Transcript ORTHODONTIC REMOVABLE APPLIANCES, THEIR …

REMOVABLE ORTHODONTIC
APPLIANCES (ROA), THEIR
INDICATIONS AND
CONTRAINDICATIONS
by Dr. Wangui .K.
Objectives
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Definition of ROA
Brief History of ROA
Mode of Action
Components of ROA
Indications & Contraindications of ROA
Definition:
Appliances that can be inserted and removed
from the mouth at will, by the patient.
History
• Victor Hugo early 20th century used vulcanite
bases
• Crozat used precious metals i.e. gold for arch
expansion
Action of removable appliances
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Act by tipping the tooth around its centre of
resistance.
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Teeth that have their apex at the correct
position are ideally suited for treatment with
ROA.
• Ineffective in bringing about bodily
translation, derotation and uprighting due
to the single point of contact of these
appliances
• Incorporation of bite planes enables
intrution and extrusion of teeth
COMPONENTS OF ROA
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retentive components
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active components
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base plate
Retentive Components
Clasps:
• Adam’s clasp
• Crozat clasp
• Circumferential clasp
• Jackson’s clasp
• South end clasp
• Ball end clasp
Requirements of clasps
Easy to fabricate & clean
• Shouldn't impinge on soft tissues
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Provide adequate retention
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Deciduous and permanent dentition
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No active forces causing unwanted tooth
movement
Active Components
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Bows
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Springs
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Screws
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elastics
Bows
*Uses & Examples:
• Short & long labial bow
• Reverse labial bow
• Split labial bow
• Roberts retractor-severe overjet
• Mills retractor
• High labial bow with apron springs
Springs
Requirements:
• Easy to fabricate and clean
• Robust
• Should not be easily dislodged
• Force in required magnitude and direction
• Active over a long period of time
• Should fit easily in available space
*Uses & Examples:
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Finger springs
Z spring
T spring
Coffin Spring
Canine retractors
Screws
Used to:
• expand arch
• Buccal lingual & mesio-distal tooth movement
• Activated using a key
Elastics
• Rarely used with ROA.
• used for anterior teeth retraction
Base Plate
dIndications of ROA
Contraindications of ROA
Expansion of narrow arches
Severe skeletal discrepancy
Treatment of Individual arches
Severe rotation
Bite correction
Upper & lower arch correlation
treatment
Unilateral Crossbite
Bodily movement
Single malpositioned teeth
Severe crowding
Bad habits
Very dense bone
References
Orthodontic Art and Science S.I Bhalajhi
• Orthodontic Pearls Eliakim Mizrahi
• Adams: Removable Appliances Yesterday
and Today American Journal of
Orthodontics1969;202-218
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