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WINTER 2014
I
t is not uncommon for divers to complain of
pain or tenderness in the jaw, a headache or
aching facial pain after diving. The gripping
action required to hold a mouthpiece in place
may strain the muscles used for chewing (masticatory
muscles) or the temporomandibular joint (TMJ), which
connects the jaw (mandible) to the temporal bone. Pain
associated with the TMJ and masticatory muscles is
known as temporomandibular dysfunction (TMD).
“During diving, the TMJ is subjected to a stress equal
to what you would experience if you kept your mouth
open — not fully, but as if you stuck three fingers into
it vertically — during the entire dive,” said Costantino
Balestra, Ph.D., vice president of research and education
at DAN Europe. “This acts on the retromeniscal
neurovascular bundle and can cause myalgia or headache.
By having a customized mouthpiece molded, this can
be reduced or even eliminated.” Balestra is the lead
author of the study “Scuba diving can induce stress of the
temporomandibular joint leading to headache,” published
in the British Journal of Sports Medicine in 2004.
The most common mouthpiece designs feature
an elliptical airway attached to the demand valve,
a labial flange to provide stability and a platform
the diver bites for retention. Mouthpieces generally
feature short bite tabs and are made of a soft material
to accommodate use by a wide range of jaws and
teeth; this requires forward movement of the jaw
to effectively grip the mouthpiece. This design may
not support posterior occlusion, which is the most
effective contact of the molar and bicuspid teeth of
both jaws for allowing the natural movements of the
jaws essential to normal chewing and closure. This
lack of support may result in uneven loading of the
TMJ. Cold water may exacerbate this problem by
impairing a diver’s ability to use his or her lips to
properly grip the mouthpiece.
UNDERSTANDING TMD
The TMJ is one of the most complex joints in the
body; its movement involves a combination of hinging
and sliding action. To locate it, place a finger directly
in front of your ears. Move your jaw from side to side,
or open and close your mouth. You can actually feel
the mandible moving in and out of the TMJ socket.
The upper section of the joint is a depression in the
temporal bone of the skull; the lower section of the
joint is the mandibular condyle, a rounded projection
at the upper tip of the mandible. These bones, which
make up the joint, are covered in cartilage and are
separated by a small disc, which facilitates smooth
opening, closing and side-to-side movements.
In many cases, the cause of TMD is not clear. TMD
may occur if this disc erodes or becomes improperly
aligned, if the cartilage is damaged by arthritis or
if the joint is subjected to trauma or long-term
microtraumas. Researchers are still seeking to fully
understand the causes of these conditions and what
treatments are most effective.
Reported symptoms include:
• pain or tenderness in the TMJ
• TMJ clicking or crepitus (cracking or
popping sound)
• discomfort while chewing
• difficulty opening or closing the mouth
• facial pain
• headache
• blockage of Eustachian tubes
• vestibular disturbances such as vertigo or
disorientation (either of which could be
hazardous should it occur underwater)
Several studies have noted more women reporting
TMD symptoms than men. The average age of
onset is between 20 and 40, but this dysfunction
may occur at any age. In their study “Prevalence of
temporomandibular dysfunction in a group of scuba
divers,” Aldridge and Fenlon suggest that this may be
related to anatomical differences such as mandibular
angulation and masticatory muscle insertion.
Scuba diving does not appear to cause TMD;
however, it may exacerbate a preexisting joint
condition. “The problem is that there are many people
B Y M A U R E E N R O B B S
RESEARCH, EDUCATION & MEDICINE
//
S A F E T Y 1 0 1
Temporomandibular Joint
Dysfunction in Diving
