Dr. Gordon Christensen The Dangers of - Glidewell Dental Labs


Dr. Gordon Christensen The Dangers of - Glidewell Dental Labs


A Publication of Glidewell Laboratories • Volume 6, Issue 1

Dr. Gordon Christensen

The Dangers of “Gray-Market”

and Counterfeit Dental Products

Page 14

Monolithic Versus

Bilayered Restorations

Dr. Gregg Helvey Takes a Closer Look

Page 21

Detecting Computer-

Enhanced Dentistry:

How to Spot Digitally Edited Photos

Page 46

One-on-One Interview

Dr. David Hornbrook Discusses

Esthetics, Lasers and Digital Dentistry

Page 32

Dr. Michael DiTolla’s

Clinical Tips

Page 9


9 Dr. DiTolla’s Clinical Tips

Featured in this issue is the IOS FastScan ® , a new

digital impression system that has been clinically

tested at Glidewell over the past three years. Also

highlighted are Clear-Lock Retainers for Life and

the aveoTSD ® Health Professional Patient Sizing Kit,

both from Glidewell Laboratories. Finally, we have

what may be a way to predictably bond BruxZir ®

restorations: OptiBond XTR.

14 Are You Using “Gray-Market” or

Counterfeit Dental Products?

It’s no secret that dentists love to save money. But, as

Dr. Gordon Christensen discusses, purchasing steeply

discounted dental materials when looking to cut

costs may be a gray area you want to avoid. Learn

the dangers of purchasing gray-market and counterfeit

dental products. Plus, Dr. Christensen explains

how to spot gray-market and counterfeit products

and outlines measures you can take to avoid falling

victim to this illegal, yet lucrative, business.

21 Monolithic Versus Bilayered

Restorations: A Closer Look

Advancements in dental ceramics have forever

changed dentistry. Monolithic restorations, such as

IPS ® e.max and BruxZir, are one such game changer.

Dr. Gregg Helvey compares IPS e.max monolithic

crowns to bilayered PFM restorations and highlights

the characteristics of each.

32 One-on-One with Dr. Michael DiTolla:

Interview of Dr. David Hornbrook

Esthetic dentistry authority Dr. David Hornbrook is

one of my clinical mentors and has been ever since I

took his courses at LVI. I checked in with him to see

which modern-day materials he considers the gold

standard for anterior restorations and to gauge his

thoughts on digital impressions, monolithic restorations

and diode lasers. Does this esthetic dentistry

expert believe in same-day dentistry, with crowns

milled chairside in the dental office? I got the answer.

Contents 1


NEW! Read Chairside on the go using your smartphone.

Thanks to a simpler design, you can now

enjoy your favorite recurring columns from virtually

anywhere. Visit www.chairsidemagazine.com from

your smartphone to see just how easy it is.

46 Detecting Computer-Enhanced


When it comes to dental photography and pictures

of products, patients and medical conditions, many,

if not all, pictures have been edited. Maybe it’s done

to hide a crack or whiten a smile, but how can

you be sure what you are seeing is real? Dr. Ellis

Neiburger and Yehonatan Frandzel discuss the many

ways to detect digital photo enhancement. They

reveal that, despite recent developments in digital

imaging in dentistry, there are telltale signs a photo

has been edited.

53 Periodontal Photo Essay:

Is Closed-Flap Crown Lengthening a

Biologically Sound Procedure?

In this photo essay, Dr. Daniel Melker discusses his

feelings on closed-flap crown lengthening. With the

drop in prices of hard tissue lasers, this procedure will

no doubt become more popular among GPs. Rather

than laying a flap and directly observing the bone

that is being reshaped, closed-flap crown lengthening

relies strictly on feel, hence the controversy.

63 Dr. DiTolla’s Patient Product Review

In the last issue of Chairside magazine, I discussed

how men and flossing don’t belong in the same sentence.

Touching again on this topic, I introduce you

to a unique toothpick by Ultradent called Opalpix .

While Opalpix doesn’t replace the benefits of flossing,

it is my best hope for men who appear to be

allergic to floss.




Jim Glidewell, CDT


Michael DiTolla, DDS, FAGD

Managing Editors

Jim Shuck

Mike Cash, CDT

Creative Director

Rachel Pacillas

Clinical Editor

Michael DiTolla, DDS, FAGD

Senior Copy Editor

Melissa Manna

Copy Editors

Jennifer Holstein, Eldon Thompson

Magazine Coordinator

Teri Arthur

Graphic Designers/Web Designers

Jamie Austin, Deb Evans,

Joel Guerra, Phil Nguyen, Ty Tran

Photographers/Clinical Videographers

Sharon Dowd, Kevin Keithley,

James Kwasniewski, Sterling Wright


Wolfgang Friebauer, MDT

Ad Representative

Teri Arthur


If you have questions, comments or complaints regarding

this issue, we want to hear from you. Please e-mail us at

chairside@glidewelldental.com. Your comments may be

featured in an upcoming issue or on our website:


© 2011 Glidewell Laboratories

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herein shall not do be not used necessarily for advertising state or or reflect product those endorsement of the publisher purposes. and

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Chairside is a registered trademark of Glidewell Laboratories.

Chairside ® Magazine is a registered trademark of Glidewell Laboratories.

Editor’s Letter

I have been hearing about the death of PFMs for the past

15 years. In fact, the PFM department managers here at the

lab always have a good laugh when I show them a dental

journal with an article by a metal-free clinician predicting

the demise of PFMs within the next three to five years.

While a metal-free style of practice can certainly work for

dentists who passionately believe in metal-free dentistry,

the numbers at the lab tell another story: PFMs aren’t dead.

Most dentists are satisfied with PFMs and continue to prescribe

them in large numbers. After all, PFMs are versatile

and can be used for single units, multiple units and even

roundhouse bridges. Those who want to pretty it up can

always cut a facial shoulder for a porcelain margin or use

an esthetic PFM, such as Captek , in the esthetic zone.

PFMs have long been the workhorse restoration, but then

one day something happened … and that something was

BruxZir ® Solid Zirconia. For 10 years I begged R&D for

a cast gold crown in a shade A2. Jim Glidewell was bugging

them to make a full-contour zirconia crown, just to

see what it would look like. BruxZir got both of us off

their backs.

From the day it launched, BruxZir was a niche product. It

was meant to be an esthetic replacement for cast gold and

metal occlusals, but I started using it to replace broken

PFMs (because those patients had already destroyed

that type of restoration). All of a sudden, dentists started

placing BruxZir everywhere, showing preference for

this high-strength, cementable, monolithic, tooth-colored

material, despite it being “more brawn than beauty.”

The popularity of BruxZir continues to grow, with a recent

sales record totaling 7,300 crowns & bridges in one week!

That makes BruxZir the fastest growing product in the

40-year history of Glidewell Laboratories.

So while PFMs are not dead, the PFM department no longer

laughs at these jokes. We can use BruxZir to do virtually

anything that can be done with a PFM, including

roundhouse bridges. These monolithic restorations seem

poised to replace their bilayered brethren; however, the

change may be measured in decades, rather than years.

Yours in quality dentistry,

Dr. Michael C. DiTolla

Editor- in-Chief, Clinical Editor


Editor’s Letter 3

Letters to the Editor

Dear Dr. DiTolla,

I have really enjoyed your articles and

video presentations over the years. They

are very informative and helpful.

I have a question regarding your success

rate with the Milestone Scientific

STA System. I have been using it now for

more than a year, and it seems to be hit or

miss, just like the mandibular block. I love

it when it works, but I find it very annoying

when I have to go back and do a block.

I wonder what you might be doing differently.

I use 4 percent articaine with

1:100,000 EPI and usually deposit the

anesthetic for 15 seconds after I have

reached the PDL (about one-third of a

carpule). I have tried both buccal and

lingual placement, as well as mesial and

distal. Many times it does not even get

to three bars on the graph LED. Any

thoughts you may have as to why this is

happening would be greatly appreciated.

– Jeffrey Olson, DDS

Irving, Texas

Dear Jeffrey,

Thanks for the kind words! I did

have a period of time where my

effectiveness with the STA System

went down, albeit very slowly.

My initial enthusiasm for the unit



slowly waned and then, luckily, the

unit stopped working completely. I

sent it back to Milestone Scientific,

and they sent me a loaner to use in

the interim. It was like magic! I was

getting the PDL alert on every single

tooth! I was in heaven. I realized

that the problem was with my unit.

When my STA System came back I

was reluctant to return the loaner.

I kept it in the office for a week, until

I verified that my old one was working.

My suggestion is that you send

your unit in for some maintenance to

ensure it’s working properly.

I usually start in the buccal furcation

with an extra-short needle, and if I

get the PDL alert there I am usually

good. If there is perio involvement, I

usually go to the ML corner, where it

is the norm to get the PDL alert, and

then I also go to the DL corner. If the

patient is phobic or sensitive, I do all

four corners. Sometimes I have to go

back in with a little more in the PDL,

but I have never had to go back and

give a block. I usually see patients

whose last dentist couldn’t get them

numb with a block, and I’m able to

with the STA System.

Keep me apprised of your experience

because I recommend the

STA System to everyone.

– Mike

Dear Dr. DiTolla,

I recently discovered your Rapid Anesthesia

Technique on YouTube, and I have tried

it a few times. What are some of the postop

complaints, and how do you address

them? Thank you for your help.

– Seada Damiano, DDS

Cicero, N.Y.

Dear Seada,

I don’t get that many side effects now

that I use the STA System to deliver

the Septocaine ® . When I was doing

the Rapid Anesthesia Technique using

a hand syringe, I used too much

pressure, which caused some tearing

of the PDL and resulted in the tooth

being sensitive to percussion or biting

in some cases. The STA System

has eliminated the speed and pressure

issues, so I don’t see that anymore.

Post-op complaints are almost

nonexistent now — nowhere near

where they used to be when I was

routinely giving lower blocks.

– Mike

Dear Mike,

Thank you for your prompt reply. I really

appreciate it. I have tried the technique

(manually) about six times. Yesterday a

patient I had seen about a week ago for

an occlusal on tooth #31 came back and

complained of pain in the gingival area.

The tooth was fine on percussion. Maybe

I used too much pressure or too much

solution. I think this technique is fantastic,

and I will look into the STA System.

Thanks again, and have a great day!

– Seada

Dear Seada,

I’m not an STA System salesman,

but when I started using it my confidence

with the technique really

took off. I had a patient come in last

week who left her dentist of 15 years

because he couldn’t get her lower

molar numb on two consecutive

appointments to finish a crown prep.

I used to dread these types of patients,

but I actually look forward to

them now because I have been able

to anesthetize all of them so far. In

those cases, I inject in the furcation

and the buccal and lingual sulcus,

but it has always worked. You truly

become their hero.

– Mike

Dear Dr. DiTolla,

I wanted to thank you for the excellent

veneer video you made. I learned a lot:

putty-wash index, the Rapid Anesthesia

Technique and fixing alignment before

depth cutting! Those were big, and I feel

like I became a better dentist from watching

your presentation.

One question: When you use a putty-wash

index of the wax-up, do you use lubricant?

I broke a few wax-up teeth (glued them

back easily though) when I took my putty

index. The impression material sucked up

all the moisture from the model and adhered

to certain waxed teeth on the model.

– Ruslan Korobeinik, DDS

White Plains, N.Y.

Dear Ruslan,

I have done that as well, although

once the putty-wash matrix is done,

I really don’t need the wax-up anymore.

Of course, you could always

have the lab make a duplicate stone

model of the wax-up, making it easier

to work with. I hope that helps!

– Mike

Dear Dr. DiTolla,

As usual, I read Chairside magazine cover

to cover as soon as I received it (I can’t say

the same for some of the other periodicals

I receive). In the most recent issue, I was

glad to see that you mentioned Glidewell

Laboratories is a CEREC ® Connect laboratory.

(I don’t think it has been properly

advertised, and Glidewell is very good at

advertising.) This might be a good topic

for a future article.

I wrote an article on the subject that has

not yet been published, and I am attaching

it for your opinion. I hope you find the time

to send me some feedback.

– Carlos Boudet, DDS, DICOI

West Palm Beach, Fla.

Dear Carlos,

Thanks for the kind words. I would

love to review the article you sent.

Our only requirement is that it is accompanied

by outstanding clinical

photography! I look forward to reading


– Mike

Dear Dr. DiTolla,

Congratulations on your latest issue of

Chairside. I very much enjoyed the article

“Simplifying Lab Communication: The

Dental Midline Position, Incisal Cant and

Incisal Horizontal Plane” by Dr. Leendert

Boksman. The article seems uniquely appropriate

when one looks at the front cover

and observes and absolutely beautiful

young lady with her upper midline at least

half a tooth to the left of her facial midline

and her left eye fully 6 mm higher than

her right eye. Literally everyone has some

facial asymmetry, including Dr. Boksman

whose glasses have a pronounced uphill

slant to the left. The point is that our stepbrothers,

the cranial osteopaths, and the

rather few practicing cranial orthodontists

have shown that they are able to produce

dramatic improvement and, occasionally,

correction of these asymmetries. The

others simply say that such asymmetry is

“acceptable” (which it must be if one does

not know or understand how to correct it).

I don’t know if this information would be

of interest to Chairside magazine, as it is

more of an orthodontic concern, but the

article in your magazine was absolutely

fascinating to me, and I intend to order

several Onebite facial plane relators

immediately. Thank you so much!

– Gerald W. Spencer, DDS

Sedalia, Mo.



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Letters to the Editor 5


Michael C. DiTolla, DDS, FAGD

Dr. Michael DiTolla is a graduate of University of the Pacific Arthur A. Dugoni School of Dentistry.

As Director of Clinical Education & Research at Glidewell Laboratories in Newport Beach, Calif.,

he performs clinical testing on new products in conjunction with the company’s R&D Department.

Glidewell dental technicians have the privilege of rotating through Dr. DiTolla’s operatory and

experiencing his commitment to excellence through his prepping and placement of their restorations.

He is a CR evaluator and lectures nationwide on both restorative and cosmetic dentistry. Dr. DiTolla has

several clinical programs available on DVD through Glidewell Laboratories. For more information on

his articles or to receive a free copy of Dr. DiTolla’s clinical presentations, call 888-303-4221 or e-mail


Gordon J. Christensen, DDS, MSD, Ph.D

Dr. Gordon Christensen is a practicing prosthodontist in Provo, Utah. His degrees include DDS,

University of Southern California; MSD, University of Washington; and Ph.D, University of Denver. He

is a Diplomate of the American Board of Prosthodontics; Fellow and Diplomate of the International

Congress of Oral Implantologists; Fellow of the Academy of Osseointegration, American College of

Dentists, International College of Dentists, American College of Prosthodonists and Royal College of

Surgeons of England; Honorary Fellow of the AGD; and Associate Fellow of the AAID.

Drs. Gordon and Rella Christensen are cofounders of the nonprofit Gordon J. Christensen CLINICIANS

REPORT ® (formerly CRA ® Newsletter). Contact Dr. Christensen at 801-226-6569 or info@pccdental.com.

Yehonatan L. Frandzel, FPH

Yehonatan Frandzel is an architect and designer based in Haifa, Israel. He is a graduate of Technion-

Israel Institute of Technology, where he studied in the Faculty of Architecture and Town Planning.

Yehonatan is head of Architectural Visualization, 3-D Modeling and Computer Rendering for

Mochly-Eldar Architects, where he lends his extensive experience with the creation and detection of

virtual imaging. Contact him at kaizer@gmail.com.

Gregg Helvey, DDS, MAGD

Dr. Gregg Helvey graduated from Georgetown University School of Dentistry in 1976. He is part of an

elite group of dentists who are also skilled ceramists. This combination of experience as a dentist and

laboratory technician has aided him in the development of unique restorative and laboratory procedures,

many of which have been published in peer-reviewed journals. Dr. Helvey serves on the editorial

board of Inside Dentistry, Compendium of Continuing Education in Dentistry and Inside Dental

Technology. An AGD Master since 1997, he is an adjunct associate professor at Virginia Commonwealth

University School of Dentistry and teaches in the AEGD residency program emphasizing all-ceramic restorations.

Dr. Helvey continues to lecture nationally and internationally and maintains a private practice

in Middleburg, Va. Contact him at 540-687-5855, www.gregghelveydds.com or phident@gmail.com.



David S. Hornbrook, DDS, FAACD

Dr. David Hornbrook graduated from UCLA School of Dentistry and currently practices in San Diego,

Calif. A leading educator in esthetic dentistry, he has been a guest faculty member of the postgraduate

programs in cosmetic dentistry at Baylor, Tufts, SUNY at Buffalo, UMKC and the UCLA Center of Cosmetic

Dentistry. Dr. Hornbrook has also consulted with numerous manufacturers in product development

and refinement and is on the editorial board of many dental journals. He is a past editor of the Journal

of the American Academy of Cosmetic Dentistry and an accredited member and Fellow of the AACD.

Founder and past director of P.A.C.~live and the Hornbrook Group, Dr. Hornbrook continues to lecture

internationally. Contact him at www.davidhornbrook.com.

Daniel J. Melker, DDS

Dr. Daniel Melker graduated from Boston University School of Graduate Dentistry in 1975 with specialty

training in periodontics. Since then, he has maintained a private practice in periodontics in

Clearwater, Fla. Dr. Melker lectures at the University of Florida periodontic and prosthodontic graduate

programs on the periodontic-restorative relationship. He also presents at UAB, University of Houston,

Baylor University and LSU’s graduate periodontal program. Dr. Melker has published several articles

in national dental magazines, as well as The International Journal of Periodontics & Restorative Dentistry,

and has twice been honored with the Florida Academy of Cosmetic Dentistry Gold Medal. Contact

him at 727-725-0100.

Ellis J. Neiburger, DDS

Dr. Ellis “Skip” Neiburger graduated from University of Illinois at Chicago College of Dentistry in 1968.

He practices general dentistry in Waukegan, Ill. A former vice president of the American Association of

Forensic Dentists, Dr. Neiburger has been the association’s journal editor since 1978. His other experience

includes publisher/editor for Dental Computer Newsletter (the journal that introduced computing

to the dental field) and consultant for Apple Computer Inc. In addition to a background in computer

technology and dentistry, Dr. Neiburger also has practical knowledge of law enforcement and was Lake

County, Ill., deputy coroner for many years. Contact him at 847-244-0292 or eneiburger@comcast.net.

Contributors 7

A toothpick

is the object most often choked on by

Americans. Since 1900, 17,000 people

have died from choking on toothpicks,

including novelist Sherwood Anderson.


The percentage

of metal-based

fixed restorations

prescribed in 1997.

by the



The percentage

of metal-based

fixed restorations

prescribed in 2010.

1 out of 3

of the last

2,000,000 shades

prescribed were

A2 and A3.

8 days

The amount of

time sharks’

teeth last before

being replaced

by the next row.

1 out of 2

dentists in Massachusetts sent

a case to Glidewell in 2010.


BruxZir crown & bridge

units were ordered the week

of Dec. 13, 2010, making it

the fastest-growing product

in lab history.



1 out of 142

of the last

2,000,000 shades


were D4.

Six feet

The recommended

distance to keep

your toothbrush from

your toilet to avoid

airborne particles

from the flush.

Dr. DiTolla’s


PRODUCT........ aveoTSD ® Health Professional

Patient Sizing Kit

SOURCE........... Glidewell Laboratories

Newport Beach, Calif.



One of the most common questions I field from

dentists is: “Does that aveoTSD thing actually work?”

Yes, it does, but I understand why they ask. It is a

simple appliance (especially compared to other antisnoring

appliances) with no moving parts that looks

too good to be true. It anteriorizes the tongue directly

without involving the teeth or jaws, hence there is no

need for straps or hinges.

The aveoTSD Health Professional Patient Sizing

Kit is now available to dentists for helping patients

achieve a perfect fit of the device. The extra-oral

titration rings come in 4 mm and 7 mm thicknesses

to accommodate patients with

longer-than-average tongues. And although

the medium size aveoTSD fits

90 percent of patients, the sizing

kit also contains a small and a

large aveoTSD for patient

sizing. Additionally, the

components can be

placed back into the

blue kit for sterilization



Dr. DiTolla’s Clinical Tips 9

Dr. DiTolla’s


PRODUCT........ OptiBond XTR

SOURCE........... Kerr Corporation

Orange, Calif.



Since the introduction of BruxZir ® Solid Zirconia,

I have been looking for a way to bond these monolithic

restorations into place whether using totaletch,

self-etch or conventional cementation. Zirconia

is notoriously tough to bond to, but OptiBond XTR

provides a solution. It also has helped me reduce

post-op sensitivity. And due to its film thickness of

5 to 10 microns, I am able to light cure OptiBond

XTR prior to placing restorations without worrying

about them seating all the way. I simply apply the

OptiBond XTR Primer to the inside of the BruxZir

restoration, air thin and light cure. To bond to the

tooth, I apply the primer with a scrubbing motion

and then air thin. Then I apply the OptiBond XTR

Adhesive to the tooth, air thin and cure. Finally, I fill

the BruxZir restoration with the cement of my choice,

seat it on the tooth, and I’ve got a virtually unbreakable

crown or bridge with a high-strength bond.

10 www.chairsidemagazine.com

Dr. DiTolla’s


PRODUCT........ Clear-Lock Retainers for Life

SOURCE........... Glidewell Laboratories

Newport Beach, Calif.



I often get asked to make retainers for patients who

don’t want to bother going back to their orthodontic

office five years after their first appliance was made.

Most of the time the patient’s teeth have slightly relapsed,

and while he or she doesn’t care enough to

have more ortho, the patient doesn’t want his or her

teeth to get any worse. Thanks to Invisalign ® , patients

now prefer clear retainers to the old pink acrylic

and wire Hawley retainers many of us grew up with.

Glidewell started making clear retainers for dentists

a few years ago. With the advent of CAD/CAM, the

lab realized we could make multiple sets of retainers.

This is especially practical when the patient loses or

damages his or her retainer, which always happens.

The lab now offers Clear-Lock Retainers for Life, a

service in which we send you either three single-arch

retainers (three uppers or three lowers) or one set of

three upper and three lower retainers to give to the

patient. When all the retainers are lost or damaged,

contact us and we will send you three more from our

digitally stored data. It’s a great service that even your

orthodontist doesn’t provide!

Dr. DiTolla’s Clinical Tips11

Dr. DiTolla’s


PRODUCT........ IOS FastScan ®

SOURCE........... IOS Technologies Inc.

San Diego, Calif.



I will readily admit that digital impressions are the

future of dentistry. But as of today, the ROI of digital

systems leaves a lot to be desired. Enter IOS FastScan.

Glidewell Laboratories has been the main clinical testing

facility for IOS Technologies’ IOS FastScan, and I

have spent a lot of time with it in my hands over the

last three years. Besides the fact that it might be the

fastest scanner for digital impressions, I think ROI

will be the feature dentists love most. For any monolithic

IPS e.max ® or BruxZir ® IOS FastScan digital file

you send to the lab, you will save $27 — that’s comprised

of $7 savings on inbound shipping, $10 savings

on impression material, and $10 off the restoration

list price because it can be digitally fabricated without

making a model. No other scanning system gives you

the ability to save this much on every crown you scan.

In fact, many digital systems actually cost you more.

Technology, Inc.

12 www.chairsidemagazine.com

Are You Using


or Counterfeit

Dental Products?


Gordon J. Christensen, DDS, MSD, Ph.D

14 www.chairsidemagazine.com

Most people find it difficult to pass up a bargain, and

dentists and dental staff members who select and order

products are no exceptions. It is relatively common to see

dental products offered in dental magazines and journals

at discounts of 10 percent to 50 percent.

Are you using products purchased at significant discounts?

As staff members typically handle the ordering of supplies

in most dental offices, do you, the dentist, even know if you

are using such products?

A key question to ask is: How can some dental retailers sell

dental supplies at deeply discounted prices, while others

continue to sell at the recognized market level? Deeply discounted

products may not be legitimate ones produced by the

manufacturer from which you think you are buying. You may

be using “gray-market” or even counterfeit products without

knowing it.

Gray-market products include branded goods intended by the

brand owner for one national market that are diverted and

resold by unauthorized distributors to another market. Counterfeit

products, on the other hand, never originate from the brand

owner. Counterfeiters simply pass off fake materials under the

guise of a well-known product. There is a surprising lack of published

information on this subject. However, a few related articles are

interesting. 1–4

A key question to ask is: How can

some dental retailers sell dental

supplies at deeply discounted

prices, while others continue to

sell at the recognized market

level? Deeply discounted

products may not be legitimate

ones produced by the

manufacturer from which you

think you are buying. You

may be using “gray-market”

or even counterfeit products

without knowing it.

Large dental companies, such as 3M ESPE (St. Paul, Minn.), DENTSPLY (York, Pa.) and Kerr (Orange, Calif.), deal

with gray-market and counterfeit products regularly, and some find it difficult to estimate what percentage they

represent of products sold. Kirsten Edwards, director of clinical affairs for Kerr, estimated that approximately

5 percent to 8 percent of apparent Kerr products are gray-market or counterfeit (oral communication, Feb. 23,

2010). These products are sold under the pretense of being brand-name items.

Purchasing discounted dental products saves money, but is it worth the potential hazards of buying and using

such products? For example: Say you gross $600,000 per year with a 60 percent overhead before taxes, and your

supply expenses are equivalent to about 5 percent of your gross income, or about $30,000 for the year. Assuming

you save 10 percent off your supply cost, you’ll save $3,000 in a year, or $250 per month. However, what if

these discounted products are expired, altered or even counterfeit, and you have a material failure — such as

postoperative tooth sensitivity — in a group of patients? Additionally, the legal liability associated with using

a dental material that is not approved for sale in the U.S. or cannot be tracked back to its origin of sale is a

significant threat. Even if you determine the cause of the problem, have you really saved anything? Is it worth

the $250 per month savings? To whom do you go when the product does not meet its expressed purpose or

you have problems with patient complaints?

In this article, I discuss the prevalence of gray-market and counterfeit products and manufacturers’ concerns

about them; the need for communication between the dentist and the staff member(s) ordering the dental

products; how to identify gray-market and counterfeit products; and, most importantly, what to do to avoid

the problem.

Are You Using “Gray-Market” or Counterfeit Dental Products?15

There are other reasons I

prefer to purchase from these

major distributors. By doing

so, I know that in spite of

often paying somewhat more

for some items, I have their

repair support. Additionally,

I can ask their local sales

representatives about the

properties of specific products

and the acceptance or

rejection that products are

receiving in my community.




The U.S. Food and Drug Administration (FDA) regulates

the dental industry, ensuring that dental medical devices —

or the dental products used and placed in patients’ mouths

— meet accepted standards. The FDA also approves manufacturers’

claims and inspects manufacturing facilities for

ongoing compliance.

Manufacturers’ concerns about gray-market and counterfeit

products are about more than financial loss. They also center

on potential health risks for patients and negative brand

perception among clinicians who might use a gray-market or

counterfeit product and not get the expected clinical result.

3M ESPE Global Director of Channel Sales Kathy Gaertner

stated that the company sees the presence of unauthorized

intermediaries selling products that are not authorized for

sale in the U.S. (written communication, Feb. 23, 2010). These

items often are products intended for sale in developing countries

that have been repackaged and sent back to the U.S. for

sale to American dentists. When products not cleared for sale

in the U.S. are repackaged, you cannot be guaranteed that you

are buying the product you think you are buying. Warning and

traceability information may be missing, and the products may

no longer comply with regulatory requirements. Oftentimes, these

repackaged products are outdated or expired with a fraudulent

extended expiration date. The gray-market product may have been mishandled,

resulting in compromised product efficacy.

The only way to know you’re getting the 3M ESPE product quality you trust is to purchase [products] through

certified 3M ESPE distributors,” stated Gaertner.

DENTSPLY Chief Clinical Officer Dr. Linda Niessen described the company’s concerns about gray-market and

counterfeit products not providing the clinical outcomes that dentists have come to expect from DENTSPLY

brands (written communication, Feb. 23, 2010). Company personnel routinely see examples of discounted

noncompliant, expired or repackaged DENTSPLY products. They have seen cases in which early generations of

products, no longer registered with the FDA, are acquired in developing markets. These products are imported

illegally into the U.S. and resold to U.S. dentists as the newest product under different brand names. The primary

packages are labeled clearly as the early-generation product, while the directions for use and the invoice

falsely claim the product to be the newest-generation product. Gray-market activity not only creates a clinical

risk exposure for dentists, but also deprives their dealer partners of the opportunity to supply a quality product

behind which the manufacturer will stand. DENTSPLY has 22 authorized dealer partners; Dr. Niessen said

that if a DENTSPLY product comes from anyone else, it is likely to be counterfeit or altered.

Kirsten Edwards of Kerr stated that counterfeit OptiBond ® Solo Plus , Herculite ® and other popular Kerr

brands have been sold through unauthorized dealers (oral communication, Feb. 23, 2010). To the naked eye,

the packaging appears to be identical to the official company packaging. This includes lot codes that match

16 www.chairsidemagazine.com

legitimate codes for lots sold to authorized dealers. The company cautions dentists that if the price of a Kerr product

is significantly below standard U.S. or Canadian pricing, the product is likely to be gray-market or counterfeit and

could violate civil and criminal laws. Kerr also has filed a citizen petition with the FDA seeking action against several

unauthorized dealers that have been found distributing gray-market or counterfeit Kerr products. As of the publication

of this article, no action has been taken by the FDA to stop this activity.

It is obvious that unscrupulous, profit-motivated distributors can find many ways to simulate popular products and

sell them to dentists at discounted prices. The Internet has made this easier.



How can we identify gray-market and counterfeit products before they arrive at our office? In order to reduce or

eliminate this problem, dentists must change their behaviors.

Who in your office orders and purchases dental supplies? If you are a typical dentist, dental supplies are ordered,

purchased, shelved and placed in the operatory by a competent, knowledgeable dental assistant or, in some offices,

by the office manager. These loyal staff members are eager to please you by making inexpensive supply purchases.

Bargain rates of 10 percent or more off standard prices are as attractive to them as they are to you.

How many relatively unknown companies vie for your supply business? Advertisements come through your office

on a daily basis, and staff members collect these ads to make choices about the company from which to order.

Do you routinely meet with the staff member in charge of ordering to review and confirm the brands and prices

of the products? Does this staff member know the necessity of confirming that the distributor is an authorized

dealer? It is doubtful that in an organized office, in which the dentist has delegated responsibility to staff members,

that the dentist and the staff member who orders supplies meet to discuss product ordering. In my opinion,

such a meeting would reduce or eliminate the problem of gray-market and counterfeit product proliferation.

It is time for every dentist to hold these meetings.

I suggest that on a scheduled basis, the dentist and the staff member ordering supplies meet to determine

desired brands and needed quantities of these brands of products. Before the meeting, the staff member can

collect information about the various companies from which specific categories of products are available and

have the information ready for the dentist’s review at the meeting. This preparation will reduce the time needed

for the meeting, which can be brief.

Manufacturers sell their products either directly to you or through their authorized distributors and dealer

partners. Ordering only from known, authorized retailers will ensure that the products are legitimate and from

respected manufacturers.

All major manufacturers have lists of authorized distributors available. If you have a question about the legitimacy

of a discounting distributor, you can verify that the distributor is an authorized retailer by contacting the

product’s manufacturer.

Purchasing from the major U.S. distributors such as Benco Dental, Burkhart Dental Supply, Darby Dental

Supply, Goetze Dental, Henry Schein and Patterson Dental helps ensure that the supplies are legitimate, and

covered by warranties and manufacturer support. There are other reasons I prefer to purchase from these

major distributors. By doing so, I know that in spite of often paying somewhat more for some items, I have

their repair support. Additionally, I can ask their local sales representatives about the properties of specific

products and the acceptance or rejection that products are receiving in my community.

Are You Using “Gray-Market” or Counterfeit Dental Products?17



There are several ways to identify potentially gray-market or counterfeit dental supplies.

Low price. The product is selling for significantly below the known market price. You may determine the market

price by looking in the online or printed catalogs of the major dental retailers noted earlier.

Unknown distributor name. You know the major retailers, and you know the major private-label independent

companies that do not sell via the major retailers. If the company selling the product does not have a recognizable

name, you have reason to be suspicious. Do some homework to learn about the supplier, particularly if you are

purchasing online, before you make a purchase decision.

Suspicious packaging. If you attend a dental meeting and see a significantly discounted apparently identifiable

product, you should consider the following relatively easily observable characteristics. Examine the printing on

the package. Is it smeared, irregular, uneven or not of the quality you have previously observed on packaging

of products with the same brand name? Is the product name current or a previous name you remember from an

earlier version of the product? Is the bar code or any aspect of the product description blocked out? Is the product

marked “For export only” or “Not registered for sale in the European Union or United States”? Be sure the label on

the product matches the product name on the directions for use. Is the language on the package something other

than English?

Check the expiration date. Is the product expired? Does it appear that the expiration date has been changed?

If you become suspicious of a product while attending a convention, go to a known authorized distributor of the

brand in question, examine its packaging and ascertain the price of the product. You may see an immediately

apparent difference.



I suggest the following preventive actions to avoid the problems potentially related to purchasing gray-market

or counterfeit products.

Use authorized distributors. If you have any question about the legitimacy of a distributor, call the manufacturer

and request a verification of the distributor’s authenticity.

Expect to pay a fair market price for products. Authorized distributors offer occasional price reductions as

specials. However, brand-name products have an expected fair price that does not vary significantly among


Avoid deeply discounted prices. If the price is too good to be true, you probably are looking at a suspect


Investigate. If you have questions about any product, have your staff investigate the retailing company by

visiting the manufacturer company’s website and comparing the image and description of the product in

question with the manufacturer’s information. Most manufacturing companies feature images of their products

on their websites.

In addition, dental manufacturers themselves are taking steps to prevent gray-market or counterfeit products.

18 www.chairsidemagazine.com

They are using new types of labeling to facilitate the identification of gray-market and counterfeit products. When these

products are identified, the manufacturers are taking action against the vendors to remove them from the market.


As verified by dental manufacturers, there is no question that gray-market and counterfeit products are being

distributed and sold on the U.S. dental market. “Buyer-beware” policies should prevail in dental offices. Dentists

should meet with and assist office staff members in selecting products and identifying authorized product distributors.

Questionable products and unknown, unauthorized distributors should be avoided. Although discounted dental

products are available, the cost of overcoming the potential problems for patients caused by inferior products can

be far greater than the amount saved. CM

Dr. Gordon Christensen is the director of Practical Clinical Courses and cofounder of the nonprofit Gordon J. Christensen CLINICIANS REPORT ® . Contact him at

801-226-6569 or info@pccdental.com.


1. Santerre P, Conn A, Teitelbaum B. Toronto Academy of Dentistry winter clinic panel discussion on gray-market and counterfeit dental materials.

J Can Dent Assoc. 2008;74(3):233–35.

2. Lewis K. China’s counterfeit medicine trade booming. Can Med Assoc J. 2009;181(10):E237–38.

3. Gautam CS, Utreja A, Singal GL. Spurious and counterfeit drugs: a growing industry in the developing world. Postgrad Med J. 2009;85(1003):251–56.

4. Schweim JK, Schweim HG. Internet pharmacies and counterfeit drugs (in German). Med Klin (Munich). 2009;15;104(2):163–69.

Christensen GJ. Are you using “gray-market” or counterfeit dental products? JADA. 2010;141(6):712–15. Copyright ©2010 American Dental Association.

All rights reserved. Reprinted by permission.

Are You Using “Gray-Market” or Counterfeit Dental Products?19

Monolithic Versus

Bilayered Restorations:

A Closer


Gregg Helvey, DDS, MAGD


The all-ceramic crown was developed in the early 20th century when Charles H. Land patented the allporcelain

“jacket” crown to improve esthetics. This procedure consisted of rebuilding the missing tooth

with a porcelain covering, or “jacket” as Land called it. To solve the product’s strength problems, Abraham

Weinstein in the late 1950s introduced a metal core to which porcelain was fused, thus creating the

ceramo-metal crown. Throughout the years, the metal has been substituted with different materials to

achieve a more esthetic result. Problems have been reported with the fusion between the ceramic and the

core, which have resulted in debonding of the veneered ceramic. Further investigations in dental material

science have produced tremendous advances in unveiling aspects that have been taken for granted, such

as the bond strength between different materials that comprise the crown restoration. Recently, a lithium

disilicate material that was once used solely as a core material was introduced as an all-ceramic alternative.

This article discusses the strength factors that comprise a monolithic and bilayered ceramic restoration.

Monolithic Versus Bilayered Restorations21

Advances in the field

of dental ceramics

can take time to find

acceptance in the dental

community. Ceramic materials

are usually employed in

higher-end procedures, and

the clinician is compelled to

deliver a product that has a

proven durable and esthetic

track record. Materials and

procedures must have the

science behind them and

the endorsement of leading

clinicians before being introduced.

Only then can these

materials become part of

the dentist’s restorative armamentarium.

For years, the ceramo-metal

restoration has been the

gold standard in crown &

bridge procedures. Although

durable and time-tested, this

type of restoration may not

be the most esthetic. For

years, patients have asked

for metal-free restorations,

and the industry has accommodated

this request with

various resin composite and

ceramic systems.

These newer systems have an effect on the actual fabrication

methods. Traditionally, the ceramo-metal restoration

is constructed by casting a metal coping and applying

a porcelain opaque layer followed by layering veneering

porcelain. Newer methods have bypassed the coping

fabrication step. Using a vacuum-pressing system, allceramic

restorations are waxed to full contour and

invested, wax burnt out and hot-pressed, creating a solid

ceramic restoration. The question remains if these allceramic

monolithic forms can endure the rigors of an

intraoral restoration as well as the bilayered porcelain-tometal


All-Ceramic Crowns: Bilayered Versus Monolithic

Numerous bilayered crown systems that are supported

by a substructure core are available. Various materials are

used to create these substructures, e.g., metal alloys, alumina

and zirconia. Often, ceramo-metal crowns have been

used because of their strength, biocompatibility and esthetics.

1 Patient demand for more esthetic restorations has

Figure 1: For several decades, the ceramo-metal crown

has been the “workhorse” restoration.

Figure 2: Anterior ceramo-metal crowns display the less

esthetic opacity that is sometimes evident in metal-substructure


gradually increased, leading

to greater use of nonmetallic,

high-strength core materials.

These esthetic core materials

include alumina, zirconia,

zirconia-toughened alumina,

magnesium aluminate spinel

and lithium disilicate. Once

the cores are fabricated, the

laboratory technician applies

veneering porcelain to create

the final esthetic restoration.

2,3 Yet all of these porcelain-laminated

systems share

a common mode of failure:

fracture of the veneering

ceramic from its core.

There are three basic configurations

for restorative

crowns: bilayered ceramometal,

bilayered ceramozirconia

and monolithic

lithium disilicate. While numerous

studies are cited

in the literature, specific

comparative tests uniformly

conducted on all three

systems are difficult to find.

The testing methods, sample

sizes and the instrumentation

used in the studies are

variables that must be considered.

Therefore, strength comparisons of different

studies can be misleading. However, after reviewing the

body of literature, a different perspective may be gained

as to the overall strength of each system, rather than one

particular asset.

Ceramo-Metal Restorations

Through the years, replacement and reinforcement

of the human tooth has evolved from a monolithic design

(gold crown) to a bilayered design (ceramo-metal

and ceramo-zirconia) and again to a monolithic design

(lithium disilicate/full zirconia). In the past several

decades, the workhorse restoration is the ceramo-metal

crown: a metal substructure in which ceramic material

is layered or pressed to form the anatomic shape of

the restoration (Figs. 1, 2). The weakest point is the

ceramo-metal interface. The exact mechanism of porcelain-to-metal

fusion is unknown; however, at least four

theories have been discussed.

22 www.chairsidemagazine.com

1. The theory of van der

Waals forces 4 refers to the

bonding of materials created

by the attraction of charged

atoms that do not exchange

electrons. These secondary

forces are generated more

by a physical attraction between

charged particles than

by an actual sharing or exchange

of electrons in primary

(chemical) bonding. 5

2. The theory of mechanical

retention of ceramic to

a metal coping is derived

from the microscopic irregularities.

The contribution of

micromechanical bonding

may be relatively limited because

ceramic does not require

a roughened area to

bond. 5 Lacy 4 has shown that

ceramic will fuse to a wellpolished

metal surface; however,

some surface roughness

does contribute to an

increased bond. 6–8 Therefore,

mechanical retention alone

is probably not sufficient to

entirely explain how dental

ceramic adheres to a metal

substrate. 5

3. Bonding of porcelain to metal by means of compression

is the third theory. Dental porcelain, like most brittle

materials, is strong in compression but relatively weak

when subjected to tensile stresses. Its tensile strength

is approximately 4 percent of its compressive strength. 9

Compressive stress in the layering porcelain reinforces

the fracture strength. A thermal mismatch between

the coping and the porcelain leads to compressive or

tensile stress depending on whether the coefficient

of thermal expansion of the porcelain is higher or

lower than that of the coping. 10 The expansion of the

porcelain must be lower than that of the coping to

generate compressive stress during cooling. 11 The

development of compressive forces in the porcelain and

tensile forces in the metal is due to the difference in contraction


4. Chemical bonding is the final generally accepted theory

as the primary mechanism of ceramic-to-metal attachment.

12–14 The mode of bonding involves the metal surface

Figure 3: Ceramo-metal failures are multifactorial and

can be related to a combination of reasons.

The literature cites studies

observing various ceramometal

failures. Failure

rates range between

5 percent and 10 percent

over 10 years.

oxides dissolved by the applied

ceramic opaque layer.

This results in an atomic contact,

whereby shared electrons

form ionic and covalent

bonds between the oxide layer

on the metal surface and

the ceramic opaque layer. 12,13

Ceramo-Metal Failures

The literature cites studies

observing various ceramometal

failures. Failure rates

range between 5 percent and

10 percent over 10 years. 15

Strub et al. found failure

rates of ceramo-metal restorations

as high as 3 percent

over five years. 16 Hankinson

and Cappetta 17 and Kelsey

et al. 18 found a failure rate

between 2 percent and

4 percent that occurred after

two years. They also

found that, due to a repetition

of consistent occlusal

contacts, after four to five

years the failure rate rose to

20 percent to 25 percent.

A ceramo-metal failure is a

multifactorial problem related

to a combination of reasons 1 (Fig. 3). Some studies

attribute failures to environmental factors, particularly

moisture. A moist environment was found to reduce the

ceramo-metal strength by 20 percent to 30 percent. 19 In

the presence of moisture, the silicon-oxygen bond between

metal and ceramic weakens and promotes failure

because of water propagation at the crack tip. 20 Most

frequently, ceramic failures are related to the cracks in

the ceramic. 1 Small scratches on the ceramic surface can

act as notches where the concentration of stress can exceed

the theoretical strength of the ceramic. As the crack

propagates through the material, the stress concentration

is maintained at the crack tip until the crack moves

completely through the material. 21

Technical errors in the laboratory can also account for

ceramo-metal failures. A void or pore that remains after

the fabrication can be the site of weakness and eventual

failure. 22 Porosity does occur between ceramic particles

during the ceramic application, and the technician should

make every effort to minimize this.

Monolithic Versus Bilayered Restorations23

Diaz-Anold et al. found several

reasons for failure, including

faulty metal structure

design and incompatible coefficients

of thermal expansion

between the metal and

the ceramic material. 23

Another reason was insufficient

metal support for the

ceramic, leading to unsupported

excessive thickness

of ceramic, technical flaws

in the porcelain application,

and occlusal forces or trauma.

Ceramic material properties,

including microstructure,

crack length, fracture

toughness and applied stress

intensity, also contribute to

failure. 23

Usually, a catastrophic failure

is the result of crack

initiation and propagation.

Llobell et al. described reasons

for intraoral ceramic

failure: impact load, fatigue

load, improper design and

microdefects within the material.

They also found that

masticatory repetitive forces,

including parafunctional

occlusion, created alternating

forces, contributing to

the fatigue of ceramo-metal

restorations. 24 Typically, one

factor alone does not cause

ceramo-metal catastrophes;

rather, the cumulative effect

of a large number of comparatively

small loadings

leads to failure. 1

Bond Strength of

Porcelain to Metal

The ideal test to determine the bond strength between

ceramics and metal does not exist, although several

methods have been used. 25 Several tests have been employed

to evaluate the ceramo-metal bond strength 26 :

shear test (maximum stress that a material can withstand

before failure in shear), 27 planar shear test (opposing forces

are applied parallel to the cross-sectional area under

test), 25 tensile, 28 flexural 29 and torsional strength. 30 Chong

Figure 4: Before the zirconia substructure is placed on

a solid working model, the separating medium has been

applied prior to wax application.

Sufficient bond strength

between veneering

ceramic and zirconia

framework substructures

is a concern for longterm

success. Chipping

of the veneering ceramic

constitutes clinical failure

and has been reported

to occur at a rate of 13

percent during a threeyear


and Beech 27 proposed the

circular-planar surface shear

test, which provided standardization

and ease in specimen

fabrication. 31

Scolaro et al. 26 tested different

ceramics that were

bonded to a palladium-silver

alloy (Pors-On 4; DENTSP-

LY Ceramco; Burlington,

N.J.). They used Ceramco

(DENTSPLY), Noritake Super

Porcelain EX-3 (Cincinnati,

Ohio) and VITA VMK ®

68 (Vident; Brea, Calif.).

The shear bond strength

results were: Noritake

(28.96 MPa ± 6.92 MPa),

Ceramco (28.20 MPa ±

8.65 MPa) and VITA VMK 68

(24.11 MPa ± 6.27 MPa).

Akova et al. 32 compared the

bond strength of layering

porcelain to cast Ni-Cr and

Co-Cr alloys to laser-sintered

Co-Cr alloy. In this study, the

mean shear bond strength

was the highest for the base

metal Ni-Cr (81.6 MPa ±

14.6 MPa) and slightly less for

the Co-Cr base metal

(72.9 MPa ± 14.3 MPa). The

shear bond strength of the

laser-sintered Co-Cr metal

was 67 MPa ± 14.9 MPa.

Joias et al. 31 tested the shear

bond strength of a ceramic

to five commercially available

Co-Cr alloys. The same

ceramic (VITA Omega 900,

Vident) was bonded to

each alloy. The shear bond

strength test was performed

in a universal testing machine with a crosshead speed of

0.5 mm/min. The ultimate shear bond strength ranged

from 61 MPa to 96 MPa.

According to Powers and Sagaguchi, 26 an adequate bond

occurs when the fracture strength or fracture stress

(the stress at which a brittle material fractures) is above

25 MPa. Other studies also have accepted a sufficient bond

for metal-ceramics when the fracture stress is greater

24 www.chairsidemagazine.com

than 25 MPa. 1,33–35 Because

this value represents the

limit of the test, it could be

argued whether this were a

true representation of adequacy.

36 As previously noted,

some ceramo-metal systems

in other studies have tested


A recently introduced laboratory

method of ceramic application

to metal is the use

of the lost-wax technique, in

which a pressable ceramic is

applied to an opaque metal

or zirconia core (Figs. 4–7).

This is a simpler and quicker

method than the conventional

technique and eliminates

the need for the 20 percent

shrinkage compensation with

traditional porcelain firing. 37

Venkatachalam et al. 38 compared

the debond/crack

initiation strength of a leucite-based

low-fusing ceramic-pressed-to-metal


feldspathic porcelain-fusedto-metal.

The metal specimens

included gold-palladium

alloy and chrome-cobalt

base metal alloy divided into

two groups of 20 samples.

The mechanical testing method

used in this study was the

Schwickerath crack-initiation

three point bending test standardized

by the International Organization for Standardization

(ISO), 39 which is now considered the gold standard

for examining metal-ceramic bond strength. 38 Their

findings showed a mean debond strength for feldspathic

porcelain to the base metal alloy of 36.11 MPa ± 2.31 MPa,

while the feldspathic porcelain to the gold-palladium

alloy demonstrated a mean bond strength of 42.64 MPa

± 1.94 MPa. For the ceramic-pressed-to-metal specimens,

the mean debond strength of the base metal combination

was 37.47 MPa ± 6.02 MPa and 47.94 MPa ± 3.92 MPa for

the gold-palladium samples.

Ceramo-Zirconia Failures

The actual mechanism of bonding ceramic to zirconia

substructures is not completely understood, nor is the

Figure 5: After wax is injected onto the zirconia substructure,

the margins are refined on the removable die.

Figure 6: The undersurface of a single zirconia-based

crown after the waxing phase is completed

manipulation of surface

treatment of zirconia in the

quality of the bond. 40–42 Sufficient

bond strength between

veneering ceramic and zirconia

framework substructures

is a concern for long-term

success. 10 Chipping of the

veneering ceramic constitutes

clinical failure and has

been reported to occur at

a rate of 13 percent during

a three-year observation. 43

In a follow-up study, Sailer

et al. found the failure rate

increased to 15.2 percent

during a five-year period. 44

One approach to enhancing

ceramic-to-zirconia bond

strength is sandblasting,

which increases the surface

roughness and provides

undercuts. 38–40 Conversely,

Kosmac et al. 45 and Guazzato

et al. 46 found sandblasting

adversely affects the mechanical

strength of the zirconia

by initiating a phase transition

(tetragonal to monoclinic

form) and probably has

a detrimental effect on the

bonding capacity. This phase

transition of tetragonal zirconia

to monoclinic zirconia

results in a significantly

lower coefficient of thermal


Fischer et al. 47 investigated the effect of different surface

treatments on the bond strength of veneering ceramics

to zirconia. Their study assessed the influence of treating

the zirconia surface by polishing, sandblasting, silica

coating and applying a liner. They also studied the impact

of regeneration firing, which entails firing the zirconia

framework for 15 minutes at 1,000 degrees Celsius

prior to veneering. This re-establishes the tetragonal lattice

after sandblasting or grinding to obtain better bond

strength. 48 Five different layering ceramics were used.

The shear strength of all the types of surface conditions

was 23.5 MPa ± 3.4 MPa to 31 MPa ± 7.1 MPa. In all specimens,

the fracture started at the core-veneer interface

and continued into the veneering ceramic, which

remained on the core. The weakest link was not the

Monolithic Versus Bilayered Restorations25

interface, but the veneering

ceramic itself. This study

concluded that increased

surface roughness did not

enhance shear strength, the

application of a liner did not

improve shear strength, and

regeneration firing decreased

the shear strength. The recommendation

to realize the

benefit of high-strength zirconia

as a framework was

to strengthen the veneering


Although the zirconia substructure

is fracture-resistant,

a high percentage of failures

of the ceramo-zirconia restoration

are found in ceramic

chipping and delamination.


A randomized, controlled

clinical trial showed the performance

of 3-unit posterior

prostheses using three ceramo-metal

fabrication methods

and five major companies’

zirconia technologies. 52

The researchers evaluated

the framework and the veneering

ceramics. The report

showed veneering ceramic

fractures were five times

more prevalent with ceramic

formulations used on zirconia

versus those employed

on metal.

In another study, Taskonak

et al. 53 determined the site

of crack initiation and the

causes of fracture in failed

zirconia-based ceramic fixed

partial dentures. Fractures

that had origins on the ceramic

veneer surface had

failure stresses between 31

MPa and 38 MPa.

Figure 7: Facial view of the finished restoration

Aboushelib et al. 54 stated that the bond strength between

veneer ceramic and the zirconia framework is the weakest

component in the layered structure. To enhance the final

esthetics of layered zirconia-based restorations, colored

The lithium disilicate

microstructure has

numerous small

interlocking plate-like

crystals … This crystal

size and orientation

causes cracks to deflect,

branch or blunt, which can

account for the increase

in flexural strength and

fracture toughness

compared to leucitereinforced


pigments are incorporated

into the surface of the zirconia

framework (Fig. 8).

The objective of this study

was to investigate the effect

of zirconia type (white or

colored) and its surface finish

on the bond strength to

two veneer ceramics. They

found the addition of coloring

pigments resulted in a

significantly weaker bond

strength compared to the

white zirconia frameworks.

In a comparative study,

Guess et al. 55 evaluated the

shear bond strength between

various commercial zirconia

core and veneering ceramics

and the effect of thermocycling.

Using the Schmitz–

Schulmeyer test method,

they evaluated the coreveneer

shear bond strength

of Cercon ® base to Cercon

Ceram S; VITA In-Ceram ®

YZ cubes to VITA VM9; and

DC-Zirkon to IPS e.max ®

Ceram (Ivoclar Vivadent;

Amherst, N.Y.). As a control

specimen, they used

a ceramo-metal system,

DeguDent U94 (DeguDent,

a DENSTPLY Company)

to VITA VM13. Half of

each specimen group was

thermocycled at 5 degrees

Celsius to 55 degrees Celsius

for 20,000 cycles. Their

results demonstrated the

shear bond strength values

of 12.5 MPa ± 3.2 MPa for

VITA In-Ceram YZ Cubes/

VITA VM9, 11.5 MPa ±

3.4 MPa for DC-Zirkon/

IPS e.max Ceram and 9.4 MPa ± 3.2 MPa for Cercon

base/Cercon Ceram S. The specimens that were thermocycled

did not show any significant differences.

The control ceramo-metal specimen showed a higher

shear bond strength, regardless of thermocycling, of

27.6 MPa ± 12.1 MPa.

26 www.chairsidemagazine.com

Monolithic Restorations:

Lithium Disilicate

The first all-ceramic restorative

system was introduced

in 1903 by Charles Land. 56

The so-called porcelain

“jacket” crown was fabricated

with high-fusing feldspathic

porcelain. Although it was

noted for natural esthetics,

the failure rate was high,

probably due to the low

strength of the porcelain.

57 Interest in all-ceramic

restorations has grown

throughout the years.

Developments have included

several bilayered systems consisting of a ceramic-type substructure

interfaced with a veneering ceramic.

Recently, a monolithic approach was introduced using

lithium disilicate glass ceramic (e.g., IPS e.max Press and

IPS e.max CAD). This material has two forms: a homogeneous

ingot with various degrees of opacity used with

hot-pressed technology and a pre-crystallized block used

with CAD/CAM technology. Both forms can be used in a

full anatomical contour method with the application of

stain and glaze or a cutback and layering technique.

The CAD milling blocks are produced for distribution

using a glass technology. This process prevents the

formation of defects and voids throughout the block and

allows for an even distribution of the pigmentation. This

partial crystallization process forms lithium-metasilicate

crystals, which provide sufficient strength for milling.

According to the manufacturer, the partially crystallized

milling block has a microstructure consisting of 40 percent

lithium-metasilicate crystals, which are embedded

in a glassy matrix. The grain size of these crystals

ranges from 0.2 μm to 1 μm. At this point, the lithium

metasilicate block has a flexural strength of 130 MPa,

which is comparable to leucite-reinforced CAD/CAM

blocks (ProCAD, Ivoclar Vivadent) and feldspathic

CAD/CAM blocks (Vitablocs ® Mark II, Vident). 58 After

milling, the pre-crystallized restoration is placed in the

mouth and adjusted, if necessary. The restoration is then

crystallized during a 20-minute firing cycle using a twostep

ceramic furnace. Because the restoration can be

milled to full contour, there is no ceramic infiltration

process or veneering process. The restoration shrinks

0.2 percent during crystallization, which the computer

software accounts for during the milling process. During

the crystallization cycle, the lithium-metasilicate restoration

reaches a temperature of 840 degrees Celsius to

Figure 8: A shade base stain is applied to the zirconia

framework and fired prior to application of the veneering


850 degrees Celsius. During

the temperature rise, a

controlled growth of lithium

disilicate crystals occurs,

producing a transformation

of the microstructure that

results in an increase of the

final flexural strength of 360

MPa. This flexural strength is

approximately three to four

times stronger than leucitereinforced

glass ceramics. 59

This glass ceramic is comprised

of 70 percent prismatic

lithium disilicate crystals (0.5

μm to 5 μm long) dispersed

in a glassy matrix. 26 The lithium

disilicate microstructure has numerous small interlocking

plate-like crystals randomly oriented. This crystal

size and orientation causes cracks to deflect, branch

or blunt, which can account for the increase in flexural

strength and fracture toughness compared to leucite-reinforced

ceramics. 60

The manufacturer’s internal testing (Ivoclar Vivadent,

unpublished data, 2005) states the fracture toughness

(single-edge, V-notched beam testing) to be 2 MPa to 2.5

MPa m ½ and a modulus of elasticity of 95 GPa ± 5 GPa.

Bindl et al. 61 studied the fracture strength and fracture

pattern of three monolithic posterior crowns (lithium

disilicate, leucite glass and feldspathic ceramic) that have

a uniform thickness of 1.5 mm. They conventionally

cemented one half of the specimens while adhesively cementing

the other half on dies. For the conventionally

cemented crowns, load to fracture was 2,082 N, which

was significantly higher than that of the leucite glass or

feldspathic ceramic. When the specimens were adhesively

cemented to the die, the fracture load for the lithium

disilicate rose to 2,389 N, which was comparable to the

two other specimens. This study showed the strength of

the lithium disilicate when conventional cementing techniques

are employed. A manufacturer’s internal study comparing

the difference in failure load for monolithic and

bilayered crowns showed adhesively retained monolithic

lithium disilicate restorations had the highest load

to failure numbers. 66,67

The pressed form of the lithium disilicate has been shown

to have a modulus of elasticity ranging from 91 GPa 64

to 95 GPa ± 5 GPa (Ivoclar Vivadent, unpublished data,

2009). The flexural strength varies depending on the testing

method used. Using biaxial flexural strength tests

under dry and wet conditions, Sorenson et al. 65 found a

flexural strength ranging from 411.6 MPa to 455.5 MPa.

Monolithic Versus Bilayered Restorations27

Albakry et al. 64 measured

the biaxial strength with a

universal testing machine.

Twenty standardized disc

specimens (14 mm by 1.1

mm) were supported on

three balls and loaded with a

piston at a crosshead speed of

0.5 mm/min. until fracture.

The mean biaxial strength for

the lithium-disilicate specimen

was 440 MPa ± 55 MPa.

Depending on the testing

method, fracture toughness

of the lithium disilicate has

been shown to be at least or

greater than 3 MPa m ½ . Using

the indentation strength

technique, Guazzato et al. 66

found a fracture toughness

of 3 MPa m ½ . Albakry et

al. 67 measured the fracture

toughness of the pressed

lithium disilicate using two

different techniques: indentation

fracture and indentation

strength. They reported

a fracture toughness of

3.14 MPa and 2.5 MPa m ½ ,


Veneering Ceramic for

Lithium Disilicate

The coefficient of thermal

expansion of feldspathic

glass is closely matched to

alumina-based core material

(~7 ppm/degrees Celsius to

8 ppm/degrees Celsius) and,

consequently, can be used as

a veneering ceramic. Leucite

layering ceramics have the

same coefficient of thermal

expansion as the leucite core

material, therefore, posing

no problems in coefficient

mismatch. However, the coefficient

of thermal expansion

of lithium disilicate is

greater than 10 ppm/degrees

Celsius. As a result, a new

compatible layering ceramic

Comparison of the Flexural Strength of Pressed Ceramics

Figure 9: Comparison of different crown combinations

using different materials and monolithic lithium disilicate

during a cyclic loading test.

Restorative dentistry is

the science and art of

replacing human tooth

structure. The tooth is

comprised of enamel and

dentin, which individually

are low-strength materials

but, when combined,

their bond is unique and

can survive a lifetime.

Technology has not been

able to replicate nature’s


was developed. 26 The layering

material (IPS e.max

Ceram) is a low-fusing nanofluorapatite

glass ceramic. It

can be used with either the

pressed or CAD/CAM version

of the lithium disilicate

core and does not contain

feldspar or leucite.

The light refraction gives the

lithium disilicate material

a natural appearance and

can be used in a monolithic

form. In this state, the flexural

strength remains throughout

the entire restoration.

Surface colorants are available

to obtain the final shade

and characterization.

When in-depth characterization

is desired, a partiallayering

technique can also

be employed. At this point,

it can no longer be considered

monolithic because it

still comprises a majority

of the structure compared

to the zirconia-based restoration,

in which the bulk

of the restoration is the

veneered ceramic. A manufacturer’s

internal long-term

cyclic loading study compared

various restorative

dental materials for crowns

with monolithic lithium disilicate

crowns with and without

layered veneering porcelain.

68 After 300,000 cycles,

only the monolithic lithium

disilicate restorations —

regardless of whether layering

veneer porcelain had

been applied — did not

show any breakdown (Fig. 9).


Restorative dentistry is the

science and art of replacing

human tooth structure. The

tooth is comprised of enamel

and dentin, which individu-

28 www.chairsidemagazine.com

ally are low-strength materials but, when combined, their bond is unique and can survive a lifetime. Technology has

not been able to replicate nature’s bioengineering. For many decades, the ceramo-metal crown has been the mainstay

of restorative dentistry. Recently, the zirconia-based ceramic restoration was introduced with better esthetics and core

strength. Both systems are bilayered restorations with the bulk of the restoration consisting of a veneered feldspathic

ceramic or a leucite-reinforced, low-fusing pressed ceramic. In either case, the strength is dependent on the bond

strength at the interface between the core and its ceramic veneer. A new approach has been described in which a

ceramic with excellent optical properties and high flexural strength can be used in a monolithic design. The resulting

restoration possesses these qualities throughout its entirety as opposed to a restoration based on a bond between two

dissimilar materials — the layering ceramic and the core — in which bond strength is less than the individual parts of

the crown. Because nature’s bilayered tooth structure cannot be replicated, a monolithic approach may be the future. CM


The author would like to thank Ruth Egl, RDH, for her editorial contribution and to acknowledge Kramer Helvey for

his support.

Dr. Gregg Helvey is an AGD Master and part of an elite group of dentists who are also skilled ceramists. Contact him at 540-687-5855, www.gregghelveydds.com or



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30 www.chairsidemagazine.com

32 www.chairsidemagazine.com

Interview with Dr. David Hornbrook

– INTERVIEW of David S. Hornbrook, DDS, FAACD

by Michael C. DiTolla, DDS, FAGD

It was my pleasure to interview one of my clinical mentors, Dr. David

Hornbrook, for this issue of Chairside magazine. David is someone whom

I have followed since I graduated from dental school, when I started taking

his courses at Las Vegas Institute for Advanced Dental Studies (LVI),

PAC~live and the Hornbrook Group. Over the years, I’ve continued to

follow David and look up to him as a clinician and friend.

Interview with Dr. David Hornbrook33

Dr. Michael DiTolla: Good morning, David, it’s wonderful to have you here

with us.

Dr. David Hornbrook: Thanks, it’s great to be included.

IPS e.max has filled an

existing void in dentistry.

It is a highly esthetic

material — as you mentioned,

it approaches the

esthetics of anything we

have in dentistry right

now — and it’s amazingly

strong. We now have a

ceramic that’s four times

stronger than the ceramic

we’ve put on PFMs for

the last 60 years.

MD: People always say, “Now is the best time to be a dentist.” (With perhaps the

exception of the 1960s, before the air-driven handpiece was invented and everything

was belt-driven.) But as I reflect on my more than 20 years in practice, it seems

that things just continue to get better. Do you feel that 2011 is a great time to be

practicing dentistry?

DH: Absolutely. There are two things we need to look at. One is, obviously,

that the economy has changed a little bit. There may be people reading this

who say, “I’m not doing what I was doing two years ago in smile designs and

discretionary dentistry.” But if we eliminate that aspect of it, this is the best

time to be a dentist.

The advantage of where we are now is that we are no longer faced with the

many limitations and compromises we’ve historically faced during treatment

planning. Materials are more esthetic, and adhesive dentistry has allowed us

to be more conservative. Today, the only limitations we face are those of the

clinician’s imagination.

MD: Well, let’s back up to what you said about the economic slowdown. I can tell

you that, at least from the lab’s perspective, the economic slowdown over the past

two years did happen — you are right on the money. If we look at our veneer sales,

they definitely decreased over that time period. No one is imagining that. This isn’t

a rumor running rampant through dentistry; there was a serious cutback in the

number of elective cosmetic procedures.

Over the past two years here at the lab, only a couple of products have grown.

One of them is an esthetic product (in the sense that it’s a great-looking product):

IPS e.max ® (Ivoclar Vivadent; Amherst, N.Y.) crowns. IPS e.max veneers have grown

as well. People obviously still need full-contour restorations, so those may not be

elective. At any rate, IPS e.max has continued to show an impressive growth curve

over the last couple years. I’m guessing you’re a pretty big fan of this product. Tell

me a little bit about the impact IPS e.max has had on your practice.

DH: You are absolutely right to say that I’m a big fan of IPS e.max. It’s an

unbelievable material. For those readers who aren’t familiar with this product,

IPS e.max is a lithium disilicate material that can be waxed and pressed or

fabricated using CAD/CAM.

When waxed and pressed, kind of like we’ve done with IPS Empress ® (Ivoclar

Vivadent) and leucite-reinforced ceramics for the past 20 years, we use the

lost-wax process (just like we’d cast gold). It can also be made using CAD/

CAM technology, whether in the office with CEREC ® (Sirona Dental Systems;

Charlotte, N.C.) or E4D (D4D Technologies; Richardson, Texas), or in the dental


IPS e.max has filled an existing void in dentistry. It is a highly esthetic material

— as you mentioned, it approaches the esthetics of anything we have in

dentistry right now — and it’s amazingly strong. We now have a ceramic that’s

four times stronger than the ceramic we’ve put on PFMs for the last 60 years. I

mentioned earlier about options in treatment planning: Now I can look at even

a second molar on a bruxer that has decreased vertical dimension and give the

patient a restoration that is esthetic, conservative and strong.

34 www.chairsidemagazine.com

MD: I distinctly remember placing my first IPS e.max crown.

It was on a friend’s wife, and it was at the end of a two-year

period in which I did nothing but zirconia-based restorations.

We were struggling to blend the zirconia restorations

with the adjacent teeth because we were dealing with coping

shade issues and with dentists under-reducing teeth, especially

in the gingival third.

When lithium disilicate came out, I must admit I was a little

suspect. Ivoclar was releasing this material for the third time,

and I wondered if it would work. The first IPS e.max crown

I put in was so beautiful that it blew me away. It was the

kind of thing you looked at and said, “Wow. If this is going

to stand up to the types of wear and tear we see in the mouth,

this material is going to be successful.”

How neat is it that a material can be used for almost any clinical

indication — inlays, onlays, crowns and even veneers?

I recently heard a rumor that some of the esthetic institutes

were thinking of switching over to IPS e.max veneers. What

are you teaching in your clinical course now, and how do

you feel about IPS e.max veneers?

DH: Well, by the time this article is published, my opinion

may change based on the fact that Ivoclar is introducing

even better ingot and block shades. I know some people

will read this and say: “IPS e.max? It’s kind of gray. It’s

kind of opaque. It doesn’t look as good as IPS Empress …”

That was the IPS e.max of a year and a half ago, when

Ivoclar didn’t have available the many translucent and

esthetic ingots that are now offered for CAD/CAM or for

pressing. And now they’ve introduced ingots that mimic

what we’ve always seen with Empress, which is what I

would call my standard for anterior esthetics. To answer

your question, today I’m still a fan of IPS Empress in the

anterior and it is still my “go to” material. If you came into

my office or into my teaching center and you were going

to do six, eight, 10 veneers, IPS Empress would still be my

first choice. I just think it interacts with light a little better

than lithium disilicate. But as we get more experience

with the new Value ingots, that preference may change. I

seated 10 maxillary anterior veneers this week using the

new V1 ingot, and the case was beautiful.

We are also now doing prepless and very minimal-prep

IPS e.max veneers, because at 0.2 mm or 0.3 mm thin,

this material exhibits incredible marginal integrity. Even

being this thin, they are very high strength and very easy

for the laboratory to finish down at the margins. We’re

doing anterior 3-unit bridges in IPS e.max, and we’re getting

esthetics that approach IPS Empress. So we’re still

teaching IPS Empress. But, then again, three months from

now when you ask me this question I might say, “Who’s

using IPS Empress anymore? Not me.” This is what makes

dentistry so exciting and fun!

MD: My personal viewpoint is that if I’ve got to do a veneer

on tooth #9, and tooth #8 is a virgin tooth, I am going to use

IPS Empress. Like you, I don’t think there’s anything as lifelike

as IPS Empress somewhere between 0.3 mm and 0.6 mm

thick. It just looks more like natural tooth structure than anything

else. But I’ve started to change a little bit — and I’m

not as demanding esthetically as you are. When I get to an

8-unit veneer case, I like the idea — and we can see from

the numbers that dentists liked the idea, too — of having a

veneer material that’s three times as strong as IPS Empress.

Dentists have had problems with chipping and they’ve had

some breakage. Maybe it was due to poor prep design or not

checking the occlusion close enough, but dentists seem to like

the idea of having a stronger material. And, of course, when

you have six, eight, 10 veneers lined up next to each other, it’s

not the same kind of thing as it is with a single tooth. Do you

think that’s a reasonable approach for the average dentist?

DH: Absolutely. Not even for the average dentist — every

dentist. If we can deliver a restoration that is two to three

times stronger than anything else we can offer and it

doesn’t compromise esthetics, I think that’s definitely the

way to go. We’re looking at this material very seriously. I

mentioned that Ivoclar just introduced its IPS e.max Press

Impulse Value ingots. I did another case recently using

these V ingots — two cantilever bridges replacing laterals

off the canine and then eight other veneers — and it

was absolutely beautiful. I actually had the lab make two

sets: one IPS Empress and one IPS e.max. After trying in

both cases, I chose IPS e.max. Needless to say, we’re very

excited about this material.

MD: I agree, and dentists are certainly voting here at the

laboratory with their wallets, as well.

I remember one morning about a year ago, I opened a journal

and there was Dr. David Hornbrook doing a no-prep

veneer case! I wasn’t sure if this was a hostage situation in

which you had a gun to your head, but I was caught so off

guard that I spilled my coffee; I didn’t know what might have

prompted this. I have a feeling it’s material advancements.

And, of course, as somebody who performs such esthetic services

as yourself, the abuse of the no-prep veneer concept was

probably something that bothered you a little bit. But I really

thought it was a great sign. And you — being so open-minded

to go forward and try one of these cases, and then publish

the case! It was a gorgeous case, by the way.

DH: Well, thank you. I think prepless or very minimalprep

veneers are a technique that every dentist needs

to explore. Obviously, it’s public-driven because a major

dental manufacturer markets prepless veneers to the public,

so now patients are asking for this procedure. But I

think it’s been abused. We see very compromised results

with this technique more often than not. You work with

a dental laboratory, so you understand the importance of

the communication process. The communication between

the ceramist and the dentist is so crucial. I think a lot of

Interview with Dr. David Hornbrook35

dentists were, and still are, doing these prepless veneer

cases without really understanding the indications and

contraindications of this procedure, and we see some really

ugly and even unhealthy cases, especially tissue-wise.

I practice dentistry three to four days a week, and my

patients were asking about these prepless veneer cases.

And I really wanted to explore this more closely: Was it

the material itself, the lack of case planning or the technique?

So I went back and worked with laboratories and

materials and ideal cases. Together we established some

planning protocols that have yielded some surprisingly

unbelievable results, esthetically and functionally, with

prepless veneer cases. It’s an opportunity available for

patients and doctors. As I teach, I find that a lot of doctors

refuse to prep virgin enamel. This refusal limits their ability

to offer their patients some beautiful smiles. Prepless

veneer cases, when planned properly, are a viable alternative

to prepped veneers.

MD: That’s interesting. I’ve never heard a dentist say, I refuse

to prep virgin enamel. If somebody were to make that argument,

I would have to assume they were probably doing lots

of inlays and onlays. We certainly see lots of virgin enamel

on very healthy cusps being prepped in the name of insurance-approved

crown & bridge. I don’t know why they would

find it to be different just because it was in the anterior. You

know what I mean?

DH: I totally agree. But I hear and see it all the time. I see

dentists who will prep a full crown instead of an inlay. Or

they’ll prep virgin teeth on each side of a missing tooth to

place a 3-unit bridge, but they won’t do a 0.5 mm depth

cut on an anterior tooth. It amazes me.

MD: To me, no-prep veneers really are a great finishing

technique. I do hardly any no-prep cases where all eight or

10 units are no-prep veneers. But I do see cases where we

will replace, say, old PFMs on tooth #7 through tooth #10

with some IPS e.max crowns. And then I will place no-prep

veneers on the cuspids and the bicuspids and finish out the

whole smile without having to do any additional preparation.

That’s what I mean by a finishing technique: It is a

great way to finish out a smile when it’s done in conjunction

with other restorations.

DH: I agree, especially in this baby boomer age. A lot

of these people went through ortho as a teenager and

had their first bicuspids extracted. Now their posterior

quarters are collapsing and they want a nicer looking

anterior smile because of wear or discoloration. You

can do veneers, or you can replace existing crowns and

then place very conservative veneers on the premolars

and develop a beautiful smile.

MD: When I first learned about esthetic techniques in your

courses (back in 1995), we were doing fairly aggressive

preparations in the dentin when placing IPS Empress

veneers. And, as time has gone on, I have found that because

of improvements in ceramic materials, we can achieve similar

results with less reduction, assuming that the tooth is not

way out of an ideal arch form and it’s just an esthetic issue.

I like the idea of minimal-prep veneers, which, to me, is

something that has all the margins still in enamel. I like the

idea of bonding to enamel and keeping it intact. Do you

find that minimal-prep veneers, where you’re not necessarily

exposing dentin, are something that you are using more on

a day-to-day basis?

DH: When I first started teaching, around the time you

went through my courses, I think it was also the inexperienced

ceramist who established some of the “ideals” of

veneer preparation. IPS Empress was new to ceramists. It

was a monolithic material. They didn’t really understand

how to use the different opacities and translucencies in a

very thin environment. So they said, give us some more

room because we just don’t get it. And we would prep

0.7 mm to 1 mm, and they would want the contacts

broken. It was a new concept to them. We were teaching

very aggressive preps in the mid 1990s. In the last four

or five years, we’ve really done an about face. And what

we recommend now is 0.3 mm to 0.5 mm depth cuts,

assuming that the tooth is ideally positioned in the arch.

So, unlike in the past, when most of my preparation for a

veneer was in dentin, most of it’s now in enamel.

MD: Do you find that you enjoy bonding to enamel more

than dentin, or is it not a big issue for you? I hear from dentists,

whether it’s postoperative sensitivity or not being sure

how much they’re supposed to dry the tooth off, that they

really like the idea of etching enamel. Being able to dry it

to your heart’s content, see that nice frosty look. For those

of us who are kind of old-school dentists, it feels comfortable

in a sense. It’s something that we grew up with.

DH: Personally, I don’t really have a problem bonding

to dentin. We’ve been doing it for almost 15 years, and

I feel the predictability is there. But, I agree: I think that

dentists still struggle, even to this day, with this whole

total-etch and how wet is wet and how dry is dry concept.

Most clinicians feel a little more comfortable being able to

etch, rinse and dry as much as they want and get success.

I think we’re going to see increased predictability, less

standard deviation and less failure when the restoration

is primarily in enamel.

MD: I actually think that we’ll see more of these restorations

diagnosed. Obviously, there’s talk of over-diagnosis of

veneers, but I think that’s by a small percentage of dentistry.

Many dentists still don’t talk about this type of esthetic dentistry

because they’re not totally confident in their ability to

get a great non-sensitive result doing it completely on dentin.

They seem to like the idea of bonding to enamel, and

they know it works, and they get less post-op sensitivity. As a

36 www.chairsidemagazine.com

esult, they’re going to be more confident in their procedures.

DH: I agree with you.

MD: Speaking of total-etch versus self-etch, for your direct-placed restorations in

the posterior, are you using self-etch at all? Or are you still a total-etch guy?

DH: I’m definitely a total-etch guy! In fact, I’ve actually gone back to fourth

generation dentinal adhesive systems. So, I etch, and then utilize a separate

solution for the hydrophilic primer and a separate solution for the hydrophobic


MD: So you’re back to the regular two-bottle system. What are you using?

DH: I’m using ALL-BOND 3 ® (Bisco Inc; Schaumburg, Ill.). I like Bisco products

and respect Dr. Byoung Suh and the research being done at his company.

If I look back historically, what I would consider the gold standard would be

ALL-BOND 2 and OptiBond ® FL (Kerr Corporation; Orange, Calif.). And the

only problem, at least that I saw, primarily as an educator, was that ALL-BOND

2 was acetone-based, so it was a little more finicky. What Bisco did a few years

ago was change the hydrophilic carrier to alcohol. Now we have what I would

consider a new gold standard. It’s alcohol based, and you can use it for every

type of restoration you place in your office. Too many clinicians have too many

bonding agents in their refrigerator. Unless they can get an adequate amount

of light to polymerize the material, anything but a fourth-generation adhesive

will lead to a compromised result.

MD: It really is kind of funny. I don’t know how many times in dentistry we’ve seen

dentists take a step backward from what the latest and greatest is, with maybe the

exception of digital impressions, which tend to be more difficult and more timeconsuming

than conventional impressions. You look at the way things went to one

bottle and then all of a sudden we have self-etching in one bottle. It began to look

like, “Wait a minute. Are we doing this for us, are we doing this for the quality, or

are we doing this for our patients?” So it’s interesting to hear that you’ve gone back

to something that’s time tested and proven. It does take a little more time, but you

feel it’s better. I know you’re not going to go back to a self-cure composite instead of

light-cure composites or a belt-driven handpiece. You must really feel in your heart

that this is the right thing to do.

DH: I do. I have not seen the sensitivity that a lot of people saw with the

total-etch. Obviously, we’re isolating and controlling that surface moisture, not

over-etching the dentin. But it’s something where I have predictability; I have

success; I don’t have much postoperative sensitivity; I don’t see premature

failure; and I can look back and show you 15 years of clinical experience, as

well as excellent research.

The problem with today’s bonding agent chemistry is that it changes too fast.

You’ll see a study on a self-etching primer that bonds to enamel that was carried

out over a period of 36 months, and that material has changed chemistry

since the article came out. So we can’t look at these and say this is going to

have long-term success, where we can with total-etch systems.

I hear and see it all the

time. I see dentists who

will prep a full crown

instead of an inlay. Or

they’ll prep virgin teeth

on each side of a missing

tooth to place a 3-unit

bridge, but they won’t

do a 0.5 mm depth cut

on an anterior tooth.

It amazes me.

What we recommend

now is 0.3 mm to 0.5 mm

depth cuts, assuming

that the tooth is ideally

positioned in the arch.

So, unlike in the past,

when most of my preparation

for a veneer was in

dentin, most of it’s now

in enamel.

MD: Does this mean that you have not played with any of the self-etching flowable

composites yet?

DH: I’ve played with them, but I haven’t used them clinically except to alleviate

sensitivity in gingival abfraction lesions.

Interview with Dr. David Hornbrook37

MD: Yeah, I get it. If they work, it seems like a huge step forward for a dentist to be

able to place things this quickly. But you always have to ask yourself: Is this about

what’s convenient for me or is it about what’s better for the patient? And it may be

different in the hands of the average dentist than it is for you.

The problem with today’s

bonding agent chemistry

is that it changes too

fast. You’ll see a study

on a self-etching primer

that bonds to enamel

that was carried out over

a period of 36 months,

and that material has

changed chemistry since

the article came out. So

we can’t look at these

and say this is going to

have long-term success,

where we can with totaletch


DH: Again, I personally think the problem with some of the self-etching resins,

and even the resin cements, is that the manufacturer can show us this great

data, but what does it really do clinically in an environment on a live, vital

tooth? I won’t name names, but there’s a product that is highly touted by the

manufacturer as the best self-etching resin cement on the market. When zirconium

oxide first came out, we had a lot of failures because we were using the

wrong layering material, until it failed. So I cut off 45 zirconium oxide crowns

utilizing this cement that supposedly bonded excellently to dentin. And every

single one I cut off, the cement just peeled away in large sheets. There was

zero bond. So we have got to ask ourselves: Are the materials that show great

benchtop success on non-vital teeth done in a controlled environment giving

us the same clinical success in the mouth in a very hostile environment?

MD: Right. And there is always going to be a disconnect between the two. I

think you may be in second place behind me for the number of zirconia restorations

cut off. I know I’ve cut off more than that. Some of the zirconia crowns

I’ve cut off have actually been our new BruxZir ® material. BruxZir is a monolithic

zirconia restoration that, shockingly, dentists are prescribing in record

numbers. Believe it or not, BruxZir actually passed IPS e.max in sales volume

in November 2010. The ongoing wear studies at a couple of universities look

encouraging, but you can imagine, having cut off zirconia-based crowns, what it

might be like cutting off a full-contour zirconia crown! I have always thought this

is something we need to talk about a little bit more. In fact, I remember you calling

me once and saying, “Well, what if you have to do endo through one of these

zirconia-based crowns?” And, at the time, we didn’t have a good set of diamonds.

But now we’ve found some good diamonds to be able to cut those off. Are you

using many zirconia-based restorations right now in your day-to-day practice?

DH: Lithium disilicate has replaced my zirconium oxide-supported crowns in

the posterior. At one of my most recent lectures, a ceramist said IPS e.max has

destroyed his Lava (3M ESPE; St. Paul, Minn.) market, which makes sense!

I still use zirconium oxide-supported crowns for posterior bridges and three

units in the anterior. I do pride myself on trying to be metal-free as much as

possible, and that’s the only option I have. But single units, whether it be full

zirconium oxide or zirconium oxide-supported with layering ceramic, I rarely

ever do those. I do IPS e.max.

MD: If you look at the history of indirect restorations in dentistry, of course cast

gold was the first material out there — a monolithic material. Then, porcelain

jacket crowns, which left a lot to be desired in terms of strength, but it was still just

one material. Even back in the 1960s, there became this need to have something

that was more esthetic than gold. We can talk about the current esthetic desires

in Southern California, but even back in the 1960s there became a need to take a

metal coping and fuse it to porcelain.

The PFM has been the workhorse of dentistry for the last 40 years. It’s driven American

dentistry, this laboratory, and almost all laboratories, for that matter. But

PFMs have always suffered from the problem of having porcelain bonded onto the

metal substructure. And with this bilayered restoration, there is always a chance

that something can go wrong. In fact, it’s rather amazing that a lot of the times

nothing did go wrong with the bond between the two. But, by nature, a bilayered

restoration is going to have more problems than a monolithic restoration. I think

38 www.chairsidemagazine.com

we finally saw that with the ceramic-bonded-to-zirconia

market. Whether because of the coefficient of thermal expansion

or the way people were fusing the two parts in the oven,

there was going to be issues with compatibility and chipping.

So, we’ve seen the same thing: IPS e.max, a monolithic

material, and the monolithic BruxZir material introduced

after it have destroyed the zirconia market. Again, the

average dentist appears to be doing the same as you, at least

in that respect.

You’ve always struck me as a guy who would probably have a

CEREC ® (Sirona Dental Systems; Long Island, N.Y.) machine

in his practice. I’ve seen some of the artful direct composites

and killer temporaries you’ve done, and you’ve always work

with the best ceramists to get great results on your final restorations.

You really are as much of a lab tech as any GP I

know, but I don’t know that you ever fully embraced CEREC.

Do you have a unit now that I don’t know about?

DH: Actually, I do! But I’ve only had it for two weeks. I’ve

done only four crowns. I was waiting for the camera to

be better and for the software to be a little more intuitive

before I took the plunge. It has been worth the wait.

When the 3M ESPE Paradigm Block came out several

years ago, I was lecturing a lot on inlays and onlays. And

3M said: “Hey, we’ll send you a CEREC. Start doing the

Paradigm Block and when you love it, you’ll talk about

it.” Well, I hated the CEREC machine. It was so counterintuitive.

After three weeks, I sent it back and said, “I’m

not using this!”

MD: When was that?

DH: Maybe seven years ago? Whenever CEREC 3 came

out. But now I’m looking at the software and looking at

the camera, looking at the whole technology of digital

impressions (which is obviously the future of dentistry),

and it makes sense. You’re right in the fact that I do like

to play with ceramics, but I’m not nearly to the level of

expert ceramists. I can’t make a veneer or an anterior

crown look the way they can. But the fact is we’re using

monolithic IPS e.max in the posterior where I’m not

having to cutback or layer because I want strength. I’m

getting good esthetics with monolithic material. After all,

the lab was just waxing and pressing or milling it to full

contour and superficially staining it. I thought, why am I

not doing that?

MD: I wasn’t praising you so much for veneers; I was complimenting

your anterior direct temporaries. I would never

take an impression and send it to you and say, “Hey, make

my veneers.”

DH: I wouldn’t either!

MD: But I’ve seen what you can do on posterior teeth with

direct composite, and it did seem like you are the kind of

guy who would mill IPS e.max restorations in the posterior.

You’ve always offered such great services to your patients.

At Glidewell, we’ve now got six CEREC machines and probably

10 additional MC XL mills. I’ve got a CEREC AC in the

operatory and I am convinced — here I am practicing in a

lab, but regardless — I am convinced that one-appointment

dentistry is better than two-week dentistry.

DH: I’ve only done four of these, so I’m not great at it

yet. It’s like, how do I schedule it? One to two hours for a

single unit? How long is it going to take me? But for the

people who are great at it, I think it’s a huge advantage.

I see this technology as an advantage for even a three- or

four-day turnaround versus two weeks. Yes, we’re good

at making temporaries; that’s what we’ve always done,

and we’re good at it. But if we use this technology, we get

reduced lab costs, improved turnaround time (whether

that be 1.5 hours or three days) and total control.

Let me give you an example. On the third CEREC crown

that I did, an IPS e.max crown, I decided to try it in and

adjust occlusion in the blue block state before it was sintered.

And the patient bit down and broke the crown! In

the past, had I sent that crown to Glidewell and it was

IPS e.max or IPS Empress, I would have made a temporary,

sent it back, and you would have made me a new

one. Well, the cool thing about CEREC is that it was in my

library. All I had to do was go back to the library, click

it again, and in eight minutes I had a new crown! That’s

where there is a huge advantage. Or say you have a material

that you put in and there is a marginal discrepancy.

Instead of taking a new impression, you can take a new

digital impression and do it in three minutes.

MD: I agree. That’s a better way to say it. I mean, it’s true:

I do believe that one-appointment dentistry is better than

two-week dentistry. But I also believe that three- or four-day

dentistry is better than two-week dentistry. And I believe twoweek

dentistry is better than six-week dentistry! The shorter

period of time between prep and seat the better because of

bacterial leakage, teeth shifting and factors like that.

DH: And also the fact that today we are doing more conservative

dentistry. The primary complaint with some of

the crazy little single-cusp replacement onlays that we do

is, how do you keep temporaries in? It’s a pain! If you

plan to see this patient in three weeks, more than likely

you’re going to see them twice in the next three weeks

to re-cement the temporary. And if I can do it as either a

single visit or get it back in two or three days because I

milled it myself, we’re not going to have problems with


MD: Right, because patients don’t want to come in three

times. And, frankly, you’ve blown any profit you might have

made on that case after three visits.

Interview with Dr. David Hornbrook39

It’s funny you mention reduced lab costs because here at the

lab we are all for that. We want to reduce lab costs. I mean,

of course we'd like to work with more dentists, but primarily

we’d like to reduce lab costs. We’re getting ready to release,

most likely at the Chicago Dental Society Midwinter Meeting,

a digital impression system that we will sell to dentists for

their practice. We’re looking at it as an IPS e.max/BruxZir

wand, if you will. So, for monolithic restorations, a dentist

would take a digital impression, which we realize is more

work than a regular impression. To me, to take a digital

impression if it’s not hooked to a mill is kind of silly, unless

it’s going to save you money. And some of the other digital

impression systems actually cost you money. It’s very difficult

for you to get any ROI with those systems.

With the Glidewell system, we’re talking about taking a digital

impression and sending it to the lab. Submitting the digital

impression this way saves the dentist $27 on the cost of the

restoration. There is no one-way shipping cost ($7 savings),

no cost for impression material ($10 savings), and the lab

discounts $10 because it can be digitally fabricated. So, we

do want to reduce lab costs to dentists by cutting out some of

the steps by making these model-free crowns.

You and other CEREC users have proven that model-free

crowns can be made, and Sirona has 25 years of experience

doing it. We know it works. Have you used many of the other

digital impression systems, such as Cadent iTero (The Cadent

Company; Carlstadt, N.J.) or Lava C.O.S.?

DH: I haven’t used Cadent clinically. I’ve played with it

chairside and it seems like one of the easier systems to

use. I know a lot of laboratories prefer it. And I like the

technology of the Lava C.O.S. system, but it’s very time

consuming. We looked at it, we were going to buy it, and

then we decided not to. As we talked to colleagues, some

of my friends that are excellent dentists, a lot of them

had sent it back. It’s not that it wasn’t accurate or that its

technology wasn’t cool. But if it takes 40 minutes to take

an impression, it’s not profitable.

You mentioned the cost savings of shipping, and that’s

something that a lot of dentists don’t look at. If they say,

oh, I only save $10 by doing that, what they don’t take

into account is the money saved in outgoing shipping.

They will also get a better turnaround time because instead

of taking two and a half days to get it to you, the

case arrives at the lab instantly.

MD: Exactly. I don’t like it when dentists are kind of force-fed

technology or when dentists are told they are not doing great

dentistry if they’re not using this technology. For example: On

your polyvinylsiloxane impressions, do you perceive that you

have a big problem with them day in and day out?

DH: Not a major problem, but I think that if you really

looked at the weakest link in the chain of restorative

dentistry, it would be the impression and the pour-up in

crummy dental stones. But is that going to keep my restorations

from lasting 10 years or more? No. We have more

accurate materials today than we did 20 years ago, when

dentists were doing gold crowns that were in the mouth

for 40 years. So, I totally agree with you on that.

MD: That’s why I feel that if the digital impression system

is not tied to a mill, where you can do same-day dentistry

or three- or four-day dentistry and save nearly $20 per IPS

e.max crown through a lab, what’s the point of going through

the extra effort to do something like this?

What are you using for a diode laser these days? And I’m

guessing you have a hard-tissue laser, as well?

DH: I use a diode every single day in my practice; we

have one in each operatory. As far as hygiene, I personally

think that use of a laser is standard of care. Dentistry

as a whole will realize that in a few years.

The advantages of present-day diodes compared to the

ones we used are that they are affordable and smaller.

You can get a good laser for less than $5,000; all of a sudden,

lasers are very affordable.

We’re also doing closed-flap osseous using an Erbium:YAG

laser (AMD LASERS, LLC; Indianapolis, Ind.), which is

very cool. So we’re performing crown lengthening without

laying a flap, and we’re getting unbelievable results.

Lasers, just like digital technology, are going to change

the way we practice dentistry as they become more

affordable and more dentists adopt the technology.

MD: Do you feel pretty confident with closed-flap crown

lengthening? I know it drives some periodontists crazy — it’s

hard to treat what you can’t see. But I have to say that biologic

width violations are a real problem. As you walk through the

laboratory and look at anterior models, you see interproximal

violations left and right. You know the crowns probably

look pretty good, but the tissue is purple interproximally

because the prep outline doesn’t follow the gingival outline.

Are you doing most of these in the anterior or posterior?

DH: I do it just in the anterior because I can tactfully feel

the bone and make sure I’m not troughing or creating an

artificial biologic width. Because posterior bone is thicker,

I don’t do it. I refer that out if it needs to be done. I

was keeping track of repercussions up to 2,500 teeth, and

then I stopped, but we’ve had zero repercussions. I’ve

done it in all my courses since 2004, and we’ve seen no

problems. The cool thing is that unlike traditional crown

lengthening, where a flap is laid and a diamond bur is

used on the bone and then you wait 12 to 16 weeks,

we’re prepping and impressing and provisionalizing on

the same day that we do our osseous. We’re doing some

fun, really cool things with that.

40 www.chairsidemagazine.com

MD: Maybe in a perfect world every patient would be flapped and you’d see directly

what you were doing. But the reality is that most of these cases have biologic

width violations and dentists aren’t doing anything. They’re taking the old crown

off and putting a new crown on. If anything, the margin gets dropped just a little

bit further as the doctor goes in and cleans the cement off the prep, so the biologic

width violation gets a little bit worse. I think you’re seeing good results because it’s

a step in the right direction. It may not be 100 percent perfect, but maybe the patient

wouldn’t have had it done surgically anyway. I think that some treatment to

improve biologic width is better than no treatment at all.

DH: That’s right.

MD: You mentioned that you do closed-flap crown lengthening procedures during

your courses. Tell me a little about the courses that you’re putting on today.

DH: The best source for those who are interested in where I’m going to be as

far as a lecture or hands-on course is to visit www.davidhornbrook.com. Click

on “Calendar,” and it will go through the things we’re doing. I still do a lot of

full-day lectures across the country, and that’s actually ramped up because of

all the new materials. People are obviously not getting trained in dental school

on IPS e.max, prepless veneers and lasers. Now they’re hearing about it and

getting excited. It’s good for me because I’m getting out there more, and I enjoy

that aspect of my career.

We are still doing some live patient courses. As you mentioned, you went to

my esthetic courses when I was teaching at LVI. Then I formed P.A.C.~live

and the Hornbrook Group, which were also live-patient, hands-on treatment

courses. Now we’re doing it through a series called Clinical Mastery. Doctors

can go to www.clinicalmastery.com and see a list of the courses we’re offering,

including occlusion courses and full-mouth and anterior live patient courses,

in which dentists will bring their patients and their team.

We’re doing these courses primarily in Mesa, Ariz., at the new dental school

A.T. Still University – Arizona School of Dentistry and Oral Health (ATSU).

This is just a phenomenal dental school. It’s so different from where I went to

dental school. The faculty is very embracing, very technologically advanced.

In fact, I was talking to the school’s dean, Dr. Jack Dillenberg, and the school’s

recommendation for posterior restorations is composite, not amalgam. The

school only teaches amalgam so its students can get through the boards. It’s

very interesting how different it is. The faculty is teaching veneers, implant

placement, lasers. Students actually go through an entire laser curriculum. The

students are learning some very cool things.

MD: That’s a real education! That’s pretty impressive.

DH: It’s not that I’m pushing this particular school, but if a doctor who reads

this has children, relatives or friends who are thinking about going to dental

school, I would look at ATSU. They only have one specialty program in the

school — orthodontics — which means that graduating seniors leave dental

school having placed an average of 15 to 20 implants because there is no

periodontal program. The students are doing perio full-mouth surgery and

impacted wisdom teeth — they’re just doing some really cool things.

If you really looked

at the weakest link in

the chain of restorative

dentistry, it would be the

impression and the pourup

in crummy dental

stones. But is that going

to keep my restorations

from lasting 10 years or

more? No. We have more

accurate materials today

than we did 20 years ago,

when dentists were doing

gold crowns that were in

the mouth for 40 years.

MD: The better part of having no specialty programs is that there are no specialists

there to tell them that this stuff is too difficult for them to do, and they probably

shouldn’t try it. That was my dental school!

DH: Exactly, same with me. So we’re doing some cool things at ATSU. Again,

Interview with Dr. David Hornbrook41

dentists can find out more about those courses by visiting my website

www.davidhornbrook.com or www.clinicalmastery.com.

MD: I want to close by telling you a story. I’m not sure if I’ve told you this before,

but when we were together at LVI, I brought a patient …

DH: I remember the case! When you left retraction cord in there?

MD: Whoa, whoa, whoa, I didn’t leave retraction cord in there. What happened

was that the two IPS Empress crowns on tooth #8 and #9 were deeply subgingival.

We weren’t doing much soft tissue recontouring back then, and certainly no hard

tissue. But that’s really what this case needed. You said, “Let’s put some retraction

cord in to contain the gingival fluids when we bond these crowns into place.” Well,

I guess I was a little sloppy. I pulled the retraction cord out from tooth #8 after curing

the cement, but when I went to pull out the retraction cord on tooth #9, I had

bonded it into place. I tried to get it out and you tried to get it out. The good news

is that it was size 00. The bad news is that it was black, and I’d bonded it between

the crown and the tooth. You could see it through the patient’s thin tissue, and

you said to me, “Congratulations. You are the first dentist in history to do an allceramic

crown that has a gray margin like a PFM.” I’ve always been proud of that.

Later, that patient went snow skiing with his wife and she fell getting off the lift and

smacked him in the face with a ski pole. And he called me in a panic and said,

“My wife broke one of my front crowns off.” I asked which one and he answered,

The one on the left (tooth #9).” I thought to myself, Hallelujah! Then he asked if he

should look for it. “Hell no!” I didn’t want to have to explain what the black string

was hanging off the crown.

So, your course and that experience were really instrumental in teaching me to pay

attention and really do things right. Dentistry has been a learning experience for

me, with this average set of hands I have.

David, I want to thank you for being there every step of the way and being very

generous with your time, especially for an interview like this.

DH: Thank you, Mike! It’s always great to hear your voice because I haven’t

talked to you in so long. You certainly have done so much for our profession,

and I consider you a mentor, a great friend, and I appreciate being asked. CM

Dr. David Hornbrook is a leading educator in esthetic dentistry. For information on his upcoming lectures and

hands-on courses, visit www.davidhornbrook.com or www.clinicalmastery.com.

42 www.chairsidemagazine.com




– Article and Clinical Photos by

Ellis J. Neiburger, DDS and

Yehonatan L. Frandzel, FPH

46 www.chairsidemagazine.com

A digital photo or radiograph may show a virtual

reality that is considerably different than actual

reality. Therefore, there is a need for the practitioner

to know how to detect virtual images and

distinguish them from reality.

Recent developments in digital imaging in dentistry and

easy-to-use editing software present many occasions for

altering or fraudulently changing digital images of products,

patients and their dental conditions, treatments and

radiographs. Though seemingly impossible to detect when

carefully done, there are numerous clues of digital editing

that can be detected by the observant practitioner.


In the last few years, more dentists and publications have

increasingly switched from standard film photography

and radiography to computer-generated digital techniques.

1–4 Digital photography (DP) and digital radiography

(DR) are produced by an electronic sensor linked to

a computer, which generates and manipulates the virtual

image either by light or X-ray exposure. Sophisticated

editing software can magnify, shade, duplicate and

infinitely change the image. 1–4

Image modification is not new. Since the 1870s, images

on photographic film have been manipulated to show desired,

artificial changes. 5,6 The creation of “spirit images,”

burning, dodging, airbrushing, cropping, reverse printing

and adding new subjects (e.g., a filled endodontic

canal or whiter teeth) on an existing photo image has

always been possible with photographic film. The famous

disappearances of “vanishing commissars” in photos from

Stalinist Russia, fantasy motion pictures (e.g., “Titanic” or

“Harry Potter”), TV shows and the “retouched” photos of

the many tabloid newspapers are prime examples. 4–6

Until recently, these changes were technologically demanding

and expensive to do. 6 Often they were done

poorly, showing obvious signs of manipulation. However,

with the advent of DP, DR and inexpensive, easy-to-use

editing software, quality changes are as simple and inexpensive

to achieve as pressing a computer key or pointing

a mouse. 4–6 Most photographers and publications will

use editing software to “clean up” images: from cropping

and eliminating red eye in portraits to repositioning the

Egyptian pyramids (National Geographic) in order to fit

the page better. 5 Many dentists and dental publications

do the same.

Today, a digital photo or radiograph may show a virtual

(false) reality that is considerably different than actual

reality. Therefore, there is a need for the practitioner to

know how to detect virtual (computer-generated) images

and distinguish them from reality. 7 The quality of treatment

and research, the descriptions of commercial products

and the desire for honest cosmetic predictions for

our patients depend on these skills.

Detecting Computer-Enhanced Dentistry47

What Digital Photography

Can Do

Figures 1, 1f: Computer-generated extraction of deciduous tooth and creation of two restorations

Figures 2, 2f: Virtual endodontics, periapical healing and four restorations

Figures 3, 3f: Computer-created crown and three carious lesions (molars)

Popular software such as Adobe ®

Photoshop ® (San Jose, Calif.), Corel ®

PaintShop Photo ® Pro (Mountain

View, Calif.), Apple iPhoto (Cupertino,

Calif.), Google Picasa 3 (Mountain

View, Calif.), and hundreds of

bundled digital camera photo programs

have found their way into

many offices and homes. 6 If one

buys a digital camera, it most likely

comes with a functional editing program

that allows the manipulation of

photos. Using these programs, one

can cut, paste, erase, combine, overlay,

reshade and otherwise retouch

any photo taken. Patient photos can

be enhanced to show better-shaped,

positioned or whiter teeth and then

used as a marketing tool or prognostic

inducement for additional treatment.


Alternately, this means one can also

create decay, cracks and abscesses on

DR images of normal teeth in order

to mislead other professionals, thirdparty

payers and the courts. 1–4,7,8

DP and DR software allows the operator

to change the presence, shade,

color saturation, brightness and contrast

of bone or tooth structure in a

digital image. 4–6 Restorations, teeth

and pathology can be virtually created,

removed or modified in the

digital image. In some cases, this

activity may approach the level of

fraud, where images of restorations

or treatments (e.g., endodontics or

extractions) can be created by computer

and submitted as evidence in

trials or sent to third-party payers as

proof of actual diseased conditions

or previously billed treatments. 1–4,7

Figures 4, 4f: Virtual removal of root, bone healing and creation of a 3-unit fixed bridge

Virtual Examples

Figures 1–6 are digital images of actual

radiographs. Figures 1f–6f are

corresponding digital images that

have been edited to show pathologic

changes, healing and restorations

that have not actually occurred. They

48 www.chairsidemagazine.com

are computer simulations.

Figure 1f shows computer enhancements

to Figure 1 where a tooth has

been virtually extracted, the bone of

the extraction socket partially healed

and two virtual restorations placed.

Note the root fragment left in Figure

1f’s extraction.

Figure 2f shows a re-edited Figure 2

where virtual endodontic treatment

was performed, the periapical radiolucency

partially healed (smaller

size) and four restorations placed.

Nothing was really done except for

computer simulations.

Figure 3 shows distal decay in the

upper second premolar and no other

decay. Figure 3f demonstrates a virtual

crown that “restored” distal caries

in the upper second premolar;

also note the virtual decay on the

upper second (distal) and third (mesial)

molars and mesial decay on the

lower second molar.

Figure 4f presents virtual treatment

of Figure 4 where a root appears to

have been extracted, partial healing

of the socket accomplished and a

3-unit fixed bridge made — all within

a few minutes of computer work.

Figure 5f shows the addition of an

extra endodontic filling and crown

on the first bicuspid of the perfectly

natural tooth in Figure 5.

Figure 6f shows whiter teeth than

what actually appears in Figure 6.

This can be used as proof of the

power of “Virtual Product X,” which

bleached the patient’s teeth in a few

seconds — except the active ingredient

came from the computer.

How to Detect Computer-

Enhanced Images

Sophisticated photos of dental products

and techniques are appearing in

dental literature in the form of advertisements

or research treatment

results. Many of these images are

computer-generated and retouched.

Figures 5, 5f: Computer-generated endodontics and crown on first premolar

Figures 6, 6f: Virtual tooth whitening

Sophisticated photos of dental

products and techniques are

appearing in dental literature in the

form of advertisements or research

treatment results. Many of these

images are computer-generated

and retouched.

Detecting Computer-Enhanced Dentistry49

If it looks too good to be true, it probably is. Wild

claims that defy your own experience can indicate

potential computer editing. Perfect margins, shading,

alveolar bone regrowth and other signs of perfection

should raise questions.

The discriminating practitioner must be able to identify

the virtual from the real so that he or she can view the

material presented on a sound, accurate scientific basis,

rather than a virtual basis. There are a number of classic

techniques one can use to detect computer enhancements

in digitally produced photos and radiographs.

If it looks too good to be true, it probably is. Wild

claims (supported by impressive photos) that defy

your own experience can indicate potential computer

editing. Perfect margins, shading, alveolar bone

regrowth and other signs of perfection should raise

questions. Whether it is seen in a lecture on clinical

dentistry or in a magazine or journal touting whitening,

etc., one must be cautious. In the real world,

nothing is perfect. Any photo that is becomes suspect.


Computers are made to make straight lines and perfect

angles. This seldom occurs in real life and is

a dead giveaway for deception. The straight edges

and perfect angle of the virtual molar mesial occlusal

restoration in Figure 1f is a very good example.

Compare the irregular shape of real restorations in

Figure 3 with the straight, even artifacts in

Figure 1f. The four virtual restorations in Figure 2f

are another example. They are too perfectly rounded

and of similar size and shape — a rarity in real life.

Close examination of the margin of the virtual crown

in Figure 3f reveals a jagged border. This is an unrealistic

attempt to eliminate a straight line, and thus

detection that the image has been modified. 2,5,6

Many digitally enhanced DR restorations appear as

one solid color. Most natural restorations will show

various degrees of radiopaqueness (density), as the

restoration becomes thinner or thicker when placed

on or in a real tooth. Actual restorations are seldom

all one color or shade. Compare the real crown in

Figure 5 or the restorations in Figure 3 to the restoration

images of Figures 1f, 2f and 3f. There are

subtle differences in each real restoration’s peripheral


Look for “Frankenstein” images where, in many

photos, the head of a subject appears to be stitched

onto the body or a virtual tooth is inserted into a jaw.

Changes in shading, angles and seams can identify

this kind of manipulation. Relative uniform lighting

requires that shadows appear in the same direction

and on all areas of the photo. If they do not, then

editing should be suspect. Look at the reflections

of light on the skin of the patient in Figure 6 as

compared to virtual Figure 6f. In Figure 6f, there are

more highlights on the skin around the lips, indicating

that the shade of the entire photo was lightened

in order to make the teeth appear whiter. 1–8

Look for imperfections in geometry and whether

the vanishing point is “off.” Check if the quality of

the image is the same throughout the photo. If it is

not, then something may have been added. Look for

reoccurring patterns and objects, as well as discontinuities

in the background. A lazy image editor may

use standard shapes to fake restorations rather than

spend the time to draw each restoration individually.

Figure 2f shows virtual restorations of similar size

and perfect shape. These were digitally enhanced. 5,6

Often, enhancements to images can become apparent

if you use “false color image” editing. Radically

changing the contrast and brightness can also be telltale

signs. Using your computer to radically change

the colors (false coloring) of the suspected photo

will serve to identify otherwise subtle changes. This

process can be done in just a few seconds with most

photo editing software. 5–8

Look for artifacts of the editing process. These may

include tracks, brush marks, cavities and unnatural

compression. Rough texture transitions and uneven

pixilation (the small dots that make up the image)

across the image is strong evidence of editing. 6

50 www.chairsidemagazine.com

Look at the reflections of light on the skin of the patient

in Figure 6 as compared to virtual Figure 6F. In Figure

6F, there are more highlights on the skin around the

lips, indicating that the shade of the entire photo was

lightened in order to make the teeth appear whiter.

Experienced image editors can detect metadata, short

digital fingerprints formed on every digital image. In

addition to storing information on the exact date of

creation and the modification of a file, metadata can

link the photo to the camera used, ownership (e.g.,

watermarking) and a variety of manipulations that

may have been used to modify the raw image. Unfortunately,

an image editor bent on deception can

remove this data and thus play an infinite cat-andmouse

game of detecting and hiding or scrubbing

evidence of image manipulation. Unless you wish

to spend considerable sums of time and money for

this service, this level of detective work is seldom

practical in dentistry. 5,6,8

Look at the size (megabytes) of the image file. Enhanced

images will have a considerably larger file

size than those that have no changes.


1. Calberson F, Hommez G, DeMoor R. Fraudulent use of digital radiographs.

Rev Belge Med Dent. 2005;60(1):58–67.

2. Guneri P, Akdeniz B. Fraudulent management of digital endodontic images.

Int Endod J. 2004;37(3):214–20.

3. Boscolo F, et al. Fraudulent use of radiographic images. J Forensic Odontostomatol.


4. Wadkins P. Digital radiographs. JADA. 2000;131(1):18,20.

5. Henshall J. Beware false reality. Photographer. 1998 Feb:28–30.

6. Casimiro S. Seeing is not believing. Popular Science. 2005 Oct:71–79.

7. Tsang A, Sweet D, Wood R. Potential for fraudulent use of digital radiography.

JADA. 1999;130(9):1325–29.

8. Gaylord C. Digital detectives discern Photoshop fakery. Christian Sci Monitor.

2007 Aug 29. Accessed 15 Dec 2007.

Reprinted with permission from the Journal of the Massachusetts Dental

Society, Vol. 57/No. 2, Summer 2008.


Because digital imaging has become so popular in dentistry,

images of photos and radiographs may be edited

to show different conditions than what is seen in reality.

Photos can be enhanced to show whiter and straighter

teeth, smoother skin or a well-blended margin on a

crown. Digital radiographs can be changed to show additional

pathology or treatment. There are numerous signs

of this manipulation, which an informed practitioner can

detect. CM


The authors wish to thank Andent Inc. for permission to

republish the photos in this article.

Dr. Ellis Neiburger is a general practitioner in Waukegan, Ill. Contact him at

847-244-0292 or eneiburger@comcast.net.

Yehonatan Frandzel is a forensic photography consultant based in Haifa, Israel.

Detecting Computer-Enhanced Dentistry51

Periodontal Photo Essay:

Is Closed-Flap Crown Lengthening

a Biologically Sound Procedure?

– ARTICLE and CLINICAL PHOTOS by Daniel J. Melker, DDS


The objective of this article is to discuss the biological aspects of bone and the changes that occur when it is infringed

upon either through disease or during the correction of certain periodontal conditions. It will discuss the correction of

osseous defects and why these procedures are necessary to create a long-term stable environment. When a comparison

is made between certain periodontal problems stemming from either biologic width invasion or periodontal disease

with closed-flap crown lengthening, similarities suggest that closed-flap crown lengthening is an unsound biologic


Periodontal Photo Essay53

Case 1

Figure 1

Figure 2

Figure 1: In order to change the length of the clinical crowns for

a new restorative commitment, crown lengthening was advised.

When doing closed-flap crown lengthening, marks are made on

the laser tip to determine the amount of bone that needs to be

removed to create space for a new crown. Soft tissue can also

be removed when necessary. The major problem with such a procedure

is the inability to remove the troughs created by the vertical

removal of bone.

Figure 2: The restorative doctor and periodontist discussed

the case and determined that 1 mm of length would be needed

on the incisal edges. An appropriate formula was used for the

surgical procedure: biologic width, approximately 3 mm; clinical

crown length, 10 mm; added porcelain, 1 mm. The total length

needed from the existing incisal edge to the bone = 13 mm.

Note: Six weeks postoperatively, it will be determined if touchup

surgery will be necessary to correct any biologic changes.

Figure 3: During crown lengthening, troughs in the bone occur that

are similar to the periodontal vertical defects caused by endotoxins

released by bacteria. Notice the significant defect caused between

tooth #7 and #8; this is unavoidable.

Figure 3

54 www.chairsidemagazine.com

Case 1

Figure 4 Figure 5

Figure 4: A probe reveals the trough created in the bone due to

crown lengthening. The probe shows the vertical defect involving

line angles caused by the crown lengthening. The thicker the bone,

which is common in the interproximal, the greater the resulting defect.

Herein lies the problem with closed-flap crown lengthening:

Without the ability to remove the troughs created by lengthening

the teeth, serious long-term consequences can occur due to the

lack of uniformity between bone and soft tissue. It is critical for

bone to mimic soft tissue when contouring. The surgeon must

create a parabolic architecture. Note: Horizontal access and

visibility are necessary to remove the troughing caused by

crown lengthening.

Figure 5: Crown lengthening is completed on tooth #7 and #8.

Figure 6: Notice how the bone and soft tissue mimic each other.

The existing length of tooth #8 and #9 is now 13 mm from the bone

to the incisal edge. This allows for 3 mm of biologic width and

10 mm for the clinical crown, with the new crown adding 1 mm to

the incisal edge.

Figure 6

Periodontal Photo Essay55

Case 1

Figure 7 Figure 8

Figure 7: The tissue is sutured into place using a 5-0 chromic gut.

Referring back to the original discussion on biologic width and

clinical crown length, the tissue is placed where the remaining tooth

structure is 10 mm. Notice there is an abundance of connective

tissue remaining. Without the ability to remove the troughing created

by the vertical removal of bone, the author finds closed-flap crown

lengthening to be biologically unsound. Horizontal access and

visibility are needed to create a sound biologic surgical procedure.

Figure 8: Day of impression. Notice the tissue is slightly red. Due to

her teaching schedule, the patient could not accommodate normal

postoperative appointments. (The author and case surgeon would

have preferred to see her several weeks before her impressions

to reduce any inflammation, as this is the doctor’s responsibility.

Subgingival chlorhexidine would be used to reduce minor inflammation.)

Figure 9: Final restorations with mild gingival irritation. Over time,

the author expects the tissue to improve, although reducing inflammation

prior to impression taking is the preferred method.

Figure 9

56 www.chairsidemagazine.com

Case 2

Figure 1

Figure 2

In this case, you will notice that the defect, which is

caused by biologic width invasion, mimics the defect

caused by closed-flap crown lengthening in the first

case. Both are biologically unsound.

Figure 1: Below tooth #5, the existing crown is violating the biologic


Figure 2: Reflection of a flap exposes a created defect on the

buccal of tooth #5, where biologic width invasion has occurred. To

correct the defect, horizontal removal of bone is necessary, as well

as the creation of bone architecture that mimics the soft tissue.

Figure 3: This shows the ideal osseous and soft tissue architecture

after proper bone contouring to remove the troughs. The crown is

violating the biologic width. This crown will be removed and a core

and a provisional will be placed.

Figure 3

Periodontal Photo Essay57

Case 3

Figure 1

Figure 2

Figure 1: Crown lengthening is necessary to create a space for

the biologic width. The author believes that visibility is critical for

properly treating bone. A flap is required to see the underlying

structures for crown lengthening.

Figure 2: Regardless of the instrument — bur or laser — used when

crown lengthening is performed, bone is removed. Unless the tip

of the bur or laser is exactly the same dimensions as the bone to

be removed, a trough will be created when there is a greater thickness

of bone than tip diameter. This is a biologically unsound result.

The bur is left in place to show the crater that is created as the

bone is removed.

Figure 3: Using the bur or laser horizontally allows the crater to be

removed and an ideal osseous architecture to be created. Notice

that the bone and soft tissue mimic each other.

Figure 3

58 www.chairsidemagazine.com

Case 4

Figure 1

Figure 2

Figure 1: The existing crown on tooth #28 violates the biologic

width. There are periodontists who say that if the biologic width is

invaded, the bone will remodel to accommodate the infringement

on this area. In 35 years of treating biologic width invasion, the

author has consistently seen osseous defects associated with such

violations. No remodeling is noted.

Figure 2: Upon reflection of the tissue, a cratered defect is noted,

presumably associated with the biologic width invasion. This type

of defect must be removed to create an environment for the bone

and soft tissue to closely adapt for minimal probing depth.

Figure 3: The defect is removed and the osseous support will now

conform to the parabolic architecture of the soft tissue as it heals.

Thus, the bone mimics the soft tissue and minimal pocket depth

will be present upon complete healing.

Figure 3

Periodontal Photo Essay59

Case 5

Figure 1 Figure 2

Figure 1: With the tissue reflected, the ravages of periodontal

disease on the bone can be seen clearly. A reverse architecture

is visible. This means that rather than the bone conforming to

the contours of the tissue, it is irregularly shaped, thus causing a

discrepancy between the soft tissue and the bone, resulting in a

periodontal pocket.

Figure 2: After osseous contouring to remove the pocket in the

bone, the present configuration will mimic the soft tissue upon

healing. A minimal probing depth will remain, allowing for better

long-term maintenance.


Without the ability to remove the troughing created by the vertical removal of bone, closed-flap crown lengthening is

biologically unsound. Horizontal access and visibility are needed to create a sound biologic surgical procedure. CM

Dr. Daniel Melker is in private practice in Clearwater, Fla., and lectures nationwide. Contact him at 727-725-0100.

60 www.chairsidemagazine.com

Patient Product Review

Dr. DiTolla’s

In my experience, men love toothpicks. It has also been my experience that men don’t floss. Traditionally, dental

professionals have been conditioned to persuade male patients to routinely floss. (Ask your hygienist how this educational

approach is going, if you aren’t sure.)

I instead prefer to give men a tool they will use regularly, even if it isn’t as effective as flossing: the toothpick. Wooden

toothpicks, which are freely available in all restaurants, have some limitations that make them a less than ideal choice

for routine use. However, Opalpix toothpicks by Ultradent are flat and tapered to allow good interproximal access with

minimal trauma to the papilla. I’ve seen patients do a pretty good job of getting them under fixed bridgework, as well.

It’s a great option for the floss-phobic men (read: all men) who come to your practice. CM

Opalpix is a trademark of Ultradent Products Inc. To purchase this product, contact your local dental dealer or visit https://store.ultradent.com.

Dr. DiTolla's Patient Product Review63

The Chairside® PHOT Hunt

How many differences between

the two pictures can you find?

Circle the differences on the version

labeled NEW below. Then,

write down how many differences

you found, tear out this whole

page and send it to:

Glidewell Laboratories

ATTN: Chairside magazine

4141 MacArthur Blvd.

Newport Beach, CA 92660

Or scan your entry and e-mail it to


One entry per office. Participation

grants Chairside magazine permission

to print your name in a future

issue or on its website.

The winner of the Vol. 6, Issue 1,

Chairside Photo Hunt Contest will

receive $500 in Glidewell credit

or a $500 credit toward his or

her account. The second- and

third-place winners will each receive

$100 in Glidewell credit or a

$100 credit toward their accounts.


Entries must be received by

March 31, 2011. The winners will

be announced in the spring issue

of Chairside magazine.




City/State of Practice



Total Found:___________________

64 www.chairsidemagazine.com


“With the current price of gold,

dentists have begun mining.”

Jeri Coffey, DDS

Riverside, Ill.

1st place winner of $500 lab credit

“No, he doesn’t need crown

lengthening. It’s only 12 mm


Stephen L. Kirkpatrick, DDS, PLLC

Olympia, Wash.

2nd place winner of $100 lab credit

“That’s not the nerve …

It’s a Chilean miner!”

Gregory L. Jovanelly, DMD

Aliquippa, Pa.

3rd place winner of $100 lab credit

Honorable Mention

These OSHA requirements are getting more strict every day!”

Ernest Johnson, DDS

Phoenix, Ariz.

“No, but I did stay at a Holiday Inn Express last night.”

James Tagliarini, DMD

Danbury, Conn.

The Chairside ®

Caption Contest Winners!

Congratulations to Drs. Jeri Coffey, Stephen Kirkpatrick and Gregory Jovanelly, winners of the Vol. 5, Issue 4, Chairside Caption Contest.

The winning captions were chosen from hundreds of entries e-mailed and submitted online to Chairside magazine when readers were

asked to caption the above photo. Entries were judged on humor and ingenuity.

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