This document discusses the relationship between temporomandibular joint disorder (TMD) and dental occlusion. While some studies have found associations between certain malocclusions and TMD, the majority fail to find significant or consistent correlations. No single occlusal factor appears to be the predominant cause of TMD. The hypothesis that dental occlusion is the sole or primary cause of TMD has not been supported. More research is still needed to fully understand the relationship between malocclusion and TMD.

1. Presented By: Sohaila Ibrahim
Under Supervision of:
Prof. Dr. Maher Fouda

2. Temporomandibular
joint disorder is an
umbrella term covering
acute or chronic
inflammation of the
temporomandibular joint
The disorder and
resultant dysfunction
can result in significant
pain and impairment.

3. Historically, there has been
a belief among certain
members of the dental
profession that dental
occlusal factors have a
strong causal relationship
to (TMD).
The belief in this
association was originally
based primarily on direct
clinical observation, with
little scientific evidence to
support it.

4. Stating that dental
occlusal factors have a
causative role in the
etiology of TMD is a
hypothesis.
However, beginning in the
1980s, a “new” theory of
causation, “multi-
factorial” etiology,
emerged within the
dental profession.

5. If dental occlusion was
the sole or
predominant cause of
TMD it would have
been easy to establish
that relationship by
testing the hypothesis.

6. A number of occlusal factors have been examined in an
attempt to assess their individual effect on TMD.
These have included, skeletal anterior open bite,
overbite, overjet, crossbite, incisor inclination, missing
teeth, posterior occlusal support, balancing-side
interferences, working-side interferences, intercuspal
interferences, symmetry of contacts in the retruded
contact position, and slide between the retruded
contact position and the intercuspal position.
Although some associations have been recognized, in
most studies these have been assessed individually,
not in combinations of two or more.

7. Many studies have
been conducted to try
and determine the
correlation between
malocclusion and
TMD

8. For example, Tuerlings, 2004 stated that few
relationships exist between individual
parameters and TMD signs.
Gesch, 2004 found few associations
between malocclusion and TMD, and
these associations were not uniform.
No particular morphologic or functional
occlusal factor became apparent.

9. Fujita 2004 found that
the TMD symptoms of
the patients with
notable oral habits did
not change or become
worse during a period
of about 5 years.

10. A study conducted by Barker, 2004
where a randomly chosen group
of 60 patients with occlusal
interferences and signs and
symptoms of TMD used a
mandibular orthotic to balance
their occlusions at centric
relation .
When the occlusions of
symptomatic patients were
balanced in CR, there was a
significant reduction or
elimination of TMD complaints,
suggesting a relationship
between balancing occlusion in
CR and optimum management
of TMD.

11. A 20 year follow up study conducted by Egermark in 2003 revealed
that:
• Subjects with malocclusion over a long period of time tended to
report more symptoms of TMD and to show a higher dysfunction
index, compared with subjects with no malocclusion at all.
• There were no statistically significant differences in the prevalence of
TMD signs and symptoms between subjects with or without previous
experience of orthodontic treatment.
• no single occlusal factor is of major importance for the development
of TMD, but a lateral forced bite between retruded contact position
(RCP) and intercuspal position (ICP), as well as unilateral crossbite,
may be a potential risk factor in this respect.
• subjects with a history of orthodontic treatment do not run a higher
risk of developing TMD later in life, compared with subjects with no
such experience.

12. A study by Mohlin in 2002 confirmed earlier
observations that TMD prevention is not a
major motivating factor for orthodontic
treatment.

13. Marzooq in 1999 found that although
occlusal relationships, such as overbite,
non-working side interferences, and
discrepancy between the intercuspal
position and the retruded contact position,
have often been considered as
contributing factors of TMD, there is no
consistency among even those studies
that support such an occlusal factor.

14. Thilander in 2002 observed a sample of 4724
children (5-17 years old) grouped not only by
chronological age but also by stage of dental
development
The prevalences increased during the
developmental stages.
Girls were in general more affected than boys.
Significant associations were found between
different signs, and TMD was associated with
posterior crossbite, anterior open bite, Angle Class
III malocclusion, and extreme maxillary overjet.

15. John in 2002 stated that with 3033 subjects,
his study provided the strongest evidence
to date that there was no association
between overbite or overjet and self-
reported TMD.

16. In a study conducted by Gaudet in 2000 no
data was found to support the hypothesis
that TMD patients improve spontaneously
without treatment.

17. Fushima in 1999 found that midline
discrepancy and right-left difference of the
molar relationship seem to be important
occlusal characteristics in patients with
TMD.

18. Associations between certain
malocclusions and TMD were found in
some studies,
whereas the majority failed to identify
significant and clinically important
associations.
TMD could not be correlated to any specific
type of malocclusion,

19. A considerable
reduction in signs and symptoms of TMD
between the teenage period and young
adulthood has
been shown in some recent longitudinal
studies.
However, there is still a need for ore
studies