This seminar contains mostly everything related to the topic mentioned above along with the supporting articles and references.

1. Biology of tooth movement
Guided by :-
Dr. Kamal Bajaj
Prof and HOD
Presented by :-
Dr. Lakshay Mihani
PG 2nd Yr

2. Tooth supporting structures
Orthodontic tooth movement
↓↑
Changes in tooth supporting structures
• Periodontium is a connective tissue organ covered by
epithelium, that attaches the teeth to the bones of the
jaws and provides a continually adapting apparatus for
support of teeth during function

3. • 4 connective tissues of periodontium are:-
• Two fibrous
- Lamina propria of the gingiva.
- Periodontal ligament
• Two mineralized
- Cementum
- Alveolar bone

4. GINGIVA
• Parts of gingiva:
• - Free or marginal gingiva
• -Attached gingiva
• Components:
• -Collagen fibres
• -Fibroblasts
• -Nerves
• -Matrix

5. • Fibres of gingiva:
• Circular
• Dentogingival
• Dentoperiosteal
• Transseptal fibres
(Accesory fibres)

6. Periodontal ligament
• Connective tissue interface separating the tooth
from the supporting bone .
• Heavy collagenous supporting structure- 0.15 to
0.38 mm in width .
• Apart from collagen fibres:
- Cellular elements-mesenchymal,
vascular & neural
- Tissue fluids
• Constant remodeling of fibres, bone &
cementum

7. • Principal fibres:
• 1. Alveolar crest group
• 2. Horizontal group
• 3. Oblique group
• 4. Apical group
• 5. Inter-radicular
• 6. Transseptal group

8. • Cells:
>Proginator cells
>Synthetic cells
- Osteoblasts, Fibroblasts, Cementoblasts
> Resorptive cells
- Osteoclasts, Fibroblasts, Cementoclasts
• Tissue fluid:
>Derived from the vascular system
>Shock absorber-retentive chamber with porous walls

9. 3. Cementum
• Attaches the PDL fibres to the root
• Avascular, no innervation, no remodeling
• Continuous deposition through out life
• Contributes to the process of repair – after
orthodontic tooth movement

10. 4. Alveolar bone
• Forms and support the sockets of the teeth.
• Consists of dense outer cortical bone and
varying amount of cancellous bone between
them.
• Alveolar bone is renewed constantly in response
to functional demands.
• Osteoblasts and osteoclasts are the cells
responsible for bone remodelling.

11. PDL Response to normal function
• 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.

13. Physiologic Tooth Movement
• 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.

14. A :Tooth Eruption
• Tooth eruption is the axial movement of tooth
from its developmental position in the jaw to its
final position in the oral cavity.

15. Theories of tooth eruption
• 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.

16. • 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.

17. • 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.

18. B: Migration or drift of teeth
• 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.

19. • 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).

20. C: Tooth movement during mastication
• 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.

21. Role of PDL in eruption and
stabilization of teeth

22. Optimum orthodontic force
• 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.

23. • Below the optimal level cause no reaction in
PDL.
• Forces exceeding optimal level would lead to
areas of tissue necrosis.

24. • 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.

25. From clinical point of view Optimum
orthodontic force should have
following characteristics :-
• Produce rapid tooth movement.
• Minimal patient discomfort.
• The lag phase of tooth movement is minimal.
• No marked mobility of the teeth being moved.

26. From histologic point of view
Optimum orthodontic force should
have following characteristics :-
• The vitality of the tooth and supporting PDL is
maintained.
• Initiates maximum cellular response.
• Produces direct or frontal resorption

27. Types of forces :-
• 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.

29. Reaction of teeth to different type of
forces
• TIPPING :-

30. • TRANSLATION:-

31. • ROTATION:-

32. • INTRUSION:-

33. Optimum forces for orthodontic tooth
movement

34. Effect of force magnitude :-

36. Phases of tooth movement
• Burstone categorize the stages as:-
• Initial phase
• Lag phase
• Post lag phase

38. Initial phase :-
• 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.

39. Lag phase :-
• 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.

40. Post Lag phase :-
• Tooth movement progresses rapidly as the
hyalinized zone is removed and bone undergoes
resorption .
• Osteoclasts are found over a larger surface area.

41. • 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.

42. • 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.

43. Histology of tooth movement :-
• 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).

44. • 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.

46. • 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.

47. • Secondary remodelling changes:

48. • 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 .

49. Changes following application of heavy
forces :-
• 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.

50. • 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.

52. Hyalinization
• 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.

53. Changes observed during formation of
hyalinized zone are :-
• 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.

55. • 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 .

56. Elimination of hyalinised tissue :-
• 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

57. Theories of tooth movement
• 1. The pressure-tension theory
• 2. Bone bending & piezoelectric theory
• 3. Blood flow/fluid dynamic theory

58. Blood flow/fluid dynamic theory
• 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

59. • These fluids in confined periodontal space create
a unique hydrodynamic condition.

60. • ORTHODONTIC FORCE
• compression of PDL
• Occlusion of blood vessels on pressure side
and dilation on tension side
• formation of aneurysms
• Fluid is squeezed out of vessel wall

61. • 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.

62. Bone bending & piezoelectric theory
• 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.

63. • 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.

64. • The possible source of electric current are :-
1. Collagen.
2. Hydroxyapetite.
3. Collagen hydroxyapetite interface.
4. Mucopolysaccharide.

65. • 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 .

66. Piezoelectric signal have two unusual
characteristics :-
1. Quick decay rate
2. When the force is released electrons flow in
the opposite direction.

67. • On application of a force on a tooth ,
• Areas of concavity negative charges bone
deposition.
• Areas of convexity +ve charges and bone
resorption.

68. Classic theory / Pressure-tension
theory
• The pressure-tension theory, the classic theory
of tooth movement, relies on chemical rather
than electric signals as the stimulus for cellular
differentiation and ultimately tooth movement.
• According to them, areas of pressure show bone
resorption while areas of tension show bone
deposition.

69. • In essence this view of tooth movement shows
three stages:
• ( 1) alterations in blood flow associated with
pressure within the PDL,
• (2) the formation and release of chemical
messengers and
• (3) activation of cells

71. On tension side
• Widening of the PDL is observed. In the
stretched PDL, several cellular processes are
apparently activated, along with an increase in
the number of connective tissue cells and
increased vascularity. Beyond a certain level of
stress, the vascular supply to the PDL decreases,
with cell death occurring between stretched
fibres.

72. • The blood vessels in the PDL on the tension site
become distended and there is cellular
infiltration of the tissue by macrophages and
leucocytes along with proteins and fluids, which
migrate from the adjacent PDL capillaries and
evoke an inflammatory response.

73. • Fibroblasts are rearranged in the direction of
strain. These fibroblasts secrete new Sharpey’s
fibers in the PDL and part of these newly
synthesized collagen fibers are incorporated in
the newly formed osteoid, whereas the other part
is embedded in the PDL simultaneously with the
deposition of a new matrix on the adjacent
alveolar bone socket wall.

74. On the pressure side
• • There is narrowing of the PDL space and
deformation of the alveolar crest bone.
Depending upon the magnitude of applied force,
the reaction at this site differs; light pressure
produces direct bone resorption and heavy
forces produce hyalinization.

75. • Changes in the compressed PDL are
characterized by oedema, gradual obliteration of
blood vessels, and breakdown of the walls of
veins, followed by leakage of blood constituents
into the extravascular space.

76. • • Changes seen in fibroblasts at these sites are
moderate swellings of the endoplasmic
reticulum, formation of vacuoles, rupture and
loss of cytoplasm. This disintegration leaves
isolated nuclei, which undergo lysis over a
period of several weeks and the retained ground
substance gives a glossy appearance.
Accumulated erythrocyte breakdown products in
pressure regions might undergo crystallization.

77. • No tooth movement occurs until the necrotic
tissue is removed by the invasion of
phagocytosing cells from peripheral undamaged
ligament and bone marrow spaces. This removal
is completed after 3 to 5 weeks, and the post
hyalinized PDL is markedly wider than before
treatment, perhaps to withstand greater
mechanical influences’.

78. Chemical messengers :-
• Messengers are chemicals that transmit
messages from one place to another.
• It can be hormones, neurotransmitters or
vasoactive peptides .

79. 1st messenger :-
-PG E plays a major role in cell differentiation.
- Acts as 1st messenger.
- Its role is to activate extracellular signals.
- Other 1st messengers are :-
PTH
Substance P
Vasoactive peptides

80. 2nd messenger :-
• Next step is conversion of extracellular signals to
intracellular signals and increases cellular
concentration.
• It takes place by 2 pathways :-
*The cyclic nycleotide pathway
*The phosphatidyl inositol dual signal system
• cAMP and cGMP are two important 2nd
messenger .

81. 3rd messenger
• Protien kinase enzyme is the 3rd messenger.
• Protien kinase enzyme along with cAMP-
dependent enzyme cause phosphorylation of the
cells and subsequent differentiation and
activation of osteoclasts and osteoblasts to
produce remodelling.

82. Pathways of tooth movement

83. Methods for accelerated tooth
movement :-
1. Biological approach
2. Physical/ deviced assisted/mechanical
approach
3. Surgical approach

84. Biological approach :-
• Drugs/Hormones Increasing orthodontic tooth movement are
:-
• VIT D
• PTH
• Thyroid
• Corticosteroids
• Prostaglandins
Watted N et al: Influence of drugs on orthodontic tooth movement :Journal of Research
in Medical and Dental Science | Vol. 2 | Issue 4 | October –December 2014

85. • Drugs/Hormones decreasing orthodontic tooth movement are :-
• NSAIDS
• Aspirin
• Indomethacin
• Diclofenac
• Ibuprofen
• Fluoride
• Bisphosphonates
• Estrogen
• Calcitonin
• Cyclosporin A
• Leusulfan
• Valproic acid
• Gabapentin
• Phenytoin
Watted N et al: Influence of drugs on orthodontic tooth movement :Journal of Research
in Medical and Dental Science | Vol. 2 | Issue 4 | October –December 2014

86. Physical/ deviced assisted/mechanical
approach
BIOLUX
DEVICE

87. Acceledent

88. Vibratory stimulation increases interleukin-1
beta secretion during orthodontic tooth movement.
Angle Orthod. 2016 Jan;86(1):74-80.
• They investigated the effects of application of
vibratory stimuli on interleukin (IL)-1β secretion
during maxillary canine distalization.
• They studied split-mouth design in 15 subjects
(mean age, 22.9 years; range 19-25 years) whose
bilateral maxillary first premolars were extracted
with subsequent canine distalization.

89. • On the experimental side, light force (60 g) was
applied to the canine for 3 months in
combination with vibratory stimuli provided
using an electric toothbrush 15 minutes a day for
2 months; only orthodontic force was applied to
the contralateral control canine.

90. • Gingival crevicular fluid (GCF) was collected
from the mesial and distal sides of each canine at
each monthly appointment. They concluded
that, in combination with light orthodontic
force, application of vibratory stimuli using an
electric toothbrush enhanced the secretion of IL-
1β in GCF and accelerated orthodontic tooth
movement.

91. Low-level laser therapy increases interleukin-1β in
gingival crevicular fluid and enhances the rate of
orthodontic tooth movement.
Varella AM, Revankar AV, Patil AK.Am J Orthod Dentofacial Orthop. 2018
Oct;154(4):535-544
• The aim of this investigation was to evaluate the
effects of low-level laser therapy on interleukin-
1β (IL-1β) levels in gingival crevicular fluid and
its correlation with orthodontic tooth
movement.

92. • A split-mouth design was used in 10 subjects (6
female, 4 male) aged 14 to 25 years, whose
maxillary first premolars were extracted.
• A gallium-aluminum-arsenide semiconductor
diode laser (wavelength, 940 nm; energy
density, 8 J/cm2; power output, 100 mW)
delivered low-level laser therapy to the
experimental canine undergoing distalization at
10 points.

93. • The control canine was distalized without low-level
laser therapy. The experimental and control canines
were distalized using a force of 150 g provided by
nickel-titanium closed-coil springs.
• Gingival crevicular fluid was collected at 5 time
points from the control and experimental sides, and
the levels of IL-1β were analyzed by enzyme-linked
immuno-sorbent assay (ELISA). The distal
movements of the maxillary canines were measured
and compared.

94. • Increased levels of IL-1β were observed in the
experimental canines compared with the control
canines
• Cumulative tooth movements over an 8-week
experimental period were greater for the
experimental canines (occlusogram and software,
4.450 and 4.4903 mm, respectively) compared with
the control canines (occlusogram and software,
2.025 and 2.0501 mm, respectively).

95. Surgical Approach
• DISTRACTION OSTEOGENESIS
• CORTICOTOMY
• MODIFIED CORTICOTOMY
• MICRO-OSTEOPERFORATIONS

96. Distraction osteogenesis

97. Moving an Ankylosed Central Incisor Using Orthodontics,Surgery and
Distraction Osteogenesis; Angle Orthodontist, Vol 71, No 5,
2001ISAACSON, STRAUSS, BRIDGES-POQUIS, PELUSO, LINDAUER

100. Corticotomy

101. Modified corticotomy

102. MICRO-OSTEOPERFORATIONS
The device Propel

105. Effect of micro-osteoperforations on the rate of tooth movement;
ManiAlikhani; MarkosRaptis; BillieZoldan American Journal of
Orthodontics and Dentofacial Orthopedics, Volume 145, Issue 3, March
2014, Pages 273
• Twenty adults with Class II Division 1 malocclusion
were divided into control and experimental groups.
The control group did not receive micro-
osteoperforations, and the experimental group
received micro-osteoperforations on 1 side of the
maxilla. Both maxillary canines were retracted, and
movement was measured after 28 days. The activity
of inflammatory markers was measured in gingival
crevicular fluid using an antibody-based protein
assay. Pain and discomfort were monitored with a
numeric rating scale.

106. • Micro-osteoperforations significantly increased the
rate of tooth movement by 2.3-fold; this was
accompanied by a significant increase in the levels of
inflammatory markers. The patients did not report
significant pain or discomfort during or after the
procedure, or any other complications.
• Micro-osteoperforation is an effective, comfortable,
and safe procedure to accelerate tooth movement
and significantly reduce the duration of orthodontic
treatment.

107. References:-
• Graber, Vanarsdall, Vig;Orthodontics current
principles and techniques;fifth edition; 2012
• Proffit W.R ; Fields H.W; Sarver D.M;
Contemporary Orthodontics; Edition Fourth;
Mosby 2007
• Kharbanda O.P ;Orthodontics diagnosis and
management of malocclusion and dentofacial
deformities; Edition second;2013

108. • Grabers textbook of orthodontics;4th
edition;2009
• Vibratory stimulation increases interleukin-1
beta secretion during orthodontic tooth
movement. Angle Orthod. 2016 Jan;86(1):74-80.
• Gurkeerat singh; textbook of
orthodontics;second edition;2007

109. • Effect of micro-osteoperforations on the rate of tooth
movement; ManiAlikhani; MarkosRaptis; BillieZoldan
American Journal of Orthodontics and Dentofacial
Orthopedics, Volume 145, Issue 3, March 2014, Pages
273.
• Watted N et al: Influence of drugs on orthodontic tooth
movement :Journal of Research in Medical and Dental
Science | Vol. 2 | Issue 4 | October –December 2014

110. • Moving an Ankylosed Central Incisor Using
Orthodontics,Surgery and Distraction Osteogenesis;
Angle Orthodontist, Vol 71, No 5, 2001ISAACSON,
STRAUSS, BRIDGES-POQUIS, PELUSO,
LINDAUER
• Low-level laser therapy increases interleukin-1β in
gingival crevicular fluid and enhances the rate of
orthodontic tooth movement.
Varella AM, Revankar AV, Patil AK.Am J Orthod
Dentofacial Orthop. 2018 Oct;154(4):535-544

111. • thanku