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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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