HEAD GEAR

DR. ABDUL JABBAR 1

Means of applying posterior directed forces to teeth and skeletal structures from an extra oral source 2

Headgear Introduced in late 1800s Abandoned as it was thought that intra oral elastics would be as effective Reintroduced in 1940s after cephalometric developed 3

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Mechanism of action

Growth modification by changing the pattern of bone apposition at the sutures CL II correction is obtained as the mandible grows forward normally while maxillary growth is restrained Favorable mandibular growth is a must for CL II correction with HG use 6

Force is generated by head cap or neck strap through ; springs Elastic bands 7

Force is delivered to the teeth by ; Face bow J Hooks 8

classification

Distalising HG

: direction of elastic traction has a distal component Types : Occipital directed ( high) pull Combination pull Cervical directed (low) pull J-hook HG Asymmetric HG HG to mandible 9

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High Pull Headgear

Skeletal Class II with prognathic maxilla High Angle case Growing ages

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Straight Pull Headgear

Skeletal Class II with prognathic maxilla normal Angle case Growing ages

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Cervical Pull Headgear

Skeletal Class II with prognathic maxilla Low Angle case Growing ages

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High pull HG

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Combination pull HG

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Low pull HG

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J Hook HG

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A. Single pull to maxillary dentition B. Attachment of the J hooks to both maxillary and mandibular dental arches.

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Asymmetric HG

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Components

Head cap / neck strap Elastics Face bow (Inner bow, outer bow and U loop) 17

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Uses: dental

Anchorage Distalisation – single or blocks of teeth Intrusion -- single or blocks of teeth Extrusion Asymmetric movement 25

Uses: skeletal

growth modification maxilla --- suppression which is permanent even after treatment has ceased mandible --- suppression, retrusion of the chin during chin cap treatment.however catch-up mandibular growth may occur during or after pubertal growth period 26

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Factors influencing effect

Direction of force Duration of force Magnitude of force Centers of rotation 28

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Duration and magnitude of force

Orthopedic effect Principle: higher forces for comparatively smaller duration 12 ---16 oz or 350-----450 gm / side 10 ---12 hrs 33

Duration and magnitude of force

Tooth movement Principle : smaller forces for longer duration 100 --- 200 gm / side 14 --- 16 hrs Anchorage 250 --- 300 gm / side 10 hrs min.

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Magnitude of force is determined by a Strain-gauge Spring loaded assembly comes with a built in force indicator 35

FORCE MEASURING DEVICE

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Centers of rotation

Single rooted teeth ----- centroid 6_ ----- trifurcation Maxilla ----- b/w roots of 4&5 38

Resolution of forces:horizontally

Force thru center of resistance ----- bodily movement Force above center of resistance ----- distal root tipping Force below center of resistance ----- mesial root tipping 39

Resolution of forces: Vertically

Above occlusal plane ----- intrudes teeth Below occlusal plane ----- extrudes teeth 40

Problems with HG Tooth- related

Unwanted tooth movement Tipping Extrusion of 6_ may cause clockwise rotation of mand. Pt. Becomes more CLII Buccal rolling of 6_ with high pull HG Cross bite on side of movement with asymmetric HG Lingual tipping of lower incisors, clockwise rotation of mand. & increased LAFH with chin cup therapy Root resorption possibly with J hook HG 41

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Problems with HG Patient related

Co-operation biological variability growth may be unfavorable Extra / intra-oral injuries Pain Difficulty with insertion 44

Assessment of patient compliance at every visit Check for signs of use intra orally as well as extra orally Hand out Time-sheets for record of wear Offer reward 45

Extra oral injuries include injuries to eyes , eyelids, nose etc.

Most common are eye injuries Catapult type of injury very common while playing Disengagement of face bow during sleep 46

Safety

No single safety HG is best Should use safety face bow and release mechanism together Written instructions must be given to patient Risks involved should be explained told to seek medical advice if any problem arises 47

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THANK YOU

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