I
DEPO-PROVERA
dentistry
The science or profession concerned
with the teeth and their supporting
structures. Most dentists work in general
dental practice; others practise a spe-
cialized branch of dentistry.
Dentists in general practice under-
take all aspects of dental care. They may
refer patients to a consultant in one of
the specialized branches of dentistry,
such as
orthodontics
(correction of the
alignment of teeth),
prosthetics
(fitting
of bridgework and dentures),
endo-
dontics
(treatment of diseases of the
tooth pulp), and
periodontics
(treatment
of disorders affecting the tissues sup-
porting the teeth).
Dental hygienists carry out scaling
(removal of hard deposits on the teeth)
and demonstrate methods to keep the
teeth and gums healthy.
dentition
The arrangement, number, and type of
teeth in the mouth. In young children,
primary dentition comprises
20
teeth
(incisors, canines, and molars). These
teeth are replaced between the ages of
6
and 13 years by the secondary (perma-
nent)
dentition.
Secondary
dentition
comprises 3 2 teeth (incisors, canines,
premolars, and molars). Often, the third
molars (wisdom teeth)
do not erupt
until the age of 18-25, or even older in
some
cases;
sometimes, they fail to
erupt at all. (See also
eruption of teeth
. )
denture
An
appliance
that
replaces
missing
natural teeth. A denture consists of a
metal and/or acrylic (hard plastic) base
that is mounted with acrylic teeth. The
artificial teeth are matched to the per-
son’s original teeth. Denture baseplates,
w hich are created from impressions
taken from the upper and lower gums,
fit the mouth accurately.
deodorant
A substance that removes unpleasant
odours, especially body odours.
deossification
The loss or removal of
bone
tissue, as in
osteoporosis
.
(See also
ossification
. )
deoxygenation
In
respiration
,
the release of
oxygen
from
red
blood cells
to supply other tissues.
deoxyribonucleic acid
See
DNA
;
nucleic acids
.
dependence
Psychological or physical reliance on
persons or drugs. An infant is dependent
on its parents, but, as he or she grows,
this dependence normally wanes. Some
adults never become fully independent
(see
dependent personality
) .
Alcohol and drugs may induce phys-
ical or emotional dependence in users;
a person w ho has a dependency may
develop physical symptoms, such as
sweating or abdominal pains, or become
distressed if deprived of the drug. (See
also
alcohol dependence
;
drug dependence
. )
dependent oedema
A form of
oedema
(the accumulation of
fluid
in
body
tissues)
that
mainly
affects the lower parts of the body. It
may be a feature of congestive
heart fail-
ure
.
Oedema affecting the ankles may
have various possible causes, such as
immobility,
varicose veins
,
and
pregnancy
.
dependent personality
A
personality disorder
characterized by
an inability to function without signifi-
cant guidance from others, feelings of
helplessness when alone or when close
relationships end, and a fear of separa-
tion. Other features of a dependent
personality include difficulty in making
decisions, low self-esteem, and hyper-
sensitivity to criticism.
Dependent
personality
disorder
is
of unknown cause and normally first
manifests
itself in
early
adulthood.
There is no specific treatment for the
condition, but
psychotherapy
may grad-
ually help sufferers to make their own
choices. Medication, for example with
antianxiety drugs
or
antidepressant drugs
,
may sometimes be effective in relieving
associated symptoms.
depersonalization
A state of feeling unreal, in w hich an
individual has a sense of detachment
from self and surroundings. Deperson-
alization
is
frequently
accompanied
by
derealization
,
in w hich the w orld is
experienced as unreal. It is rarely seri-
ous and usually comes on suddenly and
may last for moments or for hours.
Depersonalization most often occurs in
people
w ho
have
anxiety
disorders
.
Other causes include certain drugs and
temporal lobe epilepsy
.
depilatory
A chemical hair remover, such as barium
sulphide, supplied as a cream and applied
for cosmetic reasons or to treat
hirsu-
tism
(excessive hairiness in women).
Depixol
A
brand
name
for
flupentixol,
an
antipsychotic drug
used in the treatment
of
schizophrenia
and other related ill-
nesses. The drug may be given either
orally or by injection. Possible adverse
effects include an increased risk
of
parkinsonism
(a set of neuromuscular
symptoms including tremors, muscle
rigidity, and slow movements).
Depo-provera
A brand name for
medroxyprogesterone
,
a long-acting
progestogen drug
that is
given by
depot injection
as a contraceptive.
It is sim ilar to
progesterone hormone
,
a
natural female sex hormone.
D
TYPES OF DENTURES
Partial dentures
Partial dentures are used when only some of the teeth are missing. They fill unsightly gaps,
make chewing easier, maintain clear speech, and keep the remaining teeth in the correct
position. Teeth on either side of a gap may tip (making cleaning more difficult) or drift (placing
unnatural stress on the tissues ofthe mouth). Partial dentures are held in place by metal clasps
that grip adjacent teeth or by clasps combined with metal rests (extensions ofthe denture plate
that rest on the surface ofthe tooth).
Full dentures
Full dentures are needed when there are no teeth left in the mouth. They stay in place by resting
on the gum ridges and, in the case of upper dentures, by suction. Fitting is sometimes delayed
after extraction of teeth to allow the gums to shrink and change shape as they heal.
Immediate dentures
Immediate dentures are fitted immediately after extraction of teeth. They protect the gum and
control bleeding from extraction sites. Since a toothless period is avoided, they are particularly
useful for replacing frontteeth. However, they can be expensive and require follow-up visits so
that they continue to fit comfortably. They may also need replacing within a short time.
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