orthopaedic appliances

1. Orthopaedic appliances

2. Introduction
In orthodontic practice ,forces employed are basically of two types
-Orthodontic force (that moves the teeth efficiently ):applied using wires
and other active components of fixed and removable or fixed appliances
Force produced by this appliances are light and range from 50-100 grams
-Orthopaedic force (effect the deeper cranio-facial structures):
The orthopedic forces on the other hand are heavy forces of over 400 grams
that bring about a change in the skeletal tissue

3. -Forces applied to the teeth have the potential to radiate outwards and affect
the nearby skeletal structures.
-For such skeletal changes to occur, the forces employed should be over 400
grams.
-Thus the orthopedic appliances utilize the teeth as handles to transmit the
forces to the adjacent skeletal structures.
-In order to produce skeletal changes, consideration should be given to the
AMOUNT OF FORCE APPLIED and the DURATION OF FORCE.
BASIS FOR ORTHOPAEDIC APPLIANCES

4. AMOUNT OF FORCE
Heavy forces of over 400 grams totally compress the periodontal
ligament on the pressure side and cause hyalinization that prevents the
tooth movement.
These heavy forces are conducted to the skeletal structures to produce
an orthopedic effect.
DURATION OF FORCE
Intermittent forces ranges from 12-14 hours a day are believed to
bring about minimum tooth movement but maximum skeletal
change

5. The commonly used orthopedic appliances are
A . HEAD GEAR
B . FACE MASK
C . CHIN CUP

6. HEAD GEAR
Head gears

7. HEAD GEAR
Most commonly used extra oral orthopedic appliance
Used during the growth period to intercept or correct certain skeletal
malocclusions as well as to distalize the maxillary dentition or maxilla
itself.
Also form one of the important adjuncts to control or gain anchorage.
They derive anchorage from the cervical or the cranial regions.
The major 3 components
1. Face bow
2. The force element
3. The head cap or cervical strap

8. FACE BOW
Two types of face bow
1. Inner and outer bow type
2. J hook type
Inner-outer bow type
The face bow is a metallic component that helps in transmitting the
extraoral forces on to the posterior teeth. The face bow consist of :
A . Outer bow
B . Inner bow
C . Junction

9. Outer bow is made up of 1.5mm stiff round wire and is contoured to fit around
the face the outer bow can be short, medium or long
Short –outer bow is lesser in length than inner bow
Medium – outer bow length equal to inner bow
Long – outer bow is longer than inner bow
The distal end of the outer bow is curved to form a hook that gives
attachment to the force element .
Inner bow is made up of 1.25mm round stainless steel wire and contoured
around the dental arch and molars .The inner bow is inserted in to the buccal
tubes fixed on the maxillary first molars. Stops are placed on the inner bow from
sliding too far through the tubes

10. The junction is the rigid joint of inner and outer bow it can be
a. Simple soldered
b. Wrapped soldered or
c. Welded joint
It is placed at the midline of the bows in case of symmetric forces required
it can be shifted from midline when asymmetric forces are needed
Inner bow attached to the
tube on first molar
junction

11. The ‘J’ hook type of face bow
It consist of two 0.072 inch curved wire whose ends form hooks that are contoured
to fit over a small soldered stop on the maxillary arch wire their normal site of
attachment on the arch wire is between the lateral incisor and canine .the j hook type
of face bow is therefore used along with maxillary fixed appliance having a continuous
arch wire they are used for retraction of maxillary anteriors and have limited
orthopaedic indications

12. The force element
It is that part of the assembly which provides the force to bring about desired
effect .this may comprise of Springs, elastics and other stretchable materials. The
force element connects the face bow to the head cap or neck strap

13. The head cap or cervical strap
The appliance takes anchorage from the rigid bones of the skull or from the back of
the neck by means of a Head cap or a neck strap or a combination of the to the
selection of this depends upon the
individual patients needs

14. Principles in the use of headgears
Headgear have the ability to move the dentition and the maxilla in all the
three planes of space .
Factors to be considered when planning the use of headgears include
A . Centre of resistance of the dentition :The inner bow of the face bow
is generally attached to the maxillary first Permanent molars through buccal
tubes on these teeth .Thus the force acting on the molars tends to displace
them. A decision should be made whether bodily movement or tipping
movement of the teeth is required .

15. B . Centre of resistance of maxilla
The centre of resistance of maxilla as whole should also be considered when
planning for headgears .It is believed to exist at the posteriosuperior aspect of
zygomaticomaxillary suture . Under clinical Conditions the centre of resistance
of the dental arch , as a whole should be considered this is located between the
roots of the premolars
Forces passing through the centre of resistance of maxilla produce translation
of the maxilla in a distal direction . While forces passing above or below this point
causes rotation of the maxilla

16. The center of resistance for a molar is usually at the mid-root region.
-Force applied at center of resistance causes bodily movement
-Force applied below center of resistance causes distal crown tipping
-Force applied above center of resistance cause distal root tipping
C . The point of origin of force
Headgears derive anchorage from the occipital region of the cranium or the cervical
region(back of the neck) . Occipital headgears produce a superior and distal force on
the teeth and the maxilla , while cervical headgears inferior and distal force.
Based on this criteria type of anchorage(point of origin) is to be selected

17. D . Point of attachment of force
The point of attachment refers to the hook present on the distal end of the outer
bow to which the force element is attached . It is possible to alter the direction of
force to maxilla and the maxillary dentition by altering the point of attachment .
This can be done by varying
-the length of the outer bow or
-by varying the angle between the inner and outer bow

18. Types of headgears
Based on the site of anchorage headgears can be :
1 . Cervical headgears
2 . Occipital headgears
3 . Combination headgears
4 . Vertical pull headgears
5 . Asymmetrical headgear

19. Cervical headgears
These headgears obtain anchorage from nape of the neck . Cervical headgears
causes extrusion of the maxillary molars leading to an increase in the lower
facial height .They also move the maxillary dentition and the maxilla in a distal
direction .These headgears are generally indicated in low mandibular angle cases ,
as in increase in lower facial height would be beneficial in such patients
consideration
Relation of line of force to the centre of resistance is to be considered as if line
of force is passing below the centre of resistance we can expect a clockwise
rotation of maxilla

20. Cervical pull headgear

21. Occipital headgears
These headgears derive anchorage from the back of the head . This type of
headgear produces a distal and superiorly directed force on the maxillary teeth
and the maxilla . These high pull Headgears produce a more vertically directed
force and there for is used in individuals in whom an increase in vertical dimension
is to be avoided . They decrease the vertical development of maxilla and there
for indicated in long face class 2 patients and in patients with open bite tendencies
Combination headgears
In this type of headgear ,occipital and cervical anchorage is combined . When the
forces exerted by both are equal , a distal and slightly upward force is exerted on
the maxillary dentition and the maxilla . By varying the proportions of the total
force derived from the head cap and the neck strap the resultant force direction
can be altered

22. Occipital headgear Combination headgear

23. Vertical pull headgear
They are headgears that derive anchorage from the
parietal region of the cranium and there for Produce
a vertically directed force on maxilla and the
maxillary dentition these headgears can be used to
produce intrusive forces on the anterior region of
the maxilla and there by producing a Counter-
clockwise movement of maxilla . This is beneficial
in the treatment of vertical maxillary excess and
gummy smiles . Intrusive forces on the posterior
aspect of maxilla can be of benefit in anterior open
bite patients as it intrude the maxillary molars and
therefore produces a clockwise movement of
maxilla

24. Asymmetrical headgears
They are used when differential anchorage is required on both sides of the
maxillary arch. For Example a patient with class 2 molar relation on one
side and a class 1 molar relation on the other side can be given an asymmetric
headgear . The different force values are produced by Altering the length of
outer bow on each side and by variation of the angle between the outer And inner
bows

25. Uses of headgears
A . Orthopaedic effect : Forces applied onto the maxilla can be used to restrict
its downward and forward Growth . The distal force in such a case should be
applied through the centre of resistance of the maxilla . The suggested range
of force is 350-450 gms on each side for a minimum of 12-14 hrs /days are
required Orthopeadic effects from extraoral forces are best tapped in pre
adolescent years
B . Anchorage augmentation : Extra oral forces are used to reinforce
anchorage when those Obtained from intraoral sources are insufficient . The
headgear should be worn for approximately 10 hours/day for this purpose and
force values of 300 gms /side are usually sufficient . In the maxilla anchorage
reinforcement is achieved by restricting the mesial movement of molars

26. C . Distalization of molars : distal movement of upper molar may be
required for correction of molar relation or to gain space for correction of
crowding or retraction of anteriors this can achieved by using it for
14 hrs/ days . Unilateral distalization of molars is achieved using asymmetric
headgear of cervical or combination type (larger force on the side of longer
bow )
D . Molar rotation : in order to derotate a molar the molar has to be
banded with the buccal tube placed distally and then subsequently
repositioned . Correction is achieved by adjustment of the inner bow
so that it produces a rotational force on the molar . As soon as the
correction is achieved ,the Face bow should be readjusted to apply a
direct distal force

27. E . Space maintenance : a most effective method of maintaining arch length
is by the use of extraoral forces the mesial movement of molar is prevented
and the face bow does not interfere with erupting teeth . In this situation
daily wear of approx. 8 hrs is sufficient

28. Face mask

29. Introduction
Headgears are generally used for the purpose of reinforcement of anchorage or for maxillary
Distalization . However, when an anterior protractory force is required , a protraction headgear is
used . Facial mask therapy has gained popularity. The principal of pulling force on the
maxillary structures with reciprocal pushing force on the forehead or mandible through facial
anchorage is simple and mechanically sound enough to be used as a therapeutic procedure for
treatment of prognathic syndromes, maxillary retrusions , clefts and mandibular prognathism
Hickham (1972) claims he was the first to use reverse headgear. However this modality
was made popular by Delaire around the same time .
A reverse pull headgear basically consists of a rigid extraoral framework , which takes
Anchorage from chin or forehead or both for the anterior traction of the maxilla using extraoral
Elastics that generate large amount of force up to 1 kg or more

30. Indications
1 . In a growing patient having a prognathic mandible and a retrusive maxilla . It aids in
pulling the Maxillary structures forward and pushing mandibular structures backward
2 . It can be used for bending the condylar neck for stimulating temporo-mandibular joint
adaptation to posterior displacement of chin
3 . It can also be used for selective rearrangement of the palatal shelves in cleft patients
4 . It can be used in correction of postsurgical relapse osteotomies(or uncontrolled
postsurgical Adaptations )
5 . It can also be used to treat certain accessory problems associated with
nose morphology such as lateral deviations.

31. Sites of anchorage
Anchorage for the purpose of maxillary retraction can be obtained from
A . Forehead
B . Chin
C . Or both chin and forehead
Anchorage from chin :This type of protraction head gear is commonly used
in Britain ,chin cup with posts are employed . As the anchorage is obtained
solely from the chin ,the force is transmitted to the condylar cartilage and thereby
has a disadvantage of altering the growth of the mandible

32. Anchorage from chin & forehead Anchorage from forehead (skull)

33. Anchorage from skull :Certain form of reverse pull head gears obtain anchorage
only from forehead .The disadvantage include patient discomfort while sleeping , cost
and time required in fabrication and fixing
Anchorage from chin & forehead : This face mask makes use of anchorage from
both chin and forehead .Anchorage is spread over a larger area . Thus no excessive
force is exerted onto the growth cartilage . However the disadvantage with this
appliance are difficulty in speech and compromise in esthetics and Comfort due to
size

34. Biomechanical considerations
Amount of force : The amount of force required to bring about skeletal changes
is about 1 pound(or 450gms) per side
Direction of force : Most authors recommend a 15-20 degree downward pull
to the occlusal plane to produce a pure forward translatory motion of the maxilla .
If the line of force is parallel to the Occlusal plane, a forward translation as well
as an upward rotation take place .

35. Duration of force : The time taken to achieve desired result is
proportional to the amount of force utilized . Low forces (250 gm /side)
take 13 months to produce desired results. However ,very high
Force values like 1600-3000gms reduced treatment time to 4 -21 days
Frequency of use : Most authors recommend 12-14 hours of wear a day

36. Parts of a reverse pull headgear
The reverse pull headgear consists of the following parts :
Chin cup: Most protraction headgears obtain anchorage from chin as well as the
forehead . The chin cup is used to take anchorage from the chin area . It is usually
connected to the rest of the face mask assembly by means of metal rods . The chin
cup can the ready-made or can be fabricated from an impression from the patient’s
genial region .
Forehead cap : The forehead support or cap or strap is used to derive anchorage
from the forehead

37. Forehead cap
Chin cup
Metal frame

38. Elastics : Elastic force is used to apply a forward traction on the upper arch .
Vertical posts of chin cup are used to attach the elastics on to the molars or
hooks soldered on the arch wire . This sort of traction is purely for tooth
movement
Intraoral appliance : The most common type of protraction device is a
multibanded appliance with ridge Wire. Traction hooks are placed either in
the molar or premolar region McNamara advocates a banded R.M.E. along
with the protraction device that more or less resembles the banded Herbst
appliance

39. Metal frame : The main component of a face mask assembly is the metal frame .
It connects the various components such as the chin cup and the fore head cap .
It also has provision to receive elastics from the intraoral appliance . The design
of the metal frame differs based on the type of face mask
Metal frame
Elastics
Intraoral appliance

40. Types of reverse pull head gears
Protraction headgears by Hickham: developed in the early 60’s, this appliance
uses the chin and top of the head for anchorage . The force distribution is as
follows – 15% head ,85%chin . It consists of two short arms in front of the
mouth to engage maxillary protraction elastics .It also has a chin cup from which
originate two long arms . The two long arms run parallel to the lower border of
the mandible and go vertically up from the angle of mandible and end behind the
ears . An elastic strap is attached to the end of the long arms to encircle the head
the advantage of the appliance include relatively better esthetics and comfort than
others with the option of unilateral force applicability . By adding a rubber
cushion under one arm , Force to that side can be altered

41. Two short arms
Chin cup
Long arm
The elastic strap
Parts of hickem’s chincup

42. Face mask of Delaire :this was popularized by Delaire in the 60’s and also
uses the chin and Forehead for support . The appliance is made up of a rigid
wire framework which is squarish and kept away from the face . It has a
forehead cap and a chin cup with a wire running in front of the mouth used
for elastic attachment
Tubinger model: this is a modified type of delaire face mask . It consist of a
chin cup from which originates two rods that runs in the midline and is shaped
to avoid the interference of the nose . The superior ends of the two rods
house a forehead cap from which elastics encircle the head .In addition, a
crossbar extends in front of the mouth which can be used to engage the
elastics .The forehead cap and crossbar can be adjusted by sliding along the rod
framework to suit the individual patient.

43. Forehead cap
framework
Wire running in front of mouth
Chin cup
Delaire face mask Tubinger model

44. Petit type of face mask : this is also a modified
type of Delaire face mask. It consist of a chin
Cup and a forehead cap with a single rod
running in the midline from forehead cap to
chin cup . A cross bar at the level of the mouth
is used to engage elastics . The advantage of this
model is that the forehead cap ,chin cup and the
cross bar can be adjusted to suit the patient

45. Chin cup

46. Introduction
The chin cup or thin cap as it is sometimes referred to is an extraoral
orthopaedic device that covers The chin and is connected to a headgear .
It is used to restrict the forward and downward growth of the mandible .
The chin cup – face bow assembly consist of a chin cup that covers the
chin , a head cap and an adjustable elastic strap that connects the chin cup
with the head cap

47. Types of chin cups
Chin cups are of two types . They are the occipital pull chin cup and the vertical
pull chin cup
Occipital pull chin cup: This type of chin cup derives anchorage from the
occipital region of the head . This is the most commonly used type of chin
cup . It is used in class 3 malocclusions associated with mild to moderate
mandibular prognathism .they are very successful in patients who can bring
their incisors close to a edge-to-edge position at centric relation . They are
also indicated in patients with slightly protrusive lower incisors as they
invariably produce lingual tipping of the lower incisors

48. Vertical pull chin cup : this type of chin cup derives anchorage from the parietal
region of the head . It is indicated In patients with steep mandibular plane angle and
excessive anterior facial height . These Patients usually exhibit an anterior open bite
.
Occipital pull chin cup Vertical pull chin cup

49. Fabrication of chin cup
Chin cups are either fabricated individually for the patient or pre-fabricated
commercially available chin cups can be used . The fabrication of chin cup
requires an impression to be taken of the chin area. The cast is poured and the
chin cup fabricated using self-cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used .
Over the next two months the force is gradually increased to 450-700grams
per side . The patient is asked to wear the appliance for 12-14 hours a day to
achieve the desired results

50. Reference
Orthodontics the art and science – S.I. Bhalajhi

51. Thank you