growth modification and head gears

Dr. Rashid Mahmood

Discrepancies

Skeletal

Dental

Soft-tissues

Three dimensions

↔Transverse

→Sagittal

↕Vertical

Transverse Discrepancies

Vertical Discrepancies

Sagittal Discrepancies

Sagittal Discrepancies

Sagittal Discrepancies

In Orthodontics

Definition: Removable or fixed orthodontic appliances which use

forces generated by the stretching of muscles, fascia and

/ or Peridontium to alter skeletal and dental

relationships.

stretching of muscles, fascia and

/ or Peridontium

Form follows function

Form follows function

“If compensatory, adaptive lip and tongue function could exacerbate excessive over-jet in class II-type malocclusions and if abnormal

swallowing and prolonged finger-sucking habits could create anterior

open-bite and narrow maxillary arches, could not the same muscles be used to correct these and other problem????”

Background Functional appliances are conceptually based on

Moss’ functional matrix theory

Functional matrix theory proposes that functional matrices, tissues like muscles and glands influence skeletal units such as jaw bones and ultimately control their growth

The appliances used to improve functional relationship of dento-facial structures by eliminating unfavorable developmental factors and

improving the neuromuscular environment enveloping the developing occlusion

Function

Muscular Action

Effect on dento-alveolar development

What they do…..? Alter the neuromuscular environment of oro-facial region to improve

occlusal development and/or craniofacial skeletal growth

Utilize muscle forces to effect bony and dental changes

Disarticulate the teeth

Encourage new mandibular position

Require a tight lip seal during swallowing

Selectively alter the eruptive path of teeth

When???

When??? Functional appliance treatment should be started before

the pubertal growth spurt

This is the time when the mandible may exhibit increased growth which may be influenced

Duration---------------------------10-12 hours a day

These appliances should be worn at night-time as this is when growth takes place

INDICATIONS

1. Growing ages (Mixed dentition and/or early permanent dentition)2. Skeletal Considerations (Sagital correction of class II &III)

Skeletal Class II with Short mandiblea) Class II division 1b) Class II division 2 (Convert div 2 to div 1)

1. Vertical Considerations

a) Normal to low angle cases2. Dental Considerations

a) Local irregularity & rotation of incisors especially upper incisorsb) Crowding or dental compensation (Pre-functional Orthodontics

require3. Open bite/ deep bite correction

4. Cross bite correction

5. To correct mal-forming dysfunction

CONTRAINDICATIONS1. Children with neuromuscular disorders

a. Poliomyelitis

b. Cerebral palsy

2. Compliance

3. Hyperdivegent faces

4. Unfavorable growth

5. Protruded lower incisors

6. Severe crowding

7. Age

Treatment Principles Force Application: Compressive stress and strain act

on the structures involved resulting in primary alteration in form and secondary adaptation in function e.g all removable appliances

Force Elimination: Abnormal and destructive environmental influences are eliminated to allow optimum development

like lip bumpers and frankel buccal sheilds

Mode of Action

Functional Appliances influence facial skeleton through condylar and sutural areas.

Goal is to

Use the functional stimulus of oro-facial muscles , channeling this stimulus to the jaws, condyles and teeth to bring the change.

Purely functional and intermittent forces

Limitations Adult Age(Ineffective in adults)

High Angle Cases(Increases vertical height of patient)

Compliance

Precise detailing of tooth position not possible

Crowding (Cases with ALD are difficult to manage)

Precise correction of Incisor inclination not possible

Increased lower incisor inclination (They tend to increase lower incisor

inclination & thus proper Sagital correction may not be possible if not properly

managed)

Functional appliances if used properly & at right time then

they help in improving the profile and eliminating the need

for Orthognathic Surgery

TYPES

Active

Passive

Active appliances reposition the mandible so that the condyle is forced out of the glenoid fossa and this in turn is thought to stimulate the posterior/superior growth of the condyle.

Passive appliances act by repositioning the musculature associated with the mandible so that the jaw bone itself responds by growing to the new equilibrium position

FUNCTIONAL

APPLIANCES

SIMPLE

FUNCTIONAL

APPLIANCES

REMOVABLE

FUNCTIONAL

APPLIANCES

FIXED

FUNCTIONAL

APPLIANCES

SIMPLE FUNCTIONAL APPLIANCES

Force elimination appliances e.gOral shields,Tongue cribs ,Habit breakers, Lip bumpers

JAW ORTHOPEDICS APPLIANCES

REMOVABLE FUNCTIONAL APPLIANCES FIXED FUNCTIONAL APPLIANCES

TYPES

Tooth Borne

Tissue Borne

Lip bumper Can be used for both mand and

maxilla Uses the muscular force from

upper or lower lip to provide distal force specially to molars

In lower arch headgear is less acceptable so lip bumper is useful

Remove soft tissues forces from labial aspect

Result increased lower incisor inclination by influence of tongueThis can be reduced by placing it as low as possible in labial sulcusso that upper part of lip is in contact with teeth

Simple functional appliances

Simple functional appliances

Oral screens Forerunner of functional

regulator

Consists of vestibular shieldswhich holds the lip away from allteeth except upper incisors b/cpressure from lips is transferredto U I and acts to move thempalatally

Can be used in mixed dentitionand aids patient with digitsucking

Jaw Orthopedic Functional

Appliances

Removable Functional Appliances

TOOTH BORN MONOBLOCK ACTIVATORS BIONATORS TWIN BLOCKS MAGNETIC APPLIANCE

TISSUE BORN FRANKEL FUNCTIONAL APPLIANCE

Fixed Functional Appliances

Flexible Fixed Functional Appliances (FFFA) Rigid Fixed Functional Appliances (RFFA) Hybrid Appliance Fixed version of RFA (fixed twin block , dynamix appliance) Elastics

TYPES MYOTONIC

Depend upon displacement of mandible in AP and vertical plane. e.g Activators

MYODYNAMIC

Not only translate the mandible AP & vertically but also attempt to utilize and translate muscular movements e.gBimler appliance

Passive functional appliances Frankel

Active functional appliances Removable active functional appliances

Bionator

Active functional appliances Removable active functional appliances

activator

Active functional appliances Removable active functional appliances

Twin-block appliance

Active functional appliances Fixed active functional appliances

Herbst

Andresen Activator Mono-block

As upper and lower plates appear joined together

Activator

Norwegian appliance

Viggo Andersen

Modified Andresen–Häupl-type activator

Class II cases Div I

For better control of lower incisor inclination,

the lower incisors are covered with acrylic,

which is relieved on the lingual surface

Correct overjet, overbite and molar relationship

during active growth

Labial bow to prevent incisors proclination

Maximum extension of lower lingual flanges in order to redistribute the force on mucoperiostium of mandible

Coffin spring instead of palatal plate

Canine loops ----- screening loops of bionator and buccal shields of FR.

Difficulty in speech

Needs removal during eating

Arch expansion cannot be carried out simultaneously

Limitations

Labial view of the Andresen appliance. The picture shows labial Bow in 0.8mm S.S wire with tubing and lower incisal capping.

Andresen

Models removed

Andresen

Lingual or palatal view

Andresen

Buccal Views

Andresen

FRANKEL APPLIANCE

FRANKEL CORRECTOR

FUNCTIONAL REGULATOR

Dr. Rolf Frankel

FRANKEL APPLIANCE

FRANKEL CORRECTOR

FUNCTIONAL REGULATOR

Dr. Rolf Frankel

Passive functional appliance

Essentially tissue borne

Appliance of choice in class II due to mandibular retrusion.

Used in early mix dentition.

Has direct effect on neuromuscular system.

Causes anterior advancement of mandible and increase in LAFH.

Expands dental arches.

FUNCTIONAL REGULATOR

Oral vestibule is used as operational basis for the treatment of dentoalveolar discrepancies.

It combines the principles of Anderson’s appliance and oral screen.

Mode of action depends upon the relieving and lifting the pressure on teeth from lips and cheeks, so that the jaws can be allowed to grow and the teeth can be guided to move into new more favorable position.

Frankel Appliance

The wire assembly anchors the appliance on the maxillary arch at the mesial embrasure of the of first molar.

Frankel ApplianceRolf Frankel

A cross palatal stabilizing wire on the maxillary arch.

FUNCTIONAL REGULATOR

FR I

a. Class I

b. Class II div 1 <5mm

c. Class II div 1 >7mm

FR II Class II div 2

FR III Class III

FR IV Open bite & mild bimax

FUNCTIONAL REGULATOR

FR I

a. Class I

It is mainly used to treat cases of Class Imalocclusion with minor to moderate crowdingor arrested development of dental bases.

It can also be used in class I malocclusion withdeep bite.

FR I Appliance

Labial view

The components include:Upper

• Palatal wire 6 / 6 in 0.9mm S.S wire.• Canine wires 3 / 3 in 0.9mm S.S

wire.• Labial Bow 2 / 2 in 0.9mm S.S wire.

Lower • Lip Pads and Joining wires in 0.9mm

S.S wire.• Hanger wires 5 / 5 in 0.9mm S.S

wire.• Lingual Pusher Springs 3 / 3 in

0.7mm S.S wire.

FR I Appliance

Buccal view of the Frankel appliance.

FR I Appliance

Frankel appliance - lingual / palatal view.

FR I Appliance

Frankel appliance with upper model removed.

FR I Appliance

Frankel appliance with lower model removed.

FUNCTIONAL REGULATOR

FR I

b. Class II div 1 where over-jet is <5mm

c. Class II div 1 where the over-jet is >7mm

FUNCTIONAL REGULATOR

FR II Class II div 2

Prior to the functional therapy the incisor need to be aligned

FR II Appliance

Buccal Shields

Labial Pads

Labial Bow

Canine Clasps

Occlusal Rests

Palatal Arch

1. Flexible Appliance

2. The lingual and labial segments in lower portion encourage holding the mandible in a postured

position to alter the lip behavior.

3. By retraining the facial muscles & muscles of mastication to occupy new position.

4. The maxilla & mandible will be influenced to grow into corrected position.

5. Stretching of periosteum, osteoblastic activity & thus the bone formation.

FUNCTIONAL REGULATOR

FR III Class III

Mild Class III cases

The correction of class III Malocclusion is by dento-alveolar means, not because of skeletal growth modification

Registration of Bite Varies with the type used.

Move mandible forward by 4 – 6 mm.

Or edge to edge contact of incisors

2.5 to 3.5 occlusal clearance.

Correction of sagittal discrepancy in 2 or 3 stages.

3 dimensional effect of FR

Bionator 1.Light Appliance 2.Better Compliance 3.Full Time Wear

Timing for Bionator Therapy

Effective and stable when it is initiated immediately before the pubertal growth spurt. Optimal timing to start treatment with the Bionator is when a concavity is evident at the lower borders of both the second and the third cervical vertebrae (CVMS II).

In the long term, the amount of significant supplementary elongation of the mandible in subjects treated with the Bionator during the pubertal growth spurt is 5.1 mm more than that in untreated subjects with class-II malocclusion. Significant increments in mandibular ramus height and for a significantly more backward direction of condylar growth.

• Used in mix dentition.

• Major indication is in extremely deep bite.

• Used to bring mandible in forward position and to increase LAFH by eruption of posterior teeth…California Bionator.

• Can be used to close bite and maintaining bite.

• Protusion springs may be used in class II div2

Bionator

Lingual horseshoe of acrylic

Palatal spring

(Reverse coffin

spring)

Facets in the acrylic

which accepts maxillary

& mandibular teeth &

hold them in postured

position

Labial Bow

Twin BlockIndications

Class II div 1 Distal molar and canine relationship of at least half premolar

width Overjet more than or equal to 5mm Protrusion of maxillary incisors Class II skelatal type ANB≥ 4 Occlusal development ..late mixed dentition or early

permanenet dentition Normal & low angle cases

Effects of twin block Skeletal effects: mandibular length increses,during 1 yr, restrains

maxilla Dentoalveolar change: upper incisors tip back Lower incisors move forward Overjet reduction.,.(correction achieved by skelatal and dentoalveolar

reduction Correction of buccal segment achieved by combination of distal movement

of upper molars &forward movement lower molars ANB reduction Increased vertical dimensions..(inc lower facial height)mandibular plane

angle increases Reduction of facial convexity

Contraindications TMJ problems

Sk assymetries

Syndromic pts

Twin Block

Adams Clasp

Labial Bow

Inclined Plane

Modified

Adams Clasp

Bite blockBite block

Inclined Plane

In Function

Expansion Screw

ClarK 1988

“where there is a will there is a way”

Chapter 13

Jaw Orthopedic Functional

Appliances

Removable Functional Appliances

TOOTH BORN MONOBLOCK ACTIVATORS BIONATORS TWIN BLOCKS MAGNETIC APPLIANCE

TISSUE BORN FRANKEL FUNCTIONAL APPLIANCE

Fixed Functional Appliances

Flexible Fixed Functional Appliances (FFFA) Rigid Fixed Functional Appliances (RFFA) Hybrid Appliance Fixed version of RFA (fixed twin block , dynamix appliance) Elastics

• Fixed functional.

• should be used in permanent dentition.

• Easily tolerated by the patient.

• Should be changed after some time .

Fixed Functional AppliancesAdvantages Continuous stimulus for mandibular growth (24 hr use) They are smaller in size permitting better adaptation to functions such as a

mastication, swallowing, speech and breathing. Non-compliance Class II devices, which are able to treat Class II malocclusions

successfully, while reducing the need for patient co-operation and overall treatment time. Allows greater control by the orthodontist.

Disadvantages Application of force is transmitted directly to the teeth through a support system, the main disadvantage that may be encountered is dental movement that takes

place during treatment

APPLIANCE DISCRIPTION Can be compared to the artificial

joint between maxilla & mandible.

A bilateral telescopic mechanism keeps the mandible in continuous anterior position.

Appliance consists of a tube to which plunger fits. Tube is fixed to the distal end of maxillary molars & rod into the lower first premolars.

Herbst Appliance The Herbst appliance consists of two tubes, two plungers, axles and screws Type I is characterized by a fixing system to the crowns or bands through the use

of screws. It is necessary to weld the axles to the bands or crowns and then fix the tubes and

plungers with the screws Type II has a fixing system that fits directly onto the archwires through the use of

screws Disadvantage is the fracture of archwires

Type III is for anchorage

Type IV has a fixation system with a ball attachment, which allows greater flexibility and freedom of mandibular movement.

Disadvantage in relation to other similar appliances is that it needs brakes to stabilize the joint. The brakes are small and sometime difficult to fit. When a fracture occurs or a brake is lost, the appliance comes loose

FFF-ApplianceJasper Jumper

Jasper Jumper Herbst Appliance

Indicationsof FFFA Class I (An anchorage reinforcement)

Class II division 1 and 2

Class III malocclusions

Molar distalization

Midline discrepancy

Flexible Fixed Functional AppliancesInter-maxillary torsion coils, or fixed springs.

Advantages

Elasticity Flexibility Allow great freedom of movement of the mandible Lateral movements can be carried out with ease

Disadvantages

Fractures can occur both in the appliance itself (mainly in areas that have more acute angles) and in the support system (mainly in the lower arch)

If on one hand flexibility is an advantage, on the other hand it does tend to produce fatigue in the springs Tendency of the patient to chew on the appliance, possibly contributing to breakage or damage. It is not possible for the patient to completely open his mouth, depending on the way the system is fixed

onto the lower arch, good opening can be achieved. Expansive & replacement of broken parts adds cost Inventory Unhygienic but covering of springs make them hygienic

Mechanism of Action FFFAs allow the patient to close in centric relation

When the patient closes in centric relation, the contour of the bow should be significantly increased

By slightly overactivating the appliance in centric relation, the patient will automatically position the mandible forward. This is a natural response to decrease the force module and alleviate discomfort.

Clinical Relevance

In brachyfacial cases, due to their strong musculature, it is necessary to use more force (greater activation) than in dolicofacial cases.

If the patient has large cusps with good intercuspation, it will be necessary to exert greater activation on the spring.

Greater force for orthopedic effects while lesser for dento-alveolar movements

To maximize the dentoalveolar movements in the upper arch and minimize any loss of anchorage in the lower, the upper archwire is not tied back.

It can be used to obtain maximum anchorage, holding upper molars back as the upper incisors are retracted.

Unwanted Effects Due to the intrusive force on the upper molars, a posterior open bite is common

as well as posterior expansion due to the deflected force module.

Tendency for the lower molar to rotate mesiobuccally, causing a mild posterior

crossbite especially when the second molars have not been banded

Proclination of lower incisors..

Not recommended in mixed dentition, especially late mixed dentition to avoid

unwanted dental movements.

Jasper Jumper Intrusion and distalization of the upper molars, with occasional opening of the

posterior bite similar to that seen with a Herbst ppliance.

Some indication of condylar growth.

Anterior migration of the mandibular teeth through alveolar bone.

Intrusion of the lower incisors.

Advantage

comfortable because of its covering.

Disadvantages

The large inventory that must be kept,

the coating material may degrade

Fractures

Contd. Canines can be retracted against

mandibular dentition.

As the force modules cause asymmetric forces, it can be used to treat dental asymmetries.

Causes mandibular advancement and increase in LAFH.

Can be used in post surgical stabilization of class II patients.

Indications.

Dental Class II malocclusion.

Skeletal Class II with maxillary excess as opposed to mandibular deficiency.

Deep bite with retroclined mandibular incisors.

Midline Correction

Contra-indications.

Cases predisposed to root resorption.

Dental and skeletal open bites.

Vertical growth with high mandibular plane angle and excess lower facial height.

Minimum buccal vestibular space.

Rigid Fixed Functional Appliances RFFAs do not easily fracture but neither do they have elasticity or flexibility.

After fitting and activation they do not allow the patient to close in centric relation. This means that the mandible is in a forward position 24 hours a day creating greater stimulus for mandibular growth than with FFFAs.

Skeletal effects produced with this type of appliance are greater than with FFFAs

Mechanism of Action

Telescopic mechanism which encourages forward repositioning of the lower jaw as the patient closes into occlusion

Indications.

Dental Class II malocclusion due to retrognathic mandible Skeletal Class II mandibular deficiency.

Deep bite with retroclined mandibular incisors. They can be used as an anterior repositioning splinting patient with TMJ disorders.

Residual growth can be utilized in post adolescent patients. Can be used in mouth breathers.

Contra-indications.

Cases predisposed to root resorption.

Dental and skeletal open bites.

Vertical growth with high maxillomandibular plane angle and excess lower facial height.

TYPES OF APPLIANCE Bonded herbst (High Angle Cases)

Banded herbs

Flip locked herbst

Crowned herbst

The Flip-Lock Herbst Appliance

Reduced number of moving parts that can lead to breakage or failure.

Easy to use

Comfortable

Instead of a screw attachment, it has a ball-joint connector so it needs no retaining springs.

Less chairside time activation

Bonded Herbst Appliance

High Angle Cases

It is a wire reinfofced acrylic splint.

The pivots are fixed to the wire framework at distobuucal aspect of the upper first molar mesial aspect of lower first premolar.

Tube is fitted to the pivot in the upper molars & shaft is fixed to mandibular premolar region

BANDED HERBST Upper & lower first premolar & first molars

are banded.the tubes are fixed to pivots soldered to distobuccal aspect upper first molars.

The shaft or rods are fixed to pivots soldered to lower first premolar band.

CROWNED HERBST

Hybrid Functional Appliances

Hybrid appliances are specifically and individually tailored to exploit

the natural processes of growth and development.

These appliances blend several components designed to address

specific problems

Asymmetric mandibular deficiency or facial asymmetry in children

Condylar fracture

Fixed Version Of RFA

• Dynamax Appliance

• Fixed Twin Block

• Magnetic Appliances

• Elastics

Fixed version of RFA

Clip-on Fixed Functional Appliance Advantages of the Appliance

Patient co-operation is not required.

It works for 24 hours a day.

A full fixed appliance can be placed at the same time as the Class II correction is being carried out.

Treatment time is short because of full time wear.

There is no transitional phase between functional phase and the fixed phase so treatment time reduced.

Overlap of the functional and fixed phase further reduces treatment time.

It is less bulky than other functional appliances.

Fixed version of RFAJO March 2001

Clip-on Fixed FA

Inclined Planes

Occlusal blocks with lingual tube attachments

Occlusal blocks with palatal

tube attachments.

Disadvantages of the Appliance

Breakage of the Appliance

Construction of the Appliance.

Oral Hygiene Problems

Airways Clearance

Clip-on Fixed Functional Appliance

The results showed that this appliance was effective in correcting Class II malocclusion; the noncompliance rate was only 6%

Extra-oral force

Dento-facial orthopedics

Head Gears Orthopedic appliance that control growth of facial

structures

Various designs.

Used with growing patients.

USES OF HEAD GEAR CORRECTION OF SKELETAL CLASS II AND REDIRECTION OF GROWTH

;(excess growth of maxilla/deficient growth of mandible)Head gear restrain the forward and downward growth of maxilla by holding back the growth of upper jaw, allowing the lower jaw to catch up and thus the correction of class II.

MOLAR DISTILIZATION.head gear may be used to distalize maxillary molar to correct the class II molar relation ship or to gain space for relief of crowding.

AS AN ANCHORAGEIn some situations ,to maintain the bite, the orthodontist will not

want the back teeth to come forward. The headgear serves to hold them back to maintain anchorage.

USES OF HEAD GEAR REINFORCEMENT OF ANCHORAGE.

head gear can be used to reinforce anchorage in high anchorage cases.

MOLAR ROTATION.can also be brought about with the inner bow of headgear.

CORRECTION OF SKELETAL CLASS III.(deficient growth of maxilla/excess growth of mandible).; by protraction or reverse pull head gear that causes the anterior displacement of maxilla.

CORRECTION OF SKELETAL CLASS II AND REDIRECTION OF GROWTH ;(excess growth of maxilla/deficient growth of mandible)

CORRECTION OF SKELETAL CLASS II AND REDIRECTION OF GROWTH ;(excess growth of maxilla/deficient growth of mandible)

CORRECTION OF SKELETAL CLASS III

TYPES OF HEAD GEAR

High pull

Cervical pull

Combination pull

Reverse pull

Asymmetric Head Gear

TYPES OF HEAD GEAR

TYPES OF HEADGEAR

High pull Combination pull

Cervical Pull Reverse pull

Asymmetricheadgear

COMPONENTS PARTS OF HAEDGEAR

. Face bows;( Inner and outer bow)

. Release modules

. Straps or cushions

. Other items.

FACE BOW STYLES. KLOEHN

Regular

Cushion Loop

J-HOOK

ASHER

BITE PLATE

FACEBOW STYLES

Kloehn style

Bite plate

Asher facebow

Cushion loop

J -hook

BIOMECHANICS OF HEAD GEAR CENTER OF RESISTANCE OF MAXILLA AND MOLAR TOOTH.

BIOMECHANICS OF HEADGEAR The relation ship of line of action of force to the

center of resistance of maxilla or first molar determines whether translation (bodily )or rotation (tipping) takes place.

When a force does not pass through the center of resistance of the maxilla/molar, A moment is produced.

The direction of line of force can be changed by adjusting the length and position of outer bow.

High Pull Head Gear Bodily movement of molar

(no tipping) when line of force is passing through the center of resistance of molar.

Both backward and upward movement of molar.

When line of force is above CR --- mesial tip of crown and distal tip of root.

When line of force is below CR --- mesial tip of root and distal tip of crown.

Bodily movement of molar (no tipping) when line of force is passing through the center of resistance of molar, as determined by the outer bow length and position

Both backward and downward movements of molar.

When line of force is above CR ---mesial tip of crown and distal tip of root.

When line of force is below CR ---mesial tip of root and distal tip of crown.

The outer bow is always longer than that used in High pull.

Low Pull/Cervical Head Gear

BIOMECHANICS OF HEAD GEAR Similar considerations

apply to maxilla. Unless the line of force is through the center of resistance, rotation of maxilla occurs.

Control of line of force is easier when face bow inserted into the splint covering all teeth.

With all teeth splinted; it is possible to consider the maxilla as a unit and to relate the line of force to the center of resistance of maxilla.

RULE TO CHECK WHETHER THE LINE OF FORCE IS THROUGH THE CENTER OF RESISTANCE IN HIGH PULL AND CERVICAL PULL

HEADGEAR

In order to determine the proper position of outer bow. Use index finger to apply pressure in direction of head gear selected.

A)In case of high pull headgear we move index finger below the outer bow, pushing up and back. As the finger is moved on the outer bow applying force. The bow will move up between the lips.

B)In case of cervical pull headgear we move index finger above the outer bow, pushing down and back. As the finger is moved on the outer bow applying force. The bow will move down between the lips.

BIOMECHANICS OF HEADGEAR When the bow moves up, the roots of

maxillary first molar will move distally.

. When the bow moves down, the rootsof maxillary first molar will movemesially and crown distally.

. When the bow does not move. Theforce is through the center ofresistance of the maxillary first molarand molar will move bodily and notrotate.

BIOMECHANICS OF HEAD GEAR EFFECT OF THE LENGTH OF OUTER BOW.

The longer outer bow bend up and shorter bow bend down could produce the same line of force through the center of resistance of molar.

High Pull Head Gear Derives anchorage from parietal region. It

produces intrusion and distalization of teeth.

INDICATIONS. Open bite cases. High mandibular plane angle. Long face cases with an increase in lower

anterior facial height.

High pull headgear can be used as.

HIGH PULL HEADGEAR TO MOLARS. HIGH PULL HEADGEAR TO MAXILLARY

SPLINT HIGH PULL HEADGEAR TO FUNCTIONAL

APPLIANCE.

CERVICAL HEAD GEAR

The anchor unit in this head gear is nape of neck. It causes extrusion and distalization of molars along with distal movement of maxilla.

Indications:

short face,class II

Anchorage conservation.

early treatment of classII

Combination pull Headgear

Derives anchorage from at least two regions ; the neck and occiput. It causes distal and slight superior force on maxilla and dentition.

Protraction head gear. The rationale for protraction headgear is to apply heavy force

on the mid face in order to advance the maxilla anteriorly.

In this type inner bow is bent to achieve distal insertion ,outer bow is modified to make hook in premolar region for elastic attachment.

The center of resistance of mid face is difficult to locate but most studies shows it 5-10mm below the orbit.

Protraction head gear. A line of force closer to

center of resistance of mid face will deliver a translatory force and line of force closer to occlusal plane has rotational force.

Petit Face Mask For the protraction of

maxilla and maxillary dentoalveolar segments.

developing Class III pattern.

Cleft lip and palate patients.

Extra-oral elastics (heavy)

Asymmetric head gear. Asymmetic force is

achieved with a head gear by using an asymmetric outer bow,can be useful in regaining bilateral but asymmetric lost space.

Time, Duration and Force of Headgear Therapy. FORCE. 500 TO 700gm(orthopedic )150-

200gm(orthodontic force).

DURATION 12 -14hrs /Day, emphasis on wearing it from early morning.

Treatment Duration. 12 TO 18 Months.

TREATMENT EFFECTSSKELETAL EFFECTS Frontomaxillary,zygomaticotemporal,zygomaticomaxil

lary n pterygopalatine r most imp growth sites for development of maxilla.

head gears act by compressing the sutures thus restricting the normal downward n fowad growth of maxilla.

DENTAL EFFECTS Distalization of molars. Extrusion and intrusion of molars

SIDE EFFECTS OF HEAD GEAR

Compensatory erruption of max And mand molars but can be controlled by fixed lingual arch.

Distal tipping of max molars.

Increased facial height.

SIDE EFFECTS OF HEAD GEAR