Biologic basis of
Orthodontic Treatment
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacadem...
Biologic basis of Orthodontic Treatment
 State

of equilibrium
 Classification of Orthodontic Forces
 Theories of Tooth...
 Why

do teeth not move under normal circumstances?

--- Equilibrium theory, which states that the forces
from the extrao...
www.indiandentalacademy.com
THE BASIS OF ORTHODONTIC TOOTH MOVEMENT
ORTHODONTIC TREATMENT IS BASED ON THE PRINCIPLE
THAT IF PROLONGED PRESSURE IS APPL...
THE TOOTH MOVES THROUGH THE BONE CARRYING
ITS ATTACHMENT APPARATUS WITH IT,AS THE
SOCKET OF THE TOOTH MIGRATES.
THIS

BONY...
Forces applied to the teeth can also affect the pattern of
bone apposition and resorption at sites distant from the
teeth,...
Theories of tooth movement
 Pressure-tension

theory
 Piezo-electric theory

www.indiandentalacademy.com
Theories of tooth movement
 Pressure-tension

theory: This is the most accepted
theory. According to this theory, wheneve...
Theories of tooth movement


a)
b)
c)

Pressure-tension theory: Can be divided into
three overlapping stages which includ...
Theories of tooth movement
Alterations in Blood flow associated with pressure
a) Increasing pressure on the tooth results ...
www.indiandentalacademy.com
Theories of tooth movement
 The

second stage involves the release of chemical
messengers
--- Primary messengers: Cytokin...
After a delay of several days, cellular elements
from adjacent undamaged areas of PDL begin to
invade the necrosed area.
O...
These osteoclasts arrive in two waves
-First wave-derived from local cell population
-Larger second wave-are brought in fr...
www.indiandentalacademy.com
Pressure-tension theory


a)
b)

Two types of resorption patterns are seen
whenever forces are applied to move teeth.
Fro...
Pressure-tension theory
a) Frontal Resorption: This is a favourable resorption
pattern which depends on:
-- Magnitude of f...
Pressure-tension theory
b) Undermining resorption : This is a resorption
pattern seen whenever heavy forces are applied,
w...
Pressure-tension theory
b) Undermining resorption :
Instead, a resorption wave is initiated from the
underside of the Lami...
www.indiandentalacademy.com
The Piezo-electric theory




According to this theory, whenever stresses are
applied to bone, it deforms and bends.
Cha...
www.indiandentalacademy.com
The Piezo-electric theory

a)
b)

Limitations:
Does not explain how the chemical mediators act
Piezo-electricity exists o...
Classification of Orthodontic forces
According to Schwarz :
a) First degree of efficiency:These are forces lower
than the ...
Classification of Orthodontic forces
According to Schwarz :
c) Third degree of Efficiency:
The forces in
this category ten...
Classification of Orthodontic forces
According to Schwarz :
b) Second degree of efficiency:This refers to force
levels mos...
Classification of Orthodontic forces
According to Schwarz :
d) Fourth degree of Efficiency: The force levels in
this group...
Classification of Orthodontic forces

a)
b)
c)

According to Proffitt :
Continuous Forces
Interrupted forces
Intermittent...
Factors affecting tooth movement
a)
b)
c)

Age of the patient and in turn, the viability of
supporting structures
Magnitud...
THE ORTHODONTIC FORCE DURATION IS CLASSIFIED1) CONTINUOUS –
2 ) INTERRUPTED3 ) INTERMITTENT-

Continuous and interrupted f...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
Factors affecting tooth movement
a)
b)
c)

Age of the patient and in turn, the viability of
supporting structures
Magnitud...
Types of Orthodontic tooth movement
a)
b)
c)
d)
e)

Tipping
Translation (Sagittal)
Intrusion
Extrusion
Rotation
www.indian...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
EFFECTS OF FORCE MAGNITUDE
THE HEAVIER THE SUSTAINED PRESSURE,GREATER
SHOULD BE THE REDUCTION IN BLOOD FLOW THROUGH
COMPRE...
Harmful effects of Orthodontic Forces
Heavy forces often result in extensive damage to the PDL
as well as root surfaces.
a...
Orthopedic forces and their effects
a) On the maxilla – Maxillary growth stimulation
or restraint is facilitated because o...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
Thank you
For more details please visit
www.indiandentalacademy.com

www.indiandentalacademy.com
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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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Copy of biologic basis tooth movement /certified fixed orthodontic courses by Indian dental academy

  1. 1. Biologic basis of Orthodontic Treatment INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Biologic basis of Orthodontic Treatment  State of equilibrium  Classification of Orthodontic Forces  Theories of Tooth Movement  Types of Orthodontic tooth movement  Orthopedic effects of Forces  Iatrogenic effects of Orthodontic forces www.indiandentalacademy.com
  3. 3.  Why do teeth not move under normal circumstances? --- Equilibrium theory, which states that the forces from the extraoral and the intraoral areas balance each other, aided additionally by the periodontium. www.indiandentalacademy.com
  4. 4. www.indiandentalacademy.com
  5. 5. THE BASIS OF ORTHODONTIC TOOTH MOVEMENT ORTHODONTIC TREATMENT IS BASED ON THE PRINCIPLE THAT IF PROLONGED PRESSURE IS APPLIED TO A TOOTH, TOOTH MOVEMENT WILL OCCUR AS THE BONE REMODELS. BONE IS SELECTIVELY REMOVED IN SOME AREAS AND ADDED IN OTHERS. www.indiandentalacademy.com
  6. 6. THE TOOTH MOVES THROUGH THE BONE CARRYING ITS ATTACHMENT APPARATUS WITH IT,AS THE SOCKET OF THE TOOTH MIGRATES. THIS BONY RESPONSE IS MEDIATED BY THE PERIODONTAL LIGAMENT, TOOTH MOVEMENT IS PRIMARILY A PERIODONTAL PHENOMENON. www.indiandentalacademy.com
  7. 7. Forces applied to the teeth can also affect the pattern of bone apposition and resorption at sites distant from the teeth, viz sutures of the maxilla and bony surfaces of the TMJ Thus, the biologic response to orthodontic treatment includes not only the response of the PDL, but also the growing areas distant from the dentition. www.indiandentalacademy.com
  8. 8. Theories of tooth movement  Pressure-tension theory  Piezo-electric theory www.indiandentalacademy.com
  9. 9. Theories of tooth movement  Pressure-tension theory: This is the most accepted theory. According to this theory, whenever pressure and tension zones exist, chemical messengers are released which will bring about recruitment of osteoblasts and osteoclasts www.indiandentalacademy.com
  10. 10. Theories of tooth movement  a) b) c) Pressure-tension theory: Can be divided into three overlapping stages which include – Alterations in Blood flow associated with pressure Formation and /or release of chemical mediators Activation of cells www.indiandentalacademy.com
  11. 11. Theories of tooth movement Alterations in Blood flow associated with pressure a) Increasing pressure on the tooth results in reduction of blood flow. If the force application continues, a zone of sterile necrosis results – Zone of Hyalinization www.indiandentalacademy.com
  12. 12. www.indiandentalacademy.com
  13. 13. Theories of tooth movement  The second stage involves the release of chemical messengers --- Primary messengers: Cytokines, Prostaglandins ---- Secondary messengers: Cyclic AMP Prostaglandin E2 has the property of stimulating both osteoblastic as well as osteoclastic activity www.indiandentalacademy.com
  14. 14. After a delay of several days, cellular elements from adjacent undamaged areas of PDL begin to invade the necrosed area. Osteoclasts appear within adjacent bone marrow Spaces & begin an attack on the underside of the Bone immediately adjacent to PDL—undermining Resorption, since the attack is from the underside Of lamina dura. www.indiandentalacademy.com
  15. 15. These osteoclasts arrive in two waves -First wave-derived from local cell population -Larger second wave-are brought in from distant Areas via blood flow. These cells attack the adjacent lamina dura removing bone in the process of Frontal resorption. Tooth movement begins thereafter.At the same time,osteoblasts recruited from PDL form bone on the tension side & begin remodeling activity. www.indiandentalacademy.com
  16. 16. www.indiandentalacademy.com
  17. 17. Pressure-tension theory  a) b) Two types of resorption patterns are seen whenever forces are applied to move teeth. Frontal Resorption Undermining resorption www.indiandentalacademy.com
  18. 18. Pressure-tension theory a) Frontal Resorption: This is a favourable resorption pattern which depends on: -- Magnitude of force -- Duration of force In this type of resorption, Howship lacunae are seen adjacent to the PDL in the frontal aspect of the lamina dura. www.indiandentalacademy.com
  19. 19. Pressure-tension theory b) Undermining resorption : This is a resorption pattern seen whenever heavy forces are applied, which compress the PDL beyond half its original size. Due to obstruction of the blood flow, osteoclasts cannot be recruited onto the frontal aspect of the lamina dura. www.indiandentalacademy.com
  20. 20. Pressure-tension theory b) Undermining resorption : Instead, a resorption wave is initiated from the underside of the Lamina dura – known as ‘Undermining resorption’ Responsible for ‘jumpy’ pattern of tooth movement, often seen with fixed appliances www.indiandentalacademy.com
  21. 21. www.indiandentalacademy.com
  22. 22. The Piezo-electric theory   According to this theory, whenever stresses are applied to bone, it deforms and bends. Charges are produced on the inside and outside, which stimulate either deposition or resorption www.indiandentalacademy.com
  23. 23. www.indiandentalacademy.com
  24. 24. The Piezo-electric theory  a) b) Limitations: Does not explain how the chemical mediators act Piezo-electricity exists only for a short period. www.indiandentalacademy.com
  25. 25. Classification of Orthodontic forces According to Schwarz : a) First degree of efficiency:These are forces lower than the threshold of stimulation to activate Orthodontic tooth movement. ---Short duration and low force balanced by the compensatory mechanisms  www.indiandentalacademy.com
  26. 26. Classification of Orthodontic forces According to Schwarz : c) Third degree of Efficiency: The forces in this category tend to interrupt circulation in the PDL (20-50 gm/sq.cm)  www.indiandentalacademy.com
  27. 27. Classification of Orthodontic forces According to Schwarz : b) Second degree of efficiency:This refers to force levels most effective in achieving Orthodontic tooth movement. (Optimum Orhtodontic force). Characterised by low but continuous forces (roughly 15-20 gm/sq.cm over the compressed PDL)  www.indiandentalacademy.com
  28. 28. Classification of Orthodontic forces According to Schwarz : d) Fourth degree of Efficiency: The force levels in this group are so excessive that they crush the PDL between the tooth and the alveolar bone in the areas of pressure. If continuous, they can cause extensive, irreparable damage.  www.indiandentalacademy.com
  29. 29. Classification of Orthodontic forces  a) b) c) According to Proffitt : Continuous Forces Interrupted forces Intermittent forces www.indiandentalacademy.com
  30. 30. Factors affecting tooth movement a) b) c) Age of the patient and in turn, the viability of supporting structures Magnitude, duration and type of forces applied Chemical agents – action of certain drugs www.indiandentalacademy.com
  31. 31. THE ORTHODONTIC FORCE DURATION IS CLASSIFIED1) CONTINUOUS – 2 ) INTERRUPTED3 ) INTERMITTENT- Continuous and interrupted forces are produced by Fixed appliances, while the intermittent forces are produced by removable appliances www.indiandentalacademy.com
  32. 32. www.indiandentalacademy.com
  33. 33. www.indiandentalacademy.com
  34. 34. www.indiandentalacademy.com
  35. 35. Factors affecting tooth movement a) b) c) Age of the patient and in turn, the viability of supporting structures Magnitude, duration and type of forces applied Chemical agents www.indiandentalacademy.com
  36. 36. Types of Orthodontic tooth movement a) b) c) d) e) Tipping Translation (Sagittal) Intrusion Extrusion Rotation www.indiandentalacademy.com
  37. 37. www.indiandentalacademy.com
  38. 38. www.indiandentalacademy.com
  39. 39. www.indiandentalacademy.com
  40. 40. www.indiandentalacademy.com
  41. 41. EFFECTS OF FORCE MAGNITUDE THE HEAVIER THE SUSTAINED PRESSURE,GREATER SHOULD BE THE REDUCTION IN BLOOD FLOW THROUGH COMPRESSED AREAS OF PDL,VESSELS ARE TOTALLY COLLAPSED NO FURTHER BLOOD FLOWS. WHEN LIGHT BUT PROLONGED FORCE IS APPLIED- •Blood flow decreases •Partially compressed PDL •Tooth moves in the socket www.indiandentalacademy.com
  42. 42. Harmful effects of Orthodontic Forces Heavy forces often result in extensive damage to the PDL as well as root surfaces. a) Crushing of the PDL – causing pain as well as mobility b) Reversible resorption of bone c) Apical Root Resorption www.indiandentalacademy.com
  43. 43. Orthopedic forces and their effects a) On the maxilla – Maxillary growth stimulation or restraint is facilitated because of the presence of sutures in the naso-maxillary complex. www.indiandentalacademy.com
  44. 44. www.indiandentalacademy.com
  45. 45. www.indiandentalacademy.com
  46. 46. www.indiandentalacademy.com
  47. 47. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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