Tooth movement Histology Flashcards
Two main types of tooth movement
Physiological and orthodontically
Physiological tooth movement (includes 3 things)
- Tooth eruption
- Migration or drifting movements of teeth
- Tooth movement during Mastication
Two reasons for migration/drifting of teeth physiological
- Due to Missing teeth or Space loss
* Due to Facial Growth
Define tooth eruption
Vertical or axial movement of the tooth from its developmental position with in the jaw to its functional position in the occlusal plane.
Stages of eruption (list them)
pre-eruptive
eruptive
post-eruptive
Bone and tooth eruption involve what two things
• Involve bone remodeling and soft tissue removal
Define/explain migration or drifting of teeth
The ability of teeth to drift through the alveolar bone
Migration post eruption, significant? Direction
Minor changes
Mesial occlusal
(maintain proximal contacts)
Migration post eruption favors which direction
medial-occlusal post eruptive movement for maintaining inter proximal and occlusal contacts
Migration due to facial growth happens in which direction and why
ant and laterally due to an increase in the arch size
The arch does what as permanent molars develop and erupt
Arch increases posteriorly as molars develop
Alveolar bone growth with facial growth
direction?
In relation to what
The HEIGHT of the alveolus bone increases in relation to root growth as part of the facial growth.
Transverse movement stops when
Stops at age 7
Primary incisors smaller than permanent, how do we get space for the new bigger teeth? (2)
Accommodation for the increased dimension of the permanent teeth is made by Lee way space and incisors
liability
Leeway space
Define?
What is it important for?
A leeway space is created in the arches by the replacement of larger primary molars for smaller permanent premolars.
This is important and compensate for the incisor liability factor.
leeway space gained per quadrant in maxilla and mandible
- 5mm in max
2. 5mm in mand
INCISOR LIABILITY
define
The difference in space between the permanent incisors and the primary which is required for proper alignment of the permanent incisors is called incisors liability.
Normal forces of mastication can range between
(1-50kg)
Tooth movement during mastication occurs in cycles of what duration
What if mastication goes beyond this?
1 second duration- will feel pain if this goes longer than 1-2s
When we chew, how do teeth move
Teeth exhibit slight movement in the socket and return to their original position on withdrawal of the force.
What happens when chewing force is sustained for more than 1 second?
Explain
Periodontal fluid is squeezed out and pain is felt as tooth is
displaced with in the periodontal space
Width of PDL around the root
0.5mm
PDL is made of (2)
collagen fibers and tissue fluids
PDL function **
What helps maintain movement of tooth?
Resists displacement of the teeth during normal function
Tissue fluid=movement
Cellular elements of PDL (3)
Cellular elements mesenchymal cells
neural
vascular
Stem cell of fibroblast and osteoclast
Mesenchymal cells
Stem cells of osteoclast and cementoclasts
Hematopoitec
Structures involved in the biology of orthodontic tooth movement
(5)
- External orthodontic Forces
- Tooth
- Periodontal ligament
- Alveolar Bone
- Extracellular fluid
WHAT HAPPENS DURING ORTHODONTIC TREATMENT?
What causes tooth movement?
What happens to the bone?
Prolonged forces on a tooth will result in tooth movement
The bone surrounding the tooth remodels
Remodeling = bone is removed (resorption) in some areas and added
(apposition) in other areas
With bone remodeling what happens (think how and with what the tooth moves)
The tooth moves in the bone carrying its attachment apparatus with it (PDL), as
the socket of the tooth migrates.
Response to orthodontic force is mediated by what
PDL
The _______ is constantly being remodeled and
renewed during normal physiological function.
collagen of the ligament
Remodeling of collagen in the PDL during normal function is caused by what
This is preformed by the fibroBLASTS producing new collagenous matrix
materials, and fibroCLASTS removing it.
Bone changes physiological vs orthodontic
Bone, which is more intense? why?
The alveolar bone and cementum is constantly being remodeled, though
on a smaller scale, as a response to normal function.
However, during the orthodontic treatment the remodeling process is
more intense, due to the prolonged period of force applied to the teeth.
The PDL resists forces of _____ from chewing.
short duration (1-5seconds)
The ____ has the potential to “generate forces” which promote tooth movement in the case of eruption of teeth; and to counter
unbalanced forces under normal conditions (stabilization).
PDL
What absorbs force while we chew
Be specific
The periodontal ligament space filled with tissue fluids and the supporting
alveolar bone are designed to absorb the forces of normal function e.g. Chewing.
When a tooth is subjected to heavy loads of (Chewing forces of less than _____ displacement of the tooth within the PDL space is prevented by
the incompressible tissue fluid.
1 second
The force beyond 1s is absorbed by what?
How does this structure respond?
What does this create?
absorbed by alveolar bone which bends back and produces piezoelectirc currents within the bone
Response of bone bending under force causes
piezoelectirc currents
Physiological response to heavy force of <1 second
3
- PDL fluid compressed
- Alveolar bone bends
- Piezoelectric signal generated
Physiological response to heavy force of (1-2 seconds)
2 things
PDL Fluid expressed
Tooth moves within the PDL space
Physiological response to heavy force of 3-5s
3 things
PDL fluid squeezed out
Tissue compressed
Immediate pain if pressure is heavy
WHAT HAPPENS IN THE CASE OF ORTHODONTIC TOOTH MOVEMENT?
Think F and response
• Prolonged forces generated by the orthodontic appliance
produces a different response in the PDL
• Remodeling of adjacent bone results in tooth movement
A force on a tooth will create 2 opposite sides; what are they called? Describe
one is called
Pressure/or compression) side, the other is called (Tension
Cellular response on the pressure or compression side
Osteoclasts will resorb the
bone of the socket wall (resorption) so the tooth can move
**KNOW THIS
On the tension side what is the cellular
Osteoblasts will deposit or add bone on the
opposite side of the socket (apposition).
**KNOW THIS
Blood flow as teeth move
it is altered/cut off –> change in chemical environment –> cell differentiation and activity
that is about all for now
LIGHT FORCES VERSUS HEAVY FORCES IN ORTHODONTIC TOOTH MOVEMENT
Consider
blood flow
cell response and timing
tooth moving
method of tooth movement
For light Forces.. • Blood flow is compressed but not cut off totally, with survival of PDL cells. • Osteoclasts recruitment in 2 days. • Tooth movement is faster. • Tooth movement by frontal resorption
For Heavy Forces
• Blood flow cut off for days
• Osteoclast recruitment from PDL space not possible immediately, delayed 7-14 days.
• Tooth movement is slower.
• Tooth movement is by underside resorption of
lamina dura = undermining resorption
apply more forces, will teeth move faster? Explain
NO! With optimal force osteoclast are recruited quicker. With heavy forces blood supply is cut off and osteoclast will not come as fast
Movement of heavy forces is where? What is this called
Under the lamina dura, called undermining resorption-INDIRECT
During light force, Tooth movement happens by _____
Frontal resorption-DIRECT
Pain with light or heavy forces?
More with heavy, also maybe necrosis
Optimal force must be high enough to do what and low enough to do what
- High enough to stimulate cellular activity.
- Low enough so blood vessels in PDL not occluded
• Biologic effect of tooth movement is determined by force level and area of
PDL that force is distributed (force per unit area)
• Light Force – stimulates cellular activity, remodeling by _____
direct (frontal)
resorption
• Heavy Force – creates areas of hyalinization, pain, remodeling by ______
indirect
(undermining) resorption
As force is added, vessels do what
No force=normal
Light = vessels in PDL area constricted/compressed
Heavy=blood flow to PDL cut off
Blood vessels on tension side
=Tension side, (apposition by osteoblasts), stretched blood vessels in PDL.
Compression side vessels
Compression side, (resorption by
osteoclasts), compressed blood
vessels in PDL.
Areas of beginning of the root resorption that will be repaired by what
later deposition of cementum
Orthodontic tooth movement requires a well-coupled combination of ____ and ______
as the tooth socket remodels in response to the force systems established
through the orthodontic appliance
resorption and
apposition
Orthodontic tooth movement is mediated by the PDL through localized changes
induced by areas of _____ and _____within the PDL
compression and tension
Excessive force for a long duration is destructive to the
3
bone, teeth, and pulpal tissue
Forces need to be controlled in terms of 3 things in order to effectively move teeth orthodontically.
direction, duration, and magnitude
NEGATIVE EFFECTS OF ORTHODONTIC FORCE
4
• Tooth Mobility – remodeling of adjacent bone and the fibers of PDL results in
widened PDL space during treatment. Teeth become more mobile.
• Pain – heavy pressures create immediate pain, the pressures used in routine
treatment do not produce immediate pain, pain or discomfort occurs 2-4 days
following the adjustment
• Pulp – orthodontic forces create a transient inflammatory response within the
pulp, orthodontic tooth movement will not devitalize teeth and non vital teeth
can be moved.
• Root Resorption – the cementum is affected by the resorptive process at the
same time as the osseous tissue is. The root undergoes remodeling and is
generally restored when orthodontic forces on the root cease.
Pain – heavy pressures create immediate pain, the pressures used in routine treatment do not produce immediate pain, pain or discomfort occurs____ days
following the adjustment
2-4
Tipping of the crown to the left, causes the root to ______ the PDL on the upper and lower left.
______ on the upper right and lower left.
compress
tension
Bodily movement of the crown and the root to the left causes _____ to the left on the PDL. ___ on the right side.
compression
tension
Blood vessels at tension side in PDL
Stretched
WHY RETENTION IS NEEDED AFTER TOOTH MOVEMENT IS COMPLETED?
3
- Gingival fibers and PDL fibers take long time to reorganize after treatment is completed
- Gingival fibers rearrangement take longer time (at least one year) compared to the PDL (few months)
• It is very important to place a retainer to stabilize tooth movement after the
completed.
to the PDL fibers that take (few months).
completion of the orthodontic treatment.
function of gingival ligaments and PDL
they vary-just know that
Compare the timing of rearrangement of gingival fibers and PDL
Gingival fibers rearrangement take longer time (at least one year) compared
to the PDL fibers that take (few months).
Why is it important to
place a retainer to stabilize tooth movement post treatment
because the ligaments take a while to stabalize
Orthodontic tooth movement requires what (2)
**KNOW THIS
Orthodontic tooth movement requires a well-coupled combination of
resorption and apposition as the tooth socket remodels in response to the
force systems established through the orthodontic appliance.
Ortho tooth movement is mediated by what
**KNOW THIS
Orthodontic tooth movement is mediated by the PDL through localized changes induced by areas of compression and tension within the PDL.
bone resorption and formation is regulated by what (2)
Bone resorption and formation is regulated by the dental
follicle and enamel organ.
As a tooth migrates, what happens to its PDL
The tooth moves in the bone carrying its attachment apparatus with it, as
the socket of the tooth migrates.
Force and tooth movement to the left will cause what two things
Pressure/compression on the left with osteoclast and tension on both roots with osteoblast on the right side of both roots
