I
and X-rays are taken; the dye outlines
the shape of the structure. Anything that
protrudes into the cavity of a body
structure, such as
polyps
in the large
intestine or a tumour in the bladder,
w ill prevent the area from filling with
the contrast medium, and w ill produce
a distorted shape on the X-ray.
filling, dental
The process of replacing a chipped or
decayed area of tooth w ith an inactive
material. The term may also be used to
describe the restorative material itself.
Amalgam, a hard-wearing mixture of
silver, mercury, and other metals, is
often used for back teeth. Tiny amounts
of mercury released from such fillings
are believed by some to cause health
problems. However, a link has yet to be
scientifically established.
If a front tooth is chipped, bonding
(see
bonding, dental
) ,
in w hich plastic or
porcelain
tooth-coloured
material
is
attached to the surface of the tooth,
may be used.
WHY IT IS DONE
W hen enamel is damaged, bacteria can
invade the dentine beneath and even-
tually attack the pulp
(inner tissue
containing blood vessels and nerves),
causing the tooth to die. Teeth are
therefore repaired, where possible, at
the first signs of damage to prevent
decay Filling also restores a tooth’s
original shape, w hich is important for
appearance and also for a correct bite.
HOW IT IS DONE
If the filling required is large or in a
sensitive area, the dentist numbs the
surrounding gum w ith a local anaes-
thetic
(see
anaesthesia, dental
) .
Any
soft, decayed material is removed with
sharp instruments. A high-speed drill
is used to remove harder material and
to shape a hole that w ill hold the fill-
ing securely. W hile the dentist works, a
suction tube placed in the patient’s
mouth draws away saliva and produces
water to cool the end of the drill.
If the pulp is almost exposed, the
bottom of the cavity is lined w ith a
sedative paste to protect the sensitive
pulp from pressure and temperature
changes. If one or more of the walls of
the tooth is missing through extensive
decay, a steel band may be
placed
around the tooth to support the filling.
The dentist then mixes the amalgam or
other filling material, and packs it into
the cavity, smoothing the surface. The
material hardens over 24 hours.
FINGER
OUTLOOK
Amalgam fillings have a lim ited life
and may need to be replaced after
about ten years. Occasionally, a filling
needs to be replaced sooner if decay
has spread under the filling or the fill-
ing has become dislodged or fractured.
film
A thin, transparent sheet of cellulose
acetate or similar material, coated with
a light- or
radiation
- s e n s i t i v e
emulsion, on
which images such as
X-rays
are produced.
The term is also used to describe any thin
layer or coating, such as the covering of
tears
on the eyeball. (See also
blood film
.)
film badge
A device that enables hospital staff to
m onitor their
exposure to
radiation
.
Film badges are w orn by people w ork-
ing in
X-ray
and
radiotherapy
depart-
ments. The badge consists of a piece of
photographic film in a holder, w hich is
w orn on the clothing. The film has a
fast (sensitive) emulsion on one side
and a slow emulsion on the other.
Small doses of radiation blacken only
the fast emulsion; higher doses start to
blacken the slow emulsion and make
the fast emulsion turn opaque.
fimbriae
A fringe of threadlike or fingerlike fila-
ments, such as those that make up the
ends of the
fallopian tubes
that open on
to the ovaries (see
ovary
) .
During
ovula-
tion
,
the fimbriae guide the egg (see
ovum
) into the tube.
finasteride
A specific
enzyme
inhibitor drug that
prevents the conversion of
testosterone
into the more potent male hormone
dihydrotestosterone. Finasteride is used
in the treatment of noncancerous en-
largement of the prostate (see
prostate,
enlarged
); it shrinks the gland, thereby
improving urine flow. It is also used to
treat male pattern baldness in men. Side
effects include
impotence
and reductions
in
libido
and
semen
volume.
fine tremor
A
tremor
(an involuntary trembling or
oscillating
movement)
characterized
by very small and rapid vibrations.
finger
One of the digits of the
hand
.
Each fin-
ger has three phalanges (finger bones),
and the thumb has two. The phalanges
join at hinge joints moved by muscle
tendons that flex (bend) and extend
(straighten) the finger. The tendons are
covered by synovial sheaths that con-
tain
fluid,
enabling
the
muscles
to
w ork without friction. A small artery,
vein, and nerve run down each side of
the
finger.
The
entire
structure
is
enclosed in skin w ith a
nail
at the tip.
DISORDERS
Finger injuries are common, especially
lacerations
,
fractures
,
and ruptures of
the tendons.
Mallet finger
is a condition
that occurs when the extensor tendon
along the back of the finger is pulled
away from its attachment after a blow
to the fingertip.
Infections may occur in the finger
pulp at the tip;
paronychia
(infection of
the tissue around a nail) sometimes
follows a m inor cut.
Inflammation that is due to
rheuma-
toid arthritis
or
osteoarthritis
may affect
the joints of the fingers, causing stiff-
ness, pain, swelling, and deformity. In
addition, the flexor tendons, w hich
run along the front of the fingers, may
become
inflamed and stuck
in the
tendon
sheath,
causing
a
condition
known as
trigger finger
.
Altered control of the muscles in the
walls of the blood vessels and impaired
blood supply to the hands and fingers
may cause
Raynaud’s disease.
Dactylitis is
a spindle-shaped swelling of the fingers
F
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