1.
THE BIOLOGY OF TOOTH MOVEMENT
BY
QIRA ZIA, M SHARIQ, TOOBA QAISAR, ANUM ZAIDI, HALIMA CHAKRANI.

2.
PRESENTATION OUTLINE
1)Introduction to orthodontic tooth movement.
2)Periodontal and bone response to normal function.
3)Theories of tooth movement.
4)Phases of tooth movement.
5)Types of orthodontic forces.
6)Types of orthodontic tooth movement.
7)Definitions.
8)Deleterious effects of orthodontic forces.
9)Methods of enhancement orthodontic tooth movement.

3.
INTRODUCTION TO ORTHODONTIC TOOTH
MOVEMENT
ORTHODONTIC TOOTH MOVEMENT:
It is a biological response to interference in the physiological equilibirium of the
dentofacial complex by an externally applied force.
STIMULUS:
Force applied to teeth for purpose of causing tooth movement.
OPTIMUM ORTHODONTIC FORCE:
1)Produces rapid tooth movement
2)minimal patient discomfort
3)The lag phase is minimum
4)No marked mobility should be seen.
5)The vitality of PDL and other structures should be maintained
6)Initiates maximum cellular response.
7)Produces frontal resorption.

4.
PERIODONTAL AND BONE RESPONSE TO
NORMAL FUNCTION
1)Normal periodontal ligament space 0.25- 0.5mm
2)Component of PDL includes .
a)PDL fibers(resists the diplacement of tooth)
b)The cellular elements( fibroblasts and osteoblasts)
C)The tissue fluids.
3)Tooth movement during mastication:
a)<1 secs = PDL fluid incompressible,alveolar bone bends,
peizoelectric signals generated.
B)1-2 secs=PDL fluid expressed,tooth moves within PDL space.
C)3-5 secs=PDL fluid sqyueezed out,tissues compressed; causes
immediate pain.
4)Active stabilization phenomenon

5.
THEORIES OF ORTHODONTIC TOOH MOVEMENT….

6.
THEORIES OF ORTHODONTIC TOOTH MOVEMENT
1)PRESSURE TENSION THEORY ( Relates tooth movement to
cellular changes produced by chemical messengers, tradionally
thought to be generated by alterations in blood flow through the
PDL
2)BIOELECTRIC/BONE BENDING THEORY ( Relates tooth
movement at least in part to changes in bone metabolism
controlled by electric signals that are produced when alveolar
bone flexes and bends

7.
PRESSURE-TENSION THEORY
BY Sandstedt 1904, Oppenheim 1911, Schwarz 1932
The pressure tension theory relates tooth movement to cellular changes
produced by chemical messengers,tradionally thought to be generated by
alterations in blood flow through PDL.
Force applied alteration in blood flow with pressure and tension in pdl
formation and release of chemical messengerscellular differentiation
Remodelling [Resorption(pressure side), Deposition(tension side)]
HISTOLOGICAL CHANGES DURING TOOTH MOVEMENT:
1)Changes following applicaton of mild force.
2)Changes following application of extreme force..

8.
PRESSURE-TENSION THEORY
BY Sandstedt 1904, Oppenheim 1911, Schwarz 1932
1)CHANGES FOLLOWING APPLICATION
OF MILD FORCE:
A)CHANGES ON PRESSURE SIDE:
1)Periodontal ligament gets
compressed to almost 1/3rd .
2)A marked increase in vascularity of
PDL due to inc in capillary blood flow. This
increase helps in mobilazation of cells such as
fibroblasts and osteoclasts.
3)Osteoclasts are bone resorbing cells that
ine up along the socket wall on pressure side,
and they start resorbing bone.
4)when the forces applied are within the
physilogical limits, the resorption in the
alveolar plate immediately adjacent to the
ligament.this kind of resorption is known as
FRONTAL RESORPTION.
B)CHANGES ON TENSION SIDE:
1)Periodontal membrane on tension side
get stretched & so distance between the
alveolar process and tooth is widened.
2)Raised vascularity as on pressure side and
causes mobilization of cells such as
fibroblasts and osteblasts. Osteoid is laid
down immediatley adjacent to lamina dura
which later on mature to woven bone.

9.
PRESSURE-TENSION THEORY
BY Sandstedt 1904, Oppenheim 1911, Schwarz 1932
2)CHANGES FOLLOWING APPLICATION OF
EXTREME FORCES:
A)CHANGES ON PRESSURE SIDE:
1)When extreme forces are applied it
results in crushing or total compression of
PDL.
2)On the pressure side root closely
approximates the lamina dura
compresssed PDL occlusion of blood
vesselsDec. nutrional supply regressive
changes(Hyalinization).
3)In this case, bone resorpton occurs in
the adjacent marrow spaces and in the
alveolar plate behind and above the
hyalinized zones. This kind of resorption is
known as UNDERMINING RESORPTION.
B)CHANGES OF TENSION SIDE:
1)On tension side, the periodontal
ligament gets over stretchedtearing of
blood vessels and ischemia.

10.
BIOELECTRIC/BONE BENDING THEORY
Relates tooth movement at least in part to changes in bone metabolism controlled by
electric signals that are produced when alveolar bone flexes and bends.
Force applied(alveolar bone bends and flexes)Electrical signals generated
change in bone metabolismtooth movement.
CHANGE IN BONE SURFACES:
1)PDL pressure side: Convex(electro positive, Osteoclastic activity).
2)PDL tension side: Concave(electro negative, Osteoblastic activity).
BIOELECTRIC RESPONSES:
1)Piezoelectric phenomenon.
2)Streaming potential.

11.
BIOELECTRIC/BONE BENDING THEORY
1)PIEZOELECTRICITY:
Piezoelectricity is the phenomenon observed in many crystalline materials in which
a deformation of crystal structure produces a flow of electric current as electrons are
displaced from one part of crystal lattice to another.
A small electric current is generated when bone is mechanically deformed. The
possible sources of the electric current are:
A)collagen.
B)Hydroxyapatite.
C)Collagen-Hydroxyapatite interface.
D)Mucopolysacchride fraction of the ground substance.
Piezoelectric signals have two unusual characterstics:
A) Quick decay rate: When a force is applied , a peizoelectric signal is produced.
This electric current quicly dies away to zero when though
force is maintained.
B)When the force is released, electron flow in opposite direction is seen.

12.
BIOELECTRIC/BONE BENDING THEORY
2)STREAMING POTENTIAL:
Ions in the fluidinteract with complex electric fieldBoth conduction and
convection currents can be detectedthe small voltages obsereved are known as
streaming potential.
Fluid flow with long decay period.

13.
CHEMICAL REGULATION OF ORTHODONTIC TOOTH
MOVEMENT….

14.
CHEMICAL REGULATION OF OTM
CHEMICAL MESSENGERS:
It is because of both mechanical and compression of tissues and changes in blood
flow can cause release of chemical messengers.
What happens after force is applied?
A)Release of First messengers.
B)Role of Mechanoreceptors.
C)Release of Second Messengers.
D)Other Messengers.

15.
Diagrammatic representation of increasing compression of blood vessels as
pressure increases in the PDL. At a certain magnitude of continuous pressure , the
blood vessels are totally occluded.

16.
SEQUENCE OF EVENTS
LIGHT FORCE:
Within seconds:
1)movement of fluids from areas of compressionareas of tension
2)development of strain in cells and extracellylar matrix
3)Intracellular ca++ , Increase CAMP, increase Phospholipase activity.
Within mintues:
1)blood flow altered and oxygen tension begins to change
2)Prostaglandins and cytokines release.
Within hours:
1)Metabolic changes occur/enzyme release.
2)After 4 hours: Inc. CAMP levels are present & cellular differentiation begins
within PDL.
Within days:
1) 2days: Activation of cells to participate in remodellingtooth movement
2) 5-7 days: Days to remove necrotic bone.

17.
SEQUENCE OF EVENTS
HEAVY FORCES:
Within Minutes:
flow of blood cut off
Within Hours:
cell death occurs in compressed areas.
Within Days:
1) 3-5 days: cell differentiation, undermining resorption.
2) 7-14 days: Undermining resorption in lamina dura adjacent to compressed
PDL  tooth movement occurs.

18.
PHASES OF TOOTH MOVEMENT…

19.
PHASES OF TOOTH MOVEMENT
Burstone categories the phases as
1)Initial Phase
2)Lag Phase
3)Post lag Phase

20.
PHASES OF TOOTH MOVEMENT
INITIAL PHASE:
1)Rapid tooth Movement is observed over a short distance
2)Represents displacement of tooth in PDL membrane space and bending of alveolar
bone
3)Both light and heavy forces displace the tooth to same extent during this phase
4)Movement is about 0.4mm to 0.9mm in a weeks time
5)Time Duration: 24 hours to 2 days

21.
PHASES OF TOOTH MOVEMENT
LAG PHASE:
1)Duration : 4 to 20 days
2)Little or no tooth movement occurs
3)This phase is characterized by formation of hyalinizied tissue in PDL which has to
be resorbed before further tooth movement can occur.
4)Duration of lag phase depends upon the amount of force use to move the tooth

22.
PHASES OF TOOTH MOVEMENT
POST LAG:
1)Tooth movement progresses rapidly as the hyalinized zone is removed and bone
undergoes resorption.
2)Also known as accelerated phase
3)During this phase osteoclasts are found all over the large surface area resulting
in direct resorption of bony surface facing the PDL
4)Duration: 40 days after initial force application

23.
TYPES OF ORTHODONTIC FORCES…

24.
TYPES OF ORTHODONTIC FORCES
There are 3 types of orthodontic forces that are delivered to the tooth by help of
appliances.
1)Continuous force
2)Interrupted force
3)Intermittent force

25.
TYPES OF ORTHODONTIC FORCES
CONTINOUS FORCE:
1)achieved via fixed appliances
2)example : braces
3)It never declines to zero
4)Alveolar bone resorbed at the pressure sites
5)Deposition of new bone at the PDL tension site.

26.
TYPES OF ORTHODONTIC FORCES
Interrupted Force :
1)Achieved via removable appliances
2)force starts heavy then decline to optimal and after that may reach zero
3)short hyalinization periods are formed
4)small compression zone is formed

27.
TYPES OF ORTHODONTIC FORCES
INTERMITTENT FORCE :
1)Achieved via extra oral appliance
2)example : Headgear
3)semi hyalinization
4)force fall to zero when the appliance is removed
5)Forces resume when the appliance is reinserted

28.
TYPES OF ORTHODONTIC TOOTH MOVEMENTS…

29.
TYPES OF ORTHODONTIC TOOTH MOVEMENTS
Orthodontic tooth movement are of various types depending on the amount of
force and the time duration the force is applied for.
There are 7 types of orthodontic tooth movements.

30.
TYPES OF ORTHODONTIC TOOTH MOVEMENTS

31.
DEFINITIONS…

32.
DEFINITIONS
FORCE:
A load applied to an object that will tend to move in a different position in
space.
MOMENT:
1)A measure of the tendency to rotate an object around some point .
2)Generated by a force acting at a distance
3)Moment =magnitude of force * distance (perpendicular distance from the center of
resistance of the body to the line of action of the force)
4)Measure in units of grams-millimeters.
CENTER OF RESISTANCE:
1)A point where the whole body weight is concentrated and is termed as center of
gravity
2)Center of resistance for tooth is at the approximate midpoint of the embedded
portion of the root

33.
DEFINITIONS
COUPLE:
1)Two equal forces acting in opposite directions.
2)Couple results in pure rotational movement about the center of resistance.
CENTER OF ROTATION :
1)The point around which the rotation actually occurs when an object is being moved
2)Center of rotation could be at the center of resistance, apical or at infinity.
3)Its position will determine the type of tooth movement.

34.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES…

35.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES
DELETERIOU
S EFFECTS
PAIN
ALLERGY
MOBILITY
GINGIVA
PULP
VITALITY
ROOT
RESORPTIO
N
WHITE SPOT
LESION
ENAMEL
TRAUMA

36.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES
PAIN:
1)On application of appropriate orthodontic forces, patient initially feels little to no
pain IMMEDIATELY.
2)Mild aching pain develops SEVERAL HOURS LATER
3)Teeth are sensitive to pressure
4)Pain usually last 2 to 4 days
5)Pain is associated with orthodontic treatment is related to the development of
ischemic areas in the PDL (which may undergo sterile necrosis)
6)Peri-apical inflammation and mild pulpitis may also be a contributing factor to pain
after orthodontic forces are applied.
7)If light forces are used, the amount of pain experienced by the patient can be
reduced by having them engage in repetitive chewing. This allows blood flow through
compressed areas.
8)ACETAMINOPHEN can be used for pain management.
9)Drugs like NSAIDs, ibuprofen and other prostaglandin inhibitors are
contraindicated.

37.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES
ALLERGIC REACTIONS:
1)Some patients develop allergic reactions to two objects; latex gloves and Nickel.
2)Nickel may be present in stainless steel wires and brackets
3)Allergic reaction manifest as erythema and swelling of oral tissue which develops
usually in a day or two
4)Titanium can be substituted against Nickel in such patients.

38.
DELETERIOUS EFFECTS OF ORTHODONTIC
FORCES
MOBILITY:
1)Mobility is observed due to effects of orthodontic forces on PDL fibers.
2)PDL space widens
3)PDL disorganize and reorganize themselves
4)Force is directly proportional to mobility.
5)Excessive forces may lead to undermining resorption

39.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES
PULP VITALITY:
1)Transient inflammatory response within the pulp may occur initially
2)This initial mild pulpitis has no long term significance
3) History of previous trauma
4) Heavy continuous forces → Undermining resorption → Blood vessels engorged
at root apex→ Loss of Pulp vitality
5)Endodontically treated teeth can be moved for orthodontic purposes
6)Calcium Hydroxide is filled in tooth with intrusive trauma until tooth movement
is completed.

40.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES
ROOT RESORPTION:
1)Cementum adjacent to hyalinized areas of the PDL undergo resorption by
cementoclasts
2)Heavy continuous orthodontic forces can lead to severe root resorption
3)Even with most careful control of orthodontic forces, it is difficult to avoid creating
some hyalinized areas
4)Excessive resorption by cementoclasts will cause dentine destruction
5) Once orthodontic forces are removed, repair occurs by the deposition of new
cementum in the area of previous destruction
6)Dentin once lost will not be replaced
7)Loss of root structure occurs primarily at root

41.
Root
Resorption
Moderate
Generalized
Severe
Generalized
Severe
Localized

42.
DELETERIOUS EFFECTS OF ORTHODONTIC FORCES
WHITE SPOT LESION:
1)Sub surface enamel porosity
2)Most common on maxillary lateral incisors during young age
3)Predisposed by poor oral hygiene
4)Can be prevented by Fluoridated water,Fluoride Toothpaste, Fluoride Varnish.

43.
DELETERIOUS EFFECTS OF ORTHODONTIC
FORCES
ENAMEL TRAUMA:
1)Enamel trauma can be caused by bracket application, bracket removal and de-
bonding
2)Applying Ceramic brackets on lower incisors can cause trauma on the maxillary
incisors.
3)Iatrogenic causes of enamel trauma include debonding.
4)To prevent de-bonding enamel trauma, debond carefully using carbon dioxide
laser or electro-thermal techniques

44.
EFFECTS ON ORTHODONTIC TOOTH MOVEMENT…

45.
EFFECTS ON ORTHODONTIC TOOTH MOVEMENT
OTM ALTERATION
PHARMACOLOGICAL
ENHANCEMENT OF
OTM
IMPEDENCE OF OTM
SURGICAL
DISTRACTION
OSTEOGENESIS
ACCELERATED
OSTEOGENESIS
ORTHODONTICS
MODIFIED
CORTICOTOMY
OTHER METHODS
VIBERATION OF
TEETH
LIGHT APPLICATION
THERAPEUTIC
ULTRASOUND

46.
PHAMACOLOGICAL: DRUGS WHICH ENHANCE OTM
1)Prostaglandins have shown to increase the rate of tooth movement.
2)However, application of prostaglandin injections in PDL is painful
3)Vitamin D administration have also proven to help in orthodontic movement

47.
PHAMACOLOGICAL: DRUGS WHICH RETARD OTM
BISPHOSPHONATES – for Osteoporosis
– Alendronate (Half life of 12 years)
PROSTAGLADIN INHIBITORS
– Indomethacin
– NSAIDs: Asprin and Ibuprofen
TETRACYCLINES
– Doxycycline
TRICYCLIC ANTIDEPRESSANTS
– Doxepine
– Imipramine
ANTIARRHYTHMIC agents
– Procaine
ANTIMALARIALS Drugs
– Quinine
– Chloroquine

48.
BISPHOSPHONATES:
1)Act as specific inhibitors of osteoclast mediated bone resorption.
2)BIONJ
3)Bisphosphonate incorporate
1. in structure of bone
2. On surface of bone
4)Estrogen analogues can be used instead

49.
SYNTHESIS OF PROSTAGLANDINS

50.
SURGICAL: DISTRACTION OSTEOGENESIS
1)Ankylosed tooth movement is only possible if the bone moves.
2)In order to attain tooth movement, a segment of the bone surrounding the
tooth is moved
3)Distraction of Alveolar Segment

51.
SURGICAL:
ACCELERATED OSTEOGENESIS ORTHODONTICS
1)Areas of decortication over facial surface of alveolar bone
2)Place bone grafting material; deminerialized freeze-dried bone
3)Demineralization-Remineralization phenomenon produces accelerated bone
remodeling that allows faster tooth movement.

52.
SURGICAL: MODIFIED CORTICOTOMY
1)Incisions are made in the interproximal gingiva, so reflecting flaps is not
necessary
2)Peizoelectric knife is used to penetrate the cortical bone
3)A tunnel towards the medullary space is thus established
4)Graft slurry is injected into the are with syringe

53.
OTHERS: VIBRATION OF TEETH:
1)Induction of Peizoelectric current
2)Frequency: 30Hz
3)20 mins per day
4)Stimulates cell differentiation and maturation

54.
OTHERS: PHOTOTHERAPY
1)Uses light with wavelength of 800 to 850 nm for 20 mins per day
2)Infuses light energy directly into bone tissue
3)97% of light energy is lost before it penetrates, thus remaining 3% is said to have
enough energy to excite intracellular enzymes and increase cellular activity
4)Also has been shown to increase blood flow.

55.
OTHERS: THERAPUETIC ULTRASOUND
1)Reduced root resorption to facilitate OTM
2)Increased blood flow in PDL would decrease the formation of hyalinized area,
thus increasing rate of bone remodeling and tooth movement

56.
THANKYOUUU
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