The Most Controversial Subject in Dentistry

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Sci Forschen
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Internaonal Journal of Denstry and Oral Health
ISSN 2378-7090 | Open Access
Int J Dent Oral Health | IJDOH
1
COMMENTARY
The Most Controversial Subject in Denstry
Gene McCoy*
Denst in San Francisco, California, USA
Received: 25 Aug, 2021 | Accepted: 14 Sep, 2021 | Published: 20 Sep, 2021
Volume 7 - Issue 7
*Corresponding author: Gene McCoy, Dentist in San Francisco, California, USA, E-mail: genemccoydds@sbcglobal.net
Citaon: McCoy G (2021) The Most Controversial Subject in Denstry. Int J Dent Oral Health 7(7): dx.doi.org/10.16966/2378-7090.382
Copyright: © 2021 McCoy G. This is an open-access arcle distributed under the terms of the Creave Commons Aribuon License, which permits
unrestricted use, distribuon, and reproducon in any medium, provided the original author and source are credited.
Introduction
Dental occlusion had always been dened as teeth in closure [1],
but at one point, there was a movement within the dental profession
to modify the meaning. e dentists behind the movement, Mohl
explained, felt that the denition: “Did not truly dene the eld
because its’ signicance was much more than the occlusal contact
relationship of the dentition” [2]. ey felt that the word occlusion
should be construed as an understanding of the masticatory system
itself. In due course the movement was successful, and the word
occlusion became synonymous with the masticatory system, but
without rules. ere was no explanation as to what constituted an
ideal occlusion or how to achieve it, so practitioners were unsure of
their goals. e lack of clarity subsequently prompted practitioners to
formulate their own ideas as to how the system should work which
made it impossible to develop intelligent diagnostic criteria and
promulgate treatment.
is commentary/opinion is an account of the factors that have
made this subject the most controversial subject in dentistry, and
suggestions for the restorative dentist to achieve and maintain a
healthy, comfortable, and ecient masticatory system.
Exactly, what is occlusion?
is is the heart of the problem, an understanding of just what
occlusion signies. In medicine, it means to close, obstruct, or prevent
a passage such as blood in an artery or vein [3]. In dentistry however,
it is understood to be the manner in which teeth come together in
closure [4]. Seems simple enough, but over time the dental denition
was modied to include the contact of teeth during those excursive
movements of the mandible essential to mastication [5]. is was
curious since it is not normal to eat our food in excursive movements
and recognizing that teeth rarely touch when mastication does occur.
Still, another interpretation was imminent.
Up to a point, all of the dental dictionaries had dened dental
occlusion as the closure of teeth except one: Jablonski’s Dictionary
of Dentistry [6]. Dentists were becoming comfortable with using
the word occlusion for just about anything related to the masticatory
system which instigated a movement to personalize the denition and
Jablonski gave them that opportunity.
Stanley Jablonski was a prolic writer of medical and dental books
including a Russian-English dictionary. He used an encyclopedic
approach, and to explain areas of particular complexity, he relied
on glossaries and consultants as primary sources of information.
To compile his Dictionary on Dentistry he used 31 consultants, 13
of which were dentists and 18 credentialed authorities in dental
academia [6].
It was from their contribution of information, ideas, and opinions
that Jablonski formulated his denition of occlusion and then the
consultants turned around and quoted him as provenance.
Jablonski’s denition of occlusion
"e relationship between all the components of the masticatory
system in normal function, dysfunction, and parafunction, including
the morphological and functional features of contacting surfaces of
opposing teeth and restorations, occlusal trauma and dysfunction,
neuromuscular physiology, the temporomandibular joint and muscle
function, swallowing and mastication, psychophysiological status,
and the diagnosis, prevention, and treatment of functional disorders
of the masticatory system [6]."
Despite the good intentions, empowering the word occlusion to
describe the masticatory system was just that: a description, not an
analysis. It did not explain how the system should work which created
a distraction rather than an adjunct when evaluating the system
itself and things got complicated. Dentists knew how to analyze the
status of a patient’s masticatory system, but they did not understand
occlusion’s new signicance. What did it mean exactly? What were
the guidelines? How does one assign a meaning to a word that has
two denitions?
ere were no directives. Questions began to emerge along with
multiple concepts that described six dierent mandibular positions,
16 dierent mandibular movements, and thirty dierent occlusal
relationships [4]. e American Dental Association (ADA) needed
clarity and wanted to resolve these issues. In 1952, the ADA sponsored
a Nomenclature Conference to discuss and understand these dierent
points of view [7]. e ocial purpose was to interpret the general
concept of occlusion in its’ broadest signicance. e chairman
was George B. Denton and there were 30 participants. ere was so
much dissention regarding the format that the conference considered

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Citaon: McCoy G (2021) The Most Controversial Subject in Denstry. Int J Dent Oral Health 7(7): dx.doi.org/10.16966/2378-7090.382 2
Internaonal Journal of Denstry and Oral Health
Open Access Journal
only the concepts of occlusion rather than the terms which stood
for the concepts. Both stationary and moving phenomena were
to be considered. Each presented concept was judged to be either;
“harmonious medium occlusion” (functional) or “disharmonious
peripheral occlusion” (parafunctional).
e conference ended without resolving any of the disagreements,
no ocial terminology was adopted, and there were no authoritative
conclusions. It is interesting to note that in this attempt to understand
the essence of occlusion, two categories were recognized; function and
parafunction. e profession continued to debate the controversies.
In 1975 another attempt was made to resolve these controversies
and establish credible guidelines for practitioners to follow regarding
occlusion. e American Association of Dental Schools (AADS)
initiated a workshop in New Orleans to investigate and survey the
trends and goals of occlusal education [8]. Sponsoring institutions
were Louisiana State University, the University of California, San
Francisco, and the University of Southern California. e original
workshop committee, within the Dental Anatomy and Occlusion
Section of the AADS, consisted of: Dr. James Butler, chair, Dr. Rex
Ingram, co-chair, Dr. Marwan Abou-Rass, editor, Dr. Ben Pavone, Dr.
William Solberg, and Dr. Howard Bruggers. Additional consultants
were: Dr. E.E. Jeansonne, Dr. Carl Rieder, Dr. Richard Blagbrough, Dr.
Daniel Isaacson, and Dr James Bruch.
e major goal of the workshop was to prepare a manual to serve
as an educational model for the planning and presentation of an
occlusion curriculum, for undergraduates. e premise was to explain
every aspect of the curriculum so that students could have a clear
objective on what end goals to strive for with good, simple, and logical
points. However, there was no explanation as to what these end goals
were, nor was there an explanation as to what courses were qualied
to achieve them. In addition, there was no formulation of a model of
excellence in regard to the performance of the masticatory system:
how it works eciently and how to make corrections when it does
not. However, two interesting points came to light. Dr. Parker Mahan,
University of Florida, stated that a preferred goal was: “to understand
normal stomatognathic system function, to recognize occlusal
dysfunction, to determine its’ etiology, and how to treat it.” is
observation mirrored the only distinction regarding occlusion in the
1952 Nomenclature Conference, i.e.; harmonious medium occlusion
(functional) vs disharmonious peripheral occlusion (parafunctional).
e other interesting point was presented by one of the speakers, Dr.
Willy G. Krogh-Poulsen, Royal Dental College, Copenhagen; “I think
that the term occlusion should be restricted to dene only contact
relations of the teeth, and that a new term should be created which
will encompass the broader meaning of occlusion.” He suggested that
the term Physiodontics might be considered to serve as an appropriate
term. He went on to say; “A deep understanding of the form-function of
the relationships must be achieved or the student will not understand
the needs of prevention against dysfunction and their sequelae.” e
participants in this workshop were also asked to dene an optimal
design for the relationship between the occlusion curriculum and other
dental disciplines:this request was not fullled. In spite of the fact that
the workshop failed to establish precise guidelines for practitioners
to follow, the ADA Council on Dental Education initiated separate
departments dedicated to occlusion (1980) in 51% of the existing
dental schools [9]. ey were not successful.
In 1983, a new report; Special Guidelines in Occlusion, was
developed by AADS members Dr. James W. Buckman and Dr. Jeery
P. Okeson [10]. Although this report, using the 1975 workshop as a
reference, was entitled Special Guidelines, it failed to dene them.
Curiously, the credibility of this report was undermined by the
following statement: “Although these guidelines were recommended
as course development aids and suggested as ocial AADS policy,
there are not ocial policy statements of the AADS and should not
be construed as recommendations for restrictive requirements.” ere
was no explanation as to the reason why. What is the current situation?
Understanding occlusion, 2013, is an update which begins with,
“Frustration and confusion still reign over this complicated topic”
[11]. In this article, author Jackie Syrop reviews diering philosophies
of occlusion and interviews occlusion experts to gain insight about the
current state of occlusion with the disappointing comment that there
is a “willingness among dentists to concede that no single philosophy
works for all cases.”
Among the experts interviewed was John Kois, DMD, MSD,
director of the Kois Center in Seattle, Washington who stated that;
“Occlusion is the new frontier that is virtually untapped by most of
the profession” [11]. But wait a minute; this is not a new conversation.
Kois’ statement seems to imply that something is missing: that maybe,
we could have been doing something better? A frontier indicates that
there is a limit to our present state of knowledge and there are new
things to be learned, but there is not a single aspect of the masticatory
system that we haven’t analyzed, pondered, debated, and discussed
thoroughly. We just were victims of entrenched thinking. We just need
to rethink what we do know.
Discussion
e morphing of the word occlusion should never have happened.
It was a major distraction to our understanding of the masticatory
system: how it functions properly and what we need to do when it is in
a state of parafunction. In linguistics, it is not unusual for the meaning
of a word to change. It is called a semantic shi and it happens for
various reasons. ere can be a broadening where the word becomes
more inclusive than an earlier meaning, or there can be a narrowing
where the meaning becomes less inclusive, however this was
dierent. A description of the dentition in closure was changed to a
neuromuscular description of the masticatory system as a whole. is
is called a polysemy, where the new interpretation becomes radically
dierent from the original usage. It was a deliberate distortion to
suit an agenda and with sincere respect, it did not make sense. e
masticatory system has three main components: the occlusion, the
muscles of mastication, and the condyle (Figure 1). If we now refer
to the masticatory system as the occlusion system or the occlusion
curriculum (Figure 2), what do we call the contact of teeth in closure?
A biological system is dependent on each component part to
contribute to its’ ecient function as a whole. If we rename the system
to one of its’ component parts, occlusion, how do we dierentiate
between the closure of teeth and the system? Occlusion is not
a curriculum nor is it a system, but rather a component part of an
existing system.
e human body has 12 major body systems. A biological system
is a group of organs that are specically designed to work together to
perform a certain task. e health care practitioner who specializes
in the care of any particular system needs to understand four simple
truths; how the system functions eciently and in good health, the
component parts that enable that system to do so, how to identify the
signs and symptoms of disease or parafunction, and how to correct
or manage the problem. As the cardiologist is responsible for the

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Citaon: McCoy G (2021) The Most Controversial Subject in Denstry. Int J Dent Oral Health 7(7): dx.doi.org/10.16966/2378-7090.382 3
Internaonal Journal of Denstry and Oral Health
Open Access Journal
Figure 1: The Mascatory system is composed of three components.
Figure 2: The Occlusion curriculum does not detail the teeth in closure.
Dening an ideally functioning masticatory system: No matter the
number, arrangement of teeth, or structural dierences between the
mandible and the maxilla, an ideally functioning masticatory system
would be one that is devoid of parafunction. Although the mandible
has the exibility of lateral movement, all functional movements such
as eating, talking, or swallowing are vertical. In the interim of normal
function, the mandible is at rest.
Dening ideal occlusion: What is the most ideal relationship
that teeth should touch each other in closure that ensures an ideally
functioning masticatory system? With the exception of anomalies, our
biological architects designed all our body parts to be perfect. Our
dentition is no dierent. It was designed to cut through food and to
harmoniously interact with the muscles of mastication and the TMJ.
Figure 3 demonstrates nature’s original design [13].
ere are two salient observations: rst, the contact is limited to
the occluding cusp which directs force vectors along the longitudinal
axis to be distributed circumferentially via the roots to the supporting
alveolar bone and second, the incline planes have no contact at all
creating a generousintra-incline space to hold, cut, and diminish food
particles as they begin their journey through the digestive system. is
space also not only reduces collisions during mastication but creates
an anterior-posterior resistance free zone to accommodate changing
mandibular positions during postural changes. In addition, condylar
repositioning is ensured upon swallowing. Although our biological
architects have demonstrated a perfect example of occlusal contact for
harmonious function of the masticatory system, we are not to conclude
that all dentitions should be equilibrated to obtain or maintain this
objective. For many, the loss of the original sharp architecture of the
occlusal surfaces, for whatever reason, may be a natural phenomena,
and does not automatically indicate that an equilibration is required.
e key is comfort. ere are also the architectural dierences in
our skeletons due to genetics. Since not everyone has a class I jaw
relationship and a perfect alignment of teeth, nature’s example
demonstrates that, when considering an equilibration, vertical loading
is preferred and heavy lateral contacts are not.
What is the relationship between occlusion and TMJD?
is is another legacy of the polysemy. e reason this question is so
dicult to answer is that, it’s not the appropriate question. We should
be asking if the TMJ is uncomfortable because the masticatory system
is aected with parafunction and then determine if the way the teeth
coming together is a contributing factor. It would be dicult to do a
study to determine a credible relationship between parafunction and
TMJD, as there are just too many variables such as the type, strength,
and frequency of the parafunction and the biological strength of the
patient. ere are patients who have ground their teeth down to the
gingiva with no discomfort to the TMJ, and those who have developed
TMJD aer the delivery of one uncomfortable restoration that initiated
parafunction.
In my 50 years of restorative dentistry, I have not seen a single TMJD
patient that did not exhibit signs of dental compression syndrome
(DCS), so whatever the etiology of the TMJD, since clenching applies
pressure to the TMJ, it is good common sense to focus on reduction
and management of the same.
Summary
It is the obligation of every restorative dentist to promote oral health
and to prevent disease.
To promote oral health, dentists must maintain good systemic
physiology. Physiology, from the Latin meaning “e study of nature,”
cardiovascular system, so is the dentist for the masticatory system
which is actually a minor system, the gateway to the larger digestive
system whose sole purpose is to convert food in the alimentary canal
into an absorbable form. e masticatory systems’ job is to break down
pieces of food to begin that process. It accomplishes this task with two
opposing, u-shaped rows of overlapping teeth that interact with each
other. When a patient presents for dental restoration, the practitioner
focuses on two objectives: the project at hand and the status of the
masticatory system. If the patient’s system is functioning comfortably
and eciently, the dentist then concentrates on the immediate project
whether it is an alloy restoration, crown, or removable prosthetics.
If however, the system is aected with parafunction, this must be
addressed before the restorative project. e polysemy diverted
practitioner’s attention from the masticatory system to an undenable
goal.
So, if our goal is an ideally functioning masticatory system with
ideal dental occlusion in an ideal world, how would one describe
it? Dawson opines; “We are dealing with a beautifully designed
system that functions in perfect harmony as long as all its structural
components are correctly inter-related” [12]. He’s talking about the
masticatory system, not occlusion. He then asks; “What is the specic
relationship of teeth closure to functional harmony and stability of the
system?” [12].
Now he’s referring to occlusion. So, let’s try to answer Dawson’s
question.

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Citaon: McCoy G (2021) The Most Controversial Subject in Denstry. Int J Dent Oral Health 7(7): dx.doi.org/10.16966/2378-7090.382 4
Internaonal Journal of Denstry and Oral Health
Open Access Journal
is an understanding of various body parts and their functions. Aristotle
was the rst to describe how form and function govern anatomical
studies. e masticatory system is characterized by three main
components (the TMJ, the muscles of mastication, and the design of
the dentition) that interact to form a coherent whole. It should be the
mandate of every restorative dentist to understand and maintain the
harmonious relationship of these three components to promote the
oral health of the system.
e most damaging disease to threaten the integrity of any
masticatory system is parafunction. It should also be the mandate of
every restorative dentist to recognize its’ signs and symptoms and to
council patients as to it’s’ etiology and management.
References
1. Dorland WAN (1898) Dorland’s Pocket Medical Diconary. 1st
Edion, W.B. Saunders Company. Philadelphia.
2. Mohl NDA (1988) Textbook of Occlusion. Quintessence Publishing
Co., Inc. Chicago, Illinois, USA.
3. Taber CW (1960) Taber’s Cyclopedic Medical Diconary. Eighth
Edion, F.A. Davis Company, Philadelphia.
4. Zwemer TJ (1998) Mosby’s Dental Diconary. 1st Edion. Mosby,
Inc., St. Louis, Missouri.
5. Dorland WAN (1959) Dorland’s Medical Diconary. 20th Edion. W.B.
Saunders Company.
6. Jablonski S (1998) Jablonski’s Diconary of Denstry. 2nd Edion.
Krieger Publishing Company, Malabar, Florida.
7. American Dental Associaon (1953).
8. Proceedings of the workshop on Occlusal Educaon (1975).
9. Curricular Guidelines in Occlusion (1983) J Dent Educ 47: 561-565.
10. Syrop J (2013) Understanding Occlusion. Inside Denstry 9: 46-58.
11. Dawson P.E. The Concept of Complete Denstry. A workbook,
copyright 1990 & 1994.
12. McCoy G (2020) The Great Occlusion Fiasco. J Oral Implantrol 46:
139-144.
13. McCoy G (1999) Dental Compression Syndrome, A New Look at an
Old Disease. J Oral Implantrol 5:35-49.
Figure 3: Unworn molars in occlusion.