Material Flashcards
Archwires
- Stainless steel
- Cobalt chromium
- Nickel titanium (Niti)
- TMA - Titanium Molybdenum Alloy (beta titanium)
- Aesthetic
Nickel titanium (Types of Niti)
- Classic
- Superelastic
- Heat activated
Initial Aligning wires properties?
- Low stiffness
- Low friction
- large Range
- light continuous force
- Non toxic
- low cost
Initial alignment wire options?
- 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
Nickel Titanium 3 choices
- Martensitic stable - Classic e.g. Nitinol
- Austenitic active - Superelastic or pseudo elastic.
- Martensitic active - Heat or thermally activated.
Properties of Niti ?
- Good range
- No elasticity
- high friction
- low stifness
- poor bio host
- bio compatible
Properties of Stainless steel?
- large elasticity
- high stifness
- corrosion resistance
- low friction
- good for space closure because of Low friction
- bio host
Properties of TMA? Or beta- titanium ?
- Elasticity less than SS but twice that of nitinol
- Higher firction than ss
- high cost
- formability good
Aesthetic wires
- Coated wires - White epoxy resin e.g Teflon
What wire sequence should we use?
- Initial alignment - Light and limited
- Levelling - heavier and limited
- Space closure - Stiff & low friction
- Finishing - Formable
Define friction
- A force resist relative motion of two objects in contact.
Law of friction
Friction = Force x coefficient of friction
Types of friction
- 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.
Bracket material - Friction
- Ceramic > friction than metal
- Narrow bracket > friction than wider bracket (due to critical angle)
Wire material - Friction
- Beta- titanium > friction than Niti > friction than SS.
Ligation material - Friction
- Elastomeric ligature > friction than SS ligature
- 60%- 70% more
Which moment effect by friction ?
- Tipping and bodily moment
Bracket material types?
- Metal
- Ceramic
- Polycarbonate
-Polyurethane
Morphology of brackets?
- Siamese
- Mini twin
-Single twin - Self ligating
- Tip-edge
Slot size
- 0.018X 0.028
- 22x28 common uk
- 22x30 eases tying auxiliary/piggybacks
Bracket - Metal
- Austentistic stainless steel
- If NiTi allergy can consider : Titanium , Cobalt chromium
Bracket - Bases
- Mesh commonly used fine or coarse, single 2 and 3 ply available
- Spherical photo etched undercut
- Undercut channels
- Polymer coated
Bracket - Configuration
- Straightwire or Pre adjusted edgewise system
- Commonly used we
Bracket - Siamese
- Four tie wings for better rotational control
Bracket - Self ligation
- Speed
- In - Ovation
- smart clip
- Damon
Bracket - 22x28
- most common in UK 0.022 height
- 0.028 width
- Some brackets are deeper
Andrews prescription
- This is from originator of pre adjusted edgewise appliance system
MBT prescription
- More lingual crown torque lower LBS
- less crown torque lower second molar.
- More labial torque upper incisors
- reduced tip
Self ligating brackets - Advantages
- Full archwire engagement
- Less Charside assistance required
- Less chair side time required
- less number of appointments
- Improved infection control
Self ligating - Disadvantage
- Takes practice
- Clip fracture / open b/w appointment
-No partial ligation - wire sliding round
- Cost
- no evidence of faster alingment
Why static friction?
- Teeth do not slide but walk with along archwire with small tipping and uprighting movements
Begg appliance
- Light wire appliance
What’s range
- Distance wire behaves elastically before deform
Define strength
- Stifness x strain
Formablity
- amount of permanent deformation without fracture
SS wire composition
- 71 % Fe
- 18% Cr
- 8 Ni
Niti composition
-52% Ni
- 43%
-3%
Cobalt chromium
- 40% Co
- 20 % Cr
- 15% Ni
- ## 15 % Fe
GIC made of?
- Glass poly alkenoate cement
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
Composite
- Resin BisGMA. Coupling agent
- Usually filled diacrylics
Unfilled resin primer - Bond
- Methyl methacrylate monomer
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
