CRISIS
CROW N, DENTAL
crisis
A term for a turning point in the
course of a disease (either the onset of
recovery or deterioration), or for a dis-
tressing and difficult episode in life.
crisis intervention
The provision of
immediate advice or help by a variety of
agencies such as social services depart-
ments to people with acute personal or
sociomedical problems.
critical
A term used to mean seriously ill
or to describe a crucial state of illness
from which a patient may not recover.
Crohn's disease
A chronic inflamma-
tory disease affecting the
gastrointestinal
tract
.
In young people, Crohn's disease
usually affects the
ileum
, causing spasms
of abdominal pain, diarrhoea, loss of
appetite,
anaemia
, weight loss, and
mal-
absorption
.
In elderly people, the
rectum
is more often affected, causing rectal
bleeding. In both groups, the disease
may also affect the
anus
, the colon and,
rarely, the mouth,
oesophagus
, stom-
ach, and
duodenum
.
Complications include obstructions in
the intestine; chronic abscesses; inter-
nal
fistulas
(abnormal
passageways)
between intestinal loops; and external
fistulas from the intestine to the skin of
the abdomin skin or around the anus.
Complications in other parts of the
body may include inflammation of the
eye, severe
arthritis
in various joints,
ankylosing spondylitis
, and skin disor-
ders (including
eczema
).
Investigatory procedures may include
sigmoidoscopy
and X-rays using barium
(see
barium X-ray examinations
).
Colon-
oscopy
and
biopsy
may help distinguish
the disease from
ulcerative colitis
.
Sulfasalazine
and related drugs, and
corticosteroid drugs
may be prescribed.
A high-vitamin, low-fibre diet may be
beneficial. Acute attacks may require hos-
pital treatment, and many patients need
surgery. The symptoms fluctuate over
many years, eventually subsiding in some
patients. If the disease is localized, a
person may remain in normal health.
crossbite
A type of
malocclusion
in
which some or all of the lower front
teeth overlap the upper front teeth.
cross-eye
A type of
strabismus
(squint)
in which one or both eyes turns inwards
relative to the other.
cross-matching
A procedure to deter-
mine compatibility between the blood
of a person requiring a
blood transfusion
and that of a
donor
. Red blood cells from
one person are combined with
serum
from the other. Clumping of red blood
cells indicates the presence of
antibodies
,
showing the blood is not compatible.
croup
A common condition in infants
and young children in which narrowing
and inflammation of the airways causes
hoarseness, stridor (a grunting noise
during breathing), and a barking cough.
Croup may be caused by a viral or bac-
terial infection that affects the
larynx
,
epiglottis (see
epiglottitis
),
or
trachea
.
Other causes include
diphtheria
,
allergy
,
spasm caused by deficient
calcium
in the
blood, and inhalation of a
foreign body
.
Most cases are due to a viral infection
and are mild.
Humidifying the air can help to make
breathing
easier.
Nebulized
cortico-
steroid drugs
(see
nebulizer
) and oxygen
may be prescribed. Infections are treat-
ed with
antibiotic drugs
.
crowding,
dental
See
overcrowding,
dental
.
crown, dental
An artificial replacement
for the crown of a
tooth
that has be-
come decayed, discoloured, or broken.
A porcelain crown is usually used on
front teeth, but back teeth require the
greater strength of a crown made from
gold or porcelain fused to metal.
A crown may be fitted by filing the nat-
ural tooth to form a peg and cementing
the crown over the top. If the tooth is
CROWN, DENTAL
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