Components of removable appliances 2 /certified fixed orthodontic courses by Indian dental academy

Removable orthodontic
appliances
• Active components
* Springs
i) Finger spring:-most important
removable orthodontic
appliances.
-used for mesiodistal
movement of the teeth.

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ii) Z spring:It is used for labial
movement of incisors
& correction of minor
rotations.

iii) T spring:It is used for the
buccal movements of
the premolars &
canine.

iv) Mattress spring:used for the correction
of labial movement of
the teeth in crossbite
where sufficient
space available for
tooth movement.
v) Helical coil spring:used to regain lost
extraction space.


vi) Coffin spring:Introduced by
WALTER COFFIN in
1881.
It is an omega
shaped spring which
helps to bring about
arch expansion.


vii) Canine retractors:#Buccal self supported
canine –
→ It is made up of 0.7mm
wire. It consists of
active arm, helix of
3mm diameter & a
retentive arm. Coil is
placed distal to long
axis of canine.
→ indicated in case
where canine is
buccally place &
placed high in
vestibule.

#Palatal canine
retractor:→Made up of 0.6mm
stainless steel wire. It
consists of active arm,
helix coil,& a guiding
arm.
→It is indicated in case of
palatally placed canine
which required
retraction.


#Helical canine retractor:→Also called reverse loop
canine retractor. Made up
of 0.6mm wire.
→It consist of active arm,
retentive arm & coil of
3mm of diameter.
→Activation done either by
opening the coil by 2mm
or by cutting 2mm of free
end & readapt it around
the canine.

# U loop canine retractor:→Made up of 0.6-0.7mm
round stainless steel
wire.It consists of U loop,
active arm & retentive
arm.
→U loop placed 2-3mm
below the cervical margin.
→It is used when minimum
retraction (12mm)required.
→ It is easy in fabrication &
less bulky.

• Bows:i)Short labial bow:→Made up of 0.7mm
round stainless steel
wire.It is constructed in
such a way that the bow
contacts the most
prominent labial
surfaces of anterior
teeth.
→It is used for retention
purpose as well as
minor overjet reduction
& anterior space
closure.

ii) Long labial bow:→It is just the modification of
short labial bow. It extends
from first premolar to first
premolar of opposite side.

iii)Split labial bow :→Modification of short
labial bow. It is split in
the middle.Effective in
anterior retraction &
closure of midline
diastema.

iv)Robert’s retractor:Made up of 0.5mm wire.It
extends from labial
surface of canine to
canine instead of a
regular loop it
incorporates a 3mm
internal diameter helix at
the base of the loop.The
distal arm of the loops are
supported in softened
stainless steel tubes of
0.5mm internal diameter.


v) Reverse labial bow
It’s the modification of
conventional bow. In this
there is a U loop &
activation of the applianceis
done by opening the loop.
vi) Mills retractor:It’s also modification of
conventional bow.It is used
in patients with increased
overjet.But due to it’s
complex design & poor
patient complience it is not
widely used.

vii)High labial bow with
apron spring:It extends high in the vestibule. It
is made up of thicker gauge
wire & onto which thinner
gauge of wire of 0.4mm wire is
attached for the retraction of
one or more upper anterior
teeth.

viii) Fitted labial bow:It adapts the contours of the
labial surface of the teeth
& used for retention
purpose.


• Screw:It’s active component of the
removal appliance.It is
activated by the patient by
using a key.Mainly it can
bring about three types of
movements-Expansion of arch.
-Movement of teeth or group
of teeth in buccal or labial
direction.
- Movement of teeth or group
of teeth in mesial or distal
direction.


• Advantage of screw over the spring:1) Easier to manage.
2) Less chair side time required.
3) Fewer tendencies to get dislodged
ideal tooth movement is achieved by
turning the screw a quarter turn every 37 days.

• Elastics:-seldom used .
-generally used for
anterior retraction
with labial bow.
-Advantage
:Aesthetically
acceptable.
-Disadvantage
: can cause gingival
trauma.
:risk of arch form getting
flattened.

• Passive components
Clasp:
It is a retentive component of the
removable appliance which helps in
keeping the appliance in place & resist the
displacement of the appliance.
Mode of action:
Clasps acts by engaging certain
constricted areas of the teeth that are
called undercuts

• Two types of undercuts are found in
natural dentition
1)Buccal & lingual undercuts“C”clasp & Jackson’s clasp.
2)Mesial & distal undercutsAdam’s clasp & Crozat clasp.

• Requirement of the clasp
1)Should offer adequate retention.
2)Can use in partially & fully erupted teeth.
3)Easy to fabricate.
4)Should not apply active force.
5)Should not impinge soft tissue.
6)Should not interfere with normal occlusion.

1) Circumferential clasp:
→also called Three quarter or C
clasp.
→Parts :-Circumferential
retentive tip, interocclusal
arm, retentive arm.
→Advantages:
i)Easy to fabricate.
ii)Simple in design.
→Disadvantage:
Can not used in partially
erupted teeth.

2)Jackson’s clasp:
→Also called U clasp or Full
clasp.
→Advantage:
-Easy to construct.
-Offer adequate retention.
→Disadvantage:
-Inadequate retention in
partially erupted teeth.


3) Adams clasp:-By C.P.Adams.
-Also called as Liverpool
clasp,Universal
clasp,Modified arrowhead
clasp.
-Parts…Two
arrowheads,Bridge,Two
retentive arms.
Advantagesi)Rigid & offer good retention.
ii)Can used in partially erupted
teeth.
iii)Can give in permanent &
deciduous teeth.

• Modifications of Adams clasp:-


4)South end clasp-Used for retention purpose in
anterior region.
-The wire adapted on the cervical
margin of both central incisors.
5)Triangular clasp-Small triangular shaped clasp
between two adjacent posterior
teeth & engages the proximal
undercut.
-Use: whenever additional
retention needed.

6)Ball end claspThis appliance have a ball
like structure on one
end.This ball can be made
with the help of silver
solder. The ball engages
the proximal undercut
between two adjacent
posterior teeth.
Indication:
Whenever additional
retention is needed.

7)Crozat clasp-Resembles full clasp but an
additional piece of wire
soldered which engages in
mesial & distal proximal
undercut.

8)Schwartz clasp-Also called arrowhead clasp.
-Engages in interproximal area
between premolar & molar.
-Provide adequate retention.


• Disadvantage of
Schwartz clasp:1)Need special arrowhead
forming plier.
2)Occupies large amount of
space in buccal vestibule.
3)Can injure inter dental soft
tissue.
4)Difficult to fabricate & time
consuming.


• Base plate:-It is made up of cold cure acrylic resin.
-The primary function of base plate is to
incorporate all the components together as a
functional unit.
-Helps in anchoring the appliance in place.
-Provide support to wire components.
-Helps in distributing forces over a larger area.
-It’s thickness should be 1.5-2 mm


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Components of removable appliances 2 /certified fixed orthodontic courses by Indian dental academy

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