Restorative Driven Implant Solutions Vol. 2, Issue 4
A Multimedia Publication of Glidewell Laboratories • www.inclusivemagazine.com
From Intraoral Scan
to Final Custom
Dr. Perry Jones
Lab Corner: Accurately Seating
Inclusive Custom Abutments
Dzevad Ceranic, CDT
Delivering a Mini Implant
Dr. Christopher Travis
Mapping the Mandibular
Canal with CBCT
Dr. James Jesse
Esthetics and Optical
Properties of Zirconia
Research Scientist Ken Knapp
Dr. Michael McCracken
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
• Research scientist Ken Knapp explores the optical properties
of partially stabilized zirconia and its future as a leading dental
Check out the latest issue of Inclusive
magazine online or via your smartphone at
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 –
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
28 Lab Corner: Accurately Seating
Inclusive ® Custom Abutments Using
an Acrylic Jig
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
Jim Glidewell, CDT
Editor-in-Chief and clinical editor
Bradley C. Bockhorst, DMD
Jim Shuck; Mike Cash, CDT
Greg Minzenmayer; Dzevad Ceranic, CDT;
David Casper; Tim Torbenson
Eldon Thompson, Jennifer Holstein, David Frickman
digital marketing manager
Graphic Designers/Web Designers
Jamie Austin, Deb Evans, Joel Guerra,
Audrey Kame, Lindsey Lauria, Phil Nguyen,
Kelley Pelton, Melanie Solis, Ty Tran, Makara You
Sharon Dowd; James Kwasniewski, Marc Repaire,
Teri Arthur, Vivian Tsang
If you have questions, comments or suggestions, e-mail us at
email@example.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
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
– Letter from the Editor – 3
■ 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 firstname.lastname@example.org.
■ 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 email@example.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
■ 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@
■ 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 firstname.lastname@example.org.
■ 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
– www.inclusivemagazine.com –
■ 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
■ 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 email@example.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 firstname.lastname@example.org.
■ 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
■ 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 email@example.com.
– Contributors – 5
From Intraoral Scan to
Final Custom Implant Restoration
Go online for
by Perry E. Jones, DDS, FAGD
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.
– www.inclusivemagazine.com –
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).
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.
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
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
– www.inclusivemagazine.com –
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
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).
– www.inclusivemagazine.com –
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!
– www.inclusivemagazine.com –
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
• Baldissara P, Llukacej A, Ciocca L, Valandro FL, Scotti R. Translucency of zirconia
copings made with different CAD/CAM systems. J Prosthet Dent. 2010
• 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.
• 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:
• Jones PE. Cadent iTero optical scanning digital impressions for restorative and
invisalign. Dental Product Shopper. 2011 Jun 28 [cited 2011 Jul 29]. Available from:
• Kurbad A. Impression-free production techniques. Int J Comput Dent.2011;14(1):
• 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
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• Zweig A. Improving impressions: go digital! Dent Today. 2009 Nov;28(11):100, 102,
– From Intraoral Scan to Final Custom Implant Restoration – 13
An Interview with
Dr. Michael McCracken
Go online for
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
– 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
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
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
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
– www.inclusivemagazine.com –
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
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
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
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
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
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
BB: How many implants do you usually like to do for
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
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
to those of traditional
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.
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.
Several features of the
abutment were changed
during the design
optimization to increase
the strength of the zirconia
– 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.
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
Implant and abutment are in contact on the mating surface and
Implant and abutment are in contact on the mating surface and
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
– www.inclusivemagazine.com –
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.
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
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.
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
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
– www.inclusivemagazine.com –
Inclusive® Custom Abutments
Using an Acrylic Jig
Go online for
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
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
*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.
– www.inclusivemagazine.com –
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.
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
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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
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
Using the jig as a carrier, deliver the abutment to the
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
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.
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
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
Figures 17a, 17b: Seated screw-retained BruxZir crown
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
Go online for
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.
(4 days in lab)
(2 days in lab)
(2 days in lab)
(3 days in lab)
(5 days in lab)
(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.
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
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
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.
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
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.
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
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
by Ken Knapp
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.
Flexural Strength (MPa)/
1.66 @ 550 nm, 1 mm thickness
96 wt.% inorganic calcium phosphate,
4 wt.% organic and water
70 wt.% inorganic calcium phosphate,
30 wt.% organic and water
1.50 @ 550 nm, 1.25 mm thickness
Leucite crystalline phase within glass matrix
Silica glassy amorphous matrix 60–70%.
Lithium disilicate 400
~1.55 @ 550 nm, 1.25 mm thickness
Lithium silicate crystals Li 2
BruxZir ® Solid
2.20 @ 550 nm, 1.25 mm thickness
Yttria-zirconia, partially stabilized
Figure 1: A material properties comparison of BruxZir Solid Zirconia with other all-ceramic crown & bridge materials and naturally occurring tooth structure
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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.
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).
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
Figure 3: Optical image of a human molar
Figure 4: Electromagnetic spectrum
– Understanding Zirconia Crown Esthetics and Optical Properties – 51
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.
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
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
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.
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
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
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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
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
Value – A level of brightness, ranging
from black (low value) to white (high
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
caused by different
indexes of refraction
from different zirconia
time caused by two or more stimuli is
the sum of the responses that would
have been caused by each stimulus
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
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).
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
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
– 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
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
2. Hannig M, Hannig C. Nanomaterials in preventive dentistry. Nat Nanotechnol. 2010
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,
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
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.
and abutment connection
Vents are unique.
Body shape and
thread pattern will
lead to the answer.
Thread pattern is
The neck gives it
Threads and apical
design are the
No clues are
Can’t miss that
No internal threads
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:
Attn: Inclusive magazine
4141 MacArthur Blvd.
Newport Beach, CA 92660
Or scan your entry and e-mail it to
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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