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

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Removable Appliances
Introduction:-

• Definition:Orthodontic appliance are devices by
means of which mild pressure may be
applied to a tooth or group of teeth & their
supporting structure so as to bring about
necessary changes within the bone which will
allow tooth movement.

Classification:• Broadly classified into two groups
Mechanical
-removable
-fixed
Myofunctional
-removable
-fixed

• Classification of removable
appliances:1)According to Graber & Neumann:a) Active appliances-force within the appliance.
b) Functional appliances-use muscular forces.

2)According to the function of removable
appliances:-


a)For buccal or labial movement:
-Z spring
-T spring
b) For lingual movement:
-Canine & premolar spring
-Molar spring
-Soldered auxillary spring
c) For mesial & distal movement:
-Finger spring
-Expansion screw
-Canine retractors

d) Spring for expansion:
-Coffin spring
-Screw appliance
e)Extrusion & intrusion of teeth:
-Anterior bite plane
-Posterior bite plane
-Inclined plane
f) Habit breaking appliances:
-Tongue spikes,cribs for tongue thrust.
-Lip bumper for lip sucking.
-Oral screen for mouth breathing.

g)According to attachment:i) Attachment at one end- Cantilever spring
ii) Attachment at both end- Labial bow
h)Number of arms in spring:i) Single cantilever- Finger spring
ii) Double cantilever- Z spring
i)According to the coil:i) Spring with coil- U shape canine retractor
ii) Spring without coil- Helical coil canine retractor

j)According to the placement:i)Buccal spring/Labial springHelical canine retractor
ii)Palatal/Lingual springFinger spring, Z spring
k)According to force applied:i)Push type-Labial wire of removable appliance
ii)Pull type- Retraction ligature


l)According to amount of pressure applied:-Heavy pressure
-Light pressure
m)According to mode of adhesion:-Bonding
-Banding
n)Functional/muscle motivating orthodontic
appliance are divided into thre broad
categories[Graber Neumann]
Group I-Teeth supported appliance
eg:Inclined planes,Oral sheilds
Group II-Teeth/tissue supported appliance
eg:Activator , Bionator

Group III- Vestibular positioned appliance
eg: Frankel functional regulator
Oral screens
o) Schwarz recognized the intimate relationship of
force magnitude & tissue response & classified
orthodontic force into four degrees of biological
efficiency [Graber Neumann]
i) First degree of efficiency:
The orthodontic force in the first degree of efficiency
are below the threshold of stimulation needed to
activate orthodontic tooth movement or they are
balanced by compensatory forces.
eg: Frankel appliance

ii) Second degree of efficiency:
are that type of forces that are most favorable to
achieve continuous tooth movement without root
resorption. Resorption of alveolar bone in the
pressure zone will happen at the same rate as
deposition in the area of tension.
iii) Third degree of efficiency:
are that forces that can interrupt the blood
circulation in the periodontal membrane. They
are of medium strength 20-50 gm/cm. The tissue
are not yet crushed.


iv) Fourth degree of efficiency:
are of such magnitude that the periosteal membrane
is crushed between the root & alveolar bone in the
area of greatest pressure. If continuous, the
consequence is extensive necrosis of alveolar bone
& root resorption. Irreparable may be caused to the
tissue involved.


Components:• In removable orthodontic appliancesI. Active components
spring
bows
screws
elastics
II. Passive components
clasp

III. Base plate
• In fixed orthodontic appliancesI. Active components
seprators
archwires
elastics
elastomerics
springs
magnets

II. Passive components
bands
bracket
buccal tubes
lingual attachments
→lingual buttons
→lingual seating lugs
→lingual eyelets
→lingual cleats
→lingual sheaths
→ lingual elastilugs
→lingual ball hooks
→lock pins
→ligatures wires

Ideal requirements
•
•
•
•

Biologic requirements
Mechanical requirements
Esthetic requirements
Hygienic requirements


• Classification of spring:
According to attachment:i) Attachment at one end- Cantilever spring
ii) Attachment at both end- Labial bow
Number of arms in spring:i) Single cantilever- Finger spring
ii) Double cantilever- Z spring
According to the coil:i) Spring with coil- U shape canine retractor
ii) Spring without coil- Helical coil canine retractor

Spring wrapped around heavy wire: eg:
Apron spring.


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

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