Removable orthodontic appliances 1 /certified fixed orthodontic courses by Indian dental academy

REMOVABLE ORTHODONTIC
APPLIANCES
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


CONTENTS

• BOWS
• ELASTICS

• SCREWS
• BASEPLATE
• SUMMARY & CONCLUSION

BOWS
Bow is that component of removable
appliance which helps in retracting and
retaining the teeth and also contributes
for the retention of the appliance.


USES
•

retraction of anterior teeth.

•

retention of teeth, after active
orthodontic treatment is
completed.

•

attachment of auxiliary springs.

•

for carrying soldered attachments.

TYPES OF BOWS
SHORT LABIAL BOW
Most commonly employed labial bow.
Construction:
Wire used for construction- 0.6mm for
retraction and 0.7mm for retention.
Bow adapts labial surface of the incisors
at about the junction of middle and
incisal thirds of the teeth.

U-loops are formed above gingival
margins and should be short of sulcus to
prevent irritation of soft tissues.
Contraindication

In case of severe proclination of
incisors.
Activation
By closing the U-loops.

Advantages

• fabricated easily
• for retention
• hooks can be soldered
• offset bends can be made for minor
movements of individual teeth.


LONG LABIAL BOW
Construction
Wire used for construction –0.6mm for
retraction and 0.7mm for retention.

Activation- by closing the U-loops
Uses

•

to close space between canine and
premolar.

•

used for retention.

SPLIT LABIAL BOW
0.6mm wire is used for construction
The bow is split to increase the
flexibility of the bow
Suitable for incisor retraction
Adjusted at U-loops


ROBERTS’ RETRACTOR
0.5mm wire inserted into SS
tube/sleeve to give support at the
either end of the bow

A coil is placed at the point of
emergence of the wire from the tubing
Tubing emerges from the base plate
distal to the canine

Flexibility lies in the vertical limbs
Activation- by bending in the vertical
limb below the coil.Once the incisors are
retracted the horizontal arm should be
re adapted.
Advantages
•

used for correction of severe
protrusions

•

light force is applied as thinner wire
is used & has longer range of action.

HIGH LABIAL BOW WITH APRON
SPRING
O.9mm wire extending into buccal sulcus.
The impression must be muscle trimmed
so that the frenae can be avoided.
The apron spring is made of 0.35-0.4mm
wire which is attached to the base of the
arch by wrapping a few turns round the
vertical step.

Care should be taken not to twist the
wire to prevent incorporation of stress

Activation- spring is bent towards the
teeth
Advantages
•

used for correction of severe
protrusions

•

light force is applied as thinner
wire is used & has longer range of
action. www.indiandentalacademy.com

LABIAL BOW WITH SELF
STRAIGHTENING WIRES
Increased flexibility (0.4mm wire)
Used to reduce an over jet

Individual tooth movements cannot be
undertaken
Adjustment is made by closing the Uloops of the bow and self straightening
wires should run freely on the
supporting bow

LABIAL BOW WITH REVERSE
LOOPS
0.7mm wire is used for fabrication.
Should be well clear of clasps on first
molars.
Reverse loops help in preventing the
buccal drift of canines during retraction
of anterior teeth.

ActivationFirst the vertical loop is opened by
compressing the loop, later compensating
bends are placed at the base of the loop

Flexibility can be improved by
incorporating the self straightening
wires or by splitting it.


EXTENDED LABIAL BOW
0.7mm wire is used.
Flexibility is increased because of
enlarged loops.

Useful alternative to Roberts’ retractor
Less comfortable for the patient to wear
due to size of the loops.


FITTED LABAIL BOW
0.7mm wire is used for construction
Similar to short labial bow except that
horizontal part is closely adapted on to
the labial surfaces.
Used for retention


BEGG RETENTION BOW
0.9mm wire is used for fabrication.
Serves the purpose of the both the
active and retentive components.

Avoids the need for a molar clasp by
using a continuous bow with adjustment
loops which emerges distal to the upper
molars.
Allows the settling of the occlusion.

ELASTICS
Used as a convenient means for applying
pressure
Occasionally used as the intra oral active
component of a removable appliance,
usually to retract upper or lower
incisors.

Latex elastics are used for intra oral
use.

Available in various sizes (1/8 inch-5/16
inch) and selected based on the amount
of loading.
Patient is advised to renew the elastics
every few days.
They have the advantage of being
inconspicuous and comfortable but they
tend to ride upon the crown of the tooth
causing gingival damage.

SCREWS
Active component of a removable
appliance.
Used to bring about the expansion of
either dental arches and/or skeletal
bases as required.
Combine strength with limitation of
force within physiological limits when
properly handled.

DESCRIPTION OF A SCREW
Consists of a central oblong body which
is divided into two parts.
Each half is tapped centrally to receive
one end of a double ended screw.
Holes are drilled transversely through
the centre boss of the screw for the
insertion of a key.

There are four of these holes, so that
screw is turned ¼ revolution at each
adjustment.

One end of the screw has a left hand
thread thus turning of the screw
withdraws it from both sides
simultaneously.
Near the side of each half is a guiding
pin parallel to the central screw.

Each guide pin is received into a hole
drilled on the opposing half.
The surface of the body is suitably
serrated to obtain fixation in the plastic
base material.


PITCH OF THE SCREW
The distance moved by the screw on
being turned.
To avoid damage to the attachment of
the tooth the pitch of the screw is
limited.
The width of the periodontal membrane
is 0.15-0.25mm. screw is designed to
open this amount of thickness on each
adjustment(I.e,1/4 turn).

Removable appliances incorporating
screws are divided into 3 types:

A)Expansion appliance with screw
incorporating reciprocal anchorage.
B) Appliance with screw to move
individual teeth or small groups of
teeth in a buccal or a labial direction.
C) Appliance with screw to move
individual or small groups of teeth in a
distal or mesial direction.

EXPANSION APPLIANCE WITH
SCREW
Used to increase the width of dental
arch providing the narrowness is due to
palatal or lingual inclination of the
bicuspids and molars.
Simplest form of this appliance is made
of 2 modified arrow head clasps and a
plastic base divided in the middle, two
halves being united by a screw.

In the upper arch the screw is placed in
the mid-line with its axis set
transversely.
In the lower arch, the screw is placed in
the mid-line lingual to the alveolar
process of the incisor teeth.
The expansion plate is sometimes used
when there is a cross bite, in such cases
it is necessary to disengage the upper
and lower teeth.

APPLIANCE WITH SCREW TO MOVE
INDIVIDUAL TEETH OR SMALL GROUP
OF TEETH BUCCALLY OR LABIALLY
The narrow ness of upper arch is not
always symmetrical, the lingual inclination
may be confined to teeth on one side
only.


Appliance with screw to move one or two
molars buccally:


Appliance with screw to move premolars
buccally:


Appliance with screw to move upper
incisors labially:


APPLIANCE WITH SCREW TO MOVE
INDIVIDUAL TEETH OR SMALL
GROUP OF TEETH IN A DISTAL OR
MESIAL DIRECTION
The anchorage should be reinforced by
means of an inclined plane and a labial
bow.
Only one side of the arch should receive
treatment at any one time

The axis of the screw should be parallel
to the occlusal plane.
Where premolar or molar are to be
moved distally the screw should be
placed mesially to the tooth to be
moved.


BASE PLATE:
Constitutes the body of the removable
appliance.
Provides

A)Foundation which supports other
components.
B) Contributes to anchorage.
C) May be built into a bite plane to
disengage occlusion or reduce overbite.

Baseplate act as supports for pressure
sources and distribute the reaction of
these forces to the anchorage areas.
DESIGN AND CONSTRUCTION

The baseplate needs to be thick enough.
Ideally, this should be about as thick as
a sheet of modelling wax.
Should cover most of hard palate,
finishing just distal to the first molars.

The baseplate should fit closely around
the necks of teeth that are not being
moved– otherwise food packing and
gingival hyperplasia may occur.
Baseplates are generally manufactured
from cold-cured acrylic.


BITE PLANES
Acrylic of the base plate may be
thickened anteriorly or posteriorly to
form the bite plane.
ANTERIOR BITE PLANE:
Mainly used for reduction of over bite.

This is mostly successful in in an
actively growing patient.

When designing the anterior bite plane
the over jet and the desired height of
the bite plane relative to the palate and
the palatal surface of the upper incisors
should be taken into consideration.

Bite planes should be made with the
occlusal surface parallel to occlusal plane.
The initial bite plane in adults should be
very thin.

POSTERIOR BITE PLANE:
Used to eliminate lateral or anterior
displacement of the mandible.
Will also assist in the correction of buccal
or an anterior cross bite.
Should be thinner posteriorly than
anteriorly.

Should contact the opposing teeth on
both sides of the mouth.

Difficult to construct accurately unless
the models have been set up on an
articulator.


SUMMARY AND CONCLUSION:
Removable appliances, by definition, are
those that can be inserted and removed
by the patient.
These appliances generally use acrylic
base plates and SS wires.
Can be used in combination with fixed
appliances.

They are used universally as retention
appliances.
Also serve as anchorage.

Used to correct minor tooth movements.


Removable appliances have
ACTIVE COMPONENT

PASSIVE COMPONENT
BASE PLATE


CONCLUSION:
Although there are many treatment
modalities like the use of fixed and
functional appliances which have
restricted the use of removable
appliances, they still are an essential
part of any orthodontic treatment
either during or after the active
treatment.

BIBILOGRAPHY:
THE DESIGN CONSTRUCTION AND USE OF
REMOVABLE ORTHODONTIC APPLIANCES–
C.PHILIP ADAMS & W. JOHN S. KERR
K.G.ISAACSON, J.D.MUIR & R.T.REED

CONTEMPORARY ORTHODONTICS– WILLIAM
R.PROFITT with HENRY W. FIELDS, Jr.
T.M.GRABER & B.NEUMANN
ORTHODONTICS FOR DENTAL STUDENTS–
T.C.WHITE, J.H.GARDINER & B.C.LEIGHTON

ORTHODONTIC PRINCIPLES AND PRACTICE—
T.M.GRABER

ORTHODONTIC CONCEPT FOR GENERAL
PRACTICE– SPIRO.J.CHACONAS

TEXTBOOK OF ORTHODONTICS–
TULLEY & HOUSTON


THANK YOU


Removable orthodontic appliances 1 /certified fixed orthodontic courses by Indian dental academy

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