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Inclusive®

Restorative Driven Implant Solutions Vol. 2, Issue 4

A Multimedia Publication of Glidewell Laboratories • www.inclusivemagazine.com

From Intraoral Scan

to Final Custom

Implant Restoration

Dr. Perry Jones

Page 6

Lab Corner: Accurately Seating

Inclusive Custom Abutments

Dzevad Ceranic, CDT

Page 28

Delivering a Mini Implant

Overdenture

Dr. Christopher Travis

Page 36

Mapping the Mandibular

Canal with CBCT

Dr. James Jesse

Page 46

Esthetics and Optical

Properties of Zirconia

Research Scientist Ken Knapp

Page 50

Implant Q&A:

Dr. Michael McCracken

Page 15


On the Web

Here’s a sneak peek at additional Inclusive

magazine content available online.

ONLINE Video Presentations

• Dr. Perry Jones demonstrates the all-digital restoration of an anterior

case, from intraoral scanning to the CAD/CAM fabrication of

all-zirconia custom abutments and a monolithic zirconia bridge.

• Dr. Michael McCracken discusses the ability of dental implants

to counteract bone resorption, as well as the various restorative

options available today.

• Dr. Christopher Travis outlines the proper procedure for delivering

a newly fabricated mandibular overdenture retained by four

mini implants.

• Research scientist Ken Knapp explores the optical properties

of partially stabilized zirconia and its future as a leading dental

restorative material.

Check out the latest issue of Inclusive

magazine online or via your smartphone at

www.inclusivemagazine.com.

ONLINE CE credit

• Get free CE credit for the material in this issue with each test you

complete and pass. To get started, visit our website and look for

the articles marked with “CE.”

Look for these icons on the pages that follow for

additional content available on our website,

www.inclusivemagazine.com.

– www.inclusivemagazine.com –


Contents

6

15

From Intraoral Scan to Custom Implant Restoration

Digital technology continues to revolutionize modern dentistry,

benefitting every phase of treatment from diagnosis to final restoration.

Here, Dr. Perry Jones demonstrates the use of an intraoral optical

scanning system, followed by the CAD/CAM design and milling

of all-zirconia custom abutments and a monolithic zirconia bridge,

to precisely restore a historically problematic anterior case.

Implant Q&A: Interview with Dr. Michael McCracken

Ongoing studies have revealed correlations between tooth loss and

systemic health issues such as gastrointestinal disorders, atherosclerosis,

or even cancer. In this interview, prosthodontist and University

of Alabama School of Dentistry professor Dr. Michael McCracken

discusses the use of dental implants to stave off resorption, access to

treatment, and various restorative options available today.

ALSO IN THIS ISSUE

21 Optimizing the Design of Zirconia

Implant Abutments: A Finite Element

Analysis

28 Lab Corner: Accurately Seating

Inclusive ® Custom Abutments Using

an Acrylic Jig

36

46

50

Delivery of a Mini Implant-Retained Overdenture

Though mini implants are designed to accommodate the immediate

loading of an existing denture in the presence of primary stability,

patients are often better served by the fabrication of a prosthesis

specifically fitted for the new biologic form factor. Dr. Christopher

Travis outlines the process of providing a new overdenture designed

for optimal function and esthetics following the osseointegration of

four mini implants.

Implant and Mandibular Canal Mapping

Three-dimensional CBCT images have a wide range of diagnostic

and treatment planning uses, and are quickly becoming a standardof-care

practice in implant planning. Using an illustrative case report,

Dr. James Jesse describes how the latest 3-D imaging technology can

help to produce safer, more predictable treatment outcomes.

Zirconia Crown Esthetics and Optical Properties

With their flexural strength, fracture toughness and toothlike esthetics,

monolithic crowns & bridges milled from zirconia are increasingly

being used as alternatives to traditional PFM restorations. In

this scientific overview, Glidewell Laboratories’ Ken Knapp explains

how the future of zirconia as a restorative material is rooted in the

efforts of material scientists to engineer nanocrystalline structures

that better approximate the optical translucency of natural dentition.

– Contents – 1


Publisher

Jim Glidewell, CDT

Editor-in-Chief and clinical editor

Bradley C. Bockhorst, DMD

Managing Editors

Jim Shuck; Mike Cash, CDT

Creative Director

Rachel Pacillas

Contributing editors

Greg Minzenmayer; Dzevad Ceranic, CDT;

David Casper; Tim Torbenson

copy editors

Eldon Thompson, Jennifer Holstein, David Frickman

digital marketing manager

Kevin Keithley

Graphic Designers/Web Designers

Jamie Austin, Deb Evans, Joel Guerra,

Audrey Kame, Lindsey Lauria, Phil Nguyen,

Kelley Pelton, Melanie Solis, Ty Tran, Makara You

Photographer/Clinical Videographers

Sharon Dowd; James Kwasniewski, Marc Repaire,

Sterling Wright

Illustrator

Phil Nguyen

coordinatorS/AD Representatives

Teri Arthur, Vivian Tsang

If you have questions, comments or suggestions, e-mail us at

inclusivemagazine@glidewelldental.com. Your comments may

be featured in an upcoming issue or on our website.

© 2011 Glidewell Laboratories

Neither Inclusive magazine nor any employees involved in its publication

(“publisher”) makes any warranty, express or implied, or assumes

any liability or responsibility for the accuracy, completeness, or usefulness

of any information, apparatus, product, or process disclosed, or

represents that its use would not infringe proprietary rights. Reference

herein to any specific commercial products, process, or services by

trade name, trademark, manufacturer or otherwise does not necessarily

constitute or imply its endorsement, recommendation, or favoring

by the publisher. The views and opinions of authors expressed

herein do not necessarily state or reflect those of the publisher and

shall not be used for advertising or product endorsement purposes.

CAUTION: When viewing the techniques, procedures, theories and

materials that are presented, you must make your own decisions

about specific treatment for patients and exercise personal professional

judgment regarding the need for further clinical testing or education

and your own clinical expertise before trying to implement new

procedures.

Inclusive is a registered trademark of Glidewell Laboratories.

Letter from the Editor

Turbulent economic times often motivate dentists to research

and incorporate new means of maintaining, or even growing,

their practices. One option is to expand service offerings. Mini

implants might be a good choice. Once considered for transitional

use only, small-diameter implants can provide a viable

long-term solution in appropriate cases, at an affordable price.

In this issue of Inclusive, we discuss access to dental care, as

well as utilization of small-diameter implants, with Dr. Michael

McCracken of the University of Alabama at Birmingham School

of Dentistry. We also have a follow-up article on the fabrication

of a mini implant overdenture by Dr. Christopher Travis. Online,

you can view the case appointment-by-appointment from preliminary

impressions to delivery of the final prosthesis.

Another goal might be to incorporate products that reduce costs

for both you and your patients. Due in part to the skyrocketing

price of gold, all-ceramic restorations continue to gain in popularity.

In fact, thanks to its high strength, low price point and

patients’ demand for improved esthetics, monolithic BruxZir ®

Solid Zirconia is the fastest-growing restoration in Glidewell’s

history. Included are two articles from our R&D group: one on

the optical properties of zirconia, and the other a finite element

analysis of the Inclusive ® All-Zirconia Custom Abutment.

As an adjunct to the abutment study, Dzevad Ceranic, CDT,

reviews the fabrication and use of jigs as an aid to delivering

abutments and screw-retained crowns easily and precisely.

Newer technologies can also help you provide a higher quality

of care to your patients while improving efficiencies. As a

superior diagnostic tool, CBCT is becoming a standard of care

for implant treatment. Dr. James Jesse reviews the use of this

3-D imaging to accurately identify the mandibular canal, while

Dr. Perry Jones demonstrates the use of intraoral scanning and

CAD/CAM fabrication of an abutment and crown to deliver a

model-free, implant-borne restoration.

It is our hope that the information contained in this publication

will provide insight into opportunities for strengthening your

practice in these challenging times. Please enjoy the issue and

take time to view the expanded content online.

Dr. Bradley C. Bockhorst

Editor-in-Chief, Clinical Editor

inclusivemagazine@glidewelldental.com

– Letter from the Editor – 3


Contributors

■ Bradley C. Bockhorst, DMD

After receiving his dental degree from Washington

University School of Dental Medicine,

Dr. Bradley Bockhorst served as a Navy Dental

Officer. Dr. Bockhorst is director of clinical

technologies at Glidewell Laboratories, where

he oversees Inclusive ® Digital Implant Treatment

Planning services and is editor-in-chief

and clinical editor of Inclusive magazine. A member of the

CDA, ADA, AO, ICOI and the AAID, Dr. Bockhorst lectures internationally

on an array of dental implant topics. Contact him

at 800-521-0576 or inclusivemagazine@glidewelldental.com.

■ VAHEH GOLESTANIAN, MSc

Vaheh Golestanian received a master’s degree

in biomedical engineering at Iran University

of Science and Technology in Tehran. In 2008,

he joined Glidewell Laboratories’ Implant R&D

and Digital Manufacturing department as

a manufacturing engineer. Vaheh has eight

years’ experience as a mechanical engineer

focused on finite element analysis and CNC programming,

and is a member of the Society of Manufacturing Engineers.

Contact him at inclusivemagazine@glidewelldental.com.

■ Grant Bullis, MBA

Grant Bullis, director of implant R&D and

digital manufacturing at Glidewell Laboratories,

began his dental industry career at

Steri-Oss (now a subsidiary of Nobel Biocare)

in 1997. Since joining the lab in 2007, Grant

has been integral in obtaining FDA 510(k)

clearances for the company’s Inclusive Custom

Implant Abutments. In 2010, he was promoted to director

and now oversees all aspects of CAD/CAM, implant product

development and manufacturing. Grant has a degree in

mechanical CAD/CAM from Irvine Valley College and an MBA

from the Keller Graduate School of Management. Contact him

at inclusivemagazine@glidewelldental.com.

■ JAMES JESSE, DDS

Dr. James Jesse graduated from Loma Linda

University in 1973 and has been in private

practice in Colton, Calif., for 34 years. An

associate professor of restorative dentistry

at LLU and an assistant professor of restorative

dentistry at Columbia University, he is

involved in research at both universities. Formerly

a member of the executive board of the World Clinical

Laser Institute and editorial board of Ascend Media, Dr. Jesse

lectures nationally and internationally, and is a member of

the ADA, AOD and AGD. Contact him at inclusivemagazine@

glidewelldental.com.

■ DZEVAD CERANIC, CDT

Dzevad Ceranic began his career at Glidewell

Laboratories while attending Pasadena

City College’s dental laboratory technology

program. In 1999, Dzevad began working at

Glidewell as a waxer and metal finisher, then

as a ceramist. After being promoted to general

manager of the Full-Cast department, he

assisted in facilitating the lab’s transition to CAD/CAM.

In June 2008, Dzevad took on the company’s rapidly growing

Implant department, and in 2009 completed an eightmonth

implants course at the UCLA School of Dentistry. Today,

Dzevad leads a team of 170 people at the lab and continues to

implement cutting-edge technology throughout his department.

Contact him at inclusivemagazine@glidewelldental.com.

■ Perry E. Jones, DDS, FAGD

Dr. Perry Jones received his DDS from Virginia

Commonwealth University School of Dentistry,

where he has held adjunct faculty positions

since 1976. He maintains a private practice in

Richmond, Va. One of the first GP Invisalign ®

providers, Dr. Jones has been a member of

Align’s Speaker Team since 2002, presenting

more than 250 Invisalign presentations. He has been involved

with Cadent optical scanning technology since its release to

the GP market and is currently beta testing the newest software

from Align Technology. Dr. Jones belongs to numerous

dental associations and is a fellow of the AGD. Contact him at

inclusivemagazine@glidewelldental.com.

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■ Ken Knapp

Ken Knapp joined Glidewell Laboratories in

March 2008 as a program manager in the

Materials Research and Development group.

He has 30 years’ experience in the synthesis

of magnetic and dental nanomaterials and

microfabricated magnetic recording head

devices. The last 10 years of his career have

been focused on researching and developing nanostructured

titanium dental devices and nanozirconia materials. Ken is

an inventor on 23 U.S. patents in the areas of magnetic and

dental nanostructured materials and devices. Contact him at

inclusivemagazine@glidewelldental.com.

■ David Leeson, MSc

David Leeson received a first class honors

degree in manufacturing engineering from

England’s Loughborough University, followed

by a Master of Science in advanced automation

and design from Cranfield University.

After graduation, he worked in the motorsports

industry, creating manufacturing processes

for high-precision racing engines. David is currently senior

manufacturing engineer in Glidewell Laboratories’ Implant

R&D and Digital Manufacturing department. After joining

Glidewell in January 2007, he used his engineering background

to launch many new products, including titanium and

zirconia abutments, as well as implant bars. He also led the

development of Glidewell’s automated machining capability.

Contact him at inclusivemagazine@glidewelldental.com.

■ CHRISTOPHER P. TRAVIS, DDS

Dr. Christopher Travis received his dental

degree and certificate in prosthodontics from

USC School of Dentistry, where he served as

an assistant clinical professor in predoctoral

and graduate prosthodontics. For the past

30 years, he has maintained a full-time private

practice specializing in prosthodontics in

Laguna Hills, Calif. Dr. Travis is director of the Charles Stuart

Study Group in Laguna Hills, prosthodontic coordinator for

the Newport Harbor Academy of Dentistry, and active member

of the Pacific Coast Society for Prosthodontics, American

College of Prosthodontists and AO, as well as a Fellow of the

ACD. Contact him at 949-683-7456 or surfnswim@fea.net.

■ Weihan Zhang, Ph.D

Weihan Zhang graduated from the University

of Missouri-Rolla (now Missouri University

of Science and Technology) in 2008 with a

Ph.D in mechanical engineering. Since joining

Glidewell Laboratories in 2008, Weihan

has been actively involved in software development,

prototyping machine and system

development projects as a manufacturing software engineer.

He has also published more than 20 articles on geometric

modeling and manufacturing engineering. Contact him at

inclusivemagazine@glidewelldental.com.

■ Michael McCracken, DDS, Ph.D

After completing dental school at the University

of North Carolina at Chapel Hill and a prosthodontic

residency at University of Alabama at

Birmingham, Dr. Michael McCracken received

a Ph.D in biomedical engineering for research

related to growth factors and healing of implants

in compromised hosts. Dr. McCracken is

a professor in the department of general dental sciences at UAB

School of Dentistry, where he has also served as associate dean

for education, director of graduate prosthodontics, and director

of the implant training program. He maintains an active

research program within the university and a private practice

focused on implant dentistry. He also lectures internationally.

Contact him at inclusivemagazine@glidewelldental.com.

– Contributors – 5


From Intraoral Scan to

Final Custom Implant Restoration

Go online for

in-depth content

by Perry E. Jones, DDS, FAGD

Introduction

This case demonstrates the optical scanning of Glidewell Laboratories’ purpose-made Inclusive ®

Scanning Abutments utilizing the iTero digital scanning system (Align Technology; San Jose, Calif.)

with software version 4.0. Digital data was used in conjunction with laboratory CAD/CAM planning to

fabricate custom all-ceramic implant abutments and a final 4-unit fixed prosthesis. The abutments and

fixed prosthesis were fabricated using advanced computer-aided milling technology.

Editor’s note: Cadent Inc. (Carlstadt, N.J.) was acquired by Align Technology (San Jose, Calif.) in May 2011.

6

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Dental History

The patient in this case was a 52-year-old healthy Hispanic

male who sustained a traumatic avulsion and loss of his

maxillary incisors in an automobile accident. Following

healing, the patient reported that a 4-tooth transitional

removable partial denture was constructed. He was seen

by the oral and maxillofacial surgery service of Virginia

Commonwealth University, as he desired dental implant

therapy. The patient reported multiple incidents of a

“broken” provisional denture (Fig. 1).

Treatment Plan

The patient was informed of the alternatives, benefits and

potential complications of various treatment options before

confirming his desire to pursue implant restoration

of his missing anterior teeth. The treatment plan included

placement of two Replace ® Select Straight RP 4.3 x 13 mm

implants (Nobel Biocare; Yorba Linda, Calif.) with 5 mm

healing abutments, followed by a six-month healing period

and restoration with all-zirconia custom abutments and a

4-unit all-ceramic fixed prosthesis to restore the anterior

incisors to form and function.

Surgical Procedure

Using local anesthesia, two Replace Select Straight RP implant

fixtures were placed in the area of tooth #7 and #10

using standard Nobel Biocare implant placement protocol.

Placement angulation and depth were verified and appeared

to be satisfactory (Fig. 2). Standard RP 5 mm healing

abutments were placed, and the fully reflected tissue flap

was closed with interrupted sutures (Fig. 3).

Figure 1: Patient presents with broken RPD. Note tight anterior coupling.

Figure 2: Osteotomies for implants #7 and #10 with guide pins

The patient was informed of the

alternatives, benefits and potential

complications of various treatment

options before confirming his

desire to pursue implant restoration

of his missing anterior teeth.

Figure 3: Post placement with 5 mm healing abutments and sutures

– From Intraoral Scan to Final Custom Implant Restoration – 7


Figure 4: Healing abutments at six months post implant placement

Figure 5: Right buccal view

Figure 6: Left buccal view

Figure 7: Maxillary occlusal view

Figure 8: Mandibular occlusal view

Figure 9: Panoramic view of implants at six months

Restorative Procedure

Following six months of healing post implant placement,

intraoral photos were taken to record and confirm

the healthy remaining dentition (Figs. 4–8). Osseous integration

was confirmed with a panoramic X-ray (Fig. 9),

followed by resonance frequency analysis (RFA) using an

Osstell ® ISQ implant stability meter with SmartPeg attachment

(Osstell Inc. USA; Linthicum, Md.) (Fig. 10), which

displayed an implant stability quotient (ISQ) of 78 on a

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Figure 10: Osstell ISQ implant stability meter

Figure 11: Replace Select Straight RP implants (Nobel Biocare)

with healing abutments

The 5 mm healing abutments

were removed and purpose-made

Inclusive Scanning Abutments were

placed and hand-tightened over the

implants with the accompanying

titanium screws.

Figure 12: Inclusive Scanning Abutment with attachment screw

Figure 13: Inclusive Scanning Abutments attached to implants (occlusal view)

Figure 14: Inclusive Scanning Abutments attached to implants (labial view)

minimum-to-maximum scale of 1–100. Counter rotation

with a torque wrench confirmed no rotation to 35 Ncm.

Based on this evidence of stability, the implant fixtures

were deemed to be acceptable for restoration.

The 5 mm healing abutments were removed (Fig. 11) and

purpose-made Inclusive Scanning Abutments (Fig. 12) were

placed and hand-tightened over the implants with the

accompanying titanium screws (Figs. 13, 14).

– From Intraoral Scan to Final Custom Implant Restoration – 9


Figure 15: iTero virtual scan (Align Technology)

Figure 16: Registering scanning abutment library to iTero virtual scan

Figure 17: Scanning abutments registered to iTero virtual scan

Figure 18: Abutment planning (labial view) with 3Shape's

DentalDesigner software and Prismatik CZ add-on module

The treatment plan included …

restoration with all-zirconia

custom abutments and a 4-unit

all-ceramic fixed prosthesis to

restore the anterior incisors

to form and function.

Figure 19: Abutment design (occlusal view)

Using the iTero scanner with updated software (version 4.0),

a full maxillary arch scan, full mandibular arch scan and

centric bite in maximum intercuspation were completed.

A three-dimensional digital record of the patient’s anatomy

was created from these scans (Fig. 15) and electronically

submitted to Glidewell Laboratories to be used in the CAD/

CAM restoration process.

At Glidewell Laboratories, the virtual scan was registered to

the scanning abutments (Figs. 16–17). This provides the dental

technicians with the implant system, size, axis, position relative

to the adjacent anatomy and locking feature orientation.

A virtual zirconia abutment was designed using 3Shape’s

DentalDesigner software (3Shape Inc.; New Providence,

N.J.) and the Glidewell Digital Abutment Library (Figs. 18–21).

10

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Figure 20: Abutment design (profile view)

Figure 21: Abutment design (lingual view)

A virtual zirconia abutment

was designed using 3Shape’s

DentalDesigner software and the

Glidewell Digital Abutment Library.

From this ... Inclusive All-Zirconia

Custom Abutments were milled.

Figure 22: Inclusive All-Zirconia Custom Abutments #7 and #10

Figure 23: Inclusive All-Zirconia Custom Abutment #7

Figure 24: Inclusive All-Zirconia Custom Abutment #10

From this, the corresponding physical Inclusive All-Zirconia

Custom Abutments (Glidewell Laboratories) were milled.

Similarly, a BruxZir ® Solid Zirconia 4-unit fixed bridge

(Glidewell Laboratories) was designed and milled using this

state-of-the-art CAD/CAM technology.

The custom zirconia abutments were trial-fitted in the

patient’s mouth with some slight tissue blanching noted

(Fig. 22). The individual close-up views demonstrate how

close the labial path of insertion passed to the head of each

abutment’s titanium screw (Figs. 23, 24).

– From Intraoral Scan to Final Custom Implant Restoration – 11


Figure 25: 4-unit BruxZir Solid Zirconia fixed bridge (labial view)

Figure 26: 4-unit BruxZir Solid Zirconia fixed bridge

(internal abutment view)

Figure 27: 4-unit BruxZir Solid Zirconia fixed bridge (labial view)

Figure 28: 4-unit BruxZir Solid Zirconia fixed bridge (occlusal view)

Figure 29: Final all-zirconia restoration

Figure 30: Happy patient!

12

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In the same visit, the completed 4-unit all-ceramic milled

BruxZir Solid Zirconia bridge was trial-fitted and examined

for proper occlusion (Figs. 25, 26). There was “tight” anterior

coupling for this case as evidenced by the history of provisional

denture fracture. The occlusion was checked and

presented as so precise that no adjustment was required.

The anterior view of the final prosthesis demonstrates optimal

mesial-distal width proportion, incisal edge proportion,

pontic-tissue contact and excellent shade/esthetics (Fig. 27).

Further, the occlusal view demonstrates an optimal incisal

edge arch form (Fig 28). The soft tissue lip position and

speech phonetics appeared to be optimal (Fig. 29). Following

the trial fitting, the fixed bridge was removed, the zirconia

abutment retention screws torqued to 35 Ncm, the abutment

screws covered with cotton/Cavit Temporary Filling

Material (3M ESPE ; St. Paul, Minn.), and the prosthesis

cemented with GC Fuji PLUS (GC America; Alsip, Ill.).

The final full-face photo demonstrates the pleasing smile

achieved with the restorative result (Fig. 30). IM

General References

• Baldissara P, Llukacej A, Ciocca L, Valandro FL, Scotti R. Translucency of zirconia

copings made with different CAD/CAM systems. J Prosthet Dent. 2010

Jul;104(1):6-12.

• Birnbaum NS, Aaronson HB. Dental impressions using 3D digital scanners: virtual

becomes reality. Compend Contin Educ Dent. 2008 Oct;29(8): 494, 496, 498-505.

• Chang YB, Xia JJ, Gateno J, Xiong X, Zhou X, Wong ST. An automatic and robust

algorithm of reestablishment of digital dental occlusion. IEEE Trans Med Imaging.

2010 Sep;29(9):1652-63.

• Christensen GJ. Will digital impressions eliminate the current problem with conventional

impressions? J Am Dent Assoc. 2008 Jun;139(6):761-3.

• Drago C, Saldarriaga RL, Domagala D, Almasri R. Volumetric determination of the

amount of misfit in CAD/CAM and cast implant frameworks: a multicenter laboratory

study. Int J Oral Maxillofac Implants. 2010 Sep-Oct;25(5):920-9.

• Ender A, Mehl A. Full arch scans: conventional versus digital impressions — an

in-vitro study. Int J Comput Dent. 2011;14(1):11-21.

• Fasbinder DJ. Digital dentistry: innovation for restorative treatment. Compend

Contin Educ Dent. 2010;31(4):2-11.

• Garg AK. Cadent iTero’s digital system for dental impressions: the end of trays and

putty? Dent Implantol Update. 2008 Jan;19(1): 1-4.

• Jones PE. Cadent iTero digital impression case study: full-arch fixed provisional

bridge. DC Dentalcompare. 2009 Jul 8 [cited 2011 Jul 28]. Available from:

http://www.dentalcompare.com/Featured-Articles/2082-Cadent-iTero-Digital-

Impression-Case-Study-Full-Arch-Fixed-Provisional-Bridge/.

• Jones PE. Cadent iTero optical scanning digital impressions for restorative and

invisalign. Dental Product Shopper. 2011 Jun 28 [cited 2011 Jul 29]. Available from:

http://dentalproductshopper.reachlocal.net/articles/cadent-itero-optical-scanningdigital-impressions-restorative-and-invisalign.

• Kurbad A. Impression-free production techniques. Int J Comput Dent.2011;14(1):

59-66.

• Priest G. Virtual-designed and computer-milled implant abutments. J Oral Maxillofac

Surg. 2005 Sep;63(9 Suppl 2):22-32.

• Smith R. Creating well-fitting restorations with a digital impression system.

Compend Contin Educ Dent. 2010 Oct;31(8):640-4.

• Touchstone A, Nieting T, Ulmer N. Digital transition: the collaboration between

dentists and laboratory technicians on CAD/CAM restorations. J Am Dent Assoc.

2010;141 Suppl 2:15S-9S.

• Zweig A. Improving impressions: go digital! Dent Today. 2009 Nov;28(11):100, 102,

104.

– From Intraoral Scan to Final Custom Implant Restoration – 13


Implant Q&A:

An Interview with

Dr. Michael McCracken

Go online for

in-depth content

Interview of Michael McCracken, DDS, Ph.D

by Bradley C. Bockhorst, DMD

Dr. Michael McCracken is a prosthodontist

and a professor at the University of Alabama

School of Dentistry. He maintains an active

research program within the university, as well

as a private practice in Birmingham focused

on implant dentistry. He sat down to discuss

his practical approach to this field of dentistry

during a recent visit to the Glidewell International

Technology Center.

– Implant Q&A: An Interview with Dr. Michael McCracken – 15


Dr. Bradley Bockhorst: Today, Mike, I’d like to talk

about one of the things that is near and dear to your

heart: the health effects of edentulism. Why don’t you

go ahead and tell us a little bit about what you’ve been

doing along that line, both at UAB School of Dentistry

and professionally.

Dr. Michael McCracken: Thanks, Brad. It’s nice to

be here. We have been learning a lot about edentulism

in the last 10 years or so. We are realizing how health

can be affected by the oral state, and how somebody

losing their teeth will lead to all kinds of systemic

problems, such as atherosclerosis or cancer. People

who have a denture, or who have a poor denture, take

a lot more GI medicine. So we are looking at ways that

we can treat that as a dental community. I think it’s an

exciting time to be in dentistry because now we have

implants. Now we have options that we didn’t have

many years ago that we can offer to patients. Instead

of telling them they have to have a denture, we can

offer them some valuable alternatives.

BB: One of the challenges we face as dentists is that

it’s our obligation to communicate to our edentulous

patients what is going on as far as bone loss. Maybe

you can share your thoughts along that line.

MM: I think about that sometimes. We know that one

of the leading lawsuits against dentists is the failure

to diagnose periodontal disease. So a patient goes to

their dentist whom they’ve gotten along well with for

20 years, and they’ve been going in every six months

for their checkup. They’ve been doing what they think

they should be doing on their side. Then one day the

dentist walks in and says: “Well, I’m sorry. You have

periodontal disease. And now you’re going to have to

lose these teeth, or you’re going to have to have this

surgery, or have these implants placed.” Understandingly,

the patient is upset by this and says: “Why didn’t

We know that one of

the leading lawsuits

against dentists is the

failure to diagnose

periodontal disease.

We are realizing how

health can be affected by

the oral state, and how

somebody losing their

teeth will lead to all kinds

of systemic problems.

you ever tell me about periodontal disease? Why didn’t

you ever tell me I had this disease in my mouth?”

They’re upset, and this causes some problems.

Sometimes I wonder: Will we see that with the edentulous

patient? Because now we have a similar situation.

We have a patient who has been going to a dentist

for 20 years. Maybe they come in every year or two

for a checkup or a denture adjustment. And then all

of a sudden they have problems with a mandibular

fracture, or they have a situation where they can no

longer successfully wear a lower denture, or they are

experiencing something else related to bone loss. And

maybe they’re going to ask their dentist: “Why didn’t

you ever tell me about this bone loss? Why didn’t you

ever tell me this was going on? Why didn’t you tell me

about this disease?” Because now we can effectively

treat that with implants.

BB: If dentists are not involved with implants, for

whatever reason, do they have an obligation to offer

them as an option to these patients to stop that potential

bone loss?

MM: Absolutely. Clearly, whether you offer those services

in your office, or you refer to a surgeon for implant

placement, the option has to be offered to the

patient. They just need to understand what’s going on.

We have some patients who learn the hard way the

effects of bone loss. As an example, we had a lady

who, after being edentulous for many, many years, had

her mandible resorb and resorb, becoming the size of

a pencil. She breaks her mandible as she is walking

out to the pool — stepped too hard, hit her jaw, and

now she has a fracture. It’s a very difficult revision

surgery — usually bilateral hip grafts — and quite a

bit of hospital experience. A lot a money and a lot of

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Not only are we

maintaining the bone

between the implants,

we are actually getting

bone maintenance or a

bone gain of up to

2 mm on average

behind the implant.

morbidity come with that when, if somebody had just

told her at the right time that they needed to put some

implants in there to maintain her bone levels, she

would’ve been much better off. Then it’s not a hospital

procedure; it’s an in-office procedure — very simple.

Instead of three days in the hospital, you have three

hours in the dental chair.

BB: Are there any studies or any research coming out

of UAB School of Dentistry that are related to being

able to maintain that bone level, or even in some cases

potentially increase it?

MM: Yes. And we did see an increase in bone levels,

surprisingly to me, in a study that was done by the

periodontists at UAB, which was a prospective clinical

trial, long-term, about eight years. And we restored

these patients with five implants in the anterior mandible

and a very traditional Brånemark style, with about

3 mm between the prosthesis and the edentulous

ridge. We noticed over time — this was back in the

nineties — that the tissue would proliferate and touch

the bottom of the bridge. The periodontist thought

we had better clean that up or take that down, so the

patient would have access to clean. When they went in

there to remove that soft tissue, it wasn’t soft tissue; it

was bone. So we measured that as part of this clinical

trial, and we saw 1.5 mm, some patients 2 to 3 mm,

of bone gain distal to the implant. So not only are we

maintaining the bone between the implants, we are

actually getting bone maintenance or a bone gain

of up to 2 mm on average behind the implant. So as

we are adding stress back to this system, the bone is

responding by increasing in volume and density.

BB: That leads into one of your other primary interests:

talking to patients about bone loss, and giving them

solutions that are affordable. Maybe you can share

with us a little bit about what you’ve done at the school

as far as low-cost options for restoring these patients.

MM: Certainly. I do think that is critically important. If

we believe that implants are important, as we do as a

profession, then how can we help more of our patients

get into implants? How can we assist our patients,

let them experience implant dentistry and enjoy those

benefits? At the school, we have developed a lowcost

program that we have offered to our patients.

Of course, keep in mind it’s a dental school, and we

have students working on these. But we have provided

the two-implant overdenture, which is just a basic,

entry-level implant prosthesis. We give them the two

implants, the two dentures and the two attachments

for around $1,500. Most people we find can get into

that with a little bit of desire. Most patients are very

satisfied with that price point, and we are able to help

them maintain their bone, get rid of a complete denture

and move into an implant-supported prosthesis.

BB: I believe you’re also doing some ongoing work

with 3 mm diameter implants?

MM: We are. To me, this is an interesting potential solution

to some of the costs associated with traditional

implant systems: single-piece overdenture implants.

These are available generally in different sizes, around

3 mm or a little smaller. We wanted to make sure that

this treatment modality was going to be successful

for our patients. We did a clinical trial with about 45

patients, and we randomized those to two, three or

four 3 mm diameter implants in the mandible. I was

really surprised at the results. I’m generally conservative

when it comes to loading protocols, time and so

forth. Obviously, with a one-piece implant, you can’t

have delayed loading. So we had immediate loading at

the time of placement, and we had a relatively smalldiameter

implant. Clinically, the results were excellent.

I’m gaining much confidence in this treatment

modality.

BB: I know the results haven’t been published yet, but

do you have a preference for the number of implants

— two, three, four? Typically when we start getting into

the smaller diameters, they’re saying four implants in

the symphysis. What is your take on this?

– Implant Q&A: An Interview with Dr. Michael McCracken – 17


We found no difference

between two or four

implants, in terms of

implant survival or bone

loss around the implants.

MM: That was the main question: Do you have to do

four? Because if you’re going for a low-cost alternative,

it would be cheaper to do two. And, indeed, we found

no difference between two or four implants, in terms

of implant survival or bone loss around the implants.

So two implants, in our study, worked very well.

BB: Some people call the 3.0 implants “hybrids” because

they are getting close to that conventional diameter,

as opposed to the very narrow implants — the true

small diameters. Would you have a different approach

if you went smaller than a 3.0?

MM: I’ve still been a little nervous about the smallerdiameter

implants. I just haven’t had a lot of clinical

experience with them myself, coming from a more

conventional approach with standard-diameter implants.

But the results that we got from the 3.0 are

encouraging me to try something a little bit more narrow,

because there are times when that’s very helpful.

I mean, many patients have a narrow ridge, and you’re

faced with the clinical decision of, am I going to remove

6 or 7 mm of bone height so I can get sufficient

width for my implant? Or am I going to simply place a

small-diameter implant? I think maybe we’ll be going

more toward the direction of the smaller implants as

we move forward with this.

BB: On the subject of bundling prices to get implant

treatment to an affordable level for patients, you mentioned

bundling two implants, two dentures and two

attachments. Do you have something else if you’re going

to do four 3.0? Have you gotten into a bundle for

that, or is that still a work in progress?

MM: For the students, it’s still a work in progress. For

my own practice, I think that is very exciting. I love

what Glidewell has done with the package concept

because it really simplifies things for me as a clinician

to know: This is your cost, these are your implants, get

the overdenture for that. Then I can translate that into

a clinical situation with a patient who really wants to

get implants, and who I really want to get into implants.

It simplifies things for everybody. I definitely

plan to pass those cost savings on to the patients.

BB: I understand that outside of the dental school, you

are getting involved in a community clinic. Do you

want to share a little bit of why you got involved with

that and what your plans are with it?

MM: Sure. We set up a community clinic outside of

Birmingham. We’re associated with a drug-addiction

recovery program down there, but we’re also open for

community patients who don’t have much access to

care. And I have to say, it is one of the most rewarding

things I do — even with being a teacher, which is rewarding

in itself. To help people who don’t have other

avenues for dental work is extremely exciting. It’s a

big volunteer effort from a number of organizations

down there involved with that. But we’re planning on

offering them the best dentistry we can, and that’s definitely

going to include implants.

BB: That ties right into bundled pricing, where you

can offer services at very affordable prices.

MM: That’s right. We have a lot of edentulous folks in

Alabama — sixth highest in the States is our ranking

now, I believe. So we have plenty of people needing

implant overdentures.

BB: Do you know what the percentage is?

MM: For our seniors, age 65 and over, it’s more than

30 percent now in Alabama that are edentulous. And

that’s fairly consistent with other states.

BB: We’ve talked a lot about restoring the lower edentulous

ridge. What do you typically do in the maxilla?

MM: The maxilla is a little more of a challenge. The

bone is less dense, of course, and the implants are less

predictable in the maxilla. I’ve always been an advocate

of multiple implants tied together — be it with a

bar, be it with a fixed prosthesis. But lately I’ve had

success with individual implants and a cobalt chromium

framework to give structure to the prosthesis, so

that we have some form of cross-arch stabilization and

some splinting from that rigid metal framework. So in

the maxilla, now I’m moving more toward four implants

with attachments using that metal substructure.

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BB: If you go that route — four implants and a cast

framework — are you going palate-less, or are you still

doing complete palatal coverage?

MM: I have to say I’m about fifty-fifty on it. Occasionally

I’ll take the palate out. I think that’s pushing the

limits a little bit. I certainly see that it works in some

patients, but I try to talk the patients into a palate. I

think it gives me more comfort than anything else.

BB: Another study coming?

MM: That would be a great study — six implants, no

worries.

BB: Is there anything else exciting going on at the

school or for you personally?

MM: Tough question. I was walking through Glidewell

Laboratories, and I’m really excited about the

milled BioTemps ® that are coming out now. They look

beautiful. I’ve always been thrilled with BioTemps, the

pricing and the esthetics, especially long-term. As a

prosthodontist I have patients’ cases for 12, 15 months

waiting for grafting or whatever, and the BioTemps

have held up really well for me. I like the milled

approach they’re taking now. It just seems to be a neat

technological advancement.

BB: Yes. Everything is going CAD/CAM. It provides a

more predictable, consistent result.

MM: I think it won’t be too long from now when I can

just take a scan of the arch, not even have to make a

cast, and you guys can send me a BioTemps full arch.

BB: Yes, that’s coming. Let’s step back a minute and

talk about your thoughts on cone-beam scanning,

on using it as a diagnostic tool for those edentulous

patients. Do you do it just for diagnostic purposes? Do

you head toward guided surgery? When would you

use a guide versus doing a flap?

MM: For me, I find that a flap is useful in many of my

surgical approaches. That may be because I need to

manipulate the soft tissue. I may need a grafting in a

certain situation. We may need to thicken the soft tissue.

So, for a variety of reasons, I find that I’m laying a

lot of flaps. For the perfect patient with abundant bone

and abundant keratinized tissue, there’s nothing easier

than a guided surgery. With a placement, to have the

confidence and predictability of knowing the anatomy,

you can’t beat that, knowing that your implant is going

to come out in the right spot.

BB: At the school, are you guys routinely CT scanning

those patients?

MM: Routinely? No. For me, if the patient has abundant

bone, I don’t really need to scan. If the patient

has very inadequate bone, sometimes I don’t need to

scan to tell. I know I need to graft. It’s the patients

in the middle, certainly large cases, where CBCT is a

great help — especially for the patients where you really

don’t know what your approach is going to be. Do

we need to graft? Can we place the implant and graft

simultaneously? Many of these questions are answered

with a cone-beam scan.

BB: We talked about the health effects of edentulism

and keeping patients informed of implants as an option,

particularly implants and prosthetics on top of

them as an affordable option. Do you have any final

thoughts or comments on this?

MM: I think we should be using the fixed prosthesis

more. I see a lot of people who are very comfortable

with the two-implant overdenture, the four-implant

overdenture. I think the fixed prosthesis, a traditional

Brånemark hybrid prosthesis, is one of the best things

we can do for folks, and I’d love it if we were doing a

lot more.

BB: How many implants do you usually like to do for

your hybrids?

MM: Traditionally, I like five, but I’m very comfortable

with four. They can be straight. They don’t have to

be tilted. The literature clearly supports four implants

in the anterior mandible. And, just recently, I read an

article that showed good success on three. So maybe

we are even pushing the limit in that direction as well.

But I think four or five implants is very reasonable.

BB: OK, great. So what do they say in ’Bama?

MM: Roll Tide.

BB: There you go. IM

– Implant Q&A: An Interview with Dr. Michael McCracken – 19


Optimizing the Design of Zirconia Implant

Abutments: A Finite Element Analysis

by Vaheh Golestanian, MSc; David Leeson, MSc;

Grant Bullis, MBA; and Weihan Zhang, Ph.D

INTRODUCTION

Esthetic concerns are essential for anterior tooth restorations. Zirconia is a widely used engineering ceramic considered to

have high load strength and fracture toughness compared to other ceramic materials used in dentistry. It is also a highly

biocompatible ceramic material less prone to discoloring the cervical soft tissues than metal abutments. 1 Zirconia, like other

ceramics, is sensitive to tensile stresses and extreme care must be taken to design the prosthetic connection to the implant

so that tensile stresses are minimized. Manufacturing small, high-precision components from zirconia is challenging, and it

requires rigorous attention to detail in every aspect of the manufacturing process. Small defects introduced during manufacturing

can lead to fractures, and poor tolerance control can lead to rotational play between abutment and implant, which

can result in loosening of the abutment’s retaining screw. 2,3

– Optimizing the Design of Zirconia Implant Abutments: A Finite Element Analysis – 21


For proper prosthetic function, zirconia abutments must

exhibit performance characteristics comparable to those

of traditional titanium abutments. 4 Zirconia has a higher

compressive strength compared to titanium alloy. However,

under cyclic loading situations, zirconia abutments will

fracture when overloaded, while a titanium abutment will

undergo plastic deformation. ISO 14801:2007 is the fatigue

testing standard for endosseous dental implants. 5 With this

procedure, the implant and abutment assembly is cyclically

loaded to determine its fatigue limit. The fatigue limit

will be reached at lower loads if the prosthetic connection

geometries of zirconia abutments are left identical to titanium,

rather than being optimized for the intrinsic material

properties of zirconia.

METHODS AND MATERIALS

The initial abutment design used in this study was Glidewell

Laboratories’ titanium abutment CAD model. A threedimensional

finite element model was generated from the

abutment and implant by importing these CAD models into

COSMOSWorks software (Fig. 1). For simplicity, the implant

threads were removed and the abutment screw was modeled

by beam elements.

The implant material was defined as commercially pure

titanium, grade 4. The abutment screw material was

defined as Ti-6AL-4V titanium alloy, and was tightened to

35 Ncm torque.

Since repeated cyclic loading of implants induces plastic

deformation, it is normally recommended to conduct a

nonlinear finite element analysis. 6 However, in this study,

a linear analysis was performed as a simplification. This

assumption is justified by the following:

1. The maximum applied force (250 N) produces a very

small region of plastic deformation on the implant,

so the deviation between linear and nonlinear analysis

would be relatively small and adequate for design

optimization, but not an absolute indication of the

strength of the abutment.

2. Contact analysis is possible in linear mode with COS-

MOSWorks. It was assumed that the relative movement

between abutment and implant would be negligible

and would not significantly affect the analysis results.

The model was restrained from the implant’s body, 3 mm

beneath the contact face of the abutment and implant, and

a static, oblique force of 250 N was applied at a 30-degree

For proper prosthetic

function, zirconia abutments

must exhibit performance

characteristics comparable

to those of traditional

titanium abutments.

Figure 1: CAD model of the abutment

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angle to the long axis of the implant. Three-dimensional

tetrahedral solid elements were used to mesh the abutment

and implant, and a beam element for the abutment screw

(Fig. 2). Static analysis was conducted to optimize the design

of the abutment.

Several features of the abutment were changed during the

design optimization to increase the strength of the zirconia

abutment assembly. Some of these features were the

abutment screw bore diameter and radius, the distance between

the screw seat and contact face of the abutment and

implant, the abutment screw shank bore diameter, and the

profile of the platform (Fig. 3). A total of 46 iterations of

these features were analyzed. Mohr-Colomb yield criterion

was used for calculating the safety factor of the abutment,

and Von-Mises yield criterion used for calculating the safety

factor of the titanium implant.

abutment screw

head bore

abutment screw

shank bore

screw head

seat

Figure 2: Meshing complete. The implant is constrained at its body and apex. A

force of 250 N is applied to the abutment.

Figure 3: Different features of abutment screw seat

On the mating surface between the implant and abutment,

a surface-to-surface contact condition without penetration

was chosen. For the abutment connection, a node-to-surface

contact condition was chosen. In both cases, the implant

was selected as the source, and the abutment as the target.

The abutment was selected as the target because it had a

higher modulus of elasticity. 7 The mesh was refined in contact

areas and around small features.

RESULTS

Several features of the

abutment were changed

during the design

optimization to increase

the strength of the zirconia

abutment assembly.

– Optimizing the Design of Zirconia Implant Abutments: A Finite Element Analysis – 23


On the abutment, there were three areas requiring attention

to ensure an adequate factor of safety (FOS):

1. The mating surface between the implant and abutment

2. The abutment screw head mating surface

3. The abutment prosthetic connection geometry

Under load, localized areas on the implant’s mating surface

reach the yield point, upon which this area expands downward.

This pattern is similar to what has been observed

during previous tests of titanium abutments according to

ISO 14801:2007 (Fig. 4).

For comparison, a zirconia abutment with connection

geometry not optimized for zirconia was analyzed alongside

a zirconia abutment with connection geometry optimized

for zirconia. The abutments were identical except for

the connection geometry. The results are shown in Figure 5.

Figure 4: A force of 250 N applied to the abutment and implant with contact on

the mating surface and connection geometry. The safety factor ranges from 0.704

for the implant and 2.125 for the abutment optimized for zirconia vs. 0.202 for the

implant and 0.903 for the non-optimized abutment.

Model:

Non-optimized connection

Optimized (Inclusive ® ) connection

Contact Condition: Implant and abutment are in contact only on the mating surface Implant and abutment are in contact only on the mating surface

Min. FOS in Abutment: 2.519 2.429

Min. FOS in Implant: 0.6731 0.7953

Contact Condition:

Implant and abutment are in contact on the mating surface and

connection geometry

Implant and abutment are in contact on the mating surface and

connection geometry

Min. FOS in Abutment: 0.9029 2.125

Min. FOS in Implant: 0.2018 0.7041

Figure 5: Comparison between non-optimized and optimized connection geometry

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DISCUSSION

In this study, the zirconia abutment assemblies were analyzed

in static and linear conditions. Figure 5 details the

comparison between a zirconia abutment with geometry

not optimized for zirconia and an otherwise identical zirconia

abutment with connection geometry optimized for

zirconia. The mating surface factors of safety for both

abutments are nearly identical. However, when the abutment

connection geometry contacts the implant connection

geometry, the minimum factor of safety drops to 0.903 on

the non-optimized zirconia abutment, compared to 2.125

on the Inclusive ® All-Zirconia Custom Abutment from

Glidewell Laboratories. The Inclusive All-Zirconia Custom

Abutment achieves the higher factor of safety by optimizing

the connection geometry for the material properties of the

zirconia. Specifically, the connection height is reduced to

minimize the potential transmission of tensile loads, sharp

corners are removed from the connection, and the implant

mating surface is undercut to provide clearance.

The shanks of zirconia abutments screws are smaller compared

to those used for titanium abutments. The smallerdiameter

shanks stretch more and generate higher preload

in the screw from the same amount of torque. This increased

The Inclusive All-Zirconia

Custom Abutment achieves

the higher factor of safety by

optimizing the connection

geometry for the material

properties of the zirconia.

Increased preload improves

the performance of the

connection between the

implant and abutment,

inhibiting risk of the screw

loosening over time.

preload improves the performance of the connection between

the implant and abutment, inhibiting risk of the screw

loosening over time.

The fracture toughness of fully sintered zirconia is about

13 MPa(m ½ ) compared to titanium alloys, which are about

75 MPa(m ½ ). This makes zirconia vulnerable to cracks

and faults. The manufacturing process for zirconia abutments

requires very precise, repeatable machinery and a

well-controlled sintering process to produce abutments that

fit and perform well.

CONCLUSION

Zirconia is an engineering ceramic with great potential for

implant abutments. Zirconia has good esthetics and high

compressive strength, but lower tensile strength and fracture

toughness relative to titanium. Because of this, zirconia

abutments have to be designed with these material properties

in mind. The material properties of zirconia require a

specially designed prosthetic connection to minimize the

potential for breakage.

– Optimizing the Design of Zirconia Implant Abutments: A Finite Element Analysis – 25


Finite element analysis (FEA) provides a valuable tool to

evaluate and optimize multiple designs prior to manufacturing

physical components. Using FEA, engineers can evaluate

multiple zirconia abutment and screw designs to minimize

tensile loads in the abutment connection geometry

and maximize preload of the abutment screw. IM

REFERENCES

1. Butz F, Heydecke G, Okutan M, Strub JR. Survival rate, fracture strength and failure

mode of ceramic implant abutments after chewing simulation. J Oral Rehabil.

2005 Nov;32(11):838-43.

2. Kim SK, Lee JB, Koak JY, Heo SJ, Lee KR, Cho LR, Lee SS. An abutment screw

loosening study of a Diamond Like Carbon-coated CP titanium implant. J Oral

Rehabil. 2005 May;32(5):346-50.

3. Garine WN, Funkenbusch PD, Ercoli C, Wodenscheck J, Murphy WC. Measurement

of the rotational misfit and implant-abutment gap of all-ceramic abutments.

Int J Oral Maxillofac Implants. 2007 Nov-Dec;22(6):928-37.

4. Gehrke P, Dhom G, Brunner J, Wolf D, Degidi M, Piattelli A. Zirconium implant

abutments: fracture strength and influence of cyclic loading on retaining-screw

loosening. Quintessence Int. 2006 Jan;37(1):19-26.

5. ISO 14801:2007. Dentistry — Implants — Dynamic fatigue test for endosseous

dental implants.

6. Cehreli MC, K. Akça K, H. Iplikçioglu. Force transmission of one- and two-piece

morse-taper oral implants: a nonlinear finite element analysis. Clin Oral Implants

Res. 2004 Aug;15(4):481-89.

7. SolidWorks Web Help

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Lab Corner:

Accurately Seating

Inclusive® Custom Abutments

Using an Acrylic Jig

Go online for

in-depth content

by Dzevad Ceranic, CDT

In processing restorations for more than 100,000

implant cases, the Implant department at Glidewell

Laboratories has accumulated a unique understanding of the

industry as a whole, observing everything from shifting trends,

to emerging techniques, to common difficulties experienced by

practicing clinicians. In this column, we endeavor to share some

of the insights we have obtained, in hopes of improving the quality

and efficiency of cases everywhere.

Among the most popular products in implant dentistry

today are CAD/CAM custom abutments. An investment in

cutting-edge digital technology and state-of-the-art milling

equipment here at Glidewell Laboratories enables us

to efficiently and precisely design and mill our own Inclusive

® Custom Implant Abutments. In our experience, custom

abutments are superior in almost every way to stock,

off-the-shelf abutments. After all, a restoration is only as

good as the foundation on which it is placed. And if that

foundation is less than ideal in terms of size, shape, angulation

or tissue contour, the success of that restoration could

be compromised.

Inclusive Custom Implant Abutments are available in three

varieties: Titanium, All-Zirconia or Zirconia with Titanium

Base. Titanium is most often the choice for posterior restorations

because the popular perception among dentists

is that this metal alloy must be stronger than zirconia. Our

testing data suggests that this may not necessarily be true,

in that a properly designed zirconia connection has been

shown to tolerate greater loads than a titanium connection.

The traditional opinion persists, it seems, due to the fundamental

nature of a metal, which deforms under stress, versus

a ceramic, which fractures. Regardless, the most widely

accepted advantage of a zirconia abutment is its improved

esthetics. Having a tooth-colored foundation, rather than a

metal one, allows the lab technician to increase the translucency

of the crown or bridge. It also eliminates the risk of

the gray color of the metal shining through thin soft tissue.

For this reason, zirconia abutments are more often used in

the esthetic region (Fig. 1).

This brings us to the question of which type of zirconia

abutment — All-Zirconia or Zirconia with Titanium Base

— should be used. Considerations here are two-fold. One

is the length of the abutment connection (the post-like section

of the abutment that engages into the implant). Zirconia

connections are designed to be short for improved

strength — superior even to the strength of a titanium connection*

— but this shortened length can sometimes present

a challenge in terms of verifying complete seating of

the abutment onto the implant. Titanium connections are

longer (Fig. 2), making them easier to seat, assuming adequate

vertical clearance. The second consideration, however,

goes back to the difference in esthetics. With a titanium

base, there remains the small risk of the appearance of

metal showing through around the base of the abutment.

With an all-zirconia abutment, this potential drawback is

eliminated.

*Editor’s note: For more on the comparative strength of zirconia and titanium connections, see article on optimizing the design of zirconia implant abutments, page 21.

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Figure 1: Graph depicting usage of custom abutment type by tooth number at Glidewell Laboratories

Figure 2: A visual comparison of titanium and zirconia abutment connections

– Lab Corner: Accurately Seating Inclusive Custom Abutments Using an Acrylic Jig 29


In terms of practical use, how does the clinician who desires

an all-zirconia custom abutment ensure proper seating? For

the lab technician, seating the abutment on a model is easy.

The model can be turned or twisted as needed to achieve

optimal orientation, and there are no other anatomical

structures or tissues to get in the way. A patient in the chair,

however, is another matter. There’s only so much freedom

the clinician has in terms of orientation to gain access to the

implant site. And there are cheeks, teeth, the tongue and

soft tissue to contend with. In addition, the lab technician

is frequently more familiar with the line of draw as a result

of the intimacy gained during the design process. Without

spending the same amount of time relating the abutment to

the patient’s mouth, the doctor cannot be expected to have

this level of familiarity.

To help solve this clinical challenge and ensure proper

seating of the abutment, an acrylic jig can be made, which

serves as a positioning index and placement aid. From

Glidewell, this jig is shipped in the case box in a plastic

baggie separate from the abutment (which is seated on the

model). Upon close examination, you will see that both the

jig and the abutment are marked with the appropriate tooth

number along the facial wall (i.e., labial or buccal). Thus, if

your case includes multiple abutments, each abutment can

easily be matched to the correct jig.

Laboratory Example

Figures 3–5 illustrate an Inclusive All-Zirconia Abutment

with jig, as prepared on a laboratory model.

Figure 3: Jig designed to carry an Inclusive All-Zirconia Abutment

Figure 4: Checking access opening for Torque Wrench Driver

To … ensure proper seating

of the abutment, an

acrylic jig can be made,

which serves as a positioning

index and placement aid.

Figure 5: Abutment seated on model

30

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Clinical Delivery

The following procedure outlines the specific steps for placing

an Inclusive All-Zirconia Abutment with its matching jig.

As noted, the same steps may be applied when placing other

Inclusive Custom Abutments or screw-retained restorations.

To properly seat a custom abutment with its custommatched

jig:

1

2

Match the selected abutment to the jig with corresponding

tooth number on the model (Fig. 6).

Place the abutment in the jig. For proper orientation,

vertically align the number marked on the abutment to

the number marked on the jig. The two should slide

together easily.

3

4

5

6

Using the jig as a carrier, deliver the abutment to the

patient’s mouth.

Align the numbers marked on the jig and carrier with

the facial wall of the patient’s arch (i.e., labial or buccal).

When properly aligned, apply pressure to seat the jig

and abutment. Proper seating of the jig will help ensure

full seating of the abutment (Fig. 7).

Using your driver, insert the abutment screw and tighten.

Note that the jig will also maintain the position of

the abutment while the screw is tightened to the recommended

torque (Fig 8).

Remove the jig, leaving the tightened, fully seated abutment

in place (Fig. 9). A periapical film should be taken

to ensure complete seating.

Figure 6: Jig marked with corresponding tooth number

Figure 7: Jig oriented in the mouth to ensure proper abutment alignment

Figure 8: Tightening the abutment screw with jig in place

Figure 9: Final seating of the Inclusive All-Zirconia Abutment

– Lab Corner: Accurately Seating Inclusive Custom Abutments Using an Acrylic Jig 31


Alternate Uses

of the Laboratory Jig

®

Screw-Retained BruxZir Solid Zirconia Crown

The use of a jig is not limited solely to custom implant abutments.

It may also be used to seat single-unit, screw-retained

restorations. The following images (Figs. 10, 11) illustrate a

screw-retained BruxZir ® Solid Zirconia crown with jig, as

prepared on a laboratory model.

Multiple-Unit Bridge

A jig may also be used for multi-unit applications. The following

images (Figs. 12–14) illustrate a pair of Inclusive

Titanium Abutments with accompanying jig, as prepared on

a laboratory model. In this case, the abutments will be used

to support a multi-unit bridge.

Figure 10: Checking Torque Wrench Driver access for a jig on a screw-retained

BruxZir crown.

Figure 11: Screw-retained BruxZir crown on model

Figure 12: Jig carrying tooth #18 and #19 abutments; jig for tooth #21 seated

Figure 13: Jigs and abutments on model

Figure 14: Inclusive Titanium Abutments seated on model

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Delivery of a Screw-Retained BruxZir Solid Zirconia Crown

The same procedure used to seat an Inclusive Custom Abutment can be used to ensure proper seating of a screw-retained

BruxZir Solid Zirconia crown, as demonstrated by the following images (Figs. 15–17b).

Figure 15: Jig used to carry and seat a screw-retained BruxZir crown

Figure 16: Abutment screw tightened to recommended torque

17a

17b

Figures 17a, 17b: Seated screw-retained BruxZir crown

Summary

All-zirconia custom implant abutments offer a natural esthetic

and significant abutment connection strength, but

the short length of the abutment connection can pose a

clinical challenge when it comes to proper seating. Using

the jig-assisted delivery technique outlined above makes

the process of seating any Inclusive Custom Implant Abutment

quick and convenient, no matter the length of the

implant-abutment connection. It works well for single-unit

restorations, and even better for bridges, where a single

jig is used to seat multiple units. (This is typically limited

to three units per jig, as larger spans can become cumbersome

to handle in the mouth.) With this method, doctors

have seated a full-arch roundhouse in a matter of minutes.

All the clinician has to do is ensure proper alignment between

abutment and jig, and then again between jig and

implant site. If the lab has done its job correctly, the precise

nature of digital CAD/CAM processing will ensure a

successful outcome every time. IM

– Lab Corner: Accurately Seating Inclusive Custom Abutments Using an Acrylic Jig 33


Clinical Case Report:

Delivery of a Mini Implant-Retained

Mandibular Overdenture

Go online for

in-depth content

by Christopher P. Travis, DDS

The placement of small-diameter

“mini” implants in the edentulous

mandible is designed to allow for the

immediate loading of an implant-retained

overdenture, provided primary stability is

achieved. If the patient’s existing denture

presents an acceptable fit with proper extensions and balanced occlusion, it may be used as the final prosthesis following

a hard reline performed chairside to pick up the O-ring implant attachments. If the existing denture needs to be replaced,

however, the accepted protocol is to perform a soft reline and use it as a provisional prosthesis only, while the attachments

are incorporated into the new, lab-fabricated overdenture. 1 In this follow-up to a clinical case report documenting the placement

of 3.0 mm diameter mini implants (Inclusive, Vol. 2, Issue 2), we detail the process of delivering a new mandibular

overdenture to a patient following osseointegration.

Case Planning and Surgical Review

Seeking to improve the function and stability of her traditional mandibular denture, the fully edentulous patient in this

case underwent the minimally invasive placement of four Inclusive ® Mini Implants (Glidewell Laboratories) in the anterior

mandible utilizing a digital treatment plan and guided surgery. 2,3 The virtual planning process helped to confirm adequate

bone width and quality, identify vital structures, and determine the ideal location and angle of insertion (Fig. 1). With the

resulting surgical guide helping to ensure accuracy and parallelism during physical placement, there was no need for soft

tissue reflection, thereby minimizing patient trauma, required healing time and the duration of the procedure (Figs. 2, 3).

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Figure 1: Preoperative digital treatment plan

Figure 2: Guided surgical placement of mini implants

Figure 3: Postoperative view of fully seated mini implants

Figure 4: Soft reline of patient’s existing denture. Note lingual flange extensions.

CASE TIMELINE

Appointment

#1

Appointment

#2

Appointment

#3

Appointment

#4

Appointment

#5

Appointment

#6

Appointment

#7

Radiographic

Markers Added

to Denture

CBCT

Implant

Placement and

Soft Reline

Preliminary

Impressions

Final

Impression

Occlusal

Records

Tooth/Shade

Selection

Trial Denture

Try-in

Delivery

Digital

Treatment Plan

(4 days in lab)

Patient Healing

(0–3 months)

Custom Tray

(2 days in lab)

Bite Block/

Master Cast

(2 days in lab)

Trial Denture

Setup

(3 days in lab)

Process

Overdenture

(5 days in lab)

Fabrication of

Surgical Guide

(7 days in lab)

The placement of small-diameter “mini” implants in the edentulous mandible

is designed to allow for the immediate loading of an implant-retained overdenture,

provided primary stability is achieved.

Although primary stability of the implants was achieved, the patient’s existing denture had been heavily

modified with deep extensions of the lingual flanges (Fig. 4). 4 It was therefore determined that she would be

better served with a new prosthesis. After doubling as a radiographic guide in the digital planning phase,

the patient’s existing denture was relieved and soft-relined at the time of surgery for a passive fit over the

– Clinical Case Report: Delivery of a Mini Implant-Retained Mandibular Overdenture – 37


Figure 5: Initial impression of the mandibular arch

Figure 6: Maxillary impression for the opposing cast

Because Inclusive Mini Implants have a

one-piece design, there is no abutmentto-implant

interface, eliminating any gap

problems or micro-leakage associated

with standard, two-piece implant designs.

Figure 7: Adjustment of the provisional prosthesis

implant heads. The patient was thus able to wear her modified existing denture as a provisional prosthesis while the final

Inclusive Mini Implant Overdenture was fabricated. With consideration given to the elderly patient’s bone quality, a timeline

of two months was established to ensure full osseointegration prior to her first prosthetic appointment.

First Prosthetic Appointment: Preliminary Impressions

Approximately two months after guided surgical placement of the four mini implants, the patient returned to the office

for an inspection of the implant sites. A sore spot was noted, due to a slight overextension of the denture border in the

anterior section, but overall tissue health and implant stability was deemed acceptable for proceeding with the fabrication

of a permanent prosthesis incorporating the O-ring attachments.

For the purpose of making custom trays, an initial impression was made of the lower arch using irreversible hydrocolloid

(alginate) material in a stock tray (Fig. 5). This impression revealed the location of the O-ball abutments. To avoid potential

inaccuracies, the patient was instructed to close slightly, allowing the muscles of mastication to relax. Upon removal, the

first impression revealed a minor imperfection caused by tongue placement during insertion of the stock tray. Rather than

risk future complications, the impression was remade.

Following a satisfactory lower impression, an initial impression was made of the upper denture for the opposing cast, to

be saved for teeth-in-wax placement (Fig. 6). Both mandibular and maxillary impressions were poured up immediately with

improved gypsum stone.

The soft liner of the provisional prosthesis was adjusted slightly in the lingual flange area due to the patient’s sore spot

(Fig. 7). The denture was then cleaned, and bilateral balancing occlusion was confirmed.

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Figure 8: Inclusive Mini Implant Impression Copings fully seated

Figure 9: Border molding material applied to custom tray

Figure 10: Border captured along first half of arch

Figure 11: Border captured along second half of arch

Second Prosthetic Appointment: Final Impression

With a custom tray fabricated by the laboratory from the preliminary mandibular impression, the patient

returned to have border-molded impressions made that would be used to create the master cast.

The Inclusive Mini Implants were inspected and found to be clean. Because Inclusive Mini Implants have

a one-piece design, there is no abutment-to-implant interface, eliminating any gap problems or microleakage

associated with standard, two-piece implant designs. Mini Implant Impression Copings, another

component of the Inclusive Mini Implant System, were snapped into place atop each O-ball abutment

(Fig. 8). Using a mouth mirror to help guide insertion, the custom tray was tried in to ensure ample room

for the impression copings.

Border molding was performed by filling first one side of the custom tray with Adaptol ® impression material

(J.F. Jelenko & Co.; New York, N.Y.) that had been heated in a warm water bath at 120 to 125 degrees

Fahrenheit (Fig. 9). The patient was guided through a series of movements that exercised the muscles of

mastication to create a highly accurate natural border along that half-arch (Fig. 10). The border mold on that

side was cooled in ice water for approximately one minute and then dried with compressed air. Heated

Adaptol was then placed in the other side of the tray, and the border molding process repeated for that half

of the arch (Fig. 11). Minor adjustments were made as needed by warming one side at a time, keeping the

other side cool to avoid unwanted movement. Border molding is a key step toward ensuring proper fit and

function of the prosthesis itself, which will maximize patient comfort and reduce stress on the implants.

After cooling and drying, excess Adaptol material was trimmed away from the intaglio surface of the

border mold with a very sharp Bard-Parker surgical blade (Aspen Surgical Products; Grand Rapids, Mich.)

– Clinical Case Report: Delivery of a Mini Implant-Retained Mandibular Overdenture – 39


Figure 12: Excess border material trimmed

Figure 13: PVS adhesive applied to custom tray

Figure 14: Impression material placed around implants

Figure 15: Final impression with impression copings

The impression was allowed to set in the mouth for four minutes, picking up the four

impression copings upon removal.

(Fig. 12). Duller blades may chip the border mold and should be avoided. The finished mold was cooled and dried again,

prior to the application of adhesive on the intaglio surface of the custom tray and the Adaptol border, to ensure adhesion of

the polyvinyl siloxane (PVS) impression material to both the border and tray (Fig. 13). This adhesive was allowed to set for

seven minutes. Light-bodied PVS impression material was then placed around the implants, making sure not to place any

of the material over the undercut areas of the impression copings (Fig. 14). The impression was allowed to set in the mouth

for four minutes, picking up the four impression copings upon removal (Fig. 15). The overall quality of the impression was

deemed excellent, having captured all of the borders and necessary anatomical landmarks. The impression was then sent

to the lab for the insertion of Inclusive Mini Implant Analogs and pouring of the master cast.

Third Prosthetic Appointment: Wax Rim Try-in

With a mandibular wax occlusion rim (also known as a bite block) and master cast of her lower arch (complete with

silicone-based soft tissue insert) (Fig. 16), the patient returned for jaw relation records, including vertical dimension of

occlusion (VDO), centric relation and centric registration. The wax rim contained a pair of attachments to snap onto the

patient’s distal implants, for stability during the relation processes (Fig. 17). The patient’s existing treatment dentures were

used as a baseline measurement.

A dot was placed on the patient’s nose and chin with an indelible marker. The patient was asked to lick her lips, swallow,

and then close her jaw, teeth biting together gently. The distance between the two dots was measured, and the process

repeated, to verify that the measured VDO was consistent (Fig. 18). The process was repeated yet again, but this time the

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Figure 16: Wax rim delivered on cast model

Figure 17: Intaglio surface of the wax rim with distal implant attachments

Figure 18: VDO measurement

Figure 19: Reducing vertical height of the wax rim

Figure 20: Notching the wax rim for bite registration

Figure 21: Injecting PVS bite registration material

patient was asked to relax her jaw, keeping her teeth apart, in order to measure the vertical dimension at

rest (VDR). Spoken “s” sounds (i.e., “Mississippi” and “sixty-six”) revealed a 1 to 2 mm freeway space, or

rest position. It is important not to coerce or guide the patient too much, as this can result in unnatural

movements and inaccurate measurements. The locked guide was set aside to save the measurement.

The treatment denture was removed and the wax occlusion rim inserted over the implants. A vertical opening

of 5 mm was observed. A heated wax spatula was then used to decrease the height of the occlusal wax

rim, maintaining the accuracy of the occlusal plane in reference to the existing maxillary denture (Fig. 19).

The wax was removed gradually, with multiple try-ins, to avoid having to go back and add wax, which is

much more difficult than wax removal. When the proper vertical height was established, a Bard-Parker surgical

blade was used to notch the occlusion rim, and PVS occlusal registration material injected (Figs. 20, 21).

– Clinical Case Report: Delivery of a Mini Implant-Retained Mandibular Overdenture – 41


Figure 22: Captured bite registration

Figure 23: Selecting tooth shade

Figure 24: Measuring the mesiodistal posterior space

Figure 25: Taking a new bite registration to demonstrate desired centric relation

The mandible was relaxed by mandibular manipulation to ensure a repeatable centric position. The PVS material was

allowed to set for two minutes, resulting in a proper bite registration with the teeth in place at the correct VDO (Fig. 22).

A natural tooth shade was selected and verified, using the teeth set in the treatment denture as a guide

(Fig. 23). The desired tooth mould was then selected, again using the existing denture as a reference. A Boley gauge was

used to measure the posterior area to help decide the number of teeth to be used (Fig. 24). In this case, four teeth were

chosen for the distal progression in order to cover the retromolar pads and provide a nice permanent stop in the posterior,

matching the design of the maxillary prosthesis.

Fourth Prosthetic Appointment: Wax Denture Try-in

Using the relation records and tooth selections (shade and mould) from the wax try-in, the lab fabricated and delivered a

trial denture with teeth set in wax, mounted on an adjustable articulator. Before authorizing final processing of the denture

in acrylic, the patient returned to the office for a try-in of the trial setup for evaluation of esthetics, phonetics, centric relation,

VDO, tooth shade and arrangement.

It was quickly discovered that the teeth were arranged in a standard, Class I occlusion. However, it was decided to recreate

the patient’s existing Class II occlusion, in deference to the moderate bone loss that gave her jaw a mildly distended appearance.

Keeping the Class I arrangement, with the teeth too far facial, would result in a pouty lower lip, sometimes referred

to as the “George Washington” look (as seen on a U.S. one-dollar bill). Speaking function was also deemed better served by

the desired Class II, with the teeth positioned more lingually.

The anterior teeth needed to be pushed back at least 2 mm, especially on the left side. A chairside adjustment with Bunsen

burner and spatula would necessitate keeping the patient in the chair for an hour or more, so the decision was made to

send the case back to the lab. To transmit the desired information, a new bite registration was taken, demonstrating desired

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Figure 26: Articulated model with bite registration and laboratory prescription

Figure 27: Evaluating occlusion, phonetics and esthetics

Figure 28: Comparison of provisional and final prostheses

Figure 29: Examining implant heads for cleanliness

centric relation (Fig. 25). With this and the cast of the existing prosthesis, the laboratory technician can

mount the information on an articulator and precisely determine the changes to be made (Fig. 26).

The follow-up try-in appointment revealed a prosthesis with excellent occlusion, phonetics and esthetics

(Fig. 27). By properly providing the lab technician with the necessary information (i.e., cast, centric relation

record and detailed prescription) upon the first try-in, further try-in appointments were avoided.

Delivery Appointment

Final delivery of the lab-fabricated Inclusive Mini Implant Overdenture commenced with a demonstration of

the connection between the implant analogs seated on the cast and the O-ring attachments housed within

the prosthesis, so that the patient could hear the snapping sound indicating a proper, retentive fit.

The patient’s existing denture was then removed for a side-by-side comparison (Fig. 28). The new overdenture

exhibited a much cleaner look, without the transitional soft liner. Of particular note in the new

prosthesis was the reduced size of the lingual flange extensions. While the patient had a lateral throat form

conducive to such extensions, they were no longer needed because the retention provided by the O-ring

attachments is far greater than that provided by any traditional denture modification.

The patient’s implants were examined for cleanliness, which is critical to ensuring a proper, retentive fit

(Fig. 29). Minor amounts of plaque and calculus were removed with a plastic scaling instrument. The patient

was then shown how to fit the prosthesis in her mouth, sliding it gently into position, with the attachments

aligned over the implant abutments. Once in position, two fingers were used to apply downward pressure

upon the anterior laterals of the prosthesis. A patient should never “bite” the overdenture into place, as this

can cause unnecessary wear on the O-rings.

– Clinical Case Report: Delivery of a Mini Implant-Retained Mandibular Overdenture – 43


Figure 30: Evaluating phonetics and occlusion

Figure 31: Verifying bilateral balancing occlusion

Figure 32: Marking sore spots

Figure 33: Relieving denture to eliminate patient soreness

Figure 34: Postoperative CBCT scan showing mini implant placement

Figure 35: Delivery of final prosthesis

With the overdenture fully seated, the borders were inspected for proper alignment. Phonetics and occlusion were also

evaluated (Fig. 30), using excursive movements to ensure bilateral balancing occlusion (Fig. 31). Centric relation marks were

very close, with heavy marks on the posteriors and light marks on the four anteriors. While it is important not to overload

the implants with pressure on the anteriors, there should be sufficient support to permit proper function. Excessive pressure

on the patient’s upper denture in the anterior section could result in “combination syndrome,” marked by premaxillary

resorption.

The patient was asked to wait 10 minutes to allow for the manifestation of any sore spots. Two areas of tissue irritation were

noted. The affected areas were marked for transfer to the prosthesis (Fig. 32). Relief of the marked areas was performed

chairside with a carbide bur (Fig. 33), trimming away just enough acrylic to relieve the sore spot, after which the overdenture

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Implant-retained overdentures can offer dramatic improvement in form and function,

and small-diameter implants can prove an ideal treatment option when conventional

implants are contraindicated due to medical, anatomical or

financial reasons.

was cleaned and placed back in the mouth. The patient was

encouraged to remove and reinsert the prosthesis herself. She

did so without any pain or discomfort.

Occlusion and phonetics were checked anew, as relieving the denture

will cause it to settle a little bit in those areas that were previously too high.

Both were deemed satisfactory. Esthetics were similarly pleasing, consisting of

a nice maxillary overlap so that the lower teeth did not look too bulky, avoiding the

unsightly “bulldog” or “George Washington” look.

Figures 34 and 35 illustrate the desired surgical outcome and final prosthetic outcome. The

patient was asked to return the next day for a follow-up to check for any new sore spots. She

was further asked to limit herself, initially, to softer, easy-to-chew foods while acclimating to her new

prosthetic reality. Though accustomed to cutting up her food, the patient was told she should no longer

have to do so, due to the superior retention provided by the implant attachments. She was encouraged to

keep her old, soft-lined denture as a backup prosthesis. A home care cleaning kit and instructions were

provided for use with both the primary and backup dentures. In-office visits for ultrasonic cleaning of the

prostheses were recommended every three months. When provided with a denture adhesive for use with

her traditional maxillary denture, she was quite happy to receive confirmation that traditional adhesive

would no longer be needed for her mandibular overdenture.

Summary

Traditional dentures have long been a source of frustration and discomfort for users, particularly in the

edentulous mandible, where even simple, everyday oral movements may dislodge the prosthesis. Implantretained

overdentures can offer dramatic improvement in form and function, and small-diameter implants

can prove an ideal treatment option when conventional implants are contraindicated due to medical, anatomical

or financial reasons. The ultimate solution, however, is still highly dependent upon proper delivery

and adjustment of the final prosthesis. Whether utilizing the patient’s existing denture or providing a new

one, establishing ideal fit, balance, occlusion, and overall patient comfort will help to maximize the shortand

long-term success of any implant-retained removable solution. IM

References

1. Landesman HM. A technique for the delivery of complete dentures. J Prosthet Dent. 1980 Mar;43(3):348-51.

2. Ganz SD. CT scan technology: an evolving tool for avoiding complications and achieving predictable implant placement and restoration. Int

Mag Oral Implant. 2001;1:6-13.

3. Marchack CB. An immediately loaded CAD/CAM-guided definitive prosthesis: a clinical report. J Prosthetic Dent. 2005 Jan;93(1):8-12.

4. Lott F, Levin B. Flange technique: an anatomic and physiologic approach to increased retention, function, comfort, and appearance of dentures.

J Prosthet Dent. 1966 May-Jun;16(3):394-413.

– Clinical Case Report: Delivery of a Mini Implant-Retained Mandibular Overdenture – 45


Implant and Mandibular Canal Mapping

by James Jesse, DDS

As the saying goes, “The only constant in life

is change.” This is certainly true of the dental

industry, as emerging technologies continue to transform

the everyday methods clinicians use to treat their patients.

Fortunately, the purpose of these technologies is to

improve the quality of care by making treatments safer,

more accurate, more efficient and more cost-effective

overall. Whatever the short-term cost in terms of monetary

or educational investment, the long-term adoption of new

technologies is designed to better our lives as dentists,

and those of our patients.

With 3-D imaging, we now can open the

door and examine dental anatomy from any

direction or angle, which gives us much

more accurate information before we even

begin treatment, enabling us to continually

improve the quality of our work.

The purpose of these technologies is to

improve the quality of care by making

treatments safer, more accurate, more

efficient and more cost-effective overall.

In the diagnostic realm of dentistry, the X-ray has

evolved from 30-plus seconds of exposure to digital,

where the exposure is fractions of a second. We have

seen the panographic films change to digital, showing

better detail and clarity. It is logical to now include 3-D

imaging into the dental practice. With traditional 2-D

images, the dental practitioner is limited to what information

can be seen in that dimension, i.e. buccal-lingual

views from panoramic, periapical and bitewing X-rays.

With 3-D imaging, we now can open the door and

examine dental anatomy from any direction or angle,

which gives us much more accurate information before

we even begin treatment, enabling us to continually

improve the quality of our work.

Three-dimensional Cone Beam Computed Tomography

(CBCT) images have a wide range of diagnostic and

treatment planning uses, including general dentistry,

TMJ analysis, airway studies (snoring and sleep apnea),

jaw and other tumors, impacted teeth, periodontal

disease, endodontic anomalies, and oral surgery. One

area in which 3-D CBCT images are quickly becoming a

standard-of-care practice is in implant planning.

CASE REPORT

In April 2011, a 55-year-old patient with a lifelong history

of serious dental problems presented for a dental

implant in the area of tooth #29. Due to this patient’s

history, it was critical to fully understand her anatomy

— the location of her mandibular canal and mental

foramina, bone structure and bone density — to verify

that she had sufficient bone to support an implant. A

Figure 1: Preoperative CBCT panographic image

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Figure 2: Sagittal MPR view with mapped canal

Figure 3: Sagittal view with vertical measurements

Due to this patient’s history, it was critical

to fully understand her anatomy — the

location of her mandibular canal and

mental foramina, bone structure and

bone density — to verify that she had

sufficient bone to support an implant.

3-D CBCT scan was taken using the PreXion 3D CBCT

dental scanner (PreXion Inc.; San Mateo, Calif.) and a

thorough evaluation performed. The first step in this

evaluation was to examine the panographic image produced

by the CBCT system to get an overall perspective

of the patient’s anatomy (Fig. 1).

A more comprehensive examination was performed

using the multiplanar reconstruction (MPR) and threedimensional

views. In the sagittal (side) view, the

mandibular canal was easily identified and mapped to

pinpoint its precise location and avoid potential problems

(Fig. 2). Measurements were taken to determine

Figure 4: Coronal view with width and length measurements

the vertical distance from the ridge crest to the nerve

below, thereby determining the maximum length of

implant that could be used while allowing for sufficient

margin to avoid hitting or damaging the alveolar nerve

(Fig. 3). Bone density was also measured and found

to be in good condition where the implant was to be

anchored. The examination was continued in the coronal

view (front to back), and additional measurements

were taken to determine the bone width and also to

reaffirm the distance from the ridge to the mandibular

canal (Fig. 4).

– Implant and Mandibular Canal Mapping – 47


It was determined from these highly accurate images

and measurements that there was sufficient bone and

bone density to allow for placement of a 3.75 x 13 mm

implant and still have a 3 mm-plus margin for error.

The CBCT images also revealed that tooth #31 was

cracked, and thus this tooth was extracted prior to

implant placement.

CONCLUSION

A few months postoperative, a follow-up CBCT scan was

conducted and measurements taken to confirm proper

implant placement and osseointegration (Figs. 5, 6).

The advent of affordable, high-quality 3-D CBCT

systems in dentistry has definitely improved our

ability to better and more accurately diagnose and

treatment plan. While there are significant financial

benefits to having a cone beam system in your practice,

These 3-D CBCT systems allow us

to confidently know and understand

our patients’ anatomy and to identify

potential complications before we begin

treatment, thus producing safer,

more predictable outcomes.

more critical is the quality and quantity of information

provided to us by these systems. These 3-D CBCT

systems allow us to confidently know and understand

our patients’ anatomy and to identify potential complications

before we begin treatment, thus producing

safer, more predictable outcomes. IM

Figure 5: Postoperative sagittal view with measurements

Figure 6: Postoperative panoramic view with implant in place

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Understanding Zirconia Crown Esthetics

and Optical Properties

Go online for

in-depth content

by Ken Knapp

Introduction

Today’s state-of-the-art esthetic restorative crown & bridge

materials consist of monolithic ceramics such as zirconia

(ceramic) and lithium disilicate (glass-ceramic). Monolithic

ceramic restorations made of partially stabilized zirconia

(typically 3 percent yttria, 97 percent zirconia, by

weight) are increasingly being used as an alternative to

traditional PFM restorations and other porcelain-veneered

ceramic substructures, such as porcelain-veneered zirconia

frameworks. When compared to other all-ceramic crown

& bridge materials, monolithic zirconia exhibits a unique

combination of high flexural strength, fracture toughness,

and toothlike esthetics that is redefining what constitutes

a reliable and esthetic ceramic crown & bridge material

(Fig. 1). Moreover, advanced CAD/CAM manufacturing

technology provides for a cost-effective alternative to conventional

PFM and full-cast restorations.

BruxZir ® Solid Zirconia, the monolithic nanocrystalline zirconia

material developed by Glidewell Laboratories, has helped

to revolutionize crown & bridge manufacturing technology

and set a new benchmark for esthetic monolithic ceramics.

According to Robin Carden, senior director of research and

development at the lab, “BruxZir Solid Zirconia … represents

the state-of-the-art all-ceramic crown & bridge material, with

its unique combination of toothlike esthetics and superior

mechanical reliability.” BruxZir Solid Zirconia is helping to

usher in a new age of biomimetic dental materials that are

being engineered to emulate the optical, mechanical and

biological characteristics and integrity of natural dentition.

The future of dental restorative materials will be newly engineered

nanostructures and nanocrystalline materials that

replicate the esthetics, reliability and biological function of

naturally occurring tooth structure.

Material

Flexural Strength (MPa)/

K1C (MNm-3/2)

Optical Transmission/

Refractive Index

Composition

Dental enamel

NA

0.6–1.8

53%

1.66 @ 550 nm, 1 mm thickness

96 wt.% inorganic calcium phosphate,

4 wt.% organic and water

Dentin

Na

3.1

Na

NA

70 wt.% inorganic calcium phosphate,

30 wt.% organic and water

Leucite-reinforced

feldspathic

porcelain

140

2.6

55%

1.50 @ 550 nm, 1.25 mm thickness

Leucite crystalline phase within glass matrix

(KOAl 2

O 3

4SiO 2

)

Silica glassy amorphous matrix 60–70%.

Lithium disilicate 400

3.3

47%

~1.55 @ 550 nm, 1.25 mm thickness

Lithium silicate crystals Li 2

Si 2

O 5

(70% crystalline)

BruxZir ® Solid

Zirconia

1400

7

42.5%

2.20 @ 550 nm, 1.25 mm thickness

Yttria-zirconia, partially stabilized

(100% crystalline)

Figure 1: A material properties comparison of BruxZir Solid Zirconia with other all-ceramic crown & bridge materials and naturally occurring tooth structure

50

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Scientific Principles of Optical Esthetics

Restorative dentistry involves repairing and replacing natural

tooth structure, dentin and enamel with crowns & bridges

fabricated from man-made materials with machine-generated

anatomy, while minimizing perturbation or alteration of the

mechanical function, reliability and esthetics of natural tooth

structures. A primary objective of engineering and manufacturing

dental restorative ceramic materials, then, is to mimic

the optical properties of natural dentition. For this purpose, an

understanding of the fundamental structure and optical properties

of tooth enamel and dentin is paramount, along with a

thorough knowledge of scientific principles pertaining to the

study of light (electromagnetic radiation) and its interaction

with biomimetic dental materials.

Organic Structure

The intrinsic optical properties and characterization of natural

dentition enamel and dentin is limited to date. Synthetic crown

& bridge restorations generally replace the entire enamel layer

(which is approximately 1.5 mm thick, depending on factors

such as tooth location) and part of the dentin. 1 Natural tooth

enamel is considered optically transparent, in that it transmits

approximately 50 percent of the light it encounters (Fig. 2).

Enamel is comprised of inorganic calcium phosphate (96

weight percent) and organic molecules and water (4 weight

percent). 2–7 The calcium phosphate crystals function as optical

nanoprisms that are approximately 26 nm in diameter and

about 100–1000 nm long, formed into columnar structures

called nanorods. 2–4 These structures are aligned and parallel

to one another, oriented with the nanorod’s long axis perpendicular

to the outer surface of the tooth. Due to its structure

and composition, enamel calcium phosphate nanorod material

exhibits a unique, optical light-guiding effect. Figure 3 shows

a cross section of a natural molar. When compared to enamel,

the underlying dentin structure consists of a decreased

ratio of inorganic calcium phosphate (70 weight percent)

to organic molecules and water (30 weight percent).

Optical Terminology

Standardized language used by dentists and dental technicians

to describe the esthetics of dental material include the optical

properties of hue, value, chroma, translucency and opacity.

Hue (see Glossary, page 53) is the color or dominant wavelength

in the visible electromagnetic spectrum (400–700 nm)

of a material (Fig. 4). Value is the brightness level, where

white is assigned a higher value and black is assigned a lower

value. 8,9 Chroma is the intensity of hue or color. In 1931, the

Commission Internationale de l’Eclairage (International Commission

on Illumination, or CIE) formulated a standardized

colorimetry system by which to better quantify and physically

describe the human color perception. 10 Hue, value and chroma

terms are used by the CIE 1976 (L*, a*, b*) color space system

(more commonly known as CIELAB), based on measurements

made on a spectrophotometer. Translucency is the amount

of light that transmits through a material, and opacity is the

lack of light transmitting through a material.

Figure 2: Optical transmission of tooth enamel, 1 mm thick

Nanorod structures

Figure 3: Optical image of a human molar

Figure 4: Electromagnetic spectrum

Enamel

Dentin

– Understanding Zirconia Crown Esthetics and Optical Properties – 51


Spectrophotometry

A spectrophotometer (Fig. 5) is a sophisticated analytical

optical instrument consisting of a stable and precise

light source and light detector (photo detector) capable of

measuring discrete colors or wavelengths with a 1 nm resolution

measured between the ultraviolet and infrared wavelengths

within the visible light spectrum. True colors, shades

and optical properties can be reproducibly quantified by a

spectrophotometer, which engineers and scientists use to

characterize optical ceramic and dental ceramic materials

by measuring the transmission, reflection and absorption of

light as a function of wavelength. The latest digital dental

shade-taking systems use a simplified spectrophotometer to

quantify tooth shades.

Determining Shade

Ceramic crown & bridge restorations are fabricated to the

desired shade and esthetic detail based typically on a standardized

shade guide system, such as the VITA Classical

Shade Guide or VITA 3D-Master Shade Guide. The VITA

Classical Shade Guide was introduced in 1956 and is considered

the gold standard for dental tooth shade quantification.

This guide classifies dental shades into 16 different shade

guide tabs. The VITA 3D-Master Shade Guide introduced

in the 1990s is based on the earlier Munsell color space

and the CIELAB colorimetry system. The VITA 3D-Master

Shade Guide tabs are categorized by value, hue and chroma

colorimetry parameters. The dentist and dental laboratory

technician use the shade guide tabs to determine the appropriate

tooth shade by visually comparing the shade guide

tabs against the patient’s tooth and against the ceramic

dental restoration — in ambient background lighting. This

method, although common, is inherently subjective, dependent

on myriad variations arising from ambient

light interactions and color sensitivity of the

human eye.

Figure 5: PerkinElmer Lambda 35 UV/VIS

Spectrophotometer with Labsphere RSA-PE-20

Reflectance Spectroscopy Accessory

Color and the Human Eye

The eye detects three primary colors: red, green and blue.

The optical focal plane is the retina, which contains two

kinds of light detection sites: rods and cones. Rods make

up the majority of light sensors in the retina. They are extremely

sensitive to light intensity variation, but are not

color-sensitive. Cones are sensitive to specific colors — or

rather the electromagnetic wavelengths that are responsible

for color vision. Cones consist of three primary lengths

attuned to specific colors or wavelengths: long (L-cones),

medium (M-cones) and short (S-cones). L-cones detect red

colors at a peak wavelength of 565 nm, while M-cones

detect green colors at a peak of 540 nm and S-cones

detect blue colors at a peak of 440 nm. The majority of

these retinal cones are of the long and medium variety.

The superpositioning of the three different color signals

results in a peak sensitivity to light wavelength at 550 nm.

The human brain can perceive the continuum of visible

colors between blue (the shortest wavelength the retina

is sensitive to at 400 nm) and red (the longest light wavelength

the retina is sensitive to at 700 nm). Except for red,

green and blue, color is a perception, a result of the brain

processing the additive intensities of the three primary

colors detected by the cones.

Visible Light and the

Electromagnetic Spectrum

The color-related esthetics of natural dentition and dental

ceramic materials result from the interaction of light

with the material in the visible part of the electromagnetic

spectrum (400–700 nm). This visible range, of course,

represents only a small portion of the larger electromagnetic

spectrum, which includes ultraviolet rays, X-rays,

and gamma rays smaller than 400 nm in wavelength; and

near-infrared, infrared, microwaves, radio waves, and longwaves

larger than 700 nm in wavelength (Fig. 4). Wavelengths

that fall within the visible electromagnetic spectrum

are expressed in nanometer units, where 1 nm equals

one billionth of a meter (1 nm=1x10 -9 m). Expressed in

colors, the visible electromagnetic spectrum ranges from

violet (400 nm) to red (700 nm). As described earlier, the

human eye is most sensitive to the yellow-orange color

at a wavelength of 550 nm.

Dielectrics

Dental ceramic materials such as veneering porcelains

and alumina/zirconia crown & bridge frameworks are

electrically insulating materials commonly known

as dielectrics. Dielectric materials are generally

comprised of inorganic oxides, such as silicon

dioxide (SiO 2

), zirconium dioxide (ZrO 2

), titanium

dioxide (TiO 2

) and many others. Additionally,

the calcium phosphate of natural dentition and

polymer materials such as composites are typically

dielectrics consisting also of inorganic nitrides and

some carbides.

52

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Refraction and Permittivity

The refractive index (n) of a material can be defined as the

ratio of the speed of light (c) propagating in a vacuum to the

velocity of light (v) propagating in that material, expressed

as n=c/v. l1 The refractive index is a function of permittivity,

which is the measure of the resistance that is encountered

when forming an electric field in a medium. More

specifically, permittivity is determined by a material’s ability

to polarize in an applied alternating electric field. Dielectric

materials are susceptible to this polarization from the

electric field component of the propagating electromagnetic

waves. The relative permittivity (ε r ) of a dielectric material

is determined by its composition, crystal structure and the

applied electromagnetic field wavelength or frequency. In

nonmagnetic dielectric materials, the refractive index is

equal to the square root of its relative permittivity (expressed

as n= ε r ). 12 The index of refraction for some common dental

materials can be compared to that of natural dentition in

Figure 1.

Transmission vs. Reflection

When visible light interacts with dielectric dentition and

dental ceramic materials, wavelengths are either transmitted,

reflected or absorbed, the sum of these values equaling

the incident light source energy. This can be expressed as

1=T+R+A, where T is the value of transmission, R is the value

of reflection and A is the value of absorption. A schematic

of optical material-light interaction is shown in Figure 6.

The optical esthetics of dental ceramics are based on the

wavelength dependence of light reflected from the ceramic

restoration and the depth perception of transmitted light.

An observer’s eye will see light reflected from the ceramic.

This reflected light is comprised of first (initial) surface

reflection, and also light partially transmitting from the dental

ceramic and reflecting from a second interface or lightscattering

surface. Additionally, backlighting of the ceramic

is transmitted through the material. The observer’s visual

perception is based on the summation of these optical reflections

and transmissions that result from interaction with

the restorative ceramic material.

Light Interaction in Dielectric Materials

The wavelength dependence of light interaction with dielectric

materials is a complex phenomenon. Light-dielectric material

interaction ranges from light scattering from material

porosity on the order of the effective wavelength (Mie theory)

to quantum mechanical interaction with light and the crystalline

order and atomic structure of the ceramic. 12–18 Additionally,

light scattering caused by birefringence (double refraction)

is the driving force behind recent research into optically

transparent nanocrystalline ceramic materials. Birefringence

is caused by anisotropic crystalline index of refraction, as

found in non-symmetric crystal structures — typically noncubic

or strained. This results in the refractive index being

different for various crystallographic plane orientations

with respect to the direction of light propagation (Fig. 7).

Figure 6: Optical material schematic

Crystal orientation 2

Crystal orientation 3

Crystal orientation 4

Crystal orientation 1

Figure 7: Birefringence light-scattering model

Hue – A color, as it corresponds to

the dominant wavelength in the visible

electromagnetic spectrum.

Value – A level of brightness, ranging

from black (low value) to white (high

value).

Chroma – The intensity or purity of

a color, combining hue and saturation.

Translucency – The amount of light

that transmits through a material.

Opacity – The lack of light transmitting

through a material.

Spectrophotometry – Measuring

the relative intensities of light in different

parts of a spectrum.

Superpositioning – A principle

stating that, for all linear systems,

the net response at a given place and

Glossary

Light scattering

caused by different

indexes of refraction

from different zirconia

crystal orientations

time caused by two or more stimuli is

the sum of the responses that would

have been caused by each stimulus

individually.

Dielectric – A nonconductor of

direct electric current.

Refractive Index – The ratio of

the speed of light (electromagnetic

radiation) in a vacuum to the velocity

of light in another medium (material).

Permittivity – The ability of a material

to store electrical potential energy

under the influence of an electric field.

Birefringence – The refraction of

light in an anisotropic material in two

slightly different directions to form

two rays.

Anisotropic – Having unequal physical

properties along different axes.

– Understanding Zirconia Crown Esthetics and Optical Properties – 53


The key to increasing light transmission in materials such as

zirconia, then, is to reduce the crystalline grain size, thereby

reducing birefringent light scattering and increasing transmission.

Restorative Ceramic Materials of Today

There are primarily three different types of esthetic dental

ceramic materials used today for crown & bridge restorations:

glassy phase porcelains used in veneering, glassceramics

such as lithium disilicate, and ceramics such as

zirconia and alumina.

Glassy Phase Porcelains

Materials comprised of mainly glassy silica in the amorphous

solid state (glassy matrix) make up the majority of

the dental ceramics used today. Glassy phase veneering

porcelains and pressable ceramics over substructures typically

consist of glassy matrix feldspathic material with a leucite

crystal phase. Typically, feldspathic leucite-reinforced

glassy materials consist mainly of an amorphous silica phase

(approximately 70 weight percent amorphous silica). The

glassy phase veneering porcelains have been used for more

than 30 years, and have become the benchmark for esthetics

in dental restorations. These are typically used as the esthetic

layer over substructures. Their low flexural strength and

fracture toughness limit their indication to veneering layers,

inlays and onlays (Fig. 1). However, glassy phase porcelains

have the most esthetic optical properties in terms of simulating

the optical transmission and color of natural dentition,

due largely to the fact that these materials have the highest

optical transmission when compared to other restorative

ceramic materials (Fig. 8).

Glass Ceramics

Lithium disilicate glass-ceramics are approximately 30

weight percent amorphous silica and 70 weight percent

crystalline lithium disilicate crystals, as shown via scanning

electron microscopy (Fig. 9). These glass-ceramics are typically

used for pressable all-ceramic crowns and monolithic

ceramic CAD/CAM crown restorations. The optical transmission

and resulting esthetics of shaded lithium disilicate are

currently the benchmark for esthetic monolithic CAD/CAM

ceramic crowns (Fig. 8). However, the flexural strength and

fracture toughness limit their indication to single crown restorations

(Fig. 1).

Ceramics

Zirconia and alumina dental ceramic materials are typically

comprised of a nearly 100 weight percent crystalline phase,

as shown via scanning electron microscopy (Fig. 10). These

ceramics have been used in dentistry for the last 15 years

due to their high flexural strength and fracture toughness

(Fig. 1). The indications for partially stabilized tetragonal

zirconia range from single crown restorations to full-arch

frameworks, due to the material’s unique blend of strength

and color when compared to other crystalline dental ceramics.

The limitation to date has been that zirconia tends to

have a higher opacity, which would seem to contraindicate

use in the esthetic zone. Nevertheless, recent advances in

zirconia ceramic processing technology have resulted in

highly popular monolithic crown & bridge products, prescribed

for use primarily in the posterior tooth region, and

strides have been made to improve the material’s esthetic

qualities. BruxZir Solid Zirconia, for example, which undergoes

a unique, colloidal processing technique (patent pending),

has been shown to exhibit improved optical transmission

compared to zirconia that has undergone conventional

processing such as cold isostatic pressing (CIP) (Figs. 11, 12).

The Future of Zirconia Restorations

Ongoing advances in zirconia processing technology are resulting

in dramatically improved zirconia esthetics, which in

turn has caused a paradigm shift in CAD/CAM all-ceramic

crown & bridge restoration materials and technology.

Figure 9: Lithium disilicate SEM image

Figure 8: Optical transmission of common dental ceramics, 1.25 mm thick

Figure 10: BruxZir Solid Zirconia SEM image

54

– www.inclusivemagazine.com –


The intrinsic physical limit for toothlike optical transmission

of tetragonal zirconia is currently within reach. The

theoretical optical transmission limit of tetragonal zirconia

is governed by birefringence as a result of grain or crystal

size. The optical transmission of tetragonal zirconia is

increased exponentially as the sintered grain size is reduced

(Fig. 13). 13,14 Toward this end, the research and development

team at Glidewell Laboratories is among those

known to be leading the effort to develop sub-50 nm crystalline

sintered zirconia by developing sub-4 nm crystal

zirconia starting powder.

As it appears today, crown & bridge restorations with toothlike

esthetics created from monolithic tetragonal zirconia are

the future of dental restorations. The inherent mechanical

strength and reliability of tetragonal zirconia, along with

the continued development of more natural, toothlike esthetics,

will make monolithic zirconia a dominant choice for

the majority of crown & bridge restorations, expanding from

the posterior tooth region to crowns, bridges and veneers

placed in the anterior esthetic zone. IM

References

1. Smith TM, Olejniczak AJ, Reid DJ, Ferrell RJ, Hublin JJ. Modern human

molar enamel thickness and enamel-dentine junction shape. Arch Oral Biol. 2006

Nov;51(11):974-95.

2. Hannig M, Hannig C. Nanomaterials in preventive dentistry. Nat Nanotechnol. 2010

Aug;5(8):565-9.

3. Uskokovic V, Bertassoni LE. Nanotechnology in dental sciences: moving towards a

finer way of doing dentistry. Materials. 2010;3(3):1674-1691.

4. Gutierrez-Salazar MP, Reyes-Gasga J. Microhardness and chemical composition of

human tooth. Mat Res. 2003;6(3):367-73.

5. Marshall GW Jr, Marshall SJ, Kinney JH, Balooch M. The dentin substrate: structure

and properties related to bonding. J Dent. 1997 Nov;25(6)441-58.

6. Brodbelt RH, O’Brien WJ, Fan PL, Frazer-Dib JG, Yu R. Translucency of human

dental enamel. J Dent Res. 1981 Oct;60(10):1749-53.

7. Xiong F, Chao Y, Zhu Z. Translucency of newly extracted maxillary central incisors at

nine locations. J Prosthet Dent. 2008 Jul;100(1):11-7.

8. Anusavice KJ, ed. Phillips’ Science of Dental Materials. 11th ed. St. Louis:

WB Saunders; 2003.

9. Craig RG, Powers JM, eds. Restorative Dental Materials. 11th ed. St. Louis:

Mosby Inc; 2002.

10. Paravina RD. Color in dentistry: is “everything we know” really so? Inside Dental

Assisting. 2010 Jun;6(6) Suppl:10-19.

11. Wangness RK. Electromagnetic Fields. 2nd ed. Canada: John Wiley & Sons; 1986,

pg 378.

12. Alaniz JE, Perez-Gutierrez FG, Aguilar G, Garay JE. Optical properties of transparent

nanocrystalline yttria stabilized zirconia. Opt Mater. 2009 Nov;32(1):62-8.

13. Krell A, Klimke J, Hutzler T. Transparent compact ceramics: inherent physical

issues. Optical Materials. 2009 Jun;31(8):1140-50.

14. Klimke J, Trunec M, Krell A. Transparent tetragonal yttria-stabilized zirconia

ceramics: influence of scattering caused by birefringence. J Am Ceram Soc. 2011

Jun;94(6);1850-58.

15. Tsukuma K, Yamashita I, Kusunose T. Transparent 8 mol% Y2O3-ZrO2 (8Y) ceramics.

J Am Ceram Soc. 2008 Mar;91(3):813-18.

16. Apetz R, van Bruggen MPB. Transparent alumina: a light-scattering model.

J Am Ceram Soc. 2003 Mar;86(3):480-86.

17. Wood DL, Nassau K. Refractive index of cubic zirconia stabilized with yttria. Appl

Opt. 1982 Aug 15;21(16):2978-81.

18. Simmons JH, Potter KS. Optical Materials. San Diego: Academic Press; 2000.

Figure 11: Optical transmission of colloidal-processed BruxZir Solid Zirconia versus

that of zirconia that has undergone cold isostatic pressing (CIP), 1.25 mm thick

Figure 12: Optical properties of BruxZir Solid Zirconia, 1.25 mm thick

Figure 13: Theoretical optical transmission versus grain size of tetragonal zirconia,

1 mm thick

– Understanding Zirconia Crown Esthetics and Optical Properties – 55


Inclusive ® Image Contest: Name That Implant

How many implants can you identify? In the box beneath each radiograph, write the letter (A–J) corresponding to

the name of the implant pictured.

The microgrooves

and abutment connection

are clues.

Vents are unique.

Body shape and

thread pattern will

lead to the answer.

Thread pattern is

the giveaway.

The neck gives it

away.

Threads and apical

design are the

telling features.

No clues are

needed.

Can’t miss that

thread pattern.

No internal threads

are present.

Press-fit with

coronal grooves.

A. NobelActive - Internal Connection (Nobel Biocare)

B. Hexed-Head Press Fit Spike Universal (3M ESPE)

C. Sustain Cylinder External Hex (Keystone Dental)

D. Core-Vent (Zimmer Dental)

E. Tapered Internal (BioHorizons)

F. OsseoSpeed (Astra Tech Dental)

G. Hollow Cylinder (Straumann)

H. NanoTite Tapered Prevail (Biomet 3i)

I. NobelReplace Tapered (Nobel Biocare)

J. Screw-Vent (Zimmer Dental)

To submit your answers, tear out this page and send it to:

Glidewell Laboratories

Attn: Inclusive magazine

4141 MacArthur Blvd.

Newport Beach, CA 92660

Or scan your entry and e-mail it to

inclusive@glidewelldental.com

The first 100 correct entries received will each be awarded $100 in Glidewell lab credit good toward any implant-related product or service.

Entries must be received by Dec. 30, 2011. The results will be announced in the winter issue of Inclusive magazine.

Due to legibility issues, faxed entries will not be accepted. One entry per office. Participation grants Inclusive magazine permission to print

your name in a future issue or on its website.

________________________________________ _________________________________________ __________________________

Name City, State of Practice Phone

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