Biomechanics III Flashcards
What is the effect on the bone to the compressed area?
Pressure –> resorption (osteoblastic activity)
What is the effect on the bone to the stretched area?
Tension –> apposition (osteoblastic activity)
What are the resorption areas? (2)
- Frontal resorption
- undermining resorption
What occurs with frontal resorption? (2)
- LIGHT forces < capillary blood pressure
- Force doesn’t disrupt blood supply
What occurs with undermining resorption? (2)
- HEAVY forces > capillary blood pressure
- Forces block blood supply
Frontal resorption light forces: blood supply?
Reduced
Frontal resorption light forces: cells?
2
- cellular activation and differentiation
- local osteoclasts resorb bone
Frontal resorption light forces: resorption?
frontal (periodontum - bone)
Frontal resorption light forces: tooth movement?
takes place lapsed 4-6 hours
Frontal resorption light forces: tooth movement progression?
smooth
Result of continuous light forces? (4)
- osteoclasts initiate resorption of lamina dura from side of PDL
- 1st wave of osteoclasts derived from PDL itself
- 2nd wave (larger) from distance areas via blood flow
- leads to FRONTAL RESORPTION
Undermining resorption heavy forces: Blood supply
- cut off/totally occlude blood vessels
Undermining resorption heavy forces: cells?
4
- cell lysis
- sterile necrosis
- hyalinized (36 hours)
- PDL fibers and cells reorganize
Undermining resorption heavy forces: resorption? (3)
- marrow resorption (bone - periodontum)
- tunnel resorption
- osteoclasts com from far away
Undermining resorption heavy forces: necrosis?
eliminated
Undermining resorption heavy forces: tooth movement?
- begins at 7-14 days
- jump movement
What does Gianelly 50 gr do?
Doesn’t affect vessel bundle
What does Gianelly 100 gr do?
Blood supply is reduced
What does Gianelly 150 gr do?
Total block of blood supply
Undermining resorption heavy forces: PDL fibers and cells?
reorganize
Heavy forces: 3-5 seconds? (2)
◼ Minutes: Blood Flow cut off compressed PDL areas
◼ Hours: cell death in compressed area
Heavy forces: 3-5 days? (3)
◼ Cell differentiation in adjacent marrow spaces
◼ Osteoclasts get to necrotic spot: tunnel resorption
◼ Undermining resorption begins
Heavy forces: 7-14 days? (3)
◼ Resorption of all necrotic material
◼ Resorption removes lamina dura adjacent to compressed PDL
◼ Tooth movement occurs in a “jump”
What are the cellular changes that occur with forces? (4)
Loss of blood flow causes sterile necrosis of the PDL
A “Hyalinized” area devoid of cells and vasculature
develops
Osteoclasts appear within the adjacent bone marrow
spaces and begins an attack on the underside of the
bone immediately adjacent to the necrotic PDL area
An initial delay in tooth movement occurs
There a delay in tooth movement with forces because…? (2)
• stimulating cell differentiation in the marrow
• A considerable thickness of bone has to be removed
from the underside
look at slide 12
do it
Apposition area? (2)
- later than resorption: transient increase of periodontal space
- to maintain bone thickness
What does the apposition area need? (3)
- Blood supply
- Cell proliferation
- cell activation
What steps occur with apposition? (6)
- Tension caused by PDL fiber stretching
- Negative potentials
- Osteoblastic activity deriving from PDL stem cells
- Nonabsorbable osteoid tissue formation - 9 or 10 days
- Tissue calcification through salt deposit
- Reconstruction and organization of fibers
What are the effects on the pulp from force? (4)
Transient inflammatory response
- vessel trauma
- hyper sensibility or pain
- spontaneous remission
There is risk of pulp necrosis with force if…(4)
◼ Intense and continuous forces with many hyalinizations
◼ Previous trauma to the tooth
◼ Rude intrusion or extrusion movements
◼ More frequent in adults
Pulp from force: devitalized teeth? (2)
- Treatment possible
- more risk of radicular resorption
Root remodeling occurs by…? (3)
- Resorption and apposition of cementum
- Action of intense and lasting forces
- Intense load may cause kinking of the root apex
What are the two types of root resorption? (2)
- lateral
- longitudinal
What are the types of lateral root resorption?
- Surface resorption (only cementum
- Deep resorption (cementum and dentin)
What is surface root resorption? (6)
- Lateral resorption ◼ Most frequent ◼ Caused by excessive load and cementoclasts ◼ Microscopic ◼ Can be repaired if forces are removed - only cementum
What is deep resorption? (6)
- Lateral resorption
- Cementum and dentin
◼ Macroscopic crater defects
◼ Caused by uprooting (tear down)
◼ Excessive load
◼ Can’t be repaired
What happens with longitudual resprtion?
- Minimal loss can’t be observed on OPG
- Intense continuous lasting forces
Where are longitudinal resorptions more frequent? (4)
◼ Lateral upper incisor
◼ Central upper incisor
◼ Lower incisors
◼ 1st lower premolar
(all incisors and 1st lower premolar)
What are the risk factors for longitudinal resorption? (8)
◼ Intense and lasting forces ◼ Conic Sharp roots ◼ Tooth shape anomalies (dilaceration) ◼ Previous trauma ◼ Endodontic treatment ◼ Adults ◼ Tooth with previous resorption ◼ Contact of apex with cortical plate
How do we clinically manage root resorptions? (6)
Explain risk to parents
Periapical X-ray of lateral upper incisor every 6 months
◼ Periapical X-rays of all teeth
◼ Release force for 4 weeks
◼ Resorption will continue 9-10 days after force release
◼ Formation of nonabsorbable restorative cementum
What does white spot lesions and decalcification signify? (2)
- Absence of hygiene
- Gingival fluid filtration through adhesión material (bad technique)