This document discusses the biology of tooth movement during orthodontic treatment. It covers topics such as the periodontal ligament, types of forces, phases of tooth movement, and theories of tooth movement. The key points are:
1) Tooth movement occurs through remodeling of the alveolar bone mediated by the periodontal ligament. Light continuous forces produce optimal movement with minimal tissue damage.
2) Tooth movement involves an initial phase of displacement, followed by a lag phase where hyalinized tissue forms, and then a post-lag phase where movement resumes as the hyalinized tissue is removed.
3) Several theories have been proposed to explain the mechanism of tooth movement, including the pressure-tension
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.
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.
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.for more details please visit
www.indiandentalacademy.com
Frankles appliance Is a myofunctional appliance
Functional appliance are removable or fixed appliances that aim to utilize eliminate or guide the forces arising from muscle function,tooth eruption and growth inorder to alter skeletal and dental relationship
Description :
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.for more details please visit
www.indiandentalacademy.com
it explain need for extraction, choice of teeth for extraction, Wilkinson extraction, extraction of permanent teeth without appliance therapy, balance extractions, compensating extractions, additional factor to consider in extraction of teeth.
Tissue reaction in orthodontics /certified fixed orthodontic courses by Indi...Indian dental academy
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
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.for more details please visit
www.indiandentalacademy.com
Frankles appliance Is a myofunctional appliance
Functional appliance are removable or fixed appliances that aim to utilize eliminate or guide the forces arising from muscle function,tooth eruption and growth inorder to alter skeletal and dental relationship
Description :
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.for more details please visit
www.indiandentalacademy.com
it explain need for extraction, choice of teeth for extraction, Wilkinson extraction, extraction of permanent teeth without appliance therapy, balance extractions, compensating extractions, additional factor to consider in extraction of teeth.
Tissue reaction in orthodontics /certified fixed orthodontic courses by Indi...Indian dental academy
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
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.for more details please visit
www.indiandentalacademy.com
Bone physiologynew /certified fixed orthodontic courses by Indian dental acad...Indian dental academy
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
Biology of tooth movement /certified fixed orthodontic courses by Indian dent...Indian dental academy
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
This content consists of the Periodontal Ligament, Cementum and the Alveolar Bone discriptions. You can also find many content related captions over here. Thanks
Physiology of tooth movement 1 /certified fixed orthodontic courses by Indian...Indian dental academy
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
orthodontic biology of tooth and supporting structure.docxDr.Mohammed Alruby
The goal is to examine the relationship between orthodontic biomechanics and the underlying biological process
When orthodontic force is applied to the crown of the tooth it is transmitted through the roots to the periodontal ligament and alveolar bone
Histology of supporting structure:
- Periodontal ligament
- Alveolar bone
I- Periodontal ligament:
A- Cellular component:
• Forming cells:
Osteoblast: bone forming cells
Fibroblast: PDL fibers forming cells
Cementoblast: in layer adjacent to the roots
• Resorptive cells:
Osteoblast: large cell rich acid phosphatase enzyme that demineralize the bone and disintegrate of organic matrix
Fibroblast: disintegrate fibers
Cementoblast: resorb cementum
• Progenitor cells: undifferentiated mesenchymal cells UMC: small cells with closed nucleus and little cytoplasm & monocytes
• Epithelial rest of malassez: arise as a result of breakdown of epithelial root sheath at the time of cementogesis
• Defensive cells: as macrophages & mast cells
B- Periodontal fibers:
1- Collagen fibers:
the main bulk of PDL fibers and found in 5 groups:
- Alveolar crest group: from cervix to alveolar crest
- Horizontal group: from cementum to bone horizontally
- Oblique group: the main attachment that run obliquely from cementum to bone in an apical direction
- Apical group: circumscribed the apex and responsible for resistance to rotation
- Inter-radicular group: inter-mediate plexus, observed midway between bone and root
- Supra-alveolar group:
Dento-gingival
Dento-periosteal
Transeptal
Circular
Alveolo-gingival
2- Oxytalan fibers:
Immediate elastic fibers that resist dissolution by acids unlike collagen
Run from cementum or bone to blood vessels
Play a role in supporting the blood vessels against distortion and compressive strain
c- Ground substances:
organic matrix surrounding the PDL elements, it is chemically composed of CHO linked with protein. CHO- protein complex commonly divided into two groups: proteoglycan and glycoprotein
ground substances of periodontal ligament is in a continuous state of remodeling process
d- Neurovascular elements:
myelinated: pain sensation
non-myelinated: blood vessels wall
PDL functions:
- Supportive
- Nutritive
- Remodeling
- Sensory
II- Alveolar bone:
= in human, marrow spaces are rare in the buccal and lingual plates, these spaces decreased with age
= wider spaces are lined with a layer of fenestrated compact bone when PDL fibers are anchor these fibers is called bundle bone
N: B:
= collagen turn over in PDL is higher 4 times than skin and 2 times than gingiva and this due to the forces in PDL is multi-directional takes vertical and horizontal component
= lake of marrow spaces implies that bone resorption takes more time so that the tooth movement in mesial and distal direction occur more than labial and lingual sides
= the resorptive cells increase as the marrow spaces increase
N: B:
The new deposited tissue during tooth migration have 3 stages:
Stage I osteoid:
is the pr
orthodontic biology of tooth and supporting structure.docxDr.Mohammed Alruby
Histology of supporting structure
- Periodontal ligament
- Alveolar bone
= types of tooth movement
= classification of force during treatment
= factors affect tooth movement
= hyalinization
= types of root resorption
= factors affect tooth movement according to pressure tension theory
= role of chemical mediators in tooth movement
= role of neurotransmitter in tooth movements
Orthodontics-Periodontics Relationship
ntroduction
Biological basis for orthodontic therapy
Periodontal tissue response to orthodontic force
Effects of orthodontic tooth movement on the periodontium
Orthodontic tooth movement in adults with periodontal tissue breakdown
Specific factors associated with orthodontic tooth movement
Implants and orthodontic therapy
Systematics of combined ortho – perio treatment
Periodontally Accelerated Osteogenic Orthodontics (PAOO)
Minor periodontal surgery and orthodontic treatment
Review of literature
Introduction
Histology of supporting structure
Types of tooth movements
Phases of orthodontic tooth movements
Biological changes by tooth movements
Theories of tissue reactions
Replacement resorption
Biology of bone in complete dentures, removable partial denture, overdenturePiyaliBhattacharya10
describes the biology of bone in physiologic condition, about bone remodeling, bone resorption in complete denture, combination syndrome, bone resorption in immediate denture and overdenture
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
1. By Dr. Arti Kripalani
Part I P.G.
K.M.Shah Dental College
2. Introduction
Periodontal ligament
Physiologic tooth movement
Optimum orthodontic force
Types of forces
Histology of tooth movement
Hyalinization
Phases of tooth movement
Theories of tooth movement
3. Orthodontic treatment is based on the principle that if
prolonged pressure is applied to a tooth, tooth
movement will occur as the bone around the tooth
remodels.
Bone is selectively removed in some areas and added
in others.
4. The tooth moves through the bone carrying its
attachment apparatus with it, as the socket of the tooth
migrates.
Because the bony response is mediated by the
periodontal ligament, tooth movement is primarily a
periodontal ligament phenomenon.
5.
6. During masticatory function, the teeth
and periodontal structures are subjected
to intermittent heavy forces.
Tooth contacts last for 1 second or less.
Forces are quite heavy, ranging from 1 or 2 kg while soft
substance are chewed up to as much as 50 kg against a
more resistant object.
7.
8. Naturally occurring tooth movements that take place
during and after tooth eruption.
This include:
A)Tooth Eruption.
B)Migration or drift of teeth.
C)Changes in tooth position during mastication.
9. Tooth eruption is the axial movement of tooth from its
developmental position in the jaw to its final position
in the oral cavity.
10. a)Blood pressure theory:
The tissue around the developing end of the root is highly
vascular.
This vascular pressure is believed to cause the axial
movement of teeth.
b)Root Growth:
The apical growth of roots result in an axially directed
force that brings about the eruption of teeth.
This theory was rejected.
c)Periodontal traction theory:
The periodontal ligament is rich in fibroblasts that contain
contractile tissue.
The contraction of these periodontal fibers (mainly the
oblique group of fibers) results in axial movement of the
tooth.
11. d)Hammock ligament theory:
According to Sicher, a band of fibrous tissue exists below
the root apex spanning from one side of alveolar wall to
other.
This fibrous tissue appears to form a network below the
developing root and is rich in fluid droplets.
The developing root forces itself against this band of
tissue, which in turn applies an occlusally directed force on
tooth.
12. Refers to minor changes in tooth position observed
after eruption.
Human dentition shows a natural tendency to move in
a mesial & occlusal direction.
Usually a result of proximal and occlusal wear of teeth,
to maintain inter-proximal and occlusal contact.
This was pointed out for the first time by Stein and
Weinmann.
13. Physiologic tooth migration usually is related to mesiodistal
movements. However, the teeth also exhibit a continued
eruption, even after full emergence, accompanying the
growth in height of the alveolar processes.
Studies of craniofacial dimensions have demonstrated that
significant changes occur in human beings even during
adulthood (Bjork A, Skieller V, 1983).
14. During mastication ,the teeth and PDL structures are
subjected to intermittent heavy forces which occurs in
cycles of one second or less and may range from 1-50
kg based on the type of food being masticated.
15. Is one which moves teeth most rapidly in the desired
direction ,with the least possible damage to tissue and
with minimum patient discomfort.
Schwarz defined it as the force leading to a change in
tissue pressure ,that approximated the capillary vessel
& blood pressure. Thus preventing their occlusion in
the compressed PDL.
16. Below the optimal level cause no reaction in PDL.
Forces exceeding optimal level would lead to areas of
tissue necrosis.
17. Schwarz’s definition was slightly modified by
Oppenheim who advocated the use of lightest force
capable of bringing about tooth movement.
Oppenheim and Schwarz following extensive studies
stated that the optimum force is equivalent to the
capillary pulse pressure which is 20-25 gm/sq.cm of
root surface area.
18. Produce rapid tooth movement.
Minimal patient discomfort.
The lag phase of tooth movement is minimal.
No marked mobility of the teeth being moved.
19. The vitality of the tooth and supporting PDL is
maintained.
Initiates maximum cellular response.
Produces direct or frontal resorption.
20. Continuous force : the force magnitude
is maintained at almost the same level
in the period between two activations.
Interrupted force : declines to zero
between activations.
Intermittent force : falls to zero when
the appliance is removed and return to
original level on re insertion.
21. Classic histologic research about tooth movement by
Sandstedt, Oppenheim and Schwarz led to the
hypothesis that a tooth moves in the periodontal space
by generating a ‘pressure side’ and a ‘tension side.’
Later ultrastructural studies by Rygh (1972) and
Brudvik and Rygh (1994), gave a very detailed
description of events.
The findings of the above research have been
meticulously summarized by Krishnan and
Davidovitch (2006).
22. Changes following application of light forces:
Changes on pressure side:
The PDL gets compressed to almost 1/3rd of it’s original
thickness.
A marked increase in the vascularity of PDL on this side is
observed due to increase in capillary blood supply.
This increase in blood supply helps in mobilization of cells
such as fibroblasts and osteoclasts.
When forces applied are within physiologic limits,the
resorption is seen in alveolar plate immediately adjacent to the
ligament.This kind of resorption is called frontal resorption.
23. Changes on tension side:
PDL stretched.
Distance between alveolar process & tooth is widened.
Increased vascularity.
Mobilization of fibroblasts & osteoblasts.
Osteoid is laid down by osteoblast in PDL immediately
adjacent to lamina dura.
Lightly calcified bone mature to form woven bone.
24. Secondary remodelling changes:
Bony changes also takes place elsewhere to maintain the width
or thickness of alveolar bone. These changes are called
secondary remodeling changes.
For eg:-If a tooth is being moved in a lingual direction there is
compensatory deposition of new bone on the outerside of the
lingual alveolar bony plate and also a compensatory resorption
on the labial side of the labial alveolar bone.
This is to maintain the thickness of the supporting alveolar
process .
25. On the pressure side :-
Root closely approximates the lamina dura .
Compresses the PDL and leads to occlusion of blood vessels.
The PDL is hence deprived of its nutritional supply leading to
regressive changes called hyalinization .
Undermining/Rearward resorption occurs in the adjacent
marrow spaces and alveolar plate below, behind & above the
hyalinized zone.
26. On the tension side:-
Over stretched PDL .
Tearing of blood vessels & ischaemia.
Extreme forces applied net increase in osteoclastic activity
and tooth loosened in socket.
27.
28. Is orthodontic movement possible for a tooth that has
undergone endodontic treatment ?
Is it possible to move an ankylosed tooth ?
29. Form of tissue degeneration characterized by formation
of a clear, eosinophilic homogenous substance.
Denotes a compressed and locally degenerated PDL.
Reversible process.
Occurs in almost all forms of orthodontic tooth
movement but the areas are wider when the force
applied is extreme.
30. Gradual shrinkage of PDL fibres.
Cellular structures become indistinct.
Collagenous tissues gradually unite
into a more or less cell free mass.
break down of blood vessel walls
leading to spilling of their contents.
Osteoclasts are formed after a period
of 20-30 hrs.
31. The presence of hyalinised zone indicates that the
ligament is non-functional and therefore bone
resorption cannot occur.
The tooth is hence not capable of further movement
until the local damaged tissue has been removed and
the adjacent alveolar bone resorbs .
32. 2 mechanism:-
1. By osteoclasts differentiating in the peripheral intact
PDL membrane and in the adjacent marrow spaces.
2. Invasion of cells and blood vessels from the
periphery of the compressed zone by which necrotic
tissue is removed by enzymatic action and
phagocytosis
33. Greater the forces wider is the area of hyalinization.
Thus larger areas of the ligament becomes
functionless, thereby showing larger areas of rearward
resorption.
If lighter forces are used, the hyalinised zone is
smaller and a larger area of functioning ligament is
available and frontal resorption predominates.
The location and extent of hyalinised tissue largely
depends upon nature of tooth movement.
34. Tipping – close to alveolar crest.
Excessive force during tipping- two areas, one on
apical region and other in marginal area.
Bodily- closer to middle portion of root.
35. Authors: Journal: Level of
evidence:
Aim and
objectives:
Result and Conclusion:
S. H.
Jónsdóttir,
E. B. W.
Giesen and
J. C. Maltha
EJO 2012 4 To study and assess
the biomechanical
behaviour of the
hyalinized
periodontal ligament
in experimental
orthodontic tooth
movement
A rapid transposition
during the first few
seconds was found.
However, it was
significantly less for
hyalinized than for non-
hyalinized PDL.
The hyalinized tissue
offers resistance to tooth
movement and it is
proportional to the
degree of hyalinization.
37. Rapid tooth movement is observed over a short distance which
then stops.
Represents displacement of tooth in PDL membrane space and
probably bending of alveolar bone .
Both light and heavy forces displace the tooth to same extent .
Between 0.4 to 0.9mm usually occurs in a weeks time.
38. Little or no tooth movement occurs .
Formation of hyalinized tissue .
Extent upto 2-3 weeks but may at times be as long as
10 weeks.
39. Tooth movement progresses rapidly as the hyalinized
zone is removed and bone undergoes resorption .
Osteoclasts are found over a larger surface area.
40. If the duration of the movement is divided into an initial and a
secondary period, direct bone resorption is found in the secondary
period, when the hyalinized tissue has disappeared after
undermining bone resorption.
41. Study by Pilon et al performed on beagles,
divided the curve of tooth movement into 4 phases:
The first phase lasts 24 hrs to 2 days and represents the
initial movement of the tooth inside its bony socket.
Second phase when the tooth movement stops for 20 to 30
days.
After the removal of necrotic tissue formed during the
second phase , tooth movement is accelerated in the third
phase and continues into the fourth linear phase.
42. 1. The pressure-tension theory
2. Bone bending & piezoelectric theory
3. Blood flow/fluid dynamic theory
43. Classic histologic research about tooth movement by
Sandsted (1904),Oppenheim (1911) and Schwarz
(1932) led them to hypothesize that a tooth moves in
the periodontal space by generating a “pressure side”
and a “tension side.”
According to them, areas of pressure show bone
resorption while areas of tension show bone
deposition.
44.
45. Farrar was the first to suggest, in 1888, that alveolar
bone bending plays a pivotal role in orthodontic tooth
movement.
This hypothesis was later confirmed with the
experiments of Baumrind in rats and Grimm in
humans.
46. Piezo-electricity is a phenomenon observed in many
crystalline materials in which deformation of the
crystal structure produces a flow of electric current.
As a result, displacement of electrons from one part of
the crystal lattice to the other.
A small electric current is generated & bone is
mechanically regenerated and repaired.
47. The possible source of electric current are :-
1. Collagen.
2. Hydroxyapetite.
3. Collagen hydroxyapetite interface.
4. Mucopolysaccharide.
48. As long as the force is maintained ,the crystal structure is
stable & no further electric effect is observed.
When the force is released the crystals return to their
original shape & reverse flow of electrons is observed.
This rhythmic activity produces a constant interplay of
electric signals .
49. Quick decay rate
When the force is released electrons flow in the opposite
direction.
On application of a force on a tooth ,
Areas of concavity negative charges bone deposition.
Areas of convexity +ve charges and bone resorption.
50.
51. It was proposed by Bien in 1966.
Acc. to this theory:
“Tooth movement occurs as a result of alterations in fluid
dynamics in the PDL.”
There are three interacting fluid systems in the PDL:
1. Vascular system
2. Cellular system
3. Interstitial fluid system
52. These fluids in confined periodontal space create a unique
hydrodynamic condition.
ORTHODONTIC FORCE
compression of PDL
Occlusion of blood vessels on pressure side
and dilation on tension side
formation of aneurysms
53. Fluid is squeezed out of vessel wall
O2 level falls in compressed area and rises on tension side
metabolite changes take place
change in chemical environment stimulates release of chemical
messengers
They stimulate cellular differentiation into Osteoblasts and Osteoclasts
Bone Remodeling takes place.
57. Cytokines (tumor necrosis factor [TNF], interleukin-1 alpha, 6-alpha
[I]), macrophage colony stimulating factor (M-CSF), granulocyte,
macrophage colony stimulating factor (GM-CSF) and prostaglandin
(PGE2).
Osteoclast differentiation is also mediated by the interaction of
two molecules produced by osteoblasts, namely osteoprotegrin
(OPG) and RANK ligand (RANKL) Receptor activator of nuclear
factor kappa B ligand
58.
59.
60. At the “Biology of tooth movement” conference held at
Formington in Nov.,1986 it was suggested that the ans
was likely to be found in the field of CYTOKINE
biology.
According to this hypothesis,formation and resorption
depends upon:
1) the cytokines
2) the functional state of available target cells.
61. The cytokines are defined as short range soluble
mediators released from cells which modulate the
activity of other cells.
Includes interleukines, interferons, chemotactic
factors,tumor necrotic factors,colony stimulating
factors and assorted growth factors.
62. Q) How do cytokines mediate mechanically induced
bone remodelling ?
A) Osteoblasts have receptors for prostaglandins, PTH,
Vit D but osteoclasts don’t have.
It is cytokine that transmits signals from osteoblasts to
osteoclasts.
Cytokines either activate osteoclasts or promote
differentiation of the precursor cells.
Secondly, osteoblasts produce collagenase enzyme that
resorbs osteoid.
Osteoclasts cannot resorb bone untill the surface
osteoid layer is removed.
63. Although cytokine is a potent stimulator of bone
resorption,it can also stimulate osteoblast proliferation.
Therefore, whether resorption or formation, depends
upon the cytokines and functional state of the available
target cells.
Tooth movement ultimately depends on specific
activation of bone precursor cells ( osteoprogenitors)
which form osteoblasts and osteoclasts.
66. Von Euler (1934) – prostate fluid.
Imp role in stimulating bone resorption.
One of the chief mediators of inflammation cause an
increase in intracellular cAMP and Ca++ accumulation.
68. Davidovitch and Shanfeld,
Davidovitch et al., Yamasaki et al. (first reported
human study, 1982-83),Lee et al., Selinkale et al. and
many others.
Mohammed et al injected PG inhibitor, leukotriene
inhibitor and both together, in rats and performed tooth
movement.
69. substance P
vasoactive intestinal polypeptide (VIP)
calcitonin gene related peptide (CGRP).
Davidovitch et al demonstrated that incubation of
substance P in vitro significantly increased the
concentration of cAMP in the cells and of PGE2 in the
medium within 1 minute.
70.
71. Authors: Journal: Level of
evidence:
Aim and
objectives:
Result and Conclusion:
Davidovitch
et al
Dental clinic of
N.American
1988
4 To test the
hypothesis that
tissue remodeling
during orthodontic
tooth movement is
modulated by factors
derived from the
nervous and vascular
systems.
Administration of SP and
IL-1 beta to human PDL
fibroblasts in vitro for 1 to
60 minutes resulted in
significant increases in the
levels of the intracellular
"second messenger" cAMP,
as well as of PGE2.
This tend to support the
hypothesis that
neurotransmitters and
cytokines play a regulatory
role in orthodontic force-
induced alveolar bone
remodeling.
72. Three distinct isoforms of NOS are:
- a neuronal form (nNOS),
- an endothelial form (eNOS),
- an inducible form (iNOS).
Both nNOS and eNOS are constitutively expressed
and are collectively referred to as constitutive NOS
enzymes (eNOS).
It was found that iNOS plays a role in the
response of periodontal tissue to orthodontic force.
73. 1. NO activates guanylyl cyclase in periodontal
ligament fibroblasts, leading to an increased level of
cGMP. This second messenger in cell cytoplasm raises
lysosome membrane permeability, leading to
exocytosis of lysosome content resulting in resorption
of organic and mineral elements of bone.
2. Nitric oxide synthesizes prostaglandins by direct
activation of cyclo-oxygenase.
3. Nitric oxide influences the function of osteoclastic
differentiation and osteoblast function.
74. 1) strain sensitive ion channels and shear stress receptors
in cell membrane:
calcium and potassium channels.
Channel gating may be caused by direct mechanical
perturbation or secondarily by the activation of stretch
sensitive phospholipase C or D.
They respond to mechanical strain by causing in and
out movement of ions, creating changes in the electric
potential.
These changes enable the signal to be propagated
intracellularly.
76. Sutherland and Rall established the second-messenger
basis for hormone actions in 1958.
They proposed that the first messenger binds to a
specific receptor on the cell membrane and produces an
intracellular chemical second messenger.
This second messenger then interacts with cellular
enzymes which evokes a response.
- cAMP
- cGMP
- IP3
77.
78.
79.
80. The receptor activator of nuclear factor kappa B ligand
(RANKL), its decoy receptor (RANK) and
osteoprotegrin (OPG) were found to play important
roles in regulation of bone metabolism.
Evidences suggest osteoblast itself regulates the
differentiation of osteoclast.
The talk between an osteoblast and osteoclast is
accomplished through an osteoblast membrane bond
RANKL which can interact with osteoclast precursors
to cause them to differentiate into osteoclasts.
Another membrane bond molecule and its bonding
ligand OPG can develop to block RANKL and prevent
osteoclast formation.
81. Extensive studies done by Alhashimi et al., Aihara et
al., Kanzaki et al.,and Yamaguchi et al. have
demonstrated that RANKL promotes osteoclastogenesis
while OPG inhibits this effect.
82.
83. One of the most distinctive features of bone
remodeling of both cortical and trabecular bone is the
precise coupling of bone resorption and formation.
The A-R-F process is similar for all types of bone
remodeling; the multicellular unit for a trabecular bone
surface is essentially a hemisection of the
cutting/filling cone for cortical bone.
84. (1) bone microdamage results in release of inflammatory
cytokines (prostaglandins, interleukin 1-, and so on) and
exposure of mineralized collagen to extracellular fluid.
(2) T cells, attracted by the inflammatory cytokines and
exposed mineralized collagen, produce the ligand RANKL,
which induces osteoclastogenesis
(3) preosteoclasts from circulating blood have RANK
receptors, which are activated by the RANKL to from
osteoclasts
(4) as bone is resorbed, growth factors are released that
stimulate preosteoclasts to produce OPG which then retract
from the bone surface.
85. (5) mononuclear cells move in and coat the scalloped
resorbed surface with cementing substance (green)
(6) perivascular osteogenic cells migrate through the
low cell density zone and differentiate to preosteoblasts
that then divide and form two osteoblasts each.
(7) osteoblasts form new bone, filling the resorption
cavity and completing the turnover process.
86. 1. Effect on the pulp
Heavy intrusive force can sever the blood vessels as they
enter the root apex and that can affect the tooth vitality.
2. Effects on the root structure
Some root remodeling constantly occurs during orthodontic
tooth movement.
But permanent root loss ( root resorption) occurs if:
there are conical roots with pointed apices,
dilacerated / distorted root form,
excessive force over prolonged period,
root apices in contact with cortical bone,
history of trauma.
87. 3. Mobility
PDL usually widens during orthodontic treatment
hence some mobility of teeth is unavoidable during
orthodontic treatment.
Heavy sustained O.F. results into greater amount of
undermining resorption and thereby greater mobility.
If tooth becomes excessively mobile during treatment,
all
forces should be discontinued for time being till
mobility reduces.
88. 4. Pain
Pain during orthodontic treatment occurs due to development
of ischemic areas in the PDL.
Heavier forces will cause more pain.
Upon activation using light forces can also produce pain for
few hours to few days.
This also greatly depends upon individual pain threshold.
If patient is engaged in repeated chewing during initial 8 hrs.
after activation the pain can be reduced.
Excessive pain during activation is an indication of too heavy
force which should be avoided.
89. Orthodontic tooth movement consequent t application
of force is outcome of complex chain of events,
eventually leading to bone resorption and bone
formation.
What signals the ‘cells’ in periodontium to perceive
orthodontic force to transform into bone forming and
bone resorbing cells is not yet fully understood.
Future research in the field of molecular biology is
expected to unfol many more secretes of this
phenomenon.