ortho lab - session 1

Question 1

what is a TPA constructed in?

Answer 1

0.9mm HSSW

Question 2

how is a TPA normally attached to FPMs?

Answer 2

using ortho SS bands

attach appliance using spot welding/soldering

Question 3

why doesn’t a TPA touch the palate?

Answer 3

because the palate would grow over it

Question 4

uses of a TPA

Answer 4

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

Question 5

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

Answer 5

0.9mm HSSW

Question 6

construction and adjustment of a palatal arch with a nance button

Answer 6

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

Question 7

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

Answer 7

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

Question 8

uses of a palatal arch with a nance button

Answer 8

anchorage - prevents 6s moving anteriorly

Question 9

problems with a palatal arch with a nance button

Answer 9

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

Question 10

quad helix versatility

Answer 10

versatile - can adapt

Question 11

what is a quad helix constructed in?

Answer 11

0.9mm (1mm) HSSW

Question 12

construction and adjustment of a quadhelix

Answer 12

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

Question 13

how is a quad helix attached to FPMs?

Answer 13

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

Question 14

uses of a quadhelix

Answer 14

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

Question 15

quadhelix asymmetric expansion

Answer 15

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

Question 16

why do CLP patients nearly always have a narrow arch?

Answer 16

operation - scar tissue inhibits natural expansion of arch

Question 17

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

Answer 17

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

Question 18

quad helix construction

Answer 18

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

Question 19

tack/spot welding

Answer 19

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

Question 20

why can’t you use lead for soldering

Answer 20

low mp (too soft)
carcinogenic

Question 21

soldering flux powder

Answer 21

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

Question 22

microtorch

Answer 22

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

Question 23

once soldered how do you place the quad helix?

Answer 23

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