- See more at: http://www.alertdiver.com/?articleNo=1697#sthash.8AFzKki4.dpufTemporomandibular Joint Dysfunction in DivinBy Maureen Robbs
It 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
"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
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
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
Scuba diving does not appear to cause TMD; however, it may exacerbate a
preexisting joint condition. "The problem is that there are many people
who have silent or undiagnosed conditions or just plain flimsy joints, which
only become symptomatic when the stress of holding a traditional mouthpiece is
imposed," said Dr. Randall Moles, orthodontic specialist and developer of
the SeaCureTM custom mouthpiece (one of several commercially available custom
mouthpieces). "So there is a group of people who will have no TMD symptoms
prior to diving who can develop TMJ problems because they had weak joints or a
preexisting subclinical problem."
What You Can Do
Divers who experience jaw pain or other
TMD symptoms should seek a dental consultation and may wish to try equipment
modifications such as a swivel adaptor or a custom mouthpiece. There are a few
styles of standard mouthpieces designed for scuba diving. When selecting your
diving equipment, try several mouthpieces to find the style and size that fits
you best. For added comfort, some divers add a second-stage swivel adaptor to
their regulator that adjusts to subtle head movements and reduces hose tug.
Some regulators incorporate this adaptor as standard design.
If you experience symptoms of TMD during or after diving, seek a dental
consultation. While most cases of diving-associated TMD resolve spontaneously,
your dental professional can recommend management strategies such as muscle
relaxation exercises, techniques for reducing stress or, if necessary, medical
intervention. Your dentist can also advise or assist in the development of a
custom-fitted mouthpiece, which requires less muscular effort for retention
than the traditional design. (There are also commercially available custom
mouthpieces that do not require a dental consultation).
"The dive industry has tried to
make a mouthpiece that will fit everyone, and in doing so they had to make it
soft and short due to the variability of teeth and jaws," Moles said.
"A customized mouthpiece is molded to fit one person and can be made out
of a stiffer material that goes to the back of the mouth, which transfers the
weight of the regulator to the back — where the muscles are. This provides
leverage and greatly reduces the force needed to keep the mouthpiece in place.
In addition, because the mouthpiece can be made of a much stiffer material, it
retains the bite marks that grip the teeth instead of the diver having to
constantly bite down to get a grip on the soft spongy material of the standard
If you opt for a custom-fitted mouthpiece, consider the proper positioning for
a diver. "There is a common mistake made during the molding: People keep
their head in the neutral position," Balestra noted. "This will not
mold the mouthpiece correctly; instead the individual should position his head
as if he was diving, tilting the head backward."
you decide to swap your mouthpiece for a custom one, make sure your new
mouthpiece fits your regulator's second stage. Not every mouthpiece fits every
regulator, and an ill-fitting mouthpiece could incur leakage or decouple from
the regulator. In addition, when attaching your mouthpiece with a cable tie,
confirm tightness, and use a razor blade to cut off excess and ensure there are
no sharp ends.
Do not use a customized mouthpiece on an air source that might be handed off to
a buddy in an emergency; it may make breathing difficult or be impossible for
another diver to use.