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Journa
December 2019
Veneer Restorations
Bleaching Systems
Orthodontic Treatment
Osteonecrosis
Circadian Behaviors
C A L I F O R N I A D E N TA L A S S O C I AT I O N
Spotlight on Dental Student Research
Alice Goodwin, DDS, PhD, and
Kyle Jones, DDS, PhD
Vo l 47
N o9
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Dec. 2019 C D A J O U R N A L , V O L 4 7 , Nº 1 2
d e pa r t m e n t s
757 The Editor/Earworms and Merciful Acts
761 Letter to the Editor
763 Thank You to the 2019 Reviewers
765 Impressions
811 RM Matters/Reduce Risk, Increase Productivity
With Cellphone Policies
815 Regulatory Compliance/HIPAA Myths Explained 765
819 Ethics/How To Handle a Difficult Situation
822 Tech Trends
f e at u r e s
769 Spotlight on Dental Student Research
An introduction to the issue.
Alice Goodwin, DDS, PhD, and Kyle Jones, DDS, PhD
771 Minimally Invasive Veneer Restorations: Effect of Restorative Material on Traumatic Impact Strength
This article discusses how modern restorative materials and adhesive techniques are capable of restoring
traumatized teeth to the impact strength of natural intact teeth.
Michelle Yang, BS; Erik Balinghassay, BS; Johnny Huynh, BS; Xuehui Liu, DDS; Chunling Ge, DDS PhD;
and Shane Newport White, BDentSc, MS, MA, PhD
777 Titanium-Oxide Nanoparticles and Nanofibers Used Alone or With UV Light Activation
This study evaluated the change in oxidation potential of synthesized TiO2 nanofibers (NFs) compared
to commercial TiO2 nanoparticles (NPs).
Christina Chi, BA, DDS; Brittney N. Springer, BS; Elvin Walemba, BSc, MRes, PhDc; Kevin E. Nick, PhD; Christopher C. Perry, PhD;
and So Ran Kwon, DDS, MS, PhD, MS
783 Clinical and Microbial Changes in Orthodontic Patients Using Clear Aligners Vs. Fixed Appliances
This pilot study investigated the clinical and microbial changes that occur in patients undergoing orthodontic
treatment using fixed appliances and clear aligners.
Joseph Mullen, BS; Melissa Agnello, PhD; Edward Viloria, DDS; Kenneth Chang Chien, BS; Emily Duong, BS; Masuma Rizvi,
BDS; Pega Hajian, BS; Huiying Li, PhD; Baochen Shi, PhD; Kang Ting, DMD, DMedSc; Wenyuan Shi, PhD; Renate Lux, PhD;
and Tingxi Wu, DDS, PhD
793 10-Year Institutional Retrospective Case-Control Study of Medication-Related Osteonecrosis of the Jaw
This study looked at the association between ART and MRONJ for cancer therapy.
Pardis Barati Mahvar, BSc; Amna Imran, DDS, MPhil, BDS; Reyes Enciso, PhD; Andrew Sanapanya, BS; Mohammad Khalifeh, DDS,
MS; Parish P. Sedghizadeh, DDS, MS; and Laurel Henderson, DDS, MS
801 Circadian Behaviors of Oral and Skin Fibroblasts
This study reports fibroblasts derived from mouse palatal mucosa and dorsal skin and suggests that oral wound
healing involving fibroblast repopulation and contraction may follow a diurnal cycle.
John Ngo, BS; Hodaka Sasaki, DDS, PhD; and Ichiro Nishimura, DDS, DMSc, DMD
D ECEMBER 2 0 1 9 755
C D A J O U R N A L , V O L 4 7 , Nº 1 2
CDA Classifieds.
JournaC A L I F O R N I A D E N TA L A S S O C I AT I O N
Volume 47, Number 12
December 2019
Free postings. published by the Editorial Production Manuscript
Priceless results. California
Dental Association
Kerry K. Carney, DDS, CDE
editor-in-chief
Randi Taylor
senior graphic designer
Submissions
www.editorialmanager.
1201 K St., 14th Floor Kerry.Carney@cda.org com/jcaldentassoc
Sacramento, CA 95814 Upcoming Topics
800.232.7645 Ruchi K. Sahota, DDS, CDE January/Importance
cda.org
associate editor of Research in Letters to the Editor
Dental Education www.editorialmanager.
Brian K. Shue, DDS, CDE February/Aesthetics com/jcaldentassoc
CDA Officers associate editor March/CDA’s 150th
R. Del Brunner, DDS Anniversary Subscriptions
president Gayle Mathe, RDH
senior editor
Annual subscriptions are
president@cda.org Advertising available to association
Alice Goodwin, DDS, PhD Sue Gardner members at a rate of $36.
Richard J. Nagy, DDS
Kyle Jones, DDS, PhD advertising sales To manage your printed
president-elect
guest editors Sue.Gardner@cda.org Journal subscription online,
presidentelect@cda.org
916.554.4952 log in to your cda.org
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Kristi Parker Johnson Andrea LaMattina, CDE
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treasurer@cda.org
CDA classifieds work harder to Blake Ellington
Debra S. Finney, MS, DDS, tech trends editor
bring you results. Selling a practice
speaker of the house
or a piece of equipment? Now you speaker@cda.org Jack F. Conley, DDS
editor emeritus
can include photos to help buyers Natasha A. Lee, DDS
immediate past president Robert E. Horseman, DDS
see the potential. pastpresident@cda.org humorist emeritus
And if you’re hiring, candidates Connect to the CDA community by
Management
anywhere can apply right from Peter A. DuBois following and sharing on social channels
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it’s free to all CDA members.
Kristine Allington
Journal of the California Dental Association (issn 1043–2256) is published monthly by the
chief marketing officer
All of these features are designed to California Dental Association, 1201 K St., 14th Floor, Sacramento, CA 95814, 916.554.5950.
Periodicals postage paid at Sacramento, Calif. Postmaster: Send address changes to Journal
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faster than ever. Check it out for director The California Dental Association holds the copyright for all articles and artwork published
herein. The Journal of the California Dental Association is published under the supervision of
yourself at cda.org/classifieds. Cris Weber CDA’s editorial staff. Neither the editorial staff, the editor, nor the association are responsible for
creative and ux director any expression of opinion or statement of fact, all of which are published solely on the authority
of the author whose name is indicated. The association reserves the right to illustrate, reduce,
revise or reject any manuscript submitted. Articles are considered for publication on condition
that they are contributed solely to the Journal of the California Dental Association. The
association does not assume liability for the content of advertisements, nor do advertisements
constitute endorsement or approval of advertised products or services.
Copyright 2019 by the California Dental Association. All rights reserved.
756 D E C E M B E R 2 01 9
Editor C D A J O U R N A L , V O L 4 7 , Nº 1 2
Earworms and Merciful Acts
Kerry K. Carney, DDS, CDE
E
veryone has had it happen.
You hear a tune and cannot
get it out of your mind. When things break down so completely
This phenomenon has been
described as a cognitive itch
that you are living on the street, how does
or an earworm. Once ensconced dental health still come to the fore?
in your thoughts, it is very difficult
to drive out. It can wake you up at
night. It can weave its way into every
thought you have. The song can be in day. She was like a time-lapse video Singing the theme from “Bonanza”
and of itself annoying, like a certain where she is crystal clear and the or the refrain from “War” did not
commercial about donating your cars rest of the population is a blur. eliminate the image from the
to children, or, as in my case, the song People walk past her on their way recurring loop stuck in my head.
can be simply cognitively sticky (like to a temporally structured day in a However, I think I have discovered
almost any song by Phil Collins). life with a reliable social structure. a possible antidote: CDA Cares. I
Online, there are several suggestions But she seemed disconnected, started thinking about CDA Cares.
for how to get rid of these earworms. like a planet without an orbit. San Francisco has just over 8,000
My personal remedy involves either When things break down so homeless individuals. California
non-lexical vocables to the theme completely that you are living on the as a whole has just under 130,000
from “Bonanza” or the insistent refrain street, how does dental health still homeless. That represents about a
from Edwin Starr’s 1969 hit “War.” come to the fore? In a situation with no quarter of the national homeless
The other day, I experienced a social backstop, how does the morning population.1 This population
visual analog of this auditory tic. I ritual of toothbrushing still endure? makes up only a portion of the
was on my way to a meeting of dental When we are presented with a people that CDA Cares helps.
editors in San Francisco. I was scanning picture and no information, we have In 2012, the CDA Foundation
the familiar urban scene through the a tendency to fill in the backstory held its first free dental clinic, CDA
car window when I marked a street based on our own experience or fears. Cares, in Modesto, Calif. This original
vignette. A youngish woman with no I kept thinking: What kind of little experiment was a collaboration with
visible means of support and a large girl was she? Who showed her how the national organization Missions
backpack and a bedroll was leaning to brush her teeth? Who instilled the of Mercy. The CDA Foundation has
against a storefront wall. As I watched, importance of oral hygiene? Was it a now held 16 CDA Cares events. The
she reached into her backpack, pulled hygienist, a dentist, a parent? Or was most recent was held in September
out a toothbrush and toothpaste and it just the continuing echo of Ipana’s in San Bernardino. CDA Cares was
proceeded to brush her teeth and Bucky Beaver ad campaign of the located twice in Modesto, Sacramento
spit over the curb into the street. 1950s that directed the American and Solano County. It has also been
She was as discrete as possible under population to “brush regularly and held in San Jose, San Diego, Pomona,
the circumstances. It made me wonder see your dentist every six months.” Fresno, Ventura, Stockton, San
about her backstory. How did she get Or maybe her oral hygiene ritual Mateo, Bakersfield and Anaheim.
there? What vagaries of nature, nurture was an attempt to normalize her These events are amazing. They
and fortune had led to this point? Since situation as much as possible. Maybe it are like a military operation. The
that moment, that scene has returned helped bring a little order to a chaotic planning begins months in advance.
again and again to my thoughts. situation. Whatever the reason for Local connections are made to
There is no way to discern how her present circumstances, her image outreach organizations that get
that woman is living from day to stayed with me like an earworm. the word to folks who need help.
D ECEMBER 2 0 1 9 757
DEC. 2019 EDITOR
C D A J O U R N A L , V O L 4 7 , Nº 1 2
Before the first patient is seen, the denture patient radiant with surprise The Journal welcomes letters
location is a beehive of activity. Large and pleasure admiring his new smile We reserve the right to edit all
exhibition halls are converted into in the mirror. The patient had not communications. Letters should discuss an
a maze of specialized operations. had teeth for years and that day he item published in the Journal within the last
After a day of erecting privacy got his smile back. He beamed and two months or matters of general interest to our
barriers, laying electrical cables, the legislator got tears in his eyes. readership. Letters must be no more than 500
connecting pipes, setting up chairs It was at that moment that I words and cite no more than five references. No
and organizing the sterilization reflected on how great it is to be illustrations will be accepted. Letters should be
and supplies area, there is palpable a dentist and to be able to give submitted at editorialmanager.com/jcaldentassoc.
excitement and expectation. The someone the gift of their smile. It By sending the letter, the author certifies that
first patients show up the night was a very touching moment that neither the letter nor one with substantially
before so they can be triaged and reminds me of the importance similar content under the writer’s authorship
ready to be seen first thing in the of every single merciful act. has been published or is being considered
morning. It is very moving to see CDA Cares has transformed the for publication elsewhere, and the author
people standing in line long before lives of more than 30,000 people. acknowledges and agrees that the letter and
daybreak so they can be ready to receive Through CDA Cares, California all rights with regard to the letter become the
care as soon as the event opens. dentists have provided oral health property of CDA.
Once the gate opens, the services valued at more than
operation runs smoothly, moving $25 million to individuals who would
patients through intake, medical otherwise go without. With tremendous
history and medical evaluation on attention from the media, policymakers
to triage, radiographs and treatment. and the public, organized dentistry
After the procedures are completed, has increased leveraging power for
the patient is guided to the pharmacy policymaking issues like adding adult
area, if necessary, and then on to an Denti-Cal back into the state’s budget
exit interview. Patients are provided and bringing to light the importance
with contacts to seek ongoing dental of oral health for Californians.
care, and often, community partners Millions of Californians still
are on-site to provide information experience barriers to care. With every
on additional local resources CDA member’s support, the CDA
Many times I have seen patients Foundation continues to build on this
in their exit interview ask how they momentum and create lasting change
can volunteer to help with the next for our state’s most vulnerable citizens.
event. Heartwarming though that If you have never been involved
is, my favorite memory is of a crusty with a CDA Cares event, you are
legislator whom I was guiding on a missing out. As dentists, we have the
tour of the event. He was amazed at immediate gratification of helping
the donated service he witnessed. relieve pain and restore smiles
He was astounded that not only had every day. But the gratification
dentists come from all over California that one feels at the end of a
to donate their time and expertise, CDA Cares event is that feeling
but in many cases had closed their magnified a thousandfold. n
offices and brought their staff with
them to the event. He was very reference
1. Fagan K. SF homeless population swells by 17% in latest
appreciative, but the emotional tally. www.sfchronicle.com/bayarea/article/SF-homeless-
moment came when he watched a population-swells-by-17-in-latest-13851897.php.
758 D E C E M B E R 2 01 9
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allowing us to focus on taking the best care of our patients.”
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Dean L. Duncan, D.D.S. (left); Eric M. Scharf, D.D.S. (right)
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MEMbER FDIC aND Equal HouSINg lENDER
Letter C D A J O U R N A L , V O L 4 7 , Nº 1 2
Medication Safety and Dental Sedation Assistants
I applaud the CDA and Dr. medication identification, preparation
Journa
July 2019
Rothman for the two journal editions and administration to essentially a Patient Safety
Checklists
dedicated to safety in dentistry. As layperson with no medical or nursing
Legal Perspectives
Emergency Medications
C A L I F O R N I A D E N TA L A S S O C I AT I O N
an officer of the American Society background. This is a duty that
of Dentist Anesthesiologists and should only be done by individuals
the California Society of Dentist with an advanced professional
Anesthesiologists, we have long been degree and health care license such
dedicated to advocating for patient as a nurse, pharmacist or doctor.
Safety in
safety in the realm of anesthesia Unfortunately, last year the DENTISTRY
and sedation within dentistry. California legislature passed and Perspectives and Directions
David L. Rothman, DDS
Drs. Stevens and Sarasin’s article the governor signed SB 501. This
titled “Medication Safety: Reducing law reinforced, continues and
Errors and Adverse Drug Events in further codified the legality of this
Dentistry” (September 2019) addresses dangerous practice. This should
medication errors in dentistry. be an affront to anybody who is
Medical errors and, more specifically, invested in patient safety and
medication errors are certainly seeks to reduce medical errors.
problematic. These errors can lead I wholeheartedly encourage any The Editor-in-Chief and Guest
to patient harm and even death. The dental assistant, or for that matter Editor Respond
exact numbers may be debatable, but anyone in dentistry, who takes on Thank you for your letter Dr. Naftalin;
every doctor should consider adopting the task of additional training and we are pleased that you found Drs.
every policy meant to prevent these education. The more that our assistants Stevens and Sarasin’s article informative.
errors from happening. Even one know and understand about the Your letter expressed concerns regarding
death or injury from a preventable procedures we are doing, the better dental sedation assistants (DSAs), which
medication error is one error too many. we are as doctors. But entrusting this provides an opportunity to describe for
However, Drs. Stevens and Sarasin’s important responsibility of sedation and our readers the qualifications of this
article has a glaring omission of a anesthesia mediation administration California dental team member.
systemic potential for medication to minimally trained dental assistants The DSA, enacted in 2009 by the
errors permitted by law in California. cannot replace the rigorous and California Legislature, must complete a
Specifically in California, a “dental accredited education that all licensed Dental Board of California approved course
sedation assistant” can draw up, label doctors and nurses have undergone. of instruction detailed in California Code
and even administer irreversible It is high time that California dentists of Regulations, Section 1070.8, and must
sedative medications into an existing take patient safety seriously. This can pass a permitting examination to practice.
intravenous line in a patient. To start by abolishing a system in place in A DSA’s education and training requires
become a dental sedation assistant, California that allows unqualified and sedation-specific instruction of not less
there is no need for any higher unlicensed personnel to be responsible than 110 hours, and at a minimum must
educational degree. This is on-the-job for the preparation, labeling and include 38 hours of clinical instruction
training in the office of approved oral administration of potentially dangerous and 20 supervised sedation cases.
surgeons. According to the Dental sedative medications. This would be a The DSA’s primary role is to monitor
Board of California’s website, there start that we take patient safety seriously. the sedated patient and be a second pair
are only 13 approved offices to obtain of eyes, ears and hands for the dentist
this training. Ten of these offices do l e n n y n a f ta l i n , d d s providing sedation services. The DSA’s
not offer the course to other dental Vice President, American Society of duties, which are described in detail
assistants outside of their practices. Dentist Anesthesiologists in the Dental Practice Act, Section
No other health care model would President, California Society of Dentist 1750.5, require direct supervision as
delegate such critical duties such as Anesthesiologists described further here (italics added):
D ECEMBER 2 0 1 9 761
DEC. 2019 LETTER
C D A J O U R N A L , V O L 4 7 , Nº 1 2
■■ (b) Monitor patients undergoing ampule and vial preparation, personnel to be responsible for the
conscious sedation or general and withdrawing drugs of preparation, labeling and administration
anesthesia utilizing data from correct amount as verified of potentially dangerous sedative
noninvasive instrumentation … by the supervising dentist. medications” is unfounded and not
(b) Monitor patients undergoing ■ ■ (d) Add drugs, medications and consistent with the requirements of the law.
conscious sedation or general fluids to intravenous lines using a We appreciate your continuing
anesthesia utilizing data from syringe, provided that a supervising leadership and interest in patient safety
noninvasive instrumentation . . licensed dentist is present at the and the series of articles on safety.
. evaluation of the condition of a patient’s chairside . . .The exception Thank you again for taking time to
sedated patient shall remain the to this duty is the initial dose of a drug participate in the forum of ideas that
responsibility of the dentist or other or medication shall be administered the Journal of the California Dental
licensed health care professional by the supervising licensed dentist. Association promotes. Discussions such
authorized to administer [sedation], Further, current law requires a DSA as this can only bring more light on the
who shall be at the patient’s chairside to be dedicated to monitoring and subject and promote positive change.
while [sedation] is being administered. sedation assisting functions and cannot kerry k. c arne y, dds, c de
■■ (c) Drug identification and also be assisting the dentist for the dental Editor-in-Chief
draw, limited to identification treatment. Your assertion that California d av i d l . r o t h m a n , d d s
of appropriate medications, law allows
7.375 in. “unqualified and unlicensed Guest Editor
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762 D E C E M B E R 2 01 9Reviewers C D A J O U R N A L , V O L 4 7 , Nº 1 2
Thank You to the 2019 Reviewers
The Journal of the California Dental Association is grateful for the many professionals who formally
reviewed manuscripts in 2019 and offered their recommendations. We extend our thanks to those
who are instrumental in helping us produce this award-winning scientific publication.
Ahmad Abdelkarim, DDS, MS, PhD, Ronald L. Ettinger, BDS, MDS, DDSc Stuart E. Lieblich, DMD Charles Rosson, DMD
DMD, EdD Leticia Ferreira, DDS, MS Brent Lin, DMD David Lawrence Rothman, DDS
Marco M. Allard, PhD Jared Ira Fine, DDS, MPH Jeffrey W. Lineberry, DDS Gary Sabbadini, DDS
Pamela Alston, DDS, MA Barry Freydberg, DDS Sanjay M Mallya, BDS, MDS, PhD Roberto Savignano, MS, PhD
Craig W. Amundson, DDS Yuwei Fan, PhD David John Manton, BDSc, MDSc, PhD Krunal Sherathiya, DDS
Elizabeth Andrews, DDS, MS Fariborz A. Farnad, DMD Leonardo Marchini, DDS, MSD, PhD Werner Shintaku, DDS, MS, MS
Homayon Asadi, DDS James Fedusenko, DDS, RN Michael Marshall, DDS, HDS Charles Shuler, BSc, DMD, PhD
Kathryn Atchison, DDS, MPH Alan L. Felsenfeld, DDS Michael Mashni, DDS Harel Simon, DMD
David M. Avenetti, DDS, MPH, MSD Leticia Ferreira, DDS, MS Melanie E. Mayberry, DDS, MS Krikor Simonian, DDS, DABP
Leif K. Bakland, DDS Jared Ira Fine, DDS, MPH Keith A. Mays, DDS, MS, PhD Harold C. Slavkin, DDS
Jeffrey Banas, PhD Tracy L. Finlayson, PhD Maureen McAndrew, DDS, MSEd Rebecca L. Slayton, DDS, PhD
Nicole Barkhordar, DDS, MEd Steven Friedrichsen, DDS Carol J. McCutcheon, DDS Colby Smith, DDS
Dane Barlow, BBA Barry Freydberg, DDS Daniel W. McNeil, PhD Richard D. Smith, DDS
Jane R. Barrow, MS Sangeeta Gajendra, DDS, MPH, MS Eric P. Mediavilla, DDS Eric C. Sung, DDS
Forrest Batz, PharmD Desmond Gallagher, DDS, MA Michael Meharry, DDS Roy L. Stevens, DDS
Ken Berley, DDS, JD Steven Ganzberg, DMD, MS Mike Meru, DDS Montry Suprono, DDS, MSD
John L. Blake, DDS Clarisa Amarillas Gastelum, DDS, MS Diana Messadi, DDS, MMSc, DMSc Marlene Talley, DDS
Alan O. Blanton, DDS, MS Lawrence Gettleman, DMD, MSD Michael Monopoli, DMD, MPH, MS Parihan Tamkin, DDS
George Bogen, DDS Jay Golinveaux, DDS, MS Alireza Moshaverinia, DDS, MS, PhD Thomas Tanbonliong Jr., DDS
Robert L. Boyd, DDS Anupama Grandhi, DDS Sherry A. Mostofi, Esq. Scott L. Tomar, DMD, DrPH
Ronni Elise Brown, DDS, MPH Mina Habibian, DMD, MS, PhD Richard P. Mungo, DDS, MSD, MEd Janice A. Townsend, DDS, MS
Michael E. Cadra, DMD, MD Magnus Hakeberg, DDS, PhD Carol Anne Murdoch-Kinch, DDS, PhD Philip A. Trask, DDS, MS
Benjamin Chaffee, DDS, MPH, PhD Marc Hayashi, DMD Theodore A. Murray Jr., DDS Richard D. Trushkowsky, DDS
David W. Chambers, EdM, MBA, PhD Lisa Heaton, PhD Richard J. Nagy, DDS Cynthia S. Valle-Oseguera, PharmD
Hubert Chan, DDS Reza Heshmati, DDS, MPH, MS Ichiro Nishimura, DDS, DMD Suvendra Vijayan, BDS, MPH, MS
David Clark, DDS Edmund Hewlett, DDS Nooshin Noghreian, DDS Marisa K. Watanabe, DDS, MS
Paulo G. Coelho, DDS, PhD Helia Hooshangi, DDS Adamo E. Notarantonio, DDS Darien Weatherspoon, DDS, MPH
Susan E. Coldwell, PhD Michelle Hurlbutt, RDH, MSDH, DHSc Brian Novy, DDS Mea A. Weinberg, MS, DDS
Scott Conley, DDS Nicola P.T. Innes, PhD, BDS, BSc, BMSc Dennis P. Nutter, DDS Jane A. Weintraub, DDS, MPH
Leopoldo P. Correa, BDS, MS Robert Isman, DDS, MPH Gregory Olson, DDS, MS John F. Weston, DDS
Santos Cortez, DDS Lisa Itaya, DDS Daniel L. Orr, DDS, MS, PhD, JD, MD Kyumin Whang, BS, MS, PhD
Jean L. Creasey, DDS Shankar Iyer, DDS, MDS Joan Otomo-Corgel, DDS, MPH Kimberly G. Whippy, DMD
David R. Cummings, DDS Poonam Jain, BDS, MS, MPH Udochukwu Oyoyo, MPH Tiril Willumsen, Dr Odont
Eve Cuny, MS Daniel Jenkins, DDS Mariela Padilla, DDS, MEd Lukaz Witek, MSci, PhD
Arthur Curley, JD Ginny Jorgensen, CDA, EFDA Robert J. Palmer Jr., PhD Cun-Yu Wong, DDS, PhD
Michael John Danford, DDS John R. Kalmar, DMD, PhD David W. Paquette, DMD, MPH, Tim Wright, DDS, MS
Karen K. Daw, MBA, CECM Mathew Thomas Kattadiyil, BDS, DMSc Benjamin M. Wu, DDS, PhD
Martin Denbar, DDS MDS, MS Seena Patel, DMD, MPH Juan Fernando Yepes, DDS, MD,
Raymond Dionne, DDS, PhD Cristin E. Kearns, DDS, MBA Tejas Patel, DMD, BDS MPH, MS, DrPH
Sophie Domejean, DDS, PhD Chun K. Kim, DDS Steven Perlman, DDS, MScD, DHL Simon Young, DDS, MD, PhD
Mark Donaldson, PharmD Perry Klokkevold, DDS, MS Ove Peters, DMD, MS, PhD Ling Zhan, DDS, PhD
Evelyn Donate-Bartfield, PhD Gregory Kolber, DDS Peter J. Polverini, BS, DDS, DMSc Anthony J. Ziebert, DDS, MS
Lori L. Doran-Garcia, DDS Jayanth Kumar, DDS, MPH Doreen Pon, PharmD
Rena D’Souza, DDS, MS, PhD Satish Kumar, DDS, MDSc, MS Iain Pretty, BDS, MSc, PhD
Piedad Suárez Durall, DDS Kevin Kwiecien, DMD, MS Fred Quarnstrom, DDS Every effort was made to ensure the
Chad Edwards, DDS Clarice S. Law, DMD, MS Christine Quinn, DDS accuracy of the list of contributors. If
Sridhar Eswaran, BDS, MS, MSD Irving Lebovics, DDS Jack Ringer, DDS you discover an error or omission,
Rhonda Everett, DDS, MPH Cindy Lebovics, RDH, DDS, EdD Alvin Rosenblum, DDS please accept our apologies.
D ECEMBER 2 0 1 9 763Be a part of what’s next
as CDA celebrates 150 years.
Explore new benefits and renew
your membership for 2020 at
cda.org/renew.
BE BOLD.
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WE ARE
LIMITLESSImpressions C D A J O U R N A L , V O L 4 7 , Nº 1 2
Anesthetic Approaches for
Special Needs Patients
A recent study found that safe, successful dental
treatments in special needs patients depend on choosing
the right anesthetic methods and equipment and having
a skilled staff. The study was published in the Journal
of Dental Anesthesia and Pain Medicine in August.
Researchers found that the use of local anesthesia is
sufficient for completing simple dental treatments, with 90%
of patients in the study tolerating it. About 7% of patients
needed additional analgesia and about 3% of patients were given
narcotic analgesics in treatments that caused severe pain.
The study aimed to provide content about the different
anesthetic approaches used in patients with special needs
and included the medical records of 710 patients with
special needs who were treated with general anesthesia
or sedation. The patients ranged in age from 1 to 68.
For comparisons, the patients were evaluated according
to the following groups: Down syndrome, other syndromes,
psychiatric disorders, physical disabilities and complicated
medical stories. Complicated medical stories included those
patients who had conditions that affected their mental and
motor abilities, such as cerebral palsy and spina bifida.
About 73% of patients were given general anesthesia
and approximately 22% were sedated, according to the study.
The mean duration of anesthesia was about 43 minutes.
Simple dental treatments were performed in patients
in all groups, but the most common complications were
found in those from the other-syndromes group.
The patients with other syndromes underwent
maxillofacial procedures to correct facial deformities
caused by self-injurious behaviors. Clinicians shortened
anesthesia periods as much as possible for those in this
group due to their life-threatening conditions.
Despite taking these steps, the author found that clinicians
could not provide optimal treatments for these patients and
only performed symptomatic and not restorative treatments.
Due to the difficult vascular access in other-syndrome patients,
sevoflurane inhalation was used to extract teeth. Though very
few patients were administered general anesthesia, this group
experienced the highest complication rates, according to the author.
Patients with Down syndrome had specific diseases and
conditions, such as respiratory system-related anomalies
and severely low heart rates, that affected the types of
anesthetic approaches used. Sedation was chosen for patients
with Down syndrome due to intubation difficulties.
Although this is a complex subject, the common
point was that all these patients required special care
during dental procedures, according to the study.
Learn more about this study in the Journal of Dental Anesthesia
and Pain Medicine (2019); doi.org/10.17245/jdapm.2019.19.4.191. n
D ECEMBER 2 0 1 9 765DEC. 2019 IMPRESSIONS
C D A J O U R N A L , V O L 4 7 , Nº 1 2
Periodontitis Associated With Hypertension Risk
Ultrasound Tops CBCT in People with periodontitis have a greater likelihood of hypertension,
Peri-implant Bone Imaging according to a study conducted by researchers from the UCL Eastman
Dental Institute in the U.K. and published in Cardiovascular Research.
Cone beam CT (CBCT) is considered This study compiled the best available evidence to examine the odds
the gold standard for imaging peri-implant of high blood pressure in patients with moderate and severe gum disease.
bone, but researchers from RWTH A total of 81 studies from 26 countries were included in the meta-analysis.
Aachen University Medical School in Moderate-to-severe periodontitis was associated with a 22% raised
Aachen, Germany, wondered if another risk for hypertension, while severe periodontitis was linked with 49%
modality without the radiation dose higher odds of hypertension, according to the study.
might be more accurate. They tested “We observed a positive linear relationship, with the hazard of high
CBCT against high-frequency ultrasound blood pressure rising as gum disease became more severe,” said lead
and reported a surprising conclusion. author Eva Munoz Aguilera, MClinDent.
Ultrasound had a lower mean Average arterial blood pressure was higher in patients with
measurement error compared with periodontitis compared to those without. This amounted to 4.5 mmHg
CBCT, while both modalities had higher systolic and 2 mmHg higher diastolic blood pressures.
the same maximum error, leading the “The differences are not negligible,” said Dr. Munoz Aguilera. “An
researchers to conclude that high- average 5 mmHg blood pressure rise would be linked to a 25%
frequency ultrasound may be useful increased risk of death from heart attack or stroke.”
clinically, according to the study published Hypertension, which affects 30% to 45% of adults and is the leading global
in the Journal of Clinical Medicine. cause of premature death, is the main preventable cause of cardiovascular disease.
“Within the simulated limited
Periodontitis affects more than 50% of the world’s population and has been
conditions of this study, high-frequency
associated with increased risk of heart attack and stroke.
ultrasound, with optical scanning used
While the study investigated gum disease as a potential risk factor for
as a reference, presented higher accuracy
hypertension, the reverse could also be true. Further research is needed to examine
in comparison to CBCT, and seems to
whether patients with high blood pressure have a raised likelihood of gum disease,
be a promising tool for measuring peri-
but in the meantime, it would be prudent for health care
implant bone,” wrote the authors, led
professionals to provide oral health advice to those with
by Juliana Marotti, DDS, MSc, PhD.
hypertension, according to the authors.
CBCT is the gold standard for imaging
peri-implant bone because it can provide Learn more about this study in Cardiovascular
cross-sectional images. However, any Research (2019); doi.org/10.1093/cvr/cvz201.
artifacts seen on images may jeopardize
the viewing of the bone-implant interface
and make it challenging to assess peri-
implant bone. Researchers also noted research has shown that ultrasound can Sirona) and an extraoral optical scanner
that CBCT is not recommended for reliably evaluate soft tissues, bone surfaces (D250, 3Shape) for comparison.
evaluating asymptomatic implants and dental implants without ionizing “Ultrasound showed a higher
in periodic exams to avoid patient radiation, according to the authors. accuracy in comparison with CBCT,
exposure to high levels of radiation. Researchers placed four dental while its measurement error was closer
Because of these limitations, researchers implants in eight porcine bone samples. to the optical scan values to a small
wanted to see if high-frequency ultrasound Each implant was scanned by a high- degree,” the authors concluded.
could measure bone thickness in the frequency ultrasound scanner (a prototype Learn more about this study in the
buccolingual region of dental implants developed at RWTH Aachen University), Journal of Clinical Medicine (2019);
with the same accuracy as CBCT. Previous a CBCT unit (Sirona Galileos, Dentsply doi.org/10.3390/jcm8101539.
766 D E C E M B E R 2 01 9C D A J O U R N A L , V O L 4 7 , Nº 1 2
Oral Splint Can Reduce Tourette Syndrome Tics
Researchers in Japan have developed the everyday lives of individuals with
a removable dental appliance that Tourette syndrome, a neurological disorder
can reduce vocal and motor tics in characterized by vocal and motor tics.
children and adults who have Tourette While there is no cure for Tourette
syndrome, according to a study published syndrome, several options are available
in Movement Disorders. The ability to to treat severe tics. These options include
ameliorate tics could positively impact behavioral, pharmacological and more
A custom-made oral splint. The splint applied
to the bilateral molar teeth can increase the
occlusal vertical dimension. (Credit: Murakami
J, et al. used under CC BY-NC 4.0)
Oral Health’s Role in Overall Health of Elderly
Oral health is a critical component to overall health for all ages, but vigilance intrusive surgical interventions. However,
is especially critical for the elderly, according to a review article recently published the efficacy of these treatments can vary,
in the Journal of the American Geriatrics Society. Without good oral hygiene, the and patients still frequently suffer from
use of fluoride and regular dental care, older adults are more prone to damage to physical, mental and social disabilities.
the oral cavity and the extension of infection into surrounding tissues. As an alternative treatment option,
In the article, researchers from the UConn School of Medicine outline the researchers at Osaka University developed a
potential complications that can arise from poor oral hygiene in older adults and custom-made oral splint. These are typically
emphasize the role of all health care professionals in working to promote good used for unconscious teeth clenching
oral hygiene in this population. and grinding and for temporomandibular
Data from the National Center for Health Statistics indicate that the disorders such as misalignment of the
prevalence of cavities is more than twice as high in older adults than younger teeth or jaw. The oral splint is applied
adults. And as many as 64% of older adults in the U.S. have periodontitis, which to the molars to increase the occlusal
is associated with a variety of medical conditions including cardiovascular vertical dimension and to alter the
disease and diabetes. alignment of the nose, lips and chin.
Researchers noted several populations of older adults who are at increased Biting down on the device immediately
risk for oral health problems, including patients with diabetes, patients with improved both motor and vocal tics in
dementia and those in long-term care settings. 10 of the 14 children and six of the eight
adults who participated in the study.
Patients with replacement heart valves and prosthetic joints should be
“What’s more, these effects were
particularly careful regarding their oral hygiene, according to the authors.
long lasting. Long-term improvements
Manipulation of teeth and their support structures can result in bacteria present in
in motor tics after more than 100 days
the oral cavity being released into the bloodstream, which may lead to infections
were especially evident in patients
in parts of the body far removed from the oral cavity.
who were younger when their tics first
Patrick Coll, MD, professor of family medicine and medicine at the UConn started,” said Jumpei Murakami, DDS,
School of Medicine and lead author, said health care professionals should PhD, joint first author of the study.
consider an oral examination during an annual While it isn’t yet clear how the oral
wellness visit, especially for those patients who splint exerts these effects, the action
are not receiving regular dental care. of biting down could serve as a sensory
Read more of this review article in the trick. Sensory tricks are voluntary
Journal of the American Geriatrics Society maneuvers that usually involve touching
(2019); doi.org/10.1111/jgs.16154. parts of the face and head and can
alleviate involuntary movements.
Read more of this study in Movement
Disorders (2019); doi.org/10.1002/mds.27819.
D ECEMBER 2 0 1 9 767introduction
C D A J O U R N A L , V O L 4 7 , Nº 1 2
Spotlight on Dental
Student Research
Alice Goodwin, DDS, PhD, and Kyle Jones, DDS, PhD
GUEST EDITORS
A
Alice Goodwin, DDS, Kyle Jones, DDS, PhD, s dental educators, we are during dental school fosters this skill
PhD,is an assistant is an assistant clinical sometimes asked by dental by exposing students to the scientific
professor at the University professor at the University students and seasoned method. Dental student researchers
of California, San Francisco, of California, San Francisco,
School of Dentistry. School of Dentistry
clinicians alike why research learn to be curious, make thoughtful
She is an American and is a diplomate of during dental school is and quantifiable observations and
Board of Orthodontics the American Board of important, particularly for those who develop questions and methods to
certified orthodontist and Oral and Maxillofacial wish to pursue clinical careers outside answer them. These skills have wide-
researcher investigating Pathology. His research of dental academia. While it is clear ranging practical applications in clinical
the molecular biology focuses on how the immune
underlying craniofacial system is altered in head
to most that dental research is critical practice, from treatment planning
anomalies, in particular and neck precancerous for training the next generation of to quality assurance programs, all of
clefting of the secondary lesions and tumors, with the basic and clinical scientists who will which are important in an increasingly
palate and disorders of the goal of improving current move the dental profession forward, competitive business environment.
temporomandibular joint. immunotherapies for these we strongly believe that it also imparts Lifelong learning founded on
Conflict of Interest diseases.
Disclosure: None reported. Conflict of Interest
many important skills that are vital evidence-based dentistry is vital for
Disclosure: None reported. for clinical practice and continued clinicians to provide the safest, most
professional and personal development. effective treatments for their patients.
We believe exposure to research teaches Dental student researchers learn to seek
dental students to think critically, out and critically evaluate information
evaluate scientific literature, critique in an ever-evolving scientific literature.
their own work and collaborate with Whether looking up an optimal assay to
mentors and colleagues, which are all run for an experiment or investigating
essential skills in clinical practice. which dental material is best for a
The ability to think critically particular clinical scenario, the ability
is key to providing individualized to critically evaluate research studies
patient care and improving clinical is important and directly impacts
outcomes. Basic and clinical research decision-making in clinical practice.
D ECEMBER 2 0 1 9 769introduction
C D A J O U R N A L , V O L 4 7 , Nº 1 2
Furthermore, research teaches Science is truly a team pursuit We appreciate that research is not
students to critically evaluate their and often requires expertise from an undertaking for the faint of heart; it
own work and to not give up when multiple people in order to answer is often fraught with challenges, failures
times are difficult. These important challenging scientific questions. and frustrations. Therefore, we would
traits are directly applicable to clinical Similarly, dentists can utilize this like to acknowledge the hard work and
training and practice, especially spirit of collaboration in their own determination of the dental student
when learning to master new clinical practices, whether consulting with a researchers who took on complex
skills. Providers should continually group of specialists on a complicated scientific questions and pursued
strive for improvement through self- case or developing a strong and challenging projects, which resulted
reflection and evaluation of their cohesive office team. For these and in these peer-reviewed manuscripts.
own work and business practices, many other reasons, we feel strongly Additionally, we would like to thank
which can improve the quality and that research opportunities during the mentors of these students, because
efficiency of care provided to patients. dental school provide myriad learning mentorship and guidance is essential
Finally, research teaches experiences to dental students that at every step in one’s training,
students the need to create strong are directly applicable to their futures especially as a burgeoning scientist.
collaborative working relationships. in clinical practice and patient care. In this issue, we are excited to
present scientific articles on a wide
range of dental-related topics from
students and mentors at multiple
dental schools. We believe that the
breadth of topics highlighted in this
issue reflects the immense variety of
topics in the broader field of dental
research. Thank you again to all of the
dental student researchers, mentors
and their collaborators for the hard
work that went into preparing these
articles. We hope our readers enjoy
this issue as much as we have. n
770 D E C E M B E R 2 01 9veneer restorations
C D A J O U R N A L , V O L 4 7 , Nº 1 2
Minimally Invasive Veneer
Restorations: Effect of
Restorative Material on
Traumatic Impact Strength
Michelle Yang, BS; Erik Balinghassay, BS; Johnny Huynh, BS; Xuehui Liu, DDS;
Chunling Ge, DDS, PhD; and Shane Newport White, BDentSc, MS, MA, PhD
a b s t r a c t Traumatic tooth fracture is extremely common in adolescent patients
and restorations need to be long-lasting, aesthetic and resistant to repeated trauma.
Direct resin-composite restorations have generally been used, but minimally invasive
veneers (MIV) now are a conservative and stable alternative. MIVs made of two
different ceramic materials were compared to intact teeth and to resin-composite
controls. Modern restorative materials and adhesive techniques were capable of
restoring traumatized teeth to the impact strength of natural intact teeth.
AUTHORS
T
Michelle Yang, BS,is Xuehui Liu, DDS,is a raumatic dental injury is one behavioral and motor coordination
a dental student at the visiting scholar at the of the world’s most prevalent risk factors to trauma; hence, repeated
University of California, University of California, Los
conditions.1–5 Traumatic tooth trauma is common throughout childhood,
Los Angeles, School of Angeles, School of Dentistry
Dentistry. and an assistant professor fracture is extremely common; adolescence and beyond.5 For this
Conflict of Interest at the Peking University incidence peaks at 4% at 12 reason, teeth and dental restorations
Disclosure: None reported. School of Stomatology, years of age, dropping off slowly over placed to treat primary trauma are
Third Dental Center. the decades (FIGURE 1 ).2,6–8 Because often subjected to additional trauma.5,18
Erik Balinghassay, BS, Conflict of Interest
is a dental student at the
fracture of anterior teeth is frequent Additionally, restorations placed to
Disclosure: None reported.
University of California, in adolescent patients, restorations address carious lesions or aesthetic issues
Los Angeles, School of Chunling Ge, DDS, PhD, need to be particularly long-lasting and may later be subjected to trauma.
Dentistry. is a visiting scholar at the durable. Maxillary incisors are the most In the past, small to moderate defects
Conflict of Interest University of California, Los
affected teeth because of their position on anterior teeth were almost exclusively
Disclosure: None reported. Angeles, School of Dentistry
and an associate professor and proclination. Traumatic fracture treated using resin-composite materials,
Johnny Huynh, BS,is at the Peking University often affects enamel and dentin without but resin composite is subject to wear,
a dental student at the School of Stomatology. disrupting the pulp and necessitating loss of detailed surface texture and
University of California, Conflict of Interest root canal treatment. Prior research on discoloration over time. Large defects
Los Angeles, School of Disclosure: None reported.
Dentistry.
traumatic tooth fracture has generally were generally treated using more stable
Conflict of Interest Shane Newport White, focused on restorative approaches to ceramic materials in the form of full-
Disclosure: None reported. BDentSc, MS, MA, PhD,is crowned and posted teeth.9–15 Little facial veneers or full crowns. Recently,
a professor at the University attention has been given to refracture minimally invasive veneers, partial
of California, Los Angeles,
of restored teeth or to initial fracture of ceramic veneers or ultraconservative
School of Dentistry.
Conflict of Interest previously restored teeth.16–19 Patients veneers have been used to restore
Disclosure: None reported. generally retain the same anatomic, a variety of anterior tooth defects
D ECEMBER 2 0 1 9 771veneer restorations
C D A J O U R N A L , V O L 4 7 , Nº 1 2
(F I G U R E 1 ).20,21 Ceramic materials
are inherently brittle, but no more
brittle than human tooth enamel.22,23
Feldspathic porcelain has long been
used for the fabrication of porcelain FIGURE 1A . FIGURE 1B .
veneers because it is widely available,
simple to use and allows layering and
internal characterization for optimal
aesthetics. More recently, monolithic
glass ceramics have become widely
used; these materials are stronger than
porcelain or tooth enamel, but generally
cannot be internally characterized.
Traumatic injury, such as falling off a
bicycle or skateboard and hitting a tooth
on a sidewalk, entails much higher forces, FIGURE 1C . FIGURE 1D.
stresses and loading rates than chewing. FIGURE S 1. Impact trauma to the permanent incisors. Twelve-year-old boy has fallen on the asphalt playground
So, the investigation of traumatic tooth (A ). Two fractured central incisors with preparations for minimally invasive veneers; tooth No. 8 was used as a
fracture necessitates duplication of model for this study (B ). Feldspathic porcelain veneers (C ). Cemented minimally invasive veneers (D ).
extreme conditions, quite different from
the routine testing of restored teeth
when simulating normal masticatory MANI) (FIGURE 1B tooth No. 8 and A model for incisal trauma illustrated
function. Impact testing of incisor teeth FIGURE 2A ). Sixteen teeth were arbitrarily by Andreasen and Andreasen was
has only rarely been reported.9,12,14,15,24 assigned to each of the four groups: intact followed.25 Teeth were mounted in
We modeled individuals with a control, direct resin-composite control, acrylic resin to simulate bone support at
history of maxillary incisor trauma minimally invasive feldspathic porcelain an angle of 135 degrees ± 5 degrees to
and a proclivity to repeated trauma, veneer and minimally invasive glass-ceramic the horizontal. This angle was chosen
evaluating minimally invasive ceramic veneer. A power analysis based on pilot so as to produce incisal fracture,25–27
restorations through impact testing. We specimens suggested that 11 specimens per whereas, prior impact studies had
hypothesized that teeth restored using group would be sufficient to detect clinically generally used an angle of 90 degrees
minimally invasive ceramic restorations meaningful differences among restoration to produce cervical or root fracture.9,12
would have equal impact strength materials. Restorations were made using An artificial periodontal ligament was
compared to intact unrestored teeth and direct resin-composite (Filtek Z350, 3M not included because it would not
to teeth restored using a conventional ESPE, St. Paul, Minn.), feldspathic porcelain have provided substantial dampening
direct resin-composite material. (VMK Master, VITA, Bad Säckingen, at the high-impact speed used.19,28
Germany) or glass ceramic (IPS e.max, An impact tester, previously described
Methods Ivoclar Vivadent, Schaan, Liechtenstein). by Trabert et al., was used to apply a
Sixty-four intact maxillary incisors An adhesive cement system bonding hammer to the teeth 1 mm ± 0.2 mm
that had been kept wet since extraction agent (Adper Single Bond Plus, 3M ESPE, below the incisal edge (FIGURE 2C ).9,18 The
were given simulated traumatic defects St. Paul, Minn.) was used for the direct pendulum hammer, 800 g in weight, was
(FIGURE 2A ). A high-speed diamond bur restorations, and the indirect restorations lifted to an elevation of 64 degrees on a
(TR-13, MANI, Utsunomiya, Japan) were adhesively cemented (Variolink N with pivot point radius of 0.49 m. Acceleration
with copious water spray was used to make Syntac and Heliobond, Ivoclar Vivadent). due to gravity (9.81 m/sec−2) would
standardized Class IV preparations with a The restored teeth were stored in water for provide the hammer with a certain amount
60-degree facial bevel of 2 mm to 3 mm in one month then artificially aged by thermal of kinetic energy at the bottom of the
length (TR-13, MANI) and a 45-degree cycling from 5 degrees to 55 degrees Celsius swing. By securing the tooth specimen at
lingual bevel of 1 mm in length (TR-13EF, for 1,500 cycles with 30-second dwell times. the bottom, the pendulum would strike
772 D E C E M B E R 2 01 9C D A J O U R N A L , V O L 4 7 , Nº 1 2
100 ANOVA, for differences among groups, p = 0.2
Differences among groups were not discerned
80
Impact strength in kJm–2
60
FIGURE 2A . 40
20
0
Intact Glass- Feldspathic Direct
natural ceramic porcelain resin-
tooth MIV MIV composite
FIGURE 2C .
FIGURE 2B . FIGURE 3 . Impact strength by restoration type,
FIGURE S 2 . Impact testing. Incisor with simulated group means and standard errors is displayed.
traumatic defect (A ). Incisor with restored defect (B ). None of the groups differed from one another, p = 0.2
Pendulum impact testing machine; the blue arrow (MIV = minimally invasive veneer).
indicates the position of the mounted specimen,
incisal edge up; the red arc illustrates the swing of the
pendulum through the incisal edge of a test specimen
(C ). Restored incisor after impact testing where the
fracture line was diagonal, removing some enamel and
some restoration without involving dentin (D ).
FIGURE 2D.
and break the specimen’s incisal aspect. of variance (ANOVA) (α < 0.05). Fractographic analysis indicated
The pendulum would continue to swing The specimens were qualitatively that fractures were generally
onward and upward after the impact to evaluated for fracture patterns, whether subhorizontal to diagonal, removing
an elevation somewhat lower than that the line of fracture involved tooth part or all of the incisal edge
of a free swing. Impact strengths in kJ/m−2 structure, restoration or both. and that enamel was generally
were determined by how much kinetic involved (96% of fractures);
energy the hammer lost during impact Results dentin was less frequently fractured
as assessed by the difference in energy One-way ANOVA did not discern (21%, F I G U R E 2 D , FI G URES 4 ).
between the pendulum’s initial release any differences among the four Occasionally, scallop-shaped defects
angle and its maximum terminal angle groups (p = 0.2, F = 1.6) (F I G U R E 3 ). in enamel or restorative ceramic
divided by the area of the fracture.28 The Teeth restored using minimally were produced indirectly on the
energy absorbed at fracture is a reflection invasive ceramic restorations had palatal aspects of the incisors (4C p ).
of the relative strength of the whole system equal impact resistance compared Experimental variance was
enduring an impact force.14 This approach to intact unrestored teeth and to extremely high (FI G URE 3 ).
was verified in pilot testing to produce teeth restored using a conventional The effect of impact trauma
incisal fracture rather than cervical or direct resin-composite material. was strongly influenced by the
root fracture (FIGURE 2D ). A priori, data Restorations behaved like tooth characteristics of the individual
from specimens with only minor injuries < structure with respect to impact tooth. Data from five specimens
3.0 mm2 were to be censored because the damage. Fractographic analysis showed was censored because the traumatic
traumatic injuries would be too small, just that a majority of the fractures (81%) injuries were too small to be
chips rather than fractures, to be considered involved both tooth structure and considered clinically relevant to
clinically relevant to the aim of this study.9 restoration. Few fractures involved tooth the aim of this study. One specimen
Mean group impact strengths and structure alone (9%) or restoration was removed from the intact
their standard errors were calculated. alone (10%). Fracture lines did not natural tooth group, three from the
All four groups were compared for show any marked preference to tooth glass-ceramic group and one from
impact strength using one-way analysis structure, restoration or their interface. the feldspathic porcelain group.
D ECEMBER 2 0 1 9 773veneer restorations
C D A J O U R N A L , V O L 4 7 , Nº 1 2
Impact testing is used to model
FIGURE 4A . Facial surface (left), palatal surface (right). situations that manifest severe
shock loads, such as those caused by
instantaneous arrest of a falling mass or
the shock meeting of two objects with an
exceptionally rapid build-up of stress.30,31
In contrast to quasistatic testing, the
loading velocity in a pendulum test is
typically several m/sec−1 with a duration
FIGURE 4B . Facial surface (left), palatal surface (right). of m/sec, many orders of magnitude
faster that in routine mechanical
tests.16,27 Some “impact” strength tests
on reattached anterior tooth fragments
used a conventional universal testing
machine at a crosshead rate of 0.5 m/
min–1, but that was still several orders of
magnitude slower than in this current
FIGURE 4C . Facial surface (left), palatal surface (right).
pendulum test or in real-world impact
FIGURES 4 . Restored teeth after impact testing. Glass-ceramic MIV, partly retained facially (A). Feldspathic porcelain trauma.16–18 High velocity is important
MIV, partly retained facially Bf; some palatal enamel lost Bp (B). Feldspathic porcelain MIV largely destroyed Cf, some because the material at the tip of a
facial and much palatal enamel lost Cf and Cp and some dentin lost Cp (C) (MIV = minimally invasive veneer). growing crack is strained extremely rapidly
and may offer lesser or greater resistance
to crack growth and fracture than at
Discussion routine low quasistatic strain rates.
This in vitro study suggests that fragment rebonding on sheep incisors At the high load rates and stress
minimally invasive porcelain or glass- found no difference between teeth with intensities inherent to impact trauma,
ceramic veneers are a clinical option in rebonded coronal fragments and intact all of the bonded restorative materials
repairing fractured or carious incisors. control teeth.16 A quasistatic study found behaved remarkably like tooth structure
Minimally invasive ceramic veneers no difference in fracture resistance of teeth itself; cracks did not have a preference
conserve more precious tooth structure restored with either feldspathic porcelain for tooth, restoration or their interface.
than conventional veneers and or resin-composite veneers.26 The This finding may appear to be somewhat
considerably more than full crowns. Their restorative materials and adhesives used surprising; however, materials such as resin
finish lines are usually above the gingiva, in this study, and in prior studies, were not composite, which exhibit toughness at
leaving the natural emergence profile and weak links.16,19,23 Thus, modern restorative low strain rates, can behave differently at
contour unaffected, promoting gingival materials and adhesive techniques are high strain rates. Conversely, inherently
health and a natural appearance. They capable of restoring traumatized teeth to brittle materials, such as ceramics, may
also provide more dimensional stability, the impact strength of natural intact teeth. become tougher at high strain rates. These
wear resistance and color stability than Generally, quasistatic load-to-failure results may also apply to other clinical
direct resin-composite restorations. tests have been used to assess the strength situations where high strain rates are
The results were consistent with of restored teeth, but such methods encountered, such as accidents that cause
findings of prior studies insofar as they do not simulate the very high load the teeth to smash together or unexpected
intersected. An impact study of incisors rates of impact that lead to traumatic biting on a shard of bone, a grain of sand
restored with partial coverage glass- injury. Impact testing, as used in this or on lip- or tongue-piercing jewelry.
ceramic restorations determined that study, is a clinically relevant model of Impact testing typically produces high
their fracture resistance and severity of both trauma and accidentally biting experimental variance, even more so
crown fracture did not differ from intact on hard substances, but has only very when brittle materials are evaluated.9–11
unrestored teeth.19 An impact study of rarely been used in dental studies.29 The problem of variance can be addressed
774 D E C E M B E R 2 01 9You can also read
