ortho lab - session 1 Flashcards
what is a TPA constructed in?
0.9mm HSSW
how is a TPA normally attached to FPMs?
using ortho SS bands
attach appliance using spot welding/soldering
why doesn’t a TPA touch the palate?
because the palate would grow over it
uses of a TPA
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
what is a palatal arch with a nance button constructed in?
0.9mm HSSW
construction and adjustment of a palatal arch with a nance button
constructed in a rigid fixed manner and requires minimal adjustment prior to fitting
adjustment ear loops, acrylic button
how is a palatal arch with a nance button attached to FPMs?
use ortho SS bands, attach appliance using spot welding/soldering
uses of a palatal arch with a nance button
anchorage - prevents 6s moving anteriorly
problems with a palatal arch with a nance button
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
quad helix versatility
versatile - can adapt
what is a quad helix constructed in?
0.9mm (1mm) HSSW
construction and adjustment of a quadhelix
constructed in a rigid fixed manner and requires minimal adjustment prior to fitting
how is a quad helix attached to FPMs?
using ortho SS bands, attach appliance to it using spot welding/soldering
uses of a quadhelix
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
quadhelix asymmetric expansion
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
why do CLP patients nearly always have a narrow arch?
operation - scar tissue inhibits natural expansion of arch
what needs to be placed in a visit before inserting quad helix?
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
quad helix construction
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
tack/spot welding
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
why can’t you use lead for soldering
low mp (too soft) carcinogenic
soldering flux powder
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
microtorch
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
once soldered how do you place the quad helix?
saw through teeth either side on cast to remove, smooth and trim
then cement with GIC in mouth
