PERIMETRY
PERIPHERAL VASCULAR DISEASE
perimetry A visual field test to deter-
mine the extent of peripheral vision.
(See
eye, examination of.)
perinatal Relating to the period just
before or just after birth. The perinatal
period is often defined as the period
from the 28th week of pregnancy to the
end of the
1
st week after birth.
perinatology A branch of
obstetrics
and
paediatrics
concerned with the study and
care of the mother and baby during preg-
nancy and just after birth.
perineum The area bounded internally
by the pelvic floor (the muscles that sup-
port the pelvis) and the surrounding
bony structures. Externally, the perineum
is the area that lies behind the genitals
and in front of the anus.
periodic fever An inherited condition
causing recurrent bouts of fever. (See
familial Mediterranean fever.)
period, menstrual See
menstruation.
periodontal
disease Any disorder of
the periodontium (the tissues that sur-
round and support the
teeth
).
periodontics The branch of
dentistry
concerned with
periodontal disease
.
periodontitis Inflammation of the peri-
odontium (the tissues surrounding the
teeth
). There are 2 types: periapical and
chronic. Periapical periodontitis results
from neglected dental
caries
and occurs
when bacteria enter the tooth pulp and
spread to the root tip, sometimes caus-
ing a dental
abscess
,
granuloma
, or
cyst.
Chronic periodontitis is a result of un-
treated
gingivitis
, in which bacteria attack
the periodontal tissues. This type is the
major cause of adult tooth loss.
Periapical periodontitis may cause
toothache, especially on biting. An ab-
scess may make the tooth loose; a large
dental cyst may cause swelling of the
jaw. In chronic periodontitis, the signs
of gingivitis are present.
Periodontitis is diagnosed by a dental
examination and dental
X-rays
. Periapi-
cal periodontis is treated by draining pus
and filling the tooth or by
extraction.
Regular teeth cleaning can prevent
advanced chronic periodontal disease
and further destruction of the tissues.
Treatment may include root planing,
scaling
,
gingivectomy
, or curettage (see
curettage, dental
).
Sometimes, loose
teeth can be anchored to firmer teeth
by splinting (see
splinting, dental
).
period pain See
dysmenorrhoea.
periosteum The tissue that coats all of
the
bones
in the body except the joint
surfaces. The periosteum contains small
blood vessels and nerves, and produces
new bone in the initial stages of healing
following a
fracture.
STRUCTURE OF BONE
periostitis Inflammation of the
perios-
teum
. The usual cause is a blow that
presses directly on to bone. Symptoms
include pain, tenderness, and swelling
over the affected area.
peripheral nervous system All the
nerves that fan out from the
central ner-
vous system
to
the
muscles, skin,
internal organs, and glands (see
nerve
;
cranial nerves
;
spinal nerves
).
peripheral vascular disease Narrow-
ing of blood vessels in the legs, and
sometimes
in
the
arms, restricting
blood flow and causing pain. In severe
cases,
gangrene
may develop. In most
affected people, peripheral vascular dis-
ease is caused by
atherosclerosis
. The
greatest risk factor is
smoking.
Diseases
of the peripheral vessels that are not
caused by atherosclerosis include
Buer-
ger's disease, Raynaud's disease, deep
vein thrombosis,
and
varicose veins.
The first symptom of narrowed arter-
ies due to atherosclerosis is usually an
aching feeling in the leg muscles when
walking, which is relieved by resting.
Pain recurs after the same amount of
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