Material Flashcards
1
Q
Archwires
A
- Stainless steel
- Cobalt chromium
- Nickel titanium (Niti)
- TMA - Titanium Molybdenum Alloy (beta titanium)
- Aesthetic
2
Q
Nickel titanium (Types of Niti)
A
- Classic
- Superelastic
- Heat activated
3
Q
Initial Aligning wires properties?
A
- Low stiffness
- Low friction
- large Range
- light continuous force
- Non toxic
- low cost
4
Q
Initial alignment wire options?
A
- Superelastic Niti - 0.012” to 0.014”
- Heat activated Niti - 0.016” to 0.020 “
- 0.010” single strand SS
- 0.015” - 0.018” Multi strand SS
5
Q
Nickel Titanium 3 choices
A
- Martensitic stable - Classic e.g. Nitinol
- Austenitic active - Superelastic or pseudo elastic.
- Martensitic active - Heat or thermally activated.
6
Q
Properties of Niti ?
A
- Good range
- No elasticity
- high friction
- low stifness
- poor bio host
- bio compatible
7
Q
Properties of Stainless steel?
A
- large elasticity
- high stifness
- corrosion resistance
- low friction
- good for space closure because of Low friction
- bio host
8
Q
Properties of TMA? Or beta- titanium ?
A
- Elasticity less than SS but twice that of nitinol
- Higher firction than ss
- high cost
- formability good
9
Q
Aesthetic wires
A
- Coated wires - White epoxy resin e.g Teflon
10
Q
What wire sequence should we use?
A
- Initial alignment - Light and limited
- Levelling - heavier and limited
- Space closure - Stiff & low friction
- Finishing - Formable
11
Q
Define friction
A
- A force resist relative motion of two objects in contact.
12
Q
Law of friction
A
Friction = Force x coefficient of friction
13
Q
Types of friction
A
- Static friction - Small amount of force required to initiate sliding between objects
- Kinetic friction - Amount of force resisting sliding once moving.
Important : Static friction more important as teeth do not slide but Walk along arch wire with small tippping and uprighting movements.
14
Q
Bracket material - Friction
A
- Ceramic > friction than metal
- Narrow bracket > friction than wider bracket (due to critical angle)
15
Q
Wire material - Friction
A
- Beta- titanium > friction than Niti > friction than SS.
16
Q
Ligation material - Friction
A
- Elastomeric ligature > friction than SS ligature
- 60%- 70% more
17
Q
Which moment effect by friction ?
A
- Tipping and bodily moment
18
Q
Bracket material types?
A
- Metal
- Ceramic
- Polycarbonate
-Polyurethane
19
Q
Morphology of brackets?
A
- Siamese
- Mini twin
-Single twin - Self ligating
- Tip-edge
20
Q
Slot size
A
- 0.018X 0.028
- 22x28 common uk
- 22x30 eases tying auxiliary/piggybacks
21
Q
Bracket - Metal
A
- Austentistic stainless steel
- If NiTi allergy can consider : Titanium , Cobalt chromium
22
Q
Bracket - Bases
A
- Mesh commonly used fine or coarse, single 2 and 3 ply available
- Spherical photo etched undercut
- Undercut channels
- Polymer coated
23
Q
Bracket - Configuration
A
- Straightwire or Pre adjusted edgewise system
- Commonly used we
24
Q
Bracket - Siamese
A
- Four tie wings for better rotational control
25
Bracket - Self ligation
- Speed
- In - Ovation
- smart clip
- Damon
26
Bracket - 22x28
- most common in UK 0.022 height
- 0.028 width
- Some brackets are deeper
27
Andrews prescription
- This is from originator of pre adjusted edgewise appliance system
28
MBT prescription
- More lingual crown torque lower LBS
- less crown torque lower second molar.
- More labial torque upper incisors
- reduced tip
29
Self ligating brackets - Advantages
- Full archwire engagement
- Less Charside assistance required
- Less chair side time required
- less number of appointments
- Improved infection control
30
Self ligating - Disadvantage
- Takes practice
- Clip fracture / open b/w appointment
-No partial ligation
- wire sliding round
- Cost
- no evidence of faster alingment
31
Why static friction?
- Teeth do not slide but walk with along archwire with small tipping and uprighting movements
32
Begg appliance
- Light wire appliance
33
What's range
- Distance wire behaves elastically before deform
34
Define strength
- Stifness x strain
35
Formablity
- amount of permanent deformation without fracture
36
SS wire composition
- 71 % Fe
- 18% Cr
- 8 Ni
37
Niti composition
-52% Ni
- 43%
-3%
38
Cobalt chromium
- 40% Co
- 20 % Cr
- 15% Ni
- 15 % Fe
-
39
GIC made of?
- Glass poly alkenoate cement
40
GIC - Band cement types
- Conventional glass ionomer - acid / base cement reaction
- Resin modified GIC- dual cure -acid base light cure
- Resin modified GIC - tri cure - Acid base / light cure/ chemical
- Compomer - Acid base reaction / chemical or light
41
Composite
- Resin BisGMA. Coupling agent
- Usually filled diacrylics
42
Unfilled resin primer - Bond
- Methyl methacrylate monomer
43
Self etch
- decreased no of steps in bond up
- Decreased enamel loss during etch
- Do not require rinsing , pt comfort
- Clinical performance as good as conventional
