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Presented by Dr. Prasad Gayake

Guided by Dr. S. S. Chitko Dr. N.D. Gulve

Electromyography & Its ApplicationIn Orthodontics

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Electromyography -

Definition

It indicates ?

Electromyogram

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Muscle -1. Skeletal muscle

2. cardiac muscle

3. smooth muscle

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Structure ofskeletal muscle

Muscle fibre

EpimysiumPerimysium

Endomysium

Myofibril

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Resting membranepotential

What is it ?

-85 to -90 mV Ionic basis - Na-K

pump

-selectivepermeability

of ions

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Neuro-muscularjunction

Structure

Function

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Action potential

Depolarisation

Repolarisation

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Motor unitStructural basis of

electromyography

Each motor neuron -supplies group ofmuscle fibres

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Motor unitpotential-

- 5-8 mili seconds &

amplitude of 0.5 mV

- Biphasic

- Shows sharp spike oncathode rayoscilloscope

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Electromyographic technique

Cathode rayoscilloscope

Two types of

electrodes

1.Surface electrode

-Advantages-

Disadvantages

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2.Needle electrode

-Advantages

-Disadvantages

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1. Select the muscle

2. Select the electrode

3. Clean the surface of the muscle

4. Instruct the patient how to contract & relax5. Electrolyte paste for surface electrode

6. For needle electrode insert the needle quickly tominimise the pain

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7.Look for insertional activity, spontaneous activity

8.Number of areas sampled for needle electrode

9.Reference electrode placement10.Ask the patient to contract the muscle

11.Action potential is recorded with the help ofmoving pen in the form graph

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Results At rest , muscle

electrically inactive

Except NMJ

Contraction actionpotential produced

electric potential ofwhole muscle ----force

of contraction full contraction

disorderly group ofaction potentials ofvarying rates &

amplitudes

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Applications

Electromyographic activity in cl-II

div 1 patientsHyperactive mentalis

Hyperactivebuccinator

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Electromyographicactivity in cl-IIIpatients

Decreased activity ofmasseter & temporalis

Increased activityafter treatment (

Deguchi & Iwahara )

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Electromyographicactivity duringswallowing

Normal swallowingAbnormal swallowing

Tongue thrustswallowing

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Decreasedelectromyographic activity of

masseter duringmouth breathing-

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Electromyographic activity in thumbsucking patients

Hyperactive mentalis

Hyperactive buccinator

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Lip incompetence -

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After orthodontic therapy

Electromyographic activity in deep bite

patients- Increased temporalis activity

Postural rest position

Bruxism patients

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Thank you