BONE CHANGES DURING
ORTHODONTIC TOOTH
MOVEMENT
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandenta...


Bone is a specialized mineralized connective tissue made up
of an organic matrix of collagen fibrils embedded in an
amo...
Classification of bone
Based on Structure.
Compact Bone or cortical bone - the
dense outer shell of the skeleton.
Cancello...
Based on the arrangement of the collagenous matrix.
Immature Bone : is subdivided into :
Woven Bone : Relatively weak ,dis...
W – Woven Bone

L – Lamellar Bone

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HISTOLOGY OF BONE

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HISTOLOGY OF BONE
Periosteum

Compact Bone
Circumferential lamellae
Concentric lamellae
Interstitial lamellae
Bony trab...
CELLS OF THE BONE
Osteoblast
Any cell that forms bone.
Differentiation of Osteoblasts
Mesenchymal stem cells differentiate...
Osteoblast

www.indiandentalacademy.com
RECEPTOR ACTIVATION
In the nucleus, different second messengers account for immediate early
gene (IEG) expression.. The tr...
Lining Cells
Lining Cells are remnants of
osteoblasts that previously laid down
bone matrix, forming a bone
membrane that ...
Osteoclasts
Osteoclasts are multi nucleated giant cells which resorb bone.
They occupy shallow pits called ‘Howship’s la...
Origin and Cell Lineage

www.indiandentalacademy.com
Differentiation of Osteoclasts
•The molecule that inhibits osteoclastogenesis is OPG (osteopotegerin)
and OCIF (osteoclast...
Structural composition of bone

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Organic Matrix
Organic matrix consists of 90% of collagen and remaining 10% is
composed of other non-collagenous molecules...
ORTHODONTIC TOOTH MOVEMENT
PEIZOELECTRIC THEORY
Bone responds to an applied strain. Strain represents a change in length....
ORTHODONTIC TOOTH MOVEMENT AS RELATED TO BONE
DEFORMATION
BIOELECTRICITY: First suggested by Farrar (1888)
Piezoelectricit...
Zengo et al (1973-74) showed that bending of bone may create negative
fields occurring in the concave aspects of the bone ...
ORTHODONTIC TOOTH MOVEMENT
The orthodontic response is divided into three elements of tooth
displacement: initial strain, ...
PRESSURE TENSION THEORY

CHANGES IN THE PERIODONTAL LIGAMENT
Progressive displacement of the tooth relative to
its osseous...
CHANGES IN THE ALVEOLAR BONE
Modeling, a change in shape or size of an
osseous structure, is achieved by
differential bone...
Remodeling of dense alveolar bone may enhance the rate of
tooth movement and replace the less mature osseous tissue
formed...
CELLULAR EVENTS
 The activation of osteoclast may occur because of the integrins on
osteoclast cell membrane with protein...
How do osteoclasts work?
The ruffled border area carries out the
resorption process itself.. Osteoclasts contain large
amo...
Reversal
The reversal phase lasts from 7 to 14 days
The resorption bays are now devoid of osteoclasts and are occupied by
...
Bone matrix formation
Begins with the deposition by the osteoblasts of osteoid,. The second stage in bone
formation is min...
Bone mineralisation
2 mechanisms.
A) Matrix Vesicle :The matrix vesicle contains alkaline phosphatase, pyro­
phosphates, C...
B) Heterogeneous Nucleation : Non­collagenous proteins act as nucleators
and others may act to control crystal growth. Dep...
Non Collagenous Molecules
Name
Osteopontin
Osteonectin
Bone Sialo
Protein
GLA Protein

Composition
Phosphoprotein
Phosphop...
Growth Factors
FGF

:

IGF

:

TGF, PGDF

:

Interleukin 1

:

Tumor necrosis factor:

Increase osteo blastic precursor po...
Systemic Factors
PTH, 1,25 - Dihydroxy Vitamin D3, estrogen
Role of alkaline phosphates
hydrolyzes phosphate ions from org...
HISTOLOGICAL ASPECT
 Primary compacta is formed by
woven bone which fills in with lamellar
bone to form primary osteons.
...
SUTURES

The osteogenic layer of the suture is called
the cambium, and the inner leaf the
capsule. Between these two layer...
Rapid palatal expansion.- the adjacent expanded suture experienced
hemorrhage, necrosis, and a wound healing response. Cha...
Functional appliances exert the skeletal effect by inducing the action
of masticatory muscles expressed by multiple lines ...
Factors Regulating Tooth movement
 Growth;
 Bone density
 Type of tooth movement
 Role of Periodontium
 Duration and ...
Parathyroid hormone
effects on bone resorption
effects on bone formation
effects on Ca++ homeostasis
Calcitonin
short term...
Prostaglandins
bidirectional effect on osteoclasts - an immediate transient effect
to slow bone resorption and a sustained...
Thank you
For more details please visit
www.indiandentalacademy.com

www.indiandentalacademy.com
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Bone changes during ortho. tooth movement dr.anusha /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
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Bone changes during ortho. tooth movement dr.anusha /certified fixed orthodontic courses by Indian dental academy

  1. 1. BONE CHANGES DURING ORTHODONTIC TOOTH MOVEMENT INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2.  Bone is a specialized mineralized connective tissue made up of an organic matrix of collagen fibrils embedded in an amorphous substance with mineral crystals precipitated within the matrix. The main functions of bone are two fold. Function of Support Reservoir Function www.indiandentalacademy.com
  3. 3. Classification of bone Based on Structure. Compact Bone or cortical bone - the dense outer shell of the skeleton. Cancellous Bone or trabecular bone comprises of a system of plates, rods, arches and struts traversing the medullary cavity encased within the shell of compact bone. Based on development Intramembranous bone – Eg., Bones of cranial vault, maxilla, etc. Intracartilagenous bone – Eg., www.indiandentalacademy.com Vertebra, ribs, base of the skull, etc
  4. 4. Based on the arrangement of the collagenous matrix. Immature Bone : is subdivided into : Woven Bone : Relatively weak ,disorganized and poorly mineralized. The first bone formed in response to orthodontic loading usually is the woven type. Bundle bone Bundle bone is a functional adaptation of lamellar structure to allow attachment of Sharpey's fibers Mature Bone or Lamellar bone Lamellar bone a strong, highly organized, well-mineralized tissue. Adult human bone is almost entirely of the remodeled variety: secondary osteons and spongiosa.. www.indiandentalacademy.com
  5. 5. W – Woven Bone L – Lamellar Bone www.indiandentalacademy.com
  6. 6. HISTOLOGY OF BONE www.indiandentalacademy.com
  7. 7. HISTOLOGY OF BONE Periosteum Compact Bone Circumferential lamellae Concentric lamellae Interstitial lamellae Bony trabeculae Bone Marrow www.indiandentalacademy.com
  8. 8. CELLS OF THE BONE Osteoblast Any cell that forms bone. Differentiation of Osteoblasts Mesenchymal stem cells differentiate into osteoblasts when they are exposed to bone morphogenic proteins (BMP). Cbfa1 is necessary for osteoblast differ­entiation. www.indiandentalacademy.com
  9. 9. Osteoblast www.indiandentalacademy.com
  10. 10. RECEPTOR ACTIVATION In the nucleus, different second messengers account for immediate early gene (IEG) expression.. The transcription of the IEGs (c-fos, c-jun, and egr-1) has been shown to increase when cells are exposed to cytokines, growth factors, or mechanical stimulation. Protein products from the c-fos and c-jun genes form activator protein­1 (AP­1) which regulates osteoblast differentiation. Functions of osteoblasts production of the proteins of bone matrix type I and IV collagen and other non collagenous proteins Osteoblasts secrete the growth factors. Osteoblasts mineralize newly formed bone matrix. Osteoblast may be required for normal bone resorption to occur. Functional lifespan of osteoblasts may range from 3 – 4 months to 1­5 years www.indiandentalacademy.com
  11. 11. Lining Cells Lining Cells are remnants of osteoblasts that previously laid down bone matrix, forming a bone membrane that controls ion fluxes into and out of bone. Osteocytes As osteoblasts secrete bone matrix, some of them become entrapped in lacunae and are then called osteocytes. www.indiandentalacademy.com
  12. 12. Osteoclasts Osteoclasts are multi nucleated giant cells which resorb bone. They occupy shallow pits called ‘Howship’s lacunae’ on flat bone surfaces. Positive staining for tartarate - resistant acid phosphatase. The part of an osteoclast that is directly responsible for carrying out bone resorption is a transitory and highly motile structure called its ruffled border Their lifespan is uncertain, though it may be as long as 7 weeks. www.indiandentalacademy.com
  13. 13. Origin and Cell Lineage www.indiandentalacademy.com
  14. 14. Differentiation of Osteoclasts •The molecule that inhibits osteoclastogenesis is OPG (osteopotegerin) and OCIF (osteoclastogenesis inhibiting factor).OPG is secreted by osteoblasts and blocks the formation of osteoclasts •Osteoclast differentiation factor (ODF) or OPG-L was able to induce osteoclastogenesis. •The ratio of OPG/OPG-L regulates the osteoclast' s lifecycle •Cytokines TNF, interleukin-1 [IL-1 ], prostoglandin E2 [PGE2] and growth factors (TGF-B, BMP) are upstream signals which regulate the OPG/ OPG-L ratio. •When the balance favors OPG, there are fewer active osteoclasts; when the balance favors OPG-L, there is an increased number of active osteoclasts. RECEPTOR ACTIVATION Osteoclasts also express integrin receptors including the vitronectin receptor which leads to adhesion of osteoclasts to bone surface. Peptides containing the RGD motif have been shown to inhibit osteoclast-mediated bone resorption www.indiandentalacademy.com
  15. 15. Structural composition of bone www.indiandentalacademy.com
  16. 16. Organic Matrix Organic matrix consists of 90% of collagen and remaining 10% is composed of other non-collagenous molecules. Bone Collagen Collagen is defined as a molecule composed of three polypeptide chains termed α chains which associate into a triple helical molecule. Bone consists predominantly of type I collagen with traces of type III, V & XI collagen. Non-collagenous proteins Proteoglycan & Glycoproteins Osteonectins RGD containing proteins (Arg – Gly – ASP) Fibronectin, Thrombospondin, Osteopontin, Bone Sialo Protein. Fibronectin Thrombospondin Osteopontin Bone sialo protein Bone acidic glycoprotein (B A G) Osteocalcin & Matrix Gla Protein Growth Factors Inorganic Component www.indiandentalacademy.com calcium hydroxy apatite - Ca10(PO4)6(OH)2
  17. 17. ORTHODONTIC TOOTH MOVEMENT PEIZOELECTRIC THEORY Bone responds to an applied strain. Strain represents a change in length. Application of small bending forces result in compression on one side and tension on the opposite side. This produces a flow of interstitial fluid, through the canalicular network, generating streaming potentials. Because of the negative charge of proteoglycans, there is an excess of positive mobile ions in the fluid. Charges are symmetrically arranged so that no net macroscopic electric field is present. Compression of bone produces streaming potentials by the displacement of mobile ions relative to charged proteoglycans en-trapped by collagen. Fluid movement over the cell surface may directly stimulate bone cells because it generates shear stress. www.indiandentalacademy.com
  18. 18. ORTHODONTIC TOOTH MOVEMENT AS RELATED TO BONE DEFORMATION BIOELECTRICITY: First suggested by Farrar (1888) Piezoelectricity is a phenomenon observed in many crystalline materials in which deformations of the crystalline materials results in the flow of electric currents. Collagen itself is piezoelectric. Piezoelectricity signals have two unusual characteristics: A quick decay rate The production of an equivalent signal, opposite in direction, when the force is released. www.indiandentalacademy.com
  19. 19. Zengo et al (1973-74) showed that bending of bone may create negative fields occurring in the concave aspects of the bone surface leading to bone deposition and positive fields occuring on the convex bone surface leading to bone resorption Baumrind and Buck et al suggested that the major physiologic and mechanical changes might occur not in the periodontal ligament but rather in the alveolar bone. A second type of endogenous electric signal, which is called the “bioelectric potential” can be observed in bone that is not being stressed. Electronegative charges are observed in areas of metabolically active bone or connective tissue where bone growth or remodeling is occurring. Inactive cells and areas are nearly electrically neutral. The purpose of this bioelectric potential is not yet known. Davidovitch showed that modifying the bioelectric potential, a tooth moves faster than its control. www.indiandentalacademy.com
  20. 20. ORTHODONTIC TOOTH MOVEMENT The orthodontic response is divided into three elements of tooth displacement: initial strain, lag phase, and progressive tooth movement. Initial strain of 0.4 to 0.9 mm occurs in about 1 week because of PDL displacement (strain), bone strain, and extrusion . www.indiandentalacademy.com
  21. 21. PRESSURE TENSION THEORY CHANGES IN THE PERIODONTAL LIGAMENT Progressive displacement of the tooth relative to its osseous support stops in about 1 week, of PDL necrosis. This lag phase lasts 2 to 3 weeks but may be as long as 10 weeks. After undermining resorption restores vitality to the necrotic areas of the PDL, tooth movement enters the secondary, or progres­sive, tooth movement phase. The mechanism of sustained tooth movement is a coordinated array of bone resorption and formation events. www.indiandentalacademy.com
  22. 22. CHANGES IN THE ALVEOLAR BONE Modeling, a change in shape or size of an osseous structure, is achieved by differential bone formation and resorption along the periosteal and endosteal surfaces. Internal turnover of osseous tissue is termed remodeling The remodeling process has evolved a vascularized multicellular unit for removing and replacing cortical bone which is called a cutting/filling cone. Cutting cones create resorption cavities in the cortical bone thereby reducing the density of cortical bone www.indiandentalacademy.com
  23. 23. Remodeling of dense alveolar bone may enhance the rate of tooth movement and replace the less mature osseous tissue formed by rapid PDL osteogenesis. These intraosseous resorption cavities are the initial remodeling events that occur during the first month of the remodeling cycle. www.indiandentalacademy.com
  24. 24. CELLULAR EVENTS  The activation of osteoclast may occur because of the integrins on osteoclast cell membrane with proteins in bone matrix which contain R G D amino acid sequences such as Osteopontin. Has a dual function of allowing osteoclastic access to mineralized bone matrix and releasing factors from the matrix such as osteocalcin which are chemotactic for osteoclasts or their precursors. www.indiandentalacademy.com
  25. 25. How do osteoclasts work? The ruffled border area carries out the resorption process itself.. Osteoclasts contain large amounts of carbonic anhydrase to facilitate the conversion of CO2 and H2O to H2CO3. The degradation of bone matrix is presumably the result of the activity of a number of lysosomal enzymes which can degrade bone at low pH. There is a correlation between activation of bone resorption and acid phosphatase release. A variety of cathepsins and other lytic enzymes which are produced by the osteoclast are able to degrade collagen at low pH. There is a evidence that oxygen­derived free radicals are produced by osteoclasts and may be localized in the ruffled border area. Superoxide dismutase,, has been identified in osteoclasts. www.indiandentalacademy.com OCL - Osteoclast
  26. 26. Reversal The reversal phase lasts from 7 to 14 days The resorption bays are now devoid of osteoclasts and are occupied by Osteocytes, macrophage like mononuclear cells and preosteoblast.. Osteoblasts are summoned into the reversal lacuna.by growth factors www.indiandentalacademy.com
  27. 27. Bone matrix formation Begins with the deposition by the osteoblasts of osteoid,. The second stage in bone formation is mineralization of the organic matrix,). The completed piece of new bone is termed either a basic structural unit or a bone structural unit (BSU). www.indiandentalacademy.com
  28. 28. Bone mineralisation 2 mechanisms. A) Matrix Vesicle :The matrix vesicle contains alkaline phosphatase, pyro­ phosphates, Ca­ATPase, metallo proteinases, proteoglycan and anionic phospholipids which are able to bind to calcium and inorganic phosphate www.indiandentalacademy.com
  29. 29. B) Heterogeneous Nucleation : Non­collagenous proteins act as nucleators and others may act to control crystal growth. Dephosphorylation of the phosphoprotein provides the additional phosphate ions for nucleation and crystal growth. Additional crystallites may form by secondary nucleation from mineral phase particles Factors influencing mineralization Local Factors Collagen – Collagen has holes and pores in which nucleation, crystal growth, secondary nucleation and multiplication of the solid phase can occur. www.indiandentalacademy.com
  30. 30. Non Collagenous Molecules Name Osteopontin Osteonectin Bone Sialo Protein GLA Protein Composition Phosphoprotein Phosphoprotein Phosphorylated glycoprotein Protein & r­carboxy glutamic acid Possible Function inhibits crystal growth inhibits crystal growth nucleator for mineralization Biglycan & Decorin Chondroitan Sulfate Proteo glycans Removed at mineralization front to permit mineralization Phospholipids calcium binding at mineralization front. Pyrophosphate inhibitor of calcification Regulator of crystal growth www.indiandentalacademy.com
  31. 31. Growth Factors FGF : IGF : TGF, PGDF : Interleukin 1 : Tumor necrosis factor: Increase osteo blastic precursor population and also increase collagen synthesis. Increase bone cell proliferation and total protein synthesis. increase proliferation of osteo-progenitor and total protein synthesis. At low doses, it stimulates collagen synthesis but is inhibitor in higher concentrations. stimulate proliferation and collagen synthesis in preosteoblasts. www.indiandentalacademy.com
  32. 32. Systemic Factors PTH, 1,25 - Dihydroxy Vitamin D3, estrogen Role of alkaline phosphates hydrolyzes phosphate ions from organic radical at an alkaline pH Marker of osteoblast activity. Incremental lines Due to variations in the degree of mineralization at the boundaries between periods of activity and rest. www.indiandentalacademy.com
  33. 33. HISTOLOGICAL ASPECT  Primary compacta is formed by woven bone which fills in with lamellar bone to form primary osteons. Within weeks, the new primary bone is remodeled to more mature secondary osteons by a progressive wave of cutting/filling cones . . Supporting bone continues to adapt to the new position of the tooth for up to a year after the end of active tooth movement.  Cortical bone is formed along periosteal and PDL/bone surfaces by the same mechanism. During the retention period the newly formed bone remodels and matures.. www.indiandentalacademy.com
  34. 34. SUTURES The osteogenic layer of the suture is called the cambium, and the inner leaf the capsule. Between these two layers is a loose cellular and vascular tissue. Sutures experience, absorb, and transmit mechanical stresses generated from either functional activities such as mastication, or exogenous forces such as orthopedic loading. Mechanical stresses transmitted through the bone are experienced as tissue level bone strain, interstitial fluid flow that in turn induces cell level strain on the bone cells and subsequent anabolic or catabolic responses , resulting in regional acceleration of bone adaptive activity www.indiandentalacademy.com
  35. 35. Rapid palatal expansion.- the adjacent expanded suture experienced hemorrhage, necrosis, and a wound healing response. Chang et al demonstrated the angiogenic capillary-budding process associated with the propagation of perivascular osteogenic cells www.indiandentalacademy.com
  36. 36. Functional appliances exert the skeletal effect by inducing the action of masticatory muscles expressed by multiple lines of stresses exerted by the masticatory muscle attachment . Sutural expansion within physiologic limits is a clinically viable means of repositioning the bones of the craniofacial complex to improve esthetics and function. www.indiandentalacademy.com
  37. 37. Factors Regulating Tooth movement  Growth;  Bone density  Type of tooth movement  Role of Periodontium  Duration and force magnitude  Circadian rhythm  Effect of chemicals www.indiandentalacademy.com
  38. 38. Parathyroid hormone effects on bone resorption effects on bone formation effects on Ca++ homeostasis Calcitonin short term regulator of Ca++ homeostasis inhibits osteoclastic bone resorption 1,25 - Dihydroxyvitamin D3 Calcium homeostasis bone remodeling - bone resorption www.indiandentalacademy.com
  39. 39. Prostaglandins bidirectional effect on osteoclasts - an immediate transient effect to slow bone resorption and a sustained effect to Osteoclastic bone resorption. Interleukin - 1 - powerful and potent stimulator of bone resorption Tumor necrosis factor - Osteoclastic bone resorption Osteoprotegrin - inhibitor of bone resorption Interleukin - 6 Gamma interferon Growth factors www.indiandentalacademy.com
  40. 40. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com
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