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Ortho

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lunalovegood's version from 2016-10-17 19:30

Section

#1
Question Answer
0.15 - 0.38mm widePDL
70-150 lbs per [] inbite force
Compression -->resorption (decrease blood flow - osteoclasts)
Tension -->formation (increase blood flow - osteoblasts)
Tongue pressure opposedlip pressure
Post-eruptive tooth movementsremodeling of PDL collagen
Most common PDL cellfibroblasts
PDL collagens1, 3, 12 (one, six, twel - P.D.L. - but those are just minor components - #3 - is the key -)
Unmyelinated fiberspain
Large nerve fibersproprioception
Small myelinated fibersautonomic
PDL blood supplySuperior & Inferior Alveolar Arteries --> Interalveolar Arteries
Major factor in relapse after orthotranseptal fibers
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#2
Question Answer
7-10 grams per [] cmorthodontic force
Least forceintrusion (10-20g)
Moderate forceextrusion, tipping, rotation (35-60g)
Most forceroot uprighting (50-100g) and body movement (70-120g)
Sterile necrosishyalinization (heavy forces)
Only tensionextrusion
6 hoursminimum time for force to see movement
Endo treated teeth...are susceptible to root resorption w/ ortho
Force magnitude & duration, tx duration, apical root displacement, proximity to cortical bone, hx of root resorption, previous trauma, tooth root morphology, geneticsinfluence root resorption
OIIRRortho induced inflamm root resorp (max incisors > mand incisors > 1st molars) (x-rays 6months to 1 year after start)
ARRapical root resorption
EARRexternal apical root resorption
Replacement resorptionankylosis
ICRRinvasive cervical root resorption
Root is 10% ankylosednormal sound, normal mobility
Root is 20% ankylosedhigh pitch, less mobile
PAOO4 months faster
Alveocentesisclaims 50% reduction in tx time
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#3
Question Answer
Initial tx phasealign teeth (B-L, M-D, vertical, rotation, curve of Spee) (light continuous force)
Intermediate tx phasecontinue arch lvling & molar corrections, position roots, space closure (high short distance force)
Finishing tx phasesettling the dentition (flexible wire)
Internal force resisting external forcestress
Molecular movement from internal forcestrain
Stress Strain graphelastic modulus
Stiffness in TENSIONmaterial's shape does not affect & divided by cross-sectional area
Stiffness in BENDINGmaterial's shape DOES affect & NOT divided by cross-sectional area
Stiffness X RangeStrength
Wrought strengthincreased
Wrought rangeincreased
Wrought elongation/ductilitydecreased (brittle)
Wrought hardnessincreased
Stainless steel (iron + carbon) is 18% ___ and 8% ___.Chromium, Nickel
Stainless steel force deliveryhigh
Stainless steel elastic range (springback)low
NiTi force deliverylow
NiTi elastic range (springback)high
TMA force deliveryintermediate
TMA elastic range (springback)intermediate
Twice as stiff as NiTi ---- Half as stiff as SSTMA
T/F - Stainless steel is easily bent into different shapes, loops, helices, springs.True (lies! my hands still hurt!)
To release stress from bending...apply heat (Thermacare!)
Why is overheating bad?lose properties --> back to cast state --> irreversible
Soldering - aggressive flux to remove ...chromium oxide
Multi-stranded wire ___ stiffness and ___ range.decreases, increases
2 unique properties of NiTi1. Load/deflection curve 2. Shape memory (heat back to pre-determined shape)
NiTi - Heat --> ______ --> cool --> _______ ---> deform --> _____Austenite, Martensite, Deformed Martensite
2 NiTi disadvantages1. Cannot be bent chairside easily into loops or sharp bends 2. Cannot be soldered
79% Titanium + 11% Molybdenum + 10% Zirconium & TinTMA
Retains Beta crystalline form of Titanium at room temp that normally only exists at elevated temperaturesTMA
State Beam TheoryWire Deflection = Applied force X Wire length^3 / type wire support X elastic modulus X moment of inertia
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#4
Question Answer
Rectangular slot - holds either rectangular or round wireedgewise
Depth of slot greater than heightedgewise
Edge or non-edgewise more popular?edgewise
Offers 3 dimensional control of tooth movementedgewise
Aka 022 Slot applianceedgewise (0.022 x 0.028 wire size)
Vertical slot - only holds round wirenon-edgewise
Aka Begg appliancenon-edgewise
1st order bendin and out bend (B-L tooth thickness)
2nd order bendangulation bend (M-D angulation)
3rd order bendtorque bend (B-L root)
T/F - SWA eliminates need to wire bending.FALSE (just reduces needed wire bending)
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