POINT/COUNTERPOINT

Relationship between occlusion and

temporomandibular disorders: Implications for
the gnathologist
Rudolf Slavicek
Vienna, Austria

T
he succession of hominids about 5 or 6 million homeostasis can be termed “life.” The main purpose
years ago led to continuous development that of an organism is survival.4 Adaptation and habituation
culminated in Homo. The first Homo, also known were first elaborated upon by Jean-Baptiste Lamarck in
by the basic designation of Homo habilis, appeared his second thesis, which discussed the genetic outcome
about 2 million years ago. Some reasons for anthropo- if both sexes are habituated. This definition might also
genesis include posture, speech, brain development, be viewed from the perspective of the second main
and social behavior. The decisive step in evolution theorem of thermodynamics.
occurred when the new phase of linguistic communica- Biologic systems are open systems with a time
tion emerged—ie, descriptive language. In a discussion direction. Here, Prigogine5 described the so-called
between a Nobel prize winner and one of the greatest dissipative structures in general for open systems and
philosophers of the twentieth century, namely Konrad thus also for biologic systems. Processes in biologic sys-
Lorenz and Karl Raimund Popper, the following state- tems are “irreversible.” A major aspect of open systems
ment emerged: “Brain is language, and language is is that all interventions (also therapy) are irreversible.
brain.” Popper took things farther, claiming that brain From the perspective of evidence-based medicine,
is speech, and speech is brain, and that man created when we separate teeth with occlusal aids and then
himself by descriptive speech.1,2 Indeed, the brain de- remove the appliance, a condition of restitutio ad
veloped with drastic speed, and the evolution culmi- integrum can be achieved. From a scientific point of
nated in Homo sapiens. The masticatory organ and view, this is absolutely incorrect.
occlusion are at the center of this link to the develop- Uexk€ull6 initiated a further major modification in
ment of the brain, because linguistic communication biology when he described his new viewpoint about
occurred through this new function. organisms in their environment. If an organism is
confronted with a problem in its environment, the or-
CYBERNETICS AND ORGANISMS ganism recognizes the problem, states its importance,
In 1948, Wiener3 published a provocative scientific reacts, and arrives at a solution to the problem. This
book that first described the concept of networking in reaction is received by the environment as a new reality.
biology. He stated that cybernetic thinking is the link The problem is solved both directly and cognitively!
Humans are a suprasystem with a strong relation-
in the “no man’s land” between the recognized sciences.
ship between the soma and the psyche. Based upon
I describe an organism from the cybernetic point of view
self-consciousness, the human being creates his or
as a highly complex and self-contained system that is
her own individual reality. Because of social structures,
unified by a common (external and internal) flow of in-
education, conventions, inhibited aggression, or the
formation, which compels all internally dependent sub-
unwillingness to be aggressive, problems are usually
systems to undergo reactive changes, and is therefore in
not solved directly but, rather, in a delayed manner,
a state of permanent unstable homeostasis. The perma-
or they remain unresolved. We name this psychic
nent reactive adaptation of an organism to maintain
behavior suppression. Thus, the psyche becomes
a dumping ground for unresolved problems that
remain concealed and cognitively inaccessible.
Professor emeritus, Danube University, Krems, Austria.
Reprint requests to: Rudolf Slavicek, Widerhoferplatz 4/7/51, 1090 Wien,
In summary, the masticatory organ of Homo sapi-
Austria; e-mail, r.slavicek@aers.at. ens is an entirely new evolutionary concept with newly
Am J Orthod Dentofacial Orthop 2011;139:10-6 networked functional spheres—ie, a “new organ.”4 In
0889-5406/$36.00
Copyright Ó 2011 by the American Association of Orthodontists.
our individual ontogenesis, we must rediscover and
doi:10.1016/j.ajodo.2010.11.011 relearn the phylogenetic new functions.
10
12 Point

ONTOGENESIS OF THE MASTICATORY ORGAN the molars determine the movement pattern of the
Before erupting into the oral cavity, the dental crowns mandible.10
are complete morphologic structures, which I define in ge- Compensation of sagittal and transverse discrepancies
netic terms as the 1 structure of the human body that can occurs during this time. The first main factor of compen-
be altered only by destruction. Due to the sequence of on- sation during ontogenesis is dentoalveolar development.
togenesis, I prefer to speak in terms of functional periods The second main factor to compensate skeletal discrep-
rather than use the usual classification of growth periods: ancies is vertical development. The third main factor, es-
the postnatal period, breathing and communication, in- pecially in skeletal Class II malrelationships, is articular
gestion and digestion, preparation of the spine, changing compensation (temporomandibular joint). Malocclusion
nutrition, and mastication and swallowing. in the early mixed dentition must be recognized.

Uprighting Second functional period of the changing dentition

Man’s ontogenetic uprighting caused a massive During the second functional period of the changing
change in the region of the temporal bone. Because of dentition, the premolars erupt, there is narrowing of
the position of the organ of balance and the archways, lateral control, retrusive control in the first premolar oc-
the pyramid had to rotate in the opposite direction dur- curs, and the psychic stress of the beginning of puberty
ing uprighting. Counterrotation concerned not only the starts. The morphology of the premolars—especially
temporal bone but also all bones of the cranium.7,8 that of the first premolar— is the most important prepa-
During the period of the deciduous dentition, the fol- ratory basis for the final dynamics of lateral, retrusive,
lowing typically occur: full development of communica- and protrusive mandibular movements. From the
tive speech, general learning, social adjustment, psychic orthodontic point of view, extractions in this region are
stress management through the masticatory organ, and functionally critical.11
abrasion of the deciduous
dentition. Malfunction and During the maturation of the denti- Functional period of
malocclusion form during this maturation
period. The phase of the ma- tion, the position of the mandible is
During the functional pe-
ture deciduous dentition is determined 3-dimensionally by the
riod of maturation, canine
the longest and most effective occlusion of the teeth. dominance12 is established,
learning period in life. There-
the craniomuscular system
fore, it is a period of extreme
matures into the reference position, second molar
psychic narrowing and loading. At this age, bruxing is
intercuspation develops, and there is increasing psychic
a normal function to unload the psyche.9 The resulting
loading with puberty and increased social integration.
abrasion favors the required protrusive advancement
In conclusion, during the maturation of the denti-
of the mandible.
tion, the position of the mandible is determined 3-di-
mensionally by the occlusion of the teeth.13 It is
First period of the mixed dentition
habituated and controlled proprioceptively, while
With the eruption and coupling of the permanent closing the jaw. The joints are secured vertically by
first molars, the anterior permanent teeth are also the teeth.14
exchanged, intercuspal positions are defined, structural
limitations are established, functional adaptations FUNCTIONS OF THE JAW
(chewing and speech) occur, and the structural adapta-
tion of the temporomandibular joint begins. During Mastication
this period, the temporomandibular joint adapts just In the phase of bolus formation, mastication should
as rapidly. The initial adaptation is functional but is be more of a translatory process. There should be
followed by structural adaptation. This means that minimum rotation. In modern man, optimum dynamic
occlusion dictates adaptation. This ability to adapt mastication is achieved when the rows of teeth are as
functionally as well as structurally persists throughout close to each other as possible without functional inter-
life, but in a less pronounced manner. As early as this ferences.15 Hence, occlusion is undoubtedly the major
point in time, the morphology of the first molars struc- and dominant factor of the system. Occlusion and
turally determines the lateral and retral pattern of the articulation determine the functional patterns of
craniomuscular system. The position and rotation of mandibular movement.

January 2011  Vol 139  Issue 1 American Journal of Orthodontics and Dentofacial Orthopedics
14 Point

The term “disclusion” in our modern occlusal con- compromises or not at all. Such “no solving” of prob-
cepts is a perversion of the central significance of the lems is deposited in the garbage dump of the psyche
masticatory organ: to cut food efficiently. The quality and can be realized at the somatic level through
of intercuspation is important for the physiology of nonpurpose-related emotions.
chewing. Chewing is concluded by the act of swallowing. If chronic pressers and grinders use their mastica-
Intercuspation should be achieved without interference. tory organ as a psychic stress valve, then grinding
The difference between retral contact position and inter- and pressing might be assigned to the normal functions
cuspation in chewing and deglutition is of minor impor- of the masticatory organ.18 For these people, decrying
tance. Chewing and swallowing are patterns adapted to parafunction in the treatment of the masticatory organ
the quality of food and controlled proprioceptively would signify an additional restriction. What is the role
during the sequence of mastication. of occlusion in coping with stress? This discussion must
The necessary information is provided by individual be conducted unemotionally on the basis of scientific
tooth contacts during chewing. The front teeth are findings and conclusions. Grinding and clenching
avoided in mastication. Functional interferences in are expressions of psychic stress assimilation and
occlusion can cause avoidance patterns. Avoidance are controlled by the neuromuscular system and
patterns during mastication and swallowing might be occlusion.19-33
a reason for temporomandibular disorders.

Speech Therapy of occlusion: Goals and concepts

Communication is the main function of the masti- Interventions in the structure of occlusion are
catory organ, and pronunciation is predominantly irreversible. This is based on the widely accepted axioms
related to the anterior teeth. Other teeth and occlusion of the natural sciences. All assertions of reversibility are
might create avoidance patterns causing TMD. scientifically unfounded. Therapeutic interventions
must have a causal reason. The purpose should be
defined, and the aim should concur with the purpose.
Bruxing and clenching (the role of teeth in stress This is applicable to restorative and prosthetic interven-
management) tions in equal measure as it is to orthodontic and max-
The limbic system is the complex system belonging illofacial surgical corrections. After completion of the
to the archaeocerebellum, located between the brain treatment, the result should be biologically stable.34
stem and the neocortex, which is considered to be So-called retentions might be indicated in the phase
responsible for emotion and instinctive behavior. of stabilization, but a general retention of the occlusal
Humanization leads to proportional shifts, which cause outcome is incorrect. Defensive assertions to the effect
aggressive behavior.16 In the evolution of the primate, that therapeutic interventions can have no negative
a strong shift in balance occurs in the region of the consequences are absurd.
amygdaloid nucleus. The centromedial portions “Gnathology” is defined as “the science that treats
(aggression) are markedly reduced compared with the the biology of the masticatory mechanism as a whole:
centrobasolateral (pleasure-oriented) portions. morphology, anatomy, histology, physiology, and
Kail17 stated in her dissertation on our bruxing therapeutics of the jaws or masticatory system and the
patients in the Department of Prosthetic Dentistry at teeth as they relate to the health of the whole body, in-
the Dental University of Vienna, Austria, that any defi- cluding applicable diagnostic, therapeutic, and rehabil-
ciency or disability in direct aggressive behavior could itation procedures. The conceptual dogmatism of the
be a reason to use the masticatory organ for reducing term gnathology in earlier days was a problem or cause
stress through bruxism. As a result of her research, that split occlusionists from nonocclusionists. But
she found that the total group of 98 bruxers had signif- dogmatic wars are counterproductive. Independent
icantly reduced general well-being. Furthermore, the from skeletal individuality, human teeth are nearly
personality structures in the study were significantly morphologically the same. Canines and anterior teeth
different from standard random samples of matched are controlling and/or guiding; posterior teeth support
groups in regard to general aggressive behavior. In ad- and disclude. The modern gnathologic concept is clearly
dition, both spontaneous and reactive aggressive be- proven and can be recommended. Any other concept in
haviors were markedly less than in the control group. orthodontics must be defined but must fit with the nat-
In the lives of the subjects, problem solving frequently ural morphology of teeth and must be verified by
occurs either in a delayed manner or by way of scientific data.35,36

January 2011  Vol 139  Issue 1 American Journal of Orthodontics and Dentofacial Orthopedics
16 Point

CONCLUSIONS 17. Kail K. Behandlungserfolg bei kiefergelenksbeschwerden in

abh€angigkeit von organischen und psychischen faktoren [disser-
The teeth occlude and determine the motion tation]. Vienna, Austria: Universit€at Wien; 1985.
pattern of the mandible. Furthermore, motion patterns 18. EACD Closed Meeting 1984
occur in the neuromuscular system and are regulated 19. Sato S, Slavicek R. Bruxismus als stressbew€altigungsfunktion des
proprioceptively. The signals of proprioception occur kauorgans. Wien Med Wochenschr 2004 154/23-24: 584-9,
Springer-Verlag.
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20. Hirata Y, Yamamoto T, Kawagoe T, Sasaguri K, Sato S. Rela-
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teeth provide the most rapid information to the brain cervical lesions among male adults. J Stomat Occ Med 2010;
in monosynaptic fashion. The functions of the mastica- 3:10-4.
tory organ are entirely different and closely networked 21. Kato K, Ono Y, Kubo KY, Sasaguri K, Watanabe K, Onozuka M,
et al. Occlusal disharmony suppresses long-term potentiation in
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are strongly linked. terns of intracapsular derangement of TMJ. J Stomat Occ Med
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