Mechanics of tooth movement /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Mechanics of tooth movement /certified fixed orthodontic courses by Indian dental academy

  1. 1. Mechanics of tooth movement INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Scalers &vectors • Force (F=MA)_force is that which changes or tends to change the state of rest of a body or of uniform motion along a st line Force acts in three dimensions of space www.indiandentalacademy.com
  3. 3. Resultants of orthodontic force Forces with common point of application www.indiandentalacademy.com
  4. 4. Forces with different points of application Law of transmissibility of forces =external effect of force on a rigid body may be considered to have a point of application anywhere along its line of action www.indiandentalacademy.com
  5. 5. Resolving a force in to components www.indiandentalacademy.com
  6. 6. Force & movement • Center of gravity ~A point on which a free body can be perfectly balanced (C of mass) • Center of resistance~A point through which the line of action of force passes, producing translation www.indiandentalacademy.com
  7. 7. Determinants of center of resistance • Size &shape of the crown & rootroots • periodontal attachment • level &density of alveolar bone • multirooted 1~2mm apical tofurcation • 50% of root Proffit & Nikolai • 50~33% Smith & Burstone • 25~33% Nanda www.indiandentalacademy.com
  8. 8. Types of tooth movement • Translation-pure bodily movement • Pure rotation-It indicates movement of points of the tooth along the arc of a circle with cent of resist as cent of circle • Combination www.indiandentalacademy.com
  9. 9. Translation • If the line of action of an applied force passes through the center of resistance of a tooth it responds by translation in the direction of line of action www.indiandentalacademy.com
  10. 10. Moment of a force • Moment (potential for rotation) = magnitude of force * perpendicular distance from line of action to point of resistance www.indiandentalacademy.com
  11. 11. Direction of moment (positive &negative ) Combined translation & rotation www.indiandentalacademy.com
  12. 12. Rotations / Couples Couple consists of two forces of equal magnitude , with parallel but noncolinear lines of action & opposite senses Moment of couple = magnitude of forces * dist between them www.indiandentalacademy.com
  13. 13. AntiCl wise~10*50=500 gm mm Cl wise ~30*50 =1500gm mm Net ~1500-500 =1000 gm mm Force *dist ~50*20 =1000gm mm Couple is a “free vector” www.indiandentalacademy.com
  14. 14. Recap • Force ~ physical entity applied to an . . object • Moment ~turning tendency of force (pt of . reference ) • Couple ~inherent moment not relative to . any point www.indiandentalacademy.com
  15. 15. Center of rotation • Center of rotation # a point about which a body appears to have rotated www.indiandentalacademy.com
  16. 16. Center of rotation &tooth movement www.indiandentalacademy.com
  17. 17. • Hurd & Nikoli ~Point which moves the least on the line of long axis of tooth • Hocevar ~geometric point about which no moment has occurred www.indiandentalacademy.com
  18. 18. Force system &center of rotation • Only net force translation (infinity ) • net moment only rotation (cent of resist ) • moment &force ( ? ) www.indiandentalacademy.com
  19. 19. Equivalent force systems • Sums of forces in x direction are identical • Sum of forces in y direction are identical • sum of moment about any point are identical www.indiandentalacademy.com
  20. 20. Moment about any point www.indiandentalacademy.com
  21. 21. Clinical situation of canine distalization www.indiandentalacademy.com
  22. 22. Center of rotation Clockwise apical Counter clock wise incisal www.indiandentalacademy.com
  23. 23. All put together www.indiandentalacademy.com
  24. 24. M/F ratio &tooth movement 10mm Units millimeter www.indiandentalacademy.com
  25. 25. summary • Orthodontic forces are vectors • They can be combined or divided • They produce translation ,rotation ,combination • couple • center of resistance • center of rotation • M/F ratio key to controlled tooth movement • Understanding of mechanics controls one of the variable www.indiandentalacademy.com
  26. 26. www.indiandentalacademy.com Thank you For more details please visit www.indiandentalacademy.com

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