antibiotics are usually given. To prevent
spread of the infection, towels, flannels,
and pillowcases should not be shared.
Children shouldnot go to school or mix
with others until they have been treated
for the condition.
implantAny material, either natural or
artificial, inserted into the body for
medical or cosmetic purposes. For exam-
ple, artificialjoints can replace diseased
structures and breast implants can
improve appearance. Implants are also
used to maintain proper functioning of
an internal organ, treat certain disor-
ders, or deliver drugs or hormones.
implantation, eggAttachment of a
fertilized ovum(egg) to the wall of the
uterus. It occurs about 6 days after fertil-
ization, when the blastocyst (early
embryo)comes into contact with the
wall of the uterus. As the cells of the
developing embryocontinue to divide,
the outer cell layer penetrates the lining
of the uterus to obtain oxygen and
nutrients from the mother’s blood; later,
this layer develops into the placenta. The
embryo usually implants in the upper
part of the uterus; if it implants low down
near the cervix, placenta praeviamay
develop. Rarely, implantation occurs out-
side the uterus, possibly in a fallopian
tube, resulting in an ectopic pregnancy.
implant, dentalA post, surgically em-
bedded in the jaw for the attachment of
a dental prosthesis (an artificial tooth).
Titanium or synthetic materials may be
used. A dental implant is fitted under
local anaesthesia. A hole is drilled in the
jaw and a post inserted. Several months
later, an attachment that protrudes from
the gum is screwed into the post; a few
weeks after that, the prosthesis is fitted.
impotenceInability to achieve or main-
tain an erection, usually caused by
psychological factors, including concerns
about performance or relationship diffi-
culties. In about 1 in 10 cases, the cause
is a physical disorder, such as diabetes
mellitus, or a neurological disorder, such
as damage to the spinal cord. Some drugs
cause impotence as a side effect, but this
reverses when the drugs are stopped.
Treatment may include counsellingor
sex therapyfor psychological problems.
The drug sildenafilis used to treat both
organic and psychological impotence, but
side effects may occur. Other treatments
include self-administered injections into
the penis and a surgical implant, which
can produce a sustained erection.
impression, dentalA mould taken of
the teeth, gums, and palate. A quick-set-
ting material, such as alginate, is placed
in a mould over the teeth. The mould is
removed, and plaster of Paris is poured
into it to obtain a model of the area.
This model is then used as a base on
which to build a denture, bridge, or den-
tal inlay. Dental impressions are also
used in orthodonticsto study the position
of the teeth and to make orthodontic
appliancesto correct irregularities.
incestSexual intercourse between close
relatives, such as with a parent, a son or
daughter, a brother or sister, an uncle or
aunt, a nephew or niece, or a grandpar-
ent or grandchild. It is illegal or taboo
in most societies and against the teach-
ing of many religions.
incidenceOne of the 2 principal mea-
sures (the other is prevalence) of how
common a disease is in a defined popu-
lation. The incidence of a disease is the
number of new cases that occur during
a given period (for example, 17 new
cases per 100,000 people per year).
incisionA cut made into the tissues of
the body by a scalpel (surgical knife).
Most incisions are made to gain access
to tissue inside the body, usually to
repair or remove a diseased organ. An
incision may also be made to allow pus
to drain from an abscessor boil.
incisional herniaA type of herniain
which the intestine bulges through aIMPLANT INCISIONAL HERNIA
I
ImplantNatural
tooth
Bone
Artificial toothIMPLANT, DENTALGum