Orthopedic appliances used in orthodontics

1. WELLCOME

2. ORTHOPEDIC APLIENCES
•'orthopedic therapy' is aimed at the
correction of skeletal imbalance with
thecorrection of any dentoalveolar
malocclusion being of less
importance, in which little or no
tooth movement is desired.
Therefore, orthopedic forces are
heavier (= 400 gm) when compared
to orthodontic forces (50-100 gm).

3. THE PHILOSOPHY OF EXTRAORAL
FORCE
• a. Growth modification
• b. Camouflage treatment
• c. Surgical correction
• Growth modification is, by far, the best option
if possible. Growth modification helps in
altering the expression, direction and
magnitude of growth, thus bringing about
favorable jaw growth.

4. BASIS FOR ORTHOPEDIC APPLIANCES
• Amount of Force
• The force magnitude should be h.igh i.e, at least greater than
400 gm (400-600 gm) per side to a maximum total of 2-3 Ib
to make sure that only skeletal and no dental movement
takes place.
• Duration of Force
• According to most authors, intermittent forces produce
skeletal change whereas continuous forces produce dental
movement. Extraoral appliances should be worn
for about 12-14 hours/day to bring about the desired effect.

5. Direction of Force
• The direction of force application should be such as to
maximize the skeletaleffect. A favorable skeletal affect is seen
when a force is directed posterioriy and superiorly through
the center of resistance of the maxilla. The extra oral anchor
unit can be cervical oroccipital to produce a low or high force
vector. The length of the outer bow can also be altered to
change the force vector. A cervical headgear produces
extrusion of the molars along with distalization, whereas an
occipital attachment produces intrusion, which is favorable in
Class IIcorrection.
• Age of the Patient
• Orthopedic appliances are most effective during the mixed
dentition period as it takes advantage of the prepubertal
growth spurt. effect.

6. • Timing of Force Application
• There is evidence that there is an increase in
the release of growth hormones more during
the evening and night and is associated with
the sleep onset. Therefore, it is advisable for
the child to wear the headgear in the evening
and throughout the night. Generally the child
is more likely to wear the appliance at night.

7. ORTHOPEDIC APPLIANCES
• 1. Headgear
• 2. Facemask
• 3. Chin cup

8. HEADGEAR
• Headgears are the most common among all the orthopedic
appliances. They are ideally indicated in patients with
excessive horizontal growth of the maxilla with or without
vertical changes along with some protrusion of the maxillary
teeth, reasonably good mandibular dental and skeletal
morphology.
• They are most effective in the pre-pubertal period.
• Headgears can also be used to distalize the maxillary dentition
along with the maxilla. They are an important adjunct to gain
or maintain anchorage.
• Components
• 1. Force delivering unit-face bow, J hook.
• 2. Force generating unit.
• 3. Anchor unit-head cap, neck strap

10. Face Bow
• One of the most important components, which help in
delivering extraoral force to the posterior teeth. The
face bow consists of the following.
• Outer BowlWhisker Bow
• It is made up of round stainless steel wire 0.051" or
0.062" in dimension and is contoured around the face.
• The outer bow may be:
• 1. Short-outer bow is shorter than inner bow
• 2. Medium-outer bow is the same length as the inner
bow .
• 3. Long-outer bow is longer than inner bow

11. Inner Bow
• It is made up of 0.045" or 0.052" round stainless steel wire
and inserts into the round buccal tube on the maxillary first
molars. The inner bow is adapted according to the shape of
the arch. 'stops' in the form of 'U' loop, bayonet bends and
friction stops are placed in the bow mesial to the buccal
tube to prevent it from sliding too far distally through the
tube.
• Junction
• It is the point of attachment of the inner and outer bow,
which may be soldered or welded. It is usually positioned at
the midline of the two bows, however, it may be shifted to
one side in case of asymmetric face bows.

12. • Force Generating Unit
• This connects the face bow to the anchor unit and
delivers the force to the teeth and the underlying
skeletal structures. The force element may be springs
or elastics. Springs are preferred as they provide a
constant force whereas elastics undergo force decay.
• Anchor Unit
• This is in the form of a head cap or a neck strap, which
makes use of anchorage from the skull or back of the
neck respectively. A combination of the two may also
be used.

13. Type
• Headgears
• They can be divided as follows
• i. According to direction of force:
• • Distal force
• • MesiaI force
• ii. According to location of anchor unit:
• • Cervical pull
• • Occipital pull
• • High pull (Parietal)
• • Combination pull

15. Cervical Headgear
• The anchor unit in this headgear is the nape of the neck. It causes
extrusion and distalization of the molars along with distal movement of
the maxilla.
• Indications
• 1. Short face, Class IImaxillary protrusive cases with a low mandibular
plane angle and deep bite (true).
• 2. Anchorage conservation. The forward movement can be resisted better
if the anchor molars are supported further using the forces generated by
the cervical headgear.
• 3. Early treatment of Class II malocclusion as it helps to distalize the
maxilla and correct Class II molar relationship.
• Contraindications
• 1. Open bite cases
• 2. High mandibular plane angle
• 3. Long face cases with an increase in lower anterior face height.

16. Biomechanics of Headgear
• An understanding of the biomechanics helps the clinician to
determine the force systems that need to be applied to
produce the desired clinical effects. The line of action of force
is the direction in which the force acts. The relationship of the
line of force action to the center of resistance of the maxilla or
first molar determines whether translation or rotation takes
place.
• When a force does not pass through the center of resistance
of the maxilla/molar, a moment is produced.
• The magnitude of the moment is determined by the product
of the force magnitude and the perpendicular distance from
the line of force to the center of resistance.
• The direction of the line of force can be changed by adjusting
the length of the center bow or by bending the outer bow up
and down to produce the desired clinical effect.

17. Treatment Effects
• Skeletal Effect
• The maxillary sutures namely the frontomaxillary, zygomaticotemporal,
zygomaticomaxillary and pterygopalatine sutures are the most
important growth sites for development of maxilla. Therefore, to alter
the maxillary growth, the headgears act by compressing the sutures
thus restricting the normal downward and forward growth of the
maxilla, while at the same time the mandible is allowed to grow
normally.
• Dental Effect
• Headgear being a tooth-borne appliance, produces certain dental
effects along with a skeletal change. Headgears usually cause
distalization of the maxillary molars. Along with this, extrusion or
intrusion of the molar may also be seen if the extraoral attachment is
cervical or Occipital respectively. In most skeletal ClassII problems a
cervical headgear is not desired as the extrusion of the maxillary molar
caused by the infenorly directed force which causes downward and
backward mandibular rotation, thus worsening the problem.

18. Uses of Headgears
1. To restrain the forward and downward growth of the
maxilla and redirectioning maxillary growth.
2. Molar distalization: Headgear may be used to distalize the
maxillary molar to correct the ClassII molar relationship or
to gain space for relief of crowding.
3. Headgears can be used to reinforce molar anchorage in
high anchorage cases. Headgears should be worn for at
least 10 hr / day with a minimum force of 300 gm per
side.
4. Headgear is an effective means of maintaining arch length
by preventing mesial migration of molars.
5. Molar rotation can also be brought about with the
inner bow of the headgear.

19. FACEMASK
• Class III malocclusion is usually a result of a combination of maxillary
deficiency and mandibular excess. Growth modification for Class III
problems is the
• reverse of Class Il, i.e. treatment involves restriction of mandibular
growth along with downward and forward maxillary growth. When
headgear applies a distal force to the maxilla, compression of the maxillary
sutures can inhibit forward maxillary growth. Likewise, pulling the maxilla
forward and separating the sutures should stimulate forward growth of
the maxilla. Headgears which cause a forward pull on the maxilla are,
therefore, called reverse pull headgear. Facemask.
• A facemask works on the principle of pulling the maxillary structures
forward with the help of anchorage from the chin or forehead or usually
both. A forward maxillary pull is applied with the help of heavy elastics
that are attached to hooks on the rigid framework.

20. Indications
1. Mild to moderate ClassIII skeletal malocclusion due
to maxillary retrusion, reverse pull headgear works
best in young, growing children (around 8 years).
2. Ideal patients for facemask should have:
• Normal or retrusive but not protrusive maxillary teeth
as facemask causes forward movement of the
maxillary teeth relative to the maxilla.
• Short or normal, but not long, anterior vertical facial
dimensions, i.e. a hypodivergent growth pattern.
3. Correction of postsurgical relapse after osteotomies.
4. Selective rearrangement of palatal shelves in cleft
patients

21. Parts of a Facemask
Usually, a facemask is made up of the
following
components:
1. Meta I framework
2. Chin cup/pad
3. Forehead cap
4. lntra-oral appliance
5. Heavy elastics

22. Biomechanical Considerations
• The maxilla can be advanced 2-4 mm forward over a period of 8-12
months. The amount of maxillary movement is influenced by a
number of factors like:
a. Amount of force Successful maxillary protraction can be brought
about by 300-500 gm of force per side in the primary or mixed
dentition.
• b. Direction of force According to most authors, a 15- 20°
downward pull to the occlusal plane is required to produce forward
maxillary movement. In most cases of maxillary deficiency, maxilla
is deficient in the vertical plane as well, therefore, a slight
downward, direction of force is usually desirable. The line of force
passes below the center of resistance of the maxilla producing a
counter-clockwise moment on the maxilla and dentition. This
results in a possible extrusion of maxillary posterior teeth leading to
a downward and backward rotation of the mandible.
• However, in patients with increased anterior facial height,
downward pull is contradicted.

23. c. Duration of force A review of literature shows duration to vary
between 3 and 16 months. On an average at least 8-12 months of
wear is required to produce the desired effect.
d. Frequency of use 12-14 hrs/day.
• Age of patient Optimal results are seen when facemask is used in
the primary or early mixed dentition period. An optimal time to
intervene an early Class lII malocclusion is at the time of eruption
of permanent maxillary central incisors. The anchor molars are also
erupted by this time.
f. Anchorage systems Palatal arches or palatal expansion appliances
may be used as anchorage for maxillary protraction. Various
authors recommend palatal expansion before protraction as
expansion is supposed to "disarticulate" the maxilla making it
favorable to respond to protraction forces.

25. CHIN CUP
• It is an extr-aoral orthopedic device, which is
useful in the treatment of Class III
malocclusions that occurs due to a protrusive
mandible but a relatively normal maxilla.
• Chin cup therapy attempts to retard or
redirect the growth of the mandible in order
to obtain a better antero-posterior relation
between the two jaws.

26. Philosophy of Chin Cup Therapy
• Mandible grows by apposition of bone at the
condyle and along its free posterior border.
Condyle is not a growth center and condylar
growth is largely a response to translation of
surrounding tissues.
• This contemporary view offers a more
optimistic view of the possibilities for growth
restraint of the mandible, as with chin cup
therapy.

27. Line of Direction of Force
• There are two ways to use the chin cup:
• 1. Line of force acting directly through the condyle with the intent
of impeding mandibular growth in the same way that extraoral
force against the maxilla impedes its growth. This method causes
no opening of the mandibular plane angle.
• 2. Line of force acting below the condyle :
• Chin is rotated downward and backward
• Less force is required
• Increase in facial height is achieved for a decrease in the
prominence of the chin.
• 3. Vertical force on the chin:
• Decrease in mandibular plane angle
• Decrease in gonial angle
• Increase in posterior facial height.

28. • Magnitude of Force
• Most authors recommend a force of 300-600
gm/side.
• Initially a lower force level (about 150 gm)
may be advised for the patient to get used to
the appliance.
• Duration of Wear
• A maximum of 12-14 hr/day of chin cup wear
is recommended.

29. Effects of Chin cup
Extraoral force of the chin cup, directed against the mandibular
growth. However, most human studies have failed to conclusively
prove that chin cup inhabits mandibular growth. However, the
following effects are seen.
• a. Redirection of mandibular growth in a downward and backward
direction.
• b. Remodeling of the mandible and a decrease in mandibular plane
angle and gonial angle
• c. Lingual tipping of lower incisors.
• d. Improvement in skeletal and soft tissue profile.
Therefore, chin cup works well in patients with reduced or normal
lower anterior face height but is contradicted in long face patients.
• According to TM Craber, ideal patients for chin cup therapy are
those suffering from:
• • A mild skeletal problem with the ability to bring the incisors.end-
to-end or nearly so.
• • Short vertical face height
• • Normally positioned or protrusive, but not retrusive lower
incisors.

30. Types of Chin Cup
• 1. Occipital puIl chin cup derives anchorage from the
occiput region. This is used in Class III cases with mild
to moderate mandibular prognathism, who can bring
their incisors in an edge-to-edge position at centric
relation. Patients with short anterior facial height also
benefit from this type of chin cup. This is the more
commonly used chin up.
• 2. Vertical pull chin cup derives anchorage from the
parietaI region. It is indicated in high angle cases or
long face patients as it helps to close the angle of the
mandible and increase the posterior facial height.

32. • Commercially Available
• • Soft Elastic appliance
• • Hickham-type appliance
• • Unitek design
• • Summit design

34. THANK YOU