Mechanics Biomechanics in orthodontics
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Center of resistance
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Center of resistance • Cres varies with root length and alveolar crest height
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Single point force
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Single point force
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Moment If the line of action of a force is at a distance from the Cres, the force will produce some rotation. The potential for rotation is measured as a moment
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Moment Magnitude Direction Clockwise Counter- clockwise
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Moment of force
First order
second order
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third order
Couple
Two equal and opposite forces separated by a perpendicular distance. Equal and opposite forces that are not collinear.
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Moment of couple
first order
second order
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Moment of couple
Third order rotation where the two forces of the couple are not located equidistant from Cres www.indiandentalacademy.com
Additive and subtractive couples
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Additive and subtractive couples
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Equillibrium Sum of the forces acting in any plane equal zero. Sum of the moments in any plane equal zero.
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