ortho lab - session 1 Flashcards

1
Q

what is a TPA constructed in?

A

0.9mm HSSW

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2
Q

how is a TPA normally attached to FPMs?

A

using ortho SS bands

attach appliance using spot welding/soldering

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3
Q

why doesn’t a TPA touch the palate?

A

because the palate would grow over it

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4
Q

uses of a TPA

A

anchorage - fixates 6s together so they can’t move independently - significantly increases tooth area - need more force to move all of this
rotation
limited widening or contraction

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5
Q

what is a palatal arch with a nance button constructed in?

A

0.9mm HSSW

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6
Q

construction and adjustment of a palatal arch with a nance button

A

constructed in a rigid fixed manner and requires minimal adjustment prior to fitting
adjustment ear loops, acrylic button

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7
Q

how is a palatal arch with a nance button attached to FPMs?

A

use ortho SS bands, attach appliance using spot welding/soldering

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8
Q

uses of a palatal arch with a nance button

A

anchorage - prevents 6s moving anteriorly

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9
Q

problems with a palatal arch with a nance button

A

hygiene - can’t remove acrylic (plaque trap, ulcers, candida etc)
some pts unable to tolerate
not good for moving 6s distally
- open ear loops to apply distal force, but then moves band, causes tipping of tooth, roots moved mesially - not an ideal appliance to do this with

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10
Q

quad helix versatility

A

versatile - can adapt

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11
Q

what is a quad helix constructed in?

A

0.9mm (1mm) HSSW

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12
Q

construction and adjustment of a quadhelix

A

constructed in a rigid fixed manner and requires minimal adjustment prior to fitting

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13
Q

how is a quad helix attached to FPMs?

A

using ortho SS bands, attach appliance to it using spot welding/soldering

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14
Q

uses of a quadhelix

A

anchorage
bilateral expansion
asymmetrical expansion (moving both sides but to different degrees)
fan style expansion
rotation of molars
expansion in CLP
modified to procline incisors - extend wires, anterior helices
assist in habit breaking - disrupt seal between thumb and roof of mouth
unilateral contraction
on completion of tx the appliance can be made passive and recemented to use as a retainer

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15
Q

quadhelix asymmetric expansion

A

moving both sides but to different degrees
difficult to achieve because of newtons 3rd law
adjust coil so close to teeth
cut end of wire - moving less teeth with same force
by the time force gets to the other coil the force will have been dissipated by the coils a bit

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16
Q

why do CLP patients nearly always have a narrow arch?

A

operation - scar tissue inhibits natural expansion of arch

17
Q

what needs to be placed in a visit before inserting quad helix?

A
place spacers both sides of 6s
leave 1week
not bone remodelling, just pushing teeth apart - compressing teeth in PDLs
can be a bit uncomfortable for some pts
probe to remove
18
Q

quad helix construction

A

band

  • buccal aspect has attachment and hook - hook always points in distal direction
  • slot for wire to go through
  • also area of tubing which you can attach headgear to, but rarely used as v unpopular
  • band size - wire gauge. don’t want jammed onto tooth, need small gap for GIC (fixates in position and ensures seal so no cleansing issues)

place bands in pts mouth

  • take imp - ensure tray large enough
  • alginate - remove imp and bands should be securely in alginate - don’t use silicone as not much elasticity so pulls brackets off
  • lab pours cast in 100% stone

use pliers to make anterior coils first then posterior
- doesn’t touch palate

19
Q

tack/spot welding

A

copper good conductor of electricity - 2 copper electrodes
SS not good conductor - becomes heat instead as resistance - extreme heat - tape and band spot weld together
physical joint - changing molecular structure
need good connection otherwise get flashing
wrap tape around wire - secure it above and below
- cut excess tape off

20
Q

why can’t you use lead for soldering

A
low mp (too soft)
carcinogenic
21
Q

soldering flux powder

A

mostly K
add couple of drops of H2O and mix paste
use to dissolve any C as being formed - oxidation forms C when heat
solder flows into pits and fissures on SS to make good join
C would flow into pits and prevent this
place flux over and around join

22
Q

microtorch

A

flame onto joint - flux starts to bubble
add solder - a wire - flushes into joint
quench v quickly to prevent annealing (cold water)
if get annealing take SS back to soft state which prevents it applying force

23
Q

once soldered how do you place the quad helix?

A

saw through teeth either side on cast to remove, smooth and trim
then cement with GIC in mouth