AD 2017 Q3

middle-ear space over the course of the dive. Postdive,
the tissues metabolize the oxygen, reducing the total
gas volume below what it would be if the space were
filled with air. If this loss in gas volume is not equalized,
relative negative pressure will develop. This is in effect
a squeeze, which can present as ear fullness, mild
discomfort and/or impaired hearing.
This problem can be avoided easily with occasional
equalization for several hours after diving. A person
who is active, talking and/or laughing during this
period may have no need to actively equalize. On the
other hand, a person who goes to bed immediately
after diving might wake up several hours later with
mild discomfort. Full resolution is best achieved using
gentle equalization techniques.
— Neal W. Pollock, Ph.D.
ISTOCKPHOTO.COM
Q:
I’m 20 years old and will be having four
wisdom teeth (third molars) removed soon.
I understand I’ll have air pockets where
my teeth were, and I assume those could cause
problems while diving. How long should I stay out
of the water?
A:
Following an uncomplicated dental extraction,
four to six weeks is normally sufficient time
for the risk of infection to resolve. This
assumes good healing and that gum tissue has filled
in the empty sockets, eliminating any air pockets. An
unhealed socket can be a route for infection as well as
for air to enter subcutaneous tissues and cause further
injury. Pain medication can impair your judgment
underwater, so wait at least a couple of days after you
finish taking it to resume diving.
Following the extraction of upper wisdom teeth,
the dentist should verify that there is no sinus
involvement. The root tip of a molar can breach the
maxillary sinus floor, resulting in a communication
(abnormal connection) between the mouth and the
sinus. This is not common, but if it occurs it will
further delay your return to diving. If there is sinus
involvement, you should wait until the fistula (hole)
is closed and healed before you resume diving. Your
dentist or oral surgeon will be able to tell you how long
this should take.
Discomfort, tenderness or delayed healing can make
it difficult to hold a regulator mouthpiece, depending
on the tooth or teeth involved and the length of the
mouthpiece’s flanges. After your dentist or endodontist
approves a return to diving, consider taking your scuba
gear to a local pool. Swim laps underwater to confirm
that breathing through your regulator does not cause
any discomfort.
— Frances Smith, MS, EMT-P, DMT
Q:
A few days ago on a dive boat I heard the
captain say to the group something to the
effect of, “Stay hydrated — dehydration is
the No. 1 cause of DCS.” Is this true?
A:
While dehydration can be a risk factor for
DCS, it is almost certainly not the most
important. The dive profile is the leading risk
factor. The timing and intensity of exercise and thermal
status are likely to play the lead secondary roles.
State of hydration is no more than a tertiary factor
— convenient to blame, but generally less dramatic
in impact. This is not to say that hydration should be
ignored, just that it must be kept in perspective.
Drinking an excessive amount of fluid will not
eliminate the risk of DCS and can even work against
safety by increasing a diver’s susceptibility to immersion
pulmonary edema. As with most things, extremes in
either direction can be hazardous. Sound hydration
is important for general health and diving health,
but ignoring the elephant in the room (the depth/
time profile) and factors such as ill-timed thermal and
exercise stress is definitely not good practice.
— Neal W. Pollock, Ph.D.
STEPHEN FRINK
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