job as dental techni-
cians is to show them the bigger picture and
enlighten them to the complete benefits,”
said Iverson, referring to milled full crowns
and larger restorations. “They’re not con-
cerned about the fit because of no models.
15 cases a month of single-unit, right-then-
and-there, let’s-get-it-done work,” he said.
But for the more esthetic cases or larger
cases, Dr. Briggs can now digitally capture the
case and through Sirona’s CEREC Connect
Web-based communication system, which
launched in February 2008, send the scan
data to a laboratory for design, milling, and
finishing of a broader range of restorative
ForwarDTrends \\\\ Digital impressions
14 dentallabproducts August 2008 dlpmagazine.com
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The benefits include everything from fit and marginal integ-
rity to less adjustment to cost.”
For now, fabrication of restorations that are entirely
digital until the milling with no models is limited strictly
to full-contour single units, mostly posterior, without any
substructure.
“Anything full contour can be made without a model,”
said Culp. “As soon as you go to a coping, you have to have
to have a model because you have to have contact and
occlusion.”
But that certainly doesn’t limit the number of units that
can be produced. According to Culp, these systems allow
the clinician/technician team to handle cases involving the
restoration of multiple teeth simultaneously. “You can do
an 8-unit case. Scan it all, send it, design it, have it all milled
out, and with the accuracy to go to full contour without a
model,” he said.
Culp adds that with file splitting technology, a design can
include a milled zirconia coping topped with full-contour
pressed anatomy. “You can take the digital information to
make a zirconia coping, and as you sent that data to your
milling center, you would also send data to a processing
center to have a wax full-contour restoration printed at
the same time that would go over the zirconia coping. You
would take the full contour wax pattern, fit it over the zir-
conia coping, and press to it. So, you could get rid of the
models by pressing over a preprinted, computer-designed
wax pattern over a zirconia coping. If everything is done
properly you don’t need a die.”
To get over the mental hump of the model-less zirconia
crown, Culp concedes that dentists and technicians—like
Dr. Briggs and Durkee—need to take a leap of faith over
the canyon’s edge in the precision of digital technology.
“If everybody trusted the systems and trusted CAD/CAM,
we really don’t need models for doing most of what we do
in dentistry, which is single units.”
not tHere yetTo accommodate those who are ready to accept digital den-
tistry but still prefer or need the double-check afforded by
models, each of the digital impression systems either incor-
porates stereolithographic (SLA) or milled resin-polymer
models, or plans to in the future.
“The world is not really ready for model-less dentistry,”
said Culp. “The technology right now in digital is way ahead
of the acceptance curve. Instead of forcing people into what
we feel they should be doing, we’ll let them evolve into what
they want to do.”
By providing the option of models, the manufacturers
allow technicians to set their own comfort level but still keep
the door open into advanced technologies. File splitting
also is an integral part of the 3M ESPE and Cadent model-
based digital systems. After approval of the digital model
design, with margins marked and dies trimmed virtually,
the model data is sent electronically to a central facility for
the fabrication of the physical model while the lab simulta-
neously continues with the design of the restoration. With
the Lava C.O.S. digital model, the digital technician can
design a zirconia framework that can be sent to a Autho-
rized Lava Milling Center for milling or to one of 3M ESPE’s
“selectively open” manufacturing partners. Likewise, the
iTero data can be sent to a CAD/CAM system compatible
with Cadent technology, such as Wieland’s Zeno system.
After both model and structure are completed, they meet
together at the lab bench, and the technician continues
with traditional hands-on methods.
on tHe CUspThe recently launched E4D system allows the dentist to scan, design, mill, and seat metal-
free single-unit restorations in one visit, with future lab designing and milling components
set to expand available options to the practitioner.
The teeth are prepped for the restorations (Fig. a), and the digital impression is
captured using the acquisition unit (Fig. B), guiding the user through the imaging
procedure (Fig. C).
The impression and prescription data are sent electronically to the lab for analysis,
consultation, and approval (Fig. D).
The user can move, rotate, and expand the image on-screen during the design
process (Fig. e).
The single-unit restorations are
milled (Fig. F), stained and glazed,
and baked.
The teeth are prepped for seating
(Fig. g), and the restorations are
cemented into place (Fig. H).
Photos: lee CulP, Cdt, mosaIC studIo
1.
2.
3.
4.
5.
GPs using an in-office digital impression-taking device
4.1%
ForwarDTrends//// Digital impression
15August 2008 dentallabproductsdlpmagazine.com
Fig. C Fig. D
Fig. e Fig. F Fig. HFig. g
Fig. a Fig. B
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FoUr on tHe Floor Though similar in appearance, the digital impression systems currently available for the capture of intraoral surface data are
designed to help streamline production and heighten communication accuracy and expediency between clinician and tech-
nician. The lava Chairside oral scanner C.o.s. from 3M ESPE (www.3MESPE.com/LavaCOS) and Cadent’s itero (www.
cadentitero.com) center around the manufacture of a durable resin polymer model, while the E4D from D4D Technologies
(www.d4dtech.com) and Sirona Dental’s CereC and inlab systems (www.sirona.com) offer model-less dentistry. However,
all four system plan to provide labs with the option of working with CaD/CaM-produced model or model-free.
To reduce turnaround time further and
provide a bit more control over the process,
Cadent is looking into a business plan that would
allow high-volume labs to incorporate an on-site
model-making system at their facility.
Although it now is essentially a model-less
system, Sirona plans to incorporate SLA mod-
els into the CEREC system by February 2009.
According to Norbert Ulmer, Sirona Director
of Laboratory CAD/CAM, “We believe that it is
important to be able to offer physical models
to our customers. At the same time, we also
feel very strongly about the cost and time sav-
ing aspects of model-less dentistry.”
Moving in the other direction, the model-
based Lava C.O.S. system is offering a model-
less option. According to Brian Keenan,
Marketing Manager for the Lava C.O.S., “For
those labs who want to go model-less, 3M
ESPE has new technologies in the pipeline
to make that a reality.”
gearing UpBefore model-less dentistry can grow into
a viable option for labs, dentists need to get
the digital impression acquisition units into
the operatory, which may happen sooner
than later.
When asked in the June 2008 Dental
Products Report Technology survey¹ about
technology purchases, 4.1% of respond-
ing GPs said they currently own a digital
impression-taking device, and 18.4% plan
to purchase the high-tech unit in the next
12 months. That’s a potential of nearly one-
quarter of U.S. practitioners with the ability
to take digital impressions and needing labs
to send the data to.
“We need to have the dentist system
first,” said Culp. “And we need to have enough
out there so when we do go to the labs, they
have a market already developed for them
to talk to.”
In order to talk to as many dentists as pos-
sible, both Lafayette Dental Laboratory and
Iverson Dental Laboratories plan to incor-
porate multiple systems into use. “I want to
position my lab to be able to accept digital
impressions of all types,” said Durkee. lab
references1. The june 2008 Dental Products Report Technology Census survey was e-mailed and direct-mailed to 3,216 GPs in the united States; 444 completed surveys were returned for a response rate of 13.8%
GPs with digital im-pression systems on their “wish lists.”
18.4%
ForwarDTrends \\\\ Digital impressions
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