orthopedic appliance used in orthodontics

1. ORTHOPEDIC
APPLIANCES

2. INTRODUCTION
There are essentially 3 alternatives for treating
any skeletal malocclusion –
1. Growth Modification
2. Dental Camouflage
3. Orthognathic Surgery
Growth modification should be opted wherever
applicable because this precludes the need for
both tooth extraction and surgery.

3.  There are 3 types of orthodontic appliances that can
be used for modifying the growth of
maxilla/mandible-
Orthopedic
Appliances
Functional
Appliances
Inter Arch
Elastic Traction

4. ORTHODONTIC FORCE VS
ORTHOPEDIC FORCE
 when applied brings
about dental
change.
 They are light
forces
( 50- 100 gm)
bringing about tooth
movement.
 when applied brings
about the skeletal
changes.
 They are heavy
forces ( 300-
500gm) that bring
about changes in the
magnitude &
direction of bone
growth.
ORTHODONTIC FORCES ORTHOPEDIC FORCES

5.  The appliances that produce skeletal changes by
applying orthopedic forces are known as orthopedic
appliances. Since they employ heavy forces,
adequate anchorage required is gained by extra
oral means using occipital, parietal, frontal cranial
bones and cervical vertebrae.
 The most widely used orthopedic appliances are-
1. Headgear
2. Protraction Face Mask (reverse pull headgear)
3. Chin Cup

6. BASIS OF ORTHOPEDIC
APPLIANCE THERAPY
 Orthopedic appliances generally use teeth as
“handles” to transmit forces to the underlying
skeletal structures. Basis of orthopedic appliance
therapy resides in :-
1. Amount of force
2. Duration of force

7. Force
High Intermitent
Directed to basal
bone via tooth
Modify the pattren of bone
apposition at periosteal
sutures & growth sites
Duration
10 to 12 hrs
Skeletal changes
rather than tooth
movement

8. PRINCIPLES OF USING
ORTHOPEDIC APPLIANCES
Following are the basic principles of using
orthopedic appliances effectively :-
1. Magnitude of force
2. Duration of force
3. Direction of force
4. Age of the patient
5. Timing of force application

9. Magnitude of force
Extra oral force
400- 600 gm
per side
Maximize
skeletal
changes &
Minimizes
dental changes
Compress the
pdl on
pressure side

10. Duration of force
12 – 14 hrs per
day
Effective bring
about
orthopedic
change
Less damaging
as compared
to continuous
heavy force

11. Direction of force
when the line of force
passes through the center
of resistance of the skeletal
structures to be moved.
Should be decided as per
the clinical need

12. Age of the patient
During mixed dentition
Prepubertal growth spurt
Continued Till Adolescent Growth Spurt
To Prevent Reversal Because Of Residual
Growth Spurt

13. Timming of force application
Evening & nights
Growth harmone
release ↑ during
night
Endocrine
harmones helps in
growth ↑ release
during night

14. Orthopedic
Appliances
Head gear
Face mask or reverse pull
head gear
Chin cup

15. Head gear

16. Introduction
 Headgears are the most widely used extra oral
orthopedic appliances.
1. During growth period to intercept or correct
skeletal malocclusion.
2. To distalize the maxillary dentition or maxilla
3. As an anchorage unit

17. Components of headgear
• Face bow
• J hooks
Force
delivery
unit
• Head cap
• Neck strap
Anchorage
unit
Force
generating
unit

18. Face bow
 It is a metallic framework
made of large gauge wire.
 It can be attached to teeth
either via brackets ( fixed
orthodontic appliance ) or
removable appliance.
 Parts of face bow
i- junction
ii- inner bow
iii- outer bow

19. Junction
It is the point of attachment of the inner and outer bow,
which may be soldered or welded. The junction is
situated in the midline of the bows, although it can be
shifted either right or left side depending upon
asymmetrical force need.

20. Inner bow
It is made up of 0.045” or 0.052” round stainless steel
wire and is countered to follow the shape of dental
arch.
Friction stops are placed in the bow mesial to the
buccal tube of first permanent molar to prevent the
inner bow from sliding too far distally through the

21. Outer bow/ Whisker bow
It is made of a round stainless steel wire of 0.051” or 0.062” that is contoured
to fit around the face. The length of the outer bow can be adjusted to
produce the desired force vector/ line of force.
Outer bow on both sides at the distal end is curved to form a hook that gives
attachment to the force generating unit.
The outer bow can be short, medium or long.
Short – outer bow is lesser in length than inner bow.
Medium – outer bow length is equal to inner bow.
Long – outer bow is longer than inner bow.

22. J’ Hook
This type of face bow consists of two 0.072” curved wires
whose ends form hooks that are contoured to fit over a small
soldered stop on anterior segment of the maxillary arch
wire. Their normal site of attachment on the arch wire is
between the lateral incisors and the canine.
The J hook type of face bow is therefore used along maxillary
fixed appliance having a continuous arch wire. They are
used for retraction of maxillary anteriors and have limited
orthopedic indications.

23. Force generating unit
May be in the form of:-
i) springs
ii) elastics
iii) other stretchable material
Force generating unit Springs are preferred as
they provide a constant force whereas elastics
tend to undergo force decay.

24. Anchor unit
Headgear appliance derives anchorage from extra
oral sites using the rigid bones of skull or back of
the neck. Two basic types of extra oral
attachments that provide anchorage for headgear
are :
1. cervical attachment / neck strap
2. occipital attachment / head cap
A combination of cervical & occipital attachments
may also be used to distribute the external forces
over a wide surface area.

25. Principles in the use of headgear
The following factors should be considered
when planning the use of headgears :
1) Centre of resistance of the dentition :- The
inner bow is generally attached to the
maxillary first permanent molars through
buccal tubes on these teeth. Force acting on
the molars tends to displace them. A decision
should be made as to whether bodily
movement or tipping of the teeth is required.

26.  The centre of resistance for a molar is usually
at the mid root region.

27. Line of forces
passing through the
centre of resistance
of the molars results
in their bodily
movement.

28. Line of force passing
passing above the
centre of resistance
of molar causes
causes distal root
tipping.

29. Line of force passing
below the centre of
resisitance of molar
causes distal Crown
tipping.

30. Centre of resistance of maxilla
Centre of maxilla is
believed to exist at the
posterosuperior aspect
of zygomaticomaxillary
suture.

31. Forces passing through the centre of
resistance of the maxilla produce translation of
maxilla in a distal direction
Forces passing above or below this point
cause rotation of the maxilla.

32. Line of force vector to center of resistance when
occipital head gears are used
 The line of force
pases below both
the center of
resistance of maxilla
and dentition .
 Produces clockwise
rotation of both the
maxilla and the
dentition .

33.  The line of force
passes below the
center of resistance
of maxilla & above
the center of
resistance of
dentition .
 Produces clockwise
rotation of maxilla &
anticlockwise
rotation of dentition .

34. Line of force vector to center of resistance
when cervical head gears are used
 The line of force
pases below both
the center of
resistance of maxilla
and dentition .
 Produces clockwise
rotation of both the
maxilla and the
dentition .

35.  The line of force
passes below the
center of resistance
of maxilla & above
the center of
resistance of
dentition .
 Produces clockwise
rotation of maxilla &
anticlockwise
rotation of dentition .

36. Types of head gear

37. Cervical headgear
 Nape of the neck
 Extrusion of molars leading to an increase in
the lower facial height .
 Move maxillary dentition and maxilla in distal
direction .

38. Occipital head gears
 Back of the neck
 Distal and superiorly directed force

39. Combination headgears
 Upward force is exerted on maxilla and
maxillary dentition .

40. Uses of head gears
Orthopedic effect
Anchorage
augmentation
Distalization
Molar rotation
Space
maintainance

41. Face Mask
Reverse pull head gear

42.  Hickman 1972 was the first to use reverse
headgear
 Modality was made popular by Delaire .
 It basically consist of a rigid frame work , which
take anchor from chin or forehead or both for
anterior traction of maxilla

43. Indication
Growing pateint with retrognathic maxilla &
prognathic mandible
Bending the condylar neck for stimulating tempero
mandibular joint adaptation
Selective rearrangement of the palatal shelves in
cleft pateint
Post surgical relapse after osteotomies
Treat certain accessory problems associated with
nose morphology

44. Site of anchorage
1. Anchorage from chin :- Used in Britain .
Chin cup with post are employed . Anchorage is obtained solely
from the chin the force is transmitted to condylar cartillage .
Disadvantage alters the growth .
2. Anchorage from skull :- Anchorage from
forehead only . Disadvantage include pateint discomfort,
cost and time .
3. Anchorage from chin and
forehead :- Combination of both .

45. Biomechanical consideration
Direction of
force
Duration of
force
Frequencey
of use
• 15 – 20degree downward pull to
occlusal plane – pure forward
translation of maxilla
• Line of force parallel to occlusal
plane forward translation + upward
rotation .
• Low force :- 250 gm / side takes 13
months
• Heavy force :- 1600- 3000gm
reduces time to 4 – 21 days
• 12 – 14 hrs / day wear

46. Parts of reverse pull head gear
1. Chin cup
2. Forehead cap
3. Elastics
4. Metal frame
5. Intraoral appliance

47. Types of reverse pull head gear
• Protraction head gear by Hickham
• Delaire face mask
• Tubinger method
• Petit face mask

48. Hickham protraction head gear
 In 60’s
 Uses chin & head .
 Force distribution
15% head & 85%
chin .
 Two short arm front
of the mouth .
 Two long arm
parallel to the lower
border of the
mandible .

49. Delaire face mask
 In 60’s
 Both chin and head
support
 Square shaped
metal frame work

50. Tubinger model
 Modification of
Delaire

51. Petit face mask
 Modified form of
Delaire
 Chincup and
forehead cap with a
single rod running in
the midline
 A cross bar at the
level of mouth

52. Chin cup

53. Introduction
 Reffered to extra oral orthopedic device to
control the downward and forward growth of
the mandible.
 Consist of chin cup a head cap and an
adujustable elastic strap

54. Types of chin cups
• Derives anchorage from occipital region
• Commonly used
• Class III with mild to moderate
mandibullar prognthism
• Successful in pt who can bring there
incisors close to an edge to edge in
centric occlusion
• Slight protrusive incisors
Occipital
pull
• Derives anchorage from parietal region
• Steep mandibular plane angle and
excesssive lower facial height
• Pateint with anterior open bite
Vertical
pull

55. Force magnitude and duration of wear
 At the time of appliance delivery a force of 150 –
300 gm / side is used
 Over the next two months force is gradually
increased to 450 – 700 gm /side
 Pateint is asked to wear the appliance 12 – 14 hrs
/day .

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