|
anchorage |
resistance to unwanted tooth movement caused by the reactive
component of an orthodontic force; refers also to the intra-
and extraoral structures that supply the resistance
|
|
angulation |
the tilt
of the long axis of a tooth in a mesial or distal direction;
see inclination
|
| anterior
crossbite |
one or more
teeth in the maxillary anterior segment is lingual to one or
more of the opposing teeth in the mandibular anterior
segment in maximum intercuspation |
| anterior
segment |
all of the
canine and incisor teeth in a given dental arch |
|
arch wire |
a wire applied
to two or more teeth through fixed attachments to cause or
guide orthodontic tooth movement |
| arch
circumference or arch
perimeter |
the
distance from the mesial contact of one first permanent
molar to its antimere as measured through the contact points
or buccal cusp tips of all of the intervening teeth,
ignoring those teeth that are malpositioned or blocked out
so that the measurement represents an ideal arch form; see
arch length
|
| arch depth
|
the
perpendicular distance from a point between the central
incisors to a line connecting the mesial contacts of the
first permanent molars; see
arch length |
|
arch length |
same as arch
depth; but note that 'arch length' is often used as a
synonym for arch circumference or arch perimeter
|
| band
|
a circular
metal strip that is adapted to fit closely around a tooth;
various components of an orthodontic appliance may be welded
or soldered to it |
| base,
bracket |
the part of a
bracket that is attached either to a metal band or bonding
pad |
| bimaxillary
|
both the upper
and lower jaw |
| blocked out
|
a tooth that is
positioned away from its proper position in the dental arch
due to insufficient space |
| bonding pad
|
the retentive
portion of a fixed orthodontic attachment which locks it
mechanically to the bonding material; the pad usually has a
fine mesh surface |
|
bracket |
a metal,
plastic, or ceramic fixed attachment which holds an
arch wire
|
| buccal tube
|
a fixed
attachment which is open only at each end. Tubes may be
round or rectangular in cross section; round tubes are
usually .045 inches in diameter to receive auxiliaries such
as a facebow or lip bumper, rectangular tubes are either
.018 x .025 or .022 x .028 inches in order to receive
arch wires and generally are placed on the
most distal molar tooth in the appliance. |
| buccal
segment |
all of the
premolar and molar teeth in a given quadrant |
|
cell-free zone
|
descriptive term for the necrosis that occurs in a pressure
zone of the periodontal ligament (PDL) as a result of
excessive orthodontic force; the same as
hyalinized zone
|
|
center of resistance
|
considering the
tooth in its alveolus, it is that point through which a pure
force would result in translation of the tooth without any
rotational effect; for a given tooth the center of
resistance is found at approximately one-third (0.3 to 0.5)
of the distance from the alveolar crest to the apex, and its
location does not change (unless root length or alveolar
crest height changes) |
|
center of rotation
|
a point around
which all points on the tooth rotate; the center of rotation
can change depending upon the forces and moments acting upon
the tooth |
|
cervical-pull headgear
|
a
headgear that uses a cervical neck strap as anchorage,
thus directing the reaction force of the headgear force
module to a site that is outside the oral cavity; the
direction of the force on a maxillary molar is backward and
downward |
| Class I
malocclusion (Angle) |
a malocclusion
with correct mesiodistal relationship of the first permanent
molars |
|
Class II malocclusion
(Angle) |
a malocculsion
in which the lower first permanent molar is positioned
distally relative to the upper; see
distoclusion . To classify a unilateral Class II
malocclusion, see subdivision .
|
|
Class III malocclusion
(Angle) |
a malocculsion
in which the lower first permanent molar is positioned
mesially relative to the upper; see
mesioclusion . To classify a unilateral Class III
malocclusion, see subdivision .
|
| couple
|
a couple is
produced when two equal and opposite forces act on a body;
the magnitude of the couple is equal to the product of one
of the forces times the perpendicular distance between the
forces |
|
cranial index
|
the ratio of
maximum cranial breadth (measured wherever found) to maximum
cranial length (glabella to opisthocranium), expressed as a
percentage |
| crowding
|
exists
when the sum of the mesiodistal widths of the teeth in an
arch exceeds the arch
circumference |
| dental (dentoalveolar)
malocclusion |
a malocclusion
characterized by deviation from normal in the teeth and
their supporting tissues; the size, shape and position of
craniofacial bones is within the normal range |
| diagnostic
setup |
teeth are cut
from a plaster cast and repositioned with wax; setups are
used to evaluate alternative treatment plans |
|
direct resorption
|
removal
of the cortical bone of the alveolar wall by clast cells in
the periodontal ligament of a tooth being moved by an
orthodontic force; note that this is not possible in a
cell-free zone
compare to
undermining resorption
|
|
distoclusion
|
distal
position of the lower buccal teeth in relation to the upper;
see Angle Class II
|
| division 1
|
an
Angle Class II malocclusion in which the
maxillary incisors are positioned forward in relation to the
lowers resulting in marked overjet |
| division 2
|
an
Angle Class II malocclusion in which the
maxillary incisors are in close relation to the lowers,
usually with a deep overbite |
| E space
|
the difference
between the mesiodistal widths of the primary second molar
and the second premolar; generally the second premolar is
smaller than the primary second molar |
| ectopic
eruption |
any tooth can
erupt ectopically; when applied to the maxillary first
permanent molar it describes a condition wherein the
permanent molar erupts with excessive mesial angulation,
resulting in resorption of the second primary molar and lack
of full eruption of the first permanent molar |
| elastic
limit |
the maximum
stress a wire or spring can withstand without permanent
deformation |
| extrusion
|
displacement of
a tooth along its long axis out of the alveolus; sometimes
called forced eruption |
|
facebow |
the wire
portion of an orthodontic headgear ,
consisting of an inner and outer bow; the inner bow is
connected to the teeth by means of a round tube on an
orthodontic band, or by a 'J' hook to an arch wire, the
outer bow is connected to a neck strap or
headcap by an interposed force module
|
|
facial index
|
the ratio of
facial height (nasion to gnathion) to zygomatic breadth (
zygion to zygion), expressed as
percentage |
| functional
shift |
the mandible
moves excessively from initial contact position to maximum
intercuspation, usually resulting in an anterior (forward
shift) or posterior (lateral shift) crossbite |
| glabella
|
most anterior
point on the midsagittal plane between the superciliary
arches; on the living it is found above the root of the nose
between the eyebrows |
|
headcap |
that portion of
an orthodontic headgear that rests on a portion of the
occipital part of the cranium, thus directing the reaction
force of the headgear force module to a site that is outside
the oral cavity; the direction of the force on the maxillary
molar is backward or backward and upward (see
neck strap ) |
|
headgear |
an apparatus
that is used to deliver force to the teeth from outside the
oral cavity; it consists of three parts: a
facebow , a headgear
force module and a neck strap or
headcap (see high-pull
, occipital-pull , and
cervical pull headgear ) |
|
headgear force module
|
the source of
force for an orthodontic headgear; it may consist of an
elastic strap or rubber bands, but modern "safety" headgear
typically use a small plastic part with an internal spring
that is designed to "breakaway" if the facebow is pulled
forward |
|
high-pull headgear
|
a
headgear that is arranged so that the direction of the
force is markedly upward and backward; this apparatus uses a
headcap as anchorage |
| ideal
occlusion |
no malocclusion
present |
| impacted
|
a tooth that
has failed to erupt into the oral cavity; in orthodontics
this often describes maxillary canines and third permanent
molars that occupy a position from which normal eruption is
highly unlikely |
|
inclination |
the tilt
of the long axis of a tooth in the buccolingual or
faciolingual direction; see
angulation |
|
infraocclusion |
a tooth or
teeth positioned below the plane of occlusion |
|
intermaxillary |
between the
upper and lower jaws |
| intrusion
|
displacement of
a tooth along its long axis into the alveolus |
| leeway space
|
the difference
between the mesiodistal widths of the primary canine, first
and second primary molars and the permanent canine, first
and second premolars |
|
leptoprosopic
|
a high,
narrow face with a facial index of 90 or more; see
facial index
|
| ligature
|
a tie used to
secure the brackets on individual teeth to an orthodontic
arch wire; usually made of wire or elastic material --
ligatures may also be used to secure removable lingual
arches, lip bumpers, etc. in their respective attachments.
|
|
load-deflection rate
|
force per unit
displacement of a spring; the lower the rate, the smaller
the force developed for a given amount of displacement, and
vice versa |
| moment of a
force |
an applied
force tends to produce a turning effect or rotation on the
body on which it acts; the magnitude of the moment is equal
to the product of the force times the perpendicular distance
from the line of action of that force to the point around
which the rotation occurs (see center of
rotation ) |
|
neck strap |
that
portion of an orthodontic headgear that
rests on the back of the neck, thus directing the reaction
force of the headgear force module to a site that is outside
the oral cavity; see
cervical-pull headgear |
|
neutroclusion |
normal
mesiodistal occlusal relationships of the buccal teeth
|
|
nickel-titanium or Ni-Ti |
arch
wires made of a nickel-titanium alloy which deliver a much
lower force for a given amount of deflection than comparable
wire made of resilient stainless steel; see
load-deflection rate
|
| normal
occlusion |
optimal
occlusion as it exists in real life; minor irregularities
may be present |
|
occipital-pull headgear
|
a
headgear that is arranged so that the direction of the
force is mostly backward; this apparatus uses a headcap as
anchorage |
| open bite
|
a malocclusion
in which some teeth cannot be brought into contact with
opposing teeth and no vertical overlap is present
|
| open bite,
functional |
failure of
incisors to contact in maximum intercuspation even though
vertical overlap is present |
| orthodontic
appliance |
any device used
to move teeth or influence the shape of the jaw |
| orthognathic
surgery |
surgical
repositioning of one or both jaws; usually done concurrently
with orthodontic repositioning of the teeth |
| overbite
|
vertical
overlap of upper teeth over lower teeth; usually refers to
incisors |
| overjet
|
horizontal
projection of upper teeth beyond the lower teeth; usually
refers to incisors; in Class III malocclusion incisor
overjet may be recorded as negative |
| posterior
crossbite |
one or more
teeth in the maxillary buccal segment is lingual to one or
more of the opposing teeth in the mandibular buccal segment
in maximum intercuspation |
| pressure
zone |
that part
of the periodontal ligament that is compressed as a result
of an applied orthodontic force; see
cell-free zone |
| primate
space |
in the primary
dentition, a space mesial to the maxillary primary canines
and distal to the mandibular primary canines |
| proclined
|
a forward
inclination of an incisor tooth, usually determined from a
cephalometric analysis; see inclination |
| protraction
|
anterior
movement of teeth |
| protrusive
or procumbent |
a forward
position of an incisor tooth, usually determined from a
cephalometric analysis |
|
reproximation |
see
stripping
|
| retraction
|
posterior
movement of teeth |
| retroclined
|
a backward
inclination of an incisor tooth, usually determined from a
cephalometric analysis; see inclination |
| retrusive or
recumbent |
a backward
position of an incisor tooth, usually determined from a
cephalometric analysis |
| rotation
|
turning of a
tooth by movement around its long axis; a tooth is said to
be rotated if turning it around its long axis is required in
order to bring it into its proper position |
| separator
|
a device
inserted between teeth which are to be fitted with
orthodontic bands; usually made of elastomeric material or
small metal springs, separators will push the teeth apart so
that the band material passes freely through the contact
area. |
| sheath
|
a fixed
attachment, welded or soldered to a band, which is
specifically designed to receive removable auxiliaries such
as lingual arches, etc. |
| skeletal
malocclusion |
a malocclusion
characterized by deviations from the normal in the size,
shape, or position of craniofacial bones; there may or may
not be a concomitant dentoalveolar malocclusion |
| slot,
bracket |
that portion of
a bracket which receives an arch wire; Edgewise bracket
slots are rectangular in cross section, either 0.018 x 0.025
or 0.022 x 0.028 inches in dimension with the shorter
dimension open to the buccal or labial |
|
source |
the tube
which supplies X-rays in a
cephalometer ; see
target |
| spacing
|
exists
when the sum of the mesiodistal widths of the teeth in an
arch is less than the
arch circumference |
|
stripping |
reduction of
mesiodistal tooth width by removal of interproximal enamel
|
|
subdivision |
an Angle
Class II or Class III
malocclusion that is unilateral; the designation of the
subdivision as 'right' or 'left' indicates the side which is
Class II or Class III |
|
supraocclusion |
eruption of a
tooth or teeth beyond the normal level |
|
target |
the
target anode which is bombarded by a stream of electrons
from a heated cathode in an X-ray tube; is used as one
factor in calculating magnification ratios in
cephalometry
|
| tension zone
|
that part of
the periodontal ligament that is tensed as a result of an
applied orthodontic force |
| tie wing
|
that portion of
a bracket which retains a ligature |
| tipping
|
the tendency of
a tooth to turn or rotate in either the mesio-distal or
bucco-lingual direction when a force is applied to the
crown; thus, tipping can change either the
inclination or angulation of a tooth
|
| tipping,
uncontrolled |
the application
of a force to the crown will cause a tooth to rotate around
a center near the middle of the root; thus, the apex will
move in the opposite direction to the crown as the tooth
tips |
| tipping,
controlled |
the application
of a force plus a moment to the crown which is designed to
cause the tooth to rotate around a center that is at the
apex; thus, the crown moves the greatest distance and the
apex moves the least as the tooth tips |
| torque
|
with respect to
the Edgewise appliance, it is the force system created when
a rectangular arch wire is engaged in a bracket slot in
torsion, and which has the effect of changing the
inclination of the tooth; also refers to torsion bends
(twisting) deliberately placed in a rectangular arch wire
which are intended to change the inclination
of the tooth |
| translation
|
all points on a
tooth move in a parallel straight line; the
center of rotation is at infinity |
| twin bracket
|
an arrangement
in which two Edgewise brackets are attached to the same base
in order to effect better control of individual tooth
rotations; also referred to as a Siamese bracket.
|
|
zygion |
the most
lateral point on the zygomatic arch |
